| Message ID | 20190624055253.31183-12-hch@lst.de (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [01/12] list.h: add a list_pop helper | expand |
On Mon, Jun 24, 2019 at 07:52:52AM +0200, Christoph Hellwig wrote: > Takes the xfs writeback code and move it to iomap.c. A new structure > with three methods is added as the abstraction from the generic > writeback code to the file system. These methods are used to map > blocks, submit an ioend, and cancel a page that encountered an error > before it was added to an ioend. > > Note that we temporarily lose the writepage tracing, but that will > be added back soon. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/iomap.c | 521 ++++++++++++++++++++++++++++++++++++- > fs/xfs/xfs_aops.c | 584 ++++-------------------------------------- > fs/xfs/xfs_aops.h | 16 -- > fs/xfs/xfs_super.c | 11 +- > include/linux/iomap.h | 41 +++ > 5 files changed, 605 insertions(+), 568 deletions(-) > > diff --git a/fs/iomap.c b/fs/iomap.c > index 23ef63fd1669..72a1b622e634 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c > @@ -1,7 +1,7 @@ > // SPDX-License-Identifier: GPL-2.0 > /* > * Copyright (C) 2010 Red Hat, Inc. > - * Copyright (c) 2016-2018 Christoph Hellwig. > + * Copyright (c) 2016-2019 Christoph Hellwig. > */ > #include <linux/module.h> > #include <linux/compiler.h> > @@ -12,6 +12,7 @@ > #include <linux/migrate.h> > #include <linux/mm.h> > #include <linux/mm_inline.h> > +#include <linux/list_sort.h> > #include <linux/swap.h> > #include <linux/pagemap.h> > #include <linux/pagevec.h> > @@ -25,6 +26,8 @@ > > #include "internal.h" > > +static struct bio_set iomap_ioend_bioset; > + > /* > * Execute a iomap write on a segment of the mapping that spans a > * contiguous range of pages that have identical block mapping state. > @@ -2192,3 +2195,519 @@ iomap_bmap(struct address_space *mapping, sector_t bno, This looks like a straight code copy from fs/xfs/ into fs/iomap.c. That's fine with me, but seeing as this file is now ~2700 lines long, perhaps we should break this up among major functional lines? Looking at fs/iomap.c, I see... * Basic iomap iterator functions (~40 lines) * Page cache management (readpage*, write, mkwrite) (~860 lines) * Zeroing (~80 lines) * FIEMAP and seek hole / seek data (~300 lines) * directio (~500 lines) * swapfiles (~170 lines) * and now, page cache writeback (~520 lines) If I have spare time this week (ha ha) I'll see if I can break all this up (as a separate patch series), so for this: Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > return bno; > } > EXPORT_SYMBOL_GPL(iomap_bmap); > + > +static void > +iomap_finish_page_writeback(struct inode *inode, struct bio_vec *bvec, > + int error) > +{ > + struct iomap_page *iop = to_iomap_page(bvec->bv_page); > + > + if (error) { > + SetPageError(bvec->bv_page); > + mapping_set_error(inode->i_mapping, -EIO); > + } > + > + WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE && !iop); > + WARN_ON_ONCE(iop && atomic_read(&iop->write_count) <= 0); > + > + if (!iop || atomic_dec_and_test(&iop->write_count)) > + end_page_writeback(bvec->bv_page); > +} > + > +/* > + * We're now finished for good with this ioend structure. Update the page > + * state, release holds on bios, and finally free up memory. Do not use the > + * ioend after this. > + */ > +void > +iomap_finish_ioend(struct iomap_ioend *ioend, int error) > +{ > + struct inode *inode = ioend->io_inode; > + struct bio *bio = &ioend->io_inline_bio; > + struct bio *last = ioend->io_bio, *next; > + u64 start = bio->bi_iter.bi_sector; > + bool quiet = bio_flagged(bio, BIO_QUIET); > + > + for (bio = &ioend->io_inline_bio; bio; bio = next) { > + struct bio_vec *bvec; > + struct bvec_iter_all iter_all; > + > + /* > + * For the last bio, bi_private points to the ioend, so we > + * need to explicitly end the iteration here. > + */ > + if (bio == last) > + next = NULL; > + else > + next = bio->bi_private; > + > + /* walk each page on bio, ending page IO on them */ > + bio_for_each_segment_all(bvec, bio, iter_all) > + iomap_finish_page_writeback(inode, bvec, error); > + bio_put(bio); > + } > + > + if (unlikely(error && !quiet)) { > + printk_ratelimited(KERN_ERR > + "%s: writeback error on sector %llu", > + inode->i_sb->s_id, start); > + } > +} > +EXPORT_SYMBOL_GPL(iomap_finish_ioend); > + > +void > +iomap_finish_ioends(struct iomap_ioend *ioend, int error) > +{ > + struct list_head tmp; > + > + list_replace_init(&ioend->io_list, &tmp); > + iomap_finish_ioend(ioend, error); > + while ((ioend = list_pop(&tmp, struct iomap_ioend, io_list))) > + iomap_finish_ioend(ioend, error); > +} > +EXPORT_SYMBOL_GPL(iomap_finish_ioends); > + > +/* > + * We can merge two adjacent ioends if they have the same set of work to do. > + */ > +static bool > +iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next) > +{ > + if (ioend->io_bio->bi_status != next->io_bio->bi_status) > + return false; > + if ((ioend->io_flags & IOMAP_F_SHARED) ^ > + (next->io_flags & IOMAP_F_SHARED)) > + return false; > + if ((ioend->io_type == IOMAP_UNWRITTEN) ^ > + (next->io_type == IOMAP_UNWRITTEN)) > + return false; > + if (ioend->io_offset + ioend->io_size != next->io_offset) > + return false; > + return true; > +} > + > +void > +iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends) > +{ > + struct iomap_ioend *next; > + > + INIT_LIST_HEAD(&ioend->io_list); > + > + while ((next = list_first_entry_or_null(more_ioends, struct iomap_ioend, > + io_list))) { > + if (!iomap_ioend_can_merge(ioend, next)) > + break; > + list_move_tail(&next->io_list, &ioend->io_list); > + ioend->io_size += next->io_size; > + } > +} > +EXPORT_SYMBOL_GPL(iomap_ioend_try_merge); > + > +static int > +iomap_ioend_compare(void *priv, struct list_head *a, struct list_head *b) > +{ > + struct iomap_ioend *ia, *ib; > + > + ia = container_of(a, struct iomap_ioend, io_list); > + ib = container_of(b, struct iomap_ioend, io_list); > + if (ia->io_offset < ib->io_offset) > + return -1; > + else if (ia->io_offset > ib->io_offset) > + return 1; > + return 0; > +} > + > +void > +iomap_sort_ioends(struct list_head *ioend_list) > +{ > + list_sort(NULL, ioend_list, iomap_ioend_compare); > +} > +EXPORT_SYMBOL_GPL(iomap_sort_ioends); > + > +/* > + * Submit the bio for an ioend. We are passed an ioend with a bio attached to > + * it, and we submit that bio. The ioend may be used for multiple bio > + * submissions, so we only want to allocate an append transaction for the ioend > + * once. In the case of multiple bio submission, each bio will take an IO > + * reference to the ioend to ensure that the ioend completion is only done once > + * all bios have been submitted and the ioend is really done. > + * > + * If @error is non-zero, it means that we have a situation where some part of > + * the submission process has failed after we have marked paged for writeback > + * and unlocked them. In this situation, we need to fail the bio and ioend > + * rather than submit it to IO. This typically only happens on a filesystem > + * shutdown. > + */ > +static int > +iomap_submit_ioend(struct iomap_writepage_ctx *wpc, struct iomap_ioend *ioend, > + int error) > +{ > + /* > + * If we are failing the IO now, just mark the ioend with an error and > + * finish it. This will run IO completion immediately as there is only > + * one reference to the ioend at this point in time. > + */ > + ioend->io_bio->bi_private = ioend; > + error = wpc->ops->submit_ioend(ioend, error); > + if (error) { > + ioend->io_bio->bi_status = errno_to_blk_status(error); > + bio_endio(ioend->io_bio); > + return error; > + } > + > + submit_bio(ioend->io_bio); > + return 0; > +} > + > +static struct iomap_ioend * > +iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc, > + loff_t offset, sector_t sector, struct writeback_control *wbc) > +{ > + struct iomap_ioend *ioend; > + struct bio *bio; > + > + bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &iomap_ioend_bioset); > + bio_set_dev(bio, wpc->iomap.bdev); > + bio->bi_iter.bi_sector = sector; > + bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); > + bio->bi_write_hint = inode->i_write_hint; > + > + ioend = container_of(bio, struct iomap_ioend, io_inline_bio); > + INIT_LIST_HEAD(&ioend->io_list); > + ioend->io_type = wpc->iomap.type; > + ioend->io_flags = wpc->iomap.flags; > + ioend->io_inode = inode; > + ioend->io_size = 0; > + ioend->io_offset = offset; > + ioend->io_bio = bio; > + return ioend; > +} > + > +/* > + * Allocate a new bio, and chain the old bio to the new one. > + * > + * Note that we have to do perform the chaining in this unintuitive order > + * so that the bi_private linkage is set up in the right direction for the > + * traversal in iomap_finish_ioend(). > + */ > +static struct bio * > +iomap_chain_bio(struct bio *prev) > +{ > + struct bio *new; > + > + new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES); > + bio_copy_dev(new, prev); > + new->bi_iter.bi_sector = bio_end_sector(prev); > + new->bi_opf = prev->bi_opf; > + new->bi_write_hint = prev->bi_write_hint; > + > + bio_chain(prev, new); > + bio_get(prev); /* for iomap_finish_ioend */ > + submit_bio(prev); > + return new; > +} > + > +/* > + * Test to see if we have an existing ioend structure that we could append to > + * first, otherwise finish off the current ioend and start another. > + */ > +static void > +iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page, > + struct iomap_page *iop, struct iomap_writepage_ctx *wpc, > + struct writeback_control *wbc, struct list_head *iolist) > +{ > + unsigned len = i_blocksize(inode); > + unsigned poff = offset & (PAGE_SIZE - 1); > + sector_t sector = iomap_sector(&wpc->iomap, offset); > + > + if (!wpc->ioend || > + (wpc->iomap.flags & IOMAP_F_SHARED) != > + (wpc->ioend->io_flags & IOMAP_F_SHARED) || > + wpc->iomap.type != wpc->ioend->io_type || > + sector != bio_end_sector(wpc->ioend->io_bio) || > + offset != wpc->ioend->io_offset + wpc->ioend->io_size) { > + if (wpc->ioend) > + list_add(&wpc->ioend->io_list, iolist); > + wpc->ioend = iomap_alloc_ioend(inode, wpc, offset, sector, wbc); > + } > + > + if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) { > + if (iop) > + atomic_inc(&iop->write_count); > + if (bio_full(wpc->ioend->io_bio)) { > + wpc->ioend->io_bio = > + iomap_chain_bio(wpc->ioend->io_bio); > + } > + bio_add_page(wpc->ioend->io_bio, page, len, poff); > + } > + > + wpc->ioend->io_size += len; > +} > + > +/* > + * We implement an immediate ioend submission policy here to avoid needing to > + * chain multiple ioends and hence nest mempool allocations which can violate > + * forward progress guarantees we need to provide. The current ioend we are > + * adding blocks to is cached on the writepage context, and if the new block > + * does not append to the cached ioend it will create a new ioend and cache that > + * instead. > + * > + * If a new ioend is created and cached, the old ioend is returned and queued > + * locally for submission once the entire page is processed or an error has been > + * detected. While ioends are submitted immediately after they are completed, > + * batching optimisations are provided by higher level block plugging. > + * > + * At the end of a writeback pass, there will be a cached ioend remaining on the > + * writepage context that the caller will need to submit. > + */ > +static int > +iomap_writepage_map(struct iomap_writepage_ctx *wpc, > + struct writeback_control *wbc, struct inode *inode, > + struct page *page, u64 end_offset) > +{ > + struct iomap_page *iop = to_iomap_page(page); > + struct iomap_ioend *ioend, *next; > + unsigned len = i_blocksize(inode); > + u64 file_offset; /* file offset of page */ > + int error = 0, count = 0, i; > + LIST_HEAD(submit_list); > + > + WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE && !iop); > + WARN_ON_ONCE(iop && atomic_read(&iop->write_count) != 0); > + > + /* > + * Walk through the page to find areas to write back. If we run off the > + * end of the current map or find the current map invalid, grab a new > + * one. > + */ > + for (i = 0, file_offset = page_offset(page); > + i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset; > + i++, file_offset += len) { > + if (iop && !test_bit(i, iop->uptodate)) > + continue; > + > + error = wpc->ops->map_blocks(wpc, inode, file_offset); > + if (error) > + break; > + if (wpc->iomap.type == IOMAP_HOLE) > + continue; > + iomap_add_to_ioend(inode, file_offset, page, iop, wpc, wbc, > + &submit_list); > + count++; > + } > + > + WARN_ON_ONCE(!wpc->ioend && !list_empty(&submit_list)); > + WARN_ON_ONCE(!PageLocked(page)); > + WARN_ON_ONCE(PageWriteback(page)); > + > + /* > + * On error, we have to fail the ioend here because we may have set > + * pages under writeback, we have to make sure we run IO completion to > + * mark the error state of the IO appropriately, so we can't cancel the > + * ioend directly here. That means we have to mark this page as under > + * writeback if we included any blocks from it in the ioend chain so > + * that completion treats it correctly. > + * > + * If we didn't include the page in the ioend, the on error we can > + * simply discard and unlock it as there are no other users of the page > + * now. The caller will still need to trigger submission of outstanding > + * ioends on the writepage context so they are treated correctly on > + * error. > + */ > + if (unlikely(error)) { > + if (!count) { > + wpc->ops->discard_page(page); > + ClearPageUptodate(page); > + unlock_page(page); > + goto done; > + } > + > + /* > + * If the page was not fully cleaned, we need to ensure that the > + * higher layers come back to it correctly. That means we need > + * to keep the page dirty, and for WB_SYNC_ALL writeback we need > + * to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed > + * so another attempt to write this page in this writeback sweep > + * will be made. > + */ > + set_page_writeback_keepwrite(page); > + } else { > + clear_page_dirty_for_io(page); > + set_page_writeback(page); > + } > + > + unlock_page(page); > + > + /* > + * Preserve the original error if there was one, otherwise catch > + * submission errors here and propagate into subsequent ioend > + * submissions. > + */ > + list_for_each_entry_safe(ioend, next, &submit_list, io_list) { > + int error2; > + > + list_del_init(&ioend->io_list); > + error2 = iomap_submit_ioend(wpc, ioend, error); > + if (error2 && !error) > + error = error2; > + } > + > + /* > + * We can end up here with no error and nothing to write only if we race > + * with a partial page truncate on a sub-page block sized filesystem. > + */ > + if (!count) > + end_page_writeback(page); > +done: > + mapping_set_error(page->mapping, error); > + return error; > +} > + > +/* > + * Write out a dirty page. > + * > + * For delalloc space on the page we need to allocate space and flush it. > + * For unwritten space on the page we need to start the conversion to > + * regular allocated space. > + */ > +static int > +iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) > +{ > + struct iomap_writepage_ctx *wpc = data; > + struct inode *inode = page->mapping->host; > + pgoff_t end_index; > + u64 end_offset; > + loff_t offset; > + > + /* > + * Refuse to write the page out if we are called from reclaim context. > + * > + * This avoids stack overflows when called from deeply used stacks in > + * random callers for direct reclaim or memcg reclaim. We explicitly > + * allow reclaim from kswapd as the stack usage there is relatively low. > + * > + * This should never happen except in the case of a VM regression so > + * warn about it. > + */ > + if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == > + PF_MEMALLOC)) > + goto redirty; > + > + /* > + * Given that we do not allow direct reclaim to call us, we should > + * never be called while in a filesystem transaction. > + */ > + if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) > + goto redirty; > + > + /* > + * Is this page beyond the end of the file? > + * > + * The page index is less than the end_index, adjust the end_offset > + * to the highest offset that this page should represent. > + * ----------------------------------------------------- > + * | file mapping | <EOF> | > + * ----------------------------------------------------- > + * | Page ... | Page N-2 | Page N-1 | Page N | | > + * ^--------------------------------^----------|-------- > + * | desired writeback range | see else | > + * ---------------------------------^------------------| > + */ > + offset = i_size_read(inode); > + end_index = offset >> PAGE_SHIFT; > + if (page->index < end_index) > + end_offset = (loff_t)(page->index + 1) << PAGE_SHIFT; > + else { > + /* > + * Check whether the page to write out is beyond or straddles > + * i_size or not. > + * ------------------------------------------------------- > + * | file mapping | <EOF> | > + * ------------------------------------------------------- > + * | Page ... | Page N-2 | Page N-1 | Page N | Beyond | > + * ^--------------------------------^-----------|--------- > + * | | Straddles | > + * ---------------------------------^-----------|--------| > + */ > + unsigned offset_into_page = offset & (PAGE_SIZE - 1); > + > + /* > + * Skip the page if it is fully outside i_size, e.g. due to a > + * truncate operation that is in progress. We must redirty the > + * page so that reclaim stops reclaiming it. Otherwise > + * iomap_vm_releasepage() is called on it and gets confused. > + * > + * Note that the end_index is unsigned long, it would overflow > + * if the given offset is greater than 16TB on 32-bit system > + * and if we do check the page is fully outside i_size or not > + * via "if (page->index >= end_index + 1)" as "end_index + 1" > + * will be evaluated to 0. Hence this page will be redirtied > + * and be written out repeatedly which would result in an > + * infinite loop, the user program that perform this operation > + * will hang. Instead, we can verify this situation by checking > + * if the page to write is totally beyond the i_size or if it's > + * offset is just equal to the EOF. > + */ > + if (page->index > end_index || > + (page->index == end_index && offset_into_page == 0)) > + goto redirty; > + > + /* > + * The page straddles i_size. It must be zeroed out on each > + * and every writepage invocation because it may be mmapped. > + * "A file is mapped in multiples of the page size. For a file > + * that is not a multiple of the page size, the remaining > + * memory is zeroed when mapped, and writes to that region are > + * not written out to the file." > + */ > + zero_user_segment(page, offset_into_page, PAGE_SIZE); > + > + /* Adjust the end_offset to the end of file */ > + end_offset = offset; > + } > + > + return iomap_writepage_map(wpc, wbc, inode, page, end_offset); > + > +redirty: > + redirty_page_for_writepage(wbc, page); > + unlock_page(page); > + return 0; > +} > + > +int > +iomap_writepage(struct page *page, struct writeback_control *wbc, > + struct iomap_writepage_ctx *wpc, > + const struct iomap_writeback_ops *ops) > +{ > + int ret; > + > + wpc->ops = ops; > + ret = iomap_do_writepage(page, wbc, wpc); > + if (!wpc->ioend) > + return ret; > + return iomap_submit_ioend(wpc, wpc->ioend, ret); > +} > +EXPORT_SYMBOL_GPL(iomap_writepage); > + > +int > +iomap_writepages(struct address_space *mapping, struct writeback_control *wbc, > + struct iomap_writepage_ctx *wpc, > + const struct iomap_writeback_ops *ops) > +{ > + int ret; > + > + wpc->ops = ops; > + ret = write_cache_pages(mapping, wbc, iomap_do_writepage, wpc); > + if (!wpc->ioend) > + return ret; > + return iomap_submit_ioend(wpc, wpc->ioend, ret); > +} > +EXPORT_SYMBOL_GPL(iomap_writepages); > + > +static int __init iomap_init(void) > +{ > + return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE), > + offsetof(struct iomap_ioend, io_inline_bio), > + BIOSET_NEED_BVECS); > +} > +fs_initcall(iomap_init); > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c > index d9a7a9e6b912..26b838aea2db 100644 > --- a/fs/xfs/xfs_aops.c > +++ b/fs/xfs/xfs_aops.c > @@ -23,16 +23,18 @@ > #include "xfs_reflink.h" > #include <linux/writeback.h> > > -/* > - * structure owned by writepages passed to individual writepage calls > - */ > struct xfs_writepage_ctx { > - struct iomap iomap; > + struct iomap_writepage_ctx ctx; > unsigned int data_seq; > unsigned int cow_seq; > - struct xfs_ioend *ioend; > }; > > +static inline struct xfs_writepage_ctx * > +XFS_WPC(struct iomap_writepage_ctx *ctx) > +{ > + return container_of(ctx, struct xfs_writepage_ctx, ctx); > +} > + > struct block_device * > xfs_find_bdev_for_inode( > struct inode *inode) > @@ -59,84 +61,10 @@ xfs_find_daxdev_for_inode( > return mp->m_ddev_targp->bt_daxdev; > } > > -static void > -xfs_finish_page_writeback( > - struct inode *inode, > - struct bio_vec *bvec, > - int error) > -{ > - struct iomap_page *iop = to_iomap_page(bvec->bv_page); > - > - if (error) { > - SetPageError(bvec->bv_page); > - mapping_set_error(inode->i_mapping, -EIO); > - } > - > - ASSERT(iop || i_blocksize(inode) == PAGE_SIZE); > - ASSERT(!iop || atomic_read(&iop->write_count) > 0); > - > - if (!iop || atomic_dec_and_test(&iop->write_count)) > - end_page_writeback(bvec->bv_page); > -} > - > -/* > - * We're now finished for good with this ioend structure. Update the page > - * state, release holds on bios, and finally free up memory. Do not use the > - * ioend after this. > - */ > -STATIC void > -xfs_destroy_ioend( > - struct xfs_ioend *ioend, > - int error) > -{ > - struct inode *inode = ioend->io_inode; > - struct bio *bio = &ioend->io_inline_bio; > - struct bio *last = ioend->io_bio, *next; > - u64 start = bio->bi_iter.bi_sector; > - bool quiet = bio_flagged(bio, BIO_QUIET); > - > - for (bio = &ioend->io_inline_bio; bio; bio = next) { > - struct bio_vec *bvec; > - struct bvec_iter_all iter_all; > - > - /* > - * For the last bio, bi_private points to the ioend, so we > - * need to explicitly end the iteration here. > - */ > - if (bio == last) > - next = NULL; > - else > - next = bio->bi_private; > - > - /* walk each page on bio, ending page IO on them */ > - bio_for_each_segment_all(bvec, bio, iter_all) > - xfs_finish_page_writeback(inode, bvec, error); > - bio_put(bio); > - } > - > - if (unlikely(error && !quiet)) { > - xfs_err_ratelimited(XFS_I(inode)->i_mount, > - "writeback error on sector %llu", start); > - } > -} > - > -static void > -xfs_destroy_ioends( > - struct xfs_ioend *ioend, > - int error) > -{ > - struct list_head tmp; > - > - list_replace_init(&ioend->io_list, &tmp); > - xfs_destroy_ioend(ioend, error); > - while ((ioend = list_pop(&tmp, struct xfs_ioend, io_list))) > - xfs_destroy_ioend(ioend, error); > -} > - > /* > * Fast and loose check if this write could update the on-disk inode size. > */ > -static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend) > +static inline bool xfs_ioend_is_append(struct iomap_ioend *ioend) > { > return ioend->io_offset + ioend->io_size > > XFS_I(ioend->io_inode)->i_d.di_size; > @@ -182,7 +110,7 @@ xfs_setfilesize( > */ > STATIC void > xfs_end_ioend( > - struct xfs_ioend *ioend) > + struct iomap_ioend *ioend) > { > unsigned int nofs_flag = memalloc_nofs_save(); > struct xfs_inode *ip = XFS_I(ioend->io_inode); > @@ -218,76 +146,10 @@ xfs_end_ioend( > if (!error && xfs_ioend_is_append(ioend)) > error = xfs_setfilesize(ip, offset, size); > done: > - xfs_destroy_ioends(ioend, error); > + iomap_finish_ioends(ioend, error); > memalloc_nofs_restore(nofs_flag); > } > > -/* > - * We can merge two adjacent ioends if they have the same set of work to do. > - */ > -static bool > -xfs_ioend_can_merge( > - struct xfs_ioend *ioend, > - struct xfs_ioend *next) > -{ > - if (ioend->io_bio->bi_status != next->io_bio->bi_status) > - return false; > - if ((ioend->io_flags & IOMAP_F_SHARED) ^ > - (next->io_flags & IOMAP_F_SHARED)) > - return false; > - if ((ioend->io_type == IOMAP_UNWRITTEN) ^ > - (next->io_type == IOMAP_UNWRITTEN)) > - return false; > - if (ioend->io_offset + ioend->io_size != next->io_offset) > - return false; > - return true; > -} > - > -/* Try to merge adjacent completions. */ > -STATIC void > -xfs_ioend_try_merge( > - struct xfs_ioend *ioend, > - struct list_head *more_ioends) > -{ > - struct xfs_ioend *next; > - > - INIT_LIST_HEAD(&ioend->io_list); > - > - while ((next = list_first_entry_or_null(more_ioends, struct xfs_ioend, > - io_list))) { > - if (!xfs_ioend_can_merge(ioend, next)) > - break; > - list_move_tail(&next->io_list, &ioend->io_list); > - ioend->io_size += next->io_size; > - } > -} > - > -/* list_sort compare function for ioends */ > -static int > -xfs_ioend_compare( > - void *priv, > - struct list_head *a, > - struct list_head *b) > -{ > - struct xfs_ioend *ia; > - struct xfs_ioend *ib; > - > - ia = container_of(a, struct xfs_ioend, io_list); > - ib = container_of(b, struct xfs_ioend, io_list); > - if (ia->io_offset < ib->io_offset) > - return -1; > - else if (ia->io_offset > ib->io_offset) > - return 1; > - return 0; > -} > - > -static void > -xfs_sort_ioends( > - struct list_head *ioend_list) > -{ > - list_sort(NULL, ioend_list, xfs_ioend_compare); > -} > - > /* Finish all pending io completions. */ > void > xfs_end_io( > @@ -295,7 +157,7 @@ xfs_end_io( > { > struct xfs_inode *ip = > container_of(work, struct xfs_inode, i_ioend_work); > - struct xfs_ioend *ioend; > + struct iomap_ioend *ioend; > struct list_head tmp; > unsigned long flags; > > @@ -303,9 +165,9 @@ xfs_end_io( > list_replace_init(&ip->i_ioend_list, &tmp); > spin_unlock_irqrestore(&ip->i_ioend_lock, flags); > > - xfs_sort_ioends(&tmp); > - while ((ioend = list_pop(&tmp, struct xfs_ioend, io_list))) { > - xfs_ioend_try_merge(ioend, &tmp); > + iomap_sort_ioends(&tmp); > + while ((ioend = list_pop(&tmp, struct iomap_ioend, io_list))) { > + iomap_ioend_try_merge(ioend, &tmp); > xfs_end_ioend(ioend); > } > } > @@ -314,7 +176,7 @@ STATIC void > xfs_end_bio( > struct bio *bio) > { > - struct xfs_ioend *ioend = bio->bi_private; > + struct iomap_ioend *ioend = bio->bi_private; > struct xfs_inode *ip = XFS_I(ioend->io_inode); > struct xfs_mount *mp = ip->i_mount; > unsigned long flags; > @@ -329,7 +191,7 @@ xfs_end_bio( > list_add_tail(&ioend->io_list, &ip->i_ioend_list); > spin_unlock_irqrestore(&ip->i_ioend_lock, flags); > } else > - xfs_destroy_ioend(ioend, blk_status_to_errno(bio->bi_status)); > + iomap_finish_ioend(ioend, blk_status_to_errno(bio->bi_status)); > } > > /* > @@ -338,7 +200,7 @@ xfs_end_bio( > */ > static bool > xfs_imap_valid( > - struct xfs_writepage_ctx *wpc, > + struct iomap_writepage_ctx *wpc, > struct xfs_inode *ip, > loff_t offset) > { > @@ -360,10 +222,10 @@ xfs_imap_valid( > * checked (and found nothing at this offset) could have added > * overlapping blocks. > */ > - if (wpc->data_seq != READ_ONCE(ip->i_df.if_seq)) > + if (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq)) > return false; > if (xfs_inode_has_cow_data(ip) && > - wpc->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) > + XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) > return false; > return true; > } > @@ -378,12 +240,18 @@ xfs_imap_valid( > */ > static int > xfs_convert_blocks( > - struct xfs_writepage_ctx *wpc, > + struct iomap_writepage_ctx *wpc, > struct xfs_inode *ip, > int whichfork, > loff_t offset) > { > int error; > + unsigned *seq; > + > + if (whichfork == XFS_COW_FORK) > + seq = &XFS_WPC(wpc)->cow_seq; > + else > + seq = &XFS_WPC(wpc)->data_seq; > > /* > * Attempt to allocate whatever delalloc extent currently backs offset > @@ -393,8 +261,7 @@ xfs_convert_blocks( > */ > do { > error = xfs_bmapi_convert_delalloc(ip, whichfork, offset, > - &wpc->iomap, whichfork == XFS_COW_FORK ? > - &wpc->cow_seq : &wpc->data_seq); > + &wpc->iomap, seq); > if (error) > return error; > } while (wpc->iomap.offset + wpc->iomap.length <= offset); > @@ -402,9 +269,9 @@ xfs_convert_blocks( > return 0; > } > > -STATIC int > +static int > xfs_map_blocks( > - struct xfs_writepage_ctx *wpc, > + struct iomap_writepage_ctx *wpc, > struct inode *inode, > loff_t offset) > { > @@ -460,7 +327,7 @@ xfs_map_blocks( > xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap)) > cow_fsb = imap.br_startoff; > if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) { > - wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq); > + XFS_WPC(wpc)->cow_seq = READ_ONCE(ip->i_cowfp->if_seq); > xfs_iunlock(ip, XFS_ILOCK_SHARED); > > whichfork = XFS_COW_FORK; > @@ -483,7 +350,7 @@ xfs_map_blocks( > */ > if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap)) > imap.br_startoff = end_fsb; /* fake a hole past EOF */ > - wpc->data_seq = READ_ONCE(ip->i_df.if_seq); > + XFS_WPC(wpc)->data_seq = READ_ONCE(ip->i_df.if_seq); > xfs_iunlock(ip, XFS_ILOCK_SHARED); > > /* landed in a hole or beyond EOF? */ > @@ -547,24 +414,9 @@ xfs_map_blocks( > return 0; > } > > -/* > - * Submit the bio for an ioend. We are passed an ioend with a bio attached to > - * it, and we submit that bio. The ioend may be used for multiple bio > - * submissions, so we only want to allocate an append transaction for the ioend > - * once. In the case of multiple bio submission, each bio will take an IO > - * reference to the ioend to ensure that the ioend completion is only done once > - * all bios have been submitted and the ioend is really done. > - * > - * If @status is non-zero, it means that we have a situation where some part of > - * the submission process has failed after we have marked paged for writeback > - * and unlocked them. In this situation, we need to fail the bio and ioend > - * rather than submit it to IO. This typically only happens on a filesystem > - * shutdown. > - */ > -STATIC int > +static int > xfs_submit_ioend( > - struct writeback_control *wbc, > - struct xfs_ioend *ioend, > + struct iomap_ioend *ioend, > int status) > { > /* Convert CoW extents to regular */ > @@ -584,118 +436,8 @@ xfs_submit_ioend( > memalloc_nofs_restore(nofs_flag); > } > > - ioend->io_bio->bi_private = ioend; > ioend->io_bio->bi_end_io = xfs_end_bio; > - > - /* > - * If we are failing the IO now, just mark the ioend with an > - * error and finish it. This will run IO completion immediately > - * as there is only one reference to the ioend at this point in > - * time. > - */ > - if (status) { > - ioend->io_bio->bi_status = errno_to_blk_status(status); > - bio_endio(ioend->io_bio); > - return status; > - } > - > - submit_bio(ioend->io_bio); > - return 0; > -} > - > -static struct xfs_ioend * > -xfs_alloc_ioend( > - struct inode *inode, > - struct xfs_writepage_ctx *wpc, > - xfs_off_t offset, > - sector_t sector, > - struct writeback_control *wbc) > -{ > - struct xfs_ioend *ioend; > - struct bio *bio; > - > - bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &xfs_ioend_bioset); > - bio_set_dev(bio, wpc->iomap.bdev); > - bio->bi_iter.bi_sector = sector; > - bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); > - bio->bi_write_hint = inode->i_write_hint; > - > - ioend = container_of(bio, struct xfs_ioend, io_inline_bio); > - INIT_LIST_HEAD(&ioend->io_list); > - ioend->io_type = wpc->iomap.type; > - ioend->io_flags = wpc->iomap.flags; > - ioend->io_inode = inode; > - ioend->io_size = 0; > - ioend->io_offset = offset; > - ioend->io_bio = bio; > - return ioend; > -} > - > -/* > - * Allocate a new bio, and chain the old bio to the new one. > - * > - * Note that we have to do perform the chaining in this unintuitive order > - * so that the bi_private linkage is set up in the right direction for the > - * traversal in xfs_destroy_ioend(). > - */ > -static struct bio * > -xfs_chain_bio( > - struct bio *prev) > -{ > - struct bio *new; > - > - new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES); > - bio_copy_dev(new, prev); > - new->bi_iter.bi_sector = bio_end_sector(prev); > - new->bi_opf = prev->bi_opf; > - new->bi_write_hint = prev->bi_write_hint; > - > - bio_chain(prev, new); > - bio_get(prev); /* for xfs_destroy_ioend */ > - submit_bio(prev); > - return new; > -} > - > -/* > - * Test to see if we have an existing ioend structure that we could append to > - * first, otherwise finish off the current ioend and start another. > - */ > -STATIC void > -xfs_add_to_ioend( > - struct inode *inode, > - xfs_off_t offset, > - struct page *page, > - struct iomap_page *iop, > - struct xfs_writepage_ctx *wpc, > - struct writeback_control *wbc, > - struct list_head *iolist) > -{ > - unsigned len = i_blocksize(inode); > - unsigned poff = offset & (PAGE_SIZE - 1); > - sector_t sector; > - > - sector = (wpc->iomap.addr + offset - wpc->iomap.offset) >> 9; > - > - if (!wpc->ioend || > - (wpc->iomap.flags & IOMAP_F_SHARED) != > - (wpc->ioend->io_flags & IOMAP_F_SHARED) || > - wpc->iomap.type != wpc->ioend->io_type || > - sector != bio_end_sector(wpc->ioend->io_bio) || > - offset != wpc->ioend->io_offset + wpc->ioend->io_size) { > - if (wpc->ioend) > - list_add(&wpc->ioend->io_list, iolist); > - wpc->ioend = xfs_alloc_ioend(inode, wpc, offset, sector, wbc); > - } > - > - if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) { > - if (iop) > - atomic_inc(&iop->write_count); > - if (bio_full(wpc->ioend->io_bio)) > - wpc->ioend->io_bio = xfs_chain_bio(wpc->ioend->io_bio); > - bio_add_page(wpc->ioend->io_bio, page, len, poff); > - } > - > - wpc->ioend->io_size += len; > + return status; > } > > STATIC void > @@ -719,8 +461,8 @@ xfs_vm_invalidatepage( > * transaction as there is no space left for block reservation (typically why we > * see a ENOSPC in writeback). > */ > -STATIC void > -xfs_aops_discard_page( > +static void > +xfs_discard_page( > struct page *page) > { > struct inode *inode = page->mapping->host; > @@ -745,243 +487,11 @@ xfs_aops_discard_page( > xfs_vm_invalidatepage(page, 0, PAGE_SIZE); > } > > -/* > - * We implement an immediate ioend submission policy here to avoid needing to > - * chain multiple ioends and hence nest mempool allocations which can violate > - * forward progress guarantees we need to provide. The current ioend we are > - * adding blocks to is cached on the writepage context, and if the new block > - * does not append to the cached ioend it will create a new ioend and cache that > - * instead. > - * > - * If a new ioend is created and cached, the old ioend is returned and queued > - * locally for submission once the entire page is processed or an error has been > - * detected. While ioends are submitted immediately after they are completed, > - * batching optimisations are provided by higher level block plugging. > - * > - * At the end of a writeback pass, there will be a cached ioend remaining on the > - * writepage context that the caller will need to submit. > - */ > -static int > -xfs_writepage_map( > - struct xfs_writepage_ctx *wpc, > - struct writeback_control *wbc, > - struct inode *inode, > - struct page *page, > - uint64_t end_offset) > -{ > - LIST_HEAD(submit_list); > - struct iomap_page *iop = to_iomap_page(page); > - unsigned len = i_blocksize(inode); > - struct xfs_ioend *ioend, *next; > - uint64_t file_offset; /* file offset of page */ > - int error = 0, count = 0, i; > - > - ASSERT(iop || i_blocksize(inode) == PAGE_SIZE); > - ASSERT(!iop || atomic_read(&iop->write_count) == 0); > - > - /* > - * Walk through the page to find areas to write back. If we run off the > - * end of the current map or find the current map invalid, grab a new > - * one. > - */ > - for (i = 0, file_offset = page_offset(page); > - i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset; > - i++, file_offset += len) { > - if (iop && !test_bit(i, iop->uptodate)) > - continue; > - > - error = xfs_map_blocks(wpc, inode, file_offset); > - if (error) > - break; > - if (wpc->iomap.type == IOMAP_HOLE) > - continue; > - xfs_add_to_ioend(inode, file_offset, page, iop, wpc, wbc, > - &submit_list); > - count++; > - } > - > - ASSERT(wpc->ioend || list_empty(&submit_list)); > - ASSERT(PageLocked(page)); > - ASSERT(!PageWriteback(page)); > - > - /* > - * On error, we have to fail the ioend here because we may have set > - * pages under writeback, we have to make sure we run IO completion to > - * mark the error state of the IO appropriately, so we can't cancel the > - * ioend directly here. That means we have to mark this page as under > - * writeback if we included any blocks from it in the ioend chain so > - * that completion treats it correctly. > - * > - * If we didn't include the page in the ioend, the on error we can > - * simply discard and unlock it as there are no other users of the page > - * now. The caller will still need to trigger submission of outstanding > - * ioends on the writepage context so they are treated correctly on > - * error. > - */ > - if (unlikely(error)) { > - if (!count) { > - xfs_aops_discard_page(page); > - ClearPageUptodate(page); > - unlock_page(page); > - goto done; > - } > - > - /* > - * If the page was not fully cleaned, we need to ensure that the > - * higher layers come back to it correctly. That means we need > - * to keep the page dirty, and for WB_SYNC_ALL writeback we need > - * to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed > - * so another attempt to write this page in this writeback sweep > - * will be made. > - */ > - set_page_writeback_keepwrite(page); > - } else { > - clear_page_dirty_for_io(page); > - set_page_writeback(page); > - } > - > - unlock_page(page); > - > - /* > - * Preserve the original error if there was one, otherwise catch > - * submission errors here and propagate into subsequent ioend > - * submissions. > - */ > - list_for_each_entry_safe(ioend, next, &submit_list, io_list) { > - int error2; > - > - list_del_init(&ioend->io_list); > - error2 = xfs_submit_ioend(wbc, ioend, error); > - if (error2 && !error) > - error = error2; > - } > - > - /* > - * We can end up here with no error and nothing to write only if we race > - * with a partial page truncate on a sub-page block sized filesystem. > - */ > - if (!count) > - end_page_writeback(page); > -done: > - mapping_set_error(page->mapping, error); > - return error; > -} > - > -/* > - * Write out a dirty page. > - * > - * For delalloc space on the page we need to allocate space and flush it. > - * For unwritten space on the page we need to start the conversion to > - * regular allocated space. > - */ > -STATIC int > -xfs_do_writepage( > - struct page *page, > - struct writeback_control *wbc, > - void *data) > -{ > - struct xfs_writepage_ctx *wpc = data; > - struct inode *inode = page->mapping->host; > - loff_t offset; > - uint64_t end_offset; > - pgoff_t end_index; > - > - trace_xfs_writepage(inode, page, 0, 0); > - > - /* > - * Refuse to write the page out if we are called from reclaim context. > - * > - * This avoids stack overflows when called from deeply used stacks in > - * random callers for direct reclaim or memcg reclaim. We explicitly > - * allow reclaim from kswapd as the stack usage there is relatively low. > - * > - * This should never happen except in the case of a VM regression so > - * warn about it. > - */ > - if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == > - PF_MEMALLOC)) > - goto redirty; > - > - /* > - * Given that we do not allow direct reclaim to call us, we should > - * never be called while in a filesystem transaction. > - */ > - if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) > - goto redirty; > - > - /* > - * Is this page beyond the end of the file? > - * > - * The page index is less than the end_index, adjust the end_offset > - * to the highest offset that this page should represent. > - * ----------------------------------------------------- > - * | file mapping | <EOF> | > - * ----------------------------------------------------- > - * | Page ... | Page N-2 | Page N-1 | Page N | | > - * ^--------------------------------^----------|-------- > - * | desired writeback range | see else | > - * ---------------------------------^------------------| > - */ > - offset = i_size_read(inode); > - end_index = offset >> PAGE_SHIFT; > - if (page->index < end_index) > - end_offset = (xfs_off_t)(page->index + 1) << PAGE_SHIFT; > - else { > - /* > - * Check whether the page to write out is beyond or straddles > - * i_size or not. > - * ------------------------------------------------------- > - * | file mapping | <EOF> | > - * ------------------------------------------------------- > - * | Page ... | Page N-2 | Page N-1 | Page N | Beyond | > - * ^--------------------------------^-----------|--------- > - * | | Straddles | > - * ---------------------------------^-----------|--------| > - */ > - unsigned offset_into_page = offset & (PAGE_SIZE - 1); > - > - /* > - * Skip the page if it is fully outside i_size, e.g. due to a > - * truncate operation that is in progress. We must redirty the > - * page so that reclaim stops reclaiming it. Otherwise > - * xfs_vm_releasepage() is called on it and gets confused. > - * > - * Note that the end_index is unsigned long, it would overflow > - * if the given offset is greater than 16TB on 32-bit system > - * and if we do check the page is fully outside i_size or not > - * via "if (page->index >= end_index + 1)" as "end_index + 1" > - * will be evaluated to 0. Hence this page will be redirtied > - * and be written out repeatedly which would result in an > - * infinite loop, the user program that perform this operation > - * will hang. Instead, we can verify this situation by checking > - * if the page to write is totally beyond the i_size or if it's > - * offset is just equal to the EOF. > - */ > - if (page->index > end_index || > - (page->index == end_index && offset_into_page == 0)) > - goto redirty; > - > - /* > - * The page straddles i_size. It must be zeroed out on each > - * and every writepage invocation because it may be mmapped. > - * "A file is mapped in multiples of the page size. For a file > - * that is not a multiple of the page size, the remaining > - * memory is zeroed when mapped, and writes to that region are > - * not written out to the file." > - */ > - zero_user_segment(page, offset_into_page, PAGE_SIZE); > - > - /* Adjust the end_offset to the end of file */ > - end_offset = offset; > - } > - > - return xfs_writepage_map(wpc, wbc, inode, page, end_offset); > - > -redirty: > - redirty_page_for_writepage(wbc, page); > - unlock_page(page); > - return 0; > -} > +static const struct iomap_writeback_ops xfs_writeback_ops = { > + .map_blocks = xfs_map_blocks, > + .submit_ioend = xfs_submit_ioend, > + .discard_page = xfs_discard_page, > +}; > > STATIC int > xfs_vm_writepage( > @@ -989,12 +499,8 @@ xfs_vm_writepage( > struct writeback_control *wbc) > { > struct xfs_writepage_ctx wpc = { }; > - int ret; > > - ret = xfs_do_writepage(page, wbc, &wpc); > - if (wpc.ioend) > - ret = xfs_submit_ioend(wbc, wpc.ioend, ret); > - return ret; > + return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops); > } > > STATIC int > @@ -1003,13 +509,9 @@ xfs_vm_writepages( > struct writeback_control *wbc) > { > struct xfs_writepage_ctx wpc = { }; > - int ret; > > xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); > - ret = write_cache_pages(mapping, wbc, xfs_do_writepage, &wpc); > - if (wpc.ioend) > - ret = xfs_submit_ioend(wbc, wpc.ioend, ret); > - return ret; > + return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops); > } > > STATIC int > diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h > index bf95837c59af..26a7772d4b81 100644 > --- a/fs/xfs/xfs_aops.h > +++ b/fs/xfs/xfs_aops.h > @@ -6,22 +6,6 @@ > #ifndef __XFS_AOPS_H__ > #define __XFS_AOPS_H__ > > -extern struct bio_set xfs_ioend_bioset; > - > -/* > - * Structure for buffered I/O completions. > - */ > -struct xfs_ioend { > - struct list_head io_list; /* next ioend in chain */ > - u16 io_type; > - u16 io_flags; > - struct inode *io_inode; /* file being written to */ > - size_t io_size; /* size of the extent */ > - xfs_off_t io_offset; /* offset in the file */ > - struct bio *io_bio; /* bio being built */ > - struct bio io_inline_bio; /* MUST BE LAST! */ > -}; > - > extern const struct address_space_operations xfs_address_space_operations; > extern const struct address_space_operations xfs_dax_aops; > > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c > index 594c119824cc..52b89e175bc5 100644 > --- a/fs/xfs/xfs_super.c > +++ b/fs/xfs/xfs_super.c > @@ -53,7 +53,6 @@ > #include <linux/parser.h> > > static const struct super_operations xfs_super_operations; > -struct bio_set xfs_ioend_bioset; > > static struct kset *xfs_kset; /* top-level xfs sysfs dir */ > #ifdef DEBUG > @@ -1870,15 +1869,10 @@ MODULE_ALIAS_FS("xfs"); > STATIC int __init > xfs_init_zones(void) > { > - if (bioset_init(&xfs_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE), > - offsetof(struct xfs_ioend, io_inline_bio), > - BIOSET_NEED_BVECS)) > - goto out; > - > xfs_log_ticket_zone = kmem_zone_init(sizeof(xlog_ticket_t), > "xfs_log_ticket"); > if (!xfs_log_ticket_zone) > - goto out_free_ioend_bioset; > + goto out; > > xfs_bmap_free_item_zone = kmem_zone_init( > sizeof(struct xfs_extent_free_item), > @@ -2013,8 +2007,6 @@ xfs_init_zones(void) > kmem_zone_destroy(xfs_bmap_free_item_zone); > out_destroy_log_ticket_zone: > kmem_zone_destroy(xfs_log_ticket_zone); > - out_free_ioend_bioset: > - bioset_exit(&xfs_ioend_bioset); > out: > return -ENOMEM; > } > @@ -2045,7 +2037,6 @@ xfs_destroy_zones(void) > kmem_zone_destroy(xfs_btree_cur_zone); > kmem_zone_destroy(xfs_bmap_free_item_zone); > kmem_zone_destroy(xfs_log_ticket_zone); > - bioset_exit(&xfs_ioend_bioset); > } > > STATIC int __init > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 2103b94cb1bf..e87f44810c53 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -4,6 +4,7 @@ > > #include <linux/atomic.h> > #include <linux/bitmap.h> > +#include <linux/blk_types.h> > #include <linux/mm.h> > #include <linux/types.h> > #include <linux/mm_types.h> > @@ -11,6 +12,7 @@ > struct address_space; > struct fiemap_extent_info; > struct inode; > +struct iomap_writepage_ctx; > struct iov_iter; > struct kiocb; > struct page; > @@ -165,6 +167,45 @@ loff_t iomap_seek_data(struct inode *inode, loff_t offset, > sector_t iomap_bmap(struct address_space *mapping, sector_t bno, > const struct iomap_ops *ops); > > +/* > + * Structure for writeback I/O completions. > + */ > +struct iomap_ioend { > + struct list_head io_list; /* next ioend in chain */ > + u16 io_type; > + u16 io_flags; > + struct inode *io_inode; /* file being written to */ > + size_t io_size; /* size of the extent */ > + loff_t io_offset; /* offset in the file */ > + struct bio *io_bio; /* bio being built */ > + struct bio io_inline_bio; /* MUST BE LAST! */ > +}; > + > +struct iomap_writeback_ops { > + int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode, > + loff_t offset); > + int (*submit_ioend)(struct iomap_ioend *ioend, int status); > + void (*discard_page)(struct page *page); > +}; > + > +struct iomap_writepage_ctx { > + struct iomap iomap; > + struct iomap_ioend *ioend; > + const struct iomap_writeback_ops *ops; > +}; > + > +void iomap_finish_ioend(struct iomap_ioend *ioend, int error); > +void iomap_finish_ioends(struct iomap_ioend *ioend, int error); > +void iomap_ioend_try_merge(struct iomap_ioend *ioend, > + struct list_head *more_ioends); > +void iomap_sort_ioends(struct list_head *ioend_list); > +int iomap_writepage(struct page *page, struct writeback_control *wbc, > + struct iomap_writepage_ctx *wpc, > + const struct iomap_writeback_ops *ops); > +int iomap_writepages(struct address_space *mapping, > + struct writeback_control *wbc, struct iomap_writepage_ctx *wpc, > + const struct iomap_writeback_ops *ops); > + > /* > * Flags for direct I/O ->end_io: > */ > -- > 2.20.1 >
On Mon, Jun 24, 2019 at 07:52:52AM +0200, Christoph Hellwig wrote: > Takes the xfs writeback code and move it to iomap.c. A new structure > with three methods is added as the abstraction from the generic > writeback code to the file system. These methods are used to map > blocks, submit an ioend, and cancel a page that encountered an error > before it was added to an ioend. > > Note that we temporarily lose the writepage tracing, but that will > be added back soon. I'm a little concerned this is going to limit what we can do with the XFS IO path because now we can't change this code without considering the direct impact on other filesystems. The QA burden of changing the XFS writeback code goes through the roof with this change (i.e. we can break multiple filesystems, not just XFS). The writepage code is one of the areas that, historically speaking, has one of the highest rates of modification in XFS - we've substantially reworked this code from top to bottom 4 or 5 times in a bit over ten years, and each time it's been removing abstraction layers and getting the writeback code closer to the internal XFS extent mapping infrastructure. This steps the other way - it adds abstraction to move the XFS code to be generic, and now we have to be concerned about how changes to the XFS IO path affects other filesystems. While I can see the desire to use this code in other filesystems, no other filesystem does COW or delayed allocation like XFS and this functionality is tightly tied into the iomap page writeback architecture. As such, I'm not convinced that a wholesale lifting of this code into the generic iomap code is going to make our life easier or better. The stuff we've already got in fs/iomap.c is largely uncontroversial and straight forward, but this writeback code is anything but straight forward..... Another issue this raises is that fs/iomap.c is already huge chunk of code with lots of different functionality in it. Adding another 500+ lines of new functionality to it doesn't make it any easier to navigate or find things. If we are going to move this writeback code to the generic iomap infrastructure, can we please split the iomap code up in to smaller files first? e.g. fs/iomap-dio.c for all the direct IO code, fs/iomap-pageio.c for all the page-based IO, fs/iomap.c for all the core functionality (like iomap_apply()) and fs/iomap-util.c for all the miscellaneous one-off functions like fiemap, etc? Cheers, Dave.
On Mon, Jun 24, 2019 at 08:46:01AM -0700, Darrick J. Wong wrote: > This looks like a straight code copy from fs/xfs/ into fs/iomap.c. > That's fine with me, but seeing as this file is now ~2700 lines long, > perhaps we should break this up among major functional lines? > > Looking at fs/iomap.c, I see... > > * Basic iomap iterator functions (~40 lines) > * Page cache management (readpage*, write, mkwrite) (~860 lines) > * Zeroing (~80 lines) > * FIEMAP and seek hole / seek data (~300 lines) > * directio (~500 lines) > * swapfiles (~170 lines) > * and now, page cache writeback (~520 lines) > > If I have spare time this week (ha ha) I'll see if I can break all this > up (as a separate patch series), so for this: Meh. Not sure I'm a fan of too fine grained splits like the one above. And ~3k lines is still pretty manageable. But yes, once it grows ã‚€ore it might be worth splitting a bit.
On Tue, Jun 25, 2019 at 09:43:04AM +1000, Dave Chinner wrote: > I'm a little concerned this is going to limit what we can do > with the XFS IO path because now we can't change this code without > considering the direct impact on other filesystems. The QA burden of > changing the XFS writeback code goes through the roof with this > change (i.e. we can break multiple filesystems, not just XFS). Going through the roof is a little exaggerated. Yes, it will be more testing overhead, but that is life in a world where we try to share code rather than duplicating it, which is pretty much a general kernel policy that has served us well. > The writepage code is one of the areas that, historically speaking, > has one of the highest rates of modification in XFS - we've > substantially reworked this code from top to bottom 4 or 5 times in > a bit over ten years, and each time it's been removing abstraction > layers and getting the writeback code closer to the internal XFS > extent mapping infrastructure. I don't think we had all that much churn. Yes, we've improved it a lot, but much of that was in response to core changes, and pretty much all of it benefits other users as well. And the more users we have for this infrastructure that more clout it has with core VM folks when we have to push back odd design decisions.
On Tue, Jun 25, 2019 at 12:10:20PM +0200, Christoph Hellwig wrote: > On Tue, Jun 25, 2019 at 09:43:04AM +1000, Dave Chinner wrote: > > I'm a little concerned this is going to limit what we can do > > with the XFS IO path because now we can't change this code without > > considering the direct impact on other filesystems. The QA burden of > > changing the XFS writeback code goes through the roof with this > > change (i.e. we can break multiple filesystems, not just XFS). > > Going through the roof is a little exaggerated. You've already mentioned two new users you want to add. I don't even have zone capable hardware here to test one of the users you are indicating will use this code, and I suspect that very few people do. That's a non-trivial increase in testing requirements for filesystem developers and distro QA departments who will want to change and/or validate this code path. > Yes, it will be more > testing overhead, but that is life in a world where we try to share > code rather than duplicating it, which is pretty much a general > kernel policy that has served us well. Yes, but we also need to acknowledge why we have re-implemented everything in fs/iomap.c - we haven't lifted code from XFS to do that - we've replaced existing generic code that didn't do what we needed and couldn't easily be modified to do what we needed because of all it's external dependencies. Indeed, integrating gfs2 into the existing generic iomap code has required quite a bit of munging and adding new code paths and so on. That's mostly been straight forward because it's just been adding flags and conditional code to the existing paths. The way we regularly rewrite sections of the XFS writeback code is a very different sort of modification, and one that will be much harder to do if we have to make those changes to generic code. i.e. shared code is good if it's simple and doesn't have a lot of external dependencies that restrict the type and scope of modifications that can be made easily. Shared code that is complex and comes from code that was tightly integrated with a specific subsystem architecture is going to carry all those architectural foilbles into the new "generic" code. Once it gets sufficient users it's going to end up with the same "we can't change this code" problems that we had with the existing IO path, and we'll go back to implementing our own writeback path.... > > The writepage code is one of the areas that, historically speaking, > > has one of the highest rates of modification in XFS - we've > > substantially reworked this code from top to bottom 4 or 5 times in > > a bit over ten years, and each time it's been removing abstraction > > layers and getting the writeback code closer to the internal XFS > > extent mapping infrastructure. > > I don't think we had all that much churn. We've had more churn over time to the writeback code than just about any other subsystem in XFS. It also represents a complete 180-degree flip on how we've been streamlining the writeback path in XFS over the past few years. We've been moving closer and closer to the generic writeback infrastructure as well as closer to the XFS inode extent tree. I've been planning on taking it even closer to the extent tree to give us lockless, modification range coherent extent map caching in this path (e.g. write() can add new delalloc extents without invalidating cached writeback maps). This patchset re-introduces the iomap abstraction over the bmbt - an abstraction we removed some time ago - and that makes these sorts of improvements much harder and more complex to implement.... IOWs, I'm not convinced that lifting this code out of XFS is the best long term plan for XFS or the iomap code here.... > Yes, we've improved it a > lot, but much of that was in response to core changes, and pretty much > all of it benefits other users as well. And the more users we have > for this infrastructure that more clout it has with core VM folks > when we have to push back odd design decisions. If we have to make stuff "generic" to be able to influence how other subsystems go about providing infrastructure to filesytsems, then our development community and processes are even more broken than I think they are. Developer communication and design influence are not problems we should be trying to fix with code. Cheers, Dave. -Dave.
On Fri, Jun 28, 2019 at 10:45:42AM +1000, Dave Chinner wrote: > You've already mentioned two new users you want to add. I don't even > have zone capable hardware here to test one of the users you are > indicating will use this code, and I suspect that very few people > do. That's a non-trivial increase in testing requirements for > filesystem developers and distro QA departments who will want to > change and/or validate this code path. Why do you assume you have to test it? Back when we shared generic_file_read with everyone you also didn't test odd change to it with every possible fs. If you change iomap.c, you'll test it with XFS, and Cc other maintainers so that they get a chance to also test it and comment on it, just like we do with other shared code in the kernel. > Indeed, integrating gfs2 into the existing generic iomap code has > required quite a bit of munging and adding new code paths and so on. > That's mostly been straight forward because it's just been adding > flags and conditional code to the existing paths. The way we > regularly rewrite sections of the XFS writeback code is a very > different sort of modification, and one that will be much harder to > do if we have to make those changes to generic code. As the person who has done a lot of the recent rewriting of the writeback code I disagree. Most of it has been do divorce is from leftovers of the buffer_head based sinle page at a time design from stone age. Very little is about XFS itself, most of it has been about not being stupid in a fairly generic way. And every since I got rid of buffer heads xfs_aops.c has been intimately tied into the iomap infrastructure, and I'd rather keep those details in one place. I.e. with this series now XFS doesn't even need to know about the details of the iomap_page structure and the uptodate bits. If for example I'd want to add sub-page dirty bits (which I don't if I can avoid it) I can handle this entirely in iomap now instead of spreading around iomap, xfs and duplicating the thing in every copy of the XFS code that would otherwise show up. > i.e. shared code is good if it's simple and doesn't have a lot of > external dependencies that restrict the type and scope of > modifications that can be made easily. Shared code that is complex > and comes from code that was tightly integrated with a specific > subsystem architecture is going to carry all those architectural > foilbles into the new "generic" code. Once it gets sufficient > users it's going to end up with the same "we can't change this code" > problems that we had with the existing IO path, and we'll go back to > implementing our own writeback path.... From the high level POV I agree with your stance. But the point is that the writeback code is not tightly integrated with xfs, and that is why I don't want it in XFS. It is on other other hand very tightly integrated with the iomap buffer read and write into pagecache code, which is why I want to keep it together with that. > I've been planning on taking it even closer to the extent tree to > give us lockless, modification range coherent extent map caching in > this path (e.g. write() can add new delalloc extents without > invalidating cached writeback maps). This patchset re-introduces > the iomap abstraction over the bmbt - an abstraction we removed some > time ago - and that makes these sorts of improvements much harder > and more complex to implement.... FYI, I had an earlier but not quite optimal implementation of lockless extent lookups using rcu updates in the btree. And at least for that scheme all the details stay 100% in XFS in the split code, as the abstraction between iomap and xfs is very clear and allows for that.
On Fri, Jun 28, 2019 at 10:45:42AM +1000, Dave Chinner wrote: > On Tue, Jun 25, 2019 at 12:10:20PM +0200, Christoph Hellwig wrote: > > On Tue, Jun 25, 2019 at 09:43:04AM +1000, Dave Chinner wrote: > > > I'm a little concerned this is going to limit what we can do > > > with the XFS IO path because now we can't change this code without > > > considering the direct impact on other filesystems. The QA burden of > > > changing the XFS writeback code goes through the roof with this > > > change (i.e. we can break multiple filesystems, not just XFS). > > > > Going through the roof is a little exaggerated. > > You've already mentioned two new users you want to add. I don't even > have zone capable hardware here to test one of the users you are > indicating will use this code, and I suspect that very few people > do. That's a non-trivial increase in testing requirements for > filesystem developers and distro QA departments who will want to > change and/or validate this code path. A side topic here: Looking towards the future of prosects here with regards to helping QA and developers with more confidence in API changes (kunit is one prospect we're evaluating)... If... we could somehow... codify what XFS *requires* from the API precisely... would that help alleviate concerns or bring confidence in the prospect of sharing code? Or is it simply an *impossibility* to address these concerns in question by codifying tests for the promised API? Ie, are the concerns something which could be addressed with strict testing on adherence to an API, or are the concerns *unknown* side dependencies which could not possibly be codified? As an example of the extent possible to codify API promise (although I beleive it was unintentional at first), see: http://lkml.kernel.org/r/20190626021744.GU19023@42.do-not-panic.com Luis
On Fri, Jun 28, 2019 at 07:33:20AM +0200, Christoph Hellwig wrote: > On Fri, Jun 28, 2019 at 10:45:42AM +1000, Dave Chinner wrote: > > You've already mentioned two new users you want to add. I don't even > > have zone capable hardware here to test one of the users you are > > indicating will use this code, and I suspect that very few people > > do. That's a non-trivial increase in testing requirements for > > filesystem developers and distro QA departments who will want to > > change and/or validate this code path. > > Why do you assume you have to test it? Back when we shared > generic_file_read with everyone you also didn't test odd change to > it with every possible fs. I'm not sure what function you are referring to here. Can you clarify? > If you change iomap.c, you'll test it > with XFS, and Cc other maintainers so that they get a chance to > also test it and comment on it, just like we do with other shared > code in the kernel. Which is why we've had problems with the generic code paths in the past and other filesystems just copy and paste then before making signficant modifications. e.g. both ext4 and btrfs re-implement write_cache_pages() rather than use the generic writeback code because they have slightly different requirements and those developers don't want to have to worry about other filesystems every time there is an internal filesystem change that affects their writeback constraints... That's kinda what I'm getting at here: writeback isn't being shared by any of the major filesystems for good reasons... > > Indeed, integrating gfs2 into the existing generic iomap code has > > required quite a bit of munging and adding new code paths and so on. > > That's mostly been straight forward because it's just been adding > > flags and conditional code to the existing paths. The way we > > regularly rewrite sections of the XFS writeback code is a very > > different sort of modification, and one that will be much harder to > > do if we have to make those changes to generic code. > > As the person who has done a lot of the recent rewriting of the > writeback code I disagree. Most of it has been do divorce is from > leftovers of the buffer_head based sinle page at a time design from > stone age. Very little is about XFS itself, most of it has been > about not being stupid in a fairly generic way. And every since > I got rid of buffer heads xfs_aops.c has been intimately tied ^^^^^^^^^^^^^^^^^^^^^^^^^ *cough* Getting rid of bufferheads in writeback was largely a result of work I did over a period of several years, thank you very much. Yes, work you did over the same time period also got us there, but it's not all your work. > into the iomap infrastructure, and I'd rather keep those details in > one place. I.e. with this series now XFS doesn't even need to know > about the details of the iomap_page structure and the uptodate > bits. If for example I'd want to add sub-page dirty bits (which I > don't if I can avoid it) I can handle this entirely in iomap now > instead of spreading around iomap, xfs and duplicating the thing > in every copy of the XFS code that would otherwise show up. Yes, I understand your motivations, I'm just not convinced that it is the right thing to do given the history of this code and the history of filesystem writeback code in general.... > > i.e. shared code is good if it's simple and doesn't have a lot of > > external dependencies that restrict the type and scope of > > modifications that can be made easily. Shared code that is complex > > and comes from code that was tightly integrated with a specific > > subsystem architecture is going to carry all those architectural > > foilbles into the new "generic" code. Once it gets sufficient > > users it's going to end up with the same "we can't change this code" > > problems that we had with the existing IO path, and we'll go back to > > implementing our own writeback path.... > > From the high level POV I agree with your stance. But the point is > that the writeback code is not tightly integrated with xfs, and that Except it is.... > is why I don't want it in XFS. It is on other other hand very > tightly integrated with the iomap buffer read and write into pagecache > code, which is why I want to keep it together with that. It's not tightly integrated into the iomap read side or page cache implementations. Writeback currently gets a dirty page, we look up a block map, we add it to/create a cached ioend/bio pair. There are four lines of code in the entire XFS writeback code path that interact with iomap specific state, and that's the grand total of interactions needed to support block size < page size writeback. IOWs, we barely interact with the page cache or page/iomap state at all in writeback anymore - we just write whole pages based on the current inode extent map state. Yes, the writepage context, the ioends and the extent map structures we use to implement this can be made generic, but it's all the other details that are the problem here. e.g. If we have an error, we have to do very XFS specific things (like punching out delalloc ranges) and so the generic iomap code has a hook for doing this XFS specific thing when necessary. e.g. XFS requires COW fork manipulation on ioend submission (xfs_submit_ioend() calls xfs_reflink_convert_cow()) and this has some nasty memory allocation requirements (potential deadlock situation). So the generic code has a hook for this XFS specific functionality, even though no other filesystem if likely to ever need this. And this is something we've been discussion getting rid of from the XFS writeback path. i.e. reworking how we do all the COW fork interactions in writeback. So some of these hooks are suspect even now, and we're already trying to work out how to re-work the XFS writeback path to sort out problems we have with it. That's the point I'm trying to make - the whole "generic" iomap writeback API proposal is based around exactly the functionality XFS - and only XFS - requires at this point in time. There are no other users of this API and until there are, we've got no idea how generic this functionality really is and just how much overhead making fundamental changes to the XFS writeback code are going to entail in future. IOWs, before we go any further I'd really like to see how the other proposed users of this functionality fit into the code and how generic these XFS hooks are and what new hooks they require to implement their specific functionality... Cheers, Dave.
On Mon, Jul 01, 2019 at 10:08:59AM +1000, Dave Chinner wrote: > > Why do you assume you have to test it? Back when we shared > > generic_file_read with everyone you also didn't test odd change to > > it with every possible fs. > > I'm not sure what function you are referring to here. Can you > clarify? Right now it is generic_file_read_iter(), but before iter it was generic_file_readv, generic_file_read, etc. > > If you change iomap.c, you'll test it > > with XFS, and Cc other maintainers so that they get a chance to > > also test it and comment on it, just like we do with other shared > > code in the kernel. > > Which is why we've had problems with the generic code paths in the > past and other filesystems just copy and paste then before making > signficant modifications. e.g. both ext4 and btrfs re-implement > write_cache_pages() rather than use the generic writeback code > because they have slightly different requirements and those > developers don't want to have to worry about other filesystems every > time there is an internal filesystem change that affects their > writeback constraints... > > That's kinda what I'm getting at here: writeback isn't being shared > by any of the major filesystems for good reasons... I very fundamentally disagree. It is not shared for a bad reasons, and that is people not understanding the mess that the buffer head based code is, and not wanting to understand it. So they come up with their own piecemeal "improvements" for it making the situation worse. Writeback is fundamentally not fs specific in any way. Different file system might use different optional features like unwrittent extents, delalloc, data checksums, but once they implement them the behavior should be uniform. And I'd much rather fix this than going down the copy an paste and slightly tweak it while fucking up something else route. > > stone age. Very little is about XFS itself, most of it has been > > about not being stupid in a fairly generic way. And every since > > I got rid of buffer heads xfs_aops.c has been intimately tied > ^^^^^^^^^^^^^^^^^^^^^^^^^ > > *cough* > > Getting rid of bufferheads in writeback was largely a result of work > I did over a period of several years, thank you very much. Yes, work > you did over the same time period also got us there, but it's not > all your work. Sorry Dave - this isn't avoud taking credit of past work. But ever since I finally got rid of bufferhads and introduced struct iomap_page we have this intimate tie up, which is the point here. > e.g. XFS requires COW fork manipulation on ioend submission > (xfs_submit_ioend() calls xfs_reflink_convert_cow()) and this has > some nasty memory allocation requirements (potential deadlock > situation). So the generic code has a hook for this XFS specific > functionality, even though no other filesystem if likely to ever > need this. And this is something we've been discussion getting rid > of from the XFS writeback path. i.e. reworking how we do all > the COW fork interactions in writeback. So some of these hooks are > suspect even now, and we're already trying to work out how to > re-work the XFS writeback path to sort out problems we have with it. Every file system that writes out of place will need some sort of hook here with the same issue, no matter if they call it COW fork or manipulate some all integrated data structure like btrfs. Moreover btrfs will also have to deal with their data checksum in exactly this place. > That's the point I'm trying to make - the whole "generic" iomap > writeback API proposal is based around exactly the functionality XFS > - and only XFS - requires at this point in time. There are no other > users of this API and until there are, we've got no idea how > generic this functionality really is and just how much overhead > making fundamental changes to the XFS writeback code are going to > entail in future. No, it is based around generalizing what we have in xfs so that we can use it elsewhere. With zonefs and gfs2 as the prime users initially, and other like btrfs hopefully to not far away.
On Mon, Jul 01, 2019 at 08:43:33AM +0200, Christoph Hellwig wrote: > On Mon, Jul 01, 2019 at 10:08:59AM +1000, Dave Chinner wrote: > > > Why do you assume you have to test it? Back when we shared > > > generic_file_read with everyone you also didn't test odd change to > > > it with every possible fs. > > > > I'm not sure what function you are referring to here. Can you > > clarify? > > Right now it is generic_file_read_iter(), but before iter it was > generic_file_readv, generic_file_read, etc. This generic code never came from XFS, so I'm still not sure what you are refering to here? Some pointers to commits would help me remember. :/ > > > If you change iomap.c, you'll test it > > > with XFS, and Cc other maintainers so that they get a chance to > > > also test it and comment on it, just like we do with other shared > > > code in the kernel. > > > > Which is why we've had problems with the generic code paths in the > > past and other filesystems just copy and paste then before making > > signficant modifications. e.g. both ext4 and btrfs re-implement > > write_cache_pages() rather than use the generic writeback code > > because they have slightly different requirements and those > > developers don't want to have to worry about other filesystems every > > time there is an internal filesystem change that affects their > > writeback constraints... > > > > That's kinda what I'm getting at here: writeback isn't being shared > > by any of the major filesystems for good reasons... > > I very fundamentally disagree. It is not shared for a bad reasons, > and that is people not understanding the mess that the buffer head > based code is, and not wanting to understand it. The problem with heavily shared code is that it requires far more expertise, knowledge, capability and time to modify it. The code essentially ossifies, because changing something fundamental risks breaking other stuff that nobody actually understands anymore and is unwilling to risk changing. That's not a problem with bufferheads - that's a problem of widely shared code that has been slowly hacked to pieces to "fix' random problems that show up from different users of the shared code. When the shared code ossifies like this, the only way to make progress is to either copy it and do whatever you need privately, or re-implement it completely. ext4 and btrfs have taken the route of "copy and modify privately", whereas XFS has taken the "re-implement it completely" path. We're now starting down the "share the XFS re-implementation" and we're slowly adding more complexity to the iomap code to handle the different things each filesystem that is converted needs. With each new fs adding their own little quirks, it gets harder to make significant modifications without unknowingly breaking something in some other filesystem. It takes highly capable developers to make serious modifications across highly shared code and the reality is that there are very few of them around. most developers simply aren't capable of taking on such a task, especially given that they see capable, experienced developers who won't even try because of past experiences akin to a game of Running Man(*).... Shared code is good, up to the point where the sharing gets so complex that even people with the capability are not willing to touch/fix the code. That's what happened to bufferheads and it's a pattern repeated across lots of kernel infrastructure code. Just because you can handle these modifications doesn't mean everyone else can or even wants to. > And I'd much rather fix this than going down the copy an paste and > slightly tweak it while fucking up something else route. The copy-n-paste is a result of developers who have little knowledge of things outside their domain of interest/expertise making the sane decision to minimise risk of breaking something they know nothing about. From an individual subsystem perspective, that's a -good decision- to make, and that's the point I was trying to make. You see that as a bad decision, because you equating "shared code" with "high quality" code. The reality is that shared code is often poor quality because people get too scared to touch it. That's exactly the situation I don't want us to get stuck with, and why I want to see how multiple implementations of this abstracted writeback path change what we have now before we start moving code about... i.e. I'm not saying "we shouldn't do this", I'm just saying that "we should do this because shared code is good" fundamentally conflicts with the fact we've just re-implemented a bunch of stuff because the *shared code was really bad*. And taking the same path that lead to really bad shared code (i.e. organic growth without planning or design) is likely to end up in the same place.... Cheers, Dave. (*) https://www.imdb.com/title/tt0093894/ "A wrongly convicted man must try to survive a public execution gauntlet staged as a game show."
On Fri, Jun 28, 2019 at 3:28 PM Luis Chamberlain <mcgrof@kernel.org> wrote: > > On Fri, Jun 28, 2019 at 10:45:42AM +1000, Dave Chinner wrote: > > On Tue, Jun 25, 2019 at 12:10:20PM +0200, Christoph Hellwig wrote: > > > On Tue, Jun 25, 2019 at 09:43:04AM +1000, Dave Chinner wrote: > > > > I'm a little concerned this is going to limit what we can do > > > > with the XFS IO path because now we can't change this code without > > > > considering the direct impact on other filesystems. The QA burden of > > > > changing the XFS writeback code goes through the roof with this > > > > change (i.e. we can break multiple filesystems, not just XFS). > > > > > > Going through the roof is a little exaggerated. > > > > You've already mentioned two new users you want to add. I don't even > > have zone capable hardware here to test one of the users you are > > indicating will use this code, and I suspect that very few people > > do. That's a non-trivial increase in testing requirements for > > filesystem developers and distro QA departments who will want to > > change and/or validate this code path. > > A side topic here: > > Looking towards the future of prosects here with regards to helping QA > and developers with more confidence in API changes (kunit is one > prospect we're evaluating)... > > If... we could somehow... codify what XFS *requires* from the API > precisely... would that help alleviate concerns or bring confidence in > the prospect of sharing code? > > Or is it simply an *impossibility* to address these concerns in question by > codifying tests for the promised API? > > Ie, are the concerns something which could be addressed with strict > testing on adherence to an API, or are the concerns *unknown* side > dependencies which could not possibly be codified? Thanks for pointing this out, Luis. This is a really important distinction. In the former case, I think as has become apparent in your example below; KUnit has a strong potential to be able to formally specify API behavior and guarantee compliance. However, as you point out there are many *unknown* dependencies which always have a way of sneaking into API informal specifications. I have some colleagues working on this problem for unknown server API dependencies; nevertheless, to my knowledge this is an unsolved problem. One partial solution I have seen is to put a system in place to record live traffic so that it can be later replayed in a test environment. Another partial solution is a modified form of fuzz testing similar to what Haskell's QuickCheck[1] does, which basically attempts to allow users to specify the kinds of data they expect to handle in such a way that QuickCheck is able to generate random data, pass it into the API, and verify the results satisfy the contract. I actually wrote a prototype of this for KUnit, but haven't publicly shared it yet since I thought it was kind of an out there idea (plus KUnit was pretty far away from being merged at the time). Still, a QuickCheck style test will always have the problem that the contract will likely underspecify things, and if not, the test may still never run long enough to cover all interesting cases. I have heard of attempts to solve this problem by combining the two prior approaches in novel ways (like using a QuckCheck style specification to mutate real recorded data). Anyway, sorry for the tangent, but I would be really interested to know whether you think the problem is more of the just testing the formally specified contract or the problem lies in unknown dependencies that Luis mentioned, and in either case whether you would find any of these ideas useful. > As an example of the extent possible to codify API promise (although > I beleive it was unintentional at first), see: > > http://lkml.kernel.org/r/20190626021744.GU19023@42.do-not-panic.com [1] http://www.cse.chalmers.se/~rjmh/QuickCheck/manual.html Cheers!
diff --git a/fs/iomap.c b/fs/iomap.c index 23ef63fd1669..72a1b622e634 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2010 Red Hat, Inc. - * Copyright (c) 2016-2018 Christoph Hellwig. + * Copyright (c) 2016-2019 Christoph Hellwig. */ #include <linux/module.h> #include <linux/compiler.h> @@ -12,6 +12,7 @@ #include <linux/migrate.h> #include <linux/mm.h> #include <linux/mm_inline.h> +#include <linux/list_sort.h> #include <linux/swap.h> #include <linux/pagemap.h> #include <linux/pagevec.h> @@ -25,6 +26,8 @@ #include "internal.h" +static struct bio_set iomap_ioend_bioset; + /* * Execute a iomap write on a segment of the mapping that spans a * contiguous range of pages that have identical block mapping state. @@ -2192,3 +2195,519 @@ iomap_bmap(struct address_space *mapping, sector_t bno, return bno; } EXPORT_SYMBOL_GPL(iomap_bmap); + +static void +iomap_finish_page_writeback(struct inode *inode, struct bio_vec *bvec, + int error) +{ + struct iomap_page *iop = to_iomap_page(bvec->bv_page); + + if (error) { + SetPageError(bvec->bv_page); + mapping_set_error(inode->i_mapping, -EIO); + } + + WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE && !iop); + WARN_ON_ONCE(iop && atomic_read(&iop->write_count) <= 0); + + if (!iop || atomic_dec_and_test(&iop->write_count)) + end_page_writeback(bvec->bv_page); +} + +/* + * We're now finished for good with this ioend structure. Update the page + * state, release holds on bios, and finally free up memory. Do not use the + * ioend after this. + */ +void +iomap_finish_ioend(struct iomap_ioend *ioend, int error) +{ + struct inode *inode = ioend->io_inode; + struct bio *bio = &ioend->io_inline_bio; + struct bio *last = ioend->io_bio, *next; + u64 start = bio->bi_iter.bi_sector; + bool quiet = bio_flagged(bio, BIO_QUIET); + + for (bio = &ioend->io_inline_bio; bio; bio = next) { + struct bio_vec *bvec; + struct bvec_iter_all iter_all; + + /* + * For the last bio, bi_private points to the ioend, so we + * need to explicitly end the iteration here. + */ + if (bio == last) + next = NULL; + else + next = bio->bi_private; + + /* walk each page on bio, ending page IO on them */ + bio_for_each_segment_all(bvec, bio, iter_all) + iomap_finish_page_writeback(inode, bvec, error); + bio_put(bio); + } + + if (unlikely(error && !quiet)) { + printk_ratelimited(KERN_ERR + "%s: writeback error on sector %llu", + inode->i_sb->s_id, start); + } +} +EXPORT_SYMBOL_GPL(iomap_finish_ioend); + +void +iomap_finish_ioends(struct iomap_ioend *ioend, int error) +{ + struct list_head tmp; + + list_replace_init(&ioend->io_list, &tmp); + iomap_finish_ioend(ioend, error); + while ((ioend = list_pop(&tmp, struct iomap_ioend, io_list))) + iomap_finish_ioend(ioend, error); +} +EXPORT_SYMBOL_GPL(iomap_finish_ioends); + +/* + * We can merge two adjacent ioends if they have the same set of work to do. + */ +static bool +iomap_ioend_can_merge(struct iomap_ioend *ioend, struct iomap_ioend *next) +{ + if (ioend->io_bio->bi_status != next->io_bio->bi_status) + return false; + if ((ioend->io_flags & IOMAP_F_SHARED) ^ + (next->io_flags & IOMAP_F_SHARED)) + return false; + if ((ioend->io_type == IOMAP_UNWRITTEN) ^ + (next->io_type == IOMAP_UNWRITTEN)) + return false; + if (ioend->io_offset + ioend->io_size != next->io_offset) + return false; + return true; +} + +void +iomap_ioend_try_merge(struct iomap_ioend *ioend, struct list_head *more_ioends) +{ + struct iomap_ioend *next; + + INIT_LIST_HEAD(&ioend->io_list); + + while ((next = list_first_entry_or_null(more_ioends, struct iomap_ioend, + io_list))) { + if (!iomap_ioend_can_merge(ioend, next)) + break; + list_move_tail(&next->io_list, &ioend->io_list); + ioend->io_size += next->io_size; + } +} +EXPORT_SYMBOL_GPL(iomap_ioend_try_merge); + +static int +iomap_ioend_compare(void *priv, struct list_head *a, struct list_head *b) +{ + struct iomap_ioend *ia, *ib; + + ia = container_of(a, struct iomap_ioend, io_list); + ib = container_of(b, struct iomap_ioend, io_list); + if (ia->io_offset < ib->io_offset) + return -1; + else if (ia->io_offset > ib->io_offset) + return 1; + return 0; +} + +void +iomap_sort_ioends(struct list_head *ioend_list) +{ + list_sort(NULL, ioend_list, iomap_ioend_compare); +} +EXPORT_SYMBOL_GPL(iomap_sort_ioends); + +/* + * Submit the bio for an ioend. We are passed an ioend with a bio attached to + * it, and we submit that bio. The ioend may be used for multiple bio + * submissions, so we only want to allocate an append transaction for the ioend + * once. In the case of multiple bio submission, each bio will take an IO + * reference to the ioend to ensure that the ioend completion is only done once + * all bios have been submitted and the ioend is really done. + * + * If @error is non-zero, it means that we have a situation where some part of + * the submission process has failed after we have marked paged for writeback + * and unlocked them. In this situation, we need to fail the bio and ioend + * rather than submit it to IO. This typically only happens on a filesystem + * shutdown. + */ +static int +iomap_submit_ioend(struct iomap_writepage_ctx *wpc, struct iomap_ioend *ioend, + int error) +{ + /* + * If we are failing the IO now, just mark the ioend with an error and + * finish it. This will run IO completion immediately as there is only + * one reference to the ioend at this point in time. + */ + ioend->io_bio->bi_private = ioend; + error = wpc->ops->submit_ioend(ioend, error); + if (error) { + ioend->io_bio->bi_status = errno_to_blk_status(error); + bio_endio(ioend->io_bio); + return error; + } + + submit_bio(ioend->io_bio); + return 0; +} + +static struct iomap_ioend * +iomap_alloc_ioend(struct inode *inode, struct iomap_writepage_ctx *wpc, + loff_t offset, sector_t sector, struct writeback_control *wbc) +{ + struct iomap_ioend *ioend; + struct bio *bio; + + bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &iomap_ioend_bioset); + bio_set_dev(bio, wpc->iomap.bdev); + bio->bi_iter.bi_sector = sector; + bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); + bio->bi_write_hint = inode->i_write_hint; + + ioend = container_of(bio, struct iomap_ioend, io_inline_bio); + INIT_LIST_HEAD(&ioend->io_list); + ioend->io_type = wpc->iomap.type; + ioend->io_flags = wpc->iomap.flags; + ioend->io_inode = inode; + ioend->io_size = 0; + ioend->io_offset = offset; + ioend->io_bio = bio; + return ioend; +} + +/* + * Allocate a new bio, and chain the old bio to the new one. + * + * Note that we have to do perform the chaining in this unintuitive order + * so that the bi_private linkage is set up in the right direction for the + * traversal in iomap_finish_ioend(). + */ +static struct bio * +iomap_chain_bio(struct bio *prev) +{ + struct bio *new; + + new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES); + bio_copy_dev(new, prev); + new->bi_iter.bi_sector = bio_end_sector(prev); + new->bi_opf = prev->bi_opf; + new->bi_write_hint = prev->bi_write_hint; + + bio_chain(prev, new); + bio_get(prev); /* for iomap_finish_ioend */ + submit_bio(prev); + return new; +} + +/* + * Test to see if we have an existing ioend structure that we could append to + * first, otherwise finish off the current ioend and start another. + */ +static void +iomap_add_to_ioend(struct inode *inode, loff_t offset, struct page *page, + struct iomap_page *iop, struct iomap_writepage_ctx *wpc, + struct writeback_control *wbc, struct list_head *iolist) +{ + unsigned len = i_blocksize(inode); + unsigned poff = offset & (PAGE_SIZE - 1); + sector_t sector = iomap_sector(&wpc->iomap, offset); + + if (!wpc->ioend || + (wpc->iomap.flags & IOMAP_F_SHARED) != + (wpc->ioend->io_flags & IOMAP_F_SHARED) || + wpc->iomap.type != wpc->ioend->io_type || + sector != bio_end_sector(wpc->ioend->io_bio) || + offset != wpc->ioend->io_offset + wpc->ioend->io_size) { + if (wpc->ioend) + list_add(&wpc->ioend->io_list, iolist); + wpc->ioend = iomap_alloc_ioend(inode, wpc, offset, sector, wbc); + } + + if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) { + if (iop) + atomic_inc(&iop->write_count); + if (bio_full(wpc->ioend->io_bio)) { + wpc->ioend->io_bio = + iomap_chain_bio(wpc->ioend->io_bio); + } + bio_add_page(wpc->ioend->io_bio, page, len, poff); + } + + wpc->ioend->io_size += len; +} + +/* + * We implement an immediate ioend submission policy here to avoid needing to + * chain multiple ioends and hence nest mempool allocations which can violate + * forward progress guarantees we need to provide. The current ioend we are + * adding blocks to is cached on the writepage context, and if the new block + * does not append to the cached ioend it will create a new ioend and cache that + * instead. + * + * If a new ioend is created and cached, the old ioend is returned and queued + * locally for submission once the entire page is processed or an error has been + * detected. While ioends are submitted immediately after they are completed, + * batching optimisations are provided by higher level block plugging. + * + * At the end of a writeback pass, there will be a cached ioend remaining on the + * writepage context that the caller will need to submit. + */ +static int +iomap_writepage_map(struct iomap_writepage_ctx *wpc, + struct writeback_control *wbc, struct inode *inode, + struct page *page, u64 end_offset) +{ + struct iomap_page *iop = to_iomap_page(page); + struct iomap_ioend *ioend, *next; + unsigned len = i_blocksize(inode); + u64 file_offset; /* file offset of page */ + int error = 0, count = 0, i; + LIST_HEAD(submit_list); + + WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE && !iop); + WARN_ON_ONCE(iop && atomic_read(&iop->write_count) != 0); + + /* + * Walk through the page to find areas to write back. If we run off the + * end of the current map or find the current map invalid, grab a new + * one. + */ + for (i = 0, file_offset = page_offset(page); + i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset; + i++, file_offset += len) { + if (iop && !test_bit(i, iop->uptodate)) + continue; + + error = wpc->ops->map_blocks(wpc, inode, file_offset); + if (error) + break; + if (wpc->iomap.type == IOMAP_HOLE) + continue; + iomap_add_to_ioend(inode, file_offset, page, iop, wpc, wbc, + &submit_list); + count++; + } + + WARN_ON_ONCE(!wpc->ioend && !list_empty(&submit_list)); + WARN_ON_ONCE(!PageLocked(page)); + WARN_ON_ONCE(PageWriteback(page)); + + /* + * On error, we have to fail the ioend here because we may have set + * pages under writeback, we have to make sure we run IO completion to + * mark the error state of the IO appropriately, so we can't cancel the + * ioend directly here. That means we have to mark this page as under + * writeback if we included any blocks from it in the ioend chain so + * that completion treats it correctly. + * + * If we didn't include the page in the ioend, the on error we can + * simply discard and unlock it as there are no other users of the page + * now. The caller will still need to trigger submission of outstanding + * ioends on the writepage context so they are treated correctly on + * error. + */ + if (unlikely(error)) { + if (!count) { + wpc->ops->discard_page(page); + ClearPageUptodate(page); + unlock_page(page); + goto done; + } + + /* + * If the page was not fully cleaned, we need to ensure that the + * higher layers come back to it correctly. That means we need + * to keep the page dirty, and for WB_SYNC_ALL writeback we need + * to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed + * so another attempt to write this page in this writeback sweep + * will be made. + */ + set_page_writeback_keepwrite(page); + } else { + clear_page_dirty_for_io(page); + set_page_writeback(page); + } + + unlock_page(page); + + /* + * Preserve the original error if there was one, otherwise catch + * submission errors here and propagate into subsequent ioend + * submissions. + */ + list_for_each_entry_safe(ioend, next, &submit_list, io_list) { + int error2; + + list_del_init(&ioend->io_list); + error2 = iomap_submit_ioend(wpc, ioend, error); + if (error2 && !error) + error = error2; + } + + /* + * We can end up here with no error and nothing to write only if we race + * with a partial page truncate on a sub-page block sized filesystem. + */ + if (!count) + end_page_writeback(page); +done: + mapping_set_error(page->mapping, error); + return error; +} + +/* + * Write out a dirty page. + * + * For delalloc space on the page we need to allocate space and flush it. + * For unwritten space on the page we need to start the conversion to + * regular allocated space. + */ +static int +iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) +{ + struct iomap_writepage_ctx *wpc = data; + struct inode *inode = page->mapping->host; + pgoff_t end_index; + u64 end_offset; + loff_t offset; + + /* + * Refuse to write the page out if we are called from reclaim context. + * + * This avoids stack overflows when called from deeply used stacks in + * random callers for direct reclaim or memcg reclaim. We explicitly + * allow reclaim from kswapd as the stack usage there is relatively low. + * + * This should never happen except in the case of a VM regression so + * warn about it. + */ + if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == + PF_MEMALLOC)) + goto redirty; + + /* + * Given that we do not allow direct reclaim to call us, we should + * never be called while in a filesystem transaction. + */ + if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) + goto redirty; + + /* + * Is this page beyond the end of the file? + * + * The page index is less than the end_index, adjust the end_offset + * to the highest offset that this page should represent. + * ----------------------------------------------------- + * | file mapping | <EOF> | + * ----------------------------------------------------- + * | Page ... | Page N-2 | Page N-1 | Page N | | + * ^--------------------------------^----------|-------- + * | desired writeback range | see else | + * ---------------------------------^------------------| + */ + offset = i_size_read(inode); + end_index = offset >> PAGE_SHIFT; + if (page->index < end_index) + end_offset = (loff_t)(page->index + 1) << PAGE_SHIFT; + else { + /* + * Check whether the page to write out is beyond or straddles + * i_size or not. + * ------------------------------------------------------- + * | file mapping | <EOF> | + * ------------------------------------------------------- + * | Page ... | Page N-2 | Page N-1 | Page N | Beyond | + * ^--------------------------------^-----------|--------- + * | | Straddles | + * ---------------------------------^-----------|--------| + */ + unsigned offset_into_page = offset & (PAGE_SIZE - 1); + + /* + * Skip the page if it is fully outside i_size, e.g. due to a + * truncate operation that is in progress. We must redirty the + * page so that reclaim stops reclaiming it. Otherwise + * iomap_vm_releasepage() is called on it and gets confused. + * + * Note that the end_index is unsigned long, it would overflow + * if the given offset is greater than 16TB on 32-bit system + * and if we do check the page is fully outside i_size or not + * via "if (page->index >= end_index + 1)" as "end_index + 1" + * will be evaluated to 0. Hence this page will be redirtied + * and be written out repeatedly which would result in an + * infinite loop, the user program that perform this operation + * will hang. Instead, we can verify this situation by checking + * if the page to write is totally beyond the i_size or if it's + * offset is just equal to the EOF. + */ + if (page->index > end_index || + (page->index == end_index && offset_into_page == 0)) + goto redirty; + + /* + * The page straddles i_size. It must be zeroed out on each + * and every writepage invocation because it may be mmapped. + * "A file is mapped in multiples of the page size. For a file + * that is not a multiple of the page size, the remaining + * memory is zeroed when mapped, and writes to that region are + * not written out to the file." + */ + zero_user_segment(page, offset_into_page, PAGE_SIZE); + + /* Adjust the end_offset to the end of file */ + end_offset = offset; + } + + return iomap_writepage_map(wpc, wbc, inode, page, end_offset); + +redirty: + redirty_page_for_writepage(wbc, page); + unlock_page(page); + return 0; +} + +int +iomap_writepage(struct page *page, struct writeback_control *wbc, + struct iomap_writepage_ctx *wpc, + const struct iomap_writeback_ops *ops) +{ + int ret; + + wpc->ops = ops; + ret = iomap_do_writepage(page, wbc, wpc); + if (!wpc->ioend) + return ret; + return iomap_submit_ioend(wpc, wpc->ioend, ret); +} +EXPORT_SYMBOL_GPL(iomap_writepage); + +int +iomap_writepages(struct address_space *mapping, struct writeback_control *wbc, + struct iomap_writepage_ctx *wpc, + const struct iomap_writeback_ops *ops) +{ + int ret; + + wpc->ops = ops; + ret = write_cache_pages(mapping, wbc, iomap_do_writepage, wpc); + if (!wpc->ioend) + return ret; + return iomap_submit_ioend(wpc, wpc->ioend, ret); +} +EXPORT_SYMBOL_GPL(iomap_writepages); + +static int __init iomap_init(void) +{ + return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE), + offsetof(struct iomap_ioend, io_inline_bio), + BIOSET_NEED_BVECS); +} +fs_initcall(iomap_init); diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index d9a7a9e6b912..26b838aea2db 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -23,16 +23,18 @@ #include "xfs_reflink.h" #include <linux/writeback.h> -/* - * structure owned by writepages passed to individual writepage calls - */ struct xfs_writepage_ctx { - struct iomap iomap; + struct iomap_writepage_ctx ctx; unsigned int data_seq; unsigned int cow_seq; - struct xfs_ioend *ioend; }; +static inline struct xfs_writepage_ctx * +XFS_WPC(struct iomap_writepage_ctx *ctx) +{ + return container_of(ctx, struct xfs_writepage_ctx, ctx); +} + struct block_device * xfs_find_bdev_for_inode( struct inode *inode) @@ -59,84 +61,10 @@ xfs_find_daxdev_for_inode( return mp->m_ddev_targp->bt_daxdev; } -static void -xfs_finish_page_writeback( - struct inode *inode, - struct bio_vec *bvec, - int error) -{ - struct iomap_page *iop = to_iomap_page(bvec->bv_page); - - if (error) { - SetPageError(bvec->bv_page); - mapping_set_error(inode->i_mapping, -EIO); - } - - ASSERT(iop || i_blocksize(inode) == PAGE_SIZE); - ASSERT(!iop || atomic_read(&iop->write_count) > 0); - - if (!iop || atomic_dec_and_test(&iop->write_count)) - end_page_writeback(bvec->bv_page); -} - -/* - * We're now finished for good with this ioend structure. Update the page - * state, release holds on bios, and finally free up memory. Do not use the - * ioend after this. - */ -STATIC void -xfs_destroy_ioend( - struct xfs_ioend *ioend, - int error) -{ - struct inode *inode = ioend->io_inode; - struct bio *bio = &ioend->io_inline_bio; - struct bio *last = ioend->io_bio, *next; - u64 start = bio->bi_iter.bi_sector; - bool quiet = bio_flagged(bio, BIO_QUIET); - - for (bio = &ioend->io_inline_bio; bio; bio = next) { - struct bio_vec *bvec; - struct bvec_iter_all iter_all; - - /* - * For the last bio, bi_private points to the ioend, so we - * need to explicitly end the iteration here. - */ - if (bio == last) - next = NULL; - else - next = bio->bi_private; - - /* walk each page on bio, ending page IO on them */ - bio_for_each_segment_all(bvec, bio, iter_all) - xfs_finish_page_writeback(inode, bvec, error); - bio_put(bio); - } - - if (unlikely(error && !quiet)) { - xfs_err_ratelimited(XFS_I(inode)->i_mount, - "writeback error on sector %llu", start); - } -} - -static void -xfs_destroy_ioends( - struct xfs_ioend *ioend, - int error) -{ - struct list_head tmp; - - list_replace_init(&ioend->io_list, &tmp); - xfs_destroy_ioend(ioend, error); - while ((ioend = list_pop(&tmp, struct xfs_ioend, io_list))) - xfs_destroy_ioend(ioend, error); -} - /* * Fast and loose check if this write could update the on-disk inode size. */ -static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend) +static inline bool xfs_ioend_is_append(struct iomap_ioend *ioend) { return ioend->io_offset + ioend->io_size > XFS_I(ioend->io_inode)->i_d.di_size; @@ -182,7 +110,7 @@ xfs_setfilesize( */ STATIC void xfs_end_ioend( - struct xfs_ioend *ioend) + struct iomap_ioend *ioend) { unsigned int nofs_flag = memalloc_nofs_save(); struct xfs_inode *ip = XFS_I(ioend->io_inode); @@ -218,76 +146,10 @@ xfs_end_ioend( if (!error && xfs_ioend_is_append(ioend)) error = xfs_setfilesize(ip, offset, size); done: - xfs_destroy_ioends(ioend, error); + iomap_finish_ioends(ioend, error); memalloc_nofs_restore(nofs_flag); } -/* - * We can merge two adjacent ioends if they have the same set of work to do. - */ -static bool -xfs_ioend_can_merge( - struct xfs_ioend *ioend, - struct xfs_ioend *next) -{ - if (ioend->io_bio->bi_status != next->io_bio->bi_status) - return false; - if ((ioend->io_flags & IOMAP_F_SHARED) ^ - (next->io_flags & IOMAP_F_SHARED)) - return false; - if ((ioend->io_type == IOMAP_UNWRITTEN) ^ - (next->io_type == IOMAP_UNWRITTEN)) - return false; - if (ioend->io_offset + ioend->io_size != next->io_offset) - return false; - return true; -} - -/* Try to merge adjacent completions. */ -STATIC void -xfs_ioend_try_merge( - struct xfs_ioend *ioend, - struct list_head *more_ioends) -{ - struct xfs_ioend *next; - - INIT_LIST_HEAD(&ioend->io_list); - - while ((next = list_first_entry_or_null(more_ioends, struct xfs_ioend, - io_list))) { - if (!xfs_ioend_can_merge(ioend, next)) - break; - list_move_tail(&next->io_list, &ioend->io_list); - ioend->io_size += next->io_size; - } -} - -/* list_sort compare function for ioends */ -static int -xfs_ioend_compare( - void *priv, - struct list_head *a, - struct list_head *b) -{ - struct xfs_ioend *ia; - struct xfs_ioend *ib; - - ia = container_of(a, struct xfs_ioend, io_list); - ib = container_of(b, struct xfs_ioend, io_list); - if (ia->io_offset < ib->io_offset) - return -1; - else if (ia->io_offset > ib->io_offset) - return 1; - return 0; -} - -static void -xfs_sort_ioends( - struct list_head *ioend_list) -{ - list_sort(NULL, ioend_list, xfs_ioend_compare); -} - /* Finish all pending io completions. */ void xfs_end_io( @@ -295,7 +157,7 @@ xfs_end_io( { struct xfs_inode *ip = container_of(work, struct xfs_inode, i_ioend_work); - struct xfs_ioend *ioend; + struct iomap_ioend *ioend; struct list_head tmp; unsigned long flags; @@ -303,9 +165,9 @@ xfs_end_io( list_replace_init(&ip->i_ioend_list, &tmp); spin_unlock_irqrestore(&ip->i_ioend_lock, flags); - xfs_sort_ioends(&tmp); - while ((ioend = list_pop(&tmp, struct xfs_ioend, io_list))) { - xfs_ioend_try_merge(ioend, &tmp); + iomap_sort_ioends(&tmp); + while ((ioend = list_pop(&tmp, struct iomap_ioend, io_list))) { + iomap_ioend_try_merge(ioend, &tmp); xfs_end_ioend(ioend); } } @@ -314,7 +176,7 @@ STATIC void xfs_end_bio( struct bio *bio) { - struct xfs_ioend *ioend = bio->bi_private; + struct iomap_ioend *ioend = bio->bi_private; struct xfs_inode *ip = XFS_I(ioend->io_inode); struct xfs_mount *mp = ip->i_mount; unsigned long flags; @@ -329,7 +191,7 @@ xfs_end_bio( list_add_tail(&ioend->io_list, &ip->i_ioend_list); spin_unlock_irqrestore(&ip->i_ioend_lock, flags); } else - xfs_destroy_ioend(ioend, blk_status_to_errno(bio->bi_status)); + iomap_finish_ioend(ioend, blk_status_to_errno(bio->bi_status)); } /* @@ -338,7 +200,7 @@ xfs_end_bio( */ static bool xfs_imap_valid( - struct xfs_writepage_ctx *wpc, + struct iomap_writepage_ctx *wpc, struct xfs_inode *ip, loff_t offset) { @@ -360,10 +222,10 @@ xfs_imap_valid( * checked (and found nothing at this offset) could have added * overlapping blocks. */ - if (wpc->data_seq != READ_ONCE(ip->i_df.if_seq)) + if (XFS_WPC(wpc)->data_seq != READ_ONCE(ip->i_df.if_seq)) return false; if (xfs_inode_has_cow_data(ip) && - wpc->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) + XFS_WPC(wpc)->cow_seq != READ_ONCE(ip->i_cowfp->if_seq)) return false; return true; } @@ -378,12 +240,18 @@ xfs_imap_valid( */ static int xfs_convert_blocks( - struct xfs_writepage_ctx *wpc, + struct iomap_writepage_ctx *wpc, struct xfs_inode *ip, int whichfork, loff_t offset) { int error; + unsigned *seq; + + if (whichfork == XFS_COW_FORK) + seq = &XFS_WPC(wpc)->cow_seq; + else + seq = &XFS_WPC(wpc)->data_seq; /* * Attempt to allocate whatever delalloc extent currently backs offset @@ -393,8 +261,7 @@ xfs_convert_blocks( */ do { error = xfs_bmapi_convert_delalloc(ip, whichfork, offset, - &wpc->iomap, whichfork == XFS_COW_FORK ? - &wpc->cow_seq : &wpc->data_seq); + &wpc->iomap, seq); if (error) return error; } while (wpc->iomap.offset + wpc->iomap.length <= offset); @@ -402,9 +269,9 @@ xfs_convert_blocks( return 0; } -STATIC int +static int xfs_map_blocks( - struct xfs_writepage_ctx *wpc, + struct iomap_writepage_ctx *wpc, struct inode *inode, loff_t offset) { @@ -460,7 +327,7 @@ xfs_map_blocks( xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap)) cow_fsb = imap.br_startoff; if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) { - wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq); + XFS_WPC(wpc)->cow_seq = READ_ONCE(ip->i_cowfp->if_seq); xfs_iunlock(ip, XFS_ILOCK_SHARED); whichfork = XFS_COW_FORK; @@ -483,7 +350,7 @@ xfs_map_blocks( */ if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap)) imap.br_startoff = end_fsb; /* fake a hole past EOF */ - wpc->data_seq = READ_ONCE(ip->i_df.if_seq); + XFS_WPC(wpc)->data_seq = READ_ONCE(ip->i_df.if_seq); xfs_iunlock(ip, XFS_ILOCK_SHARED); /* landed in a hole or beyond EOF? */ @@ -547,24 +414,9 @@ xfs_map_blocks( return 0; } -/* - * Submit the bio for an ioend. We are passed an ioend with a bio attached to - * it, and we submit that bio. The ioend may be used for multiple bio - * submissions, so we only want to allocate an append transaction for the ioend - * once. In the case of multiple bio submission, each bio will take an IO - * reference to the ioend to ensure that the ioend completion is only done once - * all bios have been submitted and the ioend is really done. - * - * If @status is non-zero, it means that we have a situation where some part of - * the submission process has failed after we have marked paged for writeback - * and unlocked them. In this situation, we need to fail the bio and ioend - * rather than submit it to IO. This typically only happens on a filesystem - * shutdown. - */ -STATIC int +static int xfs_submit_ioend( - struct writeback_control *wbc, - struct xfs_ioend *ioend, + struct iomap_ioend *ioend, int status) { /* Convert CoW extents to regular */ @@ -584,118 +436,8 @@ xfs_submit_ioend( memalloc_nofs_restore(nofs_flag); } - ioend->io_bio->bi_private = ioend; ioend->io_bio->bi_end_io = xfs_end_bio; - - /* - * If we are failing the IO now, just mark the ioend with an - * error and finish it. This will run IO completion immediately - * as there is only one reference to the ioend at this point in - * time. - */ - if (status) { - ioend->io_bio->bi_status = errno_to_blk_status(status); - bio_endio(ioend->io_bio); - return status; - } - - submit_bio(ioend->io_bio); - return 0; -} - -static struct xfs_ioend * -xfs_alloc_ioend( - struct inode *inode, - struct xfs_writepage_ctx *wpc, - xfs_off_t offset, - sector_t sector, - struct writeback_control *wbc) -{ - struct xfs_ioend *ioend; - struct bio *bio; - - bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &xfs_ioend_bioset); - bio_set_dev(bio, wpc->iomap.bdev); - bio->bi_iter.bi_sector = sector; - bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc); - bio->bi_write_hint = inode->i_write_hint; - - ioend = container_of(bio, struct xfs_ioend, io_inline_bio); - INIT_LIST_HEAD(&ioend->io_list); - ioend->io_type = wpc->iomap.type; - ioend->io_flags = wpc->iomap.flags; - ioend->io_inode = inode; - ioend->io_size = 0; - ioend->io_offset = offset; - ioend->io_bio = bio; - return ioend; -} - -/* - * Allocate a new bio, and chain the old bio to the new one. - * - * Note that we have to do perform the chaining in this unintuitive order - * so that the bi_private linkage is set up in the right direction for the - * traversal in xfs_destroy_ioend(). - */ -static struct bio * -xfs_chain_bio( - struct bio *prev) -{ - struct bio *new; - - new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES); - bio_copy_dev(new, prev); - new->bi_iter.bi_sector = bio_end_sector(prev); - new->bi_opf = prev->bi_opf; - new->bi_write_hint = prev->bi_write_hint; - - bio_chain(prev, new); - bio_get(prev); /* for xfs_destroy_ioend */ - submit_bio(prev); - return new; -} - -/* - * Test to see if we have an existing ioend structure that we could append to - * first, otherwise finish off the current ioend and start another. - */ -STATIC void -xfs_add_to_ioend( - struct inode *inode, - xfs_off_t offset, - struct page *page, - struct iomap_page *iop, - struct xfs_writepage_ctx *wpc, - struct writeback_control *wbc, - struct list_head *iolist) -{ - unsigned len = i_blocksize(inode); - unsigned poff = offset & (PAGE_SIZE - 1); - sector_t sector; - - sector = (wpc->iomap.addr + offset - wpc->iomap.offset) >> 9; - - if (!wpc->ioend || - (wpc->iomap.flags & IOMAP_F_SHARED) != - (wpc->ioend->io_flags & IOMAP_F_SHARED) || - wpc->iomap.type != wpc->ioend->io_type || - sector != bio_end_sector(wpc->ioend->io_bio) || - offset != wpc->ioend->io_offset + wpc->ioend->io_size) { - if (wpc->ioend) - list_add(&wpc->ioend->io_list, iolist); - wpc->ioend = xfs_alloc_ioend(inode, wpc, offset, sector, wbc); - } - - if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff, true)) { - if (iop) - atomic_inc(&iop->write_count); - if (bio_full(wpc->ioend->io_bio)) - wpc->ioend->io_bio = xfs_chain_bio(wpc->ioend->io_bio); - bio_add_page(wpc->ioend->io_bio, page, len, poff); - } - - wpc->ioend->io_size += len; + return status; } STATIC void @@ -719,8 +461,8 @@ xfs_vm_invalidatepage( * transaction as there is no space left for block reservation (typically why we * see a ENOSPC in writeback). */ -STATIC void -xfs_aops_discard_page( +static void +xfs_discard_page( struct page *page) { struct inode *inode = page->mapping->host; @@ -745,243 +487,11 @@ xfs_aops_discard_page( xfs_vm_invalidatepage(page, 0, PAGE_SIZE); } -/* - * We implement an immediate ioend submission policy here to avoid needing to - * chain multiple ioends and hence nest mempool allocations which can violate - * forward progress guarantees we need to provide. The current ioend we are - * adding blocks to is cached on the writepage context, and if the new block - * does not append to the cached ioend it will create a new ioend and cache that - * instead. - * - * If a new ioend is created and cached, the old ioend is returned and queued - * locally for submission once the entire page is processed or an error has been - * detected. While ioends are submitted immediately after they are completed, - * batching optimisations are provided by higher level block plugging. - * - * At the end of a writeback pass, there will be a cached ioend remaining on the - * writepage context that the caller will need to submit. - */ -static int -xfs_writepage_map( - struct xfs_writepage_ctx *wpc, - struct writeback_control *wbc, - struct inode *inode, - struct page *page, - uint64_t end_offset) -{ - LIST_HEAD(submit_list); - struct iomap_page *iop = to_iomap_page(page); - unsigned len = i_blocksize(inode); - struct xfs_ioend *ioend, *next; - uint64_t file_offset; /* file offset of page */ - int error = 0, count = 0, i; - - ASSERT(iop || i_blocksize(inode) == PAGE_SIZE); - ASSERT(!iop || atomic_read(&iop->write_count) == 0); - - /* - * Walk through the page to find areas to write back. If we run off the - * end of the current map or find the current map invalid, grab a new - * one. - */ - for (i = 0, file_offset = page_offset(page); - i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset; - i++, file_offset += len) { - if (iop && !test_bit(i, iop->uptodate)) - continue; - - error = xfs_map_blocks(wpc, inode, file_offset); - if (error) - break; - if (wpc->iomap.type == IOMAP_HOLE) - continue; - xfs_add_to_ioend(inode, file_offset, page, iop, wpc, wbc, - &submit_list); - count++; - } - - ASSERT(wpc->ioend || list_empty(&submit_list)); - ASSERT(PageLocked(page)); - ASSERT(!PageWriteback(page)); - - /* - * On error, we have to fail the ioend here because we may have set - * pages under writeback, we have to make sure we run IO completion to - * mark the error state of the IO appropriately, so we can't cancel the - * ioend directly here. That means we have to mark this page as under - * writeback if we included any blocks from it in the ioend chain so - * that completion treats it correctly. - * - * If we didn't include the page in the ioend, the on error we can - * simply discard and unlock it as there are no other users of the page - * now. The caller will still need to trigger submission of outstanding - * ioends on the writepage context so they are treated correctly on - * error. - */ - if (unlikely(error)) { - if (!count) { - xfs_aops_discard_page(page); - ClearPageUptodate(page); - unlock_page(page); - goto done; - } - - /* - * If the page was not fully cleaned, we need to ensure that the - * higher layers come back to it correctly. That means we need - * to keep the page dirty, and for WB_SYNC_ALL writeback we need - * to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed - * so another attempt to write this page in this writeback sweep - * will be made. - */ - set_page_writeback_keepwrite(page); - } else { - clear_page_dirty_for_io(page); - set_page_writeback(page); - } - - unlock_page(page); - - /* - * Preserve the original error if there was one, otherwise catch - * submission errors here and propagate into subsequent ioend - * submissions. - */ - list_for_each_entry_safe(ioend, next, &submit_list, io_list) { - int error2; - - list_del_init(&ioend->io_list); - error2 = xfs_submit_ioend(wbc, ioend, error); - if (error2 && !error) - error = error2; - } - - /* - * We can end up here with no error and nothing to write only if we race - * with a partial page truncate on a sub-page block sized filesystem. - */ - if (!count) - end_page_writeback(page); -done: - mapping_set_error(page->mapping, error); - return error; -} - -/* - * Write out a dirty page. - * - * For delalloc space on the page we need to allocate space and flush it. - * For unwritten space on the page we need to start the conversion to - * regular allocated space. - */ -STATIC int -xfs_do_writepage( - struct page *page, - struct writeback_control *wbc, - void *data) -{ - struct xfs_writepage_ctx *wpc = data; - struct inode *inode = page->mapping->host; - loff_t offset; - uint64_t end_offset; - pgoff_t end_index; - - trace_xfs_writepage(inode, page, 0, 0); - - /* - * Refuse to write the page out if we are called from reclaim context. - * - * This avoids stack overflows when called from deeply used stacks in - * random callers for direct reclaim or memcg reclaim. We explicitly - * allow reclaim from kswapd as the stack usage there is relatively low. - * - * This should never happen except in the case of a VM regression so - * warn about it. - */ - if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == - PF_MEMALLOC)) - goto redirty; - - /* - * Given that we do not allow direct reclaim to call us, we should - * never be called while in a filesystem transaction. - */ - if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) - goto redirty; - - /* - * Is this page beyond the end of the file? - * - * The page index is less than the end_index, adjust the end_offset - * to the highest offset that this page should represent. - * ----------------------------------------------------- - * | file mapping | <EOF> | - * ----------------------------------------------------- - * | Page ... | Page N-2 | Page N-1 | Page N | | - * ^--------------------------------^----------|-------- - * | desired writeback range | see else | - * ---------------------------------^------------------| - */ - offset = i_size_read(inode); - end_index = offset >> PAGE_SHIFT; - if (page->index < end_index) - end_offset = (xfs_off_t)(page->index + 1) << PAGE_SHIFT; - else { - /* - * Check whether the page to write out is beyond or straddles - * i_size or not. - * ------------------------------------------------------- - * | file mapping | <EOF> | - * ------------------------------------------------------- - * | Page ... | Page N-2 | Page N-1 | Page N | Beyond | - * ^--------------------------------^-----------|--------- - * | | Straddles | - * ---------------------------------^-----------|--------| - */ - unsigned offset_into_page = offset & (PAGE_SIZE - 1); - - /* - * Skip the page if it is fully outside i_size, e.g. due to a - * truncate operation that is in progress. We must redirty the - * page so that reclaim stops reclaiming it. Otherwise - * xfs_vm_releasepage() is called on it and gets confused. - * - * Note that the end_index is unsigned long, it would overflow - * if the given offset is greater than 16TB on 32-bit system - * and if we do check the page is fully outside i_size or not - * via "if (page->index >= end_index + 1)" as "end_index + 1" - * will be evaluated to 0. Hence this page will be redirtied - * and be written out repeatedly which would result in an - * infinite loop, the user program that perform this operation - * will hang. Instead, we can verify this situation by checking - * if the page to write is totally beyond the i_size or if it's - * offset is just equal to the EOF. - */ - if (page->index > end_index || - (page->index == end_index && offset_into_page == 0)) - goto redirty; - - /* - * The page straddles i_size. It must be zeroed out on each - * and every writepage invocation because it may be mmapped. - * "A file is mapped in multiples of the page size. For a file - * that is not a multiple of the page size, the remaining - * memory is zeroed when mapped, and writes to that region are - * not written out to the file." - */ - zero_user_segment(page, offset_into_page, PAGE_SIZE); - - /* Adjust the end_offset to the end of file */ - end_offset = offset; - } - - return xfs_writepage_map(wpc, wbc, inode, page, end_offset); - -redirty: - redirty_page_for_writepage(wbc, page); - unlock_page(page); - return 0; -} +static const struct iomap_writeback_ops xfs_writeback_ops = { + .map_blocks = xfs_map_blocks, + .submit_ioend = xfs_submit_ioend, + .discard_page = xfs_discard_page, +}; STATIC int xfs_vm_writepage( @@ -989,12 +499,8 @@ xfs_vm_writepage( struct writeback_control *wbc) { struct xfs_writepage_ctx wpc = { }; - int ret; - ret = xfs_do_writepage(page, wbc, &wpc); - if (wpc.ioend) - ret = xfs_submit_ioend(wbc, wpc.ioend, ret); - return ret; + return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops); } STATIC int @@ -1003,13 +509,9 @@ xfs_vm_writepages( struct writeback_control *wbc) { struct xfs_writepage_ctx wpc = { }; - int ret; xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); - ret = write_cache_pages(mapping, wbc, xfs_do_writepage, &wpc); - if (wpc.ioend) - ret = xfs_submit_ioend(wbc, wpc.ioend, ret); - return ret; + return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops); } STATIC int diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h index bf95837c59af..26a7772d4b81 100644 --- a/fs/xfs/xfs_aops.h +++ b/fs/xfs/xfs_aops.h @@ -6,22 +6,6 @@ #ifndef __XFS_AOPS_H__ #define __XFS_AOPS_H__ -extern struct bio_set xfs_ioend_bioset; - -/* - * Structure for buffered I/O completions. - */ -struct xfs_ioend { - struct list_head io_list; /* next ioend in chain */ - u16 io_type; - u16 io_flags; - struct inode *io_inode; /* file being written to */ - size_t io_size; /* size of the extent */ - xfs_off_t io_offset; /* offset in the file */ - struct bio *io_bio; /* bio being built */ - struct bio io_inline_bio; /* MUST BE LAST! */ -}; - extern const struct address_space_operations xfs_address_space_operations; extern const struct address_space_operations xfs_dax_aops; diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 594c119824cc..52b89e175bc5 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -53,7 +53,6 @@ #include <linux/parser.h> static const struct super_operations xfs_super_operations; -struct bio_set xfs_ioend_bioset; static struct kset *xfs_kset; /* top-level xfs sysfs dir */ #ifdef DEBUG @@ -1870,15 +1869,10 @@ MODULE_ALIAS_FS("xfs"); STATIC int __init xfs_init_zones(void) { - if (bioset_init(&xfs_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE), - offsetof(struct xfs_ioend, io_inline_bio), - BIOSET_NEED_BVECS)) - goto out; - xfs_log_ticket_zone = kmem_zone_init(sizeof(xlog_ticket_t), "xfs_log_ticket"); if (!xfs_log_ticket_zone) - goto out_free_ioend_bioset; + goto out; xfs_bmap_free_item_zone = kmem_zone_init( sizeof(struct xfs_extent_free_item), @@ -2013,8 +2007,6 @@ xfs_init_zones(void) kmem_zone_destroy(xfs_bmap_free_item_zone); out_destroy_log_ticket_zone: kmem_zone_destroy(xfs_log_ticket_zone); - out_free_ioend_bioset: - bioset_exit(&xfs_ioend_bioset); out: return -ENOMEM; } @@ -2045,7 +2037,6 @@ xfs_destroy_zones(void) kmem_zone_destroy(xfs_btree_cur_zone); kmem_zone_destroy(xfs_bmap_free_item_zone); kmem_zone_destroy(xfs_log_ticket_zone); - bioset_exit(&xfs_ioend_bioset); } STATIC int __init diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 2103b94cb1bf..e87f44810c53 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -4,6 +4,7 @@ #include <linux/atomic.h> #include <linux/bitmap.h> +#include <linux/blk_types.h> #include <linux/mm.h> #include <linux/types.h> #include <linux/mm_types.h> @@ -11,6 +12,7 @@ struct address_space; struct fiemap_extent_info; struct inode; +struct iomap_writepage_ctx; struct iov_iter; struct kiocb; struct page; @@ -165,6 +167,45 @@ loff_t iomap_seek_data(struct inode *inode, loff_t offset, sector_t iomap_bmap(struct address_space *mapping, sector_t bno, const struct iomap_ops *ops); +/* + * Structure for writeback I/O completions. + */ +struct iomap_ioend { + struct list_head io_list; /* next ioend in chain */ + u16 io_type; + u16 io_flags; + struct inode *io_inode; /* file being written to */ + size_t io_size; /* size of the extent */ + loff_t io_offset; /* offset in the file */ + struct bio *io_bio; /* bio being built */ + struct bio io_inline_bio; /* MUST BE LAST! */ +}; + +struct iomap_writeback_ops { + int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode, + loff_t offset); + int (*submit_ioend)(struct iomap_ioend *ioend, int status); + void (*discard_page)(struct page *page); +}; + +struct iomap_writepage_ctx { + struct iomap iomap; + struct iomap_ioend *ioend; + const struct iomap_writeback_ops *ops; +}; + +void iomap_finish_ioend(struct iomap_ioend *ioend, int error); +void iomap_finish_ioends(struct iomap_ioend *ioend, int error); +void iomap_ioend_try_merge(struct iomap_ioend *ioend, + struct list_head *more_ioends); +void iomap_sort_ioends(struct list_head *ioend_list); +int iomap_writepage(struct page *page, struct writeback_control *wbc, + struct iomap_writepage_ctx *wpc, + const struct iomap_writeback_ops *ops); +int iomap_writepages(struct address_space *mapping, + struct writeback_control *wbc, struct iomap_writepage_ctx *wpc, + const struct iomap_writeback_ops *ops); + /* * Flags for direct I/O ->end_io: */
Takes the xfs writeback code and move it to iomap.c. A new structure with three methods is added as the abstraction from the generic writeback code to the file system. These methods are used to map blocks, submit an ioend, and cancel a page that encountered an error before it was added to an ioend. Note that we temporarily lose the writepage tracing, but that will be added back soon. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/iomap.c | 521 ++++++++++++++++++++++++++++++++++++- fs/xfs/xfs_aops.c | 584 ++++-------------------------------------- fs/xfs/xfs_aops.h | 16 -- fs/xfs/xfs_super.c | 11 +- include/linux/iomap.h | 41 +++ 5 files changed, 605 insertions(+), 568 deletions(-)