@@ -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/buffer_head.h>
#include <linux/dax.h>
#include <linux/writeback.h>
+#include <linux/list_sort.h>
#include <linux/swap.h>
#include <linux/bio.h>
#include <linux/sched/signal.h>
@@ -20,6 +21,8 @@
#include "../internal.h"
+static struct bio_set iomap_ioend_bioset;
+
static struct iomap_page *
iomap_page_create(struct inode *inode, struct page *page)
{
@@ -460,6 +463,8 @@ EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate);
int
iomap_releasepage(struct page *page, gfp_t gfp_mask)
{
+ trace_iomap_releasepage(page->mapping->host, page, 0, 0);
+
/*
* mm accommodates an old ext3 case where clean pages might not have had
* the dirty bit cleared. Thus, it can send actual dirty pages to
@@ -475,6 +480,8 @@ EXPORT_SYMBOL_GPL(iomap_releasepage);
void
iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
{
+ trace_iomap_invalidatepage(page->mapping->host, page, offset, len);
+
/*
* If we are invalidating the entire page, clear the dirty state from it
* and release it to avoid unnecessary buildup of the LRU.
@@ -1076,3 +1083,547 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops)
return block_page_mkwrite_return(ret);
}
EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
+
+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.
+ */
+static 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);
+ }
+}
+
+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 (!list_empty(&tmp)) {
+ ioend = list_first_entry(&tmp, struct iomap_ioend, io_list);
+ list_del_init(&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,
+ void (*merge_private)(struct iomap_ioend *ioend,
+ struct iomap_ioend *next))
+{
+ 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;
+ if (next->io_private && merge_private)
+ merge_private(ioend, next);
+ }
+}
+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);
+
+static void iomap_writepage_end_bio(struct bio *bio)
+{
+ struct iomap_ioend *ioend = bio->bi_private;
+
+ iomap_finish_ioend(ioend, blk_status_to_errno(bio->bi_status));
+}
+
+/*
+ * 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)
+{
+ ioend->io_bio->bi_private = ioend;
+ ioend->io_bio->bi_end_io = iomap_writepage_end_bio;
+
+ if (wpc->ops->submit_ioend)
+ error = wpc->ops->submit_ioend(ioend, error);
+ if (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_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;
+ wbc_init_bio(wbc, bio);
+
+ 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_private = NULL;
+ 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);/* also copies over blkcg information */
+ 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)
+{
+ sector_t sector = iomap_sector(&wpc->iomap, offset);
+ unsigned len = i_blocksize(inode);
+ unsigned poff = offset & (PAGE_SIZE - 1);
+ bool merged, same_page = false;
+
+ 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);
+ }
+
+ merged = __bio_try_merge_page(wpc->ioend->io_bio, page, len, poff,
+ &same_page);
+
+ if (iop && !same_page)
+ atomic_inc(&iop->write_count);
+ if (!merged) {
+ if (bio_full(wpc->ioend->io_bio, len)) {
+ 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;
+ wbc_account_cgroup_owner(wbc, page, 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) {
+ if (wpc->ops->discard_page)
+ 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;
+
+ trace_iomap_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 = (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);
@@ -41,6 +41,45 @@ DEFINE_EVENT(iomap_readpage_class, name, \
DEFINE_READPAGE_EVENT(iomap_readpage);
DEFINE_READPAGE_EVENT(iomap_readpages);
+DECLARE_EVENT_CLASS(iomap_page_class,
+ TP_PROTO(struct inode *inode, struct page *page, unsigned long off,
+ unsigned int len),
+ TP_ARGS(inode, page, off, len),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(u64, ino)
+ __field(pgoff_t, pgoff)
+ __field(loff_t, size)
+ __field(unsigned long, offset)
+ __field(unsigned int, length)
+ ),
+ TP_fast_assign(
+ __entry->dev = inode->i_sb->s_dev;
+ __entry->ino = inode->i_ino;
+ __entry->pgoff = page_offset(page);
+ __entry->size = i_size_read(inode);
+ __entry->offset = off;
+ __entry->length = len;
+ ),
+ TP_printk("dev %d:%d ino 0x%llx pgoff 0x%lx size 0x%llx offset %lx "
+ "length %x",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->ino,
+ __entry->pgoff,
+ __entry->size,
+ __entry->offset,
+ __entry->length)
+)
+
+#define DEFINE_PAGE_EVENT(name) \
+DEFINE_EVENT(iomap_page_class, name, \
+ TP_PROTO(struct inode *inode, struct page *page, unsigned long off, \
+ unsigned int len), \
+ TP_ARGS(inode, page, off, len))
+DEFINE_PAGE_EVENT(iomap_writepage);
+DEFINE_PAGE_EVENT(iomap_releasepage);
+DEFINE_PAGE_EVENT(iomap_invalidatepage);
+
#endif /* _IOMAP_TRACE_H */
#undef TRACE_INCLUDE_PATH
@@ -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>
@@ -12,6 +13,7 @@
struct address_space;
struct fiemap_extent_info;
struct inode;
+struct iomap_writepage_ctx;
struct iov_iter;
struct kiocb;
struct page;
@@ -183,6 +185,63 @@ 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; /* IOMAP_F_* */
+ struct inode *io_inode; /* file being written to */
+ size_t io_size; /* size of the extent */
+ loff_t io_offset; /* offset in the file */
+ void *io_private; /* file system private data */
+ struct bio *io_bio; /* bio being built */
+ struct bio io_inline_bio; /* MUST BE LAST! */
+};
+
+struct iomap_writeback_ops {
+ /*
+ * Required, maps the blocks so that writeback can be performed on
+ * the range starting at offset.
+ */
+ int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode,
+ loff_t offset);
+
+ /*
+ * Optional, allows the file systems to perform actions just before
+ * submitting the bio and/or override the bio end_io handler for complex
+ * operations like copy on write extent manipulation or unwritten extent
+ * conversions.
+ */
+ int (*submit_ioend)(struct iomap_ioend *ioend, int status);
+
+ /*
+ * Optional, allows the file system to discard state on a page where
+ * we failed to submit any I/O.
+ */
+ 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_ioends(struct iomap_ioend *ioend, int error);
+void iomap_ioend_try_merge(struct iomap_ioend *ioend,
+ struct list_head *more_ioends,
+ void (*merge_private)(struct iomap_ioend *ioend,
+ struct iomap_ioend *next));
+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:
*/