| Message ID | 20180702145813.22496-21-hch@lst.de (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Mon, Jul 02, 2018 at 08:58:11AM -0600, Christoph Hellwig wrote: > After already supporting a simple implementation of buffered writes for > the blocksize == PAGE_SIZE case in the last commit this adds full support > even for smaller block sizes. There are three bits of per-block > information in the buffer_head structure that really matter for the iomap > read and write path: > > - uptodate status (BH_uptodate) > - marked as currently under read I/O (BH_Async_Read) > - marked as currently under write I/O (BH_Async_Write) > > Instead of having new per-block structures this now adds a per-page > structure called struct iomap_page to track this information in a slightly > different form: > > - a bitmap for the per-block uptodate status. For worst case of a 64k > page size system this bitmap needs to contain 128 bits. For the > typical 4k page size case it only needs 8 bits, although we still > need a full unsigned long due to the way the atomic bitmap API works. > - two atomic_t counters are used to track the outstanding read and write > counts > > There is quite a bit of boilerplate code as the buffered I/O path uses > various helper methods, but the actual code is very straight forward. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/iomap.c | 279 ++++++++++++++++++++++++++++++++++++++---- > include/linux/iomap.h | 31 +++++ > 2 files changed, 289 insertions(+), 21 deletions(-) > > diff --git a/fs/iomap.c b/fs/iomap.c > index 13cdcf33e6c0..ea1b1ba61ba3 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c ... > @@ -161,13 +295,13 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > return PAGE_SIZE; > } > > - /* we don't support blocksize < PAGE_SIZE quite yet. */ > - WARN_ON_ONCE(pos != page_offset(page)); > - WARN_ON_ONCE(plen != PAGE_SIZE); > + iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen); > + if (plen == 0) > + goto done; > I think the i_size check confused me in the previous go around. It's obviously clear to me now after the iomap zeroing issue and fix, but a one-liner comment couldn't hurt for future reference: /* zero post-eof blocks as the page may be mapped */ That nit aside, this looks good to me and survives my tests: Reviewed-by: Brian Foster <bfoster@redhat.com> > if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) { > zero_user(page, poff, plen); > - SetPageUptodate(page); > + iomap_set_range_uptodate(page, poff, plen); > goto done; > } > > @@ -183,6 +317,14 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > is_contig = true; > } > > + /* > + * If we start a new segment we need to increase the read count, and we > + * need to do so before submitting any previous full bio to make sure > + * that we don't prematurely unlock the page. > + */ > + if (iop) > + atomic_inc(&iop->read_count); > + > if (!ctx->bio || !is_contig || bio_full(ctx->bio)) { > gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL); > int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT; > @@ -203,7 +345,13 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > > __bio_add_page(ctx->bio, page, plen, poff); > done: > - return plen; > + /* > + * Move the caller beyond our range so that it keeps making progress. > + * For that we have to include any leading non-uptodate ranges, but > + * we can skip trailing ones as they will be handled in the next > + * iteration. > + */ > + return pos - orig_pos + plen; > } > > int > @@ -214,8 +362,6 @@ iomap_readpage(struct page *page, const struct iomap_ops *ops) > unsigned poff; > loff_t ret; > > - WARN_ON_ONCE(page_has_buffers(page)); > - > for (poff = 0; poff < PAGE_SIZE; poff += ret) { > ret = iomap_apply(inode, page_offset(page) + poff, > PAGE_SIZE - poff, 0, ops, &ctx, > @@ -341,6 +487,84 @@ iomap_readpages(struct address_space *mapping, struct list_head *pages, > } > EXPORT_SYMBOL_GPL(iomap_readpages); > > +int > +iomap_is_partially_uptodate(struct page *page, unsigned long from, > + unsigned long count) > +{ > + struct iomap_page *iop = to_iomap_page(page); > + struct inode *inode = page->mapping->host; > + unsigned first = from >> inode->i_blkbits; > + unsigned last = (from + count - 1) >> inode->i_blkbits; > + unsigned i; > + > + if (iop) { > + for (i = first; i <= last; i++) > + if (!test_bit(i, iop->uptodate)) > + return 0; > + return 1; > + } > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate); > + > +int > +iomap_releasepage(struct page *page, gfp_t gfp_mask) > +{ > + /* > + * 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 > + * ->releasepage() via shrink_active_list(), skip those here. > + */ > + if (PageDirty(page) || PageWriteback(page)) > + return 0; > + iomap_page_release(page); > + return 1; > +} > +EXPORT_SYMBOL_GPL(iomap_releasepage); > + > +void > +iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len) > +{ > + /* > + * If we are invalidating the entire page, clear the dirty state from it > + * and release it to avoid unnecessary buildup of the LRU. > + */ > + if (offset == 0 && len == PAGE_SIZE) { > + WARN_ON_ONCE(PageWriteback(page)); > + cancel_dirty_page(page); > + iomap_page_release(page); > + } > +} > +EXPORT_SYMBOL_GPL(iomap_invalidatepage); > + > +#ifdef CONFIG_MIGRATION > +int > +iomap_migrate_page(struct address_space *mapping, struct page *newpage, > + struct page *page, enum migrate_mode mode) > +{ > + int ret; > + > + ret = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); > + if (ret != MIGRATEPAGE_SUCCESS) > + return ret; > + > + if (page_has_private(page)) { > + ClearPagePrivate(page); > + set_page_private(newpage, page_private(page)); > + set_page_private(page, 0); > + SetPagePrivate(newpage); > + } > + > + if (mode != MIGRATE_SYNC_NO_COPY) > + migrate_page_copy(newpage, page); > + else > + migrate_page_states(newpage, page); > + return MIGRATEPAGE_SUCCESS; > +} > +EXPORT_SYMBOL_GPL(iomap_migrate_page); > +#endif /* CONFIG_MIGRATION */ > + > static void > iomap_write_failed(struct inode *inode, loff_t pos, unsigned len) > { > @@ -364,6 +588,7 @@ iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page, > > if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) { > zero_user_segments(page, poff, from, to, poff + plen); > + iomap_set_range_uptodate(page, poff, plen); > return 0; > } > > @@ -379,21 +604,33 @@ static int > __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, > struct page *page, struct iomap *iomap) > { > + struct iomap_page *iop = iomap_page_create(inode, page); > loff_t block_size = i_blocksize(inode); > loff_t block_start = pos & ~(block_size - 1); > loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1); > - unsigned poff = block_start & (PAGE_SIZE - 1); > - unsigned plen = min_t(loff_t, PAGE_SIZE - poff, block_end - block_start); > - unsigned from = pos & (PAGE_SIZE - 1), to = from + len; > - > - WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE); > + unsigned from = pos & (PAGE_SIZE - 1), to = from + len, poff, plen; > + int status = 0; > > if (PageUptodate(page)) > return 0; > - if (from <= poff && to >= poff + plen) > - return 0; > - return iomap_read_page_sync(inode, block_start, page, > - poff, plen, from, to, iomap); > + > + do { > + iomap_adjust_read_range(inode, iop, &block_start, > + block_end - block_start, &poff, &plen); > + if (plen == 0) > + break; > + > + if ((from > poff && from < poff + plen) || > + (to > poff && to < poff + plen)) { > + status = iomap_read_page_sync(inode, block_start, page, > + poff, plen, from, to, iomap); > + if (status) > + break; > + } > + > + } while ((block_start += plen) < block_end); > + > + return status; > } > > static int > @@ -476,7 +713,7 @@ __iomap_write_end(struct inode *inode, loff_t pos, unsigned len, > if (unlikely(copied < len && !PageUptodate(page))) { > copied = 0; > } else { > - SetPageUptodate(page); > + iomap_set_range_uptodate(page, pos & (PAGE_SIZE - 1), len); > iomap_set_page_dirty(page); > } > return __generic_write_end(inode, pos, copied, page); > @@ -812,7 +1049,7 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, > block_commit_write(page, 0, length); > } else { > WARN_ON_ONCE(!PageUptodate(page)); > - WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE); > + iomap_page_create(inode, page); > } > > return length; > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > index 5eb9ca8d7ce5..3555d54bf79a 100644 > --- a/include/linux/iomap.h > +++ b/include/linux/iomap.h > @@ -2,6 +2,9 @@ > #ifndef LINUX_IOMAP_H > #define LINUX_IOMAP_H 1 > > +#include <linux/atomic.h> > +#include <linux/bitmap.h> > +#include <linux/mm.h> > #include <linux/types.h> > > struct address_space; > @@ -98,12 +101,40 @@ struct iomap_ops { > ssize_t written, unsigned flags, struct iomap *iomap); > }; > > +/* > + * Structure allocate for each page when block size < PAGE_SIZE to track > + * sub-page uptodate status and I/O completions. > + */ > +struct iomap_page { > + atomic_t read_count; > + atomic_t write_count; > + DECLARE_BITMAP(uptodate, PAGE_SIZE / 512); > +}; > + > +static inline struct iomap_page *to_iomap_page(struct page *page) > +{ > + if (page_has_private(page)) > + return (struct iomap_page *)page_private(page); > + return NULL; > +} > + > ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from, > const struct iomap_ops *ops); > int iomap_readpage(struct page *page, const struct iomap_ops *ops); > int iomap_readpages(struct address_space *mapping, struct list_head *pages, > unsigned nr_pages, const struct iomap_ops *ops); > int iomap_set_page_dirty(struct page *page); > +int iomap_is_partially_uptodate(struct page *page, unsigned long from, > + unsigned long count); > +int iomap_releasepage(struct page *page, gfp_t gfp_mask); > +void iomap_invalidatepage(struct page *page, unsigned int offset, > + unsigned int len); > +#ifdef CONFIG_MIGRATION > +int iomap_migrate_page(struct address_space *mapping, struct page *newpage, > + struct page *page, enum migrate_mode mode); > +#else > +#define iomap_migrate_page NULL > +#endif > int iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len, > const struct iomap_ops *ops); > int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, > -- > 2.18.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 03, 2018 at 08:31:27AM -0400, Brian Foster wrote: > On Mon, Jul 02, 2018 at 08:58:11AM -0600, Christoph Hellwig wrote: > > After already supporting a simple implementation of buffered writes for > > the blocksize == PAGE_SIZE case in the last commit this adds full support > > even for smaller block sizes. There are three bits of per-block > > information in the buffer_head structure that really matter for the iomap > > read and write path: > > > > - uptodate status (BH_uptodate) > > - marked as currently under read I/O (BH_Async_Read) > > - marked as currently under write I/O (BH_Async_Write) > > > > Instead of having new per-block structures this now adds a per-page > > structure called struct iomap_page to track this information in a slightly > > different form: > > > > - a bitmap for the per-block uptodate status. For worst case of a 64k > > page size system this bitmap needs to contain 128 bits. For the > > typical 4k page size case it only needs 8 bits, although we still > > need a full unsigned long due to the way the atomic bitmap API works. > > - two atomic_t counters are used to track the outstanding read and write > > counts > > > > There is quite a bit of boilerplate code as the buffered I/O path uses > > various helper methods, but the actual code is very straight forward. > > > > Signed-off-by: Christoph Hellwig <hch@lst.de> > > --- > > fs/iomap.c | 279 ++++++++++++++++++++++++++++++++++++++---- > > include/linux/iomap.h | 31 +++++ > > 2 files changed, 289 insertions(+), 21 deletions(-) > > > > diff --git a/fs/iomap.c b/fs/iomap.c > > index 13cdcf33e6c0..ea1b1ba61ba3 100644 > > --- a/fs/iomap.c > > +++ b/fs/iomap.c > ... > > @@ -161,13 +295,13 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > > return PAGE_SIZE; > > } > > > > - /* we don't support blocksize < PAGE_SIZE quite yet. */ > > - WARN_ON_ONCE(pos != page_offset(page)); > > - WARN_ON_ONCE(plen != PAGE_SIZE); > > + iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen); > > + if (plen == 0) > > + goto done; > > > > I think the i_size check confused me in the previous go around. It's > obviously clear to me now after the iomap zeroing issue and fix, but a > one-liner comment couldn't hurt for future reference: > > /* zero post-eof blocks as the page may be mapped */ > > That nit aside, this looks good to me and survives my tests: > > Reviewed-by: Brian Foster <bfoster@redhat.com> Looks ok, will insert the comment on its way in. Will test (again)... Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > > > if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) { > > zero_user(page, poff, plen); > > - SetPageUptodate(page); > > + iomap_set_range_uptodate(page, poff, plen); > > goto done; > > } > > > > @@ -183,6 +317,14 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > > is_contig = true; > > } > > > > + /* > > + * If we start a new segment we need to increase the read count, and we > > + * need to do so before submitting any previous full bio to make sure > > + * that we don't prematurely unlock the page. > > + */ > > + if (iop) > > + atomic_inc(&iop->read_count); > > + > > if (!ctx->bio || !is_contig || bio_full(ctx->bio)) { > > gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL); > > int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT; > > @@ -203,7 +345,13 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, > > > > __bio_add_page(ctx->bio, page, plen, poff); > > done: > > - return plen; > > + /* > > + * Move the caller beyond our range so that it keeps making progress. > > + * For that we have to include any leading non-uptodate ranges, but > > + * we can skip trailing ones as they will be handled in the next > > + * iteration. > > + */ > > + return pos - orig_pos + plen; > > } > > > > int > > @@ -214,8 +362,6 @@ iomap_readpage(struct page *page, const struct iomap_ops *ops) > > unsigned poff; > > loff_t ret; > > > > - WARN_ON_ONCE(page_has_buffers(page)); > > - > > for (poff = 0; poff < PAGE_SIZE; poff += ret) { > > ret = iomap_apply(inode, page_offset(page) + poff, > > PAGE_SIZE - poff, 0, ops, &ctx, > > @@ -341,6 +487,84 @@ iomap_readpages(struct address_space *mapping, struct list_head *pages, > > } > > EXPORT_SYMBOL_GPL(iomap_readpages); > > > > +int > > +iomap_is_partially_uptodate(struct page *page, unsigned long from, > > + unsigned long count) > > +{ > > + struct iomap_page *iop = to_iomap_page(page); > > + struct inode *inode = page->mapping->host; > > + unsigned first = from >> inode->i_blkbits; > > + unsigned last = (from + count - 1) >> inode->i_blkbits; > > + unsigned i; > > + > > + if (iop) { > > + for (i = first; i <= last; i++) > > + if (!test_bit(i, iop->uptodate)) > > + return 0; > > + return 1; > > + } > > + > > + return 0; > > +} > > +EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate); > > + > > +int > > +iomap_releasepage(struct page *page, gfp_t gfp_mask) > > +{ > > + /* > > + * 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 > > + * ->releasepage() via shrink_active_list(), skip those here. > > + */ > > + if (PageDirty(page) || PageWriteback(page)) > > + return 0; > > + iomap_page_release(page); > > + return 1; > > +} > > +EXPORT_SYMBOL_GPL(iomap_releasepage); > > + > > +void > > +iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len) > > +{ > > + /* > > + * If we are invalidating the entire page, clear the dirty state from it > > + * and release it to avoid unnecessary buildup of the LRU. > > + */ > > + if (offset == 0 && len == PAGE_SIZE) { > > + WARN_ON_ONCE(PageWriteback(page)); > > + cancel_dirty_page(page); > > + iomap_page_release(page); > > + } > > +} > > +EXPORT_SYMBOL_GPL(iomap_invalidatepage); > > + > > +#ifdef CONFIG_MIGRATION > > +int > > +iomap_migrate_page(struct address_space *mapping, struct page *newpage, > > + struct page *page, enum migrate_mode mode) > > +{ > > + int ret; > > + > > + ret = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); > > + if (ret != MIGRATEPAGE_SUCCESS) > > + return ret; > > + > > + if (page_has_private(page)) { > > + ClearPagePrivate(page); > > + set_page_private(newpage, page_private(page)); > > + set_page_private(page, 0); > > + SetPagePrivate(newpage); > > + } > > + > > + if (mode != MIGRATE_SYNC_NO_COPY) > > + migrate_page_copy(newpage, page); > > + else > > + migrate_page_states(newpage, page); > > + return MIGRATEPAGE_SUCCESS; > > +} > > +EXPORT_SYMBOL_GPL(iomap_migrate_page); > > +#endif /* CONFIG_MIGRATION */ > > + > > static void > > iomap_write_failed(struct inode *inode, loff_t pos, unsigned len) > > { > > @@ -364,6 +588,7 @@ iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page, > > > > if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) { > > zero_user_segments(page, poff, from, to, poff + plen); > > + iomap_set_range_uptodate(page, poff, plen); > > return 0; > > } > > > > @@ -379,21 +604,33 @@ static int > > __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, > > struct page *page, struct iomap *iomap) > > { > > + struct iomap_page *iop = iomap_page_create(inode, page); > > loff_t block_size = i_blocksize(inode); > > loff_t block_start = pos & ~(block_size - 1); > > loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1); > > - unsigned poff = block_start & (PAGE_SIZE - 1); > > - unsigned plen = min_t(loff_t, PAGE_SIZE - poff, block_end - block_start); > > - unsigned from = pos & (PAGE_SIZE - 1), to = from + len; > > - > > - WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE); > > + unsigned from = pos & (PAGE_SIZE - 1), to = from + len, poff, plen; > > + int status = 0; > > > > if (PageUptodate(page)) > > return 0; > > - if (from <= poff && to >= poff + plen) > > - return 0; > > - return iomap_read_page_sync(inode, block_start, page, > > - poff, plen, from, to, iomap); > > + > > + do { > > + iomap_adjust_read_range(inode, iop, &block_start, > > + block_end - block_start, &poff, &plen); > > + if (plen == 0) > > + break; > > + > > + if ((from > poff && from < poff + plen) || > > + (to > poff && to < poff + plen)) { > > + status = iomap_read_page_sync(inode, block_start, page, > > + poff, plen, from, to, iomap); > > + if (status) > > + break; > > + } > > + > > + } while ((block_start += plen) < block_end); > > + > > + return status; > > } > > > > static int > > @@ -476,7 +713,7 @@ __iomap_write_end(struct inode *inode, loff_t pos, unsigned len, > > if (unlikely(copied < len && !PageUptodate(page))) { > > copied = 0; > > } else { > > - SetPageUptodate(page); > > + iomap_set_range_uptodate(page, pos & (PAGE_SIZE - 1), len); > > iomap_set_page_dirty(page); > > } > > return __generic_write_end(inode, pos, copied, page); > > @@ -812,7 +1049,7 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, > > block_commit_write(page, 0, length); > > } else { > > WARN_ON_ONCE(!PageUptodate(page)); > > - WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE); > > + iomap_page_create(inode, page); > > } > > > > return length; > > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > > index 5eb9ca8d7ce5..3555d54bf79a 100644 > > --- a/include/linux/iomap.h > > +++ b/include/linux/iomap.h > > @@ -2,6 +2,9 @@ > > #ifndef LINUX_IOMAP_H > > #define LINUX_IOMAP_H 1 > > > > +#include <linux/atomic.h> > > +#include <linux/bitmap.h> > > +#include <linux/mm.h> > > #include <linux/types.h> > > > > struct address_space; > > @@ -98,12 +101,40 @@ struct iomap_ops { > > ssize_t written, unsigned flags, struct iomap *iomap); > > }; > > > > +/* > > + * Structure allocate for each page when block size < PAGE_SIZE to track > > + * sub-page uptodate status and I/O completions. > > + */ > > +struct iomap_page { > > + atomic_t read_count; > > + atomic_t write_count; > > + DECLARE_BITMAP(uptodate, PAGE_SIZE / 512); > > +}; > > + > > +static inline struct iomap_page *to_iomap_page(struct page *page) > > +{ > > + if (page_has_private(page)) > > + return (struct iomap_page *)page_private(page); > > + return NULL; > > +} > > + > > ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from, > > const struct iomap_ops *ops); > > int iomap_readpage(struct page *page, const struct iomap_ops *ops); > > int iomap_readpages(struct address_space *mapping, struct list_head *pages, > > unsigned nr_pages, const struct iomap_ops *ops); > > int iomap_set_page_dirty(struct page *page); > > +int iomap_is_partially_uptodate(struct page *page, unsigned long from, > > + unsigned long count); > > +int iomap_releasepage(struct page *page, gfp_t gfp_mask); > > +void iomap_invalidatepage(struct page *page, unsigned int offset, > > + unsigned int len); > > +#ifdef CONFIG_MIGRATION > > +int iomap_migrate_page(struct address_space *mapping, struct page *newpage, > > + struct page *page, enum migrate_mode mode); > > +#else > > +#define iomap_migrate_page NULL > > +#endif > > int iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len, > > const struct iomap_ops *ops); > > int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, > > -- > > 2.18.0 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/iomap.c b/fs/iomap.c index 13cdcf33e6c0..ea1b1ba61ba3 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -17,6 +17,7 @@ #include <linux/iomap.h> #include <linux/uaccess.h> #include <linux/gfp.h> +#include <linux/migrate.h> #include <linux/mm.h> #include <linux/mm_inline.h> #include <linux/swap.h> @@ -104,6 +105,138 @@ iomap_sector(struct iomap *iomap, loff_t pos) return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT; } +static struct iomap_page * +iomap_page_create(struct inode *inode, struct page *page) +{ + struct iomap_page *iop = to_iomap_page(page); + + if (iop || i_blocksize(inode) == PAGE_SIZE) + return iop; + + iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL); + atomic_set(&iop->read_count, 0); + atomic_set(&iop->write_count, 0); + bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE); + set_page_private(page, (unsigned long)iop); + SetPagePrivate(page); + return iop; +} + +static void +iomap_page_release(struct page *page) +{ + struct iomap_page *iop = to_iomap_page(page); + + if (!iop) + return; + WARN_ON_ONCE(atomic_read(&iop->read_count)); + WARN_ON_ONCE(atomic_read(&iop->write_count)); + ClearPagePrivate(page); + set_page_private(page, 0); + kfree(iop); +} + +/* + * Calculate the range inside the page that we actually need to read. + */ +static void +iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop, + loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp) +{ + unsigned block_bits = inode->i_blkbits; + unsigned block_size = (1 << block_bits); + unsigned poff = *pos & (PAGE_SIZE - 1); + unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length); + unsigned first = poff >> block_bits; + unsigned last = (poff + plen - 1) >> block_bits; + unsigned end = (i_size_read(inode) & (PAGE_SIZE - 1)) >> block_bits; + + /* + * If the block size is smaller than the page size we need to check the + * per-block uptodate status and adjust the offset and length if needed + * to avoid reading in already uptodate ranges. + */ + if (iop) { + unsigned int i; + + /* move forward for each leading block marked uptodate */ + for (i = first; i <= last; i++) { + if (!test_bit(i, iop->uptodate)) + break; + *pos += block_size; + poff += block_size; + plen -= block_size; + first++; + } + + /* truncate len if we find any trailing uptodate block(s) */ + for ( ; i <= last; i++) { + if (test_bit(i, iop->uptodate)) { + plen -= (last - i + 1) * block_size; + last = i - 1; + break; + } + } + } + + /* + * If the extent spans the block that contains the i_size we need to + * handle both halves separately so that we properly zero data in the + * page cache for blocks that are entirely outside of i_size. + */ + if (first <= end && last > end) + plen -= (last - end) * block_size; + + *offp = poff; + *lenp = plen; +} + +static void +iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len) +{ + struct iomap_page *iop = to_iomap_page(page); + struct inode *inode = page->mapping->host; + unsigned first = off >> inode->i_blkbits; + unsigned last = (off + len - 1) >> inode->i_blkbits; + unsigned int i; + bool uptodate = true; + + if (iop) { + for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) { + if (i >= first && i <= last) + set_bit(i, iop->uptodate); + else if (!test_bit(i, iop->uptodate)) + uptodate = false; + } + } + + if (uptodate && !PageError(page)) + SetPageUptodate(page); +} + +static void +iomap_read_finish(struct iomap_page *iop, struct page *page) +{ + if (!iop || atomic_dec_and_test(&iop->read_count)) + unlock_page(page); +} + +static void +iomap_read_page_end_io(struct bio_vec *bvec, int error) +{ + struct page *page = bvec->bv_page; + struct iomap_page *iop = to_iomap_page(page); + + if (unlikely(error)) { + ClearPageUptodate(page); + SetPageError(page); + } else { + iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len); + } + + iomap_read_finish(iop, page); +} + static void iomap_read_inline_data(struct inode *inode, struct page *page, struct iomap *iomap) @@ -132,7 +265,7 @@ iomap_read_end_io(struct bio *bio) int i; bio_for_each_segment_all(bvec, bio, i) - page_endio(bvec->bv_page, false, error); + iomap_read_page_end_io(bvec, error); bio_put(bio); } @@ -150,9 +283,10 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, { struct iomap_readpage_ctx *ctx = data; struct page *page = ctx->cur_page; - unsigned poff = pos & (PAGE_SIZE - 1); - unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length); + struct iomap_page *iop = iomap_page_create(inode, page); bool is_contig = false; + loff_t orig_pos = pos; + unsigned poff, plen; sector_t sector; if (iomap->type == IOMAP_INLINE) { @@ -161,13 +295,13 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, return PAGE_SIZE; } - /* we don't support blocksize < PAGE_SIZE quite yet. */ - WARN_ON_ONCE(pos != page_offset(page)); - WARN_ON_ONCE(plen != PAGE_SIZE); + iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen); + if (plen == 0) + goto done; if (iomap->type != IOMAP_MAPPED || pos >= i_size_read(inode)) { zero_user(page, poff, plen); - SetPageUptodate(page); + iomap_set_range_uptodate(page, poff, plen); goto done; } @@ -183,6 +317,14 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, is_contig = true; } + /* + * If we start a new segment we need to increase the read count, and we + * need to do so before submitting any previous full bio to make sure + * that we don't prematurely unlock the page. + */ + if (iop) + atomic_inc(&iop->read_count); + if (!ctx->bio || !is_contig || bio_full(ctx->bio)) { gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL); int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT; @@ -203,7 +345,13 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, __bio_add_page(ctx->bio, page, plen, poff); done: - return plen; + /* + * Move the caller beyond our range so that it keeps making progress. + * For that we have to include any leading non-uptodate ranges, but + * we can skip trailing ones as they will be handled in the next + * iteration. + */ + return pos - orig_pos + plen; } int @@ -214,8 +362,6 @@ iomap_readpage(struct page *page, const struct iomap_ops *ops) unsigned poff; loff_t ret; - WARN_ON_ONCE(page_has_buffers(page)); - for (poff = 0; poff < PAGE_SIZE; poff += ret) { ret = iomap_apply(inode, page_offset(page) + poff, PAGE_SIZE - poff, 0, ops, &ctx, @@ -341,6 +487,84 @@ iomap_readpages(struct address_space *mapping, struct list_head *pages, } EXPORT_SYMBOL_GPL(iomap_readpages); +int +iomap_is_partially_uptodate(struct page *page, unsigned long from, + unsigned long count) +{ + struct iomap_page *iop = to_iomap_page(page); + struct inode *inode = page->mapping->host; + unsigned first = from >> inode->i_blkbits; + unsigned last = (from + count - 1) >> inode->i_blkbits; + unsigned i; + + if (iop) { + for (i = first; i <= last; i++) + if (!test_bit(i, iop->uptodate)) + return 0; + return 1; + } + + return 0; +} +EXPORT_SYMBOL_GPL(iomap_is_partially_uptodate); + +int +iomap_releasepage(struct page *page, gfp_t gfp_mask) +{ + /* + * 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 + * ->releasepage() via shrink_active_list(), skip those here. + */ + if (PageDirty(page) || PageWriteback(page)) + return 0; + iomap_page_release(page); + return 1; +} +EXPORT_SYMBOL_GPL(iomap_releasepage); + +void +iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len) +{ + /* + * If we are invalidating the entire page, clear the dirty state from it + * and release it to avoid unnecessary buildup of the LRU. + */ + if (offset == 0 && len == PAGE_SIZE) { + WARN_ON_ONCE(PageWriteback(page)); + cancel_dirty_page(page); + iomap_page_release(page); + } +} +EXPORT_SYMBOL_GPL(iomap_invalidatepage); + +#ifdef CONFIG_MIGRATION +int +iomap_migrate_page(struct address_space *mapping, struct page *newpage, + struct page *page, enum migrate_mode mode) +{ + int ret; + + ret = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); + if (ret != MIGRATEPAGE_SUCCESS) + return ret; + + if (page_has_private(page)) { + ClearPagePrivate(page); + set_page_private(newpage, page_private(page)); + set_page_private(page, 0); + SetPagePrivate(newpage); + } + + if (mode != MIGRATE_SYNC_NO_COPY) + migrate_page_copy(newpage, page); + else + migrate_page_states(newpage, page); + return MIGRATEPAGE_SUCCESS; +} +EXPORT_SYMBOL_GPL(iomap_migrate_page); +#endif /* CONFIG_MIGRATION */ + static void iomap_write_failed(struct inode *inode, loff_t pos, unsigned len) { @@ -364,6 +588,7 @@ iomap_read_page_sync(struct inode *inode, loff_t block_start, struct page *page, if (iomap->type != IOMAP_MAPPED || block_start >= i_size_read(inode)) { zero_user_segments(page, poff, from, to, poff + plen); + iomap_set_range_uptodate(page, poff, plen); return 0; } @@ -379,21 +604,33 @@ static int __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, struct page *page, struct iomap *iomap) { + struct iomap_page *iop = iomap_page_create(inode, page); loff_t block_size = i_blocksize(inode); loff_t block_start = pos & ~(block_size - 1); loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1); - unsigned poff = block_start & (PAGE_SIZE - 1); - unsigned plen = min_t(loff_t, PAGE_SIZE - poff, block_end - block_start); - unsigned from = pos & (PAGE_SIZE - 1), to = from + len; - - WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE); + unsigned from = pos & (PAGE_SIZE - 1), to = from + len, poff, plen; + int status = 0; if (PageUptodate(page)) return 0; - if (from <= poff && to >= poff + plen) - return 0; - return iomap_read_page_sync(inode, block_start, page, - poff, plen, from, to, iomap); + + do { + iomap_adjust_read_range(inode, iop, &block_start, + block_end - block_start, &poff, &plen); + if (plen == 0) + break; + + if ((from > poff && from < poff + plen) || + (to > poff && to < poff + plen)) { + status = iomap_read_page_sync(inode, block_start, page, + poff, plen, from, to, iomap); + if (status) + break; + } + + } while ((block_start += plen) < block_end); + + return status; } static int @@ -476,7 +713,7 @@ __iomap_write_end(struct inode *inode, loff_t pos, unsigned len, if (unlikely(copied < len && !PageUptodate(page))) { copied = 0; } else { - SetPageUptodate(page); + iomap_set_range_uptodate(page, pos & (PAGE_SIZE - 1), len); iomap_set_page_dirty(page); } return __generic_write_end(inode, pos, copied, page); @@ -812,7 +1049,7 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, block_commit_write(page, 0, length); } else { WARN_ON_ONCE(!PageUptodate(page)); - WARN_ON_ONCE(i_blocksize(inode) < PAGE_SIZE); + iomap_page_create(inode, page); } return length; diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 5eb9ca8d7ce5..3555d54bf79a 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -2,6 +2,9 @@ #ifndef LINUX_IOMAP_H #define LINUX_IOMAP_H 1 +#include <linux/atomic.h> +#include <linux/bitmap.h> +#include <linux/mm.h> #include <linux/types.h> struct address_space; @@ -98,12 +101,40 @@ struct iomap_ops { ssize_t written, unsigned flags, struct iomap *iomap); }; +/* + * Structure allocate for each page when block size < PAGE_SIZE to track + * sub-page uptodate status and I/O completions. + */ +struct iomap_page { + atomic_t read_count; + atomic_t write_count; + DECLARE_BITMAP(uptodate, PAGE_SIZE / 512); +}; + +static inline struct iomap_page *to_iomap_page(struct page *page) +{ + if (page_has_private(page)) + return (struct iomap_page *)page_private(page); + return NULL; +} + ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from, const struct iomap_ops *ops); int iomap_readpage(struct page *page, const struct iomap_ops *ops); int iomap_readpages(struct address_space *mapping, struct list_head *pages, unsigned nr_pages, const struct iomap_ops *ops); int iomap_set_page_dirty(struct page *page); +int iomap_is_partially_uptodate(struct page *page, unsigned long from, + unsigned long count); +int iomap_releasepage(struct page *page, gfp_t gfp_mask); +void iomap_invalidatepage(struct page *page, unsigned int offset, + unsigned int len); +#ifdef CONFIG_MIGRATION +int iomap_migrate_page(struct address_space *mapping, struct page *newpage, + struct page *page, enum migrate_mode mode); +#else +#define iomap_migrate_page NULL +#endif int iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len, const struct iomap_ops *ops); int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
After already supporting a simple implementation of buffered writes for the blocksize == PAGE_SIZE case in the last commit this adds full support even for smaller block sizes. There are three bits of per-block information in the buffer_head structure that really matter for the iomap read and write path: - uptodate status (BH_uptodate) - marked as currently under read I/O (BH_Async_Read) - marked as currently under write I/O (BH_Async_Write) Instead of having new per-block structures this now adds a per-page structure called struct iomap_page to track this information in a slightly different form: - a bitmap for the per-block uptodate status. For worst case of a 64k page size system this bitmap needs to contain 128 bits. For the typical 4k page size case it only needs 8 bits, although we still need a full unsigned long due to the way the atomic bitmap API works. - two atomic_t counters are used to track the outstanding read and write counts There is quite a bit of boilerplate code as the buffered I/O path uses various helper methods, but the actual code is very straight forward. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/iomap.c | 279 ++++++++++++++++++++++++++++++++++++++---- include/linux/iomap.h | 31 +++++ 2 files changed, 289 insertions(+), 21 deletions(-)