From c039b99792726346ad46ff17c5a5bcb77a5edac4 Mon Sep 17 00:00:00 2001 From: Goldwyn Rodrigues Date: Fri, 18 Oct 2019 16:44:10 -0700 Subject: iomap: use a srcmap for a read-modify-write I/O The srcmap is used to identify where the read is to be performed from. It is passed to ->iomap_begin, which can fill it in if we need to read data for partially written blocks from a different location than the write target. The srcmap is only supported for buffered writes so far. Signed-off-by: Goldwyn Rodrigues [hch: merged two patches, removed the IOMAP_F_COW flag, use iomap as srcmap if not set, adjust length down to srcmap end as well] Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Acked-by: Goldwyn Rodrigues --- fs/iomap/buffered-io.c | 65 +++++++++++++++++++++++++++----------------------- 1 file changed, 35 insertions(+), 30 deletions(-) (limited to 'fs/iomap/buffered-io.c') diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index b61076823544..c62e807956b6 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -234,7 +234,7 @@ static inline bool iomap_block_needs_zeroing(struct inode *inode, static loff_t iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data, - struct iomap *iomap) + struct iomap *iomap, struct iomap *srcmap) { struct iomap_readpage_ctx *ctx = data; struct page *page = ctx->cur_page; @@ -382,7 +382,7 @@ iomap_next_page(struct inode *inode, struct list_head *pages, loff_t pos, static loff_t iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length, - void *data, struct iomap *iomap) + void *data, struct iomap *iomap, struct iomap *srcmap) { struct iomap_readpage_ctx *ctx = data; loff_t done, ret; @@ -402,7 +402,7 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length, ctx->cur_page_in_bio = false; } ret = iomap_readpage_actor(inode, pos + done, length - done, - ctx, iomap); + ctx, iomap, srcmap); } return done; @@ -582,7 +582,7 @@ iomap_read_page_sync(loff_t block_start, struct page *page, unsigned poff, static int __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags, - struct page *page, struct iomap *iomap) + struct page *page, struct iomap *srcmap) { struct iomap_page *iop = iomap_page_create(inode, page); loff_t block_size = i_blocksize(inode); @@ -605,7 +605,7 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags, (to <= poff || to >= poff + plen)) continue; - if (iomap_block_needs_zeroing(inode, iomap, block_start)) { + if (iomap_block_needs_zeroing(inode, srcmap, block_start)) { if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE)) return -EIO; zero_user_segments(page, poff, from, to, poff + plen); @@ -614,7 +614,7 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags, } status = iomap_read_page_sync(block_start, page, poff, plen, - iomap); + srcmap); if (status) return status; } while ((block_start += plen) < block_end); @@ -624,13 +624,15 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags, static int iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, - struct page **pagep, struct iomap *iomap) + struct page **pagep, struct iomap *iomap, struct iomap *srcmap) { const struct iomap_page_ops *page_ops = iomap->page_ops; struct page *page; int status = 0; BUG_ON(pos + len > iomap->offset + iomap->length); + if (srcmap != iomap) + BUG_ON(pos + len > srcmap->offset + srcmap->length); if (fatal_signal_pending(current)) return -EINTR; @@ -648,13 +650,13 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, goto out_no_page; } - if (iomap->type == IOMAP_INLINE) - iomap_read_inline_data(inode, page, iomap); + if (srcmap->type == IOMAP_INLINE) + iomap_read_inline_data(inode, page, srcmap); else if (iomap->flags & IOMAP_F_BUFFER_HEAD) - status = __block_write_begin_int(page, pos, len, NULL, iomap); + status = __block_write_begin_int(page, pos, len, NULL, srcmap); else status = __iomap_write_begin(inode, pos, len, flags, page, - iomap); + srcmap); if (unlikely(status)) goto out_unlock; @@ -740,16 +742,16 @@ iomap_write_end_inline(struct inode *inode, struct page *page, } static int -iomap_write_end(struct inode *inode, loff_t pos, unsigned len, - unsigned copied, struct page *page, struct iomap *iomap) +iomap_write_end(struct inode *inode, loff_t pos, unsigned len, unsigned copied, + struct page *page, struct iomap *iomap, struct iomap *srcmap) { const struct iomap_page_ops *page_ops = iomap->page_ops; loff_t old_size = inode->i_size; int ret; - if (iomap->type == IOMAP_INLINE) { + if (srcmap->type == IOMAP_INLINE) { ret = iomap_write_end_inline(inode, page, iomap, pos, copied); - } else if (iomap->flags & IOMAP_F_BUFFER_HEAD) { + } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) { ret = block_write_end(NULL, inode->i_mapping, pos, len, copied, page, NULL); } else { @@ -780,7 +782,7 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len, static loff_t iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, - struct iomap *iomap) + struct iomap *iomap, struct iomap *srcmap) { struct iov_iter *i = data; long status = 0; @@ -814,7 +816,8 @@ again: break; } - status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap); + status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, + srcmap); if (unlikely(status)) break; @@ -825,8 +828,8 @@ again: flush_dcache_page(page); - status = iomap_write_end(inode, pos, bytes, copied, page, - iomap); + status = iomap_write_end(inode, pos, bytes, copied, page, iomap, + srcmap); if (unlikely(status < 0)) break; copied = status; @@ -879,7 +882,7 @@ EXPORT_SYMBOL_GPL(iomap_file_buffered_write); static loff_t iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data, - struct iomap *iomap) + struct iomap *iomap, struct iomap *srcmap) { long status = 0; ssize_t written = 0; @@ -888,7 +891,7 @@ iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data, if (!(iomap->flags & IOMAP_F_SHARED)) return length; /* don't bother with holes or unwritten extents */ - if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) + if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) return length; do { @@ -897,11 +900,12 @@ iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct page *page; status = iomap_write_begin(inode, pos, bytes, - IOMAP_WRITE_F_UNSHARE, &page, iomap); + IOMAP_WRITE_F_UNSHARE, &page, iomap, srcmap); if (unlikely(status)) return status; - status = iomap_write_end(inode, pos, bytes, bytes, page, iomap); + status = iomap_write_end(inode, pos, bytes, bytes, page, iomap, + srcmap); if (unlikely(status <= 0)) { if (WARN_ON_ONCE(status == 0)) return -EIO; @@ -940,19 +944,19 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len, EXPORT_SYMBOL_GPL(iomap_file_unshare); static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset, - unsigned bytes, struct iomap *iomap) + unsigned bytes, struct iomap *iomap, struct iomap *srcmap) { struct page *page; int status; - status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap); + status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap, srcmap); if (status) return status; zero_user(page, offset, bytes); mark_page_accessed(page); - return iomap_write_end(inode, pos, bytes, bytes, page, iomap); + return iomap_write_end(inode, pos, bytes, bytes, page, iomap, srcmap); } static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes, @@ -964,14 +968,14 @@ static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes, static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count, - void *data, struct iomap *iomap) + void *data, struct iomap *iomap, struct iomap *srcmap) { bool *did_zero = data; loff_t written = 0; int status; /* already zeroed? we're done. */ - if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) + if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) return count; do { @@ -983,7 +987,8 @@ iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count, if (IS_DAX(inode)) status = iomap_dax_zero(pos, offset, bytes, iomap); else - status = iomap_zero(inode, pos, offset, bytes, iomap); + status = iomap_zero(inode, pos, offset, bytes, iomap, + srcmap); if (status < 0) return status; @@ -1033,7 +1038,7 @@ EXPORT_SYMBOL_GPL(iomap_truncate_page); static loff_t iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, - void *data, struct iomap *iomap) + void *data, struct iomap *iomap, struct iomap *srcmap) { struct page *page = data; int ret; -- cgit v1.2.3