From 6ef6a0e821d3dad6bf8a5d5508762dba9042c84b Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 3 Oct 2024 08:09:16 -0700 Subject: [PATCH] iomap: share iomap_unshare_iter predicate code with fsdax The predicate code that iomap_unshare_iter uses to decide if it's really needs to unshare a file range mapping should be shared with the fsdax version, because right now they're opencoded and inconsistent. Note that we simplify the predicate logic a bit -- we no longer allow unsharing of inline data mappings, but there aren't any filesystems that allow shared inline data currently. This is a fix in the sense that it should have been ported to fsdax. Fixes: b53fdb215d13 ("iomap: improve shared block detection in iomap_unshare_iter") Signed-off-by: Darrick J. Wong Link: https://lore.kernel.org/r/172796813294.1131942.15762084021076932620.stgit@frogsfrogsfrogs Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- fs/dax.c | 3 +-- fs/iomap/buffered-io.c | 30 ++++++++++++++++-------------- include/linux/iomap.h | 1 + 3 files changed, 18 insertions(+), 16 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index c62acd2812f8..5064eefb1c1e 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1268,8 +1268,7 @@ static s64 dax_unshare_iter(struct iomap_iter *iter) s64 ret = 0; void *daddr = NULL, *saddr = NULL; - /* don't bother with blocks that are not shared to start with */ - if (!(iomap->flags & IOMAP_F_SHARED)) + if (!iomap_want_unshare_iter(iter)) return length; id = dax_read_lock(); diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 78ebd265f425..3899169b2cf7 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1309,19 +1309,12 @@ void iomap_file_buffered_write_punch_delalloc(struct inode *inode, } EXPORT_SYMBOL_GPL(iomap_file_buffered_write_punch_delalloc); -static loff_t iomap_unshare_iter(struct iomap_iter *iter) +bool iomap_want_unshare_iter(const struct iomap_iter *iter) { - struct iomap *iomap = &iter->iomap; - loff_t pos = iter->pos; - loff_t length = iomap_length(iter); - loff_t written = 0; - - /* Don't bother with blocks that are not shared to start with. */ - if (!(iomap->flags & IOMAP_F_SHARED)) - return length; - /* - * Don't bother with delalloc reservations, holes or unwritten extents. + * Don't bother with blocks that are not shared to start with; or + * mappings that cannot be shared, such as inline data, delalloc + * reservations, holes or unwritten extents. * * Note that we use srcmap directly instead of iomap_iter_srcmap as * unsharing requires providing a separate source map, and the presence @@ -1329,9 +1322,18 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter) * IOMAP_F_SHARED which can be set for any data that goes into the COW * fork for XFS. */ - if (iter->srcmap.type == IOMAP_HOLE || - iter->srcmap.type == IOMAP_DELALLOC || - iter->srcmap.type == IOMAP_UNWRITTEN) + return (iter->iomap.flags & IOMAP_F_SHARED) && + iter->srcmap.type == IOMAP_MAPPED; +} + +static loff_t iomap_unshare_iter(struct iomap_iter *iter) +{ + struct iomap *iomap = &iter->iomap; + loff_t pos = iter->pos; + loff_t length = iomap_length(iter); + loff_t written = 0; + + if (!iomap_want_unshare_iter(iter)) return length; do { diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 4ad12a3c8bae..d8a7fc84348c 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -267,6 +267,7 @@ void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len); bool iomap_dirty_folio(struct address_space *mapping, struct folio *folio); int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len, const struct iomap_ops *ops); +bool iomap_want_unshare_iter(const struct iomap_iter *iter); int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, const struct iomap_ops *ops); int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,