6.1-stable review patch. If anyone has any objections, please let me know.
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From: Darrick J. Wong djwong@kernel.org
[ Upstream commit 6ef6a0e821d3dad6bf8a5d5508762dba9042c84b ]
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 djwong@kernel.org Link: https://lore.kernel.org/r/172796813294.1131942.15762084021076932620.stgit@fr... Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Christian Brauner brauner@kernel.org Stable-dep-of: 50793801fc7f ("fsdax: dax_unshare_iter needs to copy entire blocks") Signed-off-by: Sasha Levin sashal@kernel.org --- 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 72a437892b4a4..74f9a14565f59 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1231,8 +1231,7 @@ 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 b1af9001e6db0..876273db711d1 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1084,19 +1084,12 @@ int 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 @@ -1104,9 +1097,18 @@ 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 0983dfc9a203c..0a37b54e24926 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -264,6 +264,7 @@ bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags); void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len); 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,