Unverified Commit 6ef6a0e8 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Christian Brauner
Browse files

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: b53fdb21 ("iomap: improve shared block detection in iomap_unshare_iter")
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/172796813294.1131942.15762084021076932620.stgit@frogsfrogsfrogs


Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent b8c4076d

fs/dax.c

+1 −2
Original line number Diff line number Diff line
@@ -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();

fs/iomap/buffered-io.c

+16 −14
Original line number Diff line number Diff line
@@ -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 {

include/linux/iomap.h

+1 −0
Original line number Diff line number Diff line
@@ -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,