Commit 17fa6a5f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'vfs-6.12-rc6.iomap' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs 

Pull iomap fixes from Christian Brauner:
 "Fixes for iomap to prevent data corruption bugs in the fallocate
  unshare range implementation of fsdax and a small cleanup to turn
  iomap_want_unshare_iter() into an inline function"

* tag 'vfs-6.12-rc6.iomap' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
  iomap: turn iomap_want_unshare_iter into an inline function
  fsdax: dax_unshare_iter needs to copy entire blocks
  fsdax: remove zeroing code from dax_unshare_iter
  iomap: share iomap_unshare_iter predicate code with fsdax
  xfs: don't allocate COW extents when unsharing a hole
parents d56239a8 6db38858

fs/dax.c

+28 −17
Original line number Diff line number Diff line
@@ -1262,35 +1262,46 @@ static s64 dax_unshare_iter(struct iomap_iter *iter) 
{

	struct iomap *iomap = &iter->iomap;

	const struct iomap *srcmap = iomap_iter_srcmap(iter);

	loff_t pos = iter->pos;

	loff_t length = iomap_length(iter);

	loff_t copy_pos = iter->pos;

	u64 copy_len = iomap_length(iter);

	u32 mod;

	int id = 0;

	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))

		return length;

	if (!iomap_want_unshare_iter(iter))

		return iomap_length(iter);



	/*

	 * Extend the file range to be aligned to fsblock/pagesize, because

	 * we need to copy entire blocks, not just the byte range specified.

	 * Invalidate the mapping because we're about to CoW.

	 */

	mod = offset_in_page(copy_pos);

	if (mod) {

		copy_len += mod;

		copy_pos -= mod;

	}



	mod = offset_in_page(copy_pos + copy_len);

	if (mod)

		copy_len += PAGE_SIZE - mod;



	invalidate_inode_pages2_range(iter->inode->i_mapping,

				      copy_pos >> PAGE_SHIFT,

				      (copy_pos + copy_len - 1) >> PAGE_SHIFT);



	id = dax_read_lock();

	ret = dax_iomap_direct_access(iomap, pos, length, &daddr, NULL);

	ret = dax_iomap_direct_access(iomap, copy_pos, copy_len, &daddr, NULL);

	if (ret < 0)

		goto out_unlock;



	/* zero the distance if srcmap is HOLE or UNWRITTEN */

	if (srcmap->flags & IOMAP_F_SHARED || srcmap->type == IOMAP_UNWRITTEN) {

		memset(daddr, 0, length);

		dax_flush(iomap->dax_dev, daddr, length);

		ret = length;

		goto out_unlock;

	}



	ret = dax_iomap_direct_access(srcmap, pos, length, &saddr, NULL);

	ret = dax_iomap_direct_access(srcmap, copy_pos, copy_len, &saddr, NULL);

	if (ret < 0)

		goto out_unlock;



	if (copy_mc_to_kernel(daddr, saddr, length) == 0)

		ret = length;

	if (copy_mc_to_kernel(daddr, saddr, copy_len) == 0)

		ret = iomap_length(iter);

	else

		ret = -EIO;

fs/iomap/buffered-io.c

+1 −16
Original line number Diff line number Diff line
@@ -1277,22 +1277,7 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter) 
	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.

	 *

	 * Note that we use srcmap directly instead of iomap_iter_srcmap as

	 * unsharing requires providing a separate source map, and the presence

	 * of one is a good indicator that unsharing is needed, unlike

	 * 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)

	if (!iomap_want_unshare_iter(iter))

		return length;



	do {

fs/xfs/xfs_iomap.c

+1 −1
Original line number Diff line number Diff line
@@ -707,7 +707,7 @@ imap_needs_cow( 
		return false;



	/* when zeroing we don't have to COW holes or unwritten extents */

	if (flags & IOMAP_ZERO) {

	if (flags & (IOMAP_UNSHARE | IOMAP_ZERO)) {

		if (!nimaps ||

		    imap->br_startblock == HOLESTARTBLOCK ||

		    imap->br_state == XFS_EXT_UNWRITTEN)

include/linux/iomap.h

+19 −0
Original line number Diff line number Diff line
@@ -270,6 +270,25 @@ static inline loff_t iomap_last_written_block(struct inode *inode, loff_t pos, 
	return round_up(pos + written, i_blocksize(inode));

}



/*

 * Check if the range needs to be unshared for a FALLOC_FL_UNSHARE_RANGE

 * operation.

 *

 * 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 of one is a good

 * indicator that unsharing is needed, unlike IOMAP_F_SHARED which can be set

 * for any data that goes into the COW fork for XFS.

 */

static inline bool iomap_want_unshare_iter(const struct iomap_iter *iter)

{

	return (iter->iomap.flags & IOMAP_F_SHARED) &&

		iter->srcmap.type == IOMAP_MAPPED;

}



ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,

		const struct iomap_ops *ops, void *private);

int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops);