Commit 4f29e10d authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: rework breaking of shared extents in xfs_file_iomap_begin 



Rework the data flow in xfs_file_iomap_begin where we decide if we have
to break shared extents.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
parent affe250a

fs/xfs/xfs_iomap.c

+7 −5
Original line number Diff line number Diff line
@@ -982,7 +982,7 @@ xfs_file_iomap_begin( 
	 * been done up front, so we don't need to do them here.

	 */

	if (xfs_is_cow_inode(ip)) {

		struct xfs_bmbt_irec	orig = imap;

		struct xfs_bmbt_irec	cmap;

		bool			directio = (flags & IOMAP_DIRECT);



		/* if zeroing doesn't need COW allocation, then we are done. */
@@ -991,7 +991,8 @@ xfs_file_iomap_begin( 
			goto out_found;



		/* may drop and re-acquire the ilock */

		error = xfs_reflink_allocate_cow(ip, &imap, &shared, &lockmode,

		cmap = imap;

		error = xfs_reflink_allocate_cow(ip, &cmap, &shared, &lockmode,

				directio);

		if (error)

			goto out_unlock;
@@ -1002,10 +1003,11 @@ xfs_file_iomap_begin( 
		 * write code can perform read-modify-write operations; we

		 * won't need the CoW fork mapping until writeback.  For direct

		 * I/O, which must be block aligned, we need to report the

		 * newly allocated address.

		 * newly allocated address.  If the data fork has a hole, copy

		 * the COW fork mapping to avoid allocating to the data fork.

		 */

		if (!directio && orig.br_startblock != HOLESTARTBLOCK)

			imap = orig;

		if (directio || imap.br_startblock == HOLESTARTBLOCK)

			imap = cmap;



		end_fsb = imap.br_startoff + imap.br_blockcount;

		length = XFS_FSB_TO_B(mp, end_fsb) - offset;