xfs: allow xfs_swap_range to use older extent swap algorithms

If userspace permits non-atomic swap operations, use the older code
paths to implement the same functionality.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

3 files changed, 42 insertions, 7 deletions

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 71165ae1aa7c..a0ce5e5dd5e4 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1256,7 +1256,7 @@ out_trans_cancel:
  * reject and log the attempt. basically we are putting the responsibility on
  * userspace to get this right.
  */
-static int
+int
 xfs_swap_extents_check_format(
 	struct xfs_inode	*ip,	/* target inode */
 	struct xfs_inode	*tip)	/* tmp inode */
@@ -1393,7 +1393,7 @@ xfs_swap_change_owner(
 }
 
 /* Swap the extents of two files by swapping data forks. */
-STATIC int
+int
 xfs_swap_extent_forks(
 	struct xfs_trans	**tpp,
 	struct xfs_swapext_req	*req)
diff --git a/fs/xfs/xfs_bmap_util.h b/fs/xfs/xfs_bmap_util.h
index 9f993168b55b..de3173e64f47 100644
--- a/fs/xfs/xfs_bmap_util.h
+++ b/fs/xfs/xfs_bmap_util.h
@@ -69,6 +69,10 @@ int	xfs_free_eofblocks(struct xfs_inode *ip);
 int	xfs_swap_extents(struct xfs_inode *ip, struct xfs_inode *tip,
 			 struct xfs_swapext *sx);
 
+struct xfs_swapext_req;
+int xfs_swap_extent_forks(struct xfs_trans **tpp, struct xfs_swapext_req *req);
+int xfs_swap_extents_check_format(struct xfs_inode *ip, struct xfs_inode *tip);
+
 xfs_daddr_t xfs_fsb_to_db(struct xfs_inode *ip, xfs_fsblock_t fsb);
 
 xfs_extnum_t xfs_bmap_count_leaves(struct xfs_ifork *ifp, xfs_filblks_t *count);
diff --git a/fs/xfs/xfs_swaprange.c b/fs/xfs/xfs_swaprange.c
index 68efdda61c5e..901440b812ec 100644
--- a/fs/xfs/xfs_swaprange.c
+++ b/fs/xfs/xfs_swaprange.c
@@ -174,9 +174,6 @@ xfs_swap_range(
 	struct xfs_trans	*tp;
 	int			error;
 
-	if (!xfs_sb_version_hasatomicswap(&mp->m_sb))
-		return -EOPNOTSUPP;
-
 	req.startoff1 = XFS_B_TO_FSBT(mp, fsr->file1_offset);
 	req.startoff2 = XFS_B_TO_FSBT(mp, fsr->file2_offset);
 	req.blockcount = XFS_B_TO_FSB(mp, fsr->length);
@@ -246,11 +243,45 @@ xfs_swap_range(
 	if (error)
 		goto out_trans_cancel;
 
-	/* Perform the file range swap. */
 	if (fsr->flags & FILE_SWAP_RANGE_TO_EOF)
 		req.flags |= XFS_SWAPEXT_SET_SIZES;
 
-	error = xfs_swapext_atomic(&tp, &req);
+	/* Perform the file range swap... */
+	if (xfs_sb_version_hasatomicswap(&mp->m_sb)) {
+		/* ...by using the atomic swap, since it's available. */
+		error = xfs_swapext_atomic(&tp, &req);
+	} else if ((fsr->flags & FILE_SWAP_RANGE_NONATOMIC) &&
+		   (xfs_sb_version_hasreflink(&mp->m_sb) ||
+		    xfs_sb_version_hasrmapbt(&mp->m_sb))) {
+		/*
+		 * ...by using deferred bmap operations, which are only
+		 * supported if userspace is ok with a non-atomic swap
+		 * (e.g. xfs_fsr) and the log supports deferred bmap.
+		 */
+		error = xfs_swapext_deferred_bmap(&tp, &req);
+	} else if ((fsr->flags & FILE_SWAP_RANGE_NONATOMIC) &&
+		   (fsr->flags & FILE_SWAP_RANGE_FULL_FILES) &&
+		   !(fsr->flags & FILE_SWAP_RANGE_TO_EOF) &&
+		   fsr->file1_offset == 0 && fsr->file2_offset == 0 &&
+		   fsr->length == ip1->i_d.di_size &&
+		   fsr->length == ip2->i_d.di_size) {
+		/*
+		 * ...by using the old bmap owner change code, if we're a
+		 * defrag tool doing a full file swap and we're ok with
+		 * non-atomic mode.
+		 */
+		error = xfs_swap_extents_check_format(ip2, ip1);
+		if (error) {
+			xfs_notice(mp,
+		"%s: inode 0x%llx format is incompatible for exchanging.",
+					__func__, ip2->i_ino);
+			goto out_trans_cancel;
+		}
+		error = xfs_swap_extent_forks(&tp, &req);
+	} else {
+		/* ...or not at all, because we cannot do it. */
+		error = -EOPNOTSUPP;
+	}
 	if (error)
 		goto out_trans_cancel;