1 files changed, 43 insertions, 1 deletions
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 3cb41b5d5a26..8ebd9c64aa48 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3116,6 +3116,35 @@ xfs_rename(
 	/*
 	 * Check for expected errors before we dirty the transaction
 	 * so we can return an error without a transaction abort.
+	 *
+	 * Extent count overflow check:
+	 *
+	 * From the perspective of src_dp, a rename operation is essentially a
+	 * directory entry remove operation. Hence the only place where we check
+	 * for extent count overflow for src_dp is in
+	 * xfs_bmap_del_extent_real(). xfs_bmap_del_extent_real() returns
+	 * -ENOSPC when it detects a possible extent count overflow and in
+	 * response, the higher layers of directory handling code do the
+	 * following:
+	 * 1. Data/Free blocks: XFS lets these blocks linger until a
+	 *    future remove operation removes them.
+	 * 2. Dabtree blocks: XFS swaps the blocks with the last block in the
+	 *    Leaf space and unmaps the last block.
+	 *
+	 * For target_dp, there are two cases depending on whether the
+	 * destination directory entry exists or not.
+	 *
+	 * When destination directory entry does not exist (i.e. target_ip ==
+	 * NULL), extent count overflow check is performed only when transaction
+	 * has a non-zero sized space reservation associated with it.  With a
+	 * zero-sized space reservation, XFS allows a rename operation to
+	 * continue only when the directory has sufficient free space in its
+	 * data/leaf/free space blocks to hold the new entry.
+	 *
+	 * When destination directory entry exists (i.e. target_ip != NULL), all
+	 * we need to do is change the inode number associated with the already
+	 * existing entry. Hence there is no need to perform an extent count
+	 * overflow check.
 	 */
 	if (target_ip == NULL) {
 		/*
@@ -3126,6 +3155,12 @@ xfs_rename(
 			error = xfs_dir_canenter(tp, target_dp, target_name);
 			if (error)
 				goto out_trans_cancel;
+		} else {
+			error = xfs_iext_count_may_overflow(target_dp,
+					XFS_DATA_FORK,
+					XFS_IEXT_DIR_MANIP_CNT(mp));
+			if (error)
+				goto out_trans_cancel;
 		}
 	} else {
 		/*
@@ -3291,9 +3326,16 @@ xfs_rename(
 	if (wip) {
 		error = xfs_dir_replace(tp, src_dp, src_name, wip->i_ino,
 					spaceres);
-	} else
+	} else {
+		/*
+		 * NOTE: We don't need to check for extent count overflow here
+		 * because the dir remove name code will leave the dir block in
+		 * place if the extent count would overflow.
+		 */
 		error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
 					   spaceres);
+	}
+
 	if (error)
 		goto out_trans_cancel;