xfs: refactor inode unlinked pointer update functions

Hoist the functions that update an inode's unlinked pointer updates into
a helper.  No functional changes.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>

fs/xfs/xfs_inode.c

@@ -1943,6 +1943,85 @@ xfs_iunlink_update_bucket(
 	return 0;
 }
 
+/* Set an on-disk inode's next_unlinked pointer. */
+STATIC void
+xfs_iunlink_update_dinode(
+	struct xfs_trans	*tp,
+	xfs_agnumber_t		agno,
+	xfs_agino_t		agino,
+	struct xfs_buf		*ibp,
+	struct xfs_dinode	*dip,
+	struct xfs_imap		*imap,
+	xfs_agino_t		next_agino)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	int			offset;
+
+	ASSERT(xfs_verify_agino_or_null(mp, agno, next_agino));
+
+	trace_xfs_iunlink_update_dinode(mp, agno, agino,
+			be32_to_cpu(dip->di_next_unlinked), next_agino);
+
+	dip->di_next_unlinked = cpu_to_be32(next_agino);
+	offset = imap->im_boffset +
+			offsetof(struct xfs_dinode, di_next_unlinked);
+
+	/* need to recalc the inode CRC if appropriate */
+	xfs_dinode_calc_crc(mp, dip);
+	xfs_trans_inode_buf(tp, ibp);
+	xfs_trans_log_buf(tp, ibp, offset, offset + sizeof(xfs_agino_t) - 1);
+	xfs_inobp_check(mp, ibp);
+}
+
+/* Set an in-core inode's unlinked pointer and return the old value. */
+STATIC int
+xfs_iunlink_update_inode(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	xfs_agnumber_t		agno,
+	xfs_agino_t		next_agino,
+	xfs_agino_t		*old_next_agino)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xfs_dinode	*dip;
+	struct xfs_buf		*ibp;
+	xfs_agino_t		old_value;
+	int			error;
+
+	ASSERT(xfs_verify_agino_or_null(mp, agno, next_agino));
+
+	error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp, 0, 0);
+	if (error)
+		return error;
+
+	/* Make sure the old pointer isn't garbage. */
+	old_value = be32_to_cpu(dip->di_next_unlinked);
+	if (!xfs_verify_agino_or_null(mp, agno, old_value)) {
+		error = -EFSCORRUPTED;
+		goto out;
+	}
+
+	/*
+	 * Since we're updating a linked list, we should never find that the
+	 * current pointer is the same as the new value, unless we're
+	 * terminating the list.
+	 */
+	*old_next_agino = old_value;
+	if (old_value == next_agino) {
+		if (next_agino != NULLAGINO)
+			error = -EFSCORRUPTED;
+		goto out;
+	}
+
+	/* Ok, update the new pointer. */
+	xfs_iunlink_update_dinode(tp, agno, XFS_INO_TO_AGINO(mp, ip->i_ino),
+			ibp, dip, &ip->i_imap, next_agino);
+	return 0;
+out:
+	xfs_trans_brelse(tp, ibp);
+	return error;
+}
+
 /*
  * This is called when the inode's link count goes to 0 or we are creating a
  * tmpfile via O_TMPFILE. In the case of a tmpfile, @ignore_linkcount will be
@@ -1960,14 +2039,11 @@ xfs_iunlink(
 {
 	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_agi		*agi;
-	struct xfs_dinode	*dip;
 	struct xfs_buf		*agibp;
-	struct xfs_buf		*ibp;
 	xfs_agino_t		next_agino;
 	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
 	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
 	short			bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
-	int			offset;
 	int			error;
 
 	ASSERT(VFS_I(ip)->i_mode != 0);
@@ -1989,29 +2065,17 @@ xfs_iunlink(
 		return -EFSCORRUPTED;
 
 	if (next_agino != NULLAGINO) {
+		xfs_agino_t	old_agino;
+
 		/*
-		 * There is already another inode in the bucket we need
-		 * to add ourselves to.  Add us at the front of the list.
-		 * Here we put the head pointer into our next pointer,
-		 * and then we fall through to point the head at us.
+		 * There is already another inode in the bucket, so point this
+		 * inode to the current head of the list.
 		 */
-		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
-				       0, 0);
+		error = xfs_iunlink_update_inode(tp, ip, agno, next_agino,
+				&old_agino);
 		if (error)
 			return error;
-
-		ASSERT(dip->di_next_unlinked == cpu_to_be32(NULLAGINO));
-		dip->di_next_unlinked = agi->agi_unlinked[bucket_index];
-		offset = ip->i_imap.im_boffset +
-			offsetof(xfs_dinode_t, di_next_unlinked);
-
-		/* need to recalc the inode CRC if appropriate */
-		xfs_dinode_calc_crc(mp, dip);
-
-		xfs_trans_inode_buf(tp, ibp);
-		xfs_trans_log_buf(tp, ibp, offset,
-				  (offset + sizeof(xfs_agino_t) - 1));
-		xfs_inobp_check(mp, ibp);
+		ASSERT(old_agino == NULLAGINO);
 	}
 
 	/* Point the head of the list to point to this inode. */
@@ -2028,9 +2092,7 @@ xfs_iunlink_remove(
 {
 	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_agi		*agi;
-	struct xfs_dinode	*dip;
 	struct xfs_buf		*agibp;
-	struct xfs_buf		*ibp;
 	struct xfs_buf		*last_ibp;
 	struct xfs_dinode	*last_dip = NULL;
 	xfs_ino_t		next_ino;
@@ -2038,8 +2100,6 @@ xfs_iunlink_remove(
 	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
 	xfs_agino_t		next_agino;
 	short			bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
-	int			offset;
-	int			last_offset = 0;
 	int			error;
 
 	/* Get the agi buffer first.  It ensures lock ordering on the list. */
@@ -2063,34 +2123,11 @@ xfs_iunlink_remove(
 		/*
 		 * We're at the head of the list.  Get the inode's on-disk
 		 * buffer to see if there is anyone after us on the list.
-		 * Only modify our next pointer if it is not already NULLAGINO.
-		 * This saves us the overhead of dealing with the buffer when
-		 * there is no need to change it.
 		 */
-		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
-				       0, 0);
-		if (error) {
-			xfs_warn(mp, "%s: xfs_imap_to_bp returned error %d.",
-				__func__, error);
+		error = xfs_iunlink_update_inode(tp, ip, agno, NULLAGINO,
+				&next_agino);
+		if (error)
 			return error;
-		}
-		next_agino = be32_to_cpu(dip->di_next_unlinked);
-		ASSERT(next_agino != 0);
-		if (next_agino != NULLAGINO) {
-			dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
-			offset = ip->i_imap.im_boffset +
-				offsetof(xfs_dinode_t, di_next_unlinked);
-
-			/* need to recalc the inode CRC if appropriate */
-			xfs_dinode_calc_crc(mp, dip);
-
-			xfs_trans_inode_buf(tp, ibp);
-			xfs_trans_log_buf(tp, ibp, offset,
-					  (offset + sizeof(xfs_agino_t) - 1));
-			xfs_inobp_check(mp, ibp);
-		} else {
-			xfs_trans_brelse(tp, ibp);
-		}
 
 		/* Point the head of the list to the next unlinked inode. */
 		error = xfs_iunlink_update_bucket(tp, agno, agibp, bucket_index,
@@ -2098,13 +2135,14 @@ xfs_iunlink_remove(
 		if (error)
 			return error;
 	} else {
+		struct xfs_imap	imap;
+		xfs_agino_t	prev_agino;
+
 		/*
 		 * We need to search the list for the inode being freed.
 		 */
 		last_ibp = NULL;
 		while (next_agino != agino) {
-			struct xfs_imap	imap;
-
 			if (last_ibp)
 				xfs_trans_brelse(tp, last_ibp);
 
@@ -2128,7 +2166,7 @@ xfs_iunlink_remove(
 				return error;
 			}
 
-			last_offset = imap.im_boffset;
+			prev_agino = next_agino;
 			next_agino = be32_to_cpu(last_dip->di_next_unlinked);
 			if (!xfs_verify_agino(mp, agno, next_agino)) {
 				XFS_CORRUPTION_ERROR(__func__,
@@ -2142,45 +2180,14 @@ xfs_iunlink_remove(
 		 * Now last_ibp points to the buffer previous to us on the
 		 * unlinked list.  Pull us from the list.
 		 */
-		error = xfs_imap_to_bp(mp, tp, &ip->i_imap, &dip, &ibp,
-				       0, 0);
-		if (error) {
-			xfs_warn(mp, "%s: xfs_imap_to_bp(2) returned error %d.",
-				__func__, error);
+		error = xfs_iunlink_update_inode(tp, ip, agno, NULLAGINO,
+				&next_agino);
+		if (error)
 			return error;
-		}
-		next_agino = be32_to_cpu(dip->di_next_unlinked);
-		ASSERT(next_agino != 0);
-		ASSERT(next_agino != agino);
-		if (next_agino != NULLAGINO) {
-			dip->di_next_unlinked = cpu_to_be32(NULLAGINO);
-			offset = ip->i_imap.im_boffset +
-				offsetof(xfs_dinode_t, di_next_unlinked);
-
-			/* need to recalc the inode CRC if appropriate */
-			xfs_dinode_calc_crc(mp, dip);
-
-			xfs_trans_inode_buf(tp, ibp);
-			xfs_trans_log_buf(tp, ibp, offset,
-					  (offset + sizeof(xfs_agino_t) - 1));
-			xfs_inobp_check(mp, ibp);
-		} else {
-			xfs_trans_brelse(tp, ibp);
-		}
-		/*
-		 * Point the previous inode on the list to the next inode.
-		 */
-		last_dip->di_next_unlinked = cpu_to_be32(next_agino);
-		ASSERT(next_agino != 0);
-		offset = last_offset + offsetof(xfs_dinode_t, di_next_unlinked);
-
-		/* need to recalc the inode CRC if appropriate */
-		xfs_dinode_calc_crc(mp, last_dip);
 
-		xfs_trans_inode_buf(tp, last_ibp);
-		xfs_trans_log_buf(tp, last_ibp, offset,
-				  (offset + sizeof(xfs_agino_t) - 1));
-		xfs_inobp_check(mp, last_ibp);
+		/* Point the previous inode on the list to the next inode. */
+		xfs_iunlink_update_dinode(tp, agno, prev_agino, last_ibp,
+				last_dip, &imap, next_agino);
 	}
 	return 0;
 }

fs/xfs/xfs_trace.h

@@ -3397,6 +3397,32 @@ TRACE_EVENT(xfs_iunlink_update_bucket,
 		  __entry->new_ptr)
 );
 
+TRACE_EVENT(xfs_iunlink_update_dinode,
+	TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_agino_t agino,
+		 xfs_agino_t old_ptr, xfs_agino_t new_ptr),
+	TP_ARGS(mp, agno, agino, old_ptr, new_ptr),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(xfs_agnumber_t, agno)
+		__field(xfs_agino_t, agino)
+		__field(xfs_agino_t, old_ptr)
+		__field(xfs_agino_t, new_ptr)
+	),
+	TP_fast_assign(
+		__entry->dev = mp->m_super->s_dev;
+		__entry->agno = agno;
+		__entry->agino = agino;
+		__entry->old_ptr = old_ptr;
+		__entry->new_ptr = new_ptr;
+	),
+	TP_printk("dev %d:%d agno %u agino 0x%x old 0x%x new 0x%x",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->agno,
+		  __entry->agino,
+		  __entry->old_ptr,
+		  __entry->new_ptr)
+);
+
 #endif /* _TRACE_XFS_H */
 
 #undef TRACE_INCLUDE_PATH