xfs: fix error handling at xfs_inumbers

From: Jie Liu <jeff.liu@oracle.com>

To fetch the file system number tables, we currently just ignore the
errors and proceed to loop over the next AG or bump agino to the next
chunk in case of btree operations failed, that is not properly because
those errors might hint us potential file system problems.

This patch rework xfs_inumbers() to handle the btree operation errors
as well as the loop conditions.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_itable.c

@@ -536,7 +536,7 @@ xfs_inumbers(
 	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, *lastino);
 	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, *lastino);
 	struct xfs_btree_cur	*cur = NULL;
-	xfs_buf_t		*agbp = NULL;
+	struct xfs_buf		*agbp = NULL;
 	struct xfs_inogrp	*buffer;
 	int			bcount;
 	int			left = *count;
@@ -550,61 +550,40 @@ xfs_inumbers(
 
 	bcount = MIN(left, (int)(PAGE_SIZE / sizeof(*buffer)));
 	buffer = kmem_alloc(bcount * sizeof(*buffer), KM_SLEEP);
-	while (left > 0 && agno < mp->m_sb.sb_agcount) {
+	do {
 		struct xfs_inobt_rec_incore	r;
 		int				stat;
 
-		if (agbp == NULL) {
+		if (!agbp) {
 			error = xfs_ialloc_read_agi(mp, NULL, agno, &agbp);
-			if (error) {
-				/*
-				 * If we can't read the AGI of this ag,
-				 * then just skip to the next one.
-				 */
-				ASSERT(cur == NULL);
-				agbp = NULL;
-				agno++;
-				agino = 0;
-				continue;
-			}
+			if (error)
+				break;
+
 			cur = xfs_inobt_init_cursor(mp, NULL, agbp, agno,
 						    XFS_BTNUM_INO);
 			error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_GE,
 						 &stat);
-			if (error) {
-				xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
-				cur = NULL;
-				xfs_buf_relse(agbp);
-				agbp = NULL;
-				/*
-				 * Move up the last inode in the current
-				 * chunk.  The lookup_ge will always get
-				 * us the first inode in the next chunk.
-				 */
-				agino += XFS_INODES_PER_CHUNK - 1;
-				continue;
-			}
+			if (error)
+				break;
+			if (!stat)
+				goto next_ag;
 		}
+
 		error = xfs_inobt_get_rec(cur, &r, &stat);
-		if (error || stat == 0) {
-			xfs_buf_relse(agbp);
-			agbp = NULL;
-			xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
-			cur = NULL;
-			agno++;
-			agino = 0;
-			continue;
-		}
+		if (error)
+			break;
+		if (!stat)
+			goto next_ag;
+
 		agino = r.ir_startino + XFS_INODES_PER_CHUNK - 1;
 		buffer[bufidx].xi_startino =
 			XFS_AGINO_TO_INO(mp, agno, r.ir_startino);
 		buffer[bufidx].xi_alloccount =
 			XFS_INODES_PER_CHUNK - r.ir_freecount;
 		buffer[bufidx].xi_allocmask = ~r.ir_free;
-		bufidx++;
-		left--;
-		if (bufidx == bcount) {
-			long written;
+		if (++bufidx == bcount) {
+			long	written;
+
 			error = formatter(ubuffer, buffer, bufidx, &written);
 			if (error)
 				break;
@@ -612,36 +591,40 @@ xfs_inumbers(
 			*count += bufidx;
 			bufidx = 0;
 		}
-		if (left) {
-			error = xfs_btree_increment(cur, 0, &stat);
-			if (error) {
-				xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
-				cur = NULL;
-				xfs_buf_relse(agbp);
-				agbp = NULL;
-				/*
-				 * The agino value has already been bumped.
-				 * Just try to skip up to it.
-				 */
-				agino += XFS_INODES_PER_CHUNK;
-				continue;
-			}
-		}
-	}
+		if (!--left)
+			break;
+
+		error = xfs_btree_increment(cur, 0, &stat);
+		if (error)
+			break;
+		if (stat)
+			continue;
+
+next_ag:
+		xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
+		cur = NULL;
+		xfs_buf_relse(agbp);
+		agbp = NULL;
+		agino = 0;
+	} while (++agno < mp->m_sb.sb_agcount);
+
 	if (!error) {
 		if (bufidx) {
-			long written;
+			long	written;
+
 			error = formatter(ubuffer, buffer, bufidx, &written);
 			if (!error)
 				*count += bufidx;
 		}
 		*lastino = XFS_AGINO_TO_INO(mp, agno, agino);
 	}
+
 	kmem_free(buffer);
 	if (cur)
 		xfs_btree_del_cursor(cur, (error ? XFS_BTREE_ERROR :
 					   XFS_BTREE_NOERROR));
 	if (agbp)
 		xfs_buf_relse(agbp);
+
 	return error;
 }