xfs: skip unallocated regions of inode chunks in xfs_ifree_cluster()

xfs_ifree_cluster() is called to mark all in-memory inodes and inode
buffers as stale. This occurs after we've removed the inobt records and
dropped any references of inobt data. xfs_ifree_cluster() uses the
starting inode number to walk the namespace of inodes expected for a
single chunk a cluster buffer at a time. The cluster buffer disk
addresses are calculated by decoding the sequential inode numbers
expected from the chunk.

The problem with this approach is that if the inode chunk being removed
is a sparse chunk, not all of the buffer addresses that are calculated
as part of this sequence may be inode clusters. Attempting to acquire
the buffer based on expected inode characterstics (i.e., cluster length)
can lead to errors and is generally incorrect.

We already use a couple variables to carry requisite state from
xfs_difree() to xfs_ifree_cluster(). Rather than add a third, define a
new internal structure to carry the existing parameters through these
functions. Add an alloc field that represents the physical allocation
bitmap of inodes in the chunk being removed. Modify xfs_ifree_cluster()
to check each inode against the bitmap and skip the clusters that were
never allocated as real inodes on disk.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 20 insertions, 8 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index d6ebc85192b7..11a8c28c47bd 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2239,9 +2239,9 @@ xfs_iunlink_remove(
  */
 STATIC int
 xfs_ifree_cluster(
-	xfs_inode_t	*free_ip,
-	xfs_trans_t	*tp,
-	xfs_ino_t	inum)
+	xfs_inode_t		*free_ip,
+	xfs_trans_t		*tp,
+	struct xfs_icluster	*xic)
 {
 	xfs_mount_t		*mp = free_ip->i_mount;
 	int			blks_per_cluster;
@@ -2254,13 +2254,26 @@ xfs_ifree_cluster(
 	xfs_inode_log_item_t	*iip;
 	xfs_log_item_t		*lip;
 	struct xfs_perag	*pag;
+	xfs_ino_t		inum;
 
+	inum = xic->first_ino;
 	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, inum));
 	blks_per_cluster = xfs_icluster_size_fsb(mp);
 	inodes_per_cluster = blks_per_cluster << mp->m_sb.sb_inopblog;
 	nbufs = mp->m_ialloc_blks / blks_per_cluster;
 
 	for (j = 0; j < nbufs; j++, inum += inodes_per_cluster) {
+		/*
+		 * The allocation bitmap tells us which inodes of the chunk were
+		 * physically allocated. Skip the cluster if an inode falls into
+		 * a sparse region.
+		 */
+		if ((xic->alloc & XFS_INOBT_MASK(inum - xic->first_ino)) == 0) {
+			ASSERT(((inum - xic->first_ino) %
+				inodes_per_cluster) == 0);
+			continue;
+		}
+
 		blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
 					 XFS_INO_TO_AGBNO(mp, inum));
 
@@ -2418,8 +2431,7 @@ xfs_ifree(
 	xfs_bmap_free_t	*flist)
 {
 	int			error;
-	int			delete;
-	xfs_ino_t		first_ino;
+	struct xfs_icluster	xic = { 0 };
 
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
 	ASSERT(ip->i_d.di_nlink == 0);
@@ -2435,7 +2447,7 @@ xfs_ifree(
 	if (error)
 		return error;
 
-	error = xfs_difree(tp, ip->i_ino, flist, &delete, &first_ino);
+	error = xfs_difree(tp, ip->i_ino, flist, &xic);
 	if (error)
 		return error;
 
@@ -2452,8 +2464,8 @@ xfs_ifree(
 	ip->i_d.di_gen++;
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
-	if (delete)
-		error = xfs_ifree_cluster(ip, tp, first_ino);
+	if (xic.deleted)
+		error = xfs_ifree_cluster(ip, tp, &xic);
 
 	return error;
 }