[PATCH 02/28] xfs: update free inode record logic to support sparse inode records

Brian Foster
2015-06-02T18:42:08Z

xfs_difree_inobt() uses logic in a couple places that assume inobt
records refer to fully allocated chunks. Specifically, the use of
mp->m_ialloc_inos can cause problems for inode chunks that are sparsely
allocated. Sparse inode chunks can, by definition, define a smaller
number of inodes than a full inode chunk.

Fix the logic that determines whether an inode record should be removed
from the inobt to use the ir_free mask rather than ir_freecount. Fix the
agi counters modification to use ir_freecount to add the actual number
of inodes freed rather than assuming a full inode chunk.

Also make sure that we preserve the behavior to not remove inode chunks
if the block size is large enough for multiple inode chunks (e.g.,
bsize=64k, isize=512). This behavior was previously implicit in that in
such configurations, ir.freecount of a single record never matches
m_ialloc_inos. Hence, add some comments as well.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
libxfs/xfs_ialloc.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/libxfs/xfs_ialloc.c b/libxfs/xfs_ialloc.c
index a1cf1dd..673c0a7 100644
--- a/libxfs/xfs_ialloc.c
+++ b/libxfs/xfs_ialloc.c
@@ -1503,10 +1503,13 @@ xfs_difree_inobt(
rec.ir_freecount++;

/*
- * When an inode cluster is free, it becomes eligible for removal
+ * When an inode chunk is free, it becomes eligible for removal. Don't
+ * remove the chunk if the block size is large enough for multiple inode
+ * chunks (that might not be free).
*/
if (!(mp->m_flags & XFS_MOUNT_IKEEP) &&
- (rec.ir_freecount == mp->m_ialloc_inos)) {
+ rec.ir_free == XFS_INOBT_ALL_FREE &&
+ mp->m_sb.sb_inopblock <= XFS_INODES_PER_CHUNK) {

*deleted = 1;
*first_ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino);
@@ -1516,7 +1519,7 @@ xfs_difree_inobt(
* AGI and Superblock inode counts, and mark the disk space
* to be freed when the transaction is committed.
*/
- ilen = mp->m_ialloc_inos;
+ ilen = rec.ir_freecount;
be32_add_cpu(&agi->agi_count, -ilen);
be32_add_cpu(&agi->agi_freecount, -(ilen - 1));
xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);
@@ -1636,8 +1639,13 @@ xfs_difree_finobt(
* free inode. Hence, if all of the inodes are free and we aren't
* keeping inode chunks permanently on disk, remove the record.
* Otherwise, update the record with the new information.
+ *
+ * Note that we currently can't free chunks when the block size is large
+ * enough for multiple chunks. Leave the finobt record to remain in sync
+ * with the inobt.
*/
- if (rec.ir_freecount == mp->m_ialloc_inos &&
+ if (rec.ir_free == XFS_INOBT_ALL_FREE &&
+ mp->m_sb.sb_inopblock <= XFS_INODES_PER_CHUNK &&
!(mp->m_flags & XFS_MOUNT_IKEEP)) {
error = xfs_btree_delete(cur, &i);
if (error)