[PATCH AUTOSEL for 4.9 262/281] xfs: fix up agi unlinked list reservations

[Sasha Levin]

From: Brian Foster <bfoster@xxxxxxxxxx>

[ Upstream commit e8341d9f6348640dff01d8c4a33695dc82bab5a3 ]

The current AGI unlinked list addition and removal reservations do
not reflect the worst case log usage. An unlinked list removal can
log up to two on-disk inode clusters but only includes reservation
for one. An unlinked list addition logs the on-disk cluster but
includes reservation for an in-core inode.

Update the AGI unlinked list reservation helpers to calculate the
correct worst case reservation for the associated operations.

Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_trans_resv.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c
index 7f685401728a..6c85a131827f 100644
--- a/fs/xfs/libxfs/xfs_trans_resv.c
+++ b/fs/xfs/libxfs/xfs_trans_resv.c
@@ -282,13 +282,14 @@ xfs_calc_rename_reservation(
  * For removing an inode from unlinked list at first, we can modify:
  *    the agi hash list and counters: sector size
  *    the on disk inode before ours in the agi hash list: inode cluster size
+ *    the on disk inode in the agi hash list: inode cluster size
  */
 STATIC uint
 xfs_calc_iunlink_remove_reservation(
 	struct xfs_mount        *mp)
 {
 	return xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) +
-	       max_t(uint, XFS_FSB_TO_B(mp, 1), mp->m_inode_cluster_size);
+	       2 * max_t(uint, XFS_FSB_TO_B(mp, 1), mp->m_inode_cluster_size);
 }
 
 /*
@@ -320,13 +321,13 @@ xfs_calc_link_reservation(
 /*
  * For adding an inode to unlinked list we can modify:
  *    the agi hash list: sector size
- *    the unlinked inode: inode size
+ *    the on disk inode: inode cluster size
  */
 STATIC uint
 xfs_calc_iunlink_add_reservation(xfs_mount_t *mp)
 {
 	return xfs_calc_buf_res(1, mp->m_sb.sb_sectsize) +
-		xfs_calc_inode_res(mp, 1);
+		max_t(uint, XFS_FSB_TO_B(mp, 1), mp->m_inode_cluster_size);
 }
 
 /*
-- 
2.14.1