xfs: drop iolock from reclaim context to appease lockdep
PATCH 1/1 xfs: drop iolock from reclaim context to appease lockdep
Lockdep complains about use of the iolock in inode reclaim context because it doesn't understand that reclaim has the last reference to the inode, and thus an iolock->reclaim->iolock deadlock is not possible.
The iolock is technically not necessary in xfs_inactive() and was only added to appease an assert in xfs_free_eofblocks(), which can be called from other non-reclaim contexts. Therefore, just kill the assert and drop the use of the iolock from reclaim context to quiet lockdep.
--- fs/xfs/xfs_bmap_util.c | 8 +++----- fs/xfs/xfs_inode.c | 9 +++++---- 2 files changed, 8 insertions(+), 9 deletions(-)
fs/xfs/xfs_bmap_util.c +3 -5
@@ -903,9 +903,9 @@ xfs_can_free_eofblocks(struct xfs_inode *ip, bool force) }/* -* This is called by xfs_inactive to free any blocks beyond eof -* when the link count isn't zero and by xfs_dm_punch_hole() when -* punching a hole to EOF. +* This is called to free any blocks beyond eof. The caller must hold +* IOLOCK_EXCL unless we are in the inode reclaim path and have the only +* reference to the inode. */ int xfs_free_eofblocks(
@@ -920,8 +920,6 @@ xfs_free_eofblocks(struct xfs_bmbt_irec imap;struct xfs_mount *mp = ip->i_mount; -ASSERT (xfs_isilocked (ip,XFS_IOLOCK_EXCL )); -/* * Figure out if there are any blocks beyond the end * of the file. If not, then there is nothing to do.
fs/xfs/xfs_inode.c +5 -4
@@ -1906,12 +1906,13 @@ xfs_inactive(* force is true because we are evicting an inode from the * cache. Post-eof blocks must be freed, lest we end up with * broken free space accounting. +* +* Note: don't bother with iolock here since lockdep complains +* about acquiring it in reclaim context. We have the only +* reference to the inode at this point anyways. */ -if (xfs_can_free_eofblocks (ip, true)) { -xfs_ilock (ip,XFS_IOLOCK_EXCL ); +if (xfs_can_free_eofblocks (ip, true))xfs_free_eofblocks (ip); -xfs_iunlock (ip,XFS_IOLOCK_EXCL ); - }return ; }
Signature · 1 line
2.7.4
Quoted 5 lines · Brian Foster
Lockdep complains about use of the iolock in inode reclaim context because it doesn't understand that reclaim has the last reference to the inode, and thus an
iolock->reclaim->iolockdeadlock is not possible.
Quoted 7 lines
The iolock is technically not necessary in
xfs_inactive()and was only added to appease an assert inxfs_free_eofblocks(), which can be called from other non-reclaim contexts. Therefore, just kill the assert and drop the use of the iolock from reclaim context to quiet lockdep.Signed-off-by Brian Foster <[email protected]>
Looks ok, hasn't started any new fires...
--D
Quoted 60 lines
--- fs/xfs/xfs_bmap_util.c | 8 +++----- fs/xfs/xfs_inode.c | 9 +++++---- 2 files changed, 8 insertions(+), 9 deletions(-)fs/xfs/xfs_bmap_util.c +3
-5@@ -903,9 +903,9 @@ xfs_can_free_eofblocks(struct xfs_inode *ip, bool force) }/* -* This is called by xfs_inactive to free any blocks beyond eof -* when the link count isn't zero and by xfs_dm_punch_hole() when -* punching a hole to EOF. +* This is called to free any blocks beyond eof. The caller must hold +* IOLOCK_EXCL unless we are in the inode reclaim path and have the only +* reference to the inode. */ int xfs_free_eofblocks(@@ -920,8 +920,6 @@ xfs_free_eofblocks(struct xfs_bmbt_irec imap;struct xfs_mount *mp = ip->i_mount; -ASSERT (xfs_isilocked (ip,XFS_IOLOCK_EXCL )); -/* * Figure out if there are any blocks beyond the end * of the file. If not, then there is nothing to do. fs/xfs/xfs_inode.c +5
-4@@ -1906,12 +1906,13 @@ xfs_inactive(* force is true because we are evicting an inode from the * cache. Post-eof blocks must be freed, lest we end up with * broken free space accounting. +* +* Note: don't bother with iolock here since lockdep complains +* about acquiring it in reclaim context. We have the only +* reference to the inode at this point anyways. */ -if (xfs_can_free_eofblocks (ip, true)) { -xfs_ilock (ip,XFS_IOLOCK_EXCL ); +if (xfs_can_free_eofblocks (ip, true))xfs_free_eofblocks (ip); -xfs_iunlock (ip,XFS_IOLOCK_EXCL ); - }return ; }Signature · 6 lines
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