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xfs: provide a inode iolock lockdep class 

The XFS iolock needs to be re-initialised to a new lock class before
it enters reclaim to prevent lockdep false positives. Unfortunately,
this is not sufficient protection as inodes in the XFS_IRECLAIMABLE
state can be recycled and not re-initialised before being reused.

We need to re-initialise the lock state when transfering out of
XFS_IRECLAIMABLE state to XFS_INEW, but we need to keep the same
class as if the inode was just allocated. Hence we need a specific
lockdep class variable for the iolock so that both initialisations
use the same class.

While there, add a specific class for inodes in the reclaim state so
that it is easy to tell from lockdep reports what state the inode
was in that generated the report.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Dave Chinner 2010-12-23 11:57:13 +11:00 committed by Dave Chinner
parent 489a150f64
commit dcfcf20512
3 changed files with 23 additions and 0 deletions
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2
fs/xfs/linux-2.6/xfs_super.c
View File

@ -1118,6 +1118,8 @@ xfs_fs_evict_inode(
*/
ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
lockdep_set_class_and_name(&ip->i_iolock.mr_lock,
&xfs_iolock_reclaimable, "xfs_iolock_reclaimable");
xfs_inactive(ip);
}

19
fs/xfs/xfs_iget.c
View File

@ -42,6 +42,17 @@
#include "xfs_trace.h"
/*
* Define xfs inode iolock lockdep classes. We need to ensure that all active
* inodes are considered the same for lockdep purposes, including inodes that
* are recycled through the XFS_IRECLAIMABLE state. This is the the only way to
* guarantee the locks are considered the same when there are multiple lock
* initialisation siteѕ. Also, define a reclaimable inode class so it is
* obvious in lockdep reports which class the report is against.
*/
static struct lock_class_key xfs_iolock_active;
struct lock_class_key xfs_iolock_reclaimable;
/*
* Allocate and initialise an xfs_inode.
*/
@ -71,6 +82,8 @@ xfs_inode_alloc(
ASSERT(completion_done(&ip->i_flush));
mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
lockdep_set_class_and_name(&ip->i_iolock.mr_lock,
&xfs_iolock_active, "xfs_iolock_active");
/* initialise the xfs inode */
ip->i_ino = ino;
@ -218,6 +231,12 @@ xfs_iget_cache_hit(
ip->i_flags |= XFS_INEW;
__xfs_inode_clear_reclaim_tag(mp, pag, ip);
inode->i_state = I_NEW;
ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
lockdep_set_class_and_name(&ip->i_iolock.mr_lock,
&xfs_iolock_active, "xfs_iolock_active");
spin_unlock(&ip->i_flags_lock);
write_unlock(&pag->pag_ici_lock);
} else {

2
fs/xfs/xfs_inode.h
View File

@ -438,6 +438,8 @@ static inline void xfs_ifunlock(xfs_inode_t *ip)
#define XFS_IOLOCK_DEP(flags) (((flags) & XFS_IOLOCK_DEP_MASK) >> XFS_IOLOCK_SHIFT)
#define XFS_ILOCK_DEP(flags) (((flags) & XFS_ILOCK_DEP_MASK) >> XFS_ILOCK_SHIFT)
extern struct lock_class_key xfs_iolock_reclaimable;
/*
* Flags for xfs_itruncate_start().
*/