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xfs: Reference count per-ag structures

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Reference count the per-ag structures to ensure that we keep get/put
pairs balanced. Assert that the reference counts are zero at unmount
time to catch leaks. In future, reference counts will enable us to
safely remove perag structures by allowing us to detect when they
are no longer in use.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
This commit is contained in:
Dave Chinner 2010-01-11 11:47:45 +00:00 committed by Alex Elder
parent 1c1c6ebcf5
commit aed3bb90ab
3 changed files with 12 additions and 4 deletions
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4
fs/xfs/xfs_ag.h
View File

@ -196,8 +196,8 @@ typedef struct xfs_perag_busy {
#define XFS_PAGB_NUM_SLOTS 128
#endif
typedef struct xfs_perag
{
typedef struct xfs_perag {
atomic_t pag_ref; /* perag reference count */
char pagf_init; /* this agf's entry is initialized */
char pagi_init; /* this agi's entry is initialized */
char pagf_metadata; /* the agf is preferred to be metadata */

1
fs/xfs/xfs_mount.c
View File

@ -215,6 +215,7 @@ xfs_free_perag(
for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
spin_lock(&mp->m_perag_lock);
pag = radix_tree_delete(&mp->m_perag_tree, agno);
ASSERT(atomic_read(&pag->pag_ref) == 0);
spin_unlock(&mp->m_perag_lock);
ASSERT(pag);
kmem_free(pag->pagb_list);

11
fs/xfs/xfs_mount.h
View File

@ -384,7 +384,7 @@ xfs_daddr_to_agbno(struct xfs_mount *mp, xfs_daddr_t d)
}
/*
* perag get/put wrappers for eventual ref counting
* perag get/put wrappers for ref counting
*/
static inline struct xfs_perag *
xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
@ -393,6 +393,12 @@ xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
spin_lock(&mp->m_perag_lock);
pag = radix_tree_lookup(&mp->m_perag_tree, agno);
if (pag) {
ASSERT(atomic_read(&pag->pag_ref) >= 0);
/* catch leaks in the positive direction during testing */
ASSERT(atomic_read(&pag->pag_ref) < 1000);
atomic_inc(&pag->pag_ref);
}
spin_unlock(&mp->m_perag_lock);
return pag;
}
@ -400,7 +406,8 @@ xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno)
static inline void
xfs_perag_put(struct xfs_perag *pag)
{
/* nothing to see here, move along */
ASSERT(atomic_read(&pag->pag_ref) > 0);
atomic_dec(&pag->pag_ref);
}
/*