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xfs: log item flags are racy

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The log item flags contain a field that is protected by the AIL
lock - the XFS_LI_IN_AIL flag. We use non-atomic RMW operations to
set and clear these flags, but most of the updates and checks are
not done with the AIL lock held and so are susceptible to update
races.

Fix this by changing the log item flags to use atomic bitops rather
than be reliant on the AIL lock for update serialisation.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Dave Chinner
2018-05-09 07:47:34 -07:00
committed by Darrick J. Wong
parent 52101dfe56
commit 22525c17ed
19 changed files with 52 additions and 48 deletions
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19
fs/xfs/xfs_trans.h
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@@ -48,7 +48,7 @@ typedef struct xfs_log_item {
struct xfs_mount *li_mountp; /* ptr to fs mount */
struct xfs_ail *li_ailp; /* ptr to AIL */
uint li_type; /* item type */
uint li_flags; /* misc flags */
unsigned long li_flags; /* misc flags */
struct xfs_buf *li_buf; /* real buffer pointer */
struct list_head li_bio_list; /* buffer item list */
void (*li_cb)(struct xfs_buf *,
@@ -64,14 +64,19 @@ typedef struct xfs_log_item {
xfs_lsn_t li_seq; /* CIL commit seq */
} xfs_log_item_t;
#define XFS_LI_IN_AIL 0x1
#define XFS_LI_ABORTED 0x2
#define XFS_LI_FAILED 0x4
/*
* li_flags use the (set/test/clear)_bit atomic interfaces because updates can
* race with each other and we don't want to have to use the AIL lock to
* serialise all updates.
*/
#define XFS_LI_IN_AIL 0
#define XFS_LI_ABORTED 1
#define XFS_LI_FAILED 2
#define XFS_LI_FLAGS \
{ XFS_LI_IN_AIL, "IN_AIL" }, \
{ XFS_LI_ABORTED, "ABORTED" }, \
{ XFS_LI_FAILED, "FAILED" }
{ (1 << XFS_LI_IN_AIL), "IN_AIL" }, \
{ (1 << XFS_LI_ABORTED), "ABORTED" }, \
{ (1 << XFS_LI_FAILED), "FAILED" }
struct xfs_item_ops {
void (*iop_size)(xfs_log_item_t *, int *, int *);