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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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4
fs/xfs/xfs_bmap_item.c
View File

@ -160,7 +160,7 @@ STATIC void
xfs_bui_item_unlock(
struct xfs_log_item *lip)
{
if (lip->li_flags & XFS_LI_ABORTED)
if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
xfs_bui_release(BUI_ITEM(lip));
}
@ -305,7 +305,7 @@ xfs_bud_item_unlock(
{
struct xfs_bud_log_item *budp = BUD_ITEM(lip);
if (lip->li_flags & XFS_LI_ABORTED) {
if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
xfs_bui_release(budp->bud_buip);
kmem_zone_free(xfs_bud_zone, budp);
}

4
fs/xfs/xfs_buf_item.c
View File

@ -568,13 +568,15 @@ xfs_buf_item_unlock(
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
struct xfs_buf *bp = bip->bli_buf;
bool aborted = !!(lip->li_flags & XFS_LI_ABORTED);
bool aborted;
bool hold = !!(bip->bli_flags & XFS_BLI_HOLD);
bool dirty = !!(bip->bli_flags & XFS_BLI_DIRTY);
#if defined(DEBUG) || defined(XFS_WARN)
bool ordered = !!(bip->bli_flags & XFS_BLI_ORDERED);
#endif
aborted = test_bit(XFS_LI_ABORTED, &lip->li_flags);
/* Clear the buffer's association with this transaction. */
bp->b_transp = NULL;

7
fs/xfs/xfs_dquot.c
View File

@ -913,9 +913,9 @@ xfs_qm_dqflush_done(
* since it's cheaper, and then we recheck while
* holding the lock before removing the dquot from the AIL.
*/
if ((lip->li_flags & XFS_LI_IN_AIL) &&
if (test_bit(XFS_LI_IN_AIL, &lip->li_flags) &&
((lip->li_lsn == qip->qli_flush_lsn) ||
(lip->li_flags & XFS_LI_FAILED))) {
test_bit(XFS_LI_FAILED, &lip->li_flags))) {
/* xfs_trans_ail_delete() drops the AIL lock. */
spin_lock(&ailp->ail_lock);
@ -926,8 +926,7 @@ xfs_qm_dqflush_done(
* Clear the failed state since we are about to drop the
* flush lock
*/
if (lip->li_flags & XFS_LI_FAILED)
xfs_clear_li_failed(lip);
xfs_clear_li_failed(lip);
spin_unlock(&ailp->ail_lock);
}
}

2
fs/xfs/xfs_dquot_item.c
View File

@ -173,7 +173,7 @@ xfs_qm_dquot_logitem_push(
* The buffer containing this item failed to be written back
* previously. Resubmit the buffer for IO
*/
if (lip->li_flags & XFS_LI_FAILED) {
if (test_bit(XFS_LI_FAILED, &lip->li_flags)) {
if (!xfs_buf_trylock(bp))
return XFS_ITEM_LOCKED;

4
fs/xfs/xfs_extfree_item.c
View File

@ -168,7 +168,7 @@ STATIC void
xfs_efi_item_unlock(
struct xfs_log_item *lip)
{
if (lip->li_flags & XFS_LI_ABORTED)
if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
xfs_efi_release(EFI_ITEM(lip));
}
@ -402,7 +402,7 @@ xfs_efd_item_unlock(
{
struct xfs_efd_log_item *efdp = EFD_ITEM(lip);
if (lip->li_flags & XFS_LI_ABORTED) {
if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
xfs_efi_release(efdp->efd_efip);
xfs_efd_item_free(efdp);
}

3
fs/xfs/xfs_icache.c
View File

@ -107,7 +107,8 @@ xfs_inode_free_callback(
xfs_idestroy_fork(ip, XFS_COW_FORK);
if (ip->i_itemp) {
ASSERT(!(ip->i_itemp->ili_item.li_flags & XFS_LI_IN_AIL));
ASSERT(!test_bit(XFS_LI_IN_AIL,
&ip->i_itemp->ili_item.li_flags));
xfs_inode_item_destroy(ip);
ip->i_itemp = NULL;
}

2
fs/xfs/xfs_icreate_item.c
View File

@ -91,7 +91,7 @@ xfs_icreate_item_unlock(
{
struct xfs_icreate_item *icp = ICR_ITEM(lip);
if (icp->ic_item.li_flags & XFS_LI_ABORTED)
if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
kmem_zone_free(xfs_icreate_zone, icp);
return;
}

4
fs/xfs/xfs_inode.c
View File

@ -498,7 +498,7 @@ again:
if (!try_lock) {
for (j = (i - 1); j >= 0 && !try_lock; j--) {
lp = (xfs_log_item_t *)ips[j]->i_itemp;
if (lp && (lp->li_flags & XFS_LI_IN_AIL))
if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags))
try_lock++;
}
}
@ -598,7 +598,7 @@ xfs_lock_two_inodes(
* and try again.
*/
lp = (xfs_log_item_t *)ip0->i_itemp;
if (lp && (lp->li_flags & XFS_LI_IN_AIL)) {
if (lp && test_bit(XFS_LI_IN_AIL, &lp->li_flags)) {
if (!xfs_ilock_nowait(ip1, xfs_lock_inumorder(ip1_mode, 1))) {
xfs_iunlock(ip0, ip0_mode);
if ((++attempts % 5) == 0)

8
fs/xfs/xfs_inode_item.c
View File

@ -518,7 +518,7 @@ xfs_inode_item_push(
* The buffer containing this item failed to be written back
* previously. Resubmit the buffer for IO.
*/
if (lip->li_flags & XFS_LI_FAILED) {
if (test_bit(XFS_LI_FAILED, &lip->li_flags)) {
if (!xfs_buf_trylock(bp))
return XFS_ITEM_LOCKED;
@ -729,14 +729,14 @@ xfs_iflush_done(
*/
iip = INODE_ITEM(blip);
if ((iip->ili_logged && blip->li_lsn == iip->ili_flush_lsn) ||
(blip->li_flags & XFS_LI_FAILED))
test_bit(XFS_LI_FAILED, &blip->li_flags))
need_ail++;
}
/* make sure we capture the state of the initial inode. */
iip = INODE_ITEM(lip);
if ((iip->ili_logged && lip->li_lsn == iip->ili_flush_lsn) ||
lip->li_flags & XFS_LI_FAILED)
test_bit(XFS_LI_FAILED, &lip->li_flags))
need_ail++;
/*
@ -803,7 +803,7 @@ xfs_iflush_abort(
xfs_inode_log_item_t *iip = ip->i_itemp;
if (iip) {
if (iip->ili_item.li_flags & XFS_LI_IN_AIL) {
if (test_bit(XFS_LI_IN_AIL, &iip->ili_item.li_flags)) {
xfs_trans_ail_remove(&iip->ili_item,
stale ? SHUTDOWN_LOG_IO_ERROR :
SHUTDOWN_CORRUPT_INCORE);

2
fs/xfs/xfs_log.c
View File

@ -2132,7 +2132,7 @@ xlog_print_trans(
xfs_warn(mp, "log item: ");
xfs_warn(mp, " type = 0x%x", lip->li_type);
xfs_warn(mp, " flags = 0x%x", lip->li_flags);
xfs_warn(mp, " flags = 0x%lx", lip->li_flags);
if (!lv)
continue;
xfs_warn(mp, " niovecs = %d", lv->lv_niovecs);

2
fs/xfs/xfs_qm.c
View File

@ -173,7 +173,7 @@ xfs_qm_dqpurge(
ASSERT(atomic_read(&dqp->q_pincount) == 0);
ASSERT(XFS_FORCED_SHUTDOWN(mp) ||
!(dqp->q_logitem.qli_item.li_flags & XFS_LI_IN_AIL));
!test_bit(XFS_LI_IN_AIL, &dqp->q_logitem.qli_item.li_flags));
xfs_dqfunlock(dqp);
xfs_dqunlock(dqp);

4
fs/xfs/xfs_refcount_item.c
View File

@ -159,7 +159,7 @@ STATIC void
xfs_cui_item_unlock(
struct xfs_log_item *lip)
{
if (lip->li_flags & XFS_LI_ABORTED)
if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
xfs_cui_release(CUI_ITEM(lip));
}
@ -310,7 +310,7 @@ xfs_cud_item_unlock(
{
struct xfs_cud_log_item *cudp = CUD_ITEM(lip);
if (lip->li_flags & XFS_LI_ABORTED) {
if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
xfs_cui_release(cudp->cud_cuip);
kmem_zone_free(xfs_cud_zone, cudp);
}

4
fs/xfs/xfs_rmap_item.c
View File

@ -158,7 +158,7 @@ STATIC void
xfs_rui_item_unlock(
struct xfs_log_item *lip)
{
if (lip->li_flags & XFS_LI_ABORTED)
if (test_bit(XFS_LI_ABORTED, &lip->li_flags))
xfs_rui_release(RUI_ITEM(lip));
}
@ -331,7 +331,7 @@ xfs_rud_item_unlock(
{
struct xfs_rud_log_item *rudp = RUD_ITEM(lip);
if (lip->li_flags & XFS_LI_ABORTED) {
if (test_bit(XFS_LI_ABORTED, &lip->li_flags)) {
xfs_rui_release(rudp->rud_ruip);
kmem_zone_free(xfs_rud_zone, rudp);
}

6
fs/xfs/xfs_trace.h
View File

@ -442,7 +442,7 @@ DECLARE_EVENT_CLASS(xfs_buf_item_class,
__field(int, bli_refcount)
__field(unsigned, bli_flags)
__field(void *, li_desc)
__field(unsigned, li_flags)
__field(unsigned long, li_flags)
),
TP_fast_assign(
__entry->dev = bip->bli_buf->b_target->bt_dev;
@ -1018,7 +1018,7 @@ DECLARE_EVENT_CLASS(xfs_log_item_class,
__field(dev_t, dev)
__field(void *, lip)
__field(uint, type)
__field(uint, flags)
__field(unsigned long, flags)
__field(xfs_lsn_t, lsn)
),
TP_fast_assign(
@ -1070,7 +1070,7 @@ DECLARE_EVENT_CLASS(xfs_ail_class,
__field(dev_t, dev)
__field(void *, lip)
__field(uint, type)
__field(uint, flags)
__field(unsigned long, flags)
__field(xfs_lsn_t, old_lsn)
__field(xfs_lsn_t, new_lsn)
),

4
fs/xfs/xfs_trans.c
View File

@ -792,7 +792,7 @@ xfs_trans_free_items(
if (commit_lsn != NULLCOMMITLSN)
lip->li_ops->iop_committing(lip, commit_lsn);
if (abort)
lip->li_flags |= XFS_LI_ABORTED;
set_bit(XFS_LI_ABORTED, &lip->li_flags);
lip->li_ops->iop_unlock(lip);
xfs_trans_free_item_desc(lidp);
@ -863,7 +863,7 @@ xfs_trans_committed_bulk(
xfs_lsn_t item_lsn;
if (aborted)
lip->li_flags |= XFS_LI_ABORTED;
set_bit(XFS_LI_ABORTED, &lip->li_flags);
item_lsn = lip->li_ops->iop_committed(lip, commit_lsn);
/* item_lsn of -1 means the item needs no further processing */

19
fs/xfs/xfs_trans.h
View File

@ -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 *);

9
fs/xfs/xfs_trans_ail.c
View File

@ -46,7 +46,7 @@ xfs_ail_check(
/*
* Check the next and previous entries are valid.
*/
ASSERT((lip->li_flags & XFS_LI_IN_AIL) != 0);
ASSERT(test_bit(XFS_LI_IN_AIL, &lip->li_flags));
prev_lip = list_entry(lip->li_ail.prev, xfs_log_item_t, li_ail);
if (&prev_lip->li_ail != &ailp->ail_head)
ASSERT(XFS_LSN_CMP(prev_lip->li_lsn, lip->li_lsn) <= 0);
@ -684,7 +684,7 @@ xfs_trans_ail_update_bulk(
for (i = 0; i < nr_items; i++) {
struct xfs_log_item *lip = log_items[i];
if (lip->li_flags & XFS_LI_IN_AIL) {
if (test_and_set_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
/* check if we really need to move the item */
if (XFS_LSN_CMP(lsn, lip->li_lsn) <= 0)
continue;
@ -694,7 +694,6 @@ xfs_trans_ail_update_bulk(
if (mlip == lip)
mlip_changed = 1;
} else {
lip->li_flags |= XFS_LI_IN_AIL;
trace_xfs_ail_insert(lip, 0, lsn);
}
lip->li_lsn = lsn;
@ -725,7 +724,7 @@ xfs_ail_delete_one(
trace_xfs_ail_delete(lip, mlip->li_lsn, lip->li_lsn);
xfs_ail_delete(ailp, lip);
xfs_clear_li_failed(lip);
lip->li_flags &= ~XFS_LI_IN_AIL;
clear_bit(XFS_LI_IN_AIL, &lip->li_flags);
lip->li_lsn = 0;
return mlip == lip;
@ -761,7 +760,7 @@ xfs_trans_ail_delete(
struct xfs_mount *mp = ailp->ail_mount;
bool mlip_changed;
if (!(lip->li_flags & XFS_LI_IN_AIL)) {
if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
spin_unlock(&ailp->ail_lock);
if (!XFS_FORCED_SHUTDOWN(mp)) {
xfs_alert_tag(mp, XFS_PTAG_AILDELETE,

2
fs/xfs/xfs_trans_buf.c
View File

@ -442,7 +442,7 @@ xfs_trans_brelse(
ASSERT(bp->b_pincount == 0);
***/
ASSERT(atomic_read(&bip->bli_refcount) == 0);
ASSERT(!(bip->bli_item.li_flags & XFS_LI_IN_AIL));
ASSERT(!test_bit(XFS_LI_IN_AIL, &bip->bli_item.li_flags));
ASSERT(!(bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF));
xfs_buf_item_relse(bp);
}

10
fs/xfs/xfs_trans_priv.h
View File

@ -119,7 +119,7 @@ xfs_trans_ail_remove(
spin_lock(&ailp->ail_lock);
/* xfs_trans_ail_delete() drops the AIL lock */
if (lip->li_flags & XFS_LI_IN_AIL)
if (test_bit(XFS_LI_IN_AIL, &lip->li_flags))
xfs_trans_ail_delete(ailp, lip, shutdown_type);
else
spin_unlock(&ailp->ail_lock);
@ -171,11 +171,10 @@ xfs_clear_li_failed(
{
struct xfs_buf *bp = lip->li_buf;
ASSERT(lip->li_flags & XFS_LI_IN_AIL);
ASSERT(test_bit(XFS_LI_IN_AIL, &lip->li_flags));
lockdep_assert_held(&lip->li_ailp->ail_lock);
if (lip->li_flags & XFS_LI_FAILED) {
lip->li_flags &= ~XFS_LI_FAILED;
if (test_and_clear_bit(XFS_LI_FAILED, &lip->li_flags)) {
lip->li_buf = NULL;
xfs_buf_rele(bp);
}
@ -188,9 +187,8 @@ xfs_set_li_failed(
{
lockdep_assert_held(&lip->li_ailp->ail_lock);
if (!(lip->li_flags & XFS_LI_FAILED)) {
if (!test_and_set_bit(XFS_LI_FAILED, &lip->li_flags)) {
xfs_buf_hold(bp);
lip->li_flags |= XFS_LI_FAILED;
lip->li_buf = bp;
}
}