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[XFS] Fix double free of log tickets 

When an I/O error occurs during an intermediate commit on a rolling
transaction, xfs_trans_commit() will free the transaction structure
and the related ticket. However, the duplicate transaction that
gets used as the transaction continues still contains a pointer
to the ticket. Hence when the duplicate transaction is cancelled
and freed, we free the ticket a second time.

Add reference counting to the ticket so that we hold an extra
reference to the ticket over the transaction commit. We drop the
extra reference once we have checked that the transaction commit
did not return an error, thus avoiding a double free on commit
error.

Credit to Nick Piggin for tripping over the problem.

SGI-PV: 989741

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
This commit is contained in:
Dave Chinner 2008-11-17 17:37:10 +11:00 committed by Lachlan McIlroy
parent 6307091fe6
commit cc09c0dc57
8 changed files with 66 additions and 19 deletions
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10
fs/xfs/xfs_bmap.c
View File

@ -4292,9 +4292,15 @@ xfs_bmap_finish(
* We have a new transaction, so we should return committed=1,
* even though we're returning an error.
*/
if (error) {
if (error)
return error;
}
/*
* transaction commit worked ok so we can drop the extra ticket
* reference that we gained in xfs_trans_dup()
*/
xfs_log_ticket_put(ntp->t_ticket);
if ((error = xfs_trans_reserve(ntp, 0, logres, 0, XFS_TRANS_PERM_LOG_RES,
logcount)))
return error;

10
fs/xfs/xfs_inode.c
View File

@ -1782,8 +1782,14 @@ xfs_itruncate_finish(
xfs_trans_ijoin(ntp, ip, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
xfs_trans_ihold(ntp, ip);
if (!error)
error = xfs_trans_reserve(ntp, 0,
if (error)
return error;
/*
* transaction commit worked ok so we can drop the extra ticket
* reference that we gained in xfs_trans_dup()
*/
xfs_log_ticket_put(ntp->t_ticket);
error = xfs_trans_reserve(ntp, 0,
XFS_ITRUNCATE_LOG_RES(mp), 0,
XFS_TRANS_PERM_LOG_RES,
XFS_ITRUNCATE_LOG_COUNT);

39
fs/xfs/xfs_log.c
View File

@ -100,12 +100,11 @@ STATIC void xlog_ungrant_log_space(xlog_t *log,
/* local ticket functions */
STATIC xlog_ticket_t *xlog_ticket_get(xlog_t *log,
STATIC xlog_ticket_t *xlog_ticket_alloc(xlog_t *log,
int unit_bytes,
int count,
char clientid,
uint flags);
STATIC void xlog_ticket_put(xlog_t *log, xlog_ticket_t *ticket);
#if defined(DEBUG)
STATIC void xlog_verify_dest_ptr(xlog_t *log, __psint_t ptr);
@ -360,7 +359,7 @@ xfs_log_done(xfs_mount_t *mp,
*/
xlog_trace_loggrant(log, ticket, "xfs_log_done: (non-permanent)");
xlog_ungrant_log_space(log, ticket);
xlog_ticket_put(log, ticket);
xfs_log_ticket_put(ticket);
} else {
xlog_trace_loggrant(log, ticket, "xfs_log_done: (permanent)");
xlog_regrant_reserve_log_space(log, ticket);
@ -514,7 +513,7 @@ xfs_log_reserve(xfs_mount_t *mp,
retval = xlog_regrant_write_log_space(log, internal_ticket);
} else {
/* may sleep if need to allocate more tickets */
internal_ticket = xlog_ticket_get(log, unit_bytes, cnt,
internal_ticket = xlog_ticket_alloc(log, unit_bytes, cnt,
client, flags);
if (!internal_ticket)
return XFS_ERROR(ENOMEM);
@ -749,7 +748,7 @@ xfs_log_unmount_write(xfs_mount_t *mp)
if (tic) {
xlog_trace_loggrant(log, tic, "unmount rec");
xlog_ungrant_log_space(log, tic);
xlog_ticket_put(log, tic);
xfs_log_ticket_put(tic);
}
} else {
/*
@ -3222,22 +3221,33 @@ xlog_state_want_sync(xlog_t *log, xlog_in_core_t *iclog)
*/
/*
* Free a used ticket.
* Free a used ticket when it's refcount falls to zero.
*/
STATIC void
xlog_ticket_put(xlog_t *log,
xlog_ticket_t *ticket)
void
xfs_log_ticket_put(
xlog_ticket_t *ticket)
{
sv_destroy(&ticket->t_wait);
kmem_zone_free(xfs_log_ticket_zone, ticket);
} /* xlog_ticket_put */
ASSERT(atomic_read(&ticket->t_ref) > 0);
if (atomic_dec_and_test(&ticket->t_ref)) {
sv_destroy(&ticket->t_wait);
kmem_zone_free(xfs_log_ticket_zone, ticket);
}
}
xlog_ticket_t *
xfs_log_ticket_get(
xlog_ticket_t *ticket)
{
ASSERT(atomic_read(&ticket->t_ref) > 0);
atomic_inc(&ticket->t_ref);
return ticket;
}
/*
* Allocate and initialise a new log ticket.
*/
STATIC xlog_ticket_t *
xlog_ticket_get(xlog_t *log,
xlog_ticket_alloc(xlog_t *log,
int unit_bytes,
int cnt,
char client,
@ -3308,6 +3318,7 @@ xlog_ticket_get(xlog_t *log,
unit_bytes += 2*BBSIZE;
}
atomic_set(&tic->t_ref, 1);
tic->t_unit_res = unit_bytes;
tic->t_curr_res = unit_bytes;
tic->t_cnt = cnt;
@ -3323,7 +3334,7 @@ xlog_ticket_get(xlog_t *log,
xlog_tic_reset_res(tic);
return tic;
} /* xlog_ticket_get */
}
/******************************************************************************

4
fs/xfs/xfs_log.h
View File

@ -134,6 +134,7 @@ typedef struct xfs_log_callback {
#ifdef __KERNEL__
/* Log manager interfaces */
struct xfs_mount;
struct xlog_ticket;
xfs_lsn_t xfs_log_done(struct xfs_mount *mp,
xfs_log_ticket_t ticket,
void **iclog,
@ -177,6 +178,9 @@ int xfs_log_need_covered(struct xfs_mount *mp);
void xlog_iodone(struct xfs_buf *);
struct xlog_ticket * xfs_log_ticket_get(struct xlog_ticket *ticket);
void xfs_log_ticket_put(struct xlog_ticket *ticket);
#endif

1
fs/xfs/xfs_log_priv.h
View File

@ -245,6 +245,7 @@ typedef struct xlog_ticket {
struct xlog_ticket *t_next; /* :4|8 */
struct xlog_ticket *t_prev; /* :4|8 */
xlog_tid_t t_tid; /* transaction identifier : 4 */
atomic_t t_ref; /* ticket reference count : 4 */
int t_curr_res; /* current reservation in bytes : 4 */
int t_unit_res; /* unit reservation in bytes : 4 */
char t_ocnt; /* original count : 1 */

9
fs/xfs/xfs_trans.c
View File

@ -290,7 +290,7 @@ xfs_trans_dup(
ASSERT(tp->t_ticket != NULL);
ntp->t_flags = XFS_TRANS_PERM_LOG_RES | (tp->t_flags & XFS_TRANS_RESERVE);
ntp->t_ticket = tp->t_ticket;
ntp->t_ticket = xfs_log_ticket_get(tp->t_ticket);
ntp->t_blk_res = tp->t_blk_res - tp->t_blk_res_used;
tp->t_blk_res = tp->t_blk_res_used;
ntp->t_rtx_res = tp->t_rtx_res - tp->t_rtx_res_used;
@ -1259,6 +1259,13 @@ xfs_trans_roll(
trans = *tpp;
/*
* transaction commit worked ok so we can drop the extra ticket
* reference that we gained in xfs_trans_dup()
*/
xfs_log_ticket_put(trans->t_ticket);
/*
* Reserve space in the log for th next transaction.
* This also pushes items in the "AIL", the list of logged items,

6
fs/xfs/xfs_utils.c
View File

@ -172,6 +172,12 @@ xfs_dir_ialloc(
*ipp = NULL;
return code;
}
/*
* transaction commit worked ok so we can drop the extra ticket
* reference that we gained in xfs_trans_dup()
*/
xfs_log_ticket_put(tp->t_ticket);
code = xfs_trans_reserve(tp, 0, log_res, 0,
XFS_TRANS_PERM_LOG_RES, log_count);
/*

6
fs/xfs/xfs_vnodeops.c
View File

@ -1018,6 +1018,12 @@ xfs_inactive_symlink_rmt(
ASSERT(XFS_FORCED_SHUTDOWN(mp));
goto error0;
}
/*
* transaction commit worked ok so we can drop the extra ticket
* reference that we gained in xfs_trans_dup()
*/
xfs_log_ticket_put(tp->t_ticket);
/*
* Remove the memory for extent descriptions (just bookkeeping).
*/