[PATCH 23/34] xfs: convert log grant ticket queues to list heads

Dave Chinner
2010-12-21T07:28:22Z

The grant write and reserve queues use a roll-your-own double linked
list, so convert it to a standard list_head structure and convert
all the list traversals to use list_for_each_entry(). We can also
get rid of the XLOG_TIC_IN_Q flag as we can use the list_empty()
check to tell if the ticket is in a list or not.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/linux-2.6/xfs_trace.h | 16 +++---
fs/xfs/xfs_log.c | 123 ++++++++++++++----------------------------
fs/xfs/xfs_log_priv.h | 11 ++---
3 files changed, 53 insertions(+), 97 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h
index 83e8760..69b9e1f 100644
--- a/fs/xfs/linux-2.6/xfs_trace.h
+++ b/fs/xfs/linux-2.6/xfs_trace.h
@@ -766,8 +766,8 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
__field(int, curr_res)
__field(int, unit_res)
__field(unsigned int, flags)
- __field(void *, reserve_headq)
- __field(void *, write_headq)
+ __field(int, reserveq)
+ __field(int, writeq)
__field(int, grant_reserve_cycle)
__field(int, grant_reserve_bytes)
__field(int, grant_write_cycle)
@@ -784,8 +784,8 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
__entry->curr_res = tic->t_curr_res;
__entry->unit_res = tic->t_unit_res;
__entry->flags = tic->t_flags;
- __entry->reserve_headq = log->l_reserve_headq;
- __entry->write_headq = log->l_write_headq;
+ __entry->reserveq = list_empty(&log->l_reserveq);
+ __entry->writeq = list_empty(&log->l_writeq);
__entry->grant_reserve_cycle = log->l_grant_reserve_cycle;
__entry->grant_reserve_bytes = log->l_grant_reserve_bytes;
__entry->grant_write_cycle = log->l_grant_write_cycle;
@@ -795,8 +795,8 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
__entry->tail_lsn = log->l_tail_lsn;
),
TP_printk("dev %d:%d type %s t_ocnt %u t_cnt %u t_curr_res %u "
- "t_unit_res %u t_flags %s reserve_headq 0x%p "
- "write_headq 0x%p grant_reserve_cycle %d "
+ "t_unit_res %u t_flags %s reserveq %s "
+ "writeq %s grant_reserve_cycle %d "
"grant_reserve_bytes %d grant_write_cycle %d "
"grant_write_bytes %d curr_cycle %d curr_block %d "
"tail_cycle %d tail_block %d",
@@ -807,8 +807,8 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
__entry->curr_res,
__entry->unit_res,
__print_flags(__entry->flags, "|", XLOG_TIC_FLAGS),
- __entry->reserve_headq,
- __entry->write_headq,
+ __entry->reserveq ? "empty" : "active",
+ __entry->writeq ? "empty" : "active",
__entry->grant_reserve_cycle,
__entry->grant_reserve_bytes,
__entry->grant_write_cycle,
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index cee4ab9..1b82735 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -95,38 +95,6 @@ STATIC void xlog_verify_tail_lsn(xlog_t *log, xlog_in_core_t *iclog,

STATIC int xlog_iclogs_empty(xlog_t *log);

-
-static void
-xlog_ins_ticketq(struct xlog_ticket **qp, struct xlog_ticket *tic)
-{
- if (*qp) {
- tic->t_next = (*qp);
- tic->t_prev = (*qp)->t_prev;
- (*qp)->t_prev->t_next = tic;
- (*qp)->t_prev = tic;
- } else {
- tic->t_prev = tic->t_next = tic;
- *qp = tic;
- }
-
- tic->t_flags |= XLOG_TIC_IN_Q;
-}
-
-static void
-xlog_del_ticketq(struct xlog_ticket **qp, struct xlog_ticket *tic)
-{
- if (tic == tic->t_next) {
- *qp = NULL;
- } else {
- *qp = tic->t_next;
- tic->t_next->t_prev = tic->t_prev;
- tic->t_prev->t_next = tic->t_next;
- }
-
- tic->t_next = tic->t_prev = NULL;
- tic->t_flags &= ~XLOG_TIC_IN_Q;
-}
-
static void
xlog_grant_sub_space(struct log *log, int bytes)
{
@@ -724,7 +692,7 @@ xfs_log_move_tail(xfs_mount_t *mp,
log->l_tail_lsn = tail_lsn;
}

- if ((tic = log->l_write_headq)) {
+ if (!list_empty(&log->l_writeq)) {
#ifdef DEBUG
if (log->l_flags & XLOG_ACTIVE_RECOVERY)
panic("Recovery problem");
@@ -732,7 +700,7 @@ xfs_log_move_tail(xfs_mount_t *mp,
cycle = log->l_grant_write_cycle;
bytes = log->l_grant_write_bytes;
free_bytes = xlog_space_left(log, cycle, bytes);
- do {
+ list_for_each_entry(tic, &log->l_writeq, t_queue) {
ASSERT(tic->t_flags & XLOG_TIC_PERM_RESERV);

if (free_bytes < tic->t_unit_res && tail_lsn != 1)
@@ -740,10 +708,10 @@ xfs_log_move_tail(xfs_mount_t *mp,
tail_lsn = 0;
free_bytes -= tic->t_unit_res;
sv_signal(&tic->t_wait);
- tic = tic->t_next;
- } while (tic != log->l_write_headq);
+ }
}
- if ((tic = log->l_reserve_headq)) {
+
+ if (!list_empty(&log->l_reserveq)) {
#ifdef DEBUG
if (log->l_flags & XLOG_ACTIVE_RECOVERY)
panic("Recovery problem");
@@ -751,7 +719,7 @@ xfs_log_move_tail(xfs_mount_t *mp,
cycle = log->l_grant_reserve_cycle;
bytes = log->l_grant_reserve_bytes;
free_bytes = xlog_space_left(log, cycle, bytes);
- do {
+ list_for_each_entry(tic, &log->l_reserveq, t_queue) {
if (tic->t_flags & XLOG_TIC_PERM_RESERV)
need_bytes = tic->t_unit_res*tic->t_cnt;
else
@@ -761,8 +729,7 @@ xfs_log_move_tail(xfs_mount_t *mp,
tail_lsn = 0;
free_bytes -= need_bytes;
sv_signal(&tic->t_wait);
- tic = tic->t_next;
- } while (tic != log->l_reserve_headq);
+ }
}
spin_unlock(&log->l_grant_lock);
} /* xfs_log_move_tail */
@@ -1053,6 +1020,8 @@ xlog_alloc_log(xfs_mount_t *mp,
log->l_curr_cycle = 1; /* 0 is bad since this is initial value */
log->l_grant_reserve_cycle = 1;
log->l_grant_write_cycle = 1;
+ INIT_LIST_HEAD(&log->l_reserveq);
+ INIT_LIST_HEAD(&log->l_writeq);

error = EFSCORRUPTED;
if (xfs_sb_version_hassector(&mp->m_sb)) {
@@ -2550,8 +2519,8 @@ xlog_grant_log_space(xlog_t *log,
trace_xfs_log_grant_enter(log, tic);

/* something is already sleeping; insert new transaction at end */
- if (log->l_reserve_headq) {
- xlog_ins_ticketq(&log->l_reserve_headq, tic);
+ if (!list_empty(&log->l_reserveq)) {
+ list_add_tail(&tic->t_queue, &log->l_reserveq);

trace_xfs_log_grant_sleep1(log, tic);

@@ -2583,8 +2552,8 @@ redo:
free_bytes = xlog_space_left(log, log->l_grant_reserve_cycle,
log->l_grant_reserve_bytes);
if (free_bytes < need_bytes) {
- if ((tic->t_flags & XLOG_TIC_IN_Q) == 0)
- xlog_ins_ticketq(&log->l_reserve_headq, tic);
+ if (list_empty(&tic->t_queue))
+ list_add_tail(&tic->t_queue, &log->l_reserveq);

trace_xfs_log_grant_sleep2(log, tic);

@@ -2602,8 +2571,9 @@ redo:
trace_xfs_log_grant_wake2(log, tic);

goto redo;
- } else if (tic->t_flags & XLOG_TIC_IN_Q)
- xlog_del_ticketq(&log->l_reserve_headq, tic);
+ }
+
+ list_del_init(&tic->t_queue);

/* we've got enough space */
xlog_grant_add_space(log, need_bytes);
@@ -2626,9 +2596,7 @@ redo:
return 0;

error_return:
- if (tic->t_flags & XLOG_TIC_IN_Q)
- xlog_del_ticketq(&log->l_reserve_headq, tic);
-
+ list_del_init(&tic->t_queue);
trace_xfs_log_grant_error(log, tic);

/*
@@ -2653,7 +2621,6 @@ xlog_regrant_write_log_space(xlog_t *log,
xlog_ticket_t *tic)
{
int free_bytes, need_bytes;
- xlog_ticket_t *ntic;
#ifdef DEBUG
xfs_lsn_t tail_lsn;
#endif
@@ -2683,22 +2650,23 @@ xlog_regrant_write_log_space(xlog_t *log,
* this transaction.
*/
need_bytes = tic->t_unit_res;
- if ((ntic = log->l_write_headq)) {
+ if (!list_empty(&log->l_writeq)) {
+ struct xlog_ticket *ntic;
free_bytes = xlog_space_left(log, log->l_grant_write_cycle,
log->l_grant_write_bytes);
- do {
+ list_for_each_entry(ntic, &log->l_writeq, t_queue) {
ASSERT(ntic->t_flags & XLOG_TIC_PERM_RESERV);

if (free_bytes < ntic->t_unit_res)
break;
free_bytes -= ntic->t_unit_res;
sv_signal(&ntic->t_wait);
- ntic = ntic->t_next;
- } while (ntic != log->l_write_headq);
+ }

- if (ntic != log->l_write_headq) {
- if ((tic->t_flags & XLOG_TIC_IN_Q) == 0)
- xlog_ins_ticketq(&log->l_write_headq, tic);
+ if (ntic != list_first_entry(&log->l_writeq,
+ struct xlog_ticket, t_queue)) {
+ if (list_empty(&tic->t_queue))
+ list_add_tail(&tic->t_queue, &log->l_writeq);

trace_xfs_log_regrant_write_sleep1(log, tic);

@@ -2727,8 +2695,8 @@ redo:
free_bytes = xlog_space_left(log, log->l_grant_write_cycle,
log->l_grant_write_bytes);
if (free_bytes < need_bytes) {
- if ((tic->t_flags & XLOG_TIC_IN_Q) == 0)
- xlog_ins_ticketq(&log->l_write_headq, tic);
+ if (list_empty(&tic->t_queue))
+ list_add_tail(&tic->t_queue, &log->l_writeq);
spin_unlock(&log->l_grant_lock);
xlog_grant_push_ail(log->l_mp, need_bytes);
spin_lock(&log->l_grant_lock);
@@ -2745,8 +2713,9 @@ redo:

trace_xfs_log_regrant_write_wake2(log, tic);
goto redo;
- } else if (tic->t_flags & XLOG_TIC_IN_Q)
- xlog_del_ticketq(&log->l_write_headq, tic);
+ }
+
+ list_del_init(&tic->t_queue);

/* we've got enough space */
xlog_grant_add_space_write(log, need_bytes);
@@ -2766,9 +2735,7 @@ redo:

error_return:
- if (tic->t_flags & XLOG_TIC_IN_Q)
- xlog_del_ticketq(&log->l_reserve_headq, tic);
-
+ list_del_init(&tic->t_queue);
trace_xfs_log_regrant_write_error(log, tic);

/*
@@ -3435,6 +3402,7 @@ xlog_ticket_alloc(
}

atomic_set(&tic->t_ref, 1);
+ INIT_LIST_HEAD(&tic->t_queue);
tic->t_unit_res = unit_bytes;
tic->t_curr_res = unit_bytes;
tic->t_cnt = cnt;
@@ -3742,26 +3710,17 @@ xfs_log_force_umount(
spin_unlock(&log->l_icloglock);

/*
- * We don't want anybody waiting for log reservations
- * after this. That means we have to wake up everybody
- * queued up on reserve_headq as well as write_headq.
- * In addition, we make sure in xlog_{re}grant_log_space
- * that we don't enqueue anything once the SHUTDOWN flag
- * is set, and this action is protected by the GRANTLOCK.
+ * We don't want anybody waiting for log reservations after this. That
+ * means we have to wake up everybody queued up on reserveq as well as
+ * writeq. In addition, we make sure in xlog_{re}grant_log_space that
+ * we don't enqueue anything once the SHUTDOWN flag is set, and this
+ * action is protected by the GRANTLOCK.
*/
- if ((tic = log->l_reserve_headq)) {
- do {
- sv_signal(&tic->t_wait);
- tic = tic->t_next;
- } while (tic != log->l_reserve_headq);
- }
+ list_for_each_entry(tic, &log->l_reserveq, t_queue)
+ sv_signal(&tic->t_wait);

- if ((tic = log->l_write_headq)) {
- do {
- sv_signal(&tic->t_wait);
- tic = tic->t_next;
- } while (tic != log->l_write_headq);
- }
+ list_for_each_entry(tic, &log->l_writeq, t_queue)
+ sv_signal(&tic->t_wait);
spin_unlock(&log->l_grant_lock);

if (!(log->l_iclog->ic_state & XLOG_STATE_IOERROR)) {
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index c1ce505..a5b3c02 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -132,12 +132,10 @@ static inline uint xlog_get_client_id(__be32 i)
*/
#define XLOG_TIC_INITED 0x1 /* has been initialized */
#define XLOG_TIC_PERM_RESERV 0x2 /* permanent reservation */
-#define XLOG_TIC_IN_Q 0x4

#define XLOG_TIC_FLAGS \
{ XLOG_TIC_INITED, "XLOG_TIC_INITED" }, \
- { XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" }, \
- { XLOG_TIC_IN_Q, "XLOG_TIC_IN_Q" }
+ { XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" }

#endif /* __KERNEL__ */

@@ -244,8 +242,7 @@ typedef struct xlog_res {

typedef struct xlog_ticket {
sv_t t_wait; /* ticket wait queue : 20 */
- struct xlog_ticket *t_next; /* :4|8 */
- struct xlog_ticket *t_prev; /* :4|8 */
+ struct list_head t_queue; /* reserve/write queue */
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 */
@@ -519,8 +516,8 @@ typedef struct log {

/* The following block of fields are changed while holding grant_lock */
spinlock_t l_grant_lock ____cacheline_aligned_in_smp;
- xlog_ticket_t *l_reserve_headq;
- xlog_ticket_t *l_write_headq;
+ struct list_head l_reserveq;
+ struct list_head l_writeq;
int l_grant_reserve_cycle;
int l_grant_reserve_bytes;
int l_grant_write_cycle;