[PATCH 08/14] xfs: convert log grant heads to atomic variables

Dave Chinner
2010-11-29T01:37:33Z

From: Dave Chinner <dchinner@redhat.com>

Convert the log grant heads to atomic64_t types in preparation for
converting the accounting algorithms to atomic operations. his patch
just converts the variables; the algorithmic changes are in a
separate patch for clarity.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/linux-2.6/xfs_trace.h | 18 +++++++------
fs/xfs/xfs_log.c | 54 +++++++++++++++++++++--------------------
fs/xfs/xfs_log_priv.h | 4 +-
fs/xfs/xfs_log_recover.c | 8 +++---
4 files changed, 44 insertions(+), 40 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h
index d2cdc85..68c3bdd 100644
--- a/fs/xfs/linux-2.6/xfs_trace.h
+++ b/fs/xfs/linux-2.6/xfs_trace.h
@@ -768,8 +768,8 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
__field(unsigned int, flags)
__field(void *, reserveq)
__field(void *, writeq)
- __field(xfs_lsn_t, grant_reserve_lsn)
- __field(xfs_lsn_t, grant_write_lsn)
+ __field(xfs_lsn_t, grant_reserve_head)
+ __field(xfs_lsn_t, grant_write_head)
__field(int, curr_cycle)
__field(int, curr_block)
__field(xfs_lsn_t, tail_lsn)
@@ -784,8 +784,10 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
__entry->flags = tic->t_flags;
__entry->reserveq = log->l_reserveq.next;
__entry->writeq = log->l_writeq.next;
- __entry->grant_reserve_lsn = log->l_grant_reserve_lsn;
- __entry->grant_write_lsn = log->l_grant_write_lsn;
+ __entry->grant_reserve_head =
+ atomic64_read(&log->l_grant_reserve_head);
+ __entry->grant_write_head =
+ atomic64_read(&log->l_grant_write_head);
__entry->curr_cycle = log->l_curr_cycle;
__entry->curr_block = log->l_curr_block;
__entry->tail_lsn = atomic64_read(&log->l_tail_lsn);
@@ -805,10 +807,10 @@ DECLARE_EVENT_CLASS(xfs_loggrant_class,
__print_flags(__entry->flags, "|", XLOG_TIC_FLAGS),
__entry->reserveq,
__entry->writeq,
- CYCLE_LSN(__entry->grant_reserve_lsn),
- BLOCK_LSN(__entry->grant_reserve_lsn),
- CYCLE_LSN(__entry->grant_write_lsn),
- BLOCK_LSN(__entry->grant_write_lsn),
+ CYCLE_LSN(__entry->grant_reserve_head),
+ BLOCK_LSN(__entry->grant_reserve_head),
+ CYCLE_LSN(__entry->grant_write_head),
+ BLOCK_LSN(__entry->grant_write_head),
__entry->curr_cycle,
__entry->curr_block,
CYCLE_LSN(__entry->tail_lsn),
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 647f724..6298310 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -114,32 +114,34 @@ STATIC int xlog_iclogs_empty(xlog_t *log);
*/
static void
__xlog_grant_sub_space(
- xfs_lsn_t *head,
+ atomic64_t *head,
int bytes,
int logsize)
{
+ xfs_lsn_t head_lsn = atomic64_read(head);
int cycle, space;

- cycle = CYCLE_LSN(*head);
- space = BLOCK_LSN(*head);
+ cycle = CYCLE_LSN(head_lsn);
+ space = BLOCK_LSN(head_lsn);
space -= bytes;
if (space < 0) {
cycle--;
space += logsize;
}
- *head = xlog_assign_lsn(cycle, space);
+ atomic64_set(head, xlog_assign_lsn(cycle, space));
}

static void
__xlog_grant_add_space(
- xfs_lsn_t *head,
+ atomic64_t *head,
int bytes,
int logsize)
{
+ xfs_lsn_t head_lsn = atomic64_read(head);
int cycle, space, tmp;

- cycle = CYCLE_LSN(*head);
- space = BLOCK_LSN(*head);
+ cycle = CYCLE_LSN(head_lsn);
+ space = BLOCK_LSN(head_lsn);
tmp = logsize - space;
if (tmp > bytes)
space += bytes;
@@ -147,27 +149,27 @@ __xlog_grant_add_space(
cycle++;
space = bytes - tmp;
}
- *head = xlog_assign_lsn(cycle, space);
+ atomic64_set(head, xlog_assign_lsn(cycle, space));
}

static inline void
xlog_grant_sub_space(struct log *log, int bytes)
{
- __xlog_grant_sub_space(&log->l_grant_write_lsn, bytes, log->l_logsize);
- __xlog_grant_sub_space(&log->l_grant_reserve_lsn, bytes,
+ __xlog_grant_sub_space(&log->l_grant_write_head, bytes, log->l_logsize);
+ __xlog_grant_sub_space(&log->l_grant_reserve_head, bytes,
log->l_logsize);
}

static inline void
xlog_grant_add_space_write(struct log *log, int bytes)
{
- __xlog_grant_add_space(&log->l_grant_write_lsn, bytes, log->l_logsize);
+ __xlog_grant_add_space(&log->l_grant_write_head, bytes, log->l_logsize);
}

static void
xlog_grant_add_space_reserve(struct log *log, int bytes)
{
- __xlog_grant_add_space(&log->l_grant_reserve_lsn, bytes,
+ __xlog_grant_add_space(&log->l_grant_reserve_head, bytes,
log->l_logsize);
}

@@ -732,8 +734,8 @@ xfs_log_move_tail(xfs_mount_t *mp,
panic("Recovery problem");
#endif
free_bytes = xlog_space_left(log->l_logsize,
- atomic64_read(&log->l_tail_lsn),
- log->l_grant_write_lsn);
+ atomic64_read(&log->l_tail_lsn),
+ atomic64_read(&log->l_grant_write_head));
list_for_each_entry(tic, &log->l_writeq, t_queue) {
ASSERT(tic->t_flags & XLOG_TIC_PERM_RESERV);

@@ -751,8 +753,8 @@ xfs_log_move_tail(xfs_mount_t *mp,
panic("Recovery problem");
#endif
free_bytes = xlog_space_left(log->l_logsize,
- atomic64_read(&log->l_tail_lsn),
- log->l_grant_reserve_lsn);
+ atomic64_read(&log->l_tail_lsn),
+ atomic64_read(&log->l_grant_reserve_head));
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;
@@ -1050,8 +1052,8 @@ xlog_alloc_log(xfs_mount_t *mp,
log->l_curr_cycle = 1; /* 0 is bad since this is initial value */
atomic64_set(&log->l_tail_lsn, xlog_assign_lsn(1, 0));
atomic64_set(&log->l_last_sync_lsn, atomic64_read(&log->l_tail_lsn));
- log->l_grant_reserve_lsn = xlog_assign_lsn(1, 0);
- log->l_grant_write_lsn = xlog_assign_lsn(1, 0);
+ atomic64_set(&log->l_grant_reserve_head, xlog_assign_lsn(1, 0));
+ atomic64_set(&log->l_grant_write_head, xlog_assign_lsn(1, 0));
INIT_LIST_HEAD(&log->l_reserveq);
INIT_LIST_HEAD(&log->l_writeq);

@@ -1240,7 +1242,7 @@ xlog_grant_push_ail(
ASSERT(BTOBB(need_bytes) < log->l_logBBsize);

free_bytes = xlog_space_left(log->l_logsize, tail_lsn,
- log->l_grant_reserve_lsn);
+ atomic64_read(&log->l_grant_reserve_head));
free_blocks = BTOBBT(free_bytes);

/*
@@ -2552,8 +2554,8 @@ redo:
goto error_return;

free_bytes = xlog_space_left(log->l_logsize,
- atomic64_read(&log->l_tail_lsn),
- log->l_grant_reserve_lsn);
+ atomic64_read(&log->l_tail_lsn),
+ atomic64_read(&log->l_grant_reserve_head));
/*
* If there is not enough space or there is queued waiter and we
* are not already on the queue, we need to wait.
@@ -2641,8 +2643,8 @@ redo:
goto error_return;

free_bytes = xlog_space_left(log->l_logsize,
- atomic64_read(&log->l_tail_lsn),
- log->l_grant_write_lsn);
+ atomic64_read(&log->l_tail_lsn),
+ atomic64_read(&log->l_grant_write_head));
/*
* If there is not enough space or there is queued waiter and we
* are not already on the queue, we need to wait.
@@ -3422,8 +3424,8 @@ xlog_verify_grant_head(
struct log *log,
int equals)
{
- xfs_lsn_t reserve = log->l_grant_reserve_lsn;
- xfs_lsn_t write = log->l_grant_write_lsn;
+ xfs_lsn_t reserve = atomic64_read(&log->l_grant_reserve_head);
+ xfs_lsn_t write = atomic64_read(&log->l_grant_write_head);

if (CYCLE_LSN(reserve) == CYCLE_LSN(write)) {
if (equals)
@@ -3441,7 +3443,7 @@ xlog_verify_grant_tail(
struct log *log)
{
xfs_lsn_t tail_lsn = atomic64_read(&log->l_tail_lsn);
- xfs_lsn_t write_lsn = log->l_grant_write_lsn;
+ xfs_lsn_t write_lsn = atomic64_read(&log->l_grant_write_head);

/*
* Check to make sure the grant write head didn't just over lap the
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 667d8cb..971dc8a 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -516,8 +516,8 @@ typedef struct log {
spinlock_t l_grant_lock ____cacheline_aligned_in_smp;
struct list_head l_reserveq;
struct list_head l_writeq;
- xfs_lsn_t l_grant_reserve_lsn;
- xfs_lsn_t l_grant_write_lsn;
+ atomic64_t l_grant_reserve_head;
+ atomic64_t l_grant_write_head;

/*
* l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index c6285fd..6e7dfbb 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -927,10 +927,10 @@ xlog_find_tail(
log->l_curr_cycle++;
atomic64_set(&log->l_tail_lsn, be64_to_cpu(rhead->h_tail_lsn));
atomic64_set(&log->l_last_sync_lsn, be64_to_cpu(rhead->h_lsn));
- log->l_grant_reserve_lsn = xlog_assign_lsn(log->l_curr_cycle,
- BBTOB(log->l_curr_block));
- log->l_grant_write_lsn = xlog_assign_lsn(log->l_curr_cycle,
- BBTOB(log->l_curr_block));
+ atomic64_set(&log->l_grant_reserve_head,
+ xlog_assign_lsn(log->l_curr_cycle, BBTOB(log->l_curr_block)));
+ atomic64_set(&log->l_grant_write_head,
+ xlog_assign_lsn(log->l_curr_cycle, BBTOB(log->l_curr_block)));

/*
* Look for unmount record. If we find it, then we know there
--
1.7.2.3