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authorDave Chinner <dchinner@redhat.com>2010-12-21 04:09:20 +0300
committerDave Chinner <david@fromorbit.com>2010-12-21 04:09:20 +0300
commit2ced19cbae5448b720919a494606c62095d4f4db (patch)
treee011a53041289ed4f9c8e78f6d88cd3454c9c39b /fs/xfs/xfs_log.c
parenteb40a87500ac2f6be7eaf8ebb35610e6d0e60e9a (diff)
downloadlinux-2ced19cbae5448b720919a494606c62095d4f4db.tar.xz
xfs: make AIL tail pushing independent of the grant lock
The xlog_grant_push_ail() currently takes the grant lock internally to sample the tail lsn, last sync lsn and the reserve grant head. Most of the callers already hold the grant lock but have to drop it before calling xlog_grant_push_ail(). This is a left over from when the AIL tail pushing was done in line and hence xlog_grant_push_ail had to drop the grant lock. AIL push is now done in another thread and hence we can safely hold the grant lock over the entire xlog_grant_push_ail call. Push the grant lock outside of xlog_grant_push_ail() to simplify the locking and synchronisation needed for tail pushing. This will reduce traffic on the grant lock by itself, but this is only one step in preparing for the complete removal of the grant lock. While there, clean up the formatting of xlog_grant_push_ail() to match the rest of the XFS code. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/xfs/xfs_log.c')
-rw-r--r--fs/xfs/xfs_log.c111
1 files changed, 54 insertions, 57 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index cc0504e0bb3b..1e2020d5a8b6 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -70,7 +70,7 @@ STATIC void xlog_state_want_sync(xlog_t *log, xlog_in_core_t *iclog);
/* local functions to manipulate grant head */
STATIC int xlog_grant_log_space(xlog_t *log,
xlog_ticket_t *xtic);
-STATIC void xlog_grant_push_ail(xfs_mount_t *mp,
+STATIC void xlog_grant_push_ail(struct log *log,
int need_bytes);
STATIC void xlog_regrant_reserve_log_space(xlog_t *log,
xlog_ticket_t *ticket);
@@ -318,7 +318,9 @@ xfs_log_reserve(
trace_xfs_log_reserve(log, internal_ticket);
- xlog_grant_push_ail(mp, internal_ticket->t_unit_res);
+ spin_lock(&log->l_grant_lock);
+ xlog_grant_push_ail(log, internal_ticket->t_unit_res);
+ spin_unlock(&log->l_grant_lock);
retval = xlog_regrant_write_log_space(log, internal_ticket);
} else {
/* may sleep if need to allocate more tickets */
@@ -332,9 +334,11 @@ xfs_log_reserve(
trace_xfs_log_reserve(log, internal_ticket);
- xlog_grant_push_ail(mp,
+ spin_lock(&log->l_grant_lock);
+ xlog_grant_push_ail(log,
(internal_ticket->t_unit_res *
internal_ticket->t_cnt));
+ spin_unlock(&log->l_grant_lock);
retval = xlog_grant_log_space(log, internal_ticket);
}
@@ -1185,59 +1189,58 @@ xlog_commit_record(
* water mark. In this manner, we would be creating a low water mark.
*/
STATIC void
-xlog_grant_push_ail(xfs_mount_t *mp,
- int need_bytes)
+xlog_grant_push_ail(
+ struct log *log,
+ int need_bytes)
{
- xlog_t *log = mp->m_log; /* pointer to the log */
- xfs_lsn_t tail_lsn; /* lsn of the log tail */
- xfs_lsn_t threshold_lsn = 0; /* lsn we'd like to be at */
- int free_blocks; /* free blocks left to write to */
- int free_bytes; /* free bytes left to write to */
- int threshold_block; /* block in lsn we'd like to be at */
- int threshold_cycle; /* lsn cycle we'd like to be at */
- int free_threshold;
-
- ASSERT(BTOBB(need_bytes) < log->l_logBBsize);
-
- spin_lock(&log->l_grant_lock);
- free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
- tail_lsn = log->l_tail_lsn;
- free_blocks = BTOBBT(free_bytes);
-
- /*
- * Set the threshold for the minimum number of free blocks in the
- * log to the maximum of what the caller needs, one quarter of the
- * log, and 256 blocks.
- */
- free_threshold = BTOBB(need_bytes);
- free_threshold = MAX(free_threshold, (log->l_logBBsize >> 2));
- free_threshold = MAX(free_threshold, 256);
- if (free_blocks < free_threshold) {
+ xfs_lsn_t threshold_lsn = 0;
+ xfs_lsn_t tail_lsn;
+ int free_blocks;
+ int free_bytes;
+ int threshold_block;
+ int threshold_cycle;
+ int free_threshold;
+
+ ASSERT(BTOBB(need_bytes) < log->l_logBBsize);
+
+ tail_lsn = log->l_tail_lsn;
+ free_bytes = xlog_space_left(log, &log->l_grant_reserve_head);
+ free_blocks = BTOBBT(free_bytes);
+
+ /*
+ * Set the threshold for the minimum number of free blocks in the
+ * log to the maximum of what the caller needs, one quarter of the
+ * log, and 256 blocks.
+ */
+ free_threshold = BTOBB(need_bytes);
+ free_threshold = MAX(free_threshold, (log->l_logBBsize >> 2));
+ free_threshold = MAX(free_threshold, 256);
+ if (free_blocks >= free_threshold)
+ return;
+
threshold_block = BLOCK_LSN(tail_lsn) + free_threshold;
threshold_cycle = CYCLE_LSN(tail_lsn);
if (threshold_block >= log->l_logBBsize) {
- threshold_block -= log->l_logBBsize;
- threshold_cycle += 1;
+ threshold_block -= log->l_logBBsize;
+ threshold_cycle += 1;
}
- threshold_lsn = xlog_assign_lsn(threshold_cycle, threshold_block);
-
- /* Don't pass in an lsn greater than the lsn of the last
+ threshold_lsn = xlog_assign_lsn(threshold_cycle,
+ threshold_block);
+ /*
+ * Don't pass in an lsn greater than the lsn of the last
* log record known to be on disk.
*/
if (XFS_LSN_CMP(threshold_lsn, log->l_last_sync_lsn) > 0)
- threshold_lsn = log->l_last_sync_lsn;
- }
- spin_unlock(&log->l_grant_lock);
-
- /*
- * Get the transaction layer to kick the dirty buffers out to
- * disk asynchronously. No point in trying to do this if
- * the filesystem is shutting down.
- */
- if (threshold_lsn &&
- !XLOG_FORCED_SHUTDOWN(log))
- xfs_trans_ail_push(log->l_ailp, threshold_lsn);
-} /* xlog_grant_push_ail */
+ threshold_lsn = log->l_last_sync_lsn;
+
+ /*
+ * Get the transaction layer to kick the dirty buffers out to
+ * disk asynchronously. No point in trying to do this if
+ * the filesystem is shutting down.
+ */
+ if (!XLOG_FORCED_SHUTDOWN(log))
+ xfs_trans_ail_push(log->l_ailp, threshold_lsn);
+}
/*
* The bdstrat callback function for log bufs. This gives us a central
@@ -2543,9 +2546,7 @@ redo:
trace_xfs_log_grant_sleep2(log, tic);
- spin_unlock(&log->l_grant_lock);
- xlog_grant_push_ail(log->l_mp, need_bytes);
- spin_lock(&log->l_grant_lock);
+ xlog_grant_push_ail(log, need_bytes);
XFS_STATS_INC(xs_sleep_logspace);
xlog_wait(&tic->t_wait, &log->l_grant_lock);
@@ -2641,9 +2642,7 @@ xlog_regrant_write_log_space(xlog_t *log,
trace_xfs_log_regrant_write_sleep1(log, tic);
- spin_unlock(&log->l_grant_lock);
- xlog_grant_push_ail(log->l_mp, need_bytes);
- spin_lock(&log->l_grant_lock);
+ xlog_grant_push_ail(log, need_bytes);
XFS_STATS_INC(xs_sleep_logspace);
xlog_wait(&tic->t_wait, &log->l_grant_lock);
@@ -2666,9 +2665,7 @@ redo:
if (free_bytes < need_bytes) {
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);
+ xlog_grant_push_ail(log, need_bytes);
XFS_STATS_INC(xs_sleep_logspace);
trace_xfs_log_regrant_write_sleep2(log, tic);