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authorDave Chinner <dchinner@redhat.com>2010-12-21 12:28:39 +1100
committerDave Chinner <david@fromorbit.com>2010-12-21 12:28:39 +1100
commit1c3cb9ec07fabf0c0970adc46fd2a1f09c1186dd (patch)
treeb8b6bf968f663723b06aa68ec499e49f3cdfbad0 /fs/xfs/xfs_log_recover.c
parent84f3c683c4d3f36d3c3ed320babd960a332ac458 (diff)
xfs: convert l_tail_lsn to an atomic variable.
log->l_tail_lsn is currently protected by the log grant lock. The lock is only needed for serialising readers against writers, so we don't really need the lock if we make the l_tail_lsn variable an atomic. Converting the l_tail_lsn variable to an atomic64_t means we can start to peel back the grant lock from various operations. Also, provide functions to safely crack an atomic LSN variable into it's component pieces and to recombined the components into an atomic variable. Use them where appropriate. This also removes the need for explicitly holding a spinlock to read the l_tail_lsn on 32 bit platforms. Signed-off-by: Dave Chinner <dchinner@redhat.com>
Diffstat (limited to 'fs/xfs/xfs_log_recover.c')
-rw-r--r--fs/xfs/xfs_log_recover.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 18e1e18d714..204d8e5fa7f 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -936,7 +936,7 @@ xlog_find_tail(
log->l_curr_cycle = be32_to_cpu(rhead->h_cycle);
if (found == 2)
log->l_curr_cycle++;
- log->l_tail_lsn = be64_to_cpu(rhead->h_tail_lsn);
+ 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));
xlog_assign_grant_head(&log->l_grant_reserve_head, log->l_curr_cycle,
BBTOB(log->l_curr_block));
@@ -971,7 +971,7 @@ xlog_find_tail(
}
after_umount_blk = (i + hblks + (int)
BTOBB(be32_to_cpu(rhead->h_len))) % log->l_logBBsize;
- tail_lsn = log->l_tail_lsn;
+ tail_lsn = atomic64_read(&log->l_tail_lsn);
if (*head_blk == after_umount_blk &&
be32_to_cpu(rhead->h_num_logops) == 1) {
umount_data_blk = (i + hblks) % log->l_logBBsize;
@@ -986,12 +986,10 @@ xlog_find_tail(
* log records will point recovery to after the
* current unmount record.
*/
- log->l_tail_lsn =
- xlog_assign_lsn(log->l_curr_cycle,
- after_umount_blk);
- atomic64_set(&log->l_last_sync_lsn,
- xlog_assign_lsn(log->l_curr_cycle,
- after_umount_blk));
+ xlog_assign_atomic_lsn(&log->l_tail_lsn,
+ log->l_curr_cycle, after_umount_blk);
+ xlog_assign_atomic_lsn(&log->l_last_sync_lsn,
+ log->l_curr_cycle, after_umount_blk);
*tail_blk = after_umount_blk;
/*