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author | Christoph Hellwig <hch@infradead.org> | 2012-04-23 15:58:33 +1000 |
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committer | Ben Myers <bpm@sgi.com> | 2012-05-14 16:20:26 -0500 |
commit | 1c30462542bac8abffb4823638b6b1659c1cfcf5 (patch) | |
tree | b86f1fc14eb0f41e224833128ecc81163227d044 /fs/xfs/xfs_log.c | |
parent | 32ce90a4b79155a155de2b284d8b69023e5e8fea (diff) | |
download | linux-stable-1c30462542bac8abffb4823638b6b1659c1cfcf5.tar.gz linux-stable-1c30462542bac8abffb4823638b6b1659c1cfcf5.tar.bz2 linux-stable-1c30462542bac8abffb4823638b6b1659c1cfcf5.zip |
xfs: allow assigning the tail lsn with the AIL lock held
Provide a variant of xlog_assign_tail_lsn that has the AIL lock already
held. By doing so we do an additional atomic_read + atomic_set under
the lock, which comes down to two instructions.
Switch xfs_trans_ail_update_bulk and xfs_trans_ail_delete_bulk to the
new version to reduce the number of lock roundtrips, and prepare for
a new addition that would require a third lock roundtrip in
xfs_trans_ail_delete_bulk. This addition is also the reason for
slightly rearranging the conditionals and relying on xfs_log_space_wake
for checking that the filesystem has been shut down internally.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_log.c')
-rw-r--r-- | fs/xfs/xfs_log.c | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 6db1fef38bff..418d5d7bc52b 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -916,27 +916,42 @@ xfs_log_need_covered(xfs_mount_t *mp) * We may be holding the log iclog lock upon entering this routine. */ xfs_lsn_t -xlog_assign_tail_lsn( +xlog_assign_tail_lsn_locked( struct xfs_mount *mp) { - xfs_lsn_t tail_lsn; struct log *log = mp->m_log; + struct xfs_log_item *lip; + xfs_lsn_t tail_lsn; + + assert_spin_locked(&mp->m_ail->xa_lock); /* * To make sure we always have a valid LSN for the log tail we keep * track of the last LSN which was committed in log->l_last_sync_lsn, - * and use that when the AIL was empty and xfs_ail_min_lsn returns 0. - * - * If the AIL has been emptied we also need to wake any process - * waiting for this condition. + * and use that when the AIL was empty. */ - tail_lsn = xfs_ail_min_lsn(mp->m_ail); - if (!tail_lsn) + lip = xfs_ail_min(mp->m_ail); + if (lip) + tail_lsn = lip->li_lsn; + else tail_lsn = atomic64_read(&log->l_last_sync_lsn); atomic64_set(&log->l_tail_lsn, tail_lsn); return tail_lsn; } +xfs_lsn_t +xlog_assign_tail_lsn( + struct xfs_mount *mp) +{ + xfs_lsn_t tail_lsn; + + spin_lock(&mp->m_ail->xa_lock); + tail_lsn = xlog_assign_tail_lsn_locked(mp); + spin_unlock(&mp->m_ail->xa_lock); + + return tail_lsn; +} + /* * Return the space in the log between the tail and the head. The head * is passed in the cycle/bytes formal parms. In the special case where |