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reduce l_icloglock roundtrips

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All but one caller of xlog_state_want_sync drop and re-acquire
l_icloglock around the call to it, just so that xlog_state_want_sync can
acquire and drop it.

Move all lock operation out of l_icloglock and assert that the lock is
held when it is called.

Note that it would make sense to extende this scheme to
xlog_state_release_iclog, but the locking in there is more complicated
and we'd like to keep the atomic_dec_and_lock optmization for those
callers not having l_icloglock yet.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
This commit is contained in:
Christoph Hellwig 2008-12-03 12:20:28 +01:00 committed by Niv Sardi
parent d9424b3c4a
commit 39e2defe73
1 changed files with 6 additions and 7 deletions
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13
fs/xfs/xfs_log.c
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@ -729,8 +729,8 @@ xfs_log_unmount_write(xfs_mount_t *mp)
spin_lock(&log->l_icloglock);
iclog = log->l_iclog;
atomic_inc(&iclog->ic_refcnt);
spin_unlock(&log->l_icloglock);
xlog_state_want_sync(log, iclog);
spin_unlock(&log->l_icloglock);
error = xlog_state_release_iclog(log, iclog);
spin_lock(&log->l_icloglock);
@ -767,9 +767,9 @@ xfs_log_unmount_write(xfs_mount_t *mp)
spin_lock(&log->l_icloglock);
iclog = log->l_iclog;
atomic_inc(&iclog->ic_refcnt);
spin_unlock(&log->l_icloglock);
xlog_state_want_sync(log, iclog);
spin_unlock(&log->l_icloglock);
error = xlog_state_release_iclog(log, iclog);
spin_lock(&log->l_icloglock);
@ -1984,7 +1984,9 @@ xlog_write(xfs_mount_t * mp,
if (iclog->ic_size - log_offset <= sizeof(xlog_op_header_t)) {
xlog_state_finish_copy(log, iclog, record_cnt, data_cnt);
record_cnt = data_cnt = 0;
spin_lock(&log->l_icloglock);
xlog_state_want_sync(log, iclog);
spin_unlock(&log->l_icloglock);
if (commit_iclog) {
ASSERT(flags & XLOG_COMMIT_TRANS);
*commit_iclog = iclog;
@ -3193,7 +3195,7 @@ try_again:
STATIC void
xlog_state_want_sync(xlog_t *log, xlog_in_core_t *iclog)
{
spin_lock(&log->l_icloglock);
ASSERT(spin_is_locked(&log->l_icloglock));
if (iclog->ic_state == XLOG_STATE_ACTIVE) {
xlog_state_switch_iclogs(log, iclog, 0);
@ -3201,10 +3203,7 @@ xlog_state_want_sync(xlog_t *log, xlog_in_core_t *iclog)
ASSERT(iclog->ic_state &
(XLOG_STATE_WANT_SYNC|XLOG_STATE_IOERROR));
}
spin_unlock(&log->l_icloglock);
} /* xlog_state_want_sync */
}
/*****************************************************************************