From 27d8d5fe0ef9daeaafbdd32b14b32a2211930062 Mon Sep 17 00:00:00 2001 From: David Chinner Date: Thu, 30 Oct 2008 17:38:39 +1100 Subject: [XFS] Use a cursor for AIL traversal. To replace the current generation number ensuring sanity of the AIL traversal, replace it with an external cursor that is linked to the AIL. Basically, we store the next item in the cursor whenever we want to drop the AIL lock to do something to the current item. When we regain the lock. the current item may already be free, so we can't reference it, but the next item in the traversal is already held in the cursor. When we move or delete an object, we search all the active cursors and if there is an item match we clear the cursor(s) that point to the object. This forces the traversal to restart transparently. We don't invalidate the cursor on insert because the cursor still points to a valid item. If the intem is inserted between the current item and the cursor it does not matter; the traversal is considered to be past the insertion point so it will be picked up in the next traversal. Hence traversal restarts pretty much disappear altogether with this method of traversal, which should substantially reduce the overhead of pushing on a busy AIL. Version 2 o add restart logic o comment cursor interface o minor cleanups SGI-PV: 988143 SGI-Modid: xfs-linux-melb:xfs-kern:32347a Signed-off-by: David Chinner Signed-off-by: Lachlan McIlroy Signed-off-by: Christoph Hellwig --- fs/xfs/xfs_log.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/xfs/xfs_log.c') diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 0b02c6443551..4184085d44af 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -900,7 +900,7 @@ xfs_log_move_tail(xfs_mount_t *mp, int xfs_log_need_covered(xfs_mount_t *mp) { - int needed = 0, gen; + int needed = 0; xlog_t *log = mp->m_log; if (!xfs_fs_writable(mp)) @@ -909,7 +909,7 @@ xfs_log_need_covered(xfs_mount_t *mp) spin_lock(&log->l_icloglock); if (((log->l_covered_state == XLOG_STATE_COVER_NEED) || (log->l_covered_state == XLOG_STATE_COVER_NEED2)) - && !xfs_trans_first_ail(mp, &gen) + && !xfs_trans_first_ail(mp, NULL) && xlog_iclogs_empty(log)) { if (log->l_covered_state == XLOG_STATE_COVER_NEED) log->l_covered_state = XLOG_STATE_COVER_DONE; -- cgit v1.2.1