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xfs: remove callback dequeue loop from xlog_state_do_iclog_callbacks

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If we are processing callbacks on an iclog, nothing can be
concurrently adding callbacks to the loop. We only add callbacks to
the iclog when they are in ACTIVE or WANT_SYNC state, and we
explicitly do not add callbacks if the iclog is already in IOERROR
state.

The only way to have a dequeue racing with an enqueue is to be
processing a shutdown without a direct reference to an iclog in
ACTIVE or WANT_SYNC state. As the enqueue avoids this race
condition, we only ever need a single dequeue operation in
xlog_state_do_iclog_callbacks(). Hence we can remove the loop.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Dave Chinner 2021-06-25 11:21:01 -07:00 committed by Darrick J. Wong
parent 6be001021f
commit b6903358c2
1 changed files with 6 additions and 10 deletions
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16
fs/xfs/xfs_log.c
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@ -2774,19 +2774,15 @@ xlog_state_do_iclog_callbacks(
struct xlog *log,
struct xlog_in_core *iclog)
{
LIST_HEAD(tmp);
trace_xlog_iclog_callbacks_start(iclog, _RET_IP_);
spin_lock(&iclog->ic_callback_lock);
while (!list_empty(&iclog->ic_callbacks)) {
LIST_HEAD(tmp);
list_splice_init(&iclog->ic_callbacks, &tmp);
spin_unlock(&iclog->ic_callback_lock);
xlog_cil_process_committed(&tmp);
spin_lock(&iclog->ic_callback_lock);
}
list_splice_init(&iclog->ic_callbacks, &tmp);
spin_unlock(&iclog->ic_callback_lock);
xlog_cil_process_committed(&tmp);
trace_xlog_iclog_callbacks_done(iclog, _RET_IP_);
}