[RFC v5 PATCH 1/9] xfs: set t_task at wait time instead of alloc time

[Brian Foster <bfoster@redhat.com>]

The xlog_ticket structure contains a task reference to support
blocking for available log reservation. This reference is assigned
at ticket allocation time, which assumes that the transaction
allocator will acquire reservation in the same context. This is
normally true, but will not always be the case with automatic
relogging.

There is otherwise no fundamental reason log space cannot be
reserved for a ticket from a context different from the allocating
context. Move the task assignment to the log reservation blocking
code where it is used.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/xfs_log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index f6006d94a581..df60942a9804 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -262,6 +262,7 @@ xlog_grant_head_wait(
 	int			need_bytes) __releases(&head->lock)
 					    __acquires(&head->lock)
 {
+	tic->t_task = current;
 	list_add_tail(&tic->t_queue, &head->waiters);
 
 	do {
@@ -3601,7 +3602,6 @@ xlog_ticket_alloc(
 	unit_res = xfs_log_calc_unit_res(log->l_mp, unit_bytes);
 
 	atomic_set(&tic->t_ref, 1);
-	tic->t_task		= current;
 	INIT_LIST_HEAD(&tic->t_queue);
 	tic->t_unit_res		= unit_res;
 	tic->t_curr_res		= unit_res;
-- 
2.21.1