[PATCH] device-mapper multipath: Fix pg initialisation races
Prevent more than one priority group initialisation function from being
outstanding at once. Otherwise the completion functions interfere with each
other. Also, reloading the table could reference a freed pointer.
Only reset queue_io in pg_init_complete if another pg_init isn't required.
Skip process_queued_ios if the queue is empty so that we only trigger a
pg_init if there's I/O.
Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 98da8ee..785806b 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -63,6 +63,7 @@
unsigned nr_priority_groups;
struct list_head priority_groups;
unsigned pg_init_required; /* pg_init needs calling? */
+ unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
unsigned nr_valid_paths; /* Total number of usable paths */
struct pgpath *current_pgpath;
@@ -308,7 +309,8 @@
/* Queue for the daemon to resubmit */
bio_list_add(&m->queued_ios, bio);
m->queue_size++;
- if (m->pg_init_required || !m->queue_io)
+ if ((m->pg_init_required && !m->pg_init_in_progress) ||
+ !m->queue_io)
queue_work(kmultipathd, &m->process_queued_ios);
pgpath = NULL;
r = 0;
@@ -335,7 +337,7 @@
m->saved_queue_if_no_path = m->queue_if_no_path;
m->queue_if_no_path = queue_if_no_path;
- if (!m->queue_if_no_path)
+ if (!m->queue_if_no_path && m->queue_size)
queue_work(kmultipathd, &m->process_queued_ios);
spin_unlock_irqrestore(&m->lock, flags);
@@ -380,25 +382,31 @@
{
struct multipath *m = (struct multipath *) data;
struct hw_handler *hwh = &m->hw_handler;
- struct pgpath *pgpath;
- unsigned init_required, must_queue = 0;
+ struct pgpath *pgpath = NULL;
+ unsigned init_required = 0, must_queue = 1;
unsigned long flags;
spin_lock_irqsave(&m->lock, flags);
+ if (!m->queue_size)
+ goto out;
+
if (!m->current_pgpath)
__choose_pgpath(m);
pgpath = m->current_pgpath;
- if ((pgpath && m->queue_io) ||
- (!pgpath && m->queue_if_no_path))
- must_queue = 1;
+ if ((pgpath && !m->queue_io) ||
+ (!pgpath && !m->queue_if_no_path))
+ must_queue = 0;
- init_required = m->pg_init_required;
- if (init_required)
+ if (m->pg_init_required && !m->pg_init_in_progress) {
m->pg_init_required = 0;
+ m->pg_init_in_progress = 1;
+ init_required = 1;
+ }
+out:
spin_unlock_irqrestore(&m->lock, flags);
if (init_required)
@@ -843,7 +851,7 @@
pgpath->path.is_active = 1;
m->current_pgpath = NULL;
- if (!m->nr_valid_paths++)
+ if (!m->nr_valid_paths++ && m->queue_size)
queue_work(kmultipathd, &m->process_queued_ios);
queue_work(kmultipathd, &m->trigger_event);
@@ -969,12 +977,13 @@
bypass_pg(m, pg, 1);
spin_lock_irqsave(&m->lock, flags);
- if (!err_flags)
- m->queue_io = 0;
- else {
+ if (err_flags) {
m->current_pgpath = NULL;
m->current_pg = NULL;
- }
+ } else if (!m->pg_init_required)
+ m->queue_io = 0;
+
+ m->pg_init_in_progress = 0;
queue_work(kmultipathd, &m->process_queued_ios);
spin_unlock_irqrestore(&m->lock, flags);
}