dm mpath: push path selector locking down to path selectors
Proper locking of the lists used by the path selectors should be handled
within the selectors (relying on dm-mpath.c code's use of the m->lock
spinlock was reckless).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-queue-length.c b/drivers/md/dm-queue-length.c
index 51d8229..aeea3b7 100644
--- a/drivers/md/dm-queue-length.c
+++ b/drivers/md/dm-queue-length.c
@@ -29,6 +29,7 @@
struct selector {
struct list_head valid_paths;
struct list_head failed_paths;
+ spinlock_t lock;
};
struct path_info {
@@ -45,6 +46,7 @@
if (s) {
INIT_LIST_HEAD(&s->valid_paths);
INIT_LIST_HEAD(&s->failed_paths);
+ spin_lock_init(&s->lock);
}
return s;
@@ -113,6 +115,7 @@
struct path_info *pi;
unsigned repeat_count = QL_MIN_IO;
char dummy;
+ unsigned long flags;
/*
* Arguments: [<repeat_count>]
@@ -147,7 +150,9 @@
path->pscontext = pi;
+ spin_lock_irqsave(&s->lock, flags);
list_add_tail(&pi->list, &s->valid_paths);
+ spin_unlock_irqrestore(&s->lock, flags);
return 0;
}
@@ -156,16 +161,22 @@
{
struct selector *s = ps->context;
struct path_info *pi = path->pscontext;
+ unsigned long flags;
+ spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->failed_paths);
+ spin_unlock_irqrestore(&s->lock, flags);
}
static int ql_reinstate_path(struct path_selector *ps, struct dm_path *path)
{
struct selector *s = ps->context;
struct path_info *pi = path->pscontext;
+ unsigned long flags;
+ spin_lock_irqsave(&s->lock, flags);
list_move_tail(&pi->list, &s->valid_paths);
+ spin_unlock_irqrestore(&s->lock, flags);
return 0;
}
@@ -178,9 +189,12 @@
{
struct selector *s = ps->context;
struct path_info *pi = NULL, *best = NULL;
+ struct dm_path *ret = NULL;
+ unsigned long flags;
+ spin_lock_irqsave(&s->lock, flags);
if (list_empty(&s->valid_paths))
- return NULL;
+ goto out;
/* Change preferred (first in list) path to evenly balance. */
list_move_tail(s->valid_paths.next, &s->valid_paths);
@@ -195,11 +209,14 @@
}
if (!best)
- return NULL;
+ goto out;
*repeat_count = best->repeat_count;
- return best->path;
+ ret = best->path;
+out:
+ spin_unlock_irqrestore(&s->lock, flags);
+ return ret;
}
static int ql_start_io(struct path_selector *ps, struct dm_path *path,
