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dm mpath: push path selector locking down to path selectors

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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>
This commit is contained in:
Mike Snitzer
2016-02-15 14:25:00 -05:00
parent 21136f89d7
commit 9659f81144
3 changed files with 59 additions and 11 deletions
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24
drivers/md/dm-round-robin.c
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@@ -46,6 +46,7 @@ static void free_paths(struct list_head *paths)
struct selector {
struct list_head valid_paths;
struct list_head invalid_paths;
spinlock_t lock;
};
static struct selector *alloc_selector(void)
@@ -55,6 +56,7 @@ static struct selector *alloc_selector(void)
if (s) {
INIT_LIST_HEAD(&s->valid_paths);
INIT_LIST_HEAD(&s->invalid_paths);
spin_lock_init(&s->lock);
}
return s;
@@ -74,7 +76,7 @@ static int rr_create(struct path_selector *ps, unsigned argc, char **argv)
static void rr_destroy(struct path_selector *ps)
{
struct selector *s = (struct selector *) ps->context;
struct selector *s = ps->context;
free_paths(&s->valid_paths);
free_paths(&s->invalid_paths);
@@ -111,10 +113,11 @@ static int rr_status(struct path_selector *ps, struct dm_path *path,
static int rr_add_path(struct path_selector *ps, struct dm_path *path,
int argc, char **argv, char **error)
{
struct selector *s = (struct selector *) ps->context;
struct selector *s = ps->context;
struct path_info *pi;
unsigned repeat_count = RR_MIN_IO;
char dummy;
unsigned long flags;
if (argc > 1) {
*error = "round-robin ps: incorrect number of arguments";
@@ -144,25 +147,33 @@ static int rr_add_path(struct path_selector *ps, struct dm_path *path,
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;
}
static void rr_fail_path(struct path_selector *ps, struct dm_path *p)
{
struct selector *s = (struct selector *) ps->context;
unsigned long flags;
struct selector *s = ps->context;
struct path_info *pi = p->pscontext;
spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->invalid_paths);
spin_unlock_irqrestore(&s->lock, flags);
}
static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
{
struct selector *s = (struct selector *) ps->context;
unsigned long flags;
struct selector *s = ps->context;
struct path_info *pi = p->pscontext;
spin_lock_irqsave(&s->lock, flags);
list_move(&pi->list, &s->valid_paths);
spin_unlock_irqrestore(&s->lock, flags);
return 0;
}
@@ -170,14 +181,17 @@ static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
static struct dm_path *rr_select_path(struct path_selector *ps,
unsigned *repeat_count, size_t nr_bytes)
{
struct selector *s = (struct selector *) ps->context;
unsigned long flags;
struct selector *s = ps->context;
struct path_info *pi = NULL;
spin_lock_irqsave(&s->lock, flags);
if (!list_empty(&s->valid_paths)) {
pi = list_entry(s->valid_paths.next, struct path_info, list);
list_move_tail(&pi->list, &s->valid_paths);
*repeat_count = pi->repeat_count;
}
spin_unlock_irqrestore(&s->lock, flags);
return pi ? pi->path : NULL;
}