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 51d82290ad4c6d25ef2c52d599e3f88f6c96e934..aeea3b7f3d5e0128c8b39c74c329ae906d9fe1e8 100644 (file)
--- 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 @@ static struct selector *alloc_selector(void)
        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 @@ static int ql_add_path(struct path_selector *ps, struct dm_path *path,
        struct path_info *pi;
        unsigned repeat_count = QL_MIN_IO;
        char dummy;
+       unsigned long flags;
 
        /*
         * Arguments: [<repeat_count>]
@@ -147,7 +150,9 @@ static int ql_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;
 }
@@ -156,16 +161,22 @@ static void ql_fail_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(&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 @@ static struct dm_path *ql_select_path(struct path_selector *ps,
 {
        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 @@ static struct dm_path *ql_select_path(struct path_selector *ps,
        }
 
        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,

diff --git a/drivers/md/dm-round-robin.c b/drivers/md/dm-round-robin.c
index 65ffdc3403b6ce963eb89b6cf3fe09aeb88d734f..be9aa7f30b61aedc3b3ab41ae48dbe4ffd4838c2 100644 (file)
--- a/drivers/md/dm-round-robin.c
+++ b/drivers/md/dm-round-robin.c
@@ -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;
 }

diff --git a/drivers/md/dm-service-time.c b/drivers/md/dm-service-time.c
index 0370eaf3d94910959b71495f2e4e0796bf58792c..d09bcbe3655dca59aa5d83b15253531f9818dbb2 100644 (file)
--- a/drivers/md/dm-service-time.c
+++ b/drivers/md/dm-service-time.c
@@ -24,6 +24,7 @@
 struct selector {
        struct list_head valid_paths;
        struct list_head failed_paths;
+       spinlock_t lock;
 };
 
 struct path_info {
@@ -41,6 +42,7 @@ static struct selector *alloc_selector(void)
        if (s) {
                INIT_LIST_HEAD(&s->valid_paths);
                INIT_LIST_HEAD(&s->failed_paths);
+               spin_lock_init(&s->lock);
        }
 
        return s;
@@ -111,6 +113,7 @@ static int st_add_path(struct path_selector *ps, struct dm_path *path,
        unsigned repeat_count = ST_MIN_IO;
        unsigned relative_throughput = 1;
        char dummy;
+       unsigned long flags;
 
        /*
         * Arguments: [<repeat_count> [<relative_throughput>]]
@@ -160,7 +163,9 @@ static int st_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;
 }
@@ -169,16 +174,22 @@ static void st_fail_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(&pi->list, &s->failed_paths);
+       spin_unlock_irqrestore(&s->lock, flags);
 }
 
 static int st_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;
 }
@@ -265,9 +276,12 @@ static struct dm_path *st_select_path(struct path_selector *ps,
 {
        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);
@@ -277,11 +291,14 @@ static struct dm_path *st_select_path(struct path_selector *ps,
                        best = pi;
 
        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 st_start_io(struct path_selector *ps, struct dm_path *path,