[PATCH] md: provide proper rcu_dereference / rcu_assign_pointer annotations in md

Acked-by: <paulmck@us.ibm.com>
Signed-off-by: Suzanne Wood <suzannew@cs.pdx.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 14 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index bbe40e9cf923..26114f40bde6 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -496,6 +496,7 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio)
         int disk, slot, nslot;
         const int sectors = r10_bio->sectors;
         sector_t new_distance, current_distance;
+        mdk_rdev_t *rdev;
 
         raid10_find_phys(conf, r10_bio);
         rcu_read_lock();
@@ -510,8 +511,8 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio)
                 slot = 0;
                 disk = r10_bio->devs[slot].devnum;
 
-                while (!conf->mirrors[disk].rdev ||
-                       !conf->mirrors[disk].rdev->in_sync) {
+                while ((rdev = rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
+                       !rdev->in_sync) {
                         slot++;
                         if (slot == conf->copies) {
                                 slot = 0;
@@ -527,8 +528,8 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio)
         /* make sure the disk is operational */
         slot = 0;
         disk = r10_bio->devs[slot].devnum;
-        while (!conf->mirrors[disk].rdev ||
-               !conf->mirrors[disk].rdev->in_sync) {
+        while ((rdev=rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
+               !rdev->in_sync) {
                 slot ++;
                 if (slot == conf->copies) {
                         disk = -1;
@@ -547,11 +548,11 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio)
                 int ndisk = r10_bio->devs[nslot].devnum;
 
 
-                if (!conf->mirrors[ndisk].rdev ||
-                    !conf->mirrors[ndisk].rdev->in_sync)
+                if ((rdev=rcu_dereference(conf->mirrors[ndisk].rdev)) == NULL ||
+                    !rdev->in_sync)
                         continue;
 
-                if (!atomic_read(&conf->mirrors[ndisk].rdev->nr_pending)) {
+                if (!atomic_read(&rdev->nr_pending)) {
                         disk = ndisk;
                         slot = nslot;
                         break;
@@ -569,7 +570,7 @@ rb_out:
         r10_bio->read_slot = slot;
 /*      conf->next_seq_sect = this_sector + sectors;*/
 
-        if (disk >= 0 && conf->mirrors[disk].rdev)
+        if (disk >= 0 && (rdev=rcu_dereference(conf->mirrors[disk].rdev))!= NULL)
                 atomic_inc(&conf->mirrors[disk].rdev->nr_pending);
         rcu_read_unlock();
 
@@ -583,7 +584,7 @@ static void unplug_slaves(mddev_t *mddev)
 
         rcu_read_lock();
         for (i=0; i<mddev->raid_disks; i++) {
-                mdk_rdev_t *rdev = conf->mirrors[i].rdev;
+                mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
                 if (rdev && !rdev->faulty && atomic_read(&rdev->nr_pending)) {
                         request_queue_t *r_queue = bdev_get_queue(rdev->bdev);
 
@@ -614,7 +615,7 @@ static int raid10_issue_flush(request_queue_t *q, struct gendisk *disk,
 
         rcu_read_lock();
         for (i=0; i<mddev->raid_disks && ret == 0; i++) {
-                mdk_rdev_t *rdev = conf->mirrors[i].rdev;
+                mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
                 if (rdev && !rdev->faulty) {
                         struct block_device *bdev = rdev->bdev;
                         request_queue_t *r_queue = bdev_get_queue(bdev);
@@ -768,9 +769,10 @@ static int make_request(request_queue_t *q, struct bio * bio)
         rcu_read_lock();
         for (i = 0;  i < conf->copies; i++) {
                 int d = r10_bio->devs[i].devnum;
-                if (conf->mirrors[d].rdev &&
-                    !conf->mirrors[d].rdev->faulty) {
-                        atomic_inc(&conf->mirrors[d].rdev->nr_pending);
+                mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
+                if (rdev &&
+                    !rdev->faulty) {
+                        atomic_inc(&rdev->nr_pending);
                         r10_bio->devs[i].bio = bio;
                 } else
                         r10_bio->devs[i].bio = NULL;
@@ -980,7 +982,7 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
                         p->head_position = 0;
                         rdev->raid_disk = mirror;
                         found = 1;
-                        p->rdev = rdev;
+                        rcu_assign_pointer(p->rdev, rdev);
                         break;
                 }