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authorNeilBrown <neilb@suse.de>2011-01-14 09:14:33 +1100
committerNeilBrown <neilb@suse.de>2011-01-14 09:14:33 +1100
commit0ca69886a8273ac1350143d562280bfcbe4760dc (patch)
tree98acbe1e5682e4455bf7d2e7a9413b5a3fd43b2a /drivers
parent067032bc628598606056412594042564fcf09e22 (diff)
md: Ensure no IO request to get md device before it is properly initialised.
When an md device is in the process of coming on line it is possible for an IO request (typically a partition table probe) to get through before the array is fully initialised, which can cause unexpected behaviour (e.g. a crash). So explicitly record when the array is ready for IO and don't allow IO through until then. There is no possibility for a similar problem when the array is going off-line as there must only be one 'open' at that time, and it is busy off-lining the array and so cannot send IO requests. So no memory barrier is needed in md_stop() This has been a bug since commit 409c57f3801 in 2.6.30 which introduced md_make_request. Before then, each personality would register its own make_request_fn when it was ready. This is suitable for any stable kernel from 2.6.30.y onwards. Cc: <stable@kernel.org> Signed-off-by: NeilBrown <neilb@suse.de> Reported-by: "Hawrylewicz Czarnowski, Przemyslaw" <przemyslaw.hawrylewicz.czarnowski@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/md.c8
-rw-r--r--drivers/md/md.h3
2 files changed, 8 insertions, 3 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index a3019121dc57..540347c538f9 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -288,10 +288,12 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
int rv;
int cpu;
- if (mddev == NULL || mddev->pers == NULL) {
+ if (mddev == NULL || mddev->pers == NULL
+ || !mddev->ready) {
bio_io_error(bio);
return 0;
}
+ smp_rmb(); /* Ensure implications of 'active' are visible */
rcu_read_lock();
if (mddev->suspended) {
DEFINE_WAIT(__wait);
@@ -4564,7 +4566,8 @@ int md_run(mddev_t *mddev)
mddev->safemode_timer.data = (unsigned long) mddev;
mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
mddev->in_sync = 1;
-
+ smp_wmb();
+ mddev->ready = 1;
list_for_each_entry(rdev, &mddev->disks, same_set)
if (rdev->raid_disk >= 0) {
char nm[20];
@@ -4725,6 +4728,7 @@ EXPORT_SYMBOL_GPL(md_stop_writes);
void md_stop(mddev_t *mddev)
{
+ mddev->ready = 0;
mddev->pers->stop(mddev);
if (mddev->pers->sync_request && mddev->to_remove == NULL)
mddev->to_remove = &md_redundancy_group;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index d05bab55df4e..229675a604f7 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -148,7 +148,8 @@ struct mddev_s
* are happening, so run/
* takeover/stop are not safe
*/
-
+ int ready; /* See when safe to pass
+ * IO requests down */
struct gendisk *gendisk;
struct kobject kobj;