2.6.37-stable review patch. If anyone has any objections, please let us know.
------------------ From: NeilBrown <[email protected]> commit 0ca69886a8273ac1350143d562280bfcbe4760dc upstream. 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. Signed-off-by: NeilBrown <[email protected]> Reported-by: "Hawrylewicz Czarnowski, Przemyslaw" <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/md/md.c | 8 ++++++-- drivers/md/md.h | 3 ++- 2 files changed, 8 insertions(+), 3 deletions(-) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -288,10 +288,12 @@ static int md_make_request(struct reques 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; --- 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; _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
