From 0ca69886a8273ac1350143d562280bfcbe4760dc Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 14 Jan 2011 09:14:33 +1100 Subject: [PATCH] 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: Signed-off-by: NeilBrown Reported-by: "Hawrylewicz Czarnowski, Przemyslaw" --- drivers/md/md.c | 8 ++++++-- drivers/md/md.h | 3 ++- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index a301912..540347c 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 d05bab5..229675a 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; -- 2.7.4