diff options
| author | NeilBrown <neilb@suse.de> | 2014-12-15 12:56:56 +1100 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2015-02-04 08:35:52 +1100 |
| commit | 5c675f83c68fbdf9c0e103c1090b06be747fa62c (patch) | |
| tree | 9a03f84c7a3bcef7d5e757dc28ce7bd5d205b26a /drivers/md/raid10.c | |
| parent | 85572d7c75fd5b9fa3fc911e1c99c68ec74903a0 (diff) | |
md: make ->congested robust against personality changes.
There is currently no locking around calls to the 'congested'
bdi function. If called at an awkward time while an array is
being converted from one level (or personality) to another, there
is a tiny chance of running code in an unreferenced module etc.
So add a 'congested' function to the md_personality operations
structure, and call it with appropriate locking from a central
'mddev_congested'.
When the array personality is changing the array will be 'suspended'
so no IO is processed.
If mddev_congested detects this, it simply reports that the
array is congested, which is a safe guess.
As mddev_suspend calls synchronize_rcu(), mddev_congested can
avoid races by included the whole call inside an rcu_read_lock()
region.
This require that the congested functions for all subordinate devices
can be run under rcu_lock. Fortunately this is the case.
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md/raid10.c')
| -rw-r--r-- | drivers/md/raid10.c | 14 |
1 files changed, 2 insertions, 12 deletions
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 32e282f4c83c..fb6b88674e87 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -910,7 +910,7 @@ retry: return rdev; } -int md_raid10_congested(struct mddev *mddev, int bits) +static int raid10_congested(struct mddev *mddev, int bits) { struct r10conf *conf = mddev->private; int i, ret = 0; @@ -934,15 +934,6 @@ int md_raid10_congested(struct mddev *mddev, int bits) rcu_read_unlock(); return ret; } -EXPORT_SYMBOL_GPL(md_raid10_congested); - -static int raid10_congested(void *data, int bits) -{ - struct mddev *mddev = data; - - return mddev_congested(mddev, bits) || - md_raid10_congested(mddev, bits); -} static void flush_pending_writes(struct r10conf *conf) { @@ -3757,8 +3748,6 @@ static int run(struct mddev *mddev) if (mddev->queue) { int stripe = conf->geo.raid_disks * ((mddev->chunk_sectors << 9) / PAGE_SIZE); - mddev->queue->backing_dev_info.congested_fn = raid10_congested; - mddev->queue->backing_dev_info.congested_data = mddev; /* Calculate max read-ahead size. * We need to readahead at least twice a whole stripe.... @@ -4727,6 +4716,7 @@ static struct md_personality raid10_personality = .check_reshape = raid10_check_reshape, .start_reshape = raid10_start_reshape, .finish_reshape = raid10_finish_reshape, + .congested = raid10_congested, }; static int __init raid_init(void) |