From e71bf0d0ee89e51b92776391c5634938236977d5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 3 Sep 2008 09:03:02 +0200 Subject: block: fix disk->part[] dereferencing race disk->part[] is protected by its matching bdev's lock. However, non-critical accesses like collecting stats and printing out sysfs and proc information used to be performed without any locking. As partitions can come and go dynamically, partitions can go away underneath those non-critical accesses. As some of those accesses are writes, this theoretically can lead to silent corruption. This patch fixes the race by using RCU for the partition array and dev reference counter to hold partitions. * Rename disk->part[] to disk->__part[] to make sure no one outside genhd layer proper accesses it directly. * Use RCU for disk->__part[] dereferencing. * Implement disk_{get|put}_part() which can be used to get and put partitions from gendisk respectively. * Iterators are implemented to help iterate through all partitions safely. * Functions which require RCU readlock are marked with _rcu suffix. * Use disk_put_part() in __blkdev_put() instead of directly putting the contained kobject. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- drivers/block/aoe/aoecmd.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c index 885d1409521..84c03d65dcc 100644 --- a/drivers/block/aoe/aoecmd.c +++ b/drivers/block/aoe/aoecmd.c @@ -757,11 +757,15 @@ diskstats(struct gendisk *disk, struct bio *bio, ulong duration, sector_t sector const int rw = bio_data_dir(bio); struct hd_struct *part; - part = disk_map_sector(disk, sector); + rcu_read_lock(); + + part = disk_map_sector_rcu(disk, sector); all_stat_inc(disk, part, ios[rw], sector); all_stat_add(disk, part, ticks[rw], duration, sector); all_stat_add(disk, part, sectors[rw], n_sect, sector); all_stat_add(disk, part, io_ticks, duration, sector); + + rcu_read_unlock(); } void -- cgit v1.2.3-18-g5258