diff options
author | NeilBrown <neilb@suse.de> | 2008-07-21 17:05:25 +1000 |
---|---|---|
committer | NeilBrown <neilb@suse.de> | 2008-07-21 17:05:25 +1000 |
commit | 4b80991c6cb9efa607bc4fd6f3ecdf5511c31bb0 (patch) | |
tree | 5e2ba7d509af245c29bdf04b00960cc367972c44 /drivers/md/bitmap.c | |
parent | f2ea68cf42aafdd93393b6b8b20fc3c2b5f4390c (diff) |
md: Protect access to mddev->disks list using RCU
All modifications and most access to the mddev->disks list are made
under the reconfig_mutex lock. However there are three places where
the list is walked without any locking. If a reconfig happens at this
time, havoc (and oops) can ensue.
So use RCU to protect these accesses:
- wrap them in rcu_read_{,un}lock()
- use list_for_each_entry_rcu
- add to the list with list_add_rcu
- delete from the list with list_del_rcu
- delay the 'free' with call_rcu rather than schedule_work
Note that export_rdev did a list_del_init on this list. In almost all
cases the entry was not in the list anymore so it was a no-op and so
safe. It is no longer safe as after list_del_rcu we may not touch
the list_head.
An audit shows that export_rdev is called:
- after unbind_rdev_from_array, in which case the delete has
already been done,
- after bind_rdev_to_array fails, in which case the delete isn't needed.
- before the device has been put on a list at all (e.g. in
add_new_disk where reading the superblock fails).
- and in autorun devices after a failure when the device is on a
different list.
So remove the list_del_init call from export_rdev, and add it back
immediately before the called to export_rdev for that last case.
Note also that ->same_set is sometimes used for lists other than
mddev->list (e.g. candidates). In these cases rcu is not needed.
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md/bitmap.c')
-rw-r--r-- | drivers/md/bitmap.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index eba83e25b678..621a272a2c74 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -241,10 +241,10 @@ static struct page *read_sb_page(mddev_t *mddev, long offset, unsigned long inde static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait) { mdk_rdev_t *rdev; - struct list_head *tmp; mddev_t *mddev = bitmap->mddev; - rdev_for_each(rdev, tmp, mddev) + rcu_read_lock(); + rdev_for_each_rcu(rdev, mddev) if (test_bit(In_sync, &rdev->flags) && !test_bit(Faulty, &rdev->flags)) { int size = PAGE_SIZE; @@ -260,11 +260,11 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait) + (long)(page->index * (PAGE_SIZE/512)) + size/512 > 0) /* bitmap runs in to metadata */ - return -EINVAL; + goto bad_alignment; if (rdev->data_offset + mddev->size*2 > rdev->sb_start + bitmap->offset) /* data runs in to bitmap */ - return -EINVAL; + goto bad_alignment; } else if (rdev->sb_start < rdev->data_offset) { /* METADATA BITMAP DATA */ if (rdev->sb_start @@ -272,7 +272,7 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait) + page->index*(PAGE_SIZE/512) + size/512 > rdev->data_offset) /* bitmap runs in to data */ - return -EINVAL; + goto bad_alignment; } else { /* DATA METADATA BITMAP - no problems */ } @@ -282,10 +282,15 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait) size, page); } + rcu_read_unlock(); if (wait) md_super_wait(mddev); return 0; + + bad_alignment: + rcu_read_unlock(); + return -EINVAL; } static void bitmap_file_kick(struct bitmap *bitmap); |