diff options
| author | Qu Wenruo <wqu@suse.com> | 2022-10-21 08:43:45 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2022-10-25 10:17:33 +0200 |
| commit | 76a66ba101329316a5d7f4275070be22eb85fdf2 (patch) | |
| tree | f39c9d1c6db7d74c9f3c89f927fc955437a986f1 /fs | |
| parent | 2398091f9c2c8e0040f4f9928666787a3e8108a7 (diff) | |
btrfs: don't use btrfs_chunk::sub_stripes from disk
[BUG]
There are two reports (the earliest one from LKP, a more recent one from
kernel bugzilla) that we can have some chunks with 0 as sub_stripes.
This will cause divide-by-zero errors at btrfs_rmap_block, which is
introduced by a recent kernel patch ac0677348f3c ("btrfs: merge
calculations for simple striped profiles in btrfs_rmap_block"):
if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
BTRFS_BLOCK_GROUP_RAID10)) {
stripe_nr = stripe_nr * map->num_stripes + i;
stripe_nr = div_u64(stripe_nr, map->sub_stripes); <<<
}
[CAUSE]
From the more recent report, it has been proven that we have some chunks
with 0 as sub_stripes, mostly caused by older mkfs.
It turns out that the mkfs.btrfs fix is only introduced in 6718ab4d33aa
("btrfs-progs: Initialize sub_stripes to 1 in btrfs_alloc_data_chunk")
which is included in v5.4 btrfs-progs release.
So there would be quite some old filesystems with such 0 sub_stripes.
[FIX]
Just don't trust the sub_stripes values from disk.
We have a trusted btrfs_raid_array[] to fetch the correct sub_stripes
numbers for each profile and that are fixed.
By this, we can keep the compatibility with older filesystems while
still avoid divide-by-zero bugs.
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Viktor Kuzmin <kvaster@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216559
Fixes: ac0677348f3c ("btrfs: merge calculations for simple striped profiles in btrfs_rmap_block")
CC: stable@vger.kernel.org # 6.0
Reviewed-by: Su Yue <glass@fydeos.io>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/volumes.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 94ba46d57920..a8d4bc6a1937 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -7142,6 +7142,7 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf, u64 devid; u64 type; u8 uuid[BTRFS_UUID_SIZE]; + int index; int num_stripes; int ret; int i; @@ -7149,6 +7150,7 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf, logical = key->offset; length = btrfs_chunk_length(leaf, chunk); type = btrfs_chunk_type(leaf, chunk); + index = btrfs_bg_flags_to_raid_index(type); num_stripes = btrfs_chunk_num_stripes(leaf, chunk); #if BITS_PER_LONG == 32 @@ -7202,7 +7204,15 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf, map->io_align = btrfs_chunk_io_align(leaf, chunk); map->stripe_len = btrfs_chunk_stripe_len(leaf, chunk); map->type = type; - map->sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk); + /* + * We can't use the sub_stripes value, as for profiles other than + * RAID10, they may have 0 as sub_stripes for filesystems created by + * older mkfs (<v5.4). + * In that case, it can cause divide-by-zero errors later. + * Since currently sub_stripes is fixed for each profile, let's + * use the trusted value instead. + */ + map->sub_stripes = btrfs_raid_array[index].sub_stripes; map->verified_stripes = 0; em->orig_block_len = btrfs_calc_stripe_length(em); for (i = 0; i < num_stripes; i++) { |