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| author | Mikulas Patocka <mpatocka@redhat.com> | 2009-12-11 00:51:54 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2009-12-11 00:51:54 +0100 |
| commit | 8e87b9b81b3c370f7e53c1ab6e1c3519ef37a644 (patch) | |
| tree | 272a8532e12749c6c8419dcab0c341604646c571 /drivers/md | |
| parent | dm snapshot: only take lock for statustype info not table (diff) | |
| download | linux-8e87b9b81b3c370f7e53c1ab6e1c3519ef37a644.tar.xz linux-8e87b9b81b3c370f7e53c1ab6e1c3519ef37a644.zip | |
dm snapshot: cope with chunk size larger than origin
Under some special conditions the snapshot hash_size is calculated as zero.
This patch instead sets a minimum value of 64, the same as for the
pending exception table.
rounddown_pow_of_two(0) is an undefined operation (it expands to shift
by -1). init_exception_table with an argument of 0 would fail with -ENOMEM.
The way to trigger the problem is to create a snapshot with a chunk size
that is larger than the origin device.
Cc: stable@kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-snap.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index d135212958f1..8a4a9c838afd 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -553,6 +553,8 @@ static int init_hash_tables(struct dm_snapshot *s) hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; hash_size = min(hash_size, max_buckets); + if (hash_size < 64) + hash_size = 64; hash_size = rounddown_pow_of_two(hash_size); if (init_exception_table(&s->complete, hash_size, DM_CHUNK_CONSECUTIVE_BITS)) |