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btrfs: zoned: bail out in btrfs_alloc_chunk for bad input 

gcc complains that the ctl->max_chunk_size member might be used
uninitialized when none of the three conditions for initializing it in
init_alloc_chunk_ctl_policy_zoned() are true:

In function ‘init_alloc_chunk_ctl_policy_zoned’,
    inlined from ‘init_alloc_chunk_ctl’ at fs/btrfs/volumes.c:5023:3,
    inlined from ‘btrfs_alloc_chunk’ at fs/btrfs/volumes.c:5340:2:
include/linux/compiler-gcc.h:48:45: error: ‘ctl.max_chunk_size’ may be used uninitialized [-Werror=maybe-uninitialized]
 4998 |         ctl->max_chunk_size = min(limit, ctl->max_chunk_size);
      |                               ^~~
fs/btrfs/volumes.c: In function ‘btrfs_alloc_chunk’:
fs/btrfs/volumes.c:5316:32: note: ‘ctl’ declared here
 5316 |         struct alloc_chunk_ctl ctl;
      |                                ^~~

If we ever get into this condition, something is seriously
wrong, as validity is checked in the callers

  btrfs_alloc_chunk
    init_alloc_chunk_ctl
      init_alloc_chunk_ctl_policy_zoned

so the same logic as in init_alloc_chunk_ctl_policy_regular()
and a few other places should be applied. This avoids both further
data corruption, and the compile-time warning.

Fixes: 1cd6121f2a ("btrfs: zoned: implement zoned chunk allocator")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Arnd Bergmann 2021-03-23 15:31:19 +01:00 committed by David Sterba
parent 3227788cd3
commit bb05b298af
1 changed files with 2 additions and 0 deletions
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2
fs/btrfs/volumes.c
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@ -4989,6 +4989,8 @@ static void init_alloc_chunk_ctl_policy_zoned(
ctl->max_chunk_size = 2 * ctl->max_stripe_size;
ctl->devs_max = min_t(int, ctl->devs_max,
BTRFS_MAX_DEVS_SYS_CHUNK);
} else {
BUG();
}
/* We don't want a chunk larger than 10% of writable space */