On 9/14/20 5:12 PM, Dave Chinner wrote:
> On Mon, Sep 14, 2020 at 01:26:01PM -0500, Eric Sandeen wrote:
>> When a too-small device is created with stripe geometry, we hit an
>> assert in align_ag_geometry():
>>
>> # truncate --size=10444800 testfile
>> # mkfs.xfs -dsu=65536,sw=1 testfile
>> mkfs.xfs: xfs_mkfs.c:2834: align_ag_geometry: Assertion `cfg->agcount != 0' failed.
>>
>> This is because align_ag_geometry() finds that the size of the last
>> (only) AG is too small, and attempts to trim it off. Obviously 0
>> AGs is invalid, and we hit the ASSERT.
>>
>> Fix this by skipping the last-ag-trim if there is only one AG, and
>> add a new test to validate_ag_geometry() which offers a very specific,
>> clear warning if the device (in dblocks) is smaller than the minimum
>> allowed AG size.
>>
>> Reported-by: Zdenek Kabelac <zkabelac@xxxxxxxxxx>
>> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
>> ---
>>
>> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
>> index a687f385..da8c5986 100644
>> --- a/mkfs/xfs_mkfs.c
>> +++ b/mkfs/xfs_mkfs.c
>> @@ -1038,6 +1038,15 @@ validate_ag_geometry(
>> uint64_t agsize,
>> uint64_t agcount)
>> {
>> + /* Is this device simply too small? */
>> + if (dblocks < XFS_AG_MIN_BLOCKS(blocklog)) {
>> + fprintf(stderr,
>> + _("device (%lld blocks) too small, need at least %lld blocks\n"),
>> + (long long)dblocks,
>> + (long long)XFS_AG_MIN_BLOCKS(blocklog));
>> + usage();
>> + }
>
> Ummm, shouldn't this be caught two checks later down by this:
>
> if (agsize > dblocks) {
> fprintf(stderr,
> _("agsize (%lld blocks) too big, data area is %lld blocks\n"),
> (long long)agsize, (long long)dblocks);
> usage();
> }
No, because we hit an ASSERT before we ever called this validation
function.
The error this is trying to fix is essentially: Do not attempt to
trim off the last/only AG in the filesystem.
-Eric
