"Aneesh Kumar K. V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> writes:
> On Tue, 30 Mar 2010 18:24:35 +0400, Dmitry Monakhov <dmonakhov@xxxxxxxxxx> wrote:
>> allocated_meta_data is already included in 'used' variable.
>>
>> Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
>> ---
>> fs/ext4/inode.c | 3 ++-
>> 1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
>> index bec222c..bf989fb 100644
>> --- a/fs/ext4/inode.c
>> +++ b/fs/ext4/inode.c
>> @@ -1110,7 +1110,8 @@ void ext4_da_update_reserve_space(struct inode *inode,
>> */
>> if (allocated_meta_blocks)
>> dquot_claim_block(inode, allocated_meta_blocks);
>> - dquot_release_reservation_block(inode, mdb_free + used);
>> + dquot_release_reservation_block(inode, mdb_free + used -
>> + allocated_meta_blocks);
>> }
>>
>> /*
>
> Do we really need to do this ? IIUC reservation count and actual
> allocated count are two different. One block allocation we need to
> remove all the blocks reserved from the reservation count and add
Yes. remove all, but minus already allocated_metadata, which was
accounted in to metadata reservation.
> actually allocated blocks to the allocated count.
Just try an example:
reserve_space (inode, lblock := 1024 ) {
md_needed = ext4_calc_metadata_amount(inode, lblock) (let it be '2')
dquot_reserve_block(inode, md_needed + 1) /* '3' i.e blocks reserved*/
/* If this is first reservation for this inode then
dq_rsv = inode->i_reserved_data_blocks + inode->i_reserved_meta_block
*/
}
Later called from fallocate
update_rerved_space(inode, used:=1, claim :=0) {
/* Let i_allocatd_meta_data is '1' (as it so in most cases) */
ei->i_reserved_data_blocks -= used; /* 1 - 1 => 0 */
used += ei->i_allocated_meta_blocks; /* 1 + 1 => 2 */
ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks /* 2 - 1 => 1 */
allocated_meta_blocks = ei->i_allocated_meta_blocks; /* 1 */
ei->i_allocated_meta_blocks = 0;
if (ei->i_reserved_data_blocks == 0) /* True in our case */
mdb_free = ei->i_reserved_meta_blocks; /* mbd_free == 1*/
if (allocated_meta_blocks)
dquot_claim_block(inode, allocated_meta_blocks); /* claim '1' block*/
dquot_release_reservation_block(inode, mdb_free + used); /* free (1 + 2) */
/* So we reserved:
dq_rsv = i_reserved_data_blocks + i_reserved_meta_block ( 3 blocks)
But during update we claim + free:
i_allocated_meta_data+(i_reserved_data_block+i_reserved_meta_data)
(4 blocks).
Which result in incorrect dquota reservation accounting(it
goes negative)
*/
Initially i've found the issue by executing fsstress with falloc support.
It takes enouth process to catch writepage/fallocate overlapping.
xfstests-dev/ltp/xfsfsstress -p100 -n99999999
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