On 8/2/18 1:02 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Prior to the arrival of copy on write, i_delayed_blks tracked the number
> of blocks that had been reserved for delayed allocations. Though the
> counter was 32-bits in size, this was enough because writeback would
> generally start flushing files well before we hit 2^32 blocks of dirty
> data.
>
> However, now that we're using it to track CoW reservations as well, it's
> possible to create so many of those reservations that we overflow the
> counter. This is kind of an extreme case (it requires ~16T of COW
> reservations) but we ought to avoid this trivial overflow. A userspace
> visible effect is that stat i_blocks returns incorrect values.
>
> Change the field to xfs_filblks_t, which should suffice to fix the
> problem. There already was a 4-byte hole in struct xfs_inode, so we get
> this for free.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
I think delblks in xfs_qm_vop_chown_reserve() needs to be bumped up
too then, no?
(and, uh, does it then need to be chased through
xfs_trans_reserve_quota_bydquot, xfs_trans_dqresv etc?)
-Eric
> ---
> fs/xfs/xfs_inode.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index 59b06133ceb8..3fd0e07a363e 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -48,7 +48,7 @@ typedef struct xfs_inode {
> spinlock_t i_flags_lock; /* inode i_flags lock */
> /* Miscellaneous state. */
> unsigned long i_flags; /* see defined flags below */
> - unsigned int i_delayed_blks; /* count of delay alloc blks */
> + xfs_filblks_t i_delayed_blks; /* count of delay alloc blks */
>
> struct xfs_icdinode i_d; /* most of ondisk inode */
>
> --
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