Re: [PATCH v5 2/10] xfs: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate

From: Dave Chinner
Date: Sun Feb 23 2014 - 16:22:47 EST


On Wed, Feb 19, 2014 at 01:37:55AM +0900, Namjae Jeon wrote:
> From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
>
> This patch implements fallocate's FALLOC_FL_COLLAPSE_RANGE for XFS.
>
> The semantics of this flag are following:
> 1) It collapses the range lying between offset and length by removing any data
> blocks which are present in this range and than updates all the logical
> offsets of extents beyond "offset + len" to nullify the hole created by
> removing blocks. In short, it does not leave a hole.
> 2) It should be used exclusively. No other fallocate flag in combination.
> 3) Offset and length supplied to fallocate should be fs block size aligned
> in case of xfs and ext4.
> 4) Collaspe range does not work beyond i_size.
>
> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> Signed-off-by: Ashish Sangwan <a.sangwan@xxxxxxxxxxx>
.....
> + while (!error && !done) {
> + tp = xfs_trans_alloc(mp, XFS_TRANS_DIOSTRAT);
> + tp->t_flags |= XFS_TRANS_RESERVE;

This probably shouldn't use XFS_TRANS_RESERVE. If we are at ENOSPC,
then the operation simply fails. Yes, we've already punched the
hole, so we shouldn't get ENOSPC here, but I don't think it's worth
dipping into the reserve pool as it has much more important uses...

You don' tneed to resent the entire patch for this - I can remove it
directly myself....

Otherwise it looks good, so consider it

Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>

Cheers,

Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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