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Re: [PATCH v5 04/11] xfs: update inode allocation/free transaction reser

To: Brian Foster <bfoster@xxxxxxxxxx>
Subject: Re: [PATCH v5 04/11] xfs: update inode allocation/free transaction reservations for finobt
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Thu, 24 Apr 2014 15:32:59 +1000
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1397146116-42546-5-git-send-email-bfoster@xxxxxxxxxx>
References: <1397146116-42546-1-git-send-email-bfoster@xxxxxxxxxx> <1397146116-42546-5-git-send-email-bfoster@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, Apr 10, 2014 at 12:08:29PM -0400, Brian Foster wrote:
> Create the xfs_calc_finobt_res() helper to calculate the finobt log
> reservation for inode allocation and free. Update
> XFS_IALLOC_SPACE_RES() to reserve blocks for the additional finobt
> insertion on inode allocation. Create XFS_IFREE_SPACE_RES() to
> reserve blocks for the potential finobt record insertion on inode
> free (i.e., if an inode chunk was previously fully allocated).
> 
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
> ---
>  fs/xfs/xfs_inode.c       | 25 ++++++++++++++++++++++-
>  fs/xfs/xfs_trans_resv.c  | 53 
> +++++++++++++++++++++++++++++++++++++++++++++---
>  fs/xfs/xfs_trans_space.h |  7 ++++++-
>  3 files changed, 80 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 5e7a38f..8576892 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -1837,8 +1837,31 @@ xfs_inactive_ifree(
>       int                     error;
>  
>       tp = xfs_trans_alloc(mp, XFS_TRANS_INACTIVE);
> -     error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ifree, 0, 0);
> +
> +     /*
> +      * The ifree transaction might need to allocate blocks for record
> +      * insertion to the finobt. We don't want to fail here at ENOSPC, so
> +      * allow ifree to dip into the reserved block pool if necessary.
> +      *
> +      * Freeing large sets of inodes generally means freeing inode chunks,
> +      * directory and file data blocks, so this should be relatively safe.
> +      * Only under severe circumstances should it be possible to free enough
> +      * inodes to exhaust the reserve block pool via finobt expansion while
> +      * at the same time not creating free space in the filesystem.
> +      *
> +      * Send a warning if the reservation does happen to fail, as the inode
> +      * now remains allocated and sits on the unlinked list until the fs is
> +      * repaired.
> +      */
> +     tp->t_flags |= XFS_TRANS_RESERVE;
> +     error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ifree,
> +                               XFS_IFREE_SPACE_RES(mp), 0);
>       if (error) {
> +             if (error == ENOSPC)
> +                     xfs_warn_ratelimited(mp,
> +                     "Failed to remove inode(s) from unlinked list. "
> +                     "Please free space, unmount and run xfs_repair.");
> +
>               ASSERT(XFS_FORCED_SHUTDOWN(mp));
>               xfs_trans_cancel(tp, XFS_TRANS_RELEASE_LOG_RES);
>               return error;

Comment is good, but if we get an ENOSPC error here we won't be in a
shutdown state, hence the assert needs fixing (i.e. else {assert})

Otherwise this looks good.

Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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