xfs
[Top] [All Lists]

Re: [PATCH 4/4] xfs: obey minleft values during extent allocation correc

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 4/4] xfs: obey minleft values during extent allocation correctly.
From: Lachlan McIlroy <lmcilroy@xxxxxxxxxx>
Date: Thu, 21 Apr 2011 01:05:18 -0400 (EDT)
Cc: xfs@xxxxxxxxxxx
In-reply-to: <1303360144-10632-5-git-send-email-david@xxxxxxxxxxxxx>
Reply-to: Lachlan McIlroy <lmcilroy@xxxxxxxxxx>
----- Original Message -----
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> When allocating an extent that is long enough to consume the
> remaining free space in an AG, we need to ensure that the allocation
> leaves enough space in the AG for any subsequent bmap btree blocks
> that are needed to track the new extent. These have to be allocated
> in the same AG as we only reserve enough blocks in an allocation
> transaction for modification of the freespace trees in a single AG.
> 
> xfs_alloc_fix_minleft() has been considering blocks on the AGFL as
> free blocks available for extent and bmbt block allocation, which is
> not correct - blocks on the AGFL are there exclusively for the use
> of the free space btrees. As a result, when minleft is less than the
> number of blocks on the AGFL, xfs_alloc_fix_minleft() does not trim
> the given extent to leave minleft blocks available for bmbt
> allocation, and hence we can fail allocation during bmbt record
> insertion.
> 
> A further problem is that bmbt block allocation doesn't set the
> total number of blocks correctly for the allocation, thereby
> allowing it to allocate a block from the AGFL before failing on the
> second block in xfs_alloc_fix_freelist(). The total needs to be set
> so that it skips AGs that only have the minimum reserved
> amount of AGFL blocks free in them.
> 
> Similarly, xfs_inobt_alloc_block() needs to set args->total as well.

Dave, you seem to have dropped the args->total changes?

> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
> fs/xfs/xfs_alloc.c | 1 -
> 1 files changed, 0 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
> index 27d64d7..8946464 100644
> --- a/fs/xfs/xfs_alloc.c
> +++ b/fs/xfs/xfs_alloc.c
> @@ -280,7 +280,6 @@ xfs_alloc_fix_minleft(
> return 1;
> agf = XFS_BUF_TO_AGF(args->agbp);
> diff = be32_to_cpu(agf->agf_freeblks)
> - + be32_to_cpu(agf->agf_flcount)
> - args->len - args->minleft;
> if (diff >= 0)
> return 1;
> --
> 1.7.4.4
> 
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs

<Prev in Thread] Current Thread [Next in Thread>