From: Brian Foster <bfoster@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 06/10] xfs: fix bmap minleft calculation
Date: Mon, 17 Apr 2017 10:19:39 -0400 [thread overview]
Message-ID: <20170417141939.GD41659@bfoster.bfoster> (raw)
In-Reply-To: <20170413080517.12564-7-hch@lst.de>
On Thu, Apr 13, 2017 at 10:05:13AM +0200, Christoph Hellwig wrote:
> We need to set a proper minleft value even if we didn't do a previous
> allocation in the transaction, as we can't switch to a different AG
> after allocating the data extent.
>
Hmm, the code currently does set minleft if we haven't done a previous
allocation (firstblock == NULLFSBLOCK). Do you mean "even if we have
done a previous allocation?"
The code seems Ok, but we also currently reserve enough blocks for a
full btree split in a write transaction and afaict only allocate a
single extent per-transaction. The current code expects to select an AG
with those additional blocks available and then not if a subsequent
allocation occurs (by setting minleft = 0), presumably because the check
was already made. So I'm wondering if this fixes a problem that has been
observed or is just cleaning up the code..?
Brian
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/xfs/libxfs/xfs_bmap.c | 27 +++++++++++++++++----------
> fs/xfs/libxfs/xfs_bmap.h | 1 -
> 2 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 53f1386b1868..6faefa342748 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -3570,6 +3570,22 @@ xfs_bmap_btalloc_filestreams(
> return 0;
> }
>
> +/*
> + * Return the minimum number of blocks required for the bmap btree manipulation
> + * after adding a single extent.
> + */
> +static xfs_extlen_t
> +xfs_bmap_minleft(
> + struct xfs_bmalloca *ap)
> +{
> + int whichfork = xfs_bmapi_whichfork(ap->flags);
> + struct xfs_ifork *ifp = XFS_IFORK_PTR(ap->ip, whichfork);
> +
> + if (XFS_IFORK_FORMAT(ap->ip, whichfork) == XFS_DINODE_FMT_BTREE)
> + return be16_to_cpu(ifp->if_broot->bb_level) + 1;
> + return 1;
> +}
> +
> STATIC int
> xfs_bmap_btalloc(
> struct xfs_bmalloca *ap) /* bmap alloc argument struct */
> @@ -3738,7 +3754,7 @@ xfs_bmap_btalloc(
> args.alignment = 1;
> args.minalignslop = 0;
> }
> - args.minleft = ap->minleft;
> + args.minleft = xfs_bmap_minleft(ap);
> args.wasdel = ap->wasdel;
> args.resv = XFS_AG_RESV_NONE;
> args.datatype = ap->datatype;
> @@ -4493,15 +4509,6 @@ xfs_bmapi_write(
>
> XFS_STATS_INC(mp, xs_blk_mapw);
>
> - if (*firstblock == NULLFSBLOCK) {
> - if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE)
> - bma.minleft = be16_to_cpu(ifp->if_broot->bb_level) + 1;
> - else
> - bma.minleft = 1;
> - } else {
> - bma.minleft = 0;
> - }
> -
> if (!(ifp->if_flags & XFS_IFEXTENTS)) {
> error = xfs_iread_extents(tp, ip, whichfork);
> if (error)
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index d9e0b1db4cdb..36a7f36f5f38 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -48,7 +48,6 @@ struct xfs_bmalloca {
> int logflags;/* flags for transaction logging */
>
> xfs_extlen_t total; /* total blocks needed for xaction */
> - xfs_extlen_t minleft; /* amount must be left after alloc */
> bool eof; /* set if allocating past last extent */
> bool wasdel; /* replacing a delayed allocation */
> bool aeof; /* allocated space at eof */
> --
> 2.11.0
>
> --
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next prev parent reply other threads:[~2017-04-17 14:19 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 8:05 fix space reservations underneath xfs_bmapi_write Christoph Hellwig
2017-04-13 8:05 ` [PATCH 01/10] xfs: introduce xfs_trans_blk_res Christoph Hellwig
2017-04-13 18:28 ` Brian Foster
2017-04-13 8:05 ` [PATCH 02/10] xfs: rewrite xfs_da_grow_inode_int Christoph Hellwig
2017-04-13 18:28 ` Brian Foster
2017-04-13 8:05 ` [PATCH 03/10] xfs: remove the XFS_BMAPI_CONTIG flag Christoph Hellwig
2017-04-13 18:28 ` Brian Foster
2017-04-13 8:05 ` [PATCH 04/10] xfs: remove an unsafe retry in xfs_bmbt_alloc_block Christoph Hellwig
2017-04-13 18:30 ` Brian Foster
2017-04-14 7:46 ` Christoph Hellwig
2017-04-17 14:19 ` Brian Foster
2017-04-18 7:54 ` Christoph Hellwig
2017-04-18 14:18 ` Brian Foster
2017-04-25 7:30 ` Christoph Hellwig
2017-04-25 12:11 ` Brian Foster
2017-04-13 8:05 ` [PATCH 05/10] xfs: remove the total argument to xfs_bmap_local_to_extents Christoph Hellwig
2017-04-17 14:19 ` Brian Foster
2017-04-13 8:05 ` [PATCH 06/10] xfs: fix bmap minleft calculation Christoph Hellwig
2017-04-17 14:19 ` Brian Foster [this message]
2017-04-18 7:59 ` Christoph Hellwig
2017-04-13 8:05 ` [PATCH 07/10] xfs: fix space reservation in xfs_bmbt_alloc_block Christoph Hellwig
2017-04-17 14:19 ` Brian Foster
2017-04-13 8:05 ` [PATCH 08/10] xfs: introduce a XFS_BMAPI_BESTEFFORT flag Christoph Hellwig
2017-04-17 18:08 ` Brian Foster
2017-04-18 7:58 ` Christoph Hellwig
2017-04-18 14:18 ` Brian Foster
2017-04-13 8:05 ` [PATCH 09/10] xfs: kill the dop_low flag Christoph Hellwig
2017-04-17 18:08 ` Brian Foster
2017-04-13 8:05 ` [PATCH 10/10] xfs: remove xfs_bmap_alloc Christoph Hellwig
2017-04-17 18:08 ` Brian Foster
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