From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org, john.g.garry@oracle.com
Subject: Re: [PATCH 9/9] xfs: return -ENOSPC rather than NULLFSBLOCK from allocation functions
Date: Thu, 5 Oct 2023 05:21:11 -0700 [thread overview]
Message-ID: <ZR6qN3ZguKiZy7pC@infradead.org> (raw)
In-Reply-To: <20231004001943.349265-10-david@fromorbit.com>
> Make sure we don't have a repeat of this situation by changing the
> API to explicitly return ENOSPC when we fail to allocate. If we fail
> to capture this correctly, it will lead to failures being noticed
> either by ENOSPC escaping to userspace or by causing filesystem
> shutdowns when allocations failure where they really shouldn't.
Yes, the retur 0 on ENOSPC has driven me crazy in the past.
Note that you now also drop the XXX comment on xfs_alloc_vextent_finish
about this.
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 27c62f303488..13fda27fabcb 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -1157,9 +1157,9 @@ xfs_alloc_ag_vextent_small(
> * Can't do the allocation, give up.
> */
> if (flen < args->minlen) {
> - args->agbno = NULLAGBLOCK;
> trace_xfs_alloc_small_notenough(args);
> - flen = 0;
> + error = -ENOSPC;
> + goto error;
I suspect a direct return -ENOSPC here might be better, as we already
have the trace_xfs_alloc_small_notenough tracepoint here, and also
hitting trace_xfs_alloc_small_error wouldn't make much sense (and be
a pointles behavior change).
Looking at the callers of xfs_alloc_ag_vextent_small, both seem to
need an update to check for -ENOSPC explicitly, as they first check
for an error and only after that for i == 0 || len == 0 to detect
the no space case.
> @@ -3375,14 +3370,7 @@ xfs_alloc_vextent_finish(
> args->agno > minimum_agno))
> args->tp->t_highest_agno = args->agno;
>
> - /*
> - * If the allocation failed with an error or we had an ENOSPC result,
> - * preserve the returned error whilst also marking the allocation result
> - * as "no extent allocated". This ensures that callers that fail to
> - * capture the error will still treat it as a failed allocation.
> - */
> - if (alloc_error || args->agbno == NULLAGBLOCK) {
> - args->fsbno = NULLFSBLOCK;
> + if (alloc_error) {
> error = alloc_error;
> goto out_drop_perag;
> }
Maybe throw in a
ASSERT(args->agbno != NULLAGBLOCK);
after this conditional to catch backporting errors and the like?
prev parent reply other threads:[~2023-10-05 13:56 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-04 0:19 [RFC PATCH 0/9] xfs: push perags further into allocation routines Dave Chinner
2023-10-04 0:19 ` [PATCH 1/9] xfs: split xfs_bmap_btalloc_at_eof() Dave Chinner
2023-10-04 23:41 ` Darrick J. Wong
2023-10-05 9:41 ` Christoph Hellwig
2023-10-04 0:19 ` [PATCH 2/9] xfs: contiguous EOF allocation across AGs Dave Chinner
2023-10-05 9:43 ` Christoph Hellwig
2023-10-06 5:27 ` Darrick J. Wong
2023-10-04 0:19 ` [PATCH 3/9] xfs: select the AG with the largest contiguous space Dave Chinner
2023-10-05 9:45 ` Christoph Hellwig
2023-10-05 9:46 ` Christoph Hellwig
2023-10-24 16:25 ` Darrick J. Wong
2023-10-04 0:19 ` [PATCH 4/9] xfs: push the perag outwards in initial allocation Dave Chinner
2023-10-05 11:57 ` Christoph Hellwig
2023-10-04 0:19 ` [PATCH 5/9] xfs: aligned EOF allocations don't need to scan AGs anymore Dave Chinner
2023-10-05 11:59 ` Christoph Hellwig
2023-10-06 5:55 ` Darrick J. Wong
2023-10-04 0:19 ` [PATCH 6/9] xfs: use agno/agbno in xfs_alloc_vextent functions Dave Chinner
2023-10-05 12:02 ` Christoph Hellwig
2023-10-06 5:56 ` Darrick J. Wong
2023-10-04 0:19 ` [PATCH 7/9] xfs: caller perag always supplied to xfs_alloc_vextent_near_bno Dave Chinner
2023-10-05 12:02 ` Christoph Hellwig
2023-10-06 5:59 ` Darrick J. Wong
2023-10-04 0:19 ` [PATCH 8/9] xfs: collapse near and exact bno allocation Dave Chinner
2023-10-05 12:03 ` Christoph Hellwig
2023-10-06 6:01 ` Darrick J. Wong
2023-10-04 0:19 ` [PATCH 9/9] xfs: return -ENOSPC rather than NULLFSBLOCK from allocation functions Dave Chinner
2023-10-05 12:21 ` Christoph Hellwig [this message]
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