Commit 12ef8301 authored Jan 09, 2017 by Christoph Hellwig Committed by Darrick J. Wong Jan 09, 2017

xfs: don't rely on ->total in xfs_alloc_space_available



->total is a bit of an odd parameter passed down to the low-level
allocator all the way from the high-level callers.  It's supposed to
contain the maximum number of blocks to be allocated for the whole
transaction [1].

But in xfs_iomap_write_allocate we only convert existing delayed
allocations and thus only have a minimal block reservation for the
current transaction, so xfs_alloc_space_available can't use it for
the allocation decisions.  Use the maximum of args->total and the
calculated block requirement to make a decision.  We probably should
get rid of args->total eventually and instead apply ->minleft more
broadly, but that will require some extensive changes all over.

[1] which creates lots of confusion as most callers don't decrement it
once doing a first allocation.  But that's for a separate series.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

parent 54fee133

fs/xfs/libxfs/xfs_alloc.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -1995,7 +1995,7 @@ xfs_alloc_space_available(
		int flags)
		{
		struct xfs_perag *pag = args->pag;
		xfs_extlen_t longest;
		xfs_extlen_t alloc_len, longest;
		xfs_extlen_t reservation; /* blocks that are still reserved */
		int available;

		@@ -2005,15 +2005,16 @@ xfs_alloc_space_available(
		reservation = xfs_ag_resv_needed(pag, args->resv);

		/* do we have enough contiguous free space for the allocation? */
		alloc_len = args->minlen + (args->alignment - 1) + args->minalignslop;
		longest = xfs_alloc_longest_free_extent(args->mp, pag, min_free,
		reservation);
		if ((args->minlen + args->alignment + args->minalignslop - 1) > longest)
		if (longest < alloc_len)
		return false;

		/* do we have enough free space remaining for the allocation? */
		available = (int)(pag->pagf_freeblks + pag->pagf_flcount -
		reservation - min_free - args->minleft);
		if (available < (int)args->total)
		if (available < (int)max(args->total, alloc_len))
		return false;

		/*