xfs: fix broken variable-sized allocation detection in xfs_rtallocate_extent_block
This function tries to find a suitable free space extent starting from
a particular rtbitmap block. Some time ago, I added a clamping function
to prevent the free space scans from running off the end of the bitmap,
but I didn't quite get the logic right.
Let's say there's an allocation request with a minlen of 5 and a maxlen
of 32 and we're scanning the last rtbitmap block. If we come within 4
rtx of the end of the rt volume, maxlen will get clamped to 4. If the
next 3 rtx are free, we could have satisfied the allocation, but the
code setting partial besti/bestlen for "minlen < maxlen" will think that
we're doing a non-variable allocation and ignore it.
The root of this problem is overwriting maxlen; I should have stuffed
the results in a different variable, which would not have introduced
this bug.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
1 file changed
