Commit 30265117 authored Jun 06, 2014 by Jan Kara Committed by Dave Chinner Jun 06, 2014

xfs: Fix rounding in xfs_alloc_fix_len()



Rounding in xfs_alloc_fix_len() is wrong. As the comment states, the
result should be a number of a form (k*prod+mod) however due to sign
mistake the result is different. As a result allocations on raid arrays
could be misaligned in some cases.

This also seems to fix occasional assertion failure:
	XFS_WANT_CORRUPTED_GOTO(rlen <= flen, error0)
in xfs_alloc_ag_vextent_size().

Also add an assertion that the result of xfs_alloc_fix_len() is of
expected form.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

parent 448011e2

fs/xfs/xfs_alloc.c

+8 −10

Original line number	Original line	Diff line number	Diff line
	@@ -257,16 +257,14 @@ xfs_alloc_fix_len(
	k = rlen % args->prod;		k = rlen % args->prod;
	if (k == args->mod)		if (k == args->mod)
	return;		return;
	if (k > args->mod) {		if (k > args->mod)
	if ((int)(rlen = rlen - k - args->mod) < (int)args->minlen)		rlen = rlen - (k - args->mod);
	return;		else
	} else {		rlen = rlen - args->prod + (args->mod - k);
	if ((int)(rlen = rlen - args->prod - (args->mod - k)) <		if ((int)rlen < (int)args->minlen)
	(int)args->minlen)
	return;		return;
	}		ASSERT(rlen >= args->minlen && rlen <= args->maxlen);
	ASSERT(rlen >= args->minlen);		ASSERT(rlen % args->prod == args->mod);
	ASSERT(rlen <= args->maxlen);
	args->len = rlen;		args->len = rlen;
	}		}