[PATCH v3 11/18] xfs: randomly do sparse inode allocations in DEBUG mode

[Brian Foster]

Sparse inode allocations generally only occur when full inode chunk
allocation fails. This requires some level of filesystem space usage and
fragmentation.

For filesystems formatted with sparse inode chunks enabled, do random
sparse inode chunk allocs when compiled in DEBUG mode to increase test
coverage.

Signed-off-by: Brian Foster <bfoster at redhat.com>
---
 fs/xfs/libxfs/xfs_ialloc.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 090d114..3e5d3eb 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -652,9 +652,18 @@ xfs_ialloc_ag_alloc(
 
 	struct xfs_perag *pag;
 
+#ifdef DEBUG
+	int		do_sparse = 0;
+
+	/* randomly do sparse inode allocations */
+	if (xfs_sb_version_hassparseinodes(&tp->t_mountp->m_sb))
+		do_sparse = prandom_u32() & 1;
+#endif
+
 	memset(&args, 0, sizeof(args));
 	args.tp = tp;
 	args.mp = tp->t_mountp;
+	args.fsbno = NULLFSBLOCK;
 
 	/*
 	 * Locking will ensure that we don't have two callers in here
@@ -675,6 +684,10 @@ xfs_ialloc_ag_alloc(
 	agno = be32_to_cpu(agi->agi_seqno);
 	args.agbno = XFS_AGINO_TO_AGBNO(args.mp, newino) +
 		     args.mp->m_ialloc_blks;
+#ifdef DEBUG
+	if (do_sparse)
+		goto sparse_alloc;
+#endif
 	if (likely(newino != NULLAGINO &&
 		  (args.agbno < be32_to_cpu(agi->agi_length)))) {
 		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
@@ -713,8 +726,7 @@ xfs_ialloc_ag_alloc(
 		 * subsequent requests.
 		 */
 		args.minalignslop = 0;
-	} else
-		args.fsbno = NULLFSBLOCK;
+	}
 
 	if (unlikely(args.fsbno == NULLFSBLOCK)) {
 		/*
@@ -769,6 +781,9 @@ xfs_ialloc_ag_alloc(
 	 * Finally, try a sparse allocation if the filesystem supports it and
 	 * the sparse allocation length is smaller than a full chunk.
 	 */
+#ifdef DEBUG
+sparse_alloc:
+#endif
 	if (xfs_sb_version_hassparseinodes(&args.mp->m_sb) &&
 	    args.mp->m_ialloc_min_blks < args.mp->m_ialloc_blks &&
 	    args.fsbno == NULLFSBLOCK) {
-- 
1.8.3.1