[PATCH v5 14/18] 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 | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index 0aad400..f719706 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -606,9 +606,18 @@ xfs_ialloc_ag_alloc(
 	struct xfs_inobt_rec_incore rec;
 	struct xfs_perag *pag;
 
+	int		do_sparse = 0;
+
+#ifdef DEBUG
+	/* 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
@@ -629,6 +638,8 @@ 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;
+	if (do_sparse)
+		goto sparse_alloc;
 	if (likely(newino != NULLAGINO &&
 		  (args.agbno < be32_to_cpu(agi->agi_length)))) {
 		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
@@ -667,8 +678,7 @@ xfs_ialloc_ag_alloc(
 		 * subsequent requests.
 		 */
 		args.minalignslop = 0;
-	} else
-		args.fsbno = NULLFSBLOCK;
+	}
 
 	if (unlikely(args.fsbno == NULLFSBLOCK)) {
 		/*
@@ -726,6 +736,7 @@ xfs_ialloc_ag_alloc(
 	if (xfs_sb_version_hassparseinodes(&args.mp->m_sb) &&
 	    args.mp->m_ialloc_min_blks < args.mp->m_ialloc_blks &&
 	    args.fsbno == NULLFSBLOCK) {
+sparse_alloc:
 		args.type = XFS_ALLOCTYPE_NEAR_BNO;
 		args.agbno = be32_to_cpu(agi->agi_root);
 		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
-- 
1.9.3