[Cluster-devel] [PATCH 04/11] gfs2: Minor gfs2_free_extlen cleanup

[Andreas Gruenbacher <agruenba@redhat.com>]

Limit the n_unaligned argument of gfs2_unaligned_extlen to the number of
blocks to scan so that the len argument can never underrun.

Slightly simplify the unaligned block logic in gfs2_free_extlen.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/gfs2/rgrp.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 2ce46e372b020..f06755dae951e 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -335,8 +335,6 @@ static bool gfs2_unaligned_extlen(struct gfs2_rbm *rbm, u32 n_unaligned, u32 *le
 		if (res != GFS2_BLKST_FREE)
 			return true;
 		(*len)--;
-		if (*len == 0)
-			return true;
 		if (gfs2_rbm_incr(rbm))
 			return true;
 	}
@@ -362,7 +360,6 @@ static bool gfs2_unaligned_extlen(struct gfs2_rbm *rbm, u32 n_unaligned, u32 *le
 static u32 gfs2_free_extlen(const struct gfs2_rbm *rrbm, u32 len)
 {
 	struct gfs2_rbm rbm = *rrbm;
-	u32 n_unaligned = rbm.offset & 3;
 	u32 size = len;
 	u32 bytes;
 	u32 chunk_size;
@@ -370,11 +367,14 @@ static u32 gfs2_free_extlen(const struct gfs2_rbm *rrbm, u32 len)
 	u64 block;
 	struct gfs2_bitmap *bi;
 
-	if (n_unaligned &&
-	    gfs2_unaligned_extlen(&rbm, 4 - n_unaligned, &len))
-		goto out;
+	/* Deal with unaligned bits at the front */
+	if (rbm.offset & 3) {
+		u32 n_unaligned = min(4 - (rbm.offset & 3), len);
+
+		if (gfs2_unaligned_extlen(&rbm, n_unaligned, &len))
+			goto out;
+	}
 
-	n_unaligned = len & 3;
 	/* Start is now byte aligned */
 	while (len > 3) {
 		bi = rbm_bi(&rbm);
@@ -392,20 +392,16 @@ static u32 gfs2_free_extlen(const struct gfs2_rbm *rrbm, u32 len)
 		BUG_ON(len < chunk_size);
 		len -= chunk_size;
 		block = gfs2_rbm_to_block(&rbm);
-		if (gfs2_rbm_from_block(&rbm, block + chunk_size)) {
-			n_unaligned = 0;
-			break;
-		}
-		if (ptr) {
-			n_unaligned = 3;
+		if (gfs2_rbm_from_block(&rbm, block + chunk_size))
+			goto out;
+		if (ptr)
 			break;
-		}
-		n_unaligned = len & 3;
 	}
 
 	/* Deal with any bits left over@the end */
-	if (n_unaligned)
-		gfs2_unaligned_extlen(&rbm, n_unaligned, &len);
+	if (len)
+		gfs2_unaligned_extlen(&rbm, len, &len);
+
 out:
 	return size - len;
 }
-- 
2.20.1