[10/41] fs/adfs: map: fix map scanning

Commit Message

Russell King (Oracle) Dec. 9, 2019, 11:09 a.m. UTC

When scanning the map for a fragment id, we need to keep track of the
free space links, so we don't inadvertently believe that the freespace
link is a valid fragment id.

Signed-off-by: Russell King <[e-mail]>
---
 fs/adfs/map.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Patch

diff --git a/fs/adfs/map.c b/fs/adfs/map.c
index 82e1bf101fe6..a81de80c45c1 100644
--- a/fs/adfs/map.c
+++ b/fs/adfs/map.c
@@ -72,9 +72,12 @@  static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
 	const u32 idmask = (1 << idlen) - 1;
 	unsigned char *map = dm->dm_bh->b_data;
 	unsigned int start = dm->dm_startbit;
-	unsigned int fragend;
+	unsigned int freelink, fragend;
 	u32 frag;
 
+	frag = GET_FRAG_ID(map, 8, idmask & 0x7fff);
+	freelink = frag ? 8 + frag : 0;
+
 	do {
 		frag = GET_FRAG_ID(map, start, idmask);
 
@@ -82,7 +85,9 @@  static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
 		if (fragend >= endbit)
 			goto error;
 
-		if (frag == frag_id) {
+		if (start == freelink) {
+			freelink += frag & 0x7fff;
+		} else if (frag == frag_id) {
 			unsigned int length = fragend + 1 - start;
 
 			if (*offset < length)