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fs/adfs: map: fix map scanning 

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 <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Russell King 2019-12-09 11:09:04 +00:00 committed by Al Viro
parent f6f14a0d71
commit f93793fd73
1 changed files with 7 additions and 2 deletions
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9
fs/adfs/map.c
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@ -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)