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UBIFS: fix recovery bug 

UBIFS did not recovery in a situation in which it could
have. The relevant function assumed there could not be
more nodes in an eraseblock after a corrupted node, but
in fact the last (NAND) page written might contain anything.
The correct approach is to check for empty space (0xFF bytes)
from then on.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
This commit is contained in:
Adrian Hunter 2009-03-20 11:09:04 +01:00 committed by Artem Bityutskiy
parent 963f0cf6d1
commit de0975781a
1 changed files with 23 additions and 47 deletions
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70
fs/ubifs/recovery.c
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@ -425,59 +425,35 @@ static void clean_buf(const struct ubifs_info *c, void **buf, int lnum,
* @lnum: LEB number of the LEB from which @buf was read
* @offs: offset from which @buf was read
*
* This function scans @buf for more nodes and returns %0 is a node is found and
* %1 if no more nodes are found.
* This function ensures that the corrupted node at @offs is the last thing
* written to a LEB. This function returns %1 if more data is not found and
* %0 if more data is found.
*/
static int no_more_nodes(const struct ubifs_info *c, void *buf, int len,
int lnum, int offs)
{
int skip, next_offs = 0;
struct ubifs_ch *ch = buf;
int skip, dlen = le32_to_cpu(ch->len);
if (len > UBIFS_DATA_NODE_SZ) {
struct ubifs_ch *ch = buf;
int dlen = le32_to_cpu(ch->len);
if (ch->node_type == UBIFS_DATA_NODE && dlen >= UBIFS_CH_SZ &&
dlen <= UBIFS_MAX_DATA_NODE_SZ)
/* The corrupt node looks like a data node */
next_offs = ALIGN(offs + dlen, 8);
/* Check for empty space after the corrupt node's common header */
skip = ALIGN(offs + UBIFS_CH_SZ, c->min_io_size) - offs;
if (is_empty(buf + skip, len - skip))
return 1;
/*
* The area after the common header size is not empty, so the common
* header must be intact. Check it.
*/
if (ubifs_check_node(c, buf, lnum, offs, 1, 0) != -EUCLEAN) {
dbg_rcvry("unexpected bad common header at %d:%d", lnum, offs);
return 0;
}
if (c->min_io_size == 1)
skip = 8;
else
skip = ALIGN(offs + 1, c->min_io_size) - offs;
offs += skip;
buf += skip;
len -= skip;
while (len > 8) {
struct ubifs_ch *ch = buf;
uint32_t magic = le32_to_cpu(ch->magic);
int ret;
if (magic == UBIFS_NODE_MAGIC) {
ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
if (ret == SCANNED_A_NODE || ret > 0) {
/*
* There is a small chance this is just data in
* a data node, so check that possibility. e.g.
* this is part of a file that itself contains
* a UBIFS image.
*/
if (next_offs && offs + le32_to_cpu(ch->len) <=
next_offs)
continue;
dbg_rcvry("unexpected node at %d:%d", lnum,
offs);
return 0;
}
}
offs += 8;
buf += 8;
len -= 8;
}
return 1;
/* Now we know the corrupt node's length we can skip over it */
skip = ALIGN(offs + dlen, c->min_io_size) - offs;
/* After which there should be empty space */
if (is_empty(buf + skip, len - skip))
return 1;
dbg_rcvry("unexpected data at %d:%d", lnum, offs + skip);
return 0;
}
/**