jbd: Fail to load a journal if it is too short

Due to on disk corruption, it can happen that journal is too short. Fail
to load it in such case so that we don't oops somewhere later.

Reported-by: Nageswara R Sastry <rnsastry@linux.vnet.ibm.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index 737f7246a4b5ddc750b4a5198928f4b5afacc193..94a64a199a63a5b6ab389450d701a43e325582bf 100644 (file)
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -848,6 +848,12 @@ static int journal_reset(journal_t *journal)
 
        first = be32_to_cpu(sb->s_first);
        last = be32_to_cpu(sb->s_maxlen);
+       if (first + JFS_MIN_JOURNAL_BLOCKS > last + 1) {
+               printk(KERN_ERR "JBD: Journal too short (blocks %lu-%lu).\n",
+                      first, last);
+               journal_fail_superblock(journal);
+               return -EINVAL;
+       }
 
        journal->j_first = first;
        journal->j_last = last;