bfs: check that filesystem fits on the blockdevice

Since all sanity checks rely on the validity of s_start which gets only
checked to be smaller than s_end, we should also check if s_end is sane.
Now we also try to retrieve the last block of the filesystem, which is
computed by s_end.  If this fails, something is bogus.

Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Acked-by: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/bfs/inode.c b/fs/bfs/inode.c
index 1d2bfafcad7c..cc4062d12ca2 100644
--- a/fs/bfs/inode.c
+++ b/fs/bfs/inode.c
@@ -390,6 +390,18 @@ static int bfs_fill_super(struct super_block *s, void *data, int silent)
                         - le32_to_cpu(bfs_sb->s_start)) >> BFS_BSIZE_BITS;
         info->si_freei = 0;
         info->si_lf_eblk = 0;
+
+        /* can we read the last block? */
+        bh = sb_bread(s, info->si_blocks - 1);
+        if (!bh) {
+                printf("Last block not available: %lu\n", info->si_blocks - 1);
+                iput(inode);
+                ret = -EIO;
+                kfree(info->si_imap);
+                goto out;
+        }
+        brelse(bh);
+
         bh = NULL;
         for (i = BFS_ROOT_INO; i <= info->si_lasti; i++) {
                 struct bfs_inode *di;