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>

diff --git a/fs/bfs/inode.c b/fs/bfs/inode.c
index 1d2bfaf..cc4062d 100644 (file)
--- 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;