Commit 69b195be authored by Akinobu Mita's avatar Akinobu Mita Committed by Al Viro

bfs: fix bitmap size argument to find_first_zero_bit()

The usage of find_first_zero_bit() in bfs_create() is wrong for two
reasons.

The bitmap size argument to find_first_zero_bit() is info->si_lasti but
the correct bitmap size is info->si_lasti + 1 as info->si_lasti is the
last valid index in info->si_imap bitmap.

Another problem is that it is impossible to detect that info->si_imap
bitmap is full because there is an off-by-one bug in the return value
check for find_first_zero_bit().  If no zero bits exist in info->si_imap,
find_first_zero_bit() returns info->si_lasti.  But the check can't catch
it due to the off-by-one.
Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Acked-by: default avatar"Tigran A. Aivazian" <tigran@aivazian.fsnet.co.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent c212f9aa
......@@ -97,7 +97,7 @@ static int bfs_create(struct inode *dir, struct dentry *dentry, int mode,
if (!inode)
return -ENOSPC;
mutex_lock(&info->bfs_lock);
ino = find_first_zero_bit(info->si_imap, info->si_lasti);
ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
if (ino > info->si_lasti) {
mutex_unlock(&info->bfs_lock);
iput(inode);
......
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