diff options
| author | Paul Mackerras <paulus@samba.org> | 2014-11-13 20:15:23 +1100 |
|---|---|---|
| committer | Luis Henriques <luis.henriques@canonical.com> | 2014-11-27 11:21:48 +0000 |
| commit | bdba73df4adfce9a2b1f4eab0dc4b46779e56721 (patch) | |
| tree | fdf45fbd4da973e2ae54b9163908a36681f01702 | |
| parent | 219e9b7b06efa99fab075ffacbf419d644319736 (diff) | |
Fix thinko in iov_iter_single_seg_count
commit ad0eab9293485d1c06237e9249f6d4dfa3d93d4d upstream.
The branches of the if (i->type & ITER_BVEC) statement in
iov_iter_single_seg_count() are the wrong way around; if ITER_BVEC is
clear then we use i->bvec, when we should be using i->iov. This fixes
it.
In my case, the symptom that this caused was that a KVM guest doing
filesystem operations on a virtual disk would result in one of qemu's
threads on the host going into an infinite loop in
generic_perform_write(). The loop would hit the copied == 0 case and
call iov_iter_single_seg_count() to reduce the number of bytes to try
to process, but because of the error, iov_iter_single_seg_count()
would just return i->count and the loop made no progress and continued
forever.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
| -rw-r--r-- | mm/iov_iter.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/iov_iter.c b/mm/iov_iter.c index 9a09f2034fcc..141dcf796d28 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -699,9 +699,9 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i) if (i->nr_segs == 1) return i->count; else if (i->type & ITER_BVEC) - return min(i->count, i->iov->iov_len - i->iov_offset); - else return min(i->count, i->bvec->bv_len - i->iov_offset); + else + return min(i->count, i->iov->iov_len - i->iov_offset); } EXPORT_SYMBOL(iov_iter_single_seg_count); |