swh:1:snp:38ae39f9fd01a4b0ef06fab5668b65bf4c2aca03
Revision ad0eab9293485d1c06237e9249f6d4dfa3d93d4d authored by Paul Mackerras on 13 November 2014, 09:15:23 UTC, committed by Al Viro on 13 November 2014, 18:28:55 UTC
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.

Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1 parent 7e8631e
History
Tip revision: 0cdd776ec92c0fec768c7079331804d3e52d4b27 authored by Linus Torvalds on 15 May 2022, 15:08:51 UTC
Merge tag 'driver-core-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Tip revision: 0cdd776
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