On 9.03.20 г. 23:32 ч., Omar Sandoval wrote:
> From: Omar Sandoval <osandov@xxxxxx>
>
> If we submit orig_bio in btrfs_submit_direct_hook(), we never increment
> pending_bios. Then, if btrfs_submit_dio_bio() fails, we decrement
> pending_bios to -1, and we never complete orig_bio. Fix it by
> initializing pending_bios to 1 instead of incrementing later.
nit: I'd rephrase this paragraph to put the emphasis on when this could
happen, which is when the write falls entirely within a chunk's stripe
(i.e doesn't span 64k region in case of having a block group with a
profile different than SINGLE) or doesn't span a chunk in case of a
profile different than SINGLE.
>
> Fixing this exposes another bug: we put orig_bio prematurely and then
> put it again from end_io. Fix it by not putting orig_bio.
>
> After this change, pending_bios is really more of a reference count, but
> I'll leave that cleanup separate to keep the fix small.
>
> Fixes: e65e15355429 ("btrfs: fix panic caused by direct IO")
> Signed-off-by: Omar Sandoval <osandov@xxxxxx>
The changes look good, I just wonder why didn't this trip earlier...
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
