btrfs: nowait aio: Correct assignment of pos
Assigning pos for usage early messes up in append mode, where the pos is re-assigned in generic_write_checks(). Assign pos later to get the correct position to write from iocb->ki_pos. Since check_can_nocow also uses the value of pos, we shift generic_write_checks() before check_can_nocow(). Checks with IOCB_DIRECT are present in generic_write_checks(), so checking for IOCB_NOWAIT is enough. Also, put locking sequence in the fast path. This fixes a user visible bug, as reported: "apparently breaks several shell related features on my system. In zsh history stopped working, because no new entries are added anymore. I fist noticed the issue when I tried to build mplayer. It uses a shell script to generate a help_mp.h file: [...] Here is a simple testcase: % echo "foo" >> test % echo "foo" >> test % cat test foo % " Fixes: edf064e7 ("btrfs: nowait aio support") CC: Jens Axboe <axboe@kernel.dk> Reported-by:Markus Trippelsdorf <markus@trippelsdorf.de> Link: https://lkml.kernel.org/r/20170704042306.GA274@x4 Signed-off-by:
Goldwyn Rodrigues <rgoldwyn@suse.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
parent
f95a0d6a
Please register or sign in to comment