direct-io: Fix sleep in atomic due to sync AIO

Commit e864f39569 "fs: add RWF_DSYNC aand RWF_SYNC" added additional
way for direct IO to become synchronous and thus trigger fsync from the
IO completion handler. Then commit 9830f4be15 "fs: Use RWF_* flags for
AIO operations" allowed these flags to be set for AIO as well. However
that commit forgot to update the condition checking whether the IO
completion handling should be defered to a workqueue and thus AIO DIO
with RWF_[D]SYNC set will call fsync() from IRQ context resulting in
sleep in atomic.

Fix the problem by checking directly iocb flags (the same way as it is
done in dio_complete()) instead of checking all conditions that could
lead to IO being synchronous.

CC: Christoph Hellwig <[email protected]>
CC: Goldwyn Rodrigues <[email protected]>
CC: [email protected]
Reported-by: Mark Rutland <[email protected]>
Tested-by: Mark Rutland <[email protected]>
Fixes: 9830f4be15
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Jan Kara 2018-02-26 12:51:43 +01:00 • committed by Jens Axboe
commit d9c10e5b88

View file

@ -1274,8 +1274,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
*/
if (dio->is_async && iov_iter_rw(iter) == WRITE) {
retval = 0;
if ((iocb->ki_filp->f_flags & O_DSYNC) ||
IS_SYNC(iocb->ki_filp->f_mapping->host))
if (iocb->ki_flags & IOCB_DSYNC)
retval = dio_set_defer_completion(dio);
else if (!dio->inode->i_sb->s_dio_done_wq) {
/*