directio: add block polling support

This adds support for sync O_DIRECT read/write poll support.

Signed-off-by: Jens Axboe <axboe@fb.com>
[hch: split from a larger patch, minor updates]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 3ae0e0427191..7025029c666f 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -109,6 +109,8 @@ struct dio_submit {
 struct dio {
         int flags;                      /* doesn't change */
         int rw;
+        blk_qc_t bio_cookie;
+        struct block_device *bio_bdev;
         struct inode *inode;
         loff_t i_size;                  /* i_size when submitted */
         dio_iodone_t *end_io;           /* IO completion function */
@@ -397,11 +399,14 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
         if (dio->is_async && dio->rw == READ && dio->should_dirty)
                 bio_set_pages_dirty(bio);
 
-        if (sdio->submit_io)
+        if (sdio->submit_io) {
                 sdio->submit_io(dio->rw, bio, dio->inode,
                                sdio->logical_offset_in_bio);
-        else
-                submit_bio(dio->rw, bio);
+                dio->bio_cookie = BLK_QC_T_NONE;
+        } else {
+                dio->bio_cookie = submit_bio(dio->rw, bio);
+                dio->bio_bdev = bio->bi_bdev;
+        }
 
         sdio->bio = NULL;
         sdio->boundary = 0;
@@ -440,7 +445,8 @@ static struct bio *dio_await_one(struct dio *dio)
                 __set_current_state(TASK_UNINTERRUPTIBLE);
                 dio->waiter = current;
                 spin_unlock_irqrestore(&dio->bio_lock, flags);
-                io_schedule();
+                if (!blk_poll(bdev_get_queue(dio->bio_bdev), dio->bio_cookie))
+                        io_schedule();
                 /* wake up sets us TASK_RUNNING */
                 spin_lock_irqsave(&dio->bio_lock, flags);
                 dio->waiter = NULL;