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block: remove REQ_NOWAIT_INLINE
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We had a few issues with this code, and there's still a problem around
how we deal with error handling for chained/split bios. For now, just
revert the code and we'll try again with a thoroug solution. This
reverts commits:

e15c2ff ("block: fix O_DIRECT error handling for bio fragments")
0eb6ddf ("block: Fix __blkdev_direct_IO() for bio fragments")
6a43074 ("block: properly handle IOCB_NOWAIT for async O_DIRECT IO")
893a1c9 ("blk-mq: allow REQ_NOWAIT to return an error inline")

Signed-off-by: Jens Axboe <axboe@kernel.dk>
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axboe committed Aug 15, 2019
1 parent 99c79f6 commit 7b6620d
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Showing 3 changed files with 8 additions and 54 deletions.
8 changes: 2 additions & 6 deletions block/blk-mq.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1958,13 +1958,9 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
rq = blk_mq_get_request(q, bio, &data);
if (unlikely(!rq)) {
rq_qos_cleanup(q, bio);

cookie = BLK_QC_T_NONE;
if (bio->bi_opf & REQ_NOWAIT_INLINE)
cookie = BLK_QC_T_EAGAIN;
else if (bio->bi_opf & REQ_NOWAIT)
if (bio->bi_opf & REQ_NOWAIT)
bio_wouldblock_error(bio);
return cookie;
return BLK_QC_T_NONE;
}

trace_block_getrq(q, bio, bio->bi_opf);
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49 changes: 5 additions & 44 deletions fs/block_dev.c
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Original file line number Diff line number Diff line change
Expand Up @@ -345,24 +345,15 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
struct bio *bio;
bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
bool is_read = (iov_iter_rw(iter) == READ), is_sync;
bool nowait = (iocb->ki_flags & IOCB_NOWAIT) != 0;
loff_t pos = iocb->ki_pos;
blk_qc_t qc = BLK_QC_T_NONE;
gfp_t gfp;
int ret;
int ret = 0;

if ((pos | iov_iter_alignment(iter)) &
(bdev_logical_block_size(bdev) - 1))
return -EINVAL;

if (nowait)
gfp = GFP_NOWAIT;
else
gfp = GFP_KERNEL;

bio = bio_alloc_bioset(gfp, nr_pages, &blkdev_dio_pool);
if (!bio)
return -EAGAIN;
bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, &blkdev_dio_pool);

dio = container_of(bio, struct blkdev_dio, bio);
dio->is_sync = is_sync = is_sync_kiocb(iocb);
Expand All @@ -384,7 +375,6 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
if (!is_poll)
blk_start_plug(&plug);

ret = 0;
for (;;) {
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = pos >> 9;
Expand All @@ -409,14 +399,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
task_io_account_write(bio->bi_iter.bi_size);
}

/*
* Tell underlying layer to not block for resource shortage.
* And if we would have blocked, return error inline instead
* of through the bio->bi_end_io() callback.
*/
if (nowait)
bio->bi_opf |= (REQ_NOWAIT | REQ_NOWAIT_INLINE);

dio->size += bio->bi_iter.bi_size;
pos += bio->bi_iter.bi_size;

nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
Expand All @@ -428,13 +411,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
polled = true;
}

dio->size += bio->bi_iter.bi_size;
qc = submit_bio(bio);
if (qc == BLK_QC_T_EAGAIN) {
dio->size -= bio->bi_iter.bi_size;
ret = -EAGAIN;
goto error;
}

if (polled)
WRITE_ONCE(iocb->ki_cookie, qc);
Expand All @@ -455,19 +432,8 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
atomic_inc(&dio->ref);
}

dio->size += bio->bi_iter.bi_size;
qc = submit_bio(bio);
if (qc == BLK_QC_T_EAGAIN) {
dio->size -= bio->bi_iter.bi_size;
ret = -EAGAIN;
goto error;
}

bio = bio_alloc(gfp, nr_pages);
if (!bio) {
ret = -EAGAIN;
goto error;
}
submit_bio(bio);
bio = bio_alloc(GFP_KERNEL, nr_pages);
}

if (!is_poll)
Expand All @@ -487,18 +453,13 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
}
__set_current_state(TASK_RUNNING);

out:
if (!ret)
ret = blk_status_to_errno(dio->bio.bi_status);
if (likely(!ret))
ret = dio->size;

bio_put(&dio->bio);
return ret;
error:
if (!is_poll)
blk_finish_plug(&plug);
goto out;
}

static ssize_t
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5 changes: 1 addition & 4 deletions include/linux/blk_types.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -311,7 +311,6 @@ enum req_flag_bits {
__REQ_RAHEAD, /* read ahead, can fail anytime */
__REQ_BACKGROUND, /* background IO */
__REQ_NOWAIT, /* Don't wait if request will block */
__REQ_NOWAIT_INLINE, /* Return would-block error inline */
/*
* When a shared kthread needs to issue a bio for a cgroup, doing
* so synchronously can lead to priority inversions as the kthread
Expand Down Expand Up @@ -346,7 +345,6 @@ enum req_flag_bits {
#define REQ_RAHEAD (1ULL << __REQ_RAHEAD)
#define REQ_BACKGROUND (1ULL << __REQ_BACKGROUND)
#define REQ_NOWAIT (1ULL << __REQ_NOWAIT)
#define REQ_NOWAIT_INLINE (1ULL << __REQ_NOWAIT_INLINE)
#define REQ_CGROUP_PUNT (1ULL << __REQ_CGROUP_PUNT)

#define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP)
Expand Down Expand Up @@ -420,13 +418,12 @@ static inline int op_stat_group(unsigned int op)

typedef unsigned int blk_qc_t;
#define BLK_QC_T_NONE -1U
#define BLK_QC_T_EAGAIN -2U
#define BLK_QC_T_SHIFT 16
#define BLK_QC_T_INTERNAL (1U << 31)

static inline bool blk_qc_t_valid(blk_qc_t cookie)
{
return cookie != BLK_QC_T_NONE && cookie != BLK_QC_T_EAGAIN;
return cookie != BLK_QC_T_NONE;
}

static inline unsigned int blk_qc_t_to_queue_num(blk_qc_t cookie)
Expand Down

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