diff options
| author | Jens Axboe <axboe@kernel.dk> | 2018-12-21 17:10:46 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-02-24 16:20:17 +0100 |
| commit | 0bbb280d7b767e7c86a5adfc87c76a6f09ab0423 (patch) | |
| tree | 5e2b9970b0144b91c5b8def73827aacca82845f4 | |
| parent | block: wire up block device iopoll method (diff) | |
| download | linux-0bbb280d7b767e7c86a5adfc87c76a6f09ab0423.tar.xz linux-0bbb280d7b767e7c86a5adfc87c76a6f09ab0423.zip | |
block: add bio_set_polled() helper
For the upcoming async polled IO, we can't sleep allocating requests.
If we do, then we introduce a deadlock where the submitter already
has async polled IO in-flight, but can't wait for them to complete
since polled requests must be active found and reaped.
Utilize the helper in the blockdev DIRECT_IO code.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | fs/block_dev.c | 4 | ||||
| -rw-r--r-- | include/linux/bio.h | 14 |
2 files changed, 16 insertions, 2 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index 1fe498b08f1b..e9faa52bb489 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -248,7 +248,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, task_io_account_write(ret); } if (iocb->ki_flags & IOCB_HIPRI) - bio.bi_opf |= REQ_HIPRI; + bio_set_polled(&bio, iocb); qc = submit_bio(&bio); for (;;) { @@ -419,7 +419,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) bool polled = false; if (iocb->ki_flags & IOCB_HIPRI) { - bio->bi_opf |= REQ_HIPRI; + bio_set_polled(bio, iocb); polled = true; } diff --git a/include/linux/bio.h b/include/linux/bio.h index bdd11d4c2f05..bb6090aa165d 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -826,5 +826,19 @@ static inline int bio_integrity_add_page(struct bio *bio, struct page *page, #endif /* CONFIG_BLK_DEV_INTEGRITY */ +/* + * Mark a bio as polled. Note that for async polled IO, the caller must + * expect -EWOULDBLOCK if we cannot allocate a request (or other resources). + * We cannot block waiting for requests on polled IO, as those completions + * must be found by the caller. This is different than IRQ driven IO, where + * it's safe to wait for IO to complete. + */ +static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb) +{ + bio->bi_opf |= REQ_HIPRI; + if (!is_sync_kiocb(kiocb)) + bio->bi_opf |= REQ_NOWAIT; +} + #endif /* CONFIG_BLOCK */ #endif /* __LINUX_BIO_H */ |