From: Jens Axboe <axboe@kernel.dk> To: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, Jens Axboe <axboe@kernel.dk> Subject: [PATCH 03/15] block: add bio_set_polled() helper Date: Wed, 16 Jan 2019 10:49:51 -0700 Message-ID: <20190116175003.17880-4-axboe@kernel.dk> (raw) In-Reply-To: <20190116175003.17880-1-axboe@kernel.dk> 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. Signed-off-by: Jens Axboe <axboe@kernel.dk> --- fs/block_dev.c | 4 ++-- 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 5415579f3e14..2ebd2a0d7789 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -233,7 +233,7 @@ __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 (;;) { @@ -401,7 +401,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES); if (!nr_pages) { if (iocb->ki_flags & IOCB_HIPRI) - bio->bi_opf |= REQ_HIPRI; + bio_set_polled(bio, iocb); qc = submit_bio(bio); WRITE_ONCE(iocb->ki_cookie, qc); diff --git a/include/linux/bio.h b/include/linux/bio.h index 7380b094dcca..f6f0a2b3cbc8 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -823,5 +823,19 @@ 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 */ -- 2.17.1
next prev parent reply index Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-01-16 17:49 [PATCHSET v5] io_uring IO interface Jens Axboe 2019-01-16 17:49 ` [PATCH 01/15] fs: add an iopoll method to struct file_operations Jens Axboe 2019-01-16 17:49 ` [PATCH 02/15] block: wire up block device iopoll method Jens Axboe 2019-01-16 17:49 ` Jens Axboe [this message] 2019-01-16 17:49 ` [PATCH 04/15] iomap: wire up the " Jens Axboe 2019-01-16 17:49 ` [PATCH 05/15] Add io_uring IO interface Jens Axboe 2019-01-17 12:02 ` Roman Penyaev 2019-01-17 13:54 ` Jens Axboe 2019-01-17 14:34 ` Roman Penyaev 2019-01-17 14:54 ` Jens Axboe 2019-01-17 15:19 ` Roman Penyaev 2019-01-17 12:48 ` Roman Penyaev 2019-01-17 14:01 ` Jens Axboe 2019-01-17 20:03 ` Jeff Moyer 2019-01-17 20:09 ` Jens Axboe 2019-01-17 20:14 ` Jens Axboe 2019-01-17 20:50 ` Jeff Moyer 2019-01-17 20:53 ` Jens Axboe 2019-01-17 21:02 ` Jeff Moyer 2019-01-17 21:17 ` Jens Axboe 2019-01-17 21:21 ` Jeff Moyer 2019-01-17 21:27 ` Jens Axboe 2019-01-18 8:23 ` Roman Penyaev 2019-01-16 17:49 ` [PATCH 06/15] io_uring: add fsync support Jens Axboe 2019-01-16 17:49 ` [PATCH 07/15] io_uring: support for IO polling Jens Axboe 2019-01-16 17:49 ` [PATCH 08/15] fs: add fget_many() and fput_many() Jens Axboe 2019-01-16 17:49 ` [PATCH 09/15] io_uring: use fget/fput_many() for file references Jens Axboe 2019-01-16 17:49 ` [PATCH 10/15] io_uring: batch io_kiocb allocation Jens Axboe 2019-01-16 17:49 ` [PATCH 11/15] block: implement bio helper to add iter bvec pages to bio Jens Axboe 2019-01-16 17:50 ` [PATCH 12/15] io_uring: add support for pre-mapped user IO buffers Jens Axboe 2019-01-16 20:53 ` Dave Chinner 2019-01-16 21:20 ` Jens Axboe 2019-01-16 22:09 ` Dave Chinner 2019-01-16 22:21 ` Jens Axboe 2019-01-16 23:09 ` Dave Chinner 2019-01-16 23:17 ` Jens Axboe 2019-01-16 22:13 ` Jens Axboe 2019-01-16 17:50 ` [PATCH 13/15] io_uring: add submission polling Jens Axboe 2019-01-16 17:50 ` [PATCH 14/15] io_uring: add file registration Jens Axboe 2019-01-16 17:50 ` [PATCH 15/15] io_uring: add io_uring_event cache hit information Jens Axboe -- strict thread matches above, loose matches on Subject: below -- 2019-01-10 2:43 [PATCHSET v2] io_uring IO interface Jens Axboe 2019-01-10 2:43 ` [PATCH 03/15] block: add bio_set_polled() helper Jens Axboe
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20190116175003.17880-4-axboe@kernel.dk \ --to=axboe@kernel.dk \ --cc=avi@scylladb.com \ --cc=hch@lst.de \ --cc=jmoyer@redhat.com \ --cc=linux-aio@kvack.org \ --cc=linux-arch@vger.kernel.org \ --cc=linux-block@vger.kernel.org \ --cc=linux-fsdevel@vger.kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
Linux-Block Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/linux-block/0 linux-block/git/0.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 linux-block linux-block/ https://lore.kernel.org/linux-block \ linux-block@vger.kernel.org public-inbox-index linux-block Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.kernel.vger.linux-block AGPL code for this site: git clone https://public-inbox.org/public-inbox.git