From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-bcache@vger.kernel.org, linux-xtensa@linux-xtensa.org,
linux-nvdimm@lists.01.org, linux-s390@vger.kernel.org,
dm-devel@redhat.com, linux-nvme@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
linux-m68k@lists.linux-m68k.org, linuxppc-dev@lists.ozlabs.org,
drbd-dev@lists.linbit.com
Subject: [PATCH 18/20] block: refator submit_bio_noacct
Date: Wed, 1 Jul 2020 10:59:45 +0200 [thread overview]
Message-ID: <20200701085947.3354405-19-hch@lst.de> (raw)
In-Reply-To: <20200701085947.3354405-1-hch@lst.de>
Split out a __submit_bio_noacct helper for the actual de-recursion
algorithm, and simplify the loop by using a continue when we can't
enter the queue for a bio.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/blk-core.c | 143 +++++++++++++++++++++++++----------------------
1 file changed, 75 insertions(+), 68 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index ff9a88d2d244cb..57b5dc00d44cb1 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1084,6 +1084,74 @@ static blk_qc_t __submit_bio(struct bio *bio)
return ret;
}
+/*
+ * The loop in this function may be a bit non-obvious, and so deserves some
+ * explanation:
+ *
+ * - Before entering the loop, bio->bi_next is NULL (as all callers ensure
+ * that), so we have a list with a single bio.
+ * - We pretend that we have just taken it off a longer list, so we assign
+ * bio_list to a pointer to the bio_list_on_stack, thus initialising the
+ * bio_list of new bios to be added. ->submit_bio() may indeed add some more
+ * bios through a recursive call to submit_bio_noacct. If it did, we find a
+ * non-NULL value in bio_list and re-enter the loop from the top.
+ * - In this case we really did just take the bio of the top of the list (no
+ * pretending) and so remove it from bio_list, and call into ->submit_bio()
+ * again.
+ *
+ * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio.
+ * bio_list_on_stack[1] contains bios that were submitted before the current
+ * ->submit_bio_bio, but that haven't been processed yet.
+ */
+static blk_qc_t __submit_bio_noacct(struct bio *bio)
+{
+ struct bio_list bio_list_on_stack[2];
+ blk_qc_t ret = BLK_QC_T_NONE;
+
+ BUG_ON(bio->bi_next);
+
+ bio_list_init(&bio_list_on_stack[0]);
+ current->bio_list = bio_list_on_stack;
+
+ do {
+ struct request_queue *q = bio->bi_disk->queue;
+ struct bio_list lower, same;
+
+ if (unlikely(bio_queue_enter(bio) != 0))
+ continue;
+
+ /*
+ * Create a fresh bio_list for all subordinate requests.
+ */
+ bio_list_on_stack[1] = bio_list_on_stack[0];
+ bio_list_init(&bio_list_on_stack[0]);
+
+ ret = __submit_bio(bio);
+
+ /*
+ * Sort new bios into those for a lower level and those for the
+ * same level.
+ */
+ bio_list_init(&lower);
+ bio_list_init(&same);
+ while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
+ if (q == bio->bi_disk->queue)
+ bio_list_add(&same, bio);
+ else
+ bio_list_add(&lower, bio);
+
+ /*
+ * Now assemble so we handle the lowest level first.
+ */
+ bio_list_merge(&bio_list_on_stack[0], &lower);
+ bio_list_merge(&bio_list_on_stack[0], &same);
+ bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
+ } while ((bio = bio_list_pop(&bio_list_on_stack[0])));
+
+ current->bio_list = NULL;
+ return ret;
+}
+
/**
* submit_bio_noacct - re-submit a bio to the block device layer for I/O
* @bio: The bio describing the location in memory and on the device.
@@ -1095,82 +1163,21 @@ static blk_qc_t __submit_bio(struct bio *bio)
*/
blk_qc_t submit_bio_noacct(struct bio *bio)
{
- /*
- * bio_list_on_stack[0] contains bios submitted by the current
- * ->submit_bio.
- * bio_list_on_stack[1] contains bios that were submitted before the
- * current ->submit_bio_bio, but that haven't been processed yet.
- */
- struct bio_list bio_list_on_stack[2];
- blk_qc_t ret = BLK_QC_T_NONE;
-
if (!submit_bio_checks(bio))
- goto out;
+ return BLK_QC_T_NONE;
/*
- * We only want one ->submit_bio to be active at a time, else
- * stack usage with stacked devices could be a problem. So use
- * current->bio_list to keep a list of requests submited by a
- * ->submit_bio method. current->bio_list is also used as a
- * flag to say if submit_bio_noacct is currently active in this
- * task or not. If it is NULL, then no make_request is active. If
- * it is non-NULL, then a make_request is active, and new requests
- * should be added at the tail
+ * We only want one ->submit_bio to be active at a time, else stack
+ * usage with stacked devices could be a problem. Use current->bio_list
+ * to collect a list of requests submited by a ->submit_bio method while
+ * it is active, and then process them after it returned.
*/
if (current->bio_list) {
bio_list_add(¤t->bio_list[0], bio);
- goto out;
+ return BLK_QC_T_NONE;
}
- /* following loop may be a bit non-obvious, and so deserves some
- * explanation.
- * Before entering the loop, bio->bi_next is NULL (as all callers
- * ensure that) so we have a list with a single bio.
- * We pretend that we have just taken it off a longer list, so
- * we assign bio_list to a pointer to the bio_list_on_stack,
- * thus initialising the bio_list of new bios to be
- * added. ->submit_bio() may indeed add some more bios
- * through a recursive call to submit_bio_noacct. If it
- * did, we find a non-NULL value in bio_list and re-enter the loop
- * from the top. In this case we really did just take the bio
- * of the top of the list (no pretending) and so remove it from
- * bio_list, and call into ->submit_bio() again.
- */
- BUG_ON(bio->bi_next);
- bio_list_init(&bio_list_on_stack[0]);
- current->bio_list = bio_list_on_stack;
- do {
- struct request_queue *q = bio->bi_disk->queue;
-
- if (likely(bio_queue_enter(bio) == 0)) {
- struct bio_list lower, same;
-
- /* Create a fresh bio_list for all subordinate requests */
- bio_list_on_stack[1] = bio_list_on_stack[0];
- bio_list_init(&bio_list_on_stack[0]);
- ret = __submit_bio(bio);
-
- /* sort new bios into those for a lower level
- * and those for the same level
- */
- bio_list_init(&lower);
- bio_list_init(&same);
- while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
- if (q == bio->bi_disk->queue)
- bio_list_add(&same, bio);
- else
- bio_list_add(&lower, bio);
- /* now assemble so we handle the lowest level first */
- bio_list_merge(&bio_list_on_stack[0], &lower);
- bio_list_merge(&bio_list_on_stack[0], &same);
- bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
- }
- bio = bio_list_pop(&bio_list_on_stack[0]);
- } while (bio);
- current->bio_list = NULL; /* deactivate */
-
-out:
- return ret;
+ return __submit_bio_noacct(bio);
}
EXPORT_SYMBOL(submit_bio_noacct);
--
2.26.2
next prev parent reply other threads:[~2020-07-01 9:40 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 8:59 rename ->make_request_fn and move it to the block_device_operations v2 Christoph Hellwig
2020-07-01 8:59 ` [PATCH 01/20] nfblock: stop using ->queuedata Christoph Hellwig
2020-07-01 8:59 ` [PATCH 02/20] simdisk: " Christoph Hellwig
2020-07-01 8:59 ` [PATCH 03/20] drbd: " Christoph Hellwig
2020-07-01 8:59 ` [PATCH 04/20] null_blk: stop using ->queuedata for bio mode Christoph Hellwig
2020-07-01 8:59 ` [PATCH 05/20] ps3vram: stop using ->queuedata Christoph Hellwig
2020-07-01 8:59 ` [PATCH 06/20] rsxx: " Christoph Hellwig
2020-07-01 8:59 ` [PATCH 07/20] umem: " Christoph Hellwig
2020-07-01 8:59 ` [PATCH 08/20] zram: " Christoph Hellwig
2020-07-01 8:59 ` [PATCH 09/20] bcache: stop setting ->queuedata Christoph Hellwig
2020-07-02 14:47 ` Coly Li
2020-07-01 8:59 ` [PATCH 10/20] dm: stop using ->queuedata Christoph Hellwig
2020-07-01 17:24 ` Mike Snitzer
2020-07-01 8:59 ` [PATCH 11/20] fs: remove a weird comment in submit_bh_wbc Christoph Hellwig
2020-07-01 8:59 ` [PATCH 12/20] block: remove the request_queue argument from blk_queue_split Christoph Hellwig
2020-07-02 6:14 ` Song Liu
2020-07-01 8:59 ` [PATCH 13/20] block: tidy up a warning in bio_check_ro Christoph Hellwig
2020-07-01 8:59 ` [PATCH 14/20] block: remove the NULL queue check in generic_make_request_checks Christoph Hellwig
2020-07-01 8:59 ` [PATCH 15/20] block: remove the nr_sectors variable " Christoph Hellwig
2020-07-01 8:59 ` [PATCH 16/20] block: move ->make_request_fn to struct block_device_operations Christoph Hellwig
2020-07-01 16:08 ` Dan Williams
2020-07-02 14:48 ` Coly Li
2020-07-01 8:59 ` [PATCH 17/20] block: rename generic_make_request to submit_bio_noacct Christoph Hellwig
2020-07-02 14:51 ` Coly Li
2020-07-02 18:22 ` Song Liu
2020-07-01 8:59 ` Christoph Hellwig [this message]
2020-07-01 8:59 ` [PATCH 19/20] block: shortcut __submit_bio_noacct for blk-mq drivers Christoph Hellwig
2020-07-01 8:59 ` [PATCH 20/20] block: remove direct_make_request Christoph Hellwig
2020-07-01 13:43 ` rename ->make_request_fn and move it to the block_device_operations v2 Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2020-06-29 19:39 rename ->make_request_fn and move it to the block_device_operations Christoph Hellwig
2020-06-29 19:39 ` [PATCH 18/20] block: refator submit_bio_noacct Christoph Hellwig
2020-07-02 14:10 ` Qian Cai
2020-07-02 15:14 ` Christoph Hellwig
2020-07-02 15:52 ` Naresh Kamboju
2020-07-02 15:15 ` Naresh Kamboju
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