Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1212 insertions, 0 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
new file mode 100644
index 000000000..6eaf2b0ad
--- /dev/null
+++ b/block/blk-core.c
@@ -0,0 +1,1212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 1994,      Karl Keyte: Added support for disk statistics
+ * Elevator latency, (C) 2000  Andrea Arcangeli <andrea@suse.de> SuSE
+ * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
+ * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
+ *	-  July2000
+ * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
+ */
+
+/*
+ * This handles all read/write requests to block devices
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/blk-pm.h>
+#include <linux/blk-integrity.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/kernel_stat.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/fault-inject.h>
+#include <linux/list_sort.h>
+#include <linux/delay.h>
+#include <linux/ratelimit.h>
+#include <linux/pm_runtime.h>
+#include <linux/t10-pi.h>
+#include <linux/debugfs.h>
+#include <linux/bpf.h>
+#include <linux/part_stat.h>
+#include <linux/sched/sysctl.h>
+#include <linux/blk-crypto.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/block.h>
+
+#include "blk.h"
+#include "blk-mq-sched.h"
+#include "blk-pm.h"
+#include "blk-cgroup.h"
+#include "blk-throttle.h"
+
+struct dentry *blk_debugfs_root;
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert);
+
+DEFINE_IDA(blk_queue_ida);
+
+/*
+ * For queue allocation
+ */
+struct kmem_cache *blk_requestq_cachep;
+struct kmem_cache *blk_requestq_srcu_cachep;
+
+/*
+ * Controlling structure to kblockd
+ */
+static struct workqueue_struct *kblockd_workqueue;
+
+/**
+ * blk_queue_flag_set - atomically set a queue flag
+ * @flag: flag to be set
+ * @q: request queue
+ */
+void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
+{
+	set_bit(flag, &q->queue_flags);
+}
+EXPORT_SYMBOL(blk_queue_flag_set);
+
+/**
+ * blk_queue_flag_clear - atomically clear a queue flag
+ * @flag: flag to be cleared
+ * @q: request queue
+ */
+void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
+{
+	clear_bit(flag, &q->queue_flags);
+}
+EXPORT_SYMBOL(blk_queue_flag_clear);
+
+/**
+ * blk_queue_flag_test_and_set - atomically test and set a queue flag
+ * @flag: flag to be set
+ * @q: request queue
+ *
+ * Returns the previous value of @flag - 0 if the flag was not set and 1 if
+ * the flag was already set.
+ */
+bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q)
+{
+	return test_and_set_bit(flag, &q->queue_flags);
+}
+EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);
+
+#define REQ_OP_NAME(name) [REQ_OP_##name] = #name
+static const char *const blk_op_name[] = {
+	REQ_OP_NAME(READ),
+	REQ_OP_NAME(WRITE),
+	REQ_OP_NAME(FLUSH),
+	REQ_OP_NAME(DISCARD),
+	REQ_OP_NAME(SECURE_ERASE),
+	REQ_OP_NAME(ZONE_RESET),
+	REQ_OP_NAME(ZONE_RESET_ALL),
+	REQ_OP_NAME(ZONE_OPEN),
+	REQ_OP_NAME(ZONE_CLOSE),
+	REQ_OP_NAME(ZONE_FINISH),
+	REQ_OP_NAME(ZONE_APPEND),
+	REQ_OP_NAME(WRITE_ZEROES),
+	REQ_OP_NAME(DRV_IN),
+	REQ_OP_NAME(DRV_OUT),
+};
+#undef REQ_OP_NAME
+
+/**
+ * blk_op_str - Return string XXX in the REQ_OP_XXX.
+ * @op: REQ_OP_XXX.
+ *
+ * Description: Centralize block layer function to convert REQ_OP_XXX into
+ * string format. Useful in the debugging and tracing bio or request. For
+ * invalid REQ_OP_XXX it returns string "UNKNOWN".
+ */
+inline const char *blk_op_str(enum req_op op)
+{
+	const char *op_str = "UNKNOWN";
+
+	if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op])
+		op_str = blk_op_name[op];
+
+	return op_str;
+}
+EXPORT_SYMBOL_GPL(blk_op_str);
+
+static const struct {
+	int		errno;
+	const char	*name;
+} blk_errors[] = {
+	[BLK_STS_OK]		= { 0,		"" },
+	[BLK_STS_NOTSUPP]	= { -EOPNOTSUPP, "operation not supported" },
+	[BLK_STS_TIMEOUT]	= { -ETIMEDOUT,	"timeout" },
+	[BLK_STS_NOSPC]		= { -ENOSPC,	"critical space allocation" },
+	[BLK_STS_TRANSPORT]	= { -ENOLINK,	"recoverable transport" },
+	[BLK_STS_TARGET]	= { -EREMOTEIO,	"critical target" },
+	[BLK_STS_NEXUS]		= { -EBADE,	"critical nexus" },
+	[BLK_STS_MEDIUM]	= { -ENODATA,	"critical medium" },
+	[BLK_STS_PROTECTION]	= { -EILSEQ,	"protection" },
+	[BLK_STS_RESOURCE]	= { -ENOMEM,	"kernel resource" },
+	[BLK_STS_DEV_RESOURCE]	= { -EBUSY,	"device resource" },
+	[BLK_STS_AGAIN]		= { -EAGAIN,	"nonblocking retry" },
+	[BLK_STS_OFFLINE]	= { -ENODEV,	"device offline" },
+
+	/* device mapper special case, should not leak out: */
+	[BLK_STS_DM_REQUEUE]	= { -EREMCHG, "dm internal retry" },
+
+	/* zone device specific errors */
+	[BLK_STS_ZONE_OPEN_RESOURCE]	= { -ETOOMANYREFS, "open zones exceeded" },
+	[BLK_STS_ZONE_ACTIVE_RESOURCE]	= { -EOVERFLOW, "active zones exceeded" },
+
+	/* everything else not covered above: */
+	[BLK_STS_IOERR]		= { -EIO,	"I/O" },
+};
+
+blk_status_t errno_to_blk_status(int errno)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
+		if (blk_errors[i].errno == errno)
+			return (__force blk_status_t)i;
+	}
+
+	return BLK_STS_IOERR;
+}
+EXPORT_SYMBOL_GPL(errno_to_blk_status);
+
+int blk_status_to_errno(blk_status_t status)
+{
+	int idx = (__force int)status;
+
+	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
+		return -EIO;
+	return blk_errors[idx].errno;
+}
+EXPORT_SYMBOL_GPL(blk_status_to_errno);
+
+const char *blk_status_to_str(blk_status_t status)
+{
+	int idx = (__force int)status;
+
+	if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
+		return "<null>";
+	return blk_errors[idx].name;
+}
+
+/**
+ * blk_sync_queue - cancel any pending callbacks on a queue
+ * @q: the queue
+ *
+ * Description:
+ *     The block layer may perform asynchronous callback activity
+ *     on a queue, such as calling the unplug function after a timeout.
+ *     A block device may call blk_sync_queue to ensure that any
+ *     such activity is cancelled, thus allowing it to release resources
+ *     that the callbacks might use. The caller must already have made sure
+ *     that its ->submit_bio will not re-add plugging prior to calling
+ *     this function.
+ *
+ *     This function does not cancel any asynchronous activity arising
+ *     out of elevator or throttling code. That would require elevator_exit()
+ *     and blkcg_exit_queue() to be called with queue lock initialized.
+ *
+ */
+void blk_sync_queue(struct request_queue *q)
+{
+	del_timer_sync(&q->timeout);
+	cancel_work_sync(&q->timeout_work);
+}
+EXPORT_SYMBOL(blk_sync_queue);
+
+/**
+ * blk_set_pm_only - increment pm_only counter
+ * @q: request queue pointer
+ */
+void blk_set_pm_only(struct request_queue *q)
+{
+	atomic_inc(&q->pm_only);
+}
+EXPORT_SYMBOL_GPL(blk_set_pm_only);
+
+void blk_clear_pm_only(struct request_queue *q)
+{
+	int pm_only;
+
+	pm_only = atomic_dec_return(&q->pm_only);
+	WARN_ON_ONCE(pm_only < 0);
+	if (pm_only == 0)
+		wake_up_all(&q->mq_freeze_wq);
+}
+EXPORT_SYMBOL_GPL(blk_clear_pm_only);
+
+/**
+ * blk_put_queue - decrement the request_queue refcount
+ * @q: the request_queue structure to decrement the refcount for
+ *
+ * Decrements the refcount of the request_queue kobject. When this reaches 0
+ * we'll have blk_release_queue() called.
+ *
+ * Context: Any context, but the last reference must not be dropped from
+ *          atomic context.
+ */
+void blk_put_queue(struct request_queue *q)
+{
+	kobject_put(&q->kobj);
+}
+EXPORT_SYMBOL(blk_put_queue);
+
+void blk_queue_start_drain(struct request_queue *q)
+{
+	/*
+	 * When queue DYING flag is set, we need to block new req
+	 * entering queue, so we call blk_freeze_queue_start() to
+	 * prevent I/O from crossing blk_queue_enter().
+	 */
+	blk_freeze_queue_start(q);
+	if (queue_is_mq(q))
+		blk_mq_wake_waiters(q);
+	/* Make blk_queue_enter() reexamine the DYING flag. */
+	wake_up_all(&q->mq_freeze_wq);
+}
+
+/**
+ * blk_queue_enter() - try to increase q->q_usage_counter
+ * @q: request queue pointer
+ * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM
+ */
+int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
+{
+	const bool pm = flags & BLK_MQ_REQ_PM;
+
+	while (!blk_try_enter_queue(q, pm)) {
+		if (flags & BLK_MQ_REQ_NOWAIT)
+			return -EAGAIN;
+
+		/*
+		 * read pair of barrier in blk_freeze_queue_start(), we need to
+		 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and
+		 * reading .mq_freeze_depth or queue dying flag, otherwise the
+		 * following wait may never return if the two reads are
+		 * reordered.
+		 */
+		smp_rmb();
+		wait_event(q->mq_freeze_wq,
+			   (!q->mq_freeze_depth &&
+			    blk_pm_resume_queue(pm, q)) ||
+			   blk_queue_dying(q));
+		if (blk_queue_dying(q))
+			return -ENODEV;
+	}
+
+	return 0;
+}
+
+int __bio_queue_enter(struct request_queue *q, struct bio *bio)
+{
+	while (!blk_try_enter_queue(q, false)) {
+		struct gendisk *disk = bio->bi_bdev->bd_disk;
+
+		if (bio->bi_opf & REQ_NOWAIT) {
+			if (test_bit(GD_DEAD, &disk->state))
+				goto dead;
+			bio_wouldblock_error(bio);
+			return -EAGAIN;
+		}
+
+		/*
+		 * read pair of barrier in blk_freeze_queue_start(), we need to
+		 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and
+		 * reading .mq_freeze_depth or queue dying flag, otherwise the
+		 * following wait may never return if the two reads are
+		 * reordered.
+		 */
+		smp_rmb();
+		wait_event(q->mq_freeze_wq,
+			   (!q->mq_freeze_depth &&
+			    blk_pm_resume_queue(false, q)) ||
+			   test_bit(GD_DEAD, &disk->state));
+		if (test_bit(GD_DEAD, &disk->state))
+			goto dead;
+	}
+
+	return 0;
+dead:
+	bio_io_error(bio);
+	return -ENODEV;
+}
+
+void blk_queue_exit(struct request_queue *q)
+{
+	percpu_ref_put(&q->q_usage_counter);
+}
+
+static void blk_queue_usage_counter_release(struct percpu_ref *ref)
+{
+	struct request_queue *q =
+		container_of(ref, struct request_queue, q_usage_counter);
+
+	wake_up_all(&q->mq_freeze_wq);
+}
+
+static void blk_rq_timed_out_timer(struct timer_list *t)
+{
+	struct request_queue *q = from_timer(q, t, timeout);
+
+	kblockd_schedule_work(&q->timeout_work);
+}
+
+static void blk_timeout_work(struct work_struct *work)
+{
+}
+
+struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu)
+{
+	struct request_queue *q;
+
+	q = kmem_cache_alloc_node(blk_get_queue_kmem_cache(alloc_srcu),
+			GFP_KERNEL | __GFP_ZERO, node_id);
+	if (!q)
+		return NULL;
+
+	if (alloc_srcu) {
+		blk_queue_flag_set(QUEUE_FLAG_HAS_SRCU, q);
+		if (init_srcu_struct(q->srcu) != 0)
+			goto fail_q;
+	}
+
+	q->last_merge = NULL;
+
+	q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL);
+	if (q->id < 0)
+		goto fail_srcu;
+
+	q->stats = blk_alloc_queue_stats();
+	if (!q->stats)
+		goto fail_id;
+
+	q->node = node_id;
+
+	atomic_set(&q->nr_active_requests_shared_tags, 0);
+
+	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
+	INIT_WORK(&q->timeout_work, blk_timeout_work);
+	INIT_LIST_HEAD(&q->icq_list);
+
+	kobject_init(&q->kobj, &blk_queue_ktype);
+
+	mutex_init(&q->debugfs_mutex);
+	mutex_init(&q->sysfs_lock);
+	mutex_init(&q->sysfs_dir_lock);
+	spin_lock_init(&q->queue_lock);
+
+	init_waitqueue_head(&q->mq_freeze_wq);
+	mutex_init(&q->mq_freeze_lock);
+
+	/*
+	 * Init percpu_ref in atomic mode so that it's faster to shutdown.
+	 * See blk_register_queue() for details.
+	 */
+	if (percpu_ref_init(&q->q_usage_counter,
+				blk_queue_usage_counter_release,
+				PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
+		goto fail_stats;
+
+	blk_set_default_limits(&q->limits);
+	q->nr_requests = BLKDEV_DEFAULT_RQ;
+
+	return q;
+
+fail_stats:
+	blk_free_queue_stats(q->stats);
+fail_id:
+	ida_free(&blk_queue_ida, q->id);
+fail_srcu:
+	if (alloc_srcu)
+		cleanup_srcu_struct(q->srcu);
+fail_q:
+	kmem_cache_free(blk_get_queue_kmem_cache(alloc_srcu), q);
+	return NULL;
+}
+
+/**
+ * blk_get_queue - increment the request_queue refcount
+ * @q: the request_queue structure to increment the refcount for
+ *
+ * Increment the refcount of the request_queue kobject.
+ *
+ * Context: Any context.
+ */
+bool blk_get_queue(struct request_queue *q)
+{
+	if (unlikely(blk_queue_dying(q)))
+		return false;
+	kobject_get(&q->kobj);
+	return true;
+}
+EXPORT_SYMBOL(blk_get_queue);
+
+#ifdef CONFIG_FAIL_MAKE_REQUEST
+
+static DECLARE_FAULT_ATTR(fail_make_request);
+
+static int __init setup_fail_make_request(char *str)
+{
+	return setup_fault_attr(&fail_make_request, str);
+}
+__setup("fail_make_request=", setup_fail_make_request);
+
+bool should_fail_request(struct block_device *part, unsigned int bytes)
+{
+	return part->bd_make_it_fail && should_fail(&fail_make_request, bytes);
+}
+
+static int __init fail_make_request_debugfs(void)
+{
+	struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
+						NULL, &fail_make_request);
+
+	return PTR_ERR_OR_ZERO(dir);
+}
+
+late_initcall(fail_make_request_debugfs);
+#endif /* CONFIG_FAIL_MAKE_REQUEST */
+
+static inline void bio_check_ro(struct bio *bio)
+{
+	if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) {
+		if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
+			return;
+		pr_warn_ratelimited("Trying to write to read-only block-device %pg\n",
+				    bio->bi_bdev);
+		/* Older lvm-tools actually trigger this */
+	}
+}
+
+static noinline int should_fail_bio(struct bio *bio)
+{
+	if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size))
+		return -EIO;
+	return 0;
+}
+ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);
+
+/*
+ * Check whether this bio extends beyond the end of the device or partition.
+ * This may well happen - the kernel calls bread() without checking the size of
+ * the device, e.g., when mounting a file system.
+ */
+static inline int bio_check_eod(struct bio *bio)
+{
+	sector_t maxsector = bdev_nr_sectors(bio->bi_bdev);
+	unsigned int nr_sectors = bio_sectors(bio);
+
+	if (nr_sectors && maxsector &&
+	    (nr_sectors > maxsector ||
+	     bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
+		pr_info_ratelimited("%s: attempt to access beyond end of device\n"
+				    "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n",
+				    current->comm, bio->bi_bdev, bio->bi_opf,
+				    bio->bi_iter.bi_sector, nr_sectors, maxsector);
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * Remap block n of partition p to block n+start(p) of the disk.
+ */
+static int blk_partition_remap(struct bio *bio)
+{
+	struct block_device *p = bio->bi_bdev;
+
+	if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
+		return -EIO;
+	if (bio_sectors(bio)) {
+		bio->bi_iter.bi_sector += p->bd_start_sect;
+		trace_block_bio_remap(bio, p->bd_dev,
+				      bio->bi_iter.bi_sector -
+				      p->bd_start_sect);
+	}
+	bio_set_flag(bio, BIO_REMAPPED);
+	return 0;
+}
+
+/*
+ * Check write append to a zoned block device.
+ */
+static inline blk_status_t blk_check_zone_append(struct request_queue *q,
+						 struct bio *bio)
+{
+	int nr_sectors = bio_sectors(bio);
+
+	/* Only applicable to zoned block devices */
+	if (!bdev_is_zoned(bio->bi_bdev))
+		return BLK_STS_NOTSUPP;
+
+	/* The bio sector must point to the start of a sequential zone */
+	if (bio->bi_iter.bi_sector & (bdev_zone_sectors(bio->bi_bdev) - 1) ||
+	    !bio_zone_is_seq(bio))
+		return BLK_STS_IOERR;
+
+	/*
+	 * Not allowed to cross zone boundaries. Otherwise, the BIO will be
+	 * split and could result in non-contiguous sectors being written in
+	 * different zones.
+	 */
+	if (nr_sectors > q->limits.chunk_sectors)
+		return BLK_STS_IOERR;
+
+	/* Make sure the BIO is small enough and will not get split */
+	if (nr_sectors > q->limits.max_zone_append_sectors)
+		return BLK_STS_IOERR;
+
+	bio->bi_opf |= REQ_NOMERGE;
+
+	return BLK_STS_OK;
+}
+
+static void __submit_bio(struct bio *bio)
+{
+	struct gendisk *disk = bio->bi_bdev->bd_disk;
+
+	if (unlikely(!blk_crypto_bio_prep(&bio)))
+		return;
+
+	if (!disk->fops->submit_bio) {
+		blk_mq_submit_bio(bio);
+	} else if (likely(bio_queue_enter(bio) == 0)) {
+		disk->fops->submit_bio(bio);
+		blk_queue_exit(disk->queue);
+	}
+}
+
+/*
+ * 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, but that haven't been processed yet.
+ */
+static void __submit_bio_noacct(struct bio *bio)
+{
+	struct bio_list bio_list_on_stack[2];
+
+	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 = bdev_get_queue(bio->bi_bdev);
+		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]);
+
+		__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 == bdev_get_queue(bio->bi_bdev))
+				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;
+}
+
+static void __submit_bio_noacct_mq(struct bio *bio)
+{
+	struct bio_list bio_list[2] = { };
+
+	current->bio_list = bio_list;
+
+	do {
+		__submit_bio(bio);
+	} while ((bio = bio_list_pop(&bio_list[0])));
+
+	current->bio_list = NULL;
+}
+
+void submit_bio_noacct_nocheck(struct bio *bio)
+{
+	blk_cgroup_bio_start(bio);
+	blkcg_bio_issue_init(bio);
+
+	if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
+		trace_block_bio_queue(bio);
+		/*
+		 * Now that enqueuing has been traced, we need to trace
+		 * completion as well.
+		 */
+		bio_set_flag(bio, BIO_TRACE_COMPLETION);
+	}
+
+	/*
+	 * 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(&current->bio_list[0], bio);
+	else if (!bio->bi_bdev->bd_disk->fops->submit_bio)
+		__submit_bio_noacct_mq(bio);
+	else
+		__submit_bio_noacct(bio);
+}
+
+/**
+ * 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.
+ *
+ * This is a version of submit_bio() that shall only be used for I/O that is
+ * resubmitted to lower level drivers by stacking block drivers.  All file
+ * systems and other upper level users of the block layer should use
+ * submit_bio() instead.
+ */
+void submit_bio_noacct(struct bio *bio)
+{
+	struct block_device *bdev = bio->bi_bdev;
+	struct request_queue *q = bdev_get_queue(bdev);
+	blk_status_t status = BLK_STS_IOERR;
+	struct blk_plug *plug;
+
+	might_sleep();
+
+	plug = blk_mq_plug(bio);
+	if (plug && plug->nowait)
+		bio->bi_opf |= REQ_NOWAIT;
+
+	/*
+	 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
+	 * if queue does not support NOWAIT.
+	 */
+	if ((bio->bi_opf & REQ_NOWAIT) && !bdev_nowait(bdev))
+		goto not_supported;
+
+	if (should_fail_bio(bio))
+		goto end_io;
+	bio_check_ro(bio);
+	if (!bio_flagged(bio, BIO_REMAPPED)) {
+		if (unlikely(bio_check_eod(bio)))
+			goto end_io;
+		if (bdev->bd_partno && unlikely(blk_partition_remap(bio)))
+			goto end_io;
+	}
+
+	/*
+	 * Filter flush bio's early so that bio based drivers without flush
+	 * support don't have to worry about them.
+	 */
+	if (op_is_flush(bio->bi_opf) &&
+	    !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
+		bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
+		if (!bio_sectors(bio)) {
+			status = BLK_STS_OK;
+			goto end_io;
+		}
+	}
+
+	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+		bio_clear_polled(bio);
+
+	switch (bio_op(bio)) {
+	case REQ_OP_DISCARD:
+		if (!bdev_max_discard_sectors(bdev))
+			goto not_supported;
+		break;
+	case REQ_OP_SECURE_ERASE:
+		if (!bdev_max_secure_erase_sectors(bdev))
+			goto not_supported;
+		break;
+	case REQ_OP_ZONE_APPEND:
+		status = blk_check_zone_append(q, bio);
+		if (status != BLK_STS_OK)
+			goto end_io;
+		break;
+	case REQ_OP_ZONE_RESET:
+	case REQ_OP_ZONE_OPEN:
+	case REQ_OP_ZONE_CLOSE:
+	case REQ_OP_ZONE_FINISH:
+		if (!bdev_is_zoned(bio->bi_bdev))
+			goto not_supported;
+		break;
+	case REQ_OP_ZONE_RESET_ALL:
+		if (!bdev_is_zoned(bio->bi_bdev) || !blk_queue_zone_resetall(q))
+			goto not_supported;
+		break;
+	case REQ_OP_WRITE_ZEROES:
+		if (!q->limits.max_write_zeroes_sectors)
+			goto not_supported;
+		break;
+	default:
+		break;
+	}
+
+	if (blk_throtl_bio(bio))
+		return;
+	submit_bio_noacct_nocheck(bio);
+	return;
+
+not_supported:
+	status = BLK_STS_NOTSUPP;
+end_io:
+	bio->bi_status = status;
+	bio_endio(bio);
+}
+EXPORT_SYMBOL(submit_bio_noacct);
+
+/**
+ * submit_bio - submit a bio to the block device layer for I/O
+ * @bio: The &struct bio which describes the I/O
+ *
+ * submit_bio() is used to submit I/O requests to block devices.  It is passed a
+ * fully set up &struct bio that describes the I/O that needs to be done.  The
+ * bio will be send to the device described by the bi_bdev field.
+ *
+ * The success/failure status of the request, along with notification of
+ * completion, is delivered asynchronously through the ->bi_end_io() callback
+ * in @bio.  The bio must NOT be touched by the caller until ->bi_end_io() has
+ * been called.
+ */
+void submit_bio(struct bio *bio)
+{
+	if (blkcg_punt_bio_submit(bio))
+		return;
+
+	if (bio_op(bio) == REQ_OP_READ) {
+		task_io_account_read(bio->bi_iter.bi_size);
+		count_vm_events(PGPGIN, bio_sectors(bio));
+	} else if (bio_op(bio) == REQ_OP_WRITE) {
+		count_vm_events(PGPGOUT, bio_sectors(bio));
+	}
+
+	submit_bio_noacct(bio);
+}
+EXPORT_SYMBOL(submit_bio);
+
+/**
+ * bio_poll - poll for BIO completions
+ * @bio: bio to poll for
+ * @iob: batches of IO
+ * @flags: BLK_POLL_* flags that control the behavior
+ *
+ * Poll for completions on queue associated with the bio. Returns number of
+ * completed entries found.
+ *
+ * Note: the caller must either be the context that submitted @bio, or
+ * be in a RCU critical section to prevent freeing of @bio.
+ */
+int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)
+{
+	blk_qc_t cookie = READ_ONCE(bio->bi_cookie);
+	struct block_device *bdev;
+	struct request_queue *q;
+	int ret = 0;
+
+	bdev = READ_ONCE(bio->bi_bdev);
+	if (!bdev)
+		return 0;
+
+	q = bdev_get_queue(bdev);
+	if (cookie == BLK_QC_T_NONE ||
+	    !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+		return 0;
+
+	/*
+	 * As the requests that require a zone lock are not plugged in the
+	 * first place, directly accessing the plug instead of using
+	 * blk_mq_plug() should not have any consequences during flushing for
+	 * zoned devices.
+	 */
+	blk_flush_plug(current->plug, false);
+
+	if (bio_queue_enter(bio))
+		return 0;
+	if (queue_is_mq(q)) {
+		ret = blk_mq_poll(q, cookie, iob, flags);
+	} else {
+		struct gendisk *disk = q->disk;
+
+		if (disk && disk->fops->poll_bio)
+			ret = disk->fops->poll_bio(bio, iob, flags);
+	}
+	blk_queue_exit(q);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(bio_poll);
+
+/*
+ * Helper to implement file_operations.iopoll.  Requires the bio to be stored
+ * in iocb->private, and cleared before freeing the bio.
+ */
+int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob,
+		    unsigned int flags)
+{
+	struct bio *bio;
+	int ret = 0;
+
+	/*
+	 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can
+	 * point to a freshly allocated bio at this point.  If that happens
+	 * we have a few cases to consider:
+	 *
+	 *  1) the bio is beeing initialized and bi_bdev is NULL.  We can just
+	 *     simply nothing in this case
+	 *  2) the bio points to a not poll enabled device.  bio_poll will catch
+	 *     this and return 0
+	 *  3) the bio points to a poll capable device, including but not
+	 *     limited to the one that the original bio pointed to.  In this
+	 *     case we will call into the actual poll method and poll for I/O,
+	 *     even if we don't need to, but it won't cause harm either.
+	 *
+	 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev
+	 * is still allocated. Because partitions hold a reference to the whole
+	 * device bdev and thus disk, the disk is also still valid.  Grabbing
+	 * a reference to the queue in bio_poll() ensures the hctxs and requests
+	 * are still valid as well.
+	 */
+	rcu_read_lock();
+	bio = READ_ONCE(kiocb->private);
+	if (bio)
+		ret = bio_poll(bio, iob, flags);
+	rcu_read_unlock();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iocb_bio_iopoll);
+
+void update_io_ticks(struct block_device *part, unsigned long now, bool end)
+{
+	unsigned long stamp;
+again:
+	stamp = READ_ONCE(part->bd_stamp);
+	if (unlikely(time_after(now, stamp))) {
+		if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now)))
+			__part_stat_add(part, io_ticks, end ? now - stamp : 1);
+	}
+	if (part->bd_partno) {
+		part = bdev_whole(part);
+		goto again;
+	}
+}
+
+unsigned long bdev_start_io_acct(struct block_device *bdev,
+				 unsigned int sectors, enum req_op op,
+				 unsigned long start_time)
+{
+	const int sgrp = op_stat_group(op);
+
+	part_stat_lock();
+	update_io_ticks(bdev, start_time, false);
+	part_stat_inc(bdev, ios[sgrp]);
+	part_stat_add(bdev, sectors[sgrp], sectors);
+	part_stat_local_inc(bdev, in_flight[op_is_write(op)]);
+	part_stat_unlock();
+
+	return start_time;
+}
+EXPORT_SYMBOL(bdev_start_io_acct);
+
+/**
+ * bio_start_io_acct_time - start I/O accounting for bio based drivers
+ * @bio:	bio to start account for
+ * @start_time:	start time that should be passed back to bio_end_io_acct().
+ */
+void bio_start_io_acct_time(struct bio *bio, unsigned long start_time)
+{
+	bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio),
+			   bio_op(bio), start_time);
+}
+EXPORT_SYMBOL_GPL(bio_start_io_acct_time);
+
+/**
+ * bio_start_io_acct - start I/O accounting for bio based drivers
+ * @bio:	bio to start account for
+ *
+ * Returns the start time that should be passed back to bio_end_io_acct().
+ */
+unsigned long bio_start_io_acct(struct bio *bio)
+{
+	return bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio),
+				  bio_op(bio), jiffies);
+}
+EXPORT_SYMBOL_GPL(bio_start_io_acct);
+
+void bdev_end_io_acct(struct block_device *bdev, enum req_op op,
+		      unsigned long start_time)
+{
+	const int sgrp = op_stat_group(op);
+	unsigned long now = READ_ONCE(jiffies);
+	unsigned long duration = now - start_time;
+
+	part_stat_lock();
+	update_io_ticks(bdev, now, true);
+	part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration));
+	part_stat_local_dec(bdev, in_flight[op_is_write(op)]);
+	part_stat_unlock();
+}
+EXPORT_SYMBOL(bdev_end_io_acct);
+
+void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time,
+			      struct block_device *orig_bdev)
+{
+	bdev_end_io_acct(orig_bdev, bio_op(bio), start_time);
+}
+EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped);
+
+/**
+ * blk_lld_busy - Check if underlying low-level drivers of a device are busy
+ * @q : the queue of the device being checked
+ *
+ * Description:
+ *    Check if underlying low-level drivers of a device are busy.
+ *    If the drivers want to export their busy state, they must set own
+ *    exporting function using blk_queue_lld_busy() first.
+ *
+ *    Basically, this function is used only by request stacking drivers
+ *    to stop dispatching requests to underlying devices when underlying
+ *    devices are busy.  This behavior helps more I/O merging on the queue
+ *    of the request stacking driver and prevents I/O throughput regression
+ *    on burst I/O load.
+ *
+ * Return:
+ *    0 - Not busy (The request stacking driver should dispatch request)
+ *    1 - Busy (The request stacking driver should stop dispatching request)
+ */
+int blk_lld_busy(struct request_queue *q)
+{
+	if (queue_is_mq(q) && q->mq_ops->busy)
+		return q->mq_ops->busy(q);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(blk_lld_busy);
+
+int kblockd_schedule_work(struct work_struct *work)
+{
+	return queue_work(kblockd_workqueue, work);
+}
+EXPORT_SYMBOL(kblockd_schedule_work);
+
+int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
+				unsigned long delay)
+{
+	return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
+}
+EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
+
+void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios)
+{
+	struct task_struct *tsk = current;
+
+	/*
+	 * If this is a nested plug, don't actually assign it.
+	 */
+	if (tsk->plug)
+		return;
+
+	plug->mq_list = NULL;
+	plug->cached_rq = NULL;
+	plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT);
+	plug->rq_count = 0;
+	plug->multiple_queues = false;
+	plug->has_elevator = false;
+	plug->nowait = false;
+	INIT_LIST_HEAD(&plug->cb_list);
+
+	/*
+	 * Store ordering should not be needed here, since a potential
+	 * preempt will imply a full memory barrier
+	 */
+	tsk->plug = plug;
+}
+
+/**
+ * blk_start_plug - initialize blk_plug and track it inside the task_struct
+ * @plug:	The &struct blk_plug that needs to be initialized
+ *
+ * Description:
+ *   blk_start_plug() indicates to the block layer an intent by the caller
+ *   to submit multiple I/O requests in a batch.  The block layer may use
+ *   this hint to defer submitting I/Os from the caller until blk_finish_plug()
+ *   is called.  However, the block layer may choose to submit requests
+ *   before a call to blk_finish_plug() if the number of queued I/Os
+ *   exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than
+ *   %BLK_PLUG_FLUSH_SIZE.  The queued I/Os may also be submitted early if
+ *   the task schedules (see below).
+ *
+ *   Tracking blk_plug inside the task_struct will help with auto-flushing the
+ *   pending I/O should the task end up blocking between blk_start_plug() and
+ *   blk_finish_plug(). This is important from a performance perspective, but
+ *   also ensures that we don't deadlock. For instance, if the task is blocking
+ *   for a memory allocation, memory reclaim could end up wanting to free a
+ *   page belonging to that request that is currently residing in our private
+ *   plug. By flushing the pending I/O when the process goes to sleep, we avoid
+ *   this kind of deadlock.
+ */
+void blk_start_plug(struct blk_plug *plug)
+{
+	blk_start_plug_nr_ios(plug, 1);
+}
+EXPORT_SYMBOL(blk_start_plug);
+
+static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
+{
+	LIST_HEAD(callbacks);
+
+	while (!list_empty(&plug->cb_list)) {
+		list_splice_init(&plug->cb_list, &callbacks);
+
+		while (!list_empty(&callbacks)) {
+			struct blk_plug_cb *cb = list_first_entry(&callbacks,
+							  struct blk_plug_cb,
+							  list);
+			list_del(&cb->list);
+			cb->callback(cb, from_schedule);
+		}
+	}
+}
+
+struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
+				      int size)
+{
+	struct blk_plug *plug = current->plug;
+	struct blk_plug_cb *cb;
+
+	if (!plug)
+		return NULL;
+
+	list_for_each_entry(cb, &plug->cb_list, list)
+		if (cb->callback == unplug && cb->data == data)
+			return cb;
+
+	/* Not currently on the callback list */
+	BUG_ON(size < sizeof(*cb));
+	cb = kzalloc(size, GFP_ATOMIC);
+	if (cb) {
+		cb->data = data;
+		cb->callback = unplug;
+		list_add(&cb->list, &plug->cb_list);
+	}
+	return cb;
+}
+EXPORT_SYMBOL(blk_check_plugged);
+
+void __blk_flush_plug(struct blk_plug *plug, bool from_schedule)
+{
+	if (!list_empty(&plug->cb_list))
+		flush_plug_callbacks(plug, from_schedule);
+	blk_mq_flush_plug_list(plug, from_schedule);
+	/*
+	 * Unconditionally flush out cached requests, even if the unplug
+	 * event came from schedule. Since we know hold references to the
+	 * queue for cached requests, we don't want a blocked task holding
+	 * up a queue freeze/quiesce event.
+	 */
+	if (unlikely(!rq_list_empty(plug->cached_rq)))
+		blk_mq_free_plug_rqs(plug);
+}
+
+/**
+ * blk_finish_plug - mark the end of a batch of submitted I/O
+ * @plug:	The &struct blk_plug passed to blk_start_plug()
+ *
+ * Description:
+ * Indicate that a batch of I/O submissions is complete.  This function
+ * must be paired with an initial call to blk_start_plug().  The intent
+ * is to allow the block layer to optimize I/O submission.  See the
+ * documentation for blk_start_plug() for more information.
+ */
+void blk_finish_plug(struct blk_plug *plug)
+{
+	if (plug == current->plug) {
+		__blk_flush_plug(plug, false);
+		current->plug = NULL;
+	}
+}
+EXPORT_SYMBOL(blk_finish_plug);
+
+void blk_io_schedule(void)
+{
+	/* Prevent hang_check timer from firing at us during very long I/O */
+	unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2;
+
+	if (timeout)
+		io_schedule_timeout(timeout);
+	else
+		io_schedule();
+}
+EXPORT_SYMBOL_GPL(blk_io_schedule);
+
+int __init blk_dev_init(void)
+{
+	BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS));
+	BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
+			sizeof_field(struct request, cmd_flags));
+	BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
+			sizeof_field(struct bio, bi_opf));
+	BUILD_BUG_ON(ALIGN(offsetof(struct request_queue, srcu),
+			   __alignof__(struct request_queue)) !=
+		     sizeof(struct request_queue));
+
+	/* used for unplugging and affects IO latency/throughput - HIGHPRI */
+	kblockd_workqueue = alloc_workqueue("kblockd",
+					    WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
+	if (!kblockd_workqueue)
+		panic("Failed to create kblockd\n");
+
+	blk_requestq_cachep = kmem_cache_create("request_queue",
+			sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
+
+	blk_requestq_srcu_cachep = kmem_cache_create("request_queue_srcu",
+			sizeof(struct request_queue) +
+			sizeof(struct srcu_struct), 0, SLAB_PANIC, NULL);
+
+	blk_debugfs_root = debugfs_create_dir("block", NULL);
+
+	return 0;
+}