Merge tag 'block-5.15-2021-09-11' of git://git.kernel.dk/linux-block

Pull block fixes from Jens Axboe:

 - NVMe pull request from Christoph:
     - fix nvmet command set reporting for passthrough controllers (Adam Manzanares)
     - update a MAINTAINERS email address (Chaitanya Kulkarni)
     - set QUEUE_FLAG_NOWAIT for nvme-multipth (me)
     - handle errors from add_disk() (Luis Chamberlain)
     - update the keep alive interval when kato is modified (Tatsuya Sasaki)
     - fix a buffer overrun in nvmet_subsys_attr_serial (Hannes Reinecke)
     - do not reset transport on data digest errors in nvme-tcp (Daniel Wagner)
     - only call synchronize_srcu when clearing current path (Daniel Wagner)
     - revalidate paths during rescan (Hannes Reinecke)

 - Split out the fs/block_dev into block/fops.c and block/bdev.c, which
   has been long overdue. Do this now before -rc1, to avoid annoying
   conflicts due to this (Christoph)

 - blk-throtl use-after-free fix (Li)

 - Improve plug depth for multi-device plugs, greatly increasing md
   resync performance (Song)

 - blkdev_show() locking fix (Tetsuo)

 - n64cart error check fix (Yang)

* tag 'block-5.15-2021-09-11' of git://git.kernel.dk/linux-block:
  n64cart: fix return value check in n64cart_probe()
  blk-mq: allow 4x BLK_MAX_REQUEST_COUNT at blk_plug for multiple_queues
  block: move fs/block_dev.c to block/bdev.c
  block: split out operations on block special files
  blk-throttle: fix UAF by deleteing timer in blk_throtl_exit()
  block: genhd: don't call blkdev_show() with major_names_lock held
  nvme: update MAINTAINERS email address
  nvme: add error handling support for add_disk()
  nvme: only call synchronize_srcu when clearing current path
  nvme: update keep alive interval when kato is modified
  nvme-tcp: Do not reset transport on data digest errors
  nvmet: fixup buffer overrun in nvmet_subsys_attr_serial()
  nvmet: return bool from nvmet_passthru_ctrl and nvmet_is_passthru_req
  nvmet: looks at the passthrough controller when initializing CAP
  nvme: move nvme_multi_css into nvme.h
  nvme-multipath: revalidate paths during rescan
  nvme-multipath: set QUEUE_FLAG_NOWAIT

7 files changed, 1722 insertions, 4 deletions

diff --git a/block/Makefile b/block/Makefile
index 6cf40276d3cf..41aa1ba69c90 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -3,7 +3,7 @@
 # Makefile for the kernel block layer
 #
 
-obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-sysfs.o \
+obj-$(CONFIG_BLOCK) := bdev.o fops.o bio.o elevator.o blk-core.o blk-sysfs.o \
 			blk-flush.o blk-settings.o blk-ioc.o blk-map.o \
 			blk-exec.o blk-merge.o blk-timeout.o \
 			blk-lib.o blk-mq.o blk-mq-tag.o blk-stat.o \
diff --git a/block/bdev.c b/block/bdev.c
new file mode 100644
index 000000000000..cf2780cb44a7
--- /dev/null
+++ b/block/bdev.c
@@ -0,0 +1,1058 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
+ *  Copyright (C) 2016 - 2020 Christoph Hellwig
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/major.h>
+#include <linux/device_cgroup.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/module.h>
+#include <linux/blkpg.h>
+#include <linux/magic.h>
+#include <linux/buffer_head.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+#include <linux/uio.h>
+#include <linux/namei.h>
+#include <linux/cleancache.h>
+#include <linux/part_stat.h>
+#include <linux/uaccess.h>
+#include "../fs/internal.h"
+#include "blk.h"
+
+struct bdev_inode {
+	struct block_device bdev;
+	struct inode vfs_inode;
+};
+
+static inline struct bdev_inode *BDEV_I(struct inode *inode)
+{
+	return container_of(inode, struct bdev_inode, vfs_inode);
+}
+
+struct block_device *I_BDEV(struct inode *inode)
+{
+	return &BDEV_I(inode)->bdev;
+}
+EXPORT_SYMBOL(I_BDEV);
+
+static void bdev_write_inode(struct block_device *bdev)
+{
+	struct inode *inode = bdev->bd_inode;
+	int ret;
+
+	spin_lock(&inode->i_lock);
+	while (inode->i_state & I_DIRTY) {
+		spin_unlock(&inode->i_lock);
+		ret = write_inode_now(inode, true);
+		if (ret) {
+			char name[BDEVNAME_SIZE];
+			pr_warn_ratelimited("VFS: Dirty inode writeback failed "
+					    "for block device %s (err=%d).\n",
+					    bdevname(bdev, name), ret);
+		}
+		spin_lock(&inode->i_lock);
+	}
+	spin_unlock(&inode->i_lock);
+}
+
+/* Kill _all_ buffers and pagecache , dirty or not.. */
+static void kill_bdev(struct block_device *bdev)
+{
+	struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+	if (mapping_empty(mapping))
+		return;
+
+	invalidate_bh_lrus();
+	truncate_inode_pages(mapping, 0);
+}
+
+/* Invalidate clean unused buffers and pagecache. */
+void invalidate_bdev(struct block_device *bdev)
+{
+	struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+	if (mapping->nrpages) {
+		invalidate_bh_lrus();
+		lru_add_drain_all();	/* make sure all lru add caches are flushed */
+		invalidate_mapping_pages(mapping, 0, -1);
+	}
+	/* 99% of the time, we don't need to flush the cleancache on the bdev.
+	 * But, for the strange corners, lets be cautious
+	 */
+	cleancache_invalidate_inode(mapping);
+}
+EXPORT_SYMBOL(invalidate_bdev);
+
+/*
+ * Drop all buffers & page cache for given bdev range. This function bails
+ * with error if bdev has other exclusive owner (such as filesystem).
+ */
+int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
+			loff_t lstart, loff_t lend)
+{
+	/*
+	 * If we don't hold exclusive handle for the device, upgrade to it
+	 * while we discard the buffer cache to avoid discarding buffers
+	 * under live filesystem.
+	 */
+	if (!(mode & FMODE_EXCL)) {
+		int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
+		if (err)
+			goto invalidate;
+	}
+
+	truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
+	if (!(mode & FMODE_EXCL))
+		bd_abort_claiming(bdev, truncate_bdev_range);
+	return 0;
+
+invalidate:
+	/*
+	 * Someone else has handle exclusively open. Try invalidating instead.
+	 * The 'end' argument is inclusive so the rounding is safe.
+	 */
+	return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping,
+					     lstart >> PAGE_SHIFT,
+					     lend >> PAGE_SHIFT);
+}
+
+static void set_init_blocksize(struct block_device *bdev)
+{
+	unsigned int bsize = bdev_logical_block_size(bdev);
+	loff_t size = i_size_read(bdev->bd_inode);
+
+	while (bsize < PAGE_SIZE) {
+		if (size & bsize)
+			break;
+		bsize <<= 1;
+	}
+	bdev->bd_inode->i_blkbits = blksize_bits(bsize);
+}
+
+int set_blocksize(struct block_device *bdev, int size)
+{
+	/* Size must be a power of two, and between 512 and PAGE_SIZE */
+	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
+		return -EINVAL;
+
+	/* Size cannot be smaller than the size supported by the device */
+	if (size < bdev_logical_block_size(bdev))
+		return -EINVAL;
+
+	/* Don't change the size if it is same as current */
+	if (bdev->bd_inode->i_blkbits != blksize_bits(size)) {
+		sync_blockdev(bdev);
+		bdev->bd_inode->i_blkbits = blksize_bits(size);
+		kill_bdev(bdev);
+	}
+	return 0;
+}
+
+EXPORT_SYMBOL(set_blocksize);
+
+int sb_set_blocksize(struct super_block *sb, int size)
+{
+	if (set_blocksize(sb->s_bdev, size))
+		return 0;
+	/* If we get here, we know size is power of two
+	 * and it's value is between 512 and PAGE_SIZE */
+	sb->s_blocksize = size;
+	sb->s_blocksize_bits = blksize_bits(size);
+	return sb->s_blocksize;
+}
+
+EXPORT_SYMBOL(sb_set_blocksize);
+
+int sb_min_blocksize(struct super_block *sb, int size)
+{
+	int minsize = bdev_logical_block_size(sb->s_bdev);
+	if (size < minsize)
+		size = minsize;
+	return sb_set_blocksize(sb, size);
+}
+
+EXPORT_SYMBOL(sb_min_blocksize);
+
+int __sync_blockdev(struct block_device *bdev, int wait)
+{
+	if (!bdev)
+		return 0;
+	if (!wait)
+		return filemap_flush(bdev->bd_inode->i_mapping);
+	return filemap_write_and_wait(bdev->bd_inode->i_mapping);
+}
+
+/*
+ * Write out and wait upon all the dirty data associated with a block
+ * device via its mapping.  Does not take the superblock lock.
+ */
+int sync_blockdev(struct block_device *bdev)
+{
+	return __sync_blockdev(bdev, 1);
+}
+EXPORT_SYMBOL(sync_blockdev);
+
+/*
+ * Write out and wait upon all dirty data associated with this
+ * device.   Filesystem data as well as the underlying block
+ * device.  Takes the superblock lock.
+ */
+int fsync_bdev(struct block_device *bdev)
+{
+	struct super_block *sb = get_super(bdev);
+	if (sb) {
+		int res = sync_filesystem(sb);
+		drop_super(sb);
+		return res;
+	}
+	return sync_blockdev(bdev);
+}
+EXPORT_SYMBOL(fsync_bdev);
+
+/**
+ * freeze_bdev  --  lock a filesystem and force it into a consistent state
+ * @bdev:	blockdevice to lock
+ *
+ * If a superblock is found on this device, we take the s_umount semaphore
+ * on it to make sure nobody unmounts until the snapshot creation is done.
+ * The reference counter (bd_fsfreeze_count) guarantees that only the last
+ * unfreeze process can unfreeze the frozen filesystem actually when multiple
+ * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
+ * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
+ * actually.
+ */
+int freeze_bdev(struct block_device *bdev)
+{
+	struct super_block *sb;
+	int error = 0;
+
+	mutex_lock(&bdev->bd_fsfreeze_mutex);
+	if (++bdev->bd_fsfreeze_count > 1)
+		goto done;
+
+	sb = get_active_super(bdev);
+	if (!sb)
+		goto sync;
+	if (sb->s_op->freeze_super)
+		error = sb->s_op->freeze_super(sb);
+	else
+		error = freeze_super(sb);
+	deactivate_super(sb);
+
+	if (error) {
+		bdev->bd_fsfreeze_count--;
+		goto done;
+	}
+	bdev->bd_fsfreeze_sb = sb;
+
+sync:
+	sync_blockdev(bdev);
+done:
+	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+	return error;
+}
+EXPORT_SYMBOL(freeze_bdev);
+
+/**
+ * thaw_bdev  -- unlock filesystem
+ * @bdev:	blockdevice to unlock
+ *
+ * Unlocks the filesystem and marks it writeable again after freeze_bdev().
+ */
+int thaw_bdev(struct block_device *bdev)
+{
+	struct super_block *sb;
+	int error = -EINVAL;
+
+	mutex_lock(&bdev->bd_fsfreeze_mutex);
+	if (!bdev->bd_fsfreeze_count)
+		goto out;
+
+	error = 0;
+	if (--bdev->bd_fsfreeze_count > 0)
+		goto out;
+
+	sb = bdev->bd_fsfreeze_sb;
+	if (!sb)
+		goto out;
+
+	if (sb->s_op->thaw_super)
+		error = sb->s_op->thaw_super(sb);
+	else
+		error = thaw_super(sb);
+	if (error)
+		bdev->bd_fsfreeze_count++;
+	else
+		bdev->bd_fsfreeze_sb = NULL;
+out:
+	mutex_unlock(&bdev->bd_fsfreeze_mutex);
+	return error;
+}
+EXPORT_SYMBOL(thaw_bdev);
+
+/**
+ * bdev_read_page() - Start reading a page from a block device
+ * @bdev: The device to read the page from
+ * @sector: The offset on the device to read the page to (need not be aligned)
+ * @page: The page to read
+ *
+ * On entry, the page should be locked.  It will be unlocked when the page
+ * has been read.  If the block driver implements rw_page synchronously,
+ * that will be true on exit from this function, but it need not be.
+ *
+ * Errors returned by this function are usually "soft", eg out of memory, or
+ * queue full; callers should try a different route to read this page rather
+ * than propagate an error back up the stack.
+ *
+ * Return: negative errno if an error occurs, 0 if submission was successful.
+ */
+int bdev_read_page(struct block_device *bdev, sector_t sector,
+			struct page *page)
+{
+	const struct block_device_operations *ops = bdev->bd_disk->fops;
+	int result = -EOPNOTSUPP;
+
+	if (!ops->rw_page || bdev_get_integrity(bdev))
+		return result;
+
+	result = blk_queue_enter(bdev->bd_disk->queue, 0);
+	if (result)
+		return result;
+	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
+			      REQ_OP_READ);
+	blk_queue_exit(bdev->bd_disk->queue);
+	return result;
+}
+
+/**
+ * bdev_write_page() - Start writing a page to a block device
+ * @bdev: The device to write the page to
+ * @sector: The offset on the device to write the page to (need not be aligned)
+ * @page: The page to write
+ * @wbc: The writeback_control for the write
+ *
+ * On entry, the page should be locked and not currently under writeback.
+ * On exit, if the write started successfully, the page will be unlocked and
+ * under writeback.  If the write failed already (eg the driver failed to
+ * queue the page to the device), the page will still be locked.  If the
+ * caller is a ->writepage implementation, it will need to unlock the page.
+ *
+ * Errors returned by this function are usually "soft", eg out of memory, or
+ * queue full; callers should try a different route to write this page rather
+ * than propagate an error back up the stack.
+ *
+ * Return: negative errno if an error occurs, 0 if submission was successful.
+ */
+int bdev_write_page(struct block_device *bdev, sector_t sector,
+			struct page *page, struct writeback_control *wbc)
+{
+	int result;
+	const struct block_device_operations *ops = bdev->bd_disk->fops;
+
+	if (!ops->rw_page || bdev_get_integrity(bdev))
+		return -EOPNOTSUPP;
+	result = blk_queue_enter(bdev->bd_disk->queue, 0);
+	if (result)
+		return result;
+
+	set_page_writeback(page);
+	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
+			      REQ_OP_WRITE);
+	if (result) {
+		end_page_writeback(page);
+	} else {
+		clean_page_buffers(page);
+		unlock_page(page);
+	}
+	blk_queue_exit(bdev->bd_disk->queue);
+	return result;
+}
+
+/*
+ * pseudo-fs
+ */
+
+static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
+static struct kmem_cache * bdev_cachep __read_mostly;
+
+static struct inode *bdev_alloc_inode(struct super_block *sb)
+{
+	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
+
+	if (!ei)
+		return NULL;
+	memset(&ei->bdev, 0, sizeof(ei->bdev));
+	return &ei->vfs_inode;
+}
+
+static void bdev_free_inode(struct inode *inode)
+{
+	struct block_device *bdev = I_BDEV(inode);
+
+	free_percpu(bdev->bd_stats);
+	kfree(bdev->bd_meta_info);
+
+	if (!bdev_is_partition(bdev)) {
+		if (bdev->bd_disk && bdev->bd_disk->bdi)
+			bdi_put(bdev->bd_disk->bdi);
+		kfree(bdev->bd_disk);
+	}
+
+	if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
+		blk_free_ext_minor(MINOR(bdev->bd_dev));
+
+	kmem_cache_free(bdev_cachep, BDEV_I(inode));
+}
+
+static void init_once(void *data)
+{
+	struct bdev_inode *ei = data;
+
+	inode_init_once(&ei->vfs_inode);
+}
+
+static void bdev_evict_inode(struct inode *inode)
+{
+	truncate_inode_pages_final(&inode->i_data);
+	invalidate_inode_buffers(inode); /* is it needed here? */
+	clear_inode(inode);
+}
+
+static const struct super_operations bdev_sops = {
+	.statfs = simple_statfs,
+	.alloc_inode = bdev_alloc_inode,
+	.free_inode = bdev_free_inode,
+	.drop_inode = generic_delete_inode,
+	.evict_inode = bdev_evict_inode,
+};
+
+static int bd_init_fs_context(struct fs_context *fc)
+{
+	struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
+	if (!ctx)
+		return -ENOMEM;
+	fc->s_iflags |= SB_I_CGROUPWB;
+	ctx->ops = &bdev_sops;
+	return 0;
+}
+
+static struct file_system_type bd_type = {
+	.name		= "bdev",
+	.init_fs_context = bd_init_fs_context,
+	.kill_sb	= kill_anon_super,
+};
+
+struct super_block *blockdev_superblock __read_mostly;
+EXPORT_SYMBOL_GPL(blockdev_superblock);
+
+void __init bdev_cache_init(void)
+{
+	int err;
+	static struct vfsmount *bd_mnt;
+
+	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
+			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
+				SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
+			init_once);
+	err = register_filesystem(&bd_type);
+	if (err)
+		panic("Cannot register bdev pseudo-fs");
+	bd_mnt = kern_mount(&bd_type);
+	if (IS_ERR(bd_mnt))
+		panic("Cannot create bdev pseudo-fs");
+	blockdev_superblock = bd_mnt->mnt_sb;   /* For writeback */
+}
+
+struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+
+	inode = new_inode(blockdev_superblock);
+	if (!inode)
+		return NULL;
+	inode->i_mode = S_IFBLK;
+	inode->i_rdev = 0;
+	inode->i_data.a_ops = &def_blk_aops;
+	mapping_set_gfp_mask(&inode->i_data, GFP_USER);
+
+	bdev = I_BDEV(inode);
+	mutex_init(&bdev->bd_fsfreeze_mutex);
+	spin_lock_init(&bdev->bd_size_lock);
+	bdev->bd_disk = disk;
+	bdev->bd_partno = partno;
+	bdev->bd_inode = inode;
+	bdev->bd_stats = alloc_percpu(struct disk_stats);
+	if (!bdev->bd_stats) {
+		iput(inode);
+		return NULL;
+	}
+	return bdev;
+}
+
+void bdev_add(struct block_device *bdev, dev_t dev)
+{
+	bdev->bd_dev = dev;
+	bdev->bd_inode->i_rdev = dev;
+	bdev->bd_inode->i_ino = dev;
+	insert_inode_hash(bdev->bd_inode);
+}
+
+long nr_blockdev_pages(void)
+{
+	struct inode *inode;
+	long ret = 0;
+
+	spin_lock(&blockdev_superblock->s_inode_list_lock);
+	list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list)
+		ret += inode->i_mapping->nrpages;
+	spin_unlock(&blockdev_superblock->s_inode_list_lock);
+
+	return ret;
+}
+
+/**
+ * bd_may_claim - test whether a block device can be claimed
+ * @bdev: block device of interest
+ * @whole: whole block device containing @bdev, may equal @bdev
+ * @holder: holder trying to claim @bdev
+ *
+ * Test whether @bdev can be claimed by @holder.
+ *
+ * CONTEXT:
+ * spin_lock(&bdev_lock).
+ *
+ * RETURNS:
+ * %true if @bdev can be claimed, %false otherwise.
+ */
+static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
+			 void *holder)
+{
+	if (bdev->bd_holder == holder)
+		return true;	 /* already a holder */
+	else if (bdev->bd_holder != NULL)
+		return false; 	 /* held by someone else */
+	else if (whole == bdev)
+		return true;  	 /* is a whole device which isn't held */
+
+	else if (whole->bd_holder == bd_may_claim)
+		return true; 	 /* is a partition of a device that is being partitioned */
+	else if (whole->bd_holder != NULL)
+		return false;	 /* is a partition of a held device */
+	else
+		return true;	 /* is a partition of an un-held device */
+}
+
+/**
+ * bd_prepare_to_claim - claim a block device
+ * @bdev: block device of interest
+ * @holder: holder trying to claim @bdev
+ *
+ * Claim @bdev.  This function fails if @bdev is already claimed by another
+ * holder and waits if another claiming is in progress. return, the caller
+ * has ownership of bd_claiming and bd_holder[s].
+ *
+ * RETURNS:
+ * 0 if @bdev can be claimed, -EBUSY otherwise.
+ */
+int bd_prepare_to_claim(struct block_device *bdev, void *holder)
+{
+	struct block_device *whole = bdev_whole(bdev);
+
+	if (WARN_ON_ONCE(!holder))
+		return -EINVAL;
+retry:
+	spin_lock(&bdev_lock);
+	/* if someone else claimed, fail */
+	if (!bd_may_claim(bdev, whole, holder)) {
+		spin_unlock(&bdev_lock);
+		return -EBUSY;
+	}
+
+	/* if claiming is already in progress, wait for it to finish */
+	if (whole->bd_claiming) {
+		wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
+		DEFINE_WAIT(wait);
+
+		prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
+		spin_unlock(&bdev_lock);
+		schedule();
+		finish_wait(wq, &wait);
+		goto retry;
+	}
+
+	/* yay, all mine */
+	whole->bd_claiming = holder;
+	spin_unlock(&bdev_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */
+
+static void bd_clear_claiming(struct block_device *whole, void *holder)
+{
+	lockdep_assert_held(&bdev_lock);
+	/* tell others that we're done */
+	BUG_ON(whole->bd_claiming != holder);
+	whole->bd_claiming = NULL;
+	wake_up_bit(&whole->bd_claiming, 0);
+}
+
+/**
+ * bd_finish_claiming - finish claiming of a block device
+ * @bdev: block device of interest
+ * @holder: holder that has claimed @bdev
+ *
+ * Finish exclusive open of a block device. Mark the device as exlusively
+ * open by the holder and wake up all waiters for exclusive open to finish.
+ */
+static void bd_finish_claiming(struct block_device *bdev, void *holder)
+{
+	struct block_device *whole = bdev_whole(bdev);
+
+	spin_lock(&bdev_lock);
+	BUG_ON(!bd_may_claim(bdev, whole, holder));
+	/*
+	 * Note that for a whole device bd_holders will be incremented twice,
+	 * and bd_holder will be set to bd_may_claim before being set to holder
+	 */
+	whole->bd_holders++;
+	whole->bd_holder = bd_may_claim;
+	bdev->bd_holders++;
+	bdev->bd_holder = holder;
+	bd_clear_claiming(whole, holder);
+	spin_unlock(&bdev_lock);
+}
+
+/**
+ * bd_abort_claiming - abort claiming of a block device
+ * @bdev: block device of interest
+ * @holder: holder that has claimed @bdev
+ *
+ * Abort claiming of a block device when the exclusive open failed. This can be
+ * also used when exclusive open is not actually desired and we just needed
+ * to block other exclusive openers for a while.
+ */
+void bd_abort_claiming(struct block_device *bdev, void *holder)
+{
+	spin_lock(&bdev_lock);
+	bd_clear_claiming(bdev_whole(bdev), holder);
+	spin_unlock(&bdev_lock);
+}
+EXPORT_SYMBOL(bd_abort_claiming);
+
+static void blkdev_flush_mapping(struct block_device *bdev)
+{
+	WARN_ON_ONCE(bdev->bd_holders);
+	sync_blockdev(bdev);
+	kill_bdev(bdev);
+	bdev_write_inode(bdev);
+}
+
+static int blkdev_get_whole(struct block_device *bdev, fmode_t mode)
+{
+	struct gendisk *disk = bdev->bd_disk;
+	int ret = 0;
+
+	if (disk->fops->open) {
+		ret = disk->fops->open(bdev, mode);
+		if (ret) {
+			/* avoid ghost partitions on a removed medium */
+			if (ret == -ENOMEDIUM &&
+			     test_bit(GD_NEED_PART_SCAN, &disk->state))
+				bdev_disk_changed(disk, true);
+			return ret;
+		}
+	}
+
+	if (!bdev->bd_openers)
+		set_init_blocksize(bdev);
+	if (test_bit(GD_NEED_PART_SCAN, &disk->state))
+		bdev_disk_changed(disk, false);
+	bdev->bd_openers++;
+	return 0;;
+}
+
+static void blkdev_put_whole(struct block_device *bdev, fmode_t mode)
+{
+	if (!--bdev->bd_openers)
+		blkdev_flush_mapping(bdev);
+	if (bdev->bd_disk->fops->release)
+		bdev->bd_disk->fops->release(bdev->bd_disk, mode);
+}
+
+static int blkdev_get_part(struct block_device *part, fmode_t mode)
+{
+	struct gendisk *disk = part->bd_disk;
+	int ret;
+
+	if (part->bd_openers)
+		goto done;
+
+	ret = blkdev_get_whole(bdev_whole(part), mode);
+	if (ret)
+		return ret;
+
+	ret = -ENXIO;
+	if (!bdev_nr_sectors(part))
+		goto out_blkdev_put;
+
+	disk->open_partitions++;
+	set_init_blocksize(part);
+done:
+	part->bd_openers++;
+	return 0;
+
+out_blkdev_put:
+	blkdev_put_whole(bdev_whole(part), mode);
+	return ret;
+}
+
+static void blkdev_put_part(struct block_device *part, fmode_t mode)
+{
+	struct block_device *whole = bdev_whole(part);
+
+	if (--part->bd_openers)
+		return;
+	blkdev_flush_mapping(part);
+	whole->bd_disk->open_partitions--;
+	blkdev_put_whole(whole, mode);
+}
+
+struct block_device *blkdev_get_no_open(dev_t dev)
+{
+	struct block_device *bdev;
+	struct inode *inode;
+
+	inode = ilookup(blockdev_superblock, dev);
+	if (!inode) {
+		blk_request_module(dev);
+		inode = ilookup(blockdev_superblock, dev);
+		if (!inode)
+			return NULL;
+	}
+
+	/* switch from the inode reference to a device mode one: */
+	bdev = &BDEV_I(inode)->bdev;
+	if (!kobject_get_unless_zero(&bdev->bd_device.kobj))
+		bdev = NULL;
+	iput(inode);
+
+	if (!bdev)
+		return NULL;
+	if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN) ||
+	    !try_module_get(bdev->bd_disk->fops->owner)) {
+		put_device(&bdev->bd_device);
+		return NULL;
+	}
+
+	return bdev;
+}
+
+void blkdev_put_no_open(struct block_device *bdev)
+{
+	module_put(bdev->bd_disk->fops->owner);
+	put_device(&bdev->bd_device);
+}
+
+/**
+ * blkdev_get_by_dev - open a block device by device number
+ * @dev: device number of block device to open
+ * @mode: FMODE_* mask
+ * @holder: exclusive holder identifier
+ *
+ * Open the block device described by device number @dev. If @mode includes
+ * %FMODE_EXCL, the block device is opened with exclusive access.  Specifying
+ * %FMODE_EXCL with a %NULL @holder is invalid.  Exclusive opens may nest for
+ * the same @holder.
+ *
+ * Use this interface ONLY if you really do not have anything better - i.e. when
+ * you are behind a truly sucky interface and all you are given is a device
+ * number.  Everything else should use blkdev_get_by_path().
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * Reference to the block_device on success, ERR_PTR(-errno) on failure.
+ */
+struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
+{
+	bool unblock_events = true;
+	struct block_device *bdev;
+	struct gendisk *disk;
+	int ret;
+
+	ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
+			MAJOR(dev), MINOR(dev),
+			((mode & FMODE_READ) ? DEVCG_ACC_READ : 0) |
+			((mode & FMODE_WRITE) ? DEVCG_ACC_WRITE : 0));
+	if (ret)
+		return ERR_PTR(ret);
+
+	bdev = blkdev_get_no_open(dev);
+	if (!bdev)
+		return ERR_PTR(-ENXIO);
+	disk = bdev->bd_disk;
+
+	if (mode & FMODE_EXCL) {
+		ret = bd_prepare_to_claim(bdev, holder);
+		if (ret)
+			goto put_blkdev;
+	}
+
+	disk_block_events(disk);
+
+	mutex_lock(&disk->open_mutex);
+	ret = -ENXIO;
+	if (!disk_live(disk))
+		goto abort_claiming;
+	if (bdev_is_partition(bdev))
+		ret = blkdev_get_part(bdev, mode);
+	else
+		ret = blkdev_get_whole(bdev, mode);
+	if (ret)
+		goto abort_claiming;
+	if (mode & FMODE_EXCL) {
+		bd_finish_claiming(bdev, holder);
+
+		/*
+		 * Block event polling for write claims if requested.  Any write
+		 * holder makes the write_holder state stick until all are
+		 * released.  This is good enough and tracking individual
+		 * writeable reference is too fragile given the way @mode is
+		 * used in blkdev_get/put().
+		 */
+		if ((mode & FMODE_WRITE) && !bdev->bd_write_holder &&
+		    (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
+			bdev->bd_write_holder = true;
+			unblock_events = false;
+		}
+	}
+	mutex_unlock(&disk->open_mutex);
+
+	if (unblock_events)
+		disk_unblock_events(disk);
+	return bdev;
+
+abort_claiming:
+	if (mode & FMODE_EXCL)
+		bd_abort_claiming(bdev, holder);
+	mutex_unlock(&disk->open_mutex);
+	disk_unblock_events(disk);
+put_blkdev:
+	blkdev_put_no_open(bdev);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(blkdev_get_by_dev);
+
+/**
+ * blkdev_get_by_path - open a block device by name
+ * @path: path to the block device to open
+ * @mode: FMODE_* mask
+ * @holder: exclusive holder identifier
+ *
+ * Open the block device described by the device file at @path.  If @mode
+ * includes %FMODE_EXCL, the block device is opened with exclusive access.
+ * Specifying %FMODE_EXCL with a %NULL @holder is invalid.  Exclusive opens may
+ * nest for the same @holder.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * Reference to the block_device on success, ERR_PTR(-errno) on failure.
+ */
+struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
+					void *holder)
+{
+	struct block_device *bdev;
+	dev_t dev;
+	int error;
+
+	error = lookup_bdev(path, &dev);
+	if (error)
+		return ERR_PTR(error);
+
+	bdev = blkdev_get_by_dev(dev, mode, holder);
+	if (!IS_ERR(bdev) && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
+		blkdev_put(bdev, mode);
+		return ERR_PTR(-EACCES);
+	}
+
+	return bdev;
+}
+EXPORT_SYMBOL(blkdev_get_by_path);
+
+void blkdev_put(struct block_device *bdev, fmode_t mode)
+{
+	struct gendisk *disk = bdev->bd_disk;
+
+	/*
+	 * Sync early if it looks like we're the last one.  If someone else
+	 * opens the block device between now and the decrement of bd_openers
+	 * then we did a sync that we didn't need to, but that's not the end
+	 * of the world and we want to avoid long (could be several minute)
+	 * syncs while holding the mutex.
+	 */
+	if (bdev->bd_openers == 1)
+		sync_blockdev(bdev);
+
+	mutex_lock(&disk->open_mutex);
+	if (mode & FMODE_EXCL) {
+		struct block_device *whole = bdev_whole(bdev);
+		bool bdev_free;
+
+		/*
+		 * Release a claim on the device.  The holder fields
+		 * are protected with bdev_lock.  open_mutex is to
+		 * synchronize disk_holder unlinking.
+		 */
+		spin_lock(&bdev_lock);
+
+		WARN_ON_ONCE(--bdev->bd_holders < 0);
+		WARN_ON_ONCE(--whole->bd_holders < 0);
+
+		if ((bdev_free = !bdev->bd_holders))
+			bdev->bd_holder = NULL;
+		if (!whole->bd_holders)
+			whole->bd_holder = NULL;
+
+		spin_unlock(&bdev_lock);
+
+		/*
+		 * If this was the last claim, remove holder link and
+		 * unblock evpoll if it was a write holder.
+		 */
+		if (bdev_free && bdev->bd_write_holder) {
+			disk_unblock_events(disk);
+			bdev->bd_write_holder = false;
+		}
+	}
+
+	/*
+	 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
+	 * event.  This is to ensure detection of media removal commanded
+	 * from userland - e.g. eject(1).
+	 */
+	disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE);
+
+	if (bdev_is_partition(bdev))
+		blkdev_put_part(bdev, mode);
+	else
+		blkdev_put_whole(bdev, mode);
+	mutex_unlock(&disk->open_mutex);
+
+	blkdev_put_no_open(bdev);
+}
+EXPORT_SYMBOL(blkdev_put);
+
+/**
+ * lookup_bdev  - lookup a struct block_device by name
+ * @pathname:	special file representing the block device
+ * @dev:	return value of the block device's dev_t
+ *
+ * Get a reference to the blockdevice at @pathname in the current
+ * namespace if possible and return it.  Return ERR_PTR(error)
+ * otherwise.
+ */
+int lookup_bdev(const char *pathname, dev_t *dev)
+{
+	struct inode *inode;
+	struct path path;
+	int error;
+
+	if (!pathname || !*pathname)
+		return -EINVAL;
+
+	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
+	if (error)
+		return error;
+
+	inode = d_backing_inode(path.dentry);
+	error = -ENOTBLK;
+	if (!S_ISBLK(inode->i_mode))
+		goto out_path_put;
+	error = -EACCES;
+	if (!may_open_dev(&path))
+		goto out_path_put;
+
+	*dev = inode->i_rdev;
+	error = 0;
+out_path_put:
+	path_put(&path);
+	return error;
+}
+EXPORT_SYMBOL(lookup_bdev);
+
+int __invalidate_device(struct block_device *bdev, bool kill_dirty)
+{
+	struct super_block *sb = get_super(bdev);
+	int res = 0;
+
+	if (sb) {
+		/*
+		 * no need to lock the super, get_super holds the
+		 * read mutex so the filesystem cannot go away
+		 * under us (->put_super runs with the write lock
+		 * hold).
+		 */
+		shrink_dcache_sb(sb);
+		res = invalidate_inodes(sb, kill_dirty);
+		drop_super(sb);
+	}
+	invalidate_bdev(bdev);
+	return res;
+}
+EXPORT_SYMBOL(__invalidate_device);
+
+void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
+{
+	struct inode *inode, *old_inode = NULL;
+
+	spin_lock(&blockdev_superblock->s_inode_list_lock);
+	list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
+		struct address_space *mapping = inode->i_mapping;
+		struct block_device *bdev;
+
+		spin_lock(&inode->i_lock);
+		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
+		    mapping->nrpages == 0) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&blockdev_superblock->s_inode_list_lock);
+		/*
+		 * We hold a reference to 'inode' so it couldn't have been
+		 * removed from s_inodes list while we dropped the
+		 * s_inode_list_lock  We cannot iput the inode now as we can
+		 * be holding the last reference and we cannot iput it under
+		 * s_inode_list_lock. So we keep the reference and iput it
+		 * later.
+		 */
+		iput(old_inode);
+		old_inode = inode;
+		bdev = I_BDEV(inode);
+
+		mutex_lock(&bdev->bd_disk->open_mutex);
+		if (bdev->bd_openers)
+			func(bdev, arg);
+		mutex_unlock(&bdev->bd_disk->open_mutex);
+
+		spin_lock(&blockdev_superblock->s_inode_list_lock);
+	}
+	spin_unlock(&blockdev_superblock->s_inode_list_lock);
+	iput(old_inode);
+}
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 65d3a63aecc6..108a352051be 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2135,6 +2135,18 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
 	}
 }
 
+/*
+ * Allow 4x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
+ * queues. This is important for md arrays to benefit from merging
+ * requests.
+ */
+static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
+{
+	if (plug->multiple_queues)
+		return BLK_MAX_REQUEST_COUNT * 4;
+	return BLK_MAX_REQUEST_COUNT;
+}
+
 /**
  * blk_mq_submit_bio - Create and send a request to block device.
  * @bio: Bio pointer.
@@ -2231,7 +2243,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
 		else
 			last = list_entry_rq(plug->mq_list.prev);
 
-		if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
+		if (request_count >= blk_plug_max_rq_count(plug) || (last &&
 		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
 			blk_flush_plug_list(plug, false);
 			trace_block_plug(q);
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 55c49015e533..7c4e7993ba97 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2458,6 +2458,7 @@ int blk_throtl_init(struct request_queue *q)
 void blk_throtl_exit(struct request_queue *q)
 {
 	BUG_ON(!q->td);
+	del_timer_sync(&q->td->service_queue.pending_timer);
 	throtl_shutdown_wq(q);
 	blkcg_deactivate_policy(q, &blkcg_policy_throtl);
 	free_percpu(q->td->latency_buckets[READ]);
diff --git a/block/blk.h b/block/blk.h
index 8c96b0c90c48..7d2a0ba7ed21 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -373,4 +373,6 @@ static inline void bio_clear_hipri(struct bio *bio)
 	bio->bi_opf &= ~REQ_HIPRI;
 }
 
+extern const struct address_space_operations def_blk_aops;
+
 #endif /* BLK_INTERNAL_H */
diff --git a/block/fops.c b/block/fops.c
new file mode 100644
index 000000000000..ffce6f6c68dd
--- /dev/null
+++ b/block/fops.c
@@ -0,0 +1,640 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 1991, 1992  Linus Torvalds
+ * Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
+ * Copyright (C) 2016 - 2020 Christoph Hellwig
+ */
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include <linux/uio.h>
+#include <linux/namei.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/falloc.h>
+#include <linux/suspend.h>
+#include "blk.h"
+
+static struct inode *bdev_file_inode(struct file *file)
+{
+	return file->f_mapping->host;
+}
+
+static int blkdev_get_block(struct inode *inode, sector_t iblock,
+		struct buffer_head *bh, int create)
+{
+	bh->b_bdev = I_BDEV(inode);
+	bh->b_blocknr = iblock;
+	set_buffer_mapped(bh);
+	return 0;
+}
+
+static unsigned int dio_bio_write_op(struct kiocb *iocb)
+{
+	unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
+
+	/* avoid the need for a I/O completion work item */
+	if (iocb->ki_flags & IOCB_DSYNC)
+		op |= REQ_FUA;
+	return op;
+}
+
+#define DIO_INLINE_BIO_VECS 4
+
+static void blkdev_bio_end_io_simple(struct bio *bio)
+{
+	struct task_struct *waiter = bio->bi_private;
+
+	WRITE_ONCE(bio->bi_private, NULL);
+	blk_wake_io_task(waiter);
+}
+
+static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
+		struct iov_iter *iter, unsigned int nr_pages)
+{
+	struct file *file = iocb->ki_filp;
+	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
+	struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
+	loff_t pos = iocb->ki_pos;
+	bool should_dirty = false;
+	struct bio bio;
+	ssize_t ret;
+	blk_qc_t qc;
+
+	if ((pos | iov_iter_alignment(iter)) &
+	    (bdev_logical_block_size(bdev) - 1))
+		return -EINVAL;
+
+	if (nr_pages <= DIO_INLINE_BIO_VECS)
+		vecs = inline_vecs;
+	else {
+		vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
+				     GFP_KERNEL);
+		if (!vecs)
+			return -ENOMEM;
+	}
+
+	bio_init(&bio, vecs, nr_pages);
+	bio_set_dev(&bio, bdev);
+	bio.bi_iter.bi_sector = pos >> 9;
+	bio.bi_write_hint = iocb->ki_hint;
+	bio.bi_private = current;
+	bio.bi_end_io = blkdev_bio_end_io_simple;
+	bio.bi_ioprio = iocb->ki_ioprio;
+
+	ret = bio_iov_iter_get_pages(&bio, iter);
+	if (unlikely(ret))
+		goto out;
+	ret = bio.bi_iter.bi_size;
+
+	if (iov_iter_rw(iter) == READ) {
+		bio.bi_opf = REQ_OP_READ;
+		if (iter_is_iovec(iter))
+			should_dirty = true;
+	} else {
+		bio.bi_opf = dio_bio_write_op(iocb);
+		task_io_account_write(ret);
+	}
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		bio.bi_opf |= REQ_NOWAIT;
+	if (iocb->ki_flags & IOCB_HIPRI)
+		bio_set_polled(&bio, iocb);
+
+	qc = submit_bio(&bio);
+	for (;;) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (!READ_ONCE(bio.bi_private))
+			break;
+		if (!(iocb->ki_flags & IOCB_HIPRI) ||
+		    !blk_poll(bdev_get_queue(bdev), qc, true))
+			blk_io_schedule();
+	}
+	__set_current_state(TASK_RUNNING);
+
+	bio_release_pages(&bio, should_dirty);
+	if (unlikely(bio.bi_status))
+		ret = blk_status_to_errno(bio.bi_status);
+
+out:
+	if (vecs != inline_vecs)
+		kfree(vecs);
+
+	bio_uninit(&bio);
+
+	return ret;
+}
+
+struct blkdev_dio {
+	union {
+		struct kiocb		*iocb;
+		struct task_struct	*waiter;
+	};
+	size_t			size;
+	atomic_t		ref;
+	bool			multi_bio : 1;
+	bool			should_dirty : 1;
+	bool			is_sync : 1;
+	struct bio		bio;
+};
+
+static struct bio_set blkdev_dio_pool;
+
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+}
+
+static void blkdev_bio_end_io(struct bio *bio)
+{
+	struct blkdev_dio *dio = bio->bi_private;
+	bool should_dirty = dio->should_dirty;
+
+	if (bio->bi_status && !dio->bio.bi_status)
+		dio->bio.bi_status = bio->bi_status;
+
+	if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) {
+		if (!dio->is_sync) {
+			struct kiocb *iocb = dio->iocb;
+			ssize_t ret;
+
+			if (likely(!dio->bio.bi_status)) {
+				ret = dio->size;
+				iocb->ki_pos += ret;
+			} else {
+				ret = blk_status_to_errno(dio->bio.bi_status);
+			}
+
+			dio->iocb->ki_complete(iocb, ret, 0);
+			if (dio->multi_bio)
+				bio_put(&dio->bio);
+		} else {
+			struct task_struct *waiter = dio->waiter;
+
+			WRITE_ONCE(dio->waiter, NULL);
+			blk_wake_io_task(waiter);
+		}
+	}
+
+	if (should_dirty) {
+		bio_check_pages_dirty(bio);
+	} else {
+		bio_release_pages(bio, false);
+		bio_put(bio);
+	}
+}
+
+static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
+		unsigned int nr_pages)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = bdev_file_inode(file);
+	struct block_device *bdev = I_BDEV(inode);
+	struct blk_plug plug;
+	struct blkdev_dio *dio;
+	struct bio *bio;
+	bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
+	bool is_read = (iov_iter_rw(iter) == READ), is_sync;
+	loff_t pos = iocb->ki_pos;
+	blk_qc_t qc = BLK_QC_T_NONE;
+	int ret = 0;
+
+	if ((pos | iov_iter_alignment(iter)) &
+	    (bdev_logical_block_size(bdev) - 1))
+		return -EINVAL;
+
+	bio = bio_alloc_kiocb(iocb, nr_pages, &blkdev_dio_pool);
+
+	dio = container_of(bio, struct blkdev_dio, bio);
+	dio->is_sync = is_sync = is_sync_kiocb(iocb);
+	if (dio->is_sync) {
+		dio->waiter = current;
+		bio_get(bio);
+	} else {
+		dio->iocb = iocb;
+	}
+
+	dio->size = 0;
+	dio->multi_bio = false;
+	dio->should_dirty = is_read && iter_is_iovec(iter);
+
+	/*
+	 * Don't plug for HIPRI/polled IO, as those should go straight
+	 * to issue
+	 */
+	if (!is_poll)
+		blk_start_plug(&plug);
+
+	for (;;) {
+		bio_set_dev(bio, bdev);
+		bio->bi_iter.bi_sector = pos >> 9;
+		bio->bi_write_hint = iocb->ki_hint;
+		bio->bi_private = dio;
+		bio->bi_end_io = blkdev_bio_end_io;
+		bio->bi_ioprio = iocb->ki_ioprio;
+
+		ret = bio_iov_iter_get_pages(bio, iter);
+		if (unlikely(ret)) {
+			bio->bi_status = BLK_STS_IOERR;
+			bio_endio(bio);
+			break;
+		}
+
+		if (is_read) {
+			bio->bi_opf = REQ_OP_READ;
+			if (dio->should_dirty)
+				bio_set_pages_dirty(bio);
+		} else {
+			bio->bi_opf = dio_bio_write_op(iocb);
+			task_io_account_write(bio->bi_iter.bi_size);
+		}
+		if (iocb->ki_flags & IOCB_NOWAIT)
+			bio->bi_opf |= REQ_NOWAIT;
+
+		dio->size += bio->bi_iter.bi_size;
+		pos += bio->bi_iter.bi_size;
+
+		nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
+		if (!nr_pages) {
+			bool polled = false;
+
+			if (iocb->ki_flags & IOCB_HIPRI) {
+				bio_set_polled(bio, iocb);
+				polled = true;
+			}
+
+			qc = submit_bio(bio);
+
+			if (polled)
+				WRITE_ONCE(iocb->ki_cookie, qc);
+			break;
+		}
+
+		if (!dio->multi_bio) {
+			/*
+			 * AIO needs an extra reference to ensure the dio
+			 * structure which is embedded into the first bio
+			 * stays around.
+			 */
+			if (!is_sync)
+				bio_get(bio);
+			dio->multi_bio = true;
+			atomic_set(&dio->ref, 2);
+		} else {
+			atomic_inc(&dio->ref);
+		}
+
+		submit_bio(bio);
+		bio = bio_alloc(GFP_KERNEL, nr_pages);
+	}
+
+	if (!is_poll)
+		blk_finish_plug(&plug);
+
+	if (!is_sync)
+		return -EIOCBQUEUED;
+
+	for (;;) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (!READ_ONCE(dio->waiter))
+			break;
+
+		if (!(iocb->ki_flags & IOCB_HIPRI) ||
+		    !blk_poll(bdev_get_queue(bdev), qc, true))
+			blk_io_schedule();
+	}
+	__set_current_state(TASK_RUNNING);
+
+	if (!ret)
+		ret = blk_status_to_errno(dio->bio.bi_status);
+	if (likely(!ret))
+		ret = dio->size;
+
+	bio_put(&dio->bio);
+	return ret;
+}
+
+static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
+{
+	unsigned int nr_pages;
+
+	if (!iov_iter_count(iter))
+		return 0;
+
+	nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
+	if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_VECS)
+		return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
+
+	return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
+}
+
+static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, blkdev_get_block, wbc);
+}
+
+static int blkdev_readpage(struct file * file, struct page * page)
+{
+	return block_read_full_page(page, blkdev_get_block);
+}
+
+static void blkdev_readahead(struct readahead_control *rac)
+{
+	mpage_readahead(rac, blkdev_get_block);
+}
+
+static int blkdev_write_begin(struct file *file, struct address_space *mapping,
+		loff_t pos, unsigned len, unsigned flags, struct page **pagep,
+		void **fsdata)
+{
+	return block_write_begin(mapping, pos, len, flags, pagep,
+				 blkdev_get_block);
+}
+
+static int blkdev_write_end(struct file *file, struct address_space *mapping,
+		loff_t pos, unsigned len, unsigned copied, struct page *page,
+		void *fsdata)
+{
+	int ret;
+	ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+	unlock_page(page);
+	put_page(page);
+
+	return ret;
+}
+
+static int blkdev_writepages(struct address_space *mapping,
+			     struct writeback_control *wbc)
+{
+	return generic_writepages(mapping, wbc);
+}
+
+const struct address_space_operations def_blk_aops = {
+	.set_page_dirty	= __set_page_dirty_buffers,
+	.readpage	= blkdev_readpage,
+	.readahead	= blkdev_readahead,
+	.writepage	= blkdev_writepage,
+	.write_begin	= blkdev_write_begin,
+	.write_end	= blkdev_write_end,
+	.writepages	= blkdev_writepages,
+	.direct_IO	= blkdev_direct_IO,
+	.migratepage	= buffer_migrate_page_norefs,
+	.is_dirty_writeback = buffer_check_dirty_writeback,
+};
+
+/*
+ * for a block special file file_inode(file)->i_size is zero
+ * so we compute the size by hand (just as in block_read/write above)
+ */
+static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *bd_inode = bdev_file_inode(file);
+	loff_t retval;
+
+	inode_lock(bd_inode);
+	retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
+	inode_unlock(bd_inode);
+	return retval;
+}
+
+static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
+		int datasync)
+{
+	struct inode *bd_inode = bdev_file_inode(filp);
+	struct block_device *bdev = I_BDEV(bd_inode);
+	int error;
+
+	error = file_write_and_wait_range(filp, start, end);
+	if (error)
+		return error;
+
+	/*
+	 * There is no need to serialise calls to blkdev_issue_flush with
+	 * i_mutex and doing so causes performance issues with concurrent
+	 * O_SYNC writers to a block device.
+	 */
+	error = blkdev_issue_flush(bdev);
+	if (error == -EOPNOTSUPP)
+		error = 0;
+
+	return error;
+}
+
+static int blkdev_open(struct inode *inode, struct file *filp)
+{
+	struct block_device *bdev;
+
+	/*
+	 * Preserve backwards compatibility and allow large file access
+	 * even if userspace doesn't ask for it explicitly. Some mkfs
+	 * binary needs it. We might want to drop this workaround
+	 * during an unstable branch.
+	 */
+	filp->f_flags |= O_LARGEFILE;
+	filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
+
+	if (filp->f_flags & O_NDELAY)
+		filp->f_mode |= FMODE_NDELAY;
+	if (filp->f_flags & O_EXCL)
+		filp->f_mode |= FMODE_EXCL;
+	if ((filp->f_flags & O_ACCMODE) == 3)
+		filp->f_mode |= FMODE_WRITE_IOCTL;
+
+	bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);
+	if (IS_ERR(bdev))
+		return PTR_ERR(bdev);
+	filp->f_mapping = bdev->bd_inode->i_mapping;
+	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
+	return 0;
+}
+
+static int blkdev_close(struct inode *inode, struct file *filp)
+{
+	struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
+
+	blkdev_put(bdev, filp->f_mode);
+	return 0;
+}
+
+static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
+{
+	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
+	fmode_t mode = file->f_mode;
+
+	/*
+	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
+	 * to updated it before every ioctl.
+	 */
+	if (file->f_flags & O_NDELAY)
+		mode |= FMODE_NDELAY;
+	else
+		mode &= ~FMODE_NDELAY;
+
+	return blkdev_ioctl(bdev, mode, cmd, arg);
+}
+
+/*
+ * Write data to the block device.  Only intended for the block device itself
+ * and the raw driver which basically is a fake block device.
+ *
+ * Does not take i_mutex for the write and thus is not for general purpose
+ * use.
+ */
+static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *bd_inode = bdev_file_inode(file);
+	loff_t size = i_size_read(bd_inode);
+	struct blk_plug plug;
+	size_t shorted = 0;
+	ssize_t ret;
+
+	if (bdev_read_only(I_BDEV(bd_inode)))
+		return -EPERM;
+
+	if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
+		return -ETXTBSY;
+
+	if (!iov_iter_count(from))
+		return 0;
+
+	if (iocb->ki_pos >= size)
+		return -ENOSPC;
+
+	if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
+		return -EOPNOTSUPP;
+
+	size -= iocb->ki_pos;
+	if (iov_iter_count(from) > size) {
+		shorted = iov_iter_count(from) - size;
+		iov_iter_truncate(from, size);
+	}
+
+	blk_start_plug(&plug);
+	ret = __generic_file_write_iter(iocb, from);
+	if (ret > 0)
+		ret = generic_write_sync(iocb, ret);
+	iov_iter_reexpand(from, iov_iter_count(from) + shorted);
+	blk_finish_plug(&plug);
+	return ret;
+}
+
+static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *bd_inode = bdev_file_inode(file);
+	loff_t size = i_size_read(bd_inode);
+	loff_t pos = iocb->ki_pos;
+	size_t shorted = 0;
+	ssize_t ret;
+
+	if (pos >= size)
+		return 0;
+
+	size -= pos;
+	if (iov_iter_count(to) > size) {
+		shorted = iov_iter_count(to) - size;
+		iov_iter_truncate(to, size);
+	}
+
+	ret = generic_file_read_iter(iocb, to);
+	iov_iter_reexpand(to, iov_iter_count(to) + shorted);
+	return ret;
+}
+
+#define	BLKDEV_FALLOC_FL_SUPPORTED					\
+		(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |		\
+		 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
+
+static long blkdev_fallocate(struct file *file, int mode, loff_t start,
+			     loff_t len)
+{
+	struct block_device *bdev = I_BDEV(bdev_file_inode(file));
+	loff_t end = start + len - 1;
+	loff_t isize;
+	int error;
+
+	/* Fail if we don't recognize the flags. */
+	if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
+		return -EOPNOTSUPP;
+
+	/* Don't go off the end of the device. */
+	isize = i_size_read(bdev->bd_inode);
+	if (start >= isize)
+		return -EINVAL;
+	if (end >= isize) {
+		if (mode & FALLOC_FL_KEEP_SIZE) {
+			len = isize - start;
+			end = start + len - 1;
+		} else
+			return -EINVAL;
+	}
+
+	/*
+	 * Don't allow IO that isn't aligned to logical block size.
+	 */
+	if ((start | len) & (bdev_logical_block_size(bdev) - 1))
+		return -EINVAL;
+
+	/* Invalidate the page cache, including dirty pages. */
+	error = truncate_bdev_range(bdev, file->f_mode, start, end);
+	if (error)
+		return error;
+
+	switch (mode) {
+	case FALLOC_FL_ZERO_RANGE:
+	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
+		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
+					    GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
+		break;
+	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
+		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
+					     GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
+		break;
+	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
+		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
+					     GFP_KERNEL, 0);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+	if (error)
+		return error;
+
+	/*
+	 * Invalidate the page cache again; if someone wandered in and dirtied
+	 * a page, we just discard it - userspace has no way of knowing whether
+	 * the write happened before or after discard completing...
+	 */
+	return truncate_bdev_range(bdev, file->f_mode, start, end);
+}
+
+const struct file_operations def_blk_fops = {
+	.open		= blkdev_open,
+	.release	= blkdev_close,
+	.llseek		= blkdev_llseek,
+	.read_iter	= blkdev_read_iter,
+	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
+	.mmap		= generic_file_mmap,
+	.fsync		= blkdev_fsync,
+	.unlocked_ioctl	= block_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= compat_blkdev_ioctl,
+#endif
+	.splice_read	= generic_file_splice_read,
+	.splice_write	= iter_file_splice_write,
+	.fallocate	= blkdev_fallocate,
+};
+
+static __init int blkdev_init(void)
+{
+	return bioset_init(&blkdev_dio_pool, 4,
+				offsetof(struct blkdev_dio, bio),
+				BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
+}
+module_init(blkdev_init);
diff --git a/block/genhd.c b/block/genhd.c
index 567549a011d1..7b6e5e1cf956 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -183,6 +183,7 @@ static struct blk_major_name {
 	void (*probe)(dev_t devt);
 } *major_names[BLKDEV_MAJOR_HASH_SIZE];
 static DEFINE_MUTEX(major_names_lock);
+static DEFINE_SPINLOCK(major_names_spinlock);
 
 /* index in the above - for now: assume no multimajor ranges */
 static inline int major_to_index(unsigned major)
@@ -195,11 +196,11 @@ void blkdev_show(struct seq_file *seqf, off_t offset)
 {
 	struct blk_major_name *dp;
 
-	mutex_lock(&major_names_lock);
+	spin_lock(&major_names_spinlock);
 	for (dp = major_names[major_to_index(offset)]; dp; dp = dp->next)
 		if (dp->major == offset)
 			seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
-	mutex_unlock(&major_names_lock);
+	spin_unlock(&major_names_spinlock);
 }
 #endif /* CONFIG_PROC_FS */
 
@@ -271,6 +272,7 @@ int __register_blkdev(unsigned int major, const char *name,
 	p->next = NULL;
 	index = major_to_index(major);
 
+	spin_lock(&major_names_spinlock);
 	for (n = &major_names[index]; *n; n = &(*n)->next) {
 		if ((*n)->major == major)
 			break;
@@ -279,6 +281,7 @@ int __register_blkdev(unsigned int major, const char *name,
 		*n = p;
 	else
 		ret = -EBUSY;
+	spin_unlock(&major_names_spinlock);
 
 	if (ret < 0) {
 		printk("register_blkdev: cannot get major %u for %s\n",
@@ -298,6 +301,7 @@ void unregister_blkdev(unsigned int major, const char *name)
 	int index = major_to_index(major);
 
 	mutex_lock(&major_names_lock);
+	spin_lock(&major_names_spinlock);
 	for (n = &major_names[index]; *n; n = &(*n)->next)
 		if ((*n)->major == major)
 			break;
@@ -307,6 +311,7 @@ void unregister_blkdev(unsigned int major, const char *name)
 		p = *n;
 		*n = p->next;
 	}
+	spin_unlock(&major_names_spinlock);
 	mutex_unlock(&major_names_lock);
 	kfree(p);
 }