Merge tag 'for-5.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs updates from David Sterba:
 "The updates this time are more under the hood and enhancing existing
  features (subpage with compression and zoned namespaces).

  Performance related:

   - misc small inode logging improvements (+3% throughput, -11% latency
     on sample dbench workload)

   - more efficient directory logging: bulk item insertion, less tree
     searches and locking

   - speed up bulk insertion of items into a b-tree, which is used when
     logging directories, when running delayed items for directories
     (fsync and transaction commits) and when running the slow path
     (full sync) of an fsync (bulk creation run time -4%, deletion -12%)

  Core:

   - continued subpage support
      - make defragmentation work
      - make compression write work

   - zoned mode
      - support ZNS (zoned namespaces), zone capacity is number of
        usable blocks in each zone
      - add dedicated block group (zoned) for relocation, to prevent
        out of order writes in some cases
      - greedy block group reclaim, pick the ones with least usable
        space first

   - preparatory work for send protocol updates

   - error handling improvements

   - cleanups and refactoring

  Fixes:

   - lockdep warnings
      - in show_devname callback, on seeding device
      - device delete on loop device due to conversions to workqueues

   - fix deadlock between chunk allocation and chunk btree modifications

   - fix tracking of missing device count and status"

* tag 'for-5.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (140 commits)
  btrfs: remove root argument from check_item_in_log()
  btrfs: remove root argument from add_link()
  btrfs: remove root argument from btrfs_unlink_inode()
  btrfs: remove root argument from drop_one_dir_item()
  btrfs: clear MISSING device status bit in btrfs_close_one_device
  btrfs: call btrfs_check_rw_degradable only if there is a missing device
  btrfs: send: prepare for v2 protocol
  btrfs: fix comment about sector sizes supported in 64K systems
  btrfs: update device path inode time instead of bd_inode
  fs: export an inode_update_time helper
  btrfs: fix deadlock when defragging transparent huge pages
  btrfs: sysfs: convert scnprintf and snprintf to sysfs_emit
  btrfs: make btrfs_super_block size match BTRFS_SUPER_INFO_SIZE
  btrfs: update comments for chunk allocation -ENOSPC cases
  btrfs: fix deadlock between chunk allocation and chunk btree modifications
  btrfs: zoned: use greedy gc for auto reclaim
  btrfs: check-integrity: stop storing the block device name in btrfsic_dev_state
  btrfs: use btrfs_get_dev_args_from_path in dev removal ioctls
  btrfs: add a btrfs_get_dev_args_from_path helper
  btrfs: handle device lookup with btrfs_dev_lookup_args
  ...

1 files changed, 336 insertions, 256 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9533f358850e..61ac57bcbf1a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -14,6 +14,7 @@
 #include <linux/semaphore.h>
 #include <linux/uuid.h>
 #include <linux/list_sort.h>
+#include <linux/namei.h>
 #include "misc.h"
 #include "ctree.h"
 #include "extent_map.h"
@@ -250,7 +251,7 @@ static void btrfs_dev_stat_print_on_load(struct btrfs_device *device);
 static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 			     enum btrfs_map_op op,
 			     u64 logical, u64 *length,
-			     struct btrfs_bio **bbio_ret,
+			     struct btrfs_io_context **bioc_ret,
 			     int mirror_num, int need_raid_map);
 
 /*
@@ -812,9 +813,13 @@ static noinline struct btrfs_device *device_list_add(const char *path,
 
 		device = NULL;
 	} else {
+		struct btrfs_dev_lookup_args args = {
+			.devid = devid,
+			.uuid = disk_super->dev_item.uuid,
+		};
+
 		mutex_lock(&fs_devices->device_list_mutex);
-		device = btrfs_find_device(fs_devices, devid,
-				disk_super->dev_item.uuid, NULL);
+		device = btrfs_find_device(fs_devices, &args);
 
 		/*
 		 * If this disk has been pulled into an fs devices created by
@@ -1091,7 +1096,7 @@ void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices)
 	list_for_each_entry(seed_dev, &fs_devices->seed_list, seed_list)
 		__btrfs_free_extra_devids(seed_dev, &latest_dev);
 
-	fs_devices->latest_bdev = latest_dev->bdev;
+	fs_devices->latest_dev = latest_dev;
 
 	mutex_unlock(&uuid_mutex);
 }
@@ -1122,8 +1127,10 @@ static void btrfs_close_one_device(struct btrfs_device *device)
 	if (device->devid == BTRFS_DEV_REPLACE_DEVID)
 		clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
 
-	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
+	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
+		clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state);
 		fs_devices->missing_devices--;
+	}
 
 	btrfs_close_bdev(device);
 	if (device->bdev) {
@@ -1222,7 +1229,7 @@ static int open_fs_devices(struct btrfs_fs_devices *fs_devices,
 		return -EINVAL;
 
 	fs_devices->opened = 1;
-	fs_devices->latest_bdev = latest_dev->bdev;
+	fs_devices->latest_dev = latest_dev;
 	fs_devices->total_rw_bytes = 0;
 	fs_devices->chunk_alloc_policy = BTRFS_CHUNK_ALLOC_REGULAR;
 	fs_devices->read_policy = BTRFS_READ_POLICY_PID;
@@ -1843,8 +1850,10 @@ static int btrfs_add_dev_item(struct btrfs_trans_handle *trans,
 	key.type = BTRFS_DEV_ITEM_KEY;
 	key.offset = device->devid;
 
+	btrfs_reserve_chunk_metadata(trans, true);
 	ret = btrfs_insert_empty_item(trans, trans->fs_info->chunk_root, path,
 				      &key, sizeof(*dev_item));
+	btrfs_trans_release_chunk_metadata(trans);
 	if (ret)
 		goto out;
 
@@ -1882,18 +1891,22 @@ out:
 /*
  * Function to update ctime/mtime for a given device path.
  * Mainly used for ctime/mtime based probe like libblkid.
+ *
+ * We don't care about errors here, this is just to be kind to userspace.
  */
-static void update_dev_time(struct block_device *bdev)
+static void update_dev_time(const char *device_path)
 {
-	struct inode *inode = bdev->bd_inode;
+	struct path path;
 	struct timespec64 now;
+	int ret;
 
-	/* Shouldn't happen but just in case. */
-	if (!inode)
+	ret = kern_path(device_path, LOOKUP_FOLLOW, &path);
+	if (ret)
 		return;
 
-	now = current_time(inode);
-	generic_update_time(inode, &now, S_MTIME | S_CTIME);
+	now = current_time(d_inode(path.dentry));
+	inode_update_time(d_inode(path.dentry), &now, S_MTIME | S_CTIME);
+	path_put(&path);
 }
 
 static int btrfs_rm_dev_item(struct btrfs_device *device)
@@ -1917,7 +1930,9 @@ static int btrfs_rm_dev_item(struct btrfs_device *device)
 	key.type = BTRFS_DEV_ITEM_KEY;
 	key.offset = device->devid;
 
+	btrfs_reserve_chunk_metadata(trans, false);
 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+	btrfs_trans_release_chunk_metadata(trans);
 	if (ret) {
 		if (ret > 0)
 			ret = -ENOENT;
@@ -1986,7 +2001,7 @@ static struct btrfs_device * btrfs_find_next_active_device(
 }
 
 /*
- * Helper function to check if the given device is part of s_bdev / latest_bdev
+ * Helper function to check if the given device is part of s_bdev / latest_dev
  * and replace it with the provided or the next active device, in the context
  * where this function called, there should be always be another device (or
  * this_dev) which is active.
@@ -2005,8 +2020,8 @@ void __cold btrfs_assign_next_active_device(struct btrfs_device *device,
 			(fs_info->sb->s_bdev == device->bdev))
 		fs_info->sb->s_bdev = next_device->bdev;
 
-	if (fs_info->fs_devices->latest_bdev == device->bdev)
-		fs_info->fs_devices->latest_bdev = next_device->bdev;
+	if (fs_info->fs_devices->latest_dev->bdev == device->bdev)
+		fs_info->fs_devices->latest_dev = next_device;
 }
 
 /*
@@ -2069,11 +2084,12 @@ void btrfs_scratch_superblocks(struct btrfs_fs_info *fs_info,
 	btrfs_kobject_uevent(bdev, KOBJ_CHANGE);
 
 	/* Update ctime/mtime for device path for libblkid */
-	update_dev_time(bdev);
+	update_dev_time(device_path);
 }
 
-int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
-		    u64 devid, struct block_device **bdev, fmode_t *mode)
+int btrfs_rm_device(struct btrfs_fs_info *fs_info,
+		    struct btrfs_dev_lookup_args *args,
+		    struct block_device **bdev, fmode_t *mode)
 {
 	struct btrfs_device *device;
 	struct btrfs_fs_devices *cur_devices;
@@ -2081,22 +2097,23 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	u64 num_devices;
 	int ret = 0;
 
-	mutex_lock(&uuid_mutex);
-
+	/*
+	 * The device list in fs_devices is accessed without locks (neither
+	 * uuid_mutex nor device_list_mutex) as it won't change on a mounted
+	 * filesystem and another device rm cannot run.
+	 */
 	num_devices = btrfs_num_devices(fs_info);
 
 	ret = btrfs_check_raid_min_devices(fs_info, num_devices - 1);
 	if (ret)
 		goto out;
 
-	device = btrfs_find_device_by_devspec(fs_info, devid, device_path);
-
-	if (IS_ERR(device)) {
-		if (PTR_ERR(device) == -ENOENT &&
-		    device_path && strcmp(device_path, "missing") == 0)
+	device = btrfs_find_device(fs_info->fs_devices, args);
+	if (!device) {
+		if (args->missing)
 			ret = BTRFS_ERROR_DEV_MISSING_NOT_FOUND;
 		else
-			ret = PTR_ERR(device);
+			ret = -ENOENT;
 		goto out;
 	}
 
@@ -2126,11 +2143,9 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 		mutex_unlock(&fs_info->chunk_mutex);
 	}
 
-	mutex_unlock(&uuid_mutex);
 	ret = btrfs_shrink_device(device, 0);
 	if (!ret)
 		btrfs_reada_remove_dev(device);
-	mutex_lock(&uuid_mutex);
 	if (ret)
 		goto error_undo;
 
@@ -2159,7 +2174,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	/*
 	 * In normal cases the cur_devices == fs_devices. But in case
 	 * of deleting a seed device, the cur_devices should point to
-	 * its own fs_devices listed under the fs_devices->seed.
+	 * its own fs_devices listed under the fs_devices->seed_list.
 	 */
 	cur_devices = device->fs_devices;
 	mutex_lock(&fs_devices->device_list_mutex);
@@ -2210,14 +2225,21 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	synchronize_rcu();
 	btrfs_free_device(device);
 
-	if (cur_devices->open_devices == 0) {
+	/*
+	 * This can happen if cur_devices is the private seed devices list.  We
+	 * cannot call close_fs_devices() here because it expects the uuid_mutex
+	 * to be held, but in fact we don't need that for the private
+	 * seed_devices, we can simply decrement cur_devices->opened and then
+	 * remove it from our list and free the fs_devices.
+	 */
+	if (cur_devices->num_devices == 0) {
 		list_del_init(&cur_devices->seed_list);
-		close_fs_devices(cur_devices);
+		ASSERT(cur_devices->opened == 1);
+		cur_devices->opened--;
 		free_fs_devices(cur_devices);
 	}
 
 out:
-	mutex_unlock(&uuid_mutex);
 	return ret;
 
 error_undo:
@@ -2305,13 +2327,6 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
 
 	mutex_unlock(&fs_devices->device_list_mutex);
 
-	/*
-	 * The update_dev_time() with in btrfs_scratch_superblocks()
-	 * may lead to a call to btrfs_show_devname() which will try
-	 * to hold device_list_mutex. And here this device
-	 * is already out of device list, so we don't have to hold
-	 * the device_list_mutex lock.
-	 */
 	btrfs_scratch_superblocks(tgtdev->fs_info, tgtdev->bdev,
 				  tgtdev->name->str);
 
@@ -2320,69 +2335,98 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
 	btrfs_free_device(tgtdev);
 }
 
-static struct btrfs_device *btrfs_find_device_by_path(
-		struct btrfs_fs_info *fs_info, const char *device_path)
+/**
+ * Populate args from device at path
+ *
+ * @fs_info:	the filesystem
+ * @args:	the args to populate
+ * @path:	the path to the device
+ *
+ * This will read the super block of the device at @path and populate @args with
+ * the devid, fsid, and uuid.  This is meant to be used for ioctls that need to
+ * lookup a device to operate on, but need to do it before we take any locks.
+ * This properly handles the special case of "missing" that a user may pass in,
+ * and does some basic sanity checks.  The caller must make sure that @path is
+ * properly NUL terminated before calling in, and must call
+ * btrfs_put_dev_args_from_path() in order to free up the temporary fsid and
+ * uuid buffers.
+ *
+ * Return: 0 for success, -errno for failure
+ */
+int btrfs_get_dev_args_from_path(struct btrfs_fs_info *fs_info,
+				 struct btrfs_dev_lookup_args *args,
+				 const char *path)
 {
-	int ret = 0;
 	struct btrfs_super_block *disk_super;
-	u64 devid;
-	u8 *dev_uuid;
 	struct block_device *bdev;
-	struct btrfs_device *device;
+	int ret;
 
-	ret = btrfs_get_bdev_and_sb(device_path, FMODE_READ,
-				    fs_info->bdev_holder, 0, &bdev, &disk_super);
-	if (ret)
-		return ERR_PTR(ret);
+	if (!path || !path[0])
+		return -EINVAL;
+	if (!strcmp(path, "missing")) {
+		args->missing = true;
+		return 0;
+	}
 
-	devid = btrfs_stack_device_id(&disk_super->dev_item);
-	dev_uuid = disk_super->dev_item.uuid;
+	args->uuid = kzalloc(BTRFS_UUID_SIZE, GFP_KERNEL);
+	args->fsid = kzalloc(BTRFS_FSID_SIZE, GFP_KERNEL);
+	if (!args->uuid || !args->fsid) {
+		btrfs_put_dev_args_from_path(args);
+		return -ENOMEM;
+	}
+
+	ret = btrfs_get_bdev_and_sb(path, FMODE_READ, fs_info->bdev_holder, 0,
+				    &bdev, &disk_super);
+	if (ret)
+		return ret;
+	args->devid = btrfs_stack_device_id(&disk_super->dev_item);
+	memcpy(args->uuid, disk_super->dev_item.uuid, BTRFS_UUID_SIZE);
 	if (btrfs_fs_incompat(fs_info, METADATA_UUID))
-		device = btrfs_find_device(fs_info->fs_devices, devid, dev_uuid,
-					   disk_super->metadata_uuid);
+		memcpy(args->fsid, disk_super->metadata_uuid, BTRFS_FSID_SIZE);
 	else
-		device = btrfs_find_device(fs_info->fs_devices, devid, dev_uuid,
-					   disk_super->fsid);
-
+		memcpy(args->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
 	btrfs_release_disk_super(disk_super);
-	if (!device)
-		device = ERR_PTR(-ENOENT);
 	blkdev_put(bdev, FMODE_READ);
-	return device;
+	return 0;
 }
 
 /*
- * Lookup a device given by device id, or the path if the id is 0.
+ * Only use this jointly with btrfs_get_dev_args_from_path() because we will
+ * allocate our ->uuid and ->fsid pointers, everybody else uses local variables
+ * that don't need to be freed.
  */
+void btrfs_put_dev_args_from_path(struct btrfs_dev_lookup_args *args)
+{
+	kfree(args->uuid);
+	kfree(args->fsid);
+	args->uuid = NULL;
+	args->fsid = NULL;
+}
+
 struct btrfs_device *btrfs_find_device_by_devspec(
 		struct btrfs_fs_info *fs_info, u64 devid,
 		const char *device_path)
 {
+	BTRFS_DEV_LOOKUP_ARGS(args);
 	struct btrfs_device *device;
+	int ret;
 
 	if (devid) {
-		device = btrfs_find_device(fs_info->fs_devices, devid, NULL,
-					   NULL);
+		args.devid = devid;
+		device = btrfs_find_device(fs_info->fs_devices, &args);
 		if (!device)
 			return ERR_PTR(-ENOENT);
 		return device;
 	}
 
-	if (!device_path || !device_path[0])
-		return ERR_PTR(-EINVAL);
-
-	if (strcmp(device_path, "missing") == 0) {
-		/* Find first missing device */
-		list_for_each_entry(device, &fs_info->fs_devices->devices,
-				    dev_list) {
-			if (test_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
-				     &device->dev_state) && !device->bdev)
-				return device;
-		}
+	ret = btrfs_get_dev_args_from_path(fs_info, &args, device_path);
+	if (ret)
+		return ERR_PTR(ret);
+	device = btrfs_find_device(fs_info->fs_devices, &args);
+	btrfs_put_dev_args_from_path(&args);
+	if (!device)
 		return ERR_PTR(-ENOENT);
-	}
-
-	return btrfs_find_device_by_path(fs_info, device_path);
+	return device;
 }
 
 /*
@@ -2459,6 +2503,7 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
  */
 static int btrfs_finish_sprout(struct btrfs_trans_handle *trans)
 {
+	BTRFS_DEV_LOOKUP_ARGS(args);
 	struct btrfs_fs_info *fs_info = trans->fs_info;
 	struct btrfs_root *root = fs_info->chunk_root;
 	struct btrfs_path *path;
@@ -2468,7 +2513,6 @@ static int btrfs_finish_sprout(struct btrfs_trans_handle *trans)
 	struct btrfs_key key;
 	u8 fs_uuid[BTRFS_FSID_SIZE];
 	u8 dev_uuid[BTRFS_UUID_SIZE];
-	u64 devid;
 	int ret;
 
 	path = btrfs_alloc_path();
@@ -2480,7 +2524,9 @@ static int btrfs_finish_sprout(struct btrfs_trans_handle *trans)
 	key.type = BTRFS_DEV_ITEM_KEY;
 
 	while (1) {
+		btrfs_reserve_chunk_metadata(trans, false);
 		ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+		btrfs_trans_release_chunk_metadata(trans);
 		if (ret < 0)
 			goto error;
 
@@ -2505,13 +2551,14 @@ next_slot:
 
 		dev_item = btrfs_item_ptr(leaf, path->slots[0],
 					  struct btrfs_dev_item);
-		devid = btrfs_device_id(leaf, dev_item);
+		args.devid = btrfs_device_id(leaf, dev_item);
 		read_extent_buffer(leaf, dev_uuid, btrfs_device_uuid(dev_item),
 				   BTRFS_UUID_SIZE);
 		read_extent_buffer(leaf, fs_uuid, btrfs_device_fsid(dev_item),
 				   BTRFS_FSID_SIZE);
-		device = btrfs_find_device(fs_info->fs_devices, devid, dev_uuid,
-					   fs_uuid);
+		args.uuid = dev_uuid;
+		args.fsid = fs_uuid;
+		device = btrfs_find_device(fs_info->fs_devices, &args);
 		BUG_ON(!device); /* Logic error */
 
 		if (device->fs_devices->seeding) {
@@ -2627,6 +2674,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 			btrfs_abort_transaction(trans, ret);
 			goto error_trans;
 		}
+		btrfs_assign_next_active_device(fs_info->fs_devices->latest_dev,
+						device);
 	}
 
 	device->fs_devices = fs_devices;
@@ -2733,7 +2782,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 	btrfs_forget_devices(device_path);
 
 	/* Update ctime/mtime for blkid or udev */
-	update_dev_time(bdev);
+	update_dev_time(device_path);
 
 	return ret;
 
@@ -2826,6 +2875,7 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 	struct btrfs_super_block *super_copy = fs_info->super_copy;
 	u64 old_total;
 	u64 diff;
+	int ret;
 
 	if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state))
 		return -EACCES;
@@ -2854,7 +2904,11 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
 			      &trans->transaction->dev_update_list);
 	mutex_unlock(&fs_info->chunk_mutex);
 
-	return btrfs_update_device(trans, device);
+	btrfs_reserve_chunk_metadata(trans, false);
+	ret = btrfs_update_device(trans, device);
+	btrfs_trans_release_chunk_metadata(trans);
+
+	return ret;
 }
 
 static int btrfs_free_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
@@ -3096,7 +3150,7 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset)
 		const u64 sys_flags = btrfs_system_alloc_profile(fs_info);
 		struct btrfs_block_group *sys_bg;
 
-		sys_bg = btrfs_alloc_chunk(trans, sys_flags);
+		sys_bg = btrfs_create_chunk(trans, sys_flags);
 		if (IS_ERR(sys_bg)) {
 			ret = PTR_ERR(sys_bg);
 			btrfs_abort_transaction(trans, ret);
@@ -4889,8 +4943,10 @@ again:
 			round_down(old_total - diff, fs_info->sectorsize));
 	mutex_unlock(&fs_info->chunk_mutex);
 
+	btrfs_reserve_chunk_metadata(trans, false);
 	/* Now btrfs_update_device() will change the on-disk size. */
 	ret = btrfs_update_device(trans, device);
+	btrfs_trans_release_chunk_metadata(trans);
 	if (ret < 0) {
 		btrfs_abort_transaction(trans, ret);
 		btrfs_end_transaction(trans);
@@ -4973,7 +5029,7 @@ static void check_raid1c34_incompat_flag(struct btrfs_fs_info *info, u64 type)
 }
 
 /*
- * Structure used internally for __btrfs_alloc_chunk() function.
+ * Structure used internally for btrfs_create_chunk() function.
  * Wraps needed parameters.
  */
 struct alloc_chunk_ctl {
@@ -5377,7 +5433,7 @@ error_del_extent:
 	return block_group;
 }
 
-struct btrfs_block_group *btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
+struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans,
 					    u64 type)
 {
 	struct btrfs_fs_info *info = trans->fs_info;
@@ -5578,12 +5634,12 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans)
 	 */
 
 	alloc_profile = btrfs_metadata_alloc_profile(fs_info);
-	meta_bg = btrfs_alloc_chunk(trans, alloc_profile);
+	meta_bg = btrfs_create_chunk(trans, alloc_profile);
 	if (IS_ERR(meta_bg))
 		return PTR_ERR(meta_bg);
 
 	alloc_profile = btrfs_system_alloc_profile(fs_info);
-	sys_bg = btrfs_alloc_chunk(trans, alloc_profile);
+	sys_bg = btrfs_create_chunk(trans, alloc_profile);
 	if (IS_ERR(sys_bg))
 		return PTR_ERR(sys_bg);
 
@@ -5597,17 +5653,17 @@ static inline int btrfs_chunk_max_errors(struct map_lookup *map)
 	return btrfs_raid_array[index].tolerated_failures;
 }
 
-int btrfs_chunk_readonly(struct btrfs_fs_info *fs_info, u64 chunk_offset)
+bool btrfs_chunk_writeable(struct btrfs_fs_info *fs_info, u64 chunk_offset)
 {
 	struct extent_map *em;
 	struct map_lookup *map;
-	int readonly = 0;
 	int miss_ndevs = 0;
 	int i;
+	bool ret = true;
 
 	em = btrfs_get_chunk_map(fs_info, chunk_offset, 1);
 	if (IS_ERR(em))
-		return 1;
+		return false;
 
 	map = em->map_lookup;
 	for (i = 0; i < map->num_stripes; i++) {
@@ -5618,21 +5674,20 @@ int btrfs_chunk_readonly(struct btrfs_fs_info *fs_info, u64 chunk_offset)
 		}
 		if (!test_bit(BTRFS_DEV_STATE_WRITEABLE,
 					&map->stripes[i].dev->dev_state)) {
-			readonly = 1;
+			ret = false;
 			goto end;
 		}
 	}
 
 	/*
-	 * If the number of missing devices is larger than max errors,
-	 * we can not write the data into that chunk successfully, so
-	 * set it readonly.
+	 * If the number of missing devices is larger than max errors, we can
+	 * not write the data into that chunk successfully.
 	 */
 	if (miss_ndevs > btrfs_chunk_max_errors(map))
-		readonly = 1;
+		ret = false;
 end:
 	free_extent_map(em);
-	return readonly;
+	return ret;
 }
 
 void btrfs_mapping_tree_free(struct extent_map_tree *tree)
@@ -5795,7 +5850,7 @@ static int find_live_mirror(struct btrfs_fs_info *fs_info,
 }
 
 /* Bubble-sort the stripe set to put the parity/syndrome stripes last */
-static void sort_parity_stripes(struct btrfs_bio *bbio, int num_stripes)
+static void sort_parity_stripes(struct btrfs_io_context *bioc, int num_stripes)
 {
 	int i;
 	int again = 1;
@@ -5804,52 +5859,55 @@ static void sort_parity_stripes(struct btrfs_bio *bbio, int num_stripes)
 		again = 0;
 		for (i = 0; i < num_stripes - 1; i++) {
 			/* Swap if parity is on a smaller index */
-			if (bbio->raid_map[i] > bbio->raid_map[i + 1]) {
-				swap(bbio->stripes[i], bbio->stripes[i + 1]);
-				swap(bbio->raid_map[i], bbio->raid_map[i + 1]);
+			if (bioc->raid_map[i] > bioc->raid_map[i + 1]) {
+				swap(bioc->stripes[i], bioc->stripes[i + 1]);
+				swap(bioc->raid_map[i], bioc->raid_map[i + 1]);
 				again = 1;
 			}
 		}
 	}
 }
 
-static struct btrfs_bio *alloc_btrfs_bio(int total_stripes, int real_stripes)
+static struct btrfs_io_context *alloc_btrfs_io_context(struct btrfs_fs_info *fs_info,
+						       int total_stripes,
+						       int real_stripes)
 {
-	struct btrfs_bio *bbio = kzalloc(
-		 /* the size of the btrfs_bio */
-		sizeof(struct btrfs_bio) +
-		/* plus the variable array for the stripes */
-		sizeof(struct btrfs_bio_stripe) * (total_stripes) +
-		/* plus the variable array for the tgt dev */
+	struct btrfs_io_context *bioc = kzalloc(
+		 /* The size of btrfs_io_context */
+		sizeof(struct btrfs_io_context) +
+		/* Plus the variable array for the stripes */
+		sizeof(struct btrfs_io_stripe) * (total_stripes) +
+		/* Plus the variable array for the tgt dev */
 		sizeof(int) * (real_stripes) +
 		/*
-		 * plus the raid_map, which includes both the tgt dev
-		 * and the stripes
+		 * Plus the raid_map, which includes both the tgt dev
+		 * and the stripes.
 		 */
 		sizeof(u64) * (total_stripes),
 		GFP_NOFS|__GFP_NOFAIL);
 
-	atomic_set(&bbio->error, 0);
-	refcount_set(&bbio->refs, 1);
+	atomic_set(&bioc->error, 0);
+	refcount_set(&bioc->refs, 1);
 
-	bbio->tgtdev_map = (int *)(bbio->stripes + total_stripes);
-	bbio->raid_map = (u64 *)(bbio->tgtdev_map + real_stripes);
+	bioc->fs_info = fs_info;
+	bioc->tgtdev_map = (int *)(bioc->stripes + total_stripes);
+	bioc->raid_map = (u64 *)(bioc->tgtdev_map + real_stripes);
 
-	return bbio;
+	return bioc;
 }
 
-void btrfs_get_bbio(struct btrfs_bio *bbio)
+void btrfs_get_bioc(struct btrfs_io_context *bioc)
 {
-	WARN_ON(!refcount_read(&bbio->refs));
-	refcount_inc(&bbio->refs);
+	WARN_ON(!refcount_read(&bioc->refs));
+	refcount_inc(&bioc->refs);
 }
 
-void btrfs_put_bbio(struct btrfs_bio *bbio)
+void btrfs_put_bioc(struct btrfs_io_context *bioc)
 {
-	if (!bbio)
+	if (!bioc)
 		return;
-	if (refcount_dec_and_test(&bbio->refs))
-		kfree(bbio);
+	if (refcount_dec_and_test(&bioc->refs))
+		kfree(bioc);
 }
 
 /* can REQ_OP_DISCARD be sent with other REQ like REQ_OP_WRITE? */
@@ -5859,11 +5917,11 @@ void btrfs_put_bbio(struct btrfs_bio *bbio)
  */
 static int __btrfs_map_block_for_discard(struct btrfs_fs_info *fs_info,
 					 u64 logical, u64 *length_ret,
-					 struct btrfs_bio **bbio_ret)
+					 struct btrfs_io_context **bioc_ret)
 {
 	struct extent_map *em;
 	struct map_lookup *map;
-	struct btrfs_bio *bbio;
+	struct btrfs_io_context *bioc;
 	u64 length = *length_ret;
 	u64 offset;
 	u64 stripe_nr;
@@ -5882,8 +5940,8 @@ static int __btrfs_map_block_for_discard(struct btrfs_fs_info *fs_info,
 	int ret = 0;
 	int i;
 
-	/* discard always return a bbio */
-	ASSERT(bbio_ret);
+	/* Discard always returns a bioc. */
+	ASSERT(bioc_ret);
 
 	em = btrfs_get_chunk_map(fs_info, logical, length);
 	if (IS_ERR(em))
@@ -5946,26 +6004,25 @@ static int __btrfs_map_block_for_discard(struct btrfs_fs_info *fs_info,
 					&stripe_index);
 	}
 
-	bbio = alloc_btrfs_bio(num_stripes, 0);
-	if (!bbio) {
+	bioc = alloc_btrfs_io_context(fs_info, num_stripes, 0);
+	if (!bioc) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
 	for (i = 0; i < num_stripes; i++) {
-		bbio->stripes[i].physical =
+		bioc->stripes[i].physical =
 			map->stripes[stripe_index].physical +
 			stripe_offset + stripe_nr * map->stripe_len;
-		bbio->stripes[i].dev = map->stripes[stripe_index].dev;
+		bioc->stripes[i].dev = map->stripes[stripe_index].dev;
 
 		if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
 				 BTRFS_BLOCK_GROUP_RAID10)) {
-			bbio->stripes[i].length = stripes_per_dev *
+			bioc->stripes[i].length = stripes_per_dev *
 				map->stripe_len;
 
 			if (i / sub_stripes < remaining_stripes)
-				bbio->stripes[i].length +=
-					map->stripe_len;
+				bioc->stripes[i].length += map->stripe_len;
 
 			/*
 			 * Special for the first stripe and
@@ -5976,19 +6033,17 @@ static int __btrfs_map_block_for_discard(struct btrfs_fs_info *fs_info,
 			 *    off     end_off
 			 */
 			if (i < sub_stripes)
-				bbio->stripes[i].length -=
-					stripe_offset;
+				bioc->stripes[i].length -= stripe_offset;
 
 			if (stripe_index >= last_stripe &&
 			    stripe_index <= (last_stripe +
 					     sub_stripes - 1))
-				bbio->stripes[i].length -=
-					stripe_end_offset;
+				bioc->stripes[i].length -= stripe_end_offset;
 
 			if (i == sub_stripes - 1)
 				stripe_offset = 0;
 		} else {
-			bbio->stripes[i].length = length;
+			bioc->stripes[i].length = length;
 		}
 
 		stripe_index++;
@@ -5998,9 +6053,9 @@ static int __btrfs_map_block_for_discard(struct btrfs_fs_info *fs_info,
 		}
 	}
 
-	*bbio_ret = bbio;
-	bbio->map_type = map->type;
-	bbio->num_stripes = num_stripes;
+	*bioc_ret = bioc;
+	bioc->map_type = map->type;
+	bioc->num_stripes = num_stripes;
 out:
 	free_extent_map(em);
 	return ret;
@@ -6024,7 +6079,7 @@ static int get_extra_mirror_from_replace(struct btrfs_fs_info *fs_info,
 					 u64 srcdev_devid, int *mirror_num,
 					 u64 *physical)
 {
-	struct btrfs_bio *bbio = NULL;
+	struct btrfs_io_context *bioc = NULL;
 	int num_stripes;
 	int index_srcdev = 0;
 	int found = 0;
@@ -6033,20 +6088,20 @@ static int get_extra_mirror_from_replace(struct btrfs_fs_info *fs_info,
 	int ret = 0;
 
 	ret = __btrfs_map_block(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
-				logical, &length, &bbio, 0, 0);
+				logical, &length, &bioc, 0, 0);
 	if (ret) {
-		ASSERT(bbio == NULL);
+		ASSERT(bioc == NULL);
 		return ret;
 	}
 
-	num_stripes = bbio->num_stripes;
+	num_stripes = bioc->num_stripes;
 	if (*mirror_num > num_stripes) {
 		/*
 		 * BTRFS_MAP_GET_READ_MIRRORS does not contain this mirror,
 		 * that means that the requested area is not left of the left
 		 * cursor
 		 */
-		btrfs_put_bbio(bbio);
+		btrfs_put_bioc(bioc);
 		return -EIO;
 	}
 
@@ -6056,7 +6111,7 @@ static int get_extra_mirror_from_replace(struct btrfs_fs_info *fs_info,
 	 * pointer to the one of the target drive.
 	 */
 	for (i = 0; i < num_stripes; i++) {
-		if (bbio->stripes[i].dev->devid != srcdev_devid)
+		if (bioc->stripes[i].dev->devid != srcdev_devid)
 			continue;
 
 		/*
@@ -6064,15 +6119,15 @@ static int get_extra_mirror_from_replace(struct btrfs_fs_info *fs_info,
 		 * mirror with the lowest physical address
 		 */
 		if (found &&
-		    physical_of_found <= bbio->stripes[i].physical)
+		    physical_of_found <= bioc->stripes[i].physical)
 			continue;
 
 		index_srcdev = i;
 		found = 1;
-		physical_of_found = bbio->stripes[i].physical;
+		physical_of_found = bioc->stripes[i].physical;
 	}
 
-	btrfs_put_bbio(bbio);
+	btrfs_put_bioc(bioc);
 
 	ASSERT(found);
 	if (!found)
@@ -6103,12 +6158,12 @@ static bool is_block_group_to_copy(struct btrfs_fs_info *fs_info, u64 logical)
 }
 
 static void handle_ops_on_dev_replace(enum btrfs_map_op op,
-				      struct btrfs_bio **bbio_ret,
+				      struct btrfs_io_context **bioc_ret,
 				      struct btrfs_dev_replace *dev_replace,
 				      u64 logical,
 				      int *num_stripes_ret, int *max_errors_ret)
 {
-	struct btrfs_bio *bbio = *bbio_ret;
+	struct btrfs_io_context *bioc = *bioc_ret;
 	u64 srcdev_devid = dev_replace->srcdev->devid;
 	int tgtdev_indexes = 0;
 	int num_stripes = *num_stripes_ret;
@@ -6138,17 +6193,17 @@ static void handle_ops_on_dev_replace(enum btrfs_map_op op,
 		 */
 		index_where_to_add = num_stripes;
 		for (i = 0; i < num_stripes; i++) {
-			if (bbio->stripes[i].dev->devid == srcdev_devid) {
+			if (bioc->stripes[i].dev->devid == srcdev_devid) {
 				/* write to new disk, too */
-				struct btrfs_bio_stripe *new =
-					bbio->stripes + index_where_to_add;
-				struct btrfs_bio_stripe *old =
-					bbio->stripes + i;
+				struct btrfs_io_stripe *new =
+					bioc->stripes + index_where_to_add;
+				struct btrfs_io_stripe *old =
+					bioc->stripes + i;
 
 				new->physical = old->physical;
 				new->length = old->length;
 				new->dev = dev_replace->tgtdev;
-				bbio->tgtdev_map[i] = index_where_to_add;
+				bioc->tgtdev_map[i] = index_where_to_add;
 				index_where_to_add++;
 				max_errors++;
 				tgtdev_indexes++;
@@ -6168,30 +6223,29 @@ static void handle_ops_on_dev_replace(enum btrfs_map_op op,
 		 * full copy of the source drive.
 		 */
 		for (i = 0; i < num_stripes; i++) {
-			if (bbio->stripes[i].dev->devid == srcdev_devid) {
+			if (bioc->stripes[i].dev->devid == srcdev_devid) {
 				/*
 				 * In case of DUP, in order to keep it simple,
 				 * only add the mirror with the lowest physical
 				 * address
 				 */
 				if (found &&
-				    physical_of_found <=
-				     bbio->stripes[i].physical)
+				    physical_of_found <= bioc->stripes[i].physical)
 					continue;
 				index_srcdev = i;
 				found = 1;
-				physical_of_found = bbio->stripes[i].physical;
+				physical_of_found = bioc->stripes[i].physical;
 			}
 		}
 		if (found) {
-			struct btrfs_bio_stripe *tgtdev_stripe =
-				bbio->stripes + num_stripes;
+			struct btrfs_io_stripe *tgtdev_stripe =
+				bioc->stripes + num_stripes;
 
 			tgtdev_stripe->physical = physical_of_found;
 			tgtdev_stripe->length =
-				bbio->stripes[index_srcdev].length;
+				bioc->stripes[index_srcdev].length;
 			tgtdev_stripe->dev = dev_replace->tgtdev;
-			bbio->tgtdev_map[index_srcdev] = num_stripes;
+			bioc->tgtdev_map[index_srcdev] = num_stripes;
 
 			tgtdev_indexes++;
 			num_stripes++;
@@ -6200,8 +6254,8 @@ static void handle_ops_on_dev_replace(enum btrfs_map_op op,
 
 	*num_stripes_ret = num_stripes;
 	*max_errors_ret = max_errors;
-	bbio->num_tgtdevs = tgtdev_indexes;
-	*bbio_ret = bbio;
+	bioc->num_tgtdevs = tgtdev_indexes;
+	*bioc_ret = bioc;
 }
 
 static bool need_full_stripe(enum btrfs_map_op op)
@@ -6304,7 +6358,7 @@ int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, struct extent_map *em,
 static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 			     enum btrfs_map_op op,
 			     u64 logical, u64 *length,
-			     struct btrfs_bio **bbio_ret,
+			     struct btrfs_io_context **bioc_ret,
 			     int mirror_num, int need_raid_map)
 {
 	struct extent_map *em;
@@ -6319,7 +6373,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 	int num_stripes;
 	int max_errors = 0;
 	int tgtdev_indexes = 0;
-	struct btrfs_bio *bbio = NULL;
+	struct btrfs_io_context *bioc = NULL;
 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 	int dev_replace_is_ongoing = 0;
 	int num_alloc_stripes;
@@ -6328,7 +6382,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 	u64 raid56_full_stripe_start = (u64)-1;
 	struct btrfs_io_geometry geom;
 
-	ASSERT(bbio_ret);
+	ASSERT(bioc_ret);
 	ASSERT(op != BTRFS_MAP_DISCARD);
 
 	em = btrfs_get_chunk_map(fs_info, logical, *length);
@@ -6472,20 +6526,20 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 		tgtdev_indexes = num_stripes;
 	}
 
-	bbio = alloc_btrfs_bio(num_alloc_stripes, tgtdev_indexes);
-	if (!bbio) {
+	bioc = alloc_btrfs_io_context(fs_info, num_alloc_stripes, tgtdev_indexes);
+	if (!bioc) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
 	for (i = 0; i < num_stripes; i++) {
-		bbio->stripes[i].physical = map->stripes[stripe_index].physical +
+		bioc->stripes[i].physical = map->stripes[stripe_index].physical +
 			stripe_offset + stripe_nr * map->stripe_len;
-		bbio->stripes[i].dev = map->stripes[stripe_index].dev;
+		bioc->stripes[i].dev = map->stripes[stripe_index].dev;
 		stripe_index++;
 	}
 
-	/* build raid_map */
+	/* Build raid_map */
 	if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK && need_raid_map &&
 	    (need_full_stripe(op) || mirror_num > 1)) {
 		u64 tmp;
@@ -6497,15 +6551,15 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 		/* Fill in the logical address of each stripe */
 		tmp = stripe_nr * data_stripes;
 		for (i = 0; i < data_stripes; i++)
-			bbio->raid_map[(i+rot) % num_stripes] =
+			bioc->raid_map[(i + rot) % num_stripes] =
 				em->start + (tmp + i) * map->stripe_len;
 
-		bbio->raid_map[(i+rot) % map->num_stripes] = RAID5_P_STRIPE;
+		bioc->raid_map[(i + rot) % map->num_stripes] = RAID5_P_STRIPE;
 		if (map->type & BTRFS_BLOCK_GROUP_RAID6)
-			bbio->raid_map[(i+rot+1) % num_stripes] =
+			bioc->raid_map[(i + rot + 1) % num_stripes] =
 				RAID6_Q_STRIPE;
 
-		sort_parity_stripes(bbio, num_stripes);
+		sort_parity_stripes(bioc, num_stripes);
 	}
 
 	if (need_full_stripe(op))
@@ -6513,15 +6567,15 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 
 	if (dev_replace_is_ongoing && dev_replace->tgtdev != NULL &&
 	    need_full_stripe(op)) {
-		handle_ops_on_dev_replace(op, &bbio, dev_replace, logical,
+		handle_ops_on_dev_replace(op, &bioc, dev_replace, logical,
 					  &num_stripes, &max_errors);
 	}
 
-	*bbio_ret = bbio;
-	bbio->map_type = map->type;
-	bbio->num_stripes = num_stripes;
-	bbio->max_errors = max_errors;
-	bbio->mirror_num = mirror_num;
+	*bioc_ret = bioc;
+	bioc->map_type = map->type;
+	bioc->num_stripes = num_stripes;
+	bioc->max_errors = max_errors;
+	bioc->mirror_num = mirror_num;
 
 	/*
 	 * this is the case that REQ_READ && dev_replace_is_ongoing &&
@@ -6530,9 +6584,9 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 	 */
 	if (patch_the_first_stripe_for_dev_replace && num_stripes > 0) {
 		WARN_ON(num_stripes > 1);
-		bbio->stripes[0].dev = dev_replace->tgtdev;
-		bbio->stripes[0].physical = physical_to_patch_in_first_stripe;
-		bbio->mirror_num = map->num_stripes + 1;
+		bioc->stripes[0].dev = dev_replace->tgtdev;
+		bioc->stripes[0].physical = physical_to_patch_in_first_stripe;
+		bioc->mirror_num = map->num_stripes + 1;
 	}
 out:
 	if (dev_replace_is_ongoing) {
@@ -6546,43 +6600,43 @@ out:
 
 int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 		      u64 logical, u64 *length,
-		      struct btrfs_bio **bbio_ret, int mirror_num)
+		      struct btrfs_io_context **bioc_ret, int mirror_num)
 {
 	if (op == BTRFS_MAP_DISCARD)
 		return __btrfs_map_block_for_discard(fs_info, logical,
-						     length, bbio_ret);
+						     length, bioc_ret);
 
-	return __btrfs_map_block(fs_info, op, logical, length, bbio_ret,
+	return __btrfs_map_block(fs_info, op, logical, length, bioc_ret,
 				 mirror_num, 0);
 }
 
 /* For Scrub/replace */
 int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 		     u64 logical, u64 *length,
-		     struct btrfs_bio **bbio_ret)
+		     struct btrfs_io_context **bioc_ret)
 {
-	return __btrfs_map_block(fs_info, op, logical, length, bbio_ret, 0, 1);
+	return __btrfs_map_block(fs_info, op, logical, length, bioc_ret, 0, 1);
 }
 
-static inline void btrfs_end_bbio(struct btrfs_bio *bbio, struct bio *bio)
+static inline void btrfs_end_bioc(struct btrfs_io_context *bioc, struct bio *bio)
 {
-	bio->bi_private = bbio->private;
-	bio->bi_end_io = bbio->end_io;
+	bio->bi_private = bioc->private;
+	bio->bi_end_io = bioc->end_io;
 	bio_endio(bio);
 
-	btrfs_put_bbio(bbio);
+	btrfs_put_bioc(bioc);
 }
 
 static void btrfs_end_bio(struct bio *bio)
 {
-	struct btrfs_bio *bbio = bio->bi_private;
+	struct btrfs_io_context *bioc = bio->bi_private;
 	int is_orig_bio = 0;
 
 	if (bio->bi_status) {
-		atomic_inc(&bbio->error);
+		atomic_inc(&bioc->error);
 		if (bio->bi_status == BLK_STS_IOERR ||
 		    bio->bi_status == BLK_STS_TARGET) {
-			struct btrfs_device *dev = btrfs_io_bio(bio)->device;
+			struct btrfs_device *dev = btrfs_bio(bio)->device;
 
 			ASSERT(dev->bdev);
 			if (btrfs_op(bio) == BTRFS_MAP_WRITE)
@@ -6597,22 +6651,22 @@ static void btrfs_end_bio(struct bio *bio)
 		}
 	}
 
-	if (bio == bbio->orig_bio)
+	if (bio == bioc->orig_bio)
 		is_orig_bio = 1;
 
-	btrfs_bio_counter_dec(bbio->fs_info);
+	btrfs_bio_counter_dec(bioc->fs_info);
 
-	if (atomic_dec_and_test(&bbio->stripes_pending)) {
+	if (atomic_dec_and_test(&bioc->stripes_pending)) {
 		if (!is_orig_bio) {
 			bio_put(bio);
-			bio = bbio->orig_bio;
+			bio = bioc->orig_bio;
 		}
 
-		btrfs_io_bio(bio)->mirror_num = bbio->mirror_num;
+		btrfs_bio(bio)->mirror_num = bioc->mirror_num;
 		/* only send an error to the higher layers if it is
 		 * beyond the tolerance of the btrfs bio
 		 */
-		if (atomic_read(&bbio->error) > bbio->max_errors) {
+		if (atomic_read(&bioc->error) > bioc->max_errors) {
 			bio->bi_status = BLK_STS_IOERR;
 		} else {
 			/*
@@ -6622,19 +6676,19 @@ static void btrfs_end_bio(struct bio *bio)
 			bio->bi_status = BLK_STS_OK;
 		}
 
-		btrfs_end_bbio(bbio, bio);
+		btrfs_end_bioc(bioc, bio);
 	} else if (!is_orig_bio) {
 		bio_put(bio);
 	}
 }
 
-static void submit_stripe_bio(struct btrfs_bio *bbio, struct bio *bio,
+static void submit_stripe_bio(struct btrfs_io_context *bioc, struct bio *bio,
 			      u64 physical, struct btrfs_device *dev)
 {
-	struct btrfs_fs_info *fs_info = bbio->fs_info;
+	struct btrfs_fs_info *fs_info = bioc->fs_info;
 
-	bio->bi_private = bbio;
-	btrfs_io_bio(bio)->device = dev;
+	bio->bi_private = bioc;
+	btrfs_bio(bio)->device = dev;
 	bio->bi_end_io = btrfs_end_bio;
 	bio->bi_iter.bi_sector = physical >> 9;
 	/*
@@ -6663,20 +6717,20 @@ static void submit_stripe_bio(struct btrfs_bio *bbio, struct bio *bio,
 	btrfsic_submit_bio(bio);
 }
 
-static void bbio_error(struct btrfs_bio *bbio, struct bio *bio, u64 logical)
+static void bioc_error(struct btrfs_io_context *bioc, struct bio *bio, u64 logical)
 {
-	atomic_inc(&bbio->error);
-	if (atomic_dec_and_test(&bbio->stripes_pending)) {
+	atomic_inc(&bioc->error);
+	if (atomic_dec_and_test(&bioc->stripes_pending)) {
 		/* Should be the original bio. */
-		WARN_ON(bio != bbio->orig_bio);
+		WARN_ON(bio != bioc->orig_bio);
 
-		btrfs_io_bio(bio)->mirror_num = bbio->mirror_num;
+		btrfs_bio(bio)->mirror_num = bioc->mirror_num;
 		bio->bi_iter.bi_sector = logical >> 9;
-		if (atomic_read(&bbio->error) > bbio->max_errors)
+		if (atomic_read(&bioc->error) > bioc->max_errors)
 			bio->bi_status = BLK_STS_IOERR;
 		else
 			bio->bi_status = BLK_STS_OK;
-		btrfs_end_bbio(bbio, bio);
+		btrfs_end_bioc(bioc, bio);
 	}
 }
 
@@ -6691,36 +6745,34 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 	int ret;
 	int dev_nr;
 	int total_devs;
-	struct btrfs_bio *bbio = NULL;
+	struct btrfs_io_context *bioc = NULL;
 
 	length = bio->bi_iter.bi_size;
 	map_length = length;
 
 	btrfs_bio_counter_inc_blocked(fs_info);
 	ret = __btrfs_map_block(fs_info, btrfs_op(bio), logical,
-				&map_length, &bbio, mirror_num, 1);
+				&map_length, &bioc, mirror_num, 1);
 	if (ret) {
 		btrfs_bio_counter_dec(fs_info);
 		return errno_to_blk_status(ret);
 	}
 
-	total_devs = bbio->num_stripes;
-	bbio->orig_bio = first_bio;
-	bbio->private = first_bio->bi_private;
-	bbio->end_io = first_bio->bi_end_io;
-	bbio->fs_info = fs_info;
-	atomic_set(&bbio->stripes_pending, bbio->num_stripes);
+	total_devs = bioc->num_stripes;
+	bioc->orig_bio = first_bio;
+	bioc->private = first_bio->bi_private;
+	bioc->end_io = first_bio->bi_end_io;
+	atomic_set(&bioc->stripes_pending, bioc->num_stripes);
 
-	if ((bbio->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) &&
+	if ((bioc->map_type & BTRFS_BLOCK_GROUP_RAID56_MASK) &&
 	    ((btrfs_op(bio) == BTRFS_MAP_WRITE) || (mirror_num > 1))) {
 		/* In this case, map_length has been set to the length of
 		   a single stripe; not the whole write */
 		if (btrfs_op(bio) == BTRFS_MAP_WRITE) {
-			ret = raid56_parity_write(fs_info, bio, bbio,
-						  map_length);
+			ret = raid56_parity_write(bio, bioc, map_length);
 		} else {
-			ret = raid56_parity_recover(fs_info, bio, bbio,
-						    map_length, mirror_num, 1);
+			ret = raid56_parity_recover(bio, bioc, map_length,
+						    mirror_num, 1);
 		}
 
 		btrfs_bio_counter_dec(fs_info);
@@ -6735,12 +6787,12 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 	}
 
 	for (dev_nr = 0; dev_nr < total_devs; dev_nr++) {
-		dev = bbio->stripes[dev_nr].dev;
+		dev = bioc->stripes[dev_nr].dev;
 		if (!dev || !dev->bdev || test_bit(BTRFS_DEV_STATE_MISSING,
 						   &dev->dev_state) ||
 		    (btrfs_op(first_bio) == BTRFS_MAP_WRITE &&
 		    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))) {
-			bbio_error(bbio, first_bio, logical);
+			bioc_error(bioc, first_bio, logical);
 			continue;
 		}
 
@@ -6749,12 +6801,39 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 		else
 			bio = first_bio;
 
-		submit_stripe_bio(bbio, bio, bbio->stripes[dev_nr].physical, dev);
+		submit_stripe_bio(bioc, bio, bioc->stripes[dev_nr].physical, dev);
 	}
 	btrfs_bio_counter_dec(fs_info);
 	return BLK_STS_OK;
 }
 
+static bool dev_args_match_fs_devices(const struct btrfs_dev_lookup_args *args,
+				      const struct btrfs_fs_devices *fs_devices)
+{
+	if (args->fsid == NULL)
+		return true;
+	if (memcmp(fs_devices->metadata_uuid, args->fsid, BTRFS_FSID_SIZE) == 0)
+		return true;
+	return false;
+}
+
+static bool dev_args_match_device(const struct btrfs_dev_lookup_args *args,
+				  const struct btrfs_device *device)
+{
+	ASSERT((args->devid != (u64)-1) || args->missing);
+
+	if ((args->devid != (u64)-1) && device->devid != args->devid)
+		return false;
+	if (args->uuid && memcmp(device->uuid, args->uuid, BTRFS_UUID_SIZE) != 0)
+		return false;
+	if (!args->missing)
+		return true;
+	if (test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state) &&
+	    !device->bdev)
+		return true;
+	return false;
+}
+
 /*
  * Find a device specified by @devid or @uuid in the list of @fs_devices, or
  * return NULL.
@@ -6762,31 +6841,25 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
  * If devid and uuid are both specified, the match must be exact, otherwise
  * only devid is used.
  */
-struct btrfs_device *btrfs_find_device(struct btrfs_fs_devices *fs_devices,
-				       u64 devid, u8 *uuid, u8 *fsid)
+struct btrfs_device *btrfs_find_device(const struct btrfs_fs_devices *fs_devices,
+				       const struct btrfs_dev_lookup_args *args)
 {
 	struct btrfs_device *device;
 	struct btrfs_fs_devices *seed_devs;
 
-	if (!fsid || !memcmp(fs_devices->metadata_uuid, fsid, BTRFS_FSID_SIZE)) {
+	if (dev_args_match_fs_devices(args, fs_devices)) {
 		list_for_each_entry(device, &fs_devices->devices, dev_list) {
-			if (device->devid == devid &&
-			    (!uuid || memcmp(device->uuid, uuid,
-					     BTRFS_UUID_SIZE) == 0))
+			if (dev_args_match_device(args, device))
 				return device;
 		}
 	}
 
 	list_for_each_entry(seed_devs, &fs_devices->seed_list, seed_list) {
-		if (!fsid ||
-		    !memcmp(seed_devs->metadata_uuid, fsid, BTRFS_FSID_SIZE)) {
-			list_for_each_entry(device, &seed_devs->devices,
-					    dev_list) {
-				if (device->devid == devid &&
-				    (!uuid || memcmp(device->uuid, uuid,
-						     BTRFS_UUID_SIZE) == 0))
-					return device;
-			}
+		if (!dev_args_match_fs_devices(args, seed_devs))
+			continue;
+		list_for_each_entry(device, &seed_devs->devices, dev_list) {
+			if (dev_args_match_device(args, device))
+				return device;
 		}
 	}
 
@@ -6952,6 +7025,7 @@ static void warn_32bit_meta_chunk(struct btrfs_fs_info *fs_info,
 static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 			  struct btrfs_chunk *chunk)
 {
+	BTRFS_DEV_LOOKUP_ARGS(args);
 	struct btrfs_fs_info *fs_info = leaf->fs_info;
 	struct extent_map_tree *map_tree = &fs_info->mapping_tree;
 	struct map_lookup *map;
@@ -7029,11 +7103,12 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 		map->stripes[i].physical =
 			btrfs_stripe_offset_nr(leaf, chunk, i);
 		devid = btrfs_stripe_devid_nr(leaf, chunk, i);
+		args.devid = devid;
 		read_extent_buffer(leaf, uuid, (unsigned long)
 				   btrfs_stripe_dev_uuid_nr(chunk, i),
 				   BTRFS_UUID_SIZE);
-		map->stripes[i].dev = btrfs_find_device(fs_info->fs_devices,
-							devid, uuid, NULL);
+		args.uuid = uuid;
+		map->stripes[i].dev = btrfs_find_device(fs_info->fs_devices, &args);
 		if (!map->stripes[i].dev &&
 		    !btrfs_test_opt(fs_info, DEGRADED)) {
 			free_extent_map(em);
@@ -7151,6 +7226,7 @@ static struct btrfs_fs_devices *open_seed_devices(struct btrfs_fs_info *fs_info,
 static int read_one_dev(struct extent_buffer *leaf,
 			struct btrfs_dev_item *dev_item)
 {
+	BTRFS_DEV_LOOKUP_ARGS(args);
 	struct btrfs_fs_info *fs_info = leaf->fs_info;
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	struct btrfs_device *device;
@@ -7159,11 +7235,13 @@ static int read_one_dev(struct extent_buffer *leaf,
 	u8 fs_uuid[BTRFS_FSID_SIZE];
 	u8 dev_uuid[BTRFS_UUID_SIZE];
 
-	devid = btrfs_device_id(leaf, dev_item);
+	devid = args.devid = btrfs_device_id(leaf, dev_item);
 	read_extent_buffer(leaf, dev_uuid, btrfs_device_uuid(dev_item),
 			   BTRFS_UUID_SIZE);
 	read_extent_buffer(leaf, fs_uuid, btrfs_device_fsid(dev_item),
 			   BTRFS_FSID_SIZE);
+	args.uuid = dev_uuid;
+	args.fsid = fs_uuid;
 
 	if (memcmp(fs_uuid, fs_devices->metadata_uuid, BTRFS_FSID_SIZE)) {
 		fs_devices = open_seed_devices(fs_info, fs_uuid);
@@ -7171,8 +7249,7 @@ static int read_one_dev(struct extent_buffer *leaf,
 			return PTR_ERR(fs_devices);
 	}
 
-	device = btrfs_find_device(fs_info->fs_devices, devid, dev_uuid,
-				   fs_uuid);
+	device = btrfs_find_device(fs_info->fs_devices, &args);
 	if (!device) {
 		if (!btrfs_test_opt(fs_info, DEGRADED)) {
 			btrfs_report_missing_device(fs_info, devid,
@@ -7841,12 +7918,14 @@ static void btrfs_dev_stat_print_on_load(struct btrfs_device *dev)
 int btrfs_get_dev_stats(struct btrfs_fs_info *fs_info,
 			struct btrfs_ioctl_get_dev_stats *stats)
 {
+	BTRFS_DEV_LOOKUP_ARGS(args);
 	struct btrfs_device *dev;
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	int i;
 
 	mutex_lock(&fs_devices->device_list_mutex);
-	dev = btrfs_find_device(fs_info->fs_devices, stats->devid, NULL, NULL);
+	args.devid = stats->devid;
+	dev = btrfs_find_device(fs_info->fs_devices, &args);
 	mutex_unlock(&fs_devices->device_list_mutex);
 
 	if (!dev) {
@@ -7922,6 +8001,7 @@ static int verify_one_dev_extent(struct btrfs_fs_info *fs_info,
 				 u64 chunk_offset, u64 devid,
 				 u64 physical_offset, u64 physical_len)
 {
+	struct btrfs_dev_lookup_args args = { .devid = devid };
 	struct extent_map_tree *em_tree = &fs_info->mapping_tree;
 	struct extent_map *em;
 	struct map_lookup *map;
@@ -7977,7 +8057,7 @@ static int verify_one_dev_extent(struct btrfs_fs_info *fs_info,
 	}
 
 	/* Make sure no dev extent is beyond device boundary */
-	dev = btrfs_find_device(fs_info->fs_devices, devid, NULL, NULL);
+	dev = btrfs_find_device(fs_info->fs_devices, &args);
 	if (!dev) {
 		btrfs_err(fs_info, "failed to find devid %llu", devid);
 		ret = -EUCLEAN;