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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /fs/btrfs/dev-replace.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/btrfs/dev-replace.c')
-rw-r--r--fs/btrfs/dev-replace.c1291
1 files changed, 1291 insertions, 0 deletions
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
new file mode 100644
index 0000000000..fe6ba17a05
--- /dev/null
+++ b/fs/btrfs/dev-replace.c
@@ -0,0 +1,1291 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STRATO AG 2012. All rights reserved.
+ */
+
+#include <linux/sched.h>
+#include <linux/bio.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/kthread.h>
+#include <linux/math64.h>
+#include "misc.h"
+#include "ctree.h"
+#include "extent_map.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "print-tree.h"
+#include "volumes.h"
+#include "async-thread.h"
+#include "check-integrity.h"
+#include "dev-replace.h"
+#include "sysfs.h"
+#include "zoned.h"
+#include "block-group.h"
+#include "fs.h"
+#include "accessors.h"
+#include "scrub.h"
+
+/*
+ * Device replace overview
+ *
+ * [Objective]
+ * To copy all extents (both new and on-disk) from source device to target
+ * device, while still keeping the filesystem read-write.
+ *
+ * [Method]
+ * There are two main methods involved:
+ *
+ * - Write duplication
+ *
+ * All new writes will be written to both target and source devices, so even
+ * if replace gets canceled, sources device still contains up-to-date data.
+ *
+ * Location: handle_ops_on_dev_replace() from btrfs_map_block()
+ * Start: btrfs_dev_replace_start()
+ * End: btrfs_dev_replace_finishing()
+ * Content: Latest data/metadata
+ *
+ * - Copy existing extents
+ *
+ * This happens by re-using scrub facility, as scrub also iterates through
+ * existing extents from commit root.
+ *
+ * Location: scrub_write_block_to_dev_replace() from
+ * scrub_block_complete()
+ * Content: Data/meta from commit root.
+ *
+ * Due to the content difference, we need to avoid nocow write when dev-replace
+ * is happening. This is done by marking the block group read-only and waiting
+ * for NOCOW writes.
+ *
+ * After replace is done, the finishing part is done by swapping the target and
+ * source devices.
+ *
+ * Location: btrfs_dev_replace_update_device_in_mapping_tree() from
+ * btrfs_dev_replace_finishing()
+ */
+
+static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
+ int scrub_ret);
+static int btrfs_dev_replace_kthread(void *data);
+
+int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_dev_lookup_args args = { .devid = BTRFS_DEV_REPLACE_DEVID };
+ struct btrfs_key key;
+ struct btrfs_root *dev_root = fs_info->dev_root;
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+ struct extent_buffer *eb;
+ int slot;
+ int ret = 0;
+ struct btrfs_path *path = NULL;
+ int item_size;
+ struct btrfs_dev_replace_item *ptr;
+ u64 src_devid;
+
+ if (!dev_root)
+ return 0;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ key.objectid = 0;
+ key.type = BTRFS_DEV_REPLACE_KEY;
+ key.offset = 0;
+ ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
+ if (ret) {
+no_valid_dev_replace_entry_found:
+ /*
+ * We don't have a replace item or it's corrupted. If there is
+ * a replace target, fail the mount.
+ */
+ if (btrfs_find_device(fs_info->fs_devices, &args)) {
+ btrfs_err(fs_info,
+ "found replace target device without a valid replace item");
+ ret = -EUCLEAN;
+ goto out;
+ }
+ ret = 0;
+ dev_replace->replace_state =
+ BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
+ dev_replace->cont_reading_from_srcdev_mode =
+ BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS;
+ dev_replace->time_started = 0;
+ dev_replace->time_stopped = 0;
+ atomic64_set(&dev_replace->num_write_errors, 0);
+ atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
+ dev_replace->cursor_left = 0;
+ dev_replace->committed_cursor_left = 0;
+ dev_replace->cursor_left_last_write_of_item = 0;
+ dev_replace->cursor_right = 0;
+ dev_replace->srcdev = NULL;
+ dev_replace->tgtdev = NULL;
+ dev_replace->is_valid = 0;
+ dev_replace->item_needs_writeback = 0;
+ goto out;
+ }
+ slot = path->slots[0];
+ eb = path->nodes[0];
+ item_size = btrfs_item_size(eb, slot);
+ ptr = btrfs_item_ptr(eb, slot, struct btrfs_dev_replace_item);
+
+ if (item_size != sizeof(struct btrfs_dev_replace_item)) {
+ btrfs_warn(fs_info,
+ "dev_replace entry found has unexpected size, ignore entry");
+ goto no_valid_dev_replace_entry_found;
+ }
+
+ src_devid = btrfs_dev_replace_src_devid(eb, ptr);
+ dev_replace->cont_reading_from_srcdev_mode =
+ btrfs_dev_replace_cont_reading_from_srcdev_mode(eb, ptr);
+ dev_replace->replace_state = btrfs_dev_replace_replace_state(eb, ptr);
+ dev_replace->time_started = btrfs_dev_replace_time_started(eb, ptr);
+ dev_replace->time_stopped =
+ btrfs_dev_replace_time_stopped(eb, ptr);
+ atomic64_set(&dev_replace->num_write_errors,
+ btrfs_dev_replace_num_write_errors(eb, ptr));
+ atomic64_set(&dev_replace->num_uncorrectable_read_errors,
+ btrfs_dev_replace_num_uncorrectable_read_errors(eb, ptr));
+ dev_replace->cursor_left = btrfs_dev_replace_cursor_left(eb, ptr);
+ dev_replace->committed_cursor_left = dev_replace->cursor_left;
+ dev_replace->cursor_left_last_write_of_item = dev_replace->cursor_left;
+ dev_replace->cursor_right = btrfs_dev_replace_cursor_right(eb, ptr);
+ dev_replace->is_valid = 1;
+
+ dev_replace->item_needs_writeback = 0;
+ switch (dev_replace->replace_state) {
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
+ /*
+ * We don't have an active replace item but if there is a
+ * replace target, fail the mount.
+ */
+ if (btrfs_find_device(fs_info->fs_devices, &args)) {
+ btrfs_err(fs_info,
+"replace without active item, run 'device scan --forget' on the target device");
+ ret = -EUCLEAN;
+ } else {
+ dev_replace->srcdev = NULL;
+ dev_replace->tgtdev = NULL;
+ }
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+ dev_replace->tgtdev = btrfs_find_device(fs_info->fs_devices, &args);
+ args.devid = src_devid;
+ dev_replace->srcdev = btrfs_find_device(fs_info->fs_devices, &args);
+
+ /*
+ * allow 'btrfs dev replace_cancel' if src/tgt device is
+ * missing
+ */
+ if (!dev_replace->srcdev &&
+ !btrfs_test_opt(fs_info, DEGRADED)) {
+ ret = -EIO;
+ btrfs_warn(fs_info,
+ "cannot mount because device replace operation is ongoing and");
+ btrfs_warn(fs_info,
+ "srcdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
+ src_devid);
+ }
+ if (!dev_replace->tgtdev &&
+ !btrfs_test_opt(fs_info, DEGRADED)) {
+ ret = -EIO;
+ btrfs_warn(fs_info,
+ "cannot mount because device replace operation is ongoing and");
+ btrfs_warn(fs_info,
+ "tgtdev (devid %llu) is missing, need to run 'btrfs dev scan'?",
+ BTRFS_DEV_REPLACE_DEVID);
+ }
+ if (dev_replace->tgtdev) {
+ if (dev_replace->srcdev) {
+ dev_replace->tgtdev->total_bytes =
+ dev_replace->srcdev->total_bytes;
+ dev_replace->tgtdev->disk_total_bytes =
+ dev_replace->srcdev->disk_total_bytes;
+ dev_replace->tgtdev->commit_total_bytes =
+ dev_replace->srcdev->commit_total_bytes;
+ dev_replace->tgtdev->bytes_used =
+ dev_replace->srcdev->bytes_used;
+ dev_replace->tgtdev->commit_bytes_used =
+ dev_replace->srcdev->commit_bytes_used;
+ }
+ set_bit(BTRFS_DEV_STATE_REPLACE_TGT,
+ &dev_replace->tgtdev->dev_state);
+
+ WARN_ON(fs_info->fs_devices->rw_devices == 0);
+ dev_replace->tgtdev->io_width = fs_info->sectorsize;
+ dev_replace->tgtdev->io_align = fs_info->sectorsize;
+ dev_replace->tgtdev->sector_size = fs_info->sectorsize;
+ dev_replace->tgtdev->fs_info = fs_info;
+ set_bit(BTRFS_DEV_STATE_IN_FS_METADATA,
+ &dev_replace->tgtdev->dev_state);
+ }
+ break;
+ }
+
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+/*
+ * Initialize a new device for device replace target from a given source dev
+ * and path.
+ *
+ * Return 0 and new device in @device_out, otherwise return < 0
+ */
+static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
+ const char *device_path,
+ struct btrfs_device *srcdev,
+ struct btrfs_device **device_out)
+{
+ struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+ struct btrfs_device *device;
+ struct block_device *bdev;
+ u64 devid = BTRFS_DEV_REPLACE_DEVID;
+ int ret = 0;
+
+ *device_out = NULL;
+ if (srcdev->fs_devices->seeding) {
+ btrfs_err(fs_info, "the filesystem is a seed filesystem!");
+ return -EINVAL;
+ }
+
+ bdev = blkdev_get_by_path(device_path, BLK_OPEN_WRITE,
+ fs_info->bdev_holder, NULL);
+ if (IS_ERR(bdev)) {
+ btrfs_err(fs_info, "target device %s is invalid!", device_path);
+ return PTR_ERR(bdev);
+ }
+
+ if (!btrfs_check_device_zone_type(fs_info, bdev)) {
+ btrfs_err(fs_info,
+ "dev-replace: zoned type of target device mismatch with filesystem");
+ ret = -EINVAL;
+ goto error;
+ }
+
+ sync_blockdev(bdev);
+
+ list_for_each_entry(device, &fs_devices->devices, dev_list) {
+ if (device->bdev == bdev) {
+ btrfs_err(fs_info,
+ "target device is in the filesystem!");
+ ret = -EEXIST;
+ goto error;
+ }
+ }
+
+
+ if (bdev_nr_bytes(bdev) < btrfs_device_get_total_bytes(srcdev)) {
+ btrfs_err(fs_info,
+ "target device is smaller than source device!");
+ ret = -EINVAL;
+ goto error;
+ }
+
+
+ device = btrfs_alloc_device(NULL, &devid, NULL, device_path);
+ if (IS_ERR(device)) {
+ ret = PTR_ERR(device);
+ goto error;
+ }
+
+ ret = lookup_bdev(device_path, &device->devt);
+ if (ret)
+ goto error;
+
+ set_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
+ device->generation = 0;
+ device->io_width = fs_info->sectorsize;
+ device->io_align = fs_info->sectorsize;
+ device->sector_size = fs_info->sectorsize;
+ device->total_bytes = btrfs_device_get_total_bytes(srcdev);
+ device->disk_total_bytes = btrfs_device_get_disk_total_bytes(srcdev);
+ device->bytes_used = btrfs_device_get_bytes_used(srcdev);
+ device->commit_total_bytes = srcdev->commit_total_bytes;
+ device->commit_bytes_used = device->bytes_used;
+ device->fs_info = fs_info;
+ device->bdev = bdev;
+ set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
+ set_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
+ device->holder = fs_info->bdev_holder;
+ device->dev_stats_valid = 1;
+ set_blocksize(device->bdev, BTRFS_BDEV_BLOCKSIZE);
+ device->fs_devices = fs_devices;
+
+ ret = btrfs_get_dev_zone_info(device, false);
+ if (ret)
+ goto error;
+
+ mutex_lock(&fs_devices->device_list_mutex);
+ list_add(&device->dev_list, &fs_devices->devices);
+ fs_devices->num_devices++;
+ fs_devices->open_devices++;
+ mutex_unlock(&fs_devices->device_list_mutex);
+
+ *device_out = device;
+ return 0;
+
+error:
+ blkdev_put(bdev, fs_info->bdev_holder);
+ return ret;
+}
+
+/*
+ * called from commit_transaction. Writes changed device replace state to
+ * disk.
+ */
+int btrfs_run_dev_replace(struct btrfs_trans_handle *trans)
+{
+ struct btrfs_fs_info *fs_info = trans->fs_info;
+ int ret;
+ struct btrfs_root *dev_root = fs_info->dev_root;
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct extent_buffer *eb;
+ struct btrfs_dev_replace_item *ptr;
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+
+ down_read(&dev_replace->rwsem);
+ if (!dev_replace->is_valid ||
+ !dev_replace->item_needs_writeback) {
+ up_read(&dev_replace->rwsem);
+ return 0;
+ }
+ up_read(&dev_replace->rwsem);
+
+ key.objectid = 0;
+ key.type = BTRFS_DEV_REPLACE_KEY;
+ key.offset = 0;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
+ if (ret < 0) {
+ btrfs_warn(fs_info,
+ "error %d while searching for dev_replace item!",
+ ret);
+ goto out;
+ }
+
+ if (ret == 0 &&
+ btrfs_item_size(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
+ /*
+ * need to delete old one and insert a new one.
+ * Since no attempt is made to recover any old state, if the
+ * dev_replace state is 'running', the data on the target
+ * drive is lost.
+ * It would be possible to recover the state: just make sure
+ * that the beginning of the item is never changed and always
+ * contains all the essential information. Then read this
+ * minimal set of information and use it as a base for the
+ * new state.
+ */
+ ret = btrfs_del_item(trans, dev_root, path);
+ if (ret != 0) {
+ btrfs_warn(fs_info,
+ "delete too small dev_replace item failed %d!",
+ ret);
+ goto out;
+ }
+ ret = 1;
+ }
+
+ if (ret == 1) {
+ /* need to insert a new item */
+ btrfs_release_path(path);
+ ret = btrfs_insert_empty_item(trans, dev_root, path,
+ &key, sizeof(*ptr));
+ if (ret < 0) {
+ btrfs_warn(fs_info,
+ "insert dev_replace item failed %d!", ret);
+ goto out;
+ }
+ }
+
+ eb = path->nodes[0];
+ ptr = btrfs_item_ptr(eb, path->slots[0],
+ struct btrfs_dev_replace_item);
+
+ down_write(&dev_replace->rwsem);
+ if (dev_replace->srcdev)
+ btrfs_set_dev_replace_src_devid(eb, ptr,
+ dev_replace->srcdev->devid);
+ else
+ btrfs_set_dev_replace_src_devid(eb, ptr, (u64)-1);
+ btrfs_set_dev_replace_cont_reading_from_srcdev_mode(eb, ptr,
+ dev_replace->cont_reading_from_srcdev_mode);
+ btrfs_set_dev_replace_replace_state(eb, ptr,
+ dev_replace->replace_state);
+ btrfs_set_dev_replace_time_started(eb, ptr, dev_replace->time_started);
+ btrfs_set_dev_replace_time_stopped(eb, ptr, dev_replace->time_stopped);
+ btrfs_set_dev_replace_num_write_errors(eb, ptr,
+ atomic64_read(&dev_replace->num_write_errors));
+ btrfs_set_dev_replace_num_uncorrectable_read_errors(eb, ptr,
+ atomic64_read(&dev_replace->num_uncorrectable_read_errors));
+ dev_replace->cursor_left_last_write_of_item =
+ dev_replace->cursor_left;
+ btrfs_set_dev_replace_cursor_left(eb, ptr,
+ dev_replace->cursor_left_last_write_of_item);
+ btrfs_set_dev_replace_cursor_right(eb, ptr,
+ dev_replace->cursor_right);
+ dev_replace->item_needs_writeback = 0;
+ up_write(&dev_replace->rwsem);
+
+ btrfs_mark_buffer_dirty(trans, eb);
+
+out:
+ btrfs_free_path(path);
+
+ return ret;
+}
+
+static int mark_block_group_to_copy(struct btrfs_fs_info *fs_info,
+ struct btrfs_device *src_dev)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct btrfs_key found_key;
+ struct btrfs_root *root = fs_info->dev_root;
+ struct btrfs_dev_extent *dev_extent = NULL;
+ struct btrfs_block_group *cache;
+ struct btrfs_trans_handle *trans;
+ int iter_ret = 0;
+ int ret = 0;
+ u64 chunk_offset;
+
+ /* Do not use "to_copy" on non zoned filesystem for now */
+ if (!btrfs_is_zoned(fs_info))
+ return 0;
+
+ mutex_lock(&fs_info->chunk_mutex);
+
+ /* Ensure we don't have pending new block group */
+ spin_lock(&fs_info->trans_lock);
+ while (fs_info->running_transaction &&
+ !list_empty(&fs_info->running_transaction->dev_update_list)) {
+ spin_unlock(&fs_info->trans_lock);
+ mutex_unlock(&fs_info->chunk_mutex);
+ trans = btrfs_attach_transaction(root);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ mutex_lock(&fs_info->chunk_mutex);
+ if (ret == -ENOENT) {
+ spin_lock(&fs_info->trans_lock);
+ continue;
+ } else {
+ goto unlock;
+ }
+ }
+
+ ret = btrfs_commit_transaction(trans);
+ mutex_lock(&fs_info->chunk_mutex);
+ if (ret)
+ goto unlock;
+
+ spin_lock(&fs_info->trans_lock);
+ }
+ spin_unlock(&fs_info->trans_lock);
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+
+ path->reada = READA_FORWARD;
+ path->search_commit_root = 1;
+ path->skip_locking = 1;
+
+ key.objectid = src_dev->devid;
+ key.type = BTRFS_DEV_EXTENT_KEY;
+ key.offset = 0;
+
+ btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
+ struct extent_buffer *leaf = path->nodes[0];
+
+ if (found_key.objectid != src_dev->devid)
+ break;
+
+ if (found_key.type != BTRFS_DEV_EXTENT_KEY)
+ break;
+
+ if (found_key.offset < key.offset)
+ break;
+
+ dev_extent = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_extent);
+
+ chunk_offset = btrfs_dev_extent_chunk_offset(leaf, dev_extent);
+
+ cache = btrfs_lookup_block_group(fs_info, chunk_offset);
+ if (!cache)
+ continue;
+
+ set_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
+ btrfs_put_block_group(cache);
+ }
+ if (iter_ret < 0)
+ ret = iter_ret;
+
+ btrfs_free_path(path);
+unlock:
+ mutex_unlock(&fs_info->chunk_mutex);
+
+ return ret;
+}
+
+bool btrfs_finish_block_group_to_copy(struct btrfs_device *srcdev,
+ struct btrfs_block_group *cache,
+ u64 physical)
+{
+ struct btrfs_fs_info *fs_info = cache->fs_info;
+ struct extent_map *em;
+ struct map_lookup *map;
+ u64 chunk_offset = cache->start;
+ int num_extents, cur_extent;
+ int i;
+
+ /* Do not use "to_copy" on non zoned filesystem for now */
+ if (!btrfs_is_zoned(fs_info))
+ return true;
+
+ spin_lock(&cache->lock);
+ if (test_bit(BLOCK_GROUP_FLAG_REMOVED, &cache->runtime_flags)) {
+ spin_unlock(&cache->lock);
+ return true;
+ }
+ spin_unlock(&cache->lock);
+
+ em = btrfs_get_chunk_map(fs_info, chunk_offset, 1);
+ ASSERT(!IS_ERR(em));
+ map = em->map_lookup;
+
+ num_extents = 0;
+ cur_extent = 0;
+ for (i = 0; i < map->num_stripes; i++) {
+ /* We have more device extent to copy */
+ if (srcdev != map->stripes[i].dev)
+ continue;
+
+ num_extents++;
+ if (physical == map->stripes[i].physical)
+ cur_extent = i;
+ }
+
+ free_extent_map(em);
+
+ if (num_extents > 1 && cur_extent < num_extents - 1) {
+ /*
+ * Has more stripes on this device. Keep this block group
+ * readonly until we finish all the stripes.
+ */
+ return false;
+ }
+
+ /* Last stripe on this device */
+ clear_bit(BLOCK_GROUP_FLAG_TO_COPY, &cache->runtime_flags);
+
+ return true;
+}
+
+static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
+ const char *tgtdev_name, u64 srcdevid, const char *srcdev_name,
+ int read_src)
+{
+ struct btrfs_root *root = fs_info->dev_root;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+ int ret;
+ struct btrfs_device *tgt_device = NULL;
+ struct btrfs_device *src_device = NULL;
+
+ src_device = btrfs_find_device_by_devspec(fs_info, srcdevid,
+ srcdev_name);
+ if (IS_ERR(src_device))
+ return PTR_ERR(src_device);
+
+ if (btrfs_pinned_by_swapfile(fs_info, src_device)) {
+ btrfs_warn_in_rcu(fs_info,
+ "cannot replace device %s (devid %llu) due to active swapfile",
+ btrfs_dev_name(src_device), src_device->devid);
+ return -ETXTBSY;
+ }
+
+ /*
+ * Here we commit the transaction to make sure commit_total_bytes
+ * of all the devices are updated.
+ */
+ trans = btrfs_attach_transaction(root);
+ if (!IS_ERR(trans)) {
+ ret = btrfs_commit_transaction(trans);
+ if (ret)
+ return ret;
+ } else if (PTR_ERR(trans) != -ENOENT) {
+ return PTR_ERR(trans);
+ }
+
+ ret = btrfs_init_dev_replace_tgtdev(fs_info, tgtdev_name,
+ src_device, &tgt_device);
+ if (ret)
+ return ret;
+
+ ret = mark_block_group_to_copy(fs_info, src_device);
+ if (ret)
+ return ret;
+
+ down_write(&dev_replace->rwsem);
+ switch (dev_replace->replace_state) {
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+ ASSERT(0);
+ ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_ALREADY_STARTED;
+ up_write(&dev_replace->rwsem);
+ goto leave;
+ }
+
+ dev_replace->cont_reading_from_srcdev_mode = read_src;
+ dev_replace->srcdev = src_device;
+ dev_replace->tgtdev = tgt_device;
+
+ btrfs_info_in_rcu(fs_info,
+ "dev_replace from %s (devid %llu) to %s started",
+ btrfs_dev_name(src_device),
+ src_device->devid,
+ btrfs_dev_name(tgt_device));
+
+ /*
+ * from now on, the writes to the srcdev are all duplicated to
+ * go to the tgtdev as well (refer to btrfs_map_block()).
+ */
+ dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
+ dev_replace->time_started = ktime_get_real_seconds();
+ dev_replace->cursor_left = 0;
+ dev_replace->committed_cursor_left = 0;
+ dev_replace->cursor_left_last_write_of_item = 0;
+ dev_replace->cursor_right = 0;
+ dev_replace->is_valid = 1;
+ dev_replace->item_needs_writeback = 1;
+ atomic64_set(&dev_replace->num_write_errors, 0);
+ atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
+ up_write(&dev_replace->rwsem);
+
+ ret = btrfs_sysfs_add_device(tgt_device);
+ if (ret)
+ btrfs_err(fs_info, "kobj add dev failed %d", ret);
+
+ btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
+
+ /*
+ * Commit dev_replace state and reserve 1 item for it.
+ * This is crucial to ensure we won't miss copying extents for new block
+ * groups that are allocated after we started the device replace, and
+ * must be done after setting up the device replace state.
+ */
+ trans = btrfs_start_transaction(root, 1);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ down_write(&dev_replace->rwsem);
+ dev_replace->replace_state =
+ BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED;
+ dev_replace->srcdev = NULL;
+ dev_replace->tgtdev = NULL;
+ up_write(&dev_replace->rwsem);
+ goto leave;
+ }
+
+ ret = btrfs_commit_transaction(trans);
+ WARN_ON(ret);
+
+ /* the disk copy procedure reuses the scrub code */
+ ret = btrfs_scrub_dev(fs_info, src_device->devid, 0,
+ btrfs_device_get_total_bytes(src_device),
+ &dev_replace->scrub_progress, 0, 1);
+
+ ret = btrfs_dev_replace_finishing(fs_info, ret);
+ if (ret == -EINPROGRESS)
+ ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
+
+ return ret;
+
+leave:
+ btrfs_destroy_dev_replace_tgtdev(tgt_device);
+ return ret;
+}
+
+int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
+ struct btrfs_ioctl_dev_replace_args *args)
+{
+ int ret;
+
+ switch (args->start.cont_reading_from_srcdev_mode) {
+ case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
+ case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_AVOID:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
+ args->start.tgtdev_name[0] == '\0')
+ return -EINVAL;
+
+ ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
+ args->start.srcdevid,
+ args->start.srcdev_name,
+ args->start.cont_reading_from_srcdev_mode);
+ args->result = ret;
+ /* don't warn if EINPROGRESS, someone else might be running scrub */
+ if (ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS ||
+ ret == BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR)
+ return 0;
+
+ return ret;
+}
+
+/*
+ * blocked until all in-flight bios operations are finished.
+ */
+static void btrfs_rm_dev_replace_blocked(struct btrfs_fs_info *fs_info)
+{
+ set_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
+ wait_event(fs_info->dev_replace.replace_wait, !percpu_counter_sum(
+ &fs_info->dev_replace.bio_counter));
+}
+
+/*
+ * we have removed target device, it is safe to allow new bios request.
+ */
+static void btrfs_rm_dev_replace_unblocked(struct btrfs_fs_info *fs_info)
+{
+ clear_bit(BTRFS_FS_STATE_DEV_REPLACING, &fs_info->fs_state);
+ wake_up(&fs_info->dev_replace.replace_wait);
+}
+
+/*
+ * When finishing the device replace, before swapping the source device with the
+ * target device we must update the chunk allocation state in the target device,
+ * as it is empty because replace works by directly copying the chunks and not
+ * through the normal chunk allocation path.
+ */
+static int btrfs_set_target_alloc_state(struct btrfs_device *srcdev,
+ struct btrfs_device *tgtdev)
+{
+ struct extent_state *cached_state = NULL;
+ u64 start = 0;
+ u64 found_start;
+ u64 found_end;
+ int ret = 0;
+
+ lockdep_assert_held(&srcdev->fs_info->chunk_mutex);
+
+ while (find_first_extent_bit(&srcdev->alloc_state, start,
+ &found_start, &found_end,
+ CHUNK_ALLOCATED, &cached_state)) {
+ ret = set_extent_bit(&tgtdev->alloc_state, found_start,
+ found_end, CHUNK_ALLOCATED, NULL);
+ if (ret)
+ break;
+ start = found_end + 1;
+ }
+
+ free_extent_state(cached_state);
+ return ret;
+}
+
+static void btrfs_dev_replace_update_device_in_mapping_tree(
+ struct btrfs_fs_info *fs_info,
+ struct btrfs_device *srcdev,
+ struct btrfs_device *tgtdev)
+{
+ struct extent_map_tree *em_tree = &fs_info->mapping_tree;
+ struct extent_map *em;
+ struct map_lookup *map;
+ u64 start = 0;
+ int i;
+
+ write_lock(&em_tree->lock);
+ do {
+ em = lookup_extent_mapping(em_tree, start, (u64)-1);
+ if (!em)
+ break;
+ map = em->map_lookup;
+ for (i = 0; i < map->num_stripes; i++)
+ if (srcdev == map->stripes[i].dev)
+ map->stripes[i].dev = tgtdev;
+ start = em->start + em->len;
+ free_extent_map(em);
+ } while (start);
+ write_unlock(&em_tree->lock);
+}
+
+static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
+ int scrub_ret)
+{
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+ struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+ struct btrfs_device *tgt_device;
+ struct btrfs_device *src_device;
+ struct btrfs_root *root = fs_info->tree_root;
+ u8 uuid_tmp[BTRFS_UUID_SIZE];
+ struct btrfs_trans_handle *trans;
+ int ret = 0;
+
+ /* don't allow cancel or unmount to disturb the finishing procedure */
+ mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
+
+ down_read(&dev_replace->rwsem);
+ /* was the operation canceled, or is it finished? */
+ if (dev_replace->replace_state !=
+ BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
+ up_read(&dev_replace->rwsem);
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+ return 0;
+ }
+
+ tgt_device = dev_replace->tgtdev;
+ src_device = dev_replace->srcdev;
+ up_read(&dev_replace->rwsem);
+
+ /*
+ * flush all outstanding I/O and inode extent mappings before the
+ * copy operation is declared as being finished
+ */
+ ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
+ if (ret) {
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+ return ret;
+ }
+ btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
+
+ /*
+ * We have to use this loop approach because at this point src_device
+ * has to be available for transaction commit to complete, yet new
+ * chunks shouldn't be allocated on the device.
+ */
+ while (1) {
+ trans = btrfs_start_transaction(root, 0);
+ if (IS_ERR(trans)) {
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+ return PTR_ERR(trans);
+ }
+ ret = btrfs_commit_transaction(trans);
+ WARN_ON(ret);
+
+ /* Prevent write_all_supers() during the finishing procedure */
+ mutex_lock(&fs_devices->device_list_mutex);
+ /* Prevent new chunks being allocated on the source device */
+ mutex_lock(&fs_info->chunk_mutex);
+
+ if (!list_empty(&src_device->post_commit_list)) {
+ mutex_unlock(&fs_devices->device_list_mutex);
+ mutex_unlock(&fs_info->chunk_mutex);
+ } else {
+ break;
+ }
+ }
+
+ down_write(&dev_replace->rwsem);
+ dev_replace->replace_state =
+ scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
+ : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;
+ dev_replace->tgtdev = NULL;
+ dev_replace->srcdev = NULL;
+ dev_replace->time_stopped = ktime_get_real_seconds();
+ dev_replace->item_needs_writeback = 1;
+
+ /*
+ * Update allocation state in the new device and replace the old device
+ * with the new one in the mapping tree.
+ */
+ if (!scrub_ret) {
+ scrub_ret = btrfs_set_target_alloc_state(src_device, tgt_device);
+ if (scrub_ret)
+ goto error;
+ btrfs_dev_replace_update_device_in_mapping_tree(fs_info,
+ src_device,
+ tgt_device);
+ } else {
+ if (scrub_ret != -ECANCELED)
+ btrfs_err_in_rcu(fs_info,
+ "btrfs_scrub_dev(%s, %llu, %s) failed %d",
+ btrfs_dev_name(src_device),
+ src_device->devid,
+ btrfs_dev_name(tgt_device), scrub_ret);
+error:
+ up_write(&dev_replace->rwsem);
+ mutex_unlock(&fs_info->chunk_mutex);
+ mutex_unlock(&fs_devices->device_list_mutex);
+ btrfs_rm_dev_replace_blocked(fs_info);
+ if (tgt_device)
+ btrfs_destroy_dev_replace_tgtdev(tgt_device);
+ btrfs_rm_dev_replace_unblocked(fs_info);
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+
+ return scrub_ret;
+ }
+
+ btrfs_info_in_rcu(fs_info,
+ "dev_replace from %s (devid %llu) to %s finished",
+ btrfs_dev_name(src_device),
+ src_device->devid,
+ btrfs_dev_name(tgt_device));
+ clear_bit(BTRFS_DEV_STATE_REPLACE_TGT, &tgt_device->dev_state);
+ tgt_device->devid = src_device->devid;
+ src_device->devid = BTRFS_DEV_REPLACE_DEVID;
+ memcpy(uuid_tmp, tgt_device->uuid, sizeof(uuid_tmp));
+ memcpy(tgt_device->uuid, src_device->uuid, sizeof(tgt_device->uuid));
+ memcpy(src_device->uuid, uuid_tmp, sizeof(src_device->uuid));
+ btrfs_device_set_total_bytes(tgt_device, src_device->total_bytes);
+ btrfs_device_set_disk_total_bytes(tgt_device,
+ src_device->disk_total_bytes);
+ btrfs_device_set_bytes_used(tgt_device, src_device->bytes_used);
+ tgt_device->commit_bytes_used = src_device->bytes_used;
+
+ btrfs_assign_next_active_device(src_device, tgt_device);
+
+ list_add(&tgt_device->dev_alloc_list, &fs_devices->alloc_list);
+ fs_devices->rw_devices++;
+
+ up_write(&dev_replace->rwsem);
+ btrfs_rm_dev_replace_blocked(fs_info);
+
+ btrfs_rm_dev_replace_remove_srcdev(src_device);
+
+ btrfs_rm_dev_replace_unblocked(fs_info);
+
+ /*
+ * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
+ * update on-disk dev stats value during commit transaction
+ */
+ atomic_inc(&tgt_device->dev_stats_ccnt);
+
+ /*
+ * this is again a consistent state where no dev_replace procedure
+ * is running, the target device is part of the filesystem, the
+ * source device is not part of the filesystem anymore and its 1st
+ * superblock is scratched out so that it is no longer marked to
+ * belong to this filesystem.
+ */
+ mutex_unlock(&fs_info->chunk_mutex);
+ mutex_unlock(&fs_devices->device_list_mutex);
+
+ /* replace the sysfs entry */
+ btrfs_sysfs_remove_device(src_device);
+ btrfs_sysfs_update_devid(tgt_device);
+ if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &src_device->dev_state))
+ btrfs_scratch_superblocks(fs_info, src_device->bdev,
+ src_device->name->str);
+
+ /* write back the superblocks */
+ trans = btrfs_start_transaction(root, 0);
+ if (!IS_ERR(trans))
+ btrfs_commit_transaction(trans);
+
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+
+ btrfs_rm_dev_replace_free_srcdev(src_device);
+
+ return 0;
+}
+
+/*
+ * Read progress of device replace status according to the state and last
+ * stored position. The value format is the same as for
+ * btrfs_dev_replace::progress_1000
+ */
+static u64 btrfs_dev_replace_progress(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+ u64 ret = 0;
+
+ switch (dev_replace->replace_state) {
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
+ ret = 0;
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
+ ret = 1000;
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+ ret = div64_u64(dev_replace->cursor_left,
+ div_u64(btrfs_device_get_total_bytes(
+ dev_replace->srcdev), 1000));
+ break;
+ }
+
+ return ret;
+}
+
+void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
+ struct btrfs_ioctl_dev_replace_args *args)
+{
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+
+ down_read(&dev_replace->rwsem);
+ /* even if !dev_replace_is_valid, the values are good enough for
+ * the replace_status ioctl */
+ args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
+ args->status.replace_state = dev_replace->replace_state;
+ args->status.time_started = dev_replace->time_started;
+ args->status.time_stopped = dev_replace->time_stopped;
+ args->status.num_write_errors =
+ atomic64_read(&dev_replace->num_write_errors);
+ args->status.num_uncorrectable_read_errors =
+ atomic64_read(&dev_replace->num_uncorrectable_read_errors);
+ args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
+ up_read(&dev_replace->rwsem);
+}
+
+int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+ struct btrfs_device *tgt_device = NULL;
+ struct btrfs_device *src_device = NULL;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *root = fs_info->tree_root;
+ int result;
+ int ret;
+
+ if (sb_rdonly(fs_info->sb))
+ return -EROFS;
+
+ mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
+ down_write(&dev_replace->rwsem);
+ switch (dev_replace->replace_state) {
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
+ result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
+ up_write(&dev_replace->rwsem);
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
+ tgt_device = dev_replace->tgtdev;
+ src_device = dev_replace->srcdev;
+ up_write(&dev_replace->rwsem);
+ ret = btrfs_scrub_cancel(fs_info);
+ if (ret < 0) {
+ result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
+ } else {
+ result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
+ /*
+ * btrfs_dev_replace_finishing() will handle the
+ * cleanup part
+ */
+ btrfs_info_in_rcu(fs_info,
+ "dev_replace from %s (devid %llu) to %s canceled",
+ btrfs_dev_name(src_device), src_device->devid,
+ btrfs_dev_name(tgt_device));
+ }
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+ /*
+ * Scrub doing the replace isn't running so we need to do the
+ * cleanup step of btrfs_dev_replace_finishing() here
+ */
+ result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
+ tgt_device = dev_replace->tgtdev;
+ src_device = dev_replace->srcdev;
+ dev_replace->tgtdev = NULL;
+ dev_replace->srcdev = NULL;
+ dev_replace->replace_state =
+ BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
+ dev_replace->time_stopped = ktime_get_real_seconds();
+ dev_replace->item_needs_writeback = 1;
+
+ up_write(&dev_replace->rwsem);
+
+ /* Scrub for replace must not be running in suspended state */
+ btrfs_scrub_cancel(fs_info);
+
+ trans = btrfs_start_transaction(root, 0);
+ if (IS_ERR(trans)) {
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+ return PTR_ERR(trans);
+ }
+ ret = btrfs_commit_transaction(trans);
+ WARN_ON(ret);
+
+ btrfs_info_in_rcu(fs_info,
+ "suspended dev_replace from %s (devid %llu) to %s canceled",
+ btrfs_dev_name(src_device), src_device->devid,
+ btrfs_dev_name(tgt_device));
+
+ if (tgt_device)
+ btrfs_destroy_dev_replace_tgtdev(tgt_device);
+ break;
+ default:
+ up_write(&dev_replace->rwsem);
+ result = -EINVAL;
+ }
+
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+ return result;
+}
+
+void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+
+ mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
+ down_write(&dev_replace->rwsem);
+
+ switch (dev_replace->replace_state) {
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
+ dev_replace->replace_state =
+ BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
+ dev_replace->time_stopped = ktime_get_real_seconds();
+ dev_replace->item_needs_writeback = 1;
+ btrfs_info(fs_info, "suspending dev_replace for unmount");
+ break;
+ }
+
+ up_write(&dev_replace->rwsem);
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+}
+
+/* resume dev_replace procedure that was interrupted by unmount */
+int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
+{
+ struct task_struct *task;
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+
+ down_write(&dev_replace->rwsem);
+
+ switch (dev_replace->replace_state) {
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
+ up_write(&dev_replace->rwsem);
+ return 0;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
+ break;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+ dev_replace->replace_state =
+ BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED;
+ break;
+ }
+ if (!dev_replace->tgtdev || !dev_replace->tgtdev->bdev) {
+ btrfs_info(fs_info,
+ "cannot continue dev_replace, tgtdev is missing");
+ btrfs_info(fs_info,
+ "you may cancel the operation after 'mount -o degraded'");
+ dev_replace->replace_state =
+ BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
+ up_write(&dev_replace->rwsem);
+ return 0;
+ }
+ up_write(&dev_replace->rwsem);
+
+ /*
+ * This could collide with a paused balance, but the exclusive op logic
+ * should never allow both to start and pause. We don't want to allow
+ * dev-replace to start anyway.
+ */
+ if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
+ down_write(&dev_replace->rwsem);
+ dev_replace->replace_state =
+ BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
+ up_write(&dev_replace->rwsem);
+ btrfs_info(fs_info,
+ "cannot resume dev-replace, other exclusive operation running");
+ return 0;
+ }
+
+ task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
+ return PTR_ERR_OR_ZERO(task);
+}
+
+static int btrfs_dev_replace_kthread(void *data)
+{
+ struct btrfs_fs_info *fs_info = data;
+ struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
+ u64 progress;
+ int ret;
+
+ progress = btrfs_dev_replace_progress(fs_info);
+ progress = div_u64(progress, 10);
+ btrfs_info_in_rcu(fs_info,
+ "continuing dev_replace from %s (devid %llu) to target %s @%u%%",
+ btrfs_dev_name(dev_replace->srcdev),
+ dev_replace->srcdev->devid,
+ btrfs_dev_name(dev_replace->tgtdev),
+ (unsigned int)progress);
+
+ ret = btrfs_scrub_dev(fs_info, dev_replace->srcdev->devid,
+ dev_replace->committed_cursor_left,
+ btrfs_device_get_total_bytes(dev_replace->srcdev),
+ &dev_replace->scrub_progress, 0, 1);
+ ret = btrfs_dev_replace_finishing(fs_info, ret);
+ WARN_ON(ret && ret != -ECANCELED);
+
+ btrfs_exclop_finish(fs_info);
+ return 0;
+}
+
+int __pure btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
+{
+ if (!dev_replace->is_valid)
+ return 0;
+
+ switch (dev_replace->replace_state) {
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
+ return 0;
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
+ case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
+ /*
+ * return true even if tgtdev is missing (this is
+ * something that can happen if the dev_replace
+ * procedure is suspended by an umount and then
+ * the tgtdev is missing (or "btrfs dev scan") was
+ * not called and the filesystem is remounted
+ * in degraded state. This does not stop the
+ * dev_replace procedure. It needs to be canceled
+ * manually if the cancellation is wanted.
+ */
+ break;
+ }
+ return 1;
+}
+
+void btrfs_bio_counter_sub(struct btrfs_fs_info *fs_info, s64 amount)
+{
+ percpu_counter_sub(&fs_info->dev_replace.bio_counter, amount);
+ cond_wake_up_nomb(&fs_info->dev_replace.replace_wait);
+}
+
+void btrfs_bio_counter_inc_blocked(struct btrfs_fs_info *fs_info)
+{
+ while (1) {
+ percpu_counter_inc(&fs_info->dev_replace.bio_counter);
+ if (likely(!test_bit(BTRFS_FS_STATE_DEV_REPLACING,
+ &fs_info->fs_state)))
+ break;
+
+ btrfs_bio_counter_dec(fs_info);
+ wait_event(fs_info->dev_replace.replace_wait,
+ !test_bit(BTRFS_FS_STATE_DEV_REPLACING,
+ &fs_info->fs_state));
+ }
+}