7 files changed, 54 insertions, 18 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e9dc78014f09..746cb6aa1f62 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3649,7 +3649,7 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
 /* scrub.c */
 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
                     u64 end, struct btrfs_scrub_progress *progress,
-                    int readonly);
+                    int readonly, int is_dev_replace);
 void btrfs_scrub_pause(struct btrfs_root *root);
 void btrfs_scrub_pause_super(struct btrfs_root *root);
 void btrfs_scrub_continue(struct btrfs_root *root);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b4d438f6c2b3..98af8379895a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7468,7 +7468,8 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
                  * check to make sure we can actually find a chunk with enough
                  * space to fit our block group in.
                  */
-                if (device->total_bytes > device->bytes_used + min_free) {
+                if (device->total_bytes > device->bytes_used + min_free &&
+                    !device->is_tgtdev_for_dev_replace) {
                         ret = find_free_dev_extent(device, min_free,
                                                    &dev_offset, NULL);
                         if (!ret)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 26f46dad3b0e..e54b5e50c927 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1375,6 +1375,11 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
                 }
         }
 
+        if (device->is_tgtdev_for_dev_replace) {
+                ret = -EINVAL;
+                goto out_free;
+        }
+
         old_size = device->total_bytes;
 
         if (mod < 0) {
@@ -3102,7 +3107,8 @@ static long btrfs_ioctl_scrub(struct btrfs_root *root, void __user *arg)
                 return PTR_ERR(sa);
 
         ret = btrfs_scrub_dev(root->fs_info, sa->devid, sa->start, sa->end,
-                              &sa->progress, sa->flags & BTRFS_SCRUB_READONLY);
+                              &sa->progress, sa->flags & BTRFS_SCRUB_READONLY,
+                              0);
 
         if (copy_to_user(arg, sa, sizeof(*sa)))
                 ret = -EFAULT;
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 6cf23f4f7bb7..460e30bb1884 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -116,6 +116,9 @@ struct scrub_ctx {
         u32                     sectorsize;
         u32                     nodesize;
         u32                     leafsize;
+
+        int                     is_dev_replace;
+
         /*
          * statistics
          */
@@ -284,7 +287,7 @@ static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 }
 
 static noinline_for_stack
-struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev)
+struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 {
         struct scrub_ctx *sctx;
         int             i;
@@ -296,6 +299,7 @@ struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev)
         sctx = kzalloc(sizeof(*sctx), GFP_NOFS);
         if (!sctx)
                 goto nomem;
+        sctx->is_dev_replace = is_dev_replace;
         sctx->pages_per_bio = pages_per_bio;
         sctx->curr = -1;
         sctx->dev_root = dev->dev_root;
@@ -2293,7 +2297,7 @@ static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
 
 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
                     u64 end, struct btrfs_scrub_progress *progress,
-                    int readonly)
+                    int readonly, int is_dev_replace)
 {
         struct scrub_ctx *sctx;
         int ret;
@@ -2356,14 +2360,14 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 
         mutex_lock(&fs_info->fs_devices->device_list_mutex);
         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
-        if (!dev || dev->missing) {
+        if (!dev || (dev->missing && !is_dev_replace)) {
                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
                 scrub_workers_put(fs_info);
                 return -ENODEV;
         }
         mutex_lock(&fs_info->scrub_lock);
 
-        if (!dev->in_fs_metadata) {
+        if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
                 mutex_unlock(&fs_info->scrub_lock);
                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
                 scrub_workers_put(fs_info);
@@ -2376,7 +2380,7 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
                 scrub_workers_put(fs_info);
                 return -EINPROGRESS;
         }
-        sctx = scrub_setup_ctx(dev);
+        sctx = scrub_setup_ctx(dev, is_dev_replace);
         if (IS_ERR(sctx)) {
                 mutex_unlock(&fs_info->scrub_lock);
                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index ef2415896b06..837ad2d27853 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1354,7 +1354,8 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
                 min_stripe_size = BTRFS_STRIPE_LEN;
 
         list_for_each_entry(device, &fs_devices->devices, dev_list) {
-                if (!device->in_fs_metadata || !device->bdev)
+                if (!device->in_fs_metadata || !device->bdev ||
+                    device->is_tgtdev_for_dev_replace)
                         continue;
 
                 avail_space = device->total_bytes - device->bytes_used;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 33ca36b37a6a..31f7af878d96 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -518,8 +518,9 @@ again:
         /* This is the initialized path, it is safe to release the devices. */
         list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
                 if (device->in_fs_metadata) {
-                        if (!latest_transid ||
-                            device->generation > latest_transid) {
+                        if (!device->is_tgtdev_for_dev_replace &&
+                            (!latest_transid ||
+                             device->generation > latest_transid)) {
                                 latest_devid = device->devid;
                                 latest_transid = device->generation;
                                 latest_bdev = device->bdev;
@@ -814,7 +815,7 @@ int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
 
         *length = 0;
 
-        if (start >= device->total_bytes)
+        if (start >= device->total_bytes || device->is_tgtdev_for_dev_replace)
                 return 0;
 
         path = btrfs_alloc_path();
@@ -931,7 +932,7 @@ int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes,
         max_hole_size = 0;
         hole_size = 0;
 
-        if (search_start >= search_end) {
+        if (search_start >= search_end || device->is_tgtdev_for_dev_replace) {
                 ret = -ENOSPC;
                 goto error;
         }
@@ -1114,6 +1115,7 @@ int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
         struct btrfs_key key;
 
         WARN_ON(!device->in_fs_metadata);
+        WARN_ON(device->is_tgtdev_for_dev_replace);
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
@@ -1375,7 +1377,9 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                  * is held.
                  */
                 list_for_each_entry(tmp, devices, dev_list) {
-                        if (tmp->in_fs_metadata && !tmp->bdev) {
+                        if (tmp->in_fs_metadata &&
+                            !tmp->is_tgtdev_for_dev_replace &&
+                            !tmp->bdev) {
                                 device = tmp;
                                 break;
                         }
@@ -1406,6 +1410,12 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                 }
         }
 
+        if (device->is_tgtdev_for_dev_replace) {
+                pr_err("btrfs: unable to remove the dev_replace target dev\n");
+                ret = -EINVAL;
+                goto error_brelse;
+        }
+
         if (device->writeable && root->fs_info->fs_devices->rw_devices == 1) {
                 printk(KERN_ERR "btrfs: unable to remove the only writeable "
                        "device\n");
@@ -1425,6 +1435,11 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
         if (ret)
                 goto error_undo;
 
+        /*
+         * TODO: the superblock still includes this device in its num_devices
+         * counter although write_all_supers() is not locked out. This
+         * could give a filesystem state which requires a degraded mount.
+         */
         ret = btrfs_rm_dev_item(root->fs_info->chunk_root, device);
         if (ret)
                 goto error_undo;
@@ -1808,6 +1823,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         device->dev_root = root->fs_info->dev_root;
         device->bdev = bdev;
         device->in_fs_metadata = 1;
+        device->is_tgtdev_for_dev_replace = 0;
         device->mode = FMODE_EXCL;
         set_blocksize(device->bdev, 4096);
 
@@ -1971,7 +1987,8 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
 
         if (!device->writeable)
                 return -EACCES;
-        if (new_size <= device->total_bytes)
+        if (new_size <= device->total_bytes ||
+            device->is_tgtdev_for_dev_replace)
                 return -EINVAL;
 
         btrfs_set_super_total_bytes(super_copy, old_total + diff);
@@ -2600,7 +2617,8 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
                 size_to_free = div_factor(old_size, 1);
                 size_to_free = min(size_to_free, (u64)1 * 1024 * 1024);
                 if (!device->writeable ||
-                    device->total_bytes - device->bytes_used > size_to_free)
+                    device->total_bytes - device->bytes_used > size_to_free ||
+                    device->is_tgtdev_for_dev_replace)
                         continue;
 
                 ret = btrfs_shrink_device(device, old_size - size_to_free);
@@ -3132,6 +3150,9 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
         u64 old_size = device->total_bytes;
         u64 diff = device->total_bytes - new_size;
 
+        if (device->is_tgtdev_for_dev_replace)
+                return -EINVAL;
+
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
@@ -3401,7 +3422,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                         continue;
                 }
 
-                if (!device->in_fs_metadata)
+                if (!device->in_fs_metadata ||
+                    device->is_tgtdev_for_dev_replace)
                         continue;
 
                 if (device->total_bytes > device->bytes_used)
@@ -4612,6 +4634,7 @@ static void fill_device_from_item(struct extent_buffer *leaf,
         device->io_align = btrfs_device_io_align(leaf, dev_item);
         device->io_width = btrfs_device_io_width(leaf, dev_item);
         device->sector_size = btrfs_device_sector_size(leaf, dev_item);
+        device->is_tgtdev_for_dev_replace = 0;
 
         ptr = (unsigned long)btrfs_device_uuid(dev_item);
         read_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
@@ -4722,7 +4745,7 @@ static int read_one_dev(struct btrfs_root *root,
         fill_device_from_item(leaf, dev_item, device);
         device->dev_root = root->fs_info->dev_root;
         device->in_fs_metadata = 1;
-        if (device->writeable) {
+        if (device->writeable && !device->is_tgtdev_for_dev_replace) {
                 device->fs_devices->total_rw_bytes += device->total_bytes;
                 spin_lock(&root->fs_info->free_chunk_lock);
                 root->fs_info->free_chunk_space += device->total_bytes -
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 802e2ba02f09..8fd5a4d8acc8 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -50,6 +50,7 @@ struct btrfs_device {
         int in_fs_metadata;
         int missing;
         int can_discard;
+        int is_tgtdev_for_dev_replace;
 
         spinlock_t io_lock;