Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: prevent RAID level downgrades when space is low
  Btrfs: account for missing devices in RAID allocation profiles
  Btrfs: EIO when we fail to read tree roots
  Btrfs: fix compiler warnings
  Btrfs: Make async snapshot ioctl more generic
  Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
  Btrfs: Fix a crash when mounting a subvolume
  Btrfs: fix sync subvol/snapshot creation
  Btrfs: Fix page leak in compressed writeback path
  Btrfs: do not BUG if we fail to remove the orphan item for dead snapshots
  Btrfs: fixup return code for btrfs_del_orphan_item
  Btrfs: do not do fast caching if we are allocating blocks for tree_root
  Btrfs: deal with space cache errors better
  Btrfs: fix use after free in O_DIRECT

11 files changed, 207 insertions, 94 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c547cca26a26..51d2e4de34eb 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -696,6 +696,7 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio,
                                    __btree_submit_bio_done);
 }
 
+#ifdef CONFIG_MIGRATION
 static int btree_migratepage(struct address_space *mapping,
                         struct page *newpage, struct page *page)
 {
@@ -712,12 +713,9 @@ static int btree_migratepage(struct address_space *mapping,
         if (page_has_private(page) &&
             !try_to_release_page(page, GFP_KERNEL))
                 return -EAGAIN;
-#ifdef CONFIG_MIGRATION
         return migrate_page(mapping, newpage, page);
-#else
-        return -ENOSYS;
-#endif
 }
+#endif
 
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
@@ -1009,7 +1007,10 @@ static int find_and_setup_root(struct btrfs_root *tree_root,
         blocksize = btrfs_level_size(root, btrfs_root_level(&root->root_item));
         root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
                                      blocksize, generation);
-        BUG_ON(!root->node);
+        if (!root->node || !btrfs_buffer_uptodate(root->node, generation)) {
+                free_extent_buffer(root->node);
+                return -EIO;
+        }
         root->commit_root = btrfs_root_node(root);
         return 0;
 }
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index bcd59c7dfb57..227e5815d838 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -429,6 +429,7 @@ err:
 
 static int cache_block_group(struct btrfs_block_group_cache *cache,
                              struct btrfs_trans_handle *trans,
+                             struct btrfs_root *root,
                              int load_cache_only)
 {
         struct btrfs_fs_info *fs_info = cache->fs_info;
@@ -442,9 +443,12 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
 
         /*
          * We can't do the read from on-disk cache during a commit since we need
-         * to have the normal tree locking.
+         * to have the normal tree locking.  Also if we are currently trying to
+         * allocate blocks for the tree root we can't do the fast caching since
+         * we likely hold important locks.
          */
-        if (!trans->transaction->in_commit) {
+        if (!trans->transaction->in_commit &&
+            (root && root != root->fs_info->tree_root)) {
                 spin_lock(&cache->lock);
                 if (cache->cached != BTRFS_CACHE_NO) {
                         spin_unlock(&cache->lock);
@@ -2741,6 +2745,7 @@ static int cache_save_setup(struct btrfs_block_group_cache *block_group,
         struct btrfs_root *root = block_group->fs_info->tree_root;
         struct inode *inode = NULL;
         u64 alloc_hint = 0;
+        int dcs = BTRFS_DC_ERROR;
         int num_pages = 0;
         int retries = 0;
         int ret = 0;
@@ -2795,6 +2800,8 @@ again:
 
         spin_lock(&block_group->lock);
         if (block_group->cached != BTRFS_CACHE_FINISHED) {
+                /* We're not cached, don't bother trying to write stuff out */
+                dcs = BTRFS_DC_WRITTEN;
                 spin_unlock(&block_group->lock);
                 goto out_put;
         }
@@ -2821,6 +2828,8 @@ again:
         ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages,
                                               num_pages, num_pages,
                                               &alloc_hint);
+        if (!ret)
+                dcs = BTRFS_DC_SETUP;
         btrfs_free_reserved_data_space(inode, num_pages);
 out_put:
         iput(inode);
@@ -2828,10 +2837,7 @@ out_free:
         btrfs_release_path(root, path);
 out:
         spin_lock(&block_group->lock);
-        if (ret)
-                block_group->disk_cache_state = BTRFS_DC_ERROR;
-        else
-                block_group->disk_cache_state = BTRFS_DC_SETUP;
+        block_group->disk_cache_state = dcs;
         spin_unlock(&block_group->lock);
 
         return ret;
@@ -3037,7 +3043,13 @@ static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
 
 u64 btrfs_reduce_alloc_profile(struct btrfs_root *root, u64 flags)
 {
-        u64 num_devices = root->fs_info->fs_devices->rw_devices;
+        /*
+         * we add in the count of missing devices because we want
+         * to make sure that any RAID levels on a degraded FS
+         * continue to be honored.
+         */
+        u64 num_devices = root->fs_info->fs_devices->rw_devices +
+                root->fs_info->fs_devices->missing_devices;
 
         if (num_devices == 1)
                 flags &= ~(BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID0);
@@ -4080,7 +4092,7 @@ static int update_block_group(struct btrfs_trans_handle *trans,
                  * space back to the block group, otherwise we will leak space.
                  */
                 if (!alloc && cache->cached == BTRFS_CACHE_NO)
-                        cache_block_group(cache, trans, 1);
+                        cache_block_group(cache, trans, NULL, 1);
 
                 byte_in_group = bytenr - cache->key.objectid;
                 WARN_ON(byte_in_group > cache->key.offset);
@@ -4930,11 +4942,31 @@ search:
                 btrfs_get_block_group(block_group);
                 search_start = block_group->key.objectid;
 
+                /*
+                 * this can happen if we end up cycling through all the
+                 * raid types, but we want to make sure we only allocate
+                 * for the proper type.
+                 */
+                if (!block_group_bits(block_group, data)) {
+                    u64 extra = BTRFS_BLOCK_GROUP_DUP |
+                                BTRFS_BLOCK_GROUP_RAID1 |
+                                BTRFS_BLOCK_GROUP_RAID10;
+
+                        /*
+                         * if they asked for extra copies and this block group
+                         * doesn't provide them, bail.  This does allow us to
+                         * fill raid0 from raid1.
+                         */
+                        if ((data & extra) && !(block_group->flags & extra))
+                                goto loop;
+                }
+
 have_block_group:
                 if (unlikely(block_group->cached == BTRFS_CACHE_NO)) {
                         u64 free_percent;
 
-                        ret = cache_block_group(block_group, trans, 1);
+                        ret = cache_block_group(block_group, trans,
+                                                orig_root, 1);
                         if (block_group->cached == BTRFS_CACHE_FINISHED)
                                 goto have_block_group;
 
@@ -4958,7 +4990,8 @@ have_block_group:
                         if (loop > LOOP_CACHING_NOWAIT ||
                             (loop > LOOP_FIND_IDEAL &&
                              atomic_read(&space_info->caching_threads) < 2)) {
-                                ret = cache_block_group(block_group, trans, 0);
+                                ret = cache_block_group(block_group, trans,
+                                                        orig_root, 0);
                                 BUG_ON(ret);
                         }
                         found_uncached_bg = true;
@@ -5515,7 +5548,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
         u64 num_bytes = ins->offset;
 
         block_group = btrfs_lookup_block_group(root->fs_info, ins->objectid);
-        cache_block_group(block_group, trans, 0);
+        cache_block_group(block_group, trans, NULL, 0);
         caching_ctl = get_caching_control(block_group);
 
         if (!caching_ctl) {
@@ -6300,9 +6333,13 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
                                            NULL, NULL);
                 BUG_ON(ret < 0);
                 if (ret > 0) {
-                        ret = btrfs_del_orphan_item(trans, tree_root,
-                                                    root->root_key.objectid);
-                        BUG_ON(ret);
+                        /* if we fail to delete the orphan item this time
+                         * around, it'll get picked up the next time.
+                         *
+                         * The most common failure here is just -ENOENT.
+                         */
+                        btrfs_del_orphan_item(trans, tree_root,
+                                              root->root_key.objectid);
                 }
         }
 
@@ -7878,7 +7915,14 @@ static u64 update_block_group_flags(struct btrfs_root *root, u64 flags)
         u64 stripped = BTRFS_BLOCK_GROUP_RAID0 |
                 BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10;
 
-        num_devices = root->fs_info->fs_devices->rw_devices;
+        /*
+         * we add in the count of missing devices because we want
+         * to make sure that any RAID levels on a degraded FS
+         * continue to be honored.
+         */
+        num_devices = root->fs_info->fs_devices->rw_devices +
+                root->fs_info->fs_devices->missing_devices;
+
         if (num_devices == 1) {
                 stripped |= BTRFS_BLOCK_GROUP_DUP;
                 stripped = flags & ~stripped;
@@ -8247,7 +8291,6 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                         break;
                 if (ret != 0)
                         goto error;
-
                 leaf = path->nodes[0];
                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
                 cache = kzalloc(sizeof(*cache), GFP_NOFS);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index c1faded5fca0..66836d85763b 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -48,30 +48,34 @@ static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
                                          struct page **prepared_pages,
                                          struct iov_iter *i)
 {
-        size_t copied;
+        size_t copied = 0;
         int pg = 0;
         int offset = pos & (PAGE_CACHE_SIZE - 1);
+        int total_copied = 0;
 
         while (write_bytes > 0) {
                 size_t count = min_t(size_t,
                                      PAGE_CACHE_SIZE - offset, write_bytes);
                 struct page *page = prepared_pages[pg];
-again:
-                if (unlikely(iov_iter_fault_in_readable(i, count)))
-                        return -EFAULT;
-
-                /* Copy data from userspace to the current page */
-                copied = iov_iter_copy_from_user(page, i, offset, count);
+                /*
+                 * Copy data from userspace to the current page
+                 *
+                 * Disable pagefault to avoid recursive lock since
+                 * the pages are already locked
+                 */
+                pagefault_disable();
+                copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
+                pagefault_enable();
 
                 /* Flush processor's dcache for this page */
                 flush_dcache_page(page);
                 iov_iter_advance(i, copied);
                 write_bytes -= copied;
+                total_copied += copied;
 
+                /* Return to btrfs_file_aio_write to fault page */
                 if (unlikely(copied == 0)) {
-                        count = min_t(size_t, PAGE_CACHE_SIZE - offset,
-                                      iov_iter_single_seg_count(i));
-                        goto again;
+                        break;
                 }
 
                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
@@ -81,7 +85,7 @@ again:
                         offset = 0;
                 }
         }
-        return 0;
+        return total_copied;
 }
 
 /*
@@ -854,6 +858,8 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
         unsigned long last_index;
         int will_write;
         int buffered = 0;
+        int copied = 0;
+        int dirty_pages = 0;
 
         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
                       (file->f_flags & O_DIRECT));
@@ -970,7 +976,17 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                 WARN_ON(num_pages > nrptrs);
                 memset(pages, 0, sizeof(struct page *) * nrptrs);
 
-                ret = btrfs_delalloc_reserve_space(inode, write_bytes);
+                /*
+                 * Fault pages before locking them in prepare_pages
+                 * to avoid recursive lock
+                 */
+                if (unlikely(iov_iter_fault_in_readable(&i, write_bytes))) {
+                        ret = -EFAULT;
+                        goto out;
+                }
+
+                ret = btrfs_delalloc_reserve_space(inode,
+                                        num_pages << PAGE_CACHE_SHIFT);
                 if (ret)
                         goto out;
 
@@ -978,37 +994,49 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
                                     pos, first_index, last_index,
                                     write_bytes);
                 if (ret) {
-                        btrfs_delalloc_release_space(inode, write_bytes);
+                        btrfs_delalloc_release_space(inode,
+                                        num_pages << PAGE_CACHE_SHIFT);
                         goto out;
                 }
 
-                ret = btrfs_copy_from_user(pos, num_pages,
+                copied = btrfs_copy_from_user(pos, num_pages,
                                            write_bytes, pages, &i);
-                if (ret == 0) {
+                dirty_pages = (copied + PAGE_CACHE_SIZE - 1) >>
+                                        PAGE_CACHE_SHIFT;
+
+                if (num_pages > dirty_pages) {
+                        if (copied > 0)
+                                atomic_inc(
+                                        &BTRFS_I(inode)->outstanding_extents);
+                        btrfs_delalloc_release_space(inode,
+                                        (num_pages - dirty_pages) <<
+                                        PAGE_CACHE_SHIFT);
+                }
+
+                if (copied > 0) {
                         dirty_and_release_pages(NULL, root, file, pages,
-                                                num_pages, pos, write_bytes);
+                                                dirty_pages, pos, copied);
                 }
 
                 btrfs_drop_pages(pages, num_pages);
-                if (ret) {
-                        btrfs_delalloc_release_space(inode, write_bytes);
-                        goto out;
-                }
 
-                if (will_write) {
-                        filemap_fdatawrite_range(inode->i_mapping, pos,
-                                                 pos + write_bytes - 1);
-                } else {
-                        balance_dirty_pages_ratelimited_nr(inode->i_mapping,
-                                                           num_pages);
-                        if (num_pages <
-                            (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
-                                btrfs_btree_balance_dirty(root, 1);
-                        btrfs_throttle(root);
+                if (copied > 0) {
+                        if (will_write) {
+                                filemap_fdatawrite_range(inode->i_mapping, pos,
+                                                         pos + copied - 1);
+                        } else {
+                                balance_dirty_pages_ratelimited_nr(
+                                                        inode->i_mapping,
+                                                        dirty_pages);
+                                if (dirty_pages <
+                                (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
+                                        btrfs_btree_balance_dirty(root, 1);
+                                btrfs_throttle(root);
+                        }
                 }
 
-                pos += write_bytes;
-                num_written += write_bytes;
+                pos += copied;
+                num_written += copied;
 
                 cond_resched();
         }
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 22ee0dc2e6b8..60d684266959 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -290,7 +290,7 @@ int load_free_space_cache(struct btrfs_fs_info *fs_info,
                        (unsigned long long)BTRFS_I(inode)->generation,
                        (unsigned long long)generation,
                        (unsigned long long)block_group->key.objectid);
-                goto out;
+                goto free_cache;
         }
 
         if (!num_entries)
@@ -524,6 +524,12 @@ int btrfs_write_out_cache(struct btrfs_root *root,
                 return 0;
         }
 
+        node = rb_first(&block_group->free_space_offset);
+        if (!node) {
+                iput(inode);
+                return 0;
+        }
+
         last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
         filemap_write_and_wait(inode->i_mapping);
         btrfs_wait_ordered_range(inode, inode->i_size &
@@ -543,10 +549,6 @@ int btrfs_write_out_cache(struct btrfs_root *root,
          */
         first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
 
-        node = rb_first(&block_group->free_space_offset);
-        if (!node)
-                goto out_free;
-
         /*
          * Lock all pages first so we can lock the extent safely.
          *
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8039390bd6a6..72f31ecb5c90 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -495,7 +495,7 @@ again:
                 add_async_extent(async_cow, start, num_bytes,
                                  total_compressed, pages, nr_pages_ret);
 
-                if (start + num_bytes < end && start + num_bytes < actual_end) {
+                if (start + num_bytes < end) {
                         start += num_bytes;
                         pages = NULL;
                         cond_resched();
@@ -5712,9 +5712,9 @@ static void btrfs_end_dio_bio(struct bio *bio, int err)
 
         if (err) {
                 printk(KERN_ERR "btrfs direct IO failed ino %lu rw %lu "
-                      "disk_bytenr %lu len %u err no %d\n",
-                      dip->inode->i_ino, bio->bi_rw, bio->bi_sector,
-                      bio->bi_size, err);
+                      "sector %#Lx len %u err no %d\n",
+                      dip->inode->i_ino, bio->bi_rw,
+                      (unsigned long long)bio->bi_sector, bio->bi_size, err);
                 dip->errors = 1;
 
                 /*
@@ -5934,8 +5934,7 @@ free_ordered:
          */
         if (write) {
                 struct btrfs_ordered_extent *ordered;
-                ordered = btrfs_lookup_ordered_extent(inode,
-                                                      dip->logical_offset);
+                ordered = btrfs_lookup_ordered_extent(inode, file_offset);
                 if (!test_bit(BTRFS_ORDERED_PREALLOC, &ordered->flags) &&
                     !test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags))
                         btrfs_free_reserved_extent(root, ordered->start,
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f1c9bb4079ed..f87552a1d7ea 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -947,23 +947,42 @@ out:
 
 static noinline int btrfs_ioctl_snap_create(struct file *file,
                                             void __user *arg, int subvol,
-                                            int async)
+                                            int v2)
 {
         struct btrfs_ioctl_vol_args *vol_args = NULL;
-        struct btrfs_ioctl_async_vol_args *async_vol_args = NULL;
+        struct btrfs_ioctl_vol_args_v2 *vol_args_v2 = NULL;
         char *name;
         u64 fd;
-        u64 transid = 0;
         int ret;
 
-        if (async) {
-                async_vol_args = memdup_user(arg, sizeof(*async_vol_args));
-                if (IS_ERR(async_vol_args))
-                        return PTR_ERR(async_vol_args);
+        if (v2) {
+                u64 transid = 0;
+                u64 *ptr = NULL;
 
-                name = async_vol_args->name;
-                fd = async_vol_args->fd;
-                async_vol_args->name[BTRFS_SNAPSHOT_NAME_MAX] = '\0';
+                vol_args_v2 = memdup_user(arg, sizeof(*vol_args_v2));
+                if (IS_ERR(vol_args_v2))
+                        return PTR_ERR(vol_args_v2);
+
+                if (vol_args_v2->flags & ~BTRFS_SUBVOL_CREATE_ASYNC) {
+                        ret = -EINVAL;
+                        goto out;
+                }
+
+                name = vol_args_v2->name;
+                fd = vol_args_v2->fd;
+                vol_args_v2->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
+
+                if (vol_args_v2->flags & BTRFS_SUBVOL_CREATE_ASYNC)
+                        ptr = &transid;
+
+                ret = btrfs_ioctl_snap_create_transid(file, name, fd,
+                                                      subvol, ptr);
+
+                if (ret == 0 && ptr &&
+                    copy_to_user(arg +
+                                 offsetof(struct btrfs_ioctl_vol_args_v2,
+                                          transid), ptr, sizeof(*ptr)))
+                        ret = -EFAULT;
         } else {
                 vol_args = memdup_user(arg, sizeof(*vol_args));
                 if (IS_ERR(vol_args))
@@ -971,20 +990,13 @@ static noinline int btrfs_ioctl_snap_create(struct file *file,
                 name = vol_args->name;
                 fd = vol_args->fd;
                 vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
-        }
-
-        ret = btrfs_ioctl_snap_create_transid(file, name, fd,
-                                              subvol, &transid);
 
-        if (!ret && async) {
-                if (copy_to_user(arg +
-                                offsetof(struct btrfs_ioctl_async_vol_args,
-                                transid), &transid, sizeof(transid)))
-                        return -EFAULT;
+                ret = btrfs_ioctl_snap_create_transid(file, name, fd,
+                                                      subvol, NULL);
         }
-
+out:
         kfree(vol_args);
-        kfree(async_vol_args);
+        kfree(vol_args_v2);
 
         return ret;
 }
@@ -2246,7 +2258,7 @@ long btrfs_ioctl(struct file *file, unsigned int
                 return btrfs_ioctl_getversion(file, argp);
         case BTRFS_IOC_SNAP_CREATE:
                 return btrfs_ioctl_snap_create(file, argp, 0, 0);
-        case BTRFS_IOC_SNAP_CREATE_ASYNC:
+        case BTRFS_IOC_SNAP_CREATE_V2:
                 return btrfs_ioctl_snap_create(file, argp, 0, 1);
         case BTRFS_IOC_SUBVOL_CREATE:
                 return btrfs_ioctl_snap_create(file, argp, 1, 0);
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index 17c99ebdf960..c344d12c646b 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -30,11 +30,15 @@ struct btrfs_ioctl_vol_args {
         char name[BTRFS_PATH_NAME_MAX + 1];
 };
 
-#define BTRFS_SNAPSHOT_NAME_MAX 4079
-struct btrfs_ioctl_async_vol_args {
+#define BTRFS_SUBVOL_CREATE_ASYNC       (1ULL << 0)
+
+#define BTRFS_SUBVOL_NAME_MAX 4039
+struct btrfs_ioctl_vol_args_v2 {
         __s64 fd;
         __u64 transid;
-        char name[BTRFS_SNAPSHOT_NAME_MAX + 1];
+        __u64 flags;
+        __u64 unused[4];
+        char name[BTRFS_SUBVOL_NAME_MAX + 1];
 };
 
 #define BTRFS_INO_LOOKUP_PATH_MAX 4080
@@ -187,6 +191,6 @@ struct btrfs_ioctl_space_args {
                                     struct btrfs_ioctl_space_args)
 #define BTRFS_IOC_START_SYNC _IOR(BTRFS_IOCTL_MAGIC, 24, __u64)
 #define BTRFS_IOC_WAIT_SYNC  _IOW(BTRFS_IOCTL_MAGIC, 22, __u64)
-#define BTRFS_IOC_SNAP_CREATE_ASYNC _IOW(BTRFS_IOCTL_MAGIC, 23, \
-                                   struct btrfs_ioctl_async_vol_args)
+#define BTRFS_IOC_SNAP_CREATE_V2 _IOW(BTRFS_IOCTL_MAGIC, 23, \
+                                   struct btrfs_ioctl_vol_args_v2)
 #endif
diff --git a/fs/btrfs/orphan.c b/fs/btrfs/orphan.c
index 79cba5fbc28e..f8be250963a0 100644
--- a/fs/btrfs/orphan.c
+++ b/fs/btrfs/orphan.c
@@ -56,8 +56,12 @@ int btrfs_del_orphan_item(struct btrfs_trans_handle *trans,
                 return -ENOMEM;
 
         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
-        if (ret)
+        if (ret < 0)
                 goto out;
+        if (ret) {
+                ret = -ENOENT;
+                goto out;
+        }
 
         ret = btrfs_del_item(trans, root, path);
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index dbb51ea7a13c..883c6fa1367e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -685,9 +685,9 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
                 mutex_unlock(&root->d_inode->i_mutex);
 
                 if (IS_ERR(new_root)) {
+                        dput(root);
                         deactivate_locked_super(s);
                         error = PTR_ERR(new_root);
-                        dput(root);
                         goto error_free_subvol_name;
                 }
                 if (!new_root->d_inode) {
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index cc04dc1445d6..6b9884507837 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -412,12 +412,16 @@ static noinline int device_list_add(const char *path,
 
                 device->fs_devices = fs_devices;
                 fs_devices->num_devices++;
-        } else if (strcmp(device->name, path)) {
+        } else if (!device->name || strcmp(device->name, path)) {
                 name = kstrdup(path, GFP_NOFS);
                 if (!name)
                         return -ENOMEM;
                 kfree(device->name);
                 device->name = name;
+                if (device->missing) {
+                        fs_devices->missing_devices--;
+                        device->missing = 0;
+                }
         }
 
         if (found_transid > fs_devices->latest_trans) {
@@ -1236,6 +1240,9 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 
         device->fs_devices->num_devices--;
 
+        if (device->missing)
+                root->fs_info->fs_devices->missing_devices--;
+
         next_device = list_entry(root->fs_info->fs_devices->devices.next,
                                  struct btrfs_device, dev_list);
         if (device->bdev == root->fs_info->sb->s_bdev)
@@ -3080,7 +3087,9 @@ static struct btrfs_device *add_missing_dev(struct btrfs_root *root,
         device->devid = devid;
         device->work.func = pending_bios_fn;
         device->fs_devices = fs_devices;
+        device->missing = 1;
         fs_devices->num_devices++;
+        fs_devices->missing_devices++;
         spin_lock_init(&device->io_lock);
         INIT_LIST_HEAD(&device->dev_alloc_list);
         memcpy(device->uuid, dev_uuid, BTRFS_UUID_SIZE);
@@ -3278,6 +3287,15 @@ static int read_one_dev(struct btrfs_root *root,
                         device = add_missing_dev(root, devid, dev_uuid);
                         if (!device)
                                 return -ENOMEM;
+                } else if (!device->missing) {
+                        /*
+                         * this happens when a device that was properly setup
+                         * in the device info lists suddenly goes bad.
+                         * device->bdev is NULL, and so we have to set
+                         * device->missing to one here
+                         */
+                        root->fs_info->fs_devices->missing_devices++;
+                        device->missing = 1;
                 }
         }
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 2b638b6e4eea..2740db49eb04 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -44,6 +44,7 @@ struct btrfs_device {
 
         int writeable;
         int in_fs_metadata;
+        int missing;
 
         spinlock_t io_lock;
 
@@ -93,6 +94,7 @@ struct btrfs_fs_devices {
         u64 num_devices;
         u64 open_devices;
         u64 rw_devices;
+        u64 missing_devices;
         u64 total_rw_bytes;
         struct block_device *latest_bdev;