Merge branch 'misc-for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.5

22 files changed, 186 insertions, 144 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 0ef5cc13fae2..61205e3bbefa 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -192,6 +192,10 @@ struct btrfs_inode {
         /* File creation time. */
         struct timespec i_otime;
 
+        /* Hook into fs_info->delayed_iputs */
+        struct list_head delayed_iput;
+        long delayed_iput_count;
+
         struct inode vfs_inode;
 };
 
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 5b8e235c4b6d..be1be0422ff4 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2248,7 +2248,6 @@ static void reada_for_search(struct btrfs_root *root,
         u64 target;
         u64 nread = 0;
         u64 gen;
-        int direction = path->reada;
         struct extent_buffer *eb;
         u32 nr;
         u32 blocksize;
@@ -2276,16 +2275,16 @@ static void reada_for_search(struct btrfs_root *root,
         nr = slot;
 
         while (1) {
-                if (direction < 0) {
+                if (path->reada == READA_BACK) {
                         if (nr == 0)
                                 break;
                         nr--;
-                } else if (direction > 0) {
+                } else if (path->reada == READA_FORWARD) {
                         nr++;
                         if (nr >= nritems)
                                 break;
                 }
-                if (path->reada < 0 && objectid) {
+                if (path->reada == READA_BACK && objectid) {
                         btrfs_node_key(node, &disk_key, nr);
                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
                                 break;
@@ -2493,7 +2492,7 @@ read_block_for_search(struct btrfs_trans_handle *trans,
         btrfs_set_path_blocking(p);
 
         free_extent_buffer(tmp);
-        if (p->reada)
+        if (p->reada != READA_NONE)
                 reada_for_search(root, p, level, slot, key->objectid);
 
         btrfs_release_path(p);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9a88d0c69be4..70c940582482 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -177,7 +177,7 @@ struct btrfs_ordered_sum;
 /* csum types */
 #define BTRFS_CSUM_TYPE_CRC32   0
 
-static int btrfs_csum_sizes[] = { 4 };
+static const int btrfs_csum_sizes[] = { 4 };
 
 /* four bytes for CRC32 */
 #define BTRFS_EMPTY_DIR_SIZE 0
@@ -598,14 +598,15 @@ struct btrfs_node {
  * The slots array records the index of the item or block pointer
  * used while walking the tree.
  */
+enum { READA_NONE = 0, READA_BACK, READA_FORWARD };
 struct btrfs_path {
         struct extent_buffer *nodes[BTRFS_MAX_LEVEL];
         int slots[BTRFS_MAX_LEVEL];
         /* if there is real range locking, this locks field will change */
-        int locks[BTRFS_MAX_LEVEL];
-        int reada;
+        u8 locks[BTRFS_MAX_LEVEL];
+        u8 reada;
         /* keep some upper locks as we walk down */
-        int lowest_level;
+        u8 lowest_level;
 
         /*
          * set by btrfs_split_item, tells search_slot to keep all locks
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index e06dd75ad13f..914ac13bd92f 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -493,12 +493,12 @@ update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
                                 memcpy(&existing_ref->extent_op->key,
                                        &ref->extent_op->key,
                                        sizeof(ref->extent_op->key));
-                                existing_ref->extent_op->update_key = 1;
+                                existing_ref->extent_op->update_key = true;
                         }
                         if (ref->extent_op->update_flags) {
                                 existing_ref->extent_op->flags_to_set |=
                                         ref->extent_op->flags_to_set;
-                                existing_ref->extent_op->update_flags = 1;
+                                existing_ref->extent_op->update_flags = true;
                         }
                         btrfs_free_delayed_extent_op(ref->extent_op);
                 }
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index 00ed02cbf3e9..c24b653c7343 100644
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -75,11 +75,11 @@ struct btrfs_delayed_ref_node {
 
 struct btrfs_delayed_extent_op {
         struct btrfs_disk_key key;
+        u8 level;
+        bool update_key;
+        bool update_flags;
+        bool is_data;
         u64 flags_to_set;
-        int level;
-        unsigned int update_key:1;
-        unsigned int update_flags:1;
-        unsigned int is_data:1;
 };
 
 /*
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index dc6b73a95342..c94457fde64d 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2682,6 +2682,7 @@ int open_ctree(struct super_block *sb,
         if (btrfs_check_super_csum(bh->b_data)) {
                 printk(KERN_ERR "BTRFS: superblock checksum mismatch\n");
                 err = -EINVAL;
+                brelse(bh);
                 goto fail_alloc;
         }
 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index add4af641cfa..46a39336e3d6 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -437,7 +437,7 @@ static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl)
          */
         path->skip_locking = 1;
         path->search_commit_root = 1;
-        path->reada = 1;
+        path->reada = READA_FORWARD;
 
         key.objectid = last;
         key.offset = 0;
@@ -2131,7 +2131,7 @@ static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
         if (!path)
                 return -ENOMEM;
 
-        path->reada = 1;
+        path->reada = READA_FORWARD;
         path->leave_spinning = 1;
         /* this will setup the path even if it fails to insert the back ref */
         ret = insert_inline_extent_backref(trans, fs_info->extent_root, path,
@@ -2157,7 +2157,7 @@ static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
         btrfs_mark_buffer_dirty(leaf);
         btrfs_release_path(path);
 
-        path->reada = 1;
+        path->reada = READA_FORWARD;
         path->leave_spinning = 1;
         /* now insert the actual backref */
         ret = insert_extent_backref(trans, root->fs_info->extent_root,
@@ -2270,7 +2270,7 @@ static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
         }
 
 again:
-        path->reada = 1;
+        path->reada = READA_FORWARD;
         path->leave_spinning = 1;
         ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key,
                                 path, 0, 1);
@@ -3007,9 +3007,9 @@ int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
                 return -ENOMEM;
 
         extent_op->flags_to_set = flags;
-        extent_op->update_flags = 1;
-        extent_op->update_key = 0;
-        extent_op->is_data = is_data ? 1 : 0;
+        extent_op->update_flags = true;
+        extent_op->update_key = false;
+        extent_op->is_data = is_data ? true : false;
         extent_op->level = level;
 
         ret = btrfs_add_delayed_extent_op(root->fs_info, trans, bytenr,
@@ -6472,7 +6472,7 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
         if (!path)
                 return -ENOMEM;
 
-        path->reada = 1;
+        path->reada = READA_FORWARD;
         path->leave_spinning = 1;
 
         is_data = owner_objectid >= BTRFS_FIRST_FREE_OBJECTID;
@@ -8031,12 +8031,9 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
                 else
                         memset(&extent_op->key, 0, sizeof(extent_op->key));
                 extent_op->flags_to_set = flags;
-                if (skinny_metadata)
-                        extent_op->update_key = 0;
-                else
-                        extent_op->update_key = 1;
-                extent_op->update_flags = 1;
-                extent_op->is_data = 0;
+                extent_op->update_key = skinny_metadata ? false : true;
+                extent_op->update_flags = true;
+                extent_op->is_data = false;
                 extent_op->level = level;
 
                 ret = btrfs_add_delayed_tree_ref(root->fs_info, trans,
@@ -9745,7 +9742,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = 1;
+        path->reada = READA_FORWARD;
 
         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
         if (btrfs_test_opt(root, SPACE_CACHE) &&
diff --git a/fs/btrfs/extent-tree.h b/fs/btrfs/extent-tree.h
deleted file mode 100644
index e69de29bb2d1..000000000000
--- a/fs/btrfs/extent-tree.h
+++ /dev/null
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 58ece6558430..a67e1c828d0f 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -202,7 +202,7 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
         }
 
         if (bio->bi_iter.bi_size > PAGE_CACHE_SIZE * 8)
-                path->reada = 2;
+                path->reada = READA_FORWARD;
 
         WARN_ON(bio->bi_vcnt <= 0);
 
@@ -328,7 +328,7 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 
         if (search_commit) {
                 path->skip_locking = 1;
-                path->reada = 2;
+                path->reada = READA_FORWARD;
                 path->search_commit_root = 1;
         }
 
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 7c5992d0fd31..d468bfd3debc 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2016,7 +2016,7 @@ static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
         return true;
 }
 
-static struct btrfs_free_space_op free_space_op = {
+static const struct btrfs_free_space_op free_space_op = {
         .recalc_thresholds      = recalculate_thresholds,
         .use_bitmap             = use_bitmap,
 };
diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
index f251865eb6f3..33178c490ace 100644
--- a/fs/btrfs/free-space-cache.h
+++ b/fs/btrfs/free-space-cache.h
@@ -37,7 +37,7 @@ struct btrfs_free_space_ctl {
         int total_bitmaps;
         int unit;
         u64 start;
-        struct btrfs_free_space_op *op;
+        const struct btrfs_free_space_op *op;
         void *private;
         struct mutex cache_writeout_mutex;
         struct list_head trimming_ranges;
diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index 767a6056ac45..1951ad69382f 100644
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -48,7 +48,7 @@ static int caching_kthread(void *data)
         /* Since the commit root is read-only, we can safely skip locking. */
         path->skip_locking = 1;
         path->search_commit_root = 1;
-        path->reada = 2;
+        path->reada = READA_FORWARD;
 
         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
         key.offset = 0;
@@ -334,7 +334,7 @@ static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
         return true;
 }
 
-static struct btrfs_free_space_op free_ino_op = {
+static const struct btrfs_free_space_op free_ino_op = {
         .recalc_thresholds      = recalculate_thresholds,
         .use_bitmap             = use_bitmap,
 };
@@ -356,7 +356,7 @@ static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
         return false;
 }
 
-static struct btrfs_free_space_op pinned_free_ino_op = {
+static const struct btrfs_free_space_op pinned_free_ino_op = {
         .recalc_thresholds      = pinned_recalc_thresholds,
         .use_bitmap             = pinned_use_bitmap,
 };
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index bdb0008712c8..f09cf27245f9 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -81,17 +81,16 @@ static const struct inode_operations btrfs_file_inode_operations;
 static const struct address_space_operations btrfs_aops;
 static const struct address_space_operations btrfs_symlink_aops;
 static const struct file_operations btrfs_dir_file_operations;
-static struct extent_io_ops btrfs_extent_io_ops;
+static const struct extent_io_ops btrfs_extent_io_ops;
 
 static struct kmem_cache *btrfs_inode_cachep;
-static struct kmem_cache *btrfs_delalloc_work_cachep;
 struct kmem_cache *btrfs_trans_handle_cachep;
 struct kmem_cache *btrfs_transaction_cachep;
 struct kmem_cache *btrfs_path_cachep;
 struct kmem_cache *btrfs_free_space_cachep;
 
 #define S_SHIFT 12
-static unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = {
+static const unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = {
         [S_IFREG >> S_SHIFT]    = BTRFS_FT_REG_FILE,
         [S_IFDIR >> S_SHIFT]    = BTRFS_FT_DIR,
         [S_IFCHR >> S_SHIFT]    = BTRFS_FT_CHRDEV,
@@ -3113,55 +3112,47 @@ static int btrfs_readpage_end_io_hook(struct btrfs_io_bio *io_bio,
                                       start, (size_t)(end - start + 1));
 }
 
-struct delayed_iput {
-        struct list_head list;
-        struct inode *inode;
-};
-
-/* JDM: If this is fs-wide, why can't we add a pointer to
- * btrfs_inode instead and avoid the allocation? */
 void btrfs_add_delayed_iput(struct inode *inode)
 {
         struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
-        struct delayed_iput *delayed;
+        struct btrfs_inode *binode = BTRFS_I(inode);
 
         if (atomic_add_unless(&inode->i_count, -1, 1))
                 return;
 
-        delayed = kmalloc(sizeof(*delayed), GFP_NOFS | __GFP_NOFAIL);
-        delayed->inode = inode;
-
         spin_lock(&fs_info->delayed_iput_lock);
-        list_add_tail(&delayed->list, &fs_info->delayed_iputs);
+        if (binode->delayed_iput_count == 0) {
+                ASSERT(list_empty(&binode->delayed_iput));
+                list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs);
+        } else {
+                binode->delayed_iput_count++;
+        }
         spin_unlock(&fs_info->delayed_iput_lock);
 }
 
 void btrfs_run_delayed_iputs(struct btrfs_root *root)
 {
-        LIST_HEAD(list);
         struct btrfs_fs_info *fs_info = root->fs_info;
-        struct delayed_iput *delayed;
-        int empty;
-
-        spin_lock(&fs_info->delayed_iput_lock);
-        empty = list_empty(&fs_info->delayed_iputs);
-        spin_unlock(&fs_info->delayed_iput_lock);
-        if (empty)
-                return;
 
         down_read(&fs_info->delayed_iput_sem);
-
         spin_lock(&fs_info->delayed_iput_lock);
-        list_splice_init(&fs_info->delayed_iputs, &list);
-        spin_unlock(&fs_info->delayed_iput_lock);
-
-        while (!list_empty(&list)) {
-                delayed = list_entry(list.next, struct delayed_iput, list);
-                list_del(&delayed->list);
-                iput(delayed->inode);
-                kfree(delayed);
+        while (!list_empty(&fs_info->delayed_iputs)) {
+                struct btrfs_inode *inode;
+
+                inode = list_first_entry(&fs_info->delayed_iputs,
+                                struct btrfs_inode, delayed_iput);
+                if (inode->delayed_iput_count) {
+                        inode->delayed_iput_count--;
+                        list_move_tail(&inode->delayed_iput,
+                                        &fs_info->delayed_iputs);
+                } else {
+                        list_del_init(&inode->delayed_iput);
+                }
+                spin_unlock(&fs_info->delayed_iput_lock);
+                iput(&inode->vfs_inode);
+                spin_lock(&fs_info->delayed_iput_lock);
         }
-
+        spin_unlock(&fs_info->delayed_iput_lock);
         up_read(&root->fs_info->delayed_iput_sem);
 }
 
@@ -3358,7 +3349,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root)
                 ret = -ENOMEM;
                 goto out;
         }
-        path->reada = -1;
+        path->reada = READA_BACK;
 
         key.objectid = BTRFS_ORPHAN_OBJECTID;
         key.type = BTRFS_ORPHAN_ITEM_KEY;
@@ -4324,7 +4315,7 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = -1;
+        path->reada = READA_BACK;
 
         /*
          * We want to drop from the next block forward in case this new size is
@@ -5760,7 +5751,7 @@ static int btrfs_real_readdir(struct file *file, struct dir_context *ctx)
         if (!path)
                 return -ENOMEM;
 
-        path->reada = 1;
+        path->reada = READA_FORWARD;
 
         if (key_type == BTRFS_DIR_INDEX_KEY) {
                 INIT_LIST_HEAD(&ins_list);
@@ -6791,7 +6782,7 @@ again:
                  * Chances are we'll be called again, so go ahead and do
                  * readahead
                  */
-                path->reada = 1;
+                path->reada = READA_FORWARD;
         }
 
         ret = btrfs_lookup_file_extent(trans, root, path,
@@ -8563,15 +8554,28 @@ int btrfs_readpage(struct file *file, struct page *page)
 static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 {
         struct extent_io_tree *tree;
-
+        struct inode *inode = page->mapping->host;
+        int ret;
 
         if (current->flags & PF_MEMALLOC) {
                 redirty_page_for_writepage(wbc, page);
                 unlock_page(page);
                 return 0;
         }
+
+        /*
+         * If we are under memory pressure we will call this directly from the
+         * VM, we need to make sure we have the inode referenced for the ordered
+         * extent.  If not just return like we didn't do anything.
+         */
+        if (!igrab(inode)) {
+                redirty_page_for_writepage(wbc, page);
+                return AOP_WRITEPAGE_ACTIVATE;
+        }
         tree = &BTRFS_I(page->mapping->host)->io_tree;
-        return extent_write_full_page(tree, page, btrfs_get_extent, wbc);
+        ret = extent_write_full_page(tree, page, btrfs_get_extent, wbc);
+        btrfs_add_delayed_iput(inode);
+        return ret;
 }
 
 static int btrfs_writepages(struct address_space *mapping,
@@ -9053,6 +9057,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
         ei->dir_index = 0;
         ei->last_unlink_trans = 0;
         ei->last_log_commit = 0;
+        ei->delayed_iput_count = 0;
 
         spin_lock_init(&ei->lock);
         ei->outstanding_extents = 0;
@@ -9077,6 +9082,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
         mutex_init(&ei->delalloc_mutex);
         btrfs_ordered_inode_tree_init(&ei->ordered_tree);
         INIT_LIST_HEAD(&ei->delalloc_inodes);
+        INIT_LIST_HEAD(&ei->delayed_iput);
         RB_CLEAR_NODE(&ei->rb_node);
 
         return inode;
@@ -9181,8 +9187,6 @@ void btrfs_destroy_cachep(void)
                 kmem_cache_destroy(btrfs_path_cachep);
         if (btrfs_free_space_cachep)
                 kmem_cache_destroy(btrfs_free_space_cachep);
-        if (btrfs_delalloc_work_cachep)
-                kmem_cache_destroy(btrfs_delalloc_work_cachep);
 }
 
 int btrfs_init_cachep(void)
@@ -9217,13 +9221,6 @@ int btrfs_init_cachep(void)
         if (!btrfs_free_space_cachep)
                 goto fail;
 
-        btrfs_delalloc_work_cachep = kmem_cache_create("btrfs_delalloc_work",
-                        sizeof(struct btrfs_delalloc_work), 0,
-                        SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
-                        NULL);
-        if (!btrfs_delalloc_work_cachep)
-                goto fail;
-
         return 0;
 fail:
         btrfs_destroy_cachep();
@@ -9464,7 +9461,7 @@ struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode,
 {
         struct btrfs_delalloc_work *work;
 
-        work = kmem_cache_zalloc(btrfs_delalloc_work_cachep, GFP_NOFS);
+        work = kmalloc(sizeof(*work), GFP_NOFS);
         if (!work)
                 return NULL;
 
@@ -9482,7 +9479,7 @@ struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode,
 void btrfs_wait_and_free_delalloc_work(struct btrfs_delalloc_work *work)
 {
         wait_for_completion(&work->completion);
-        kmem_cache_free(btrfs_delalloc_work_cachep, work);
+        kfree(work);
 }
 
 /*
@@ -10047,7 +10044,7 @@ static const struct file_operations btrfs_dir_file_operations = {
         .fsync          = btrfs_sync_file,
 };
 
-static struct extent_io_ops btrfs_extent_io_ops = {
+static const struct extent_io_ops btrfs_extent_io_ops = {
         .fill_delalloc = run_delalloc_range,
         .submit_bio_hook = btrfs_submit_bio_hook,
         .merge_bio_hook = btrfs_merge_bio_hook,
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8bbecdaf58a3..f8519b866c0a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -655,22 +655,28 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
                 return -EINVAL;
 
+        pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_NOFS);
+        if (!pending_snapshot)
+                return -ENOMEM;
+
+        pending_snapshot->root_item = kzalloc(sizeof(struct btrfs_root_item),
+                        GFP_NOFS);
+        pending_snapshot->path = btrfs_alloc_path();
+        if (!pending_snapshot->root_item || !pending_snapshot->path) {
+                ret = -ENOMEM;
+                goto free_pending;
+        }
+
         atomic_inc(&root->will_be_snapshoted);
         smp_mb__after_atomic();
         btrfs_wait_for_no_snapshoting_writes(root);
 
         ret = btrfs_start_delalloc_inodes(root, 0);
         if (ret)
-                goto out;
+                goto dec_and_free;
 
         btrfs_wait_ordered_extents(root, -1);
 
-        pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_NOFS);
-        if (!pending_snapshot) {
-                ret = -ENOMEM;
-                goto out;
-        }
-
         btrfs_init_block_rsv(&pending_snapshot->block_rsv,
                              BTRFS_BLOCK_RSV_TEMP);
         /*
@@ -686,7 +692,7 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
                                         &pending_snapshot->qgroup_reserved,
                                         false);
         if (ret)
-                goto free;
+                goto dec_and_free;
 
         pending_snapshot->dentry = dentry;
         pending_snapshot->root = root;
@@ -737,11 +743,14 @@ fail:
         btrfs_subvolume_release_metadata(BTRFS_I(dir)->root,
                                          &pending_snapshot->block_rsv,
                                          pending_snapshot->qgroup_reserved);
-free:
-        kfree(pending_snapshot);
-out:
+dec_and_free:
         if (atomic_dec_and_test(&root->will_be_snapshoted))
                 wake_up_atomic_t(&root->will_be_snapshoted);
+free_pending:
+        kfree(pending_snapshot->root_item);
+        btrfs_free_path(pending_snapshot->path);
+        kfree(pending_snapshot);
+
         return ret;
 }
 
@@ -3478,7 +3487,7 @@ static int btrfs_clone(struct inode *src, struct inode *inode,
                 return ret;
         }
 
-        path->reada = 2;
+        path->reada = READA_FORWARD;
         /* clone data */
         key.objectid = btrfs_ino(src);
         key.type = BTRFS_EXTENT_DATA_KEY;
@@ -5286,7 +5295,7 @@ out_unlock:
 static int btrfs_ioctl_get_supported_features(struct file *file,
                                               void __user *arg)
 {
-        static struct btrfs_ioctl_feature_flags features[3] = {
+        static const struct btrfs_ioctl_feature_flags features[3] = {
                 INIT_FEATURE_FLAGS(SUPP),
                 INIT_FEATURE_FLAGS(SAFE_SET),
                 INIT_FEATURE_FLAGS(SAFE_CLEAR)
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index b4ca5454ef1a..ef6d8fc85853 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -708,8 +708,8 @@ struct backref_node *build_backref_tree(struct reloc_control *rc,
                 err = -ENOMEM;
                 goto out;
         }
-        path1->reada = 1;
-        path2->reada = 2;
+        path1->reada = READA_FORWARD;
+        path2->reada = READA_FORWARD;
 
         node = alloc_backref_node(cache);
         if (!node) {
@@ -2130,7 +2130,7 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = 1;
+        path->reada = READA_FORWARD;
 
         reloc_root = root->reloc_root;
         root_item = &reloc_root->root_item;
@@ -3527,7 +3527,7 @@ static int find_data_references(struct reloc_control *rc,
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = 1;
+        path->reada = READA_FORWARD;
 
         root = read_fs_root(rc->extent_root->fs_info, ref_root);
         if (IS_ERR(root)) {
@@ -3917,7 +3917,7 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = 1;
+        path->reada = READA_FORWARD;
 
         ret = prepare_to_relocate(rc);
         if (ret) {
@@ -4343,7 +4343,7 @@ int btrfs_recover_relocation(struct btrfs_root *root)
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = -1;
+        path->reada = READA_BACK;
 
         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
         key.type = BTRFS_ROOT_ITEM_KEY;
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 69987150ddfa..dbfbfb3b86b5 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3507,7 +3507,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
         if (!path)
                 return -ENOMEM;
 
-        path->reada = 2;
+        path->reada = READA_FORWARD;
         path->search_commit_root = 1;
         path->skip_locking = 1;
 
@@ -3735,27 +3735,27 @@ static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
         if (fs_info->scrub_workers_refcnt == 0) {
                 if (is_dev_replace)
                         fs_info->scrub_workers =
-                                btrfs_alloc_workqueue("btrfs-scrub", flags,
+                                btrfs_alloc_workqueue("scrub", flags,
                                                       1, 4);
                 else
                         fs_info->scrub_workers =
-                                btrfs_alloc_workqueue("btrfs-scrub", flags,
+                                btrfs_alloc_workqueue("scrub", flags,
                                                       max_active, 4);
                 if (!fs_info->scrub_workers)
                         goto fail_scrub_workers;
 
                 fs_info->scrub_wr_completion_workers =
-                        btrfs_alloc_workqueue("btrfs-scrubwrc", flags,
+                        btrfs_alloc_workqueue("scrubwrc", flags,
                                               max_active, 2);
                 if (!fs_info->scrub_wr_completion_workers)
                         goto fail_scrub_wr_completion_workers;
 
                 fs_info->scrub_nocow_workers =
-                        btrfs_alloc_workqueue("btrfs-scrubnc", flags, 1, 0);
+                        btrfs_alloc_workqueue("scrubnc", flags, 1, 0);
                 if (!fs_info->scrub_nocow_workers)
                         goto fail_scrub_nocow_workers;
                 fs_info->scrub_parity_workers =
-                        btrfs_alloc_workqueue("btrfs-scrubparity", flags,
+                        btrfs_alloc_workqueue("scrubparity", flags,
                                               max_active, 2);
                 if (!fs_info->scrub_parity_workers)
                         goto fail_scrub_parity_workers;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 9153d54d27c8..ff15087052f5 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -310,7 +310,7 @@ enum {
         Opt_err,
 };
 
-static match_table_t tokens = {
+static const match_table_t tokens = {
         {Opt_degraded, "degraded"},
         {Opt_subvol, "subvol=%s"},
         {Opt_subvolid, "subvolid=%s"},
@@ -1991,6 +1991,8 @@ static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
  * there are other factors that may change the result (like a new metadata
  * chunk).
  *
+ * If metadata is exhausted, f_bavail will be 0.
+ *
  * FIXME: not accurate for mixed block groups, total and free/used are ok,
  * available appears slightly larger.
  */
@@ -2002,11 +2004,13 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
         struct btrfs_space_info *found;
         u64 total_used = 0;
         u64 total_free_data = 0;
+        u64 total_free_meta = 0;
         int bits = dentry->d_sb->s_blocksize_bits;
         __be32 *fsid = (__be32 *)fs_info->fsid;
         unsigned factor = 1;
         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
         int ret;
+        u64 thresh = 0;
 
         /*
          * holding chunk_muext to avoid allocating new chunks, holding
@@ -2032,6 +2036,8 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
                                 }
                         }
                 }
+                if (found->flags & BTRFS_BLOCK_GROUP_METADATA)
+                        total_free_meta += found->disk_total - found->disk_used;
 
                 total_used += found->disk_used;
         }
@@ -2054,6 +2060,24 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
         buf->f_bavail += div_u64(total_free_data, factor);
         buf->f_bavail = buf->f_bavail >> bits;
 
+        /*
+         * We calculate the remaining metadata space minus global reserve. If
+         * this is (supposedly) smaller than zero, there's no space. But this
+         * does not hold in practice, the exhausted state happens where's still
+         * some positive delta. So we apply some guesswork and compare the
+         * delta to a 4M threshold.  (Practically observed delta was ~2M.)
+         *
+         * We probably cannot calculate the exact threshold value because this
+         * depends on the internal reservations requested by various
+         * operations, so some operations that consume a few metadata will
+         * succeed even if the Avail is zero. But this is better than the other
+         * way around.
+         */
+        thresh = 4 * 1024 * 1024;
+
+        if (total_free_meta - thresh < block_rsv->size)
+                buf->f_bavail = 0;
+
         buf->f_type = BTRFS_SUPER_MAGIC;
         buf->f_bsize = dentry->d_sb->s_blocksize;
         buf->f_namelen = BTRFS_NAME_LEN;
diff --git a/fs/btrfs/tests/free-space-tests.c b/fs/btrfs/tests/free-space-tests.c
index cd3e300b9ba5..e37d55ecdf1f 100644
--- a/fs/btrfs/tests/free-space-tests.c
+++ b/fs/btrfs/tests/free-space-tests.c
@@ -410,9 +410,11 @@ test_steal_space_from_bitmap_to_extent(struct btrfs_block_group_cache *cache)
         int ret;
         u64 offset;
         u64 max_extent_size;
-
-        bool (*use_bitmap_op)(struct btrfs_free_space_ctl *,
-                              struct btrfs_free_space *);
+        const struct btrfs_free_space_op test_free_space_ops = {
+                .recalc_thresholds = cache->free_space_ctl->op->recalc_thresholds,
+                .use_bitmap = test_use_bitmap,
+        };
+        const struct btrfs_free_space_op *orig_free_space_ops;
 
         test_msg("Running space stealing from bitmap to extent\n");
 
@@ -434,8 +436,8 @@ test_steal_space_from_bitmap_to_extent(struct btrfs_block_group_cache *cache)
          * that forces use of bitmaps as soon as we have at least 1
          * extent entry.
          */
-        use_bitmap_op = cache->free_space_ctl->op->use_bitmap;
-        cache->free_space_ctl->op->use_bitmap = test_use_bitmap;
+        orig_free_space_ops = cache->free_space_ctl->op;
+        cache->free_space_ctl->op = &test_free_space_ops;
 
         /*
          * Extent entry covering free space range [128Mb - 256Kb, 128Mb - 128Kb[
@@ -842,7 +844,7 @@ test_steal_space_from_bitmap_to_extent(struct btrfs_block_group_cache *cache)
         if (ret)
                 return ret;
 
-        cache->free_space_ctl->op->use_bitmap = use_bitmap_op;
+        cache->free_space_ctl->op = orig_free_space_ops;
         __btrfs_remove_free_space_cache(cache->free_space_ctl);
 
         return 0;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index f85ccf634ca1..34961f02e58c 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1336,17 +1336,11 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         u64 root_flags;
         uuid_le new_uuid;
 
-        path = btrfs_alloc_path();
-        if (!path) {
-                pending->error = -ENOMEM;
-                return 0;
-        }
+        ASSERT(pending->path);
+        path = pending->path;
 
-        new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
-        if (!new_root_item) {
-                pending->error = -ENOMEM;
-                goto root_item_alloc_fail;
-        }
+        ASSERT(pending->root_item);
+        new_root_item = pending->root_item;
 
         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
         if (pending->error)
@@ -1579,8 +1573,10 @@ clear_skip_qgroup:
         btrfs_clear_skip_qgroup(trans);
 no_free_objectid:
         kfree(new_root_item);
-root_item_alloc_fail:
+        pending->root_item = NULL;
         btrfs_free_path(path);
+        pending->path = NULL;
+
         return ret;
 }
 
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 64c8221b6165..72be51f7ca2f 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -137,8 +137,10 @@ struct btrfs_pending_snapshot {
         struct dentry *dentry;
         struct inode *dir;
         struct btrfs_root *root;
+        struct btrfs_root_item *root_item;
         struct btrfs_root *snap;
         struct btrfs_qgroup_inherit *inherit;
+        struct btrfs_path *path;
         /* block reservation for the operation */
         struct btrfs_block_rsv block_rsv;
         u64 qgroup_reserved;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a114b7bb87a0..2fa5ba814120 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1103,7 +1103,7 @@ int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = 2;
+        path->reada = READA_FORWARD;
 
         key.objectid = device->devid;
         key.offset = start;
@@ -1272,7 +1272,7 @@ again:
                 goto out;
         }
 
-        path->reada = 2;
+        path->reada = READA_FORWARD;
         path->search_commit_root = 1;
         path->skip_locking = 1;
 
@@ -3724,14 +3724,6 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
                 goto out;
         }
 
-        /* allow dup'ed data chunks only in mixed mode */
-        if (!mixed && (bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
-            (bctl->data.target & BTRFS_BLOCK_GROUP_DUP)) {
-                btrfs_err(fs_info, "dup for data is not allowed");
-                ret = -EINVAL;
-                goto out;
-        }
-
         /* allow to reduce meta or sys integrity only if force set */
         allowed = BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
                         BTRFS_BLOCK_GROUP_RAID10 |
@@ -3757,6 +3749,13 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
                 }
         } while (read_seqretry(&fs_info->profiles_lock, seq));
 
+        if (btrfs_get_num_tolerated_disk_barrier_failures(bctl->meta.target) <
+                btrfs_get_num_tolerated_disk_barrier_failures(bctl->data.target)) {
+                btrfs_warn(fs_info,
+        "metatdata profile 0x%llx has lower redundancy than data profile 0x%llx",
+                        bctl->meta.target, bctl->data.target);
+        }
+
         if (bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {
                 fs_info->num_tolerated_disk_barrier_failures = min(
                         btrfs_calc_num_tolerated_disk_barrier_failures(fs_info),
@@ -4269,7 +4268,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
         if (!path)
                 return -ENOMEM;
 
-        path->reada = 2;
+        path->reada = READA_FORWARD;
 
         lock_chunks(root);
 
@@ -6526,6 +6525,14 @@ int btrfs_read_sys_array(struct btrfs_root *root)
                                 goto out_short_read;
 
                         num_stripes = btrfs_chunk_num_stripes(sb, chunk);
+                        if (!num_stripes) {
+                                printk(KERN_ERR
+            "BTRFS: invalid number of stripes %u in sys_array at offset %u\n",
+                                        num_stripes, cur_offset);
+                                ret = -EIO;
+                                break;
+                        }
+
                         len = btrfs_chunk_item_size(num_stripes);
                         if (cur_offset + len > array_size)
                                 goto out_short_read;
@@ -6534,6 +6541,9 @@ int btrfs_read_sys_array(struct btrfs_root *root)
                         if (ret)
                                 break;
                 } else {
+                        printk(KERN_ERR
+                "BTRFS: unexpected item type %u in sys_array at offset %u\n",
+                                (u32)key.type, cur_offset);
                         ret = -EIO;
                         break;
                 }
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 24e8ff722730..608552ed89c0 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -283,7 +283,7 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
-        path->reada = 2;
+        path->reada = READA_FORWARD;
 
         /* search for our xattrs */
         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);