Btrfs: Implement basic support for -ENOSPC

This is intended to prevent accidentally filling the drive.  A determined
user can still make things oops.

It includes some accounting of the current bytes under delayed allocation,
but this will change as things get optimized

Signed-off-by: Chris Mason <chris.mason@oracle.com>

6 files changed, 193 insertions, 28 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2559f5d5d00a..10129cc6656f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -346,6 +346,8 @@ struct btrfs_fs_info {
         int closing;
 
         u64 total_pinned;
+        spinlock_t delalloc_lock;
+        u64 delalloc_bytes;
 };
 /*
  * in ram representation of the tree.  extent_root is used for all allocations
@@ -1115,6 +1117,8 @@ int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root, struct btrfs_path *path,
                         u64 isize);
 /* inode.c */
+int btrfs_check_free_space(struct btrfs_root *root, u64 num_required,
+                           int for_del);
 int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page);
 int btrfs_readpage(struct file *file, struct page *page);
 void btrfs_delete_inode(struct inode *inode);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index ebb2db624fdd..eebb4fb65c61 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -223,7 +223,8 @@ static int btree_writepages(struct address_space *mapping,
                 } else {
                         thresh = 8 * 1024 * 1024;
                 }
-                num_dirty = count_range_bits(tree, &start, thresh, EXTENT_DIRTY);
+                num_dirty = count_range_bits(tree, &start, (u64)-1,
+                                             thresh, EXTENT_DIRTY);
                 if (num_dirty < thresh) {
                         return 0;
                 }
@@ -559,6 +560,7 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         INIT_LIST_HEAD(&fs_info->dead_roots);
         INIT_LIST_HEAD(&fs_info->hashers);
         spin_lock_init(&fs_info->hash_lock);
+        spin_lock_init(&fs_info->delalloc_lock);
 
         memset(&fs_info->super_kobj, 0, sizeof(fs_info->super_kobj));
         init_completion(&fs_info->kobj_unregister);
@@ -570,6 +572,7 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         fs_info->sb = sb;
         fs_info->mount_opt = 0;
         fs_info->max_extent = (u64)-1;
+        fs_info->delalloc_bytes = 0;
         fs_info->btree_inode = new_inode(sb);
         fs_info->btree_inode->i_ino = 1;
         fs_info->btree_inode->i_nlink = 1;
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index a0dff34dd437..2b92f1070274 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -1131,7 +1131,8 @@ out:
 }
 
 u64 count_range_bits(struct extent_map_tree *tree,
-                     u64 *start, u64 max_bytes, unsigned long bits)
+                     u64 *start, u64 search_end, u64 max_bytes,
+                     unsigned long bits)
 {
         struct rb_node *node;
         struct extent_state *state;
@@ -1139,9 +1140,14 @@ u64 count_range_bits(struct extent_map_tree *tree,
         u64 total_bytes = 0;
         int found = 0;
 
+        if (search_end <= cur_start) {
+                printk("search_end %Lu start %Lu\n", search_end, cur_start);
+                WARN_ON(1);
+                return 0;
+        }
+
         write_lock_irq(&tree->lock);
-        if (bits == EXTENT_DIRTY) {
-                *start = 0;
+        if (cur_start == 0 && bits == EXTENT_DIRTY) {
                 total_bytes = tree->dirty_bytes;
                 goto out;
         }
@@ -1156,8 +1162,11 @@ u64 count_range_bits(struct extent_map_tree *tree,
 
         while(1) {
                 state = rb_entry(node, struct extent_state, rb_node);
-                if ((state->state & bits)) {
-                        total_bytes += state->end - state->start + 1;
+                if (state->start > search_end)
+                        break;
+                if (state->end >= cur_start && (state->state & bits)) {
+                        total_bytes += min(search_end, state->end) + 1 -
+                                       max(cur_start, state->start);
                         if (total_bytes >= max_bytes)
                                 break;
                         if (!found) {
@@ -1173,7 +1182,6 @@ out:
         write_unlock_irq(&tree->lock);
         return total_bytes;
 }
-
 /*
  * helper function to lock both pages and extents in the tree.
  * pages must be locked first.
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 6e572d3e8924..ea60f5447b5b 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -115,7 +115,8 @@ int __init extent_map_init(void);
 void extent_map_exit(void);
 
 u64 count_range_bits(struct extent_map_tree *tree,
-                     u64 *start, u64 max_bytes, unsigned long bits);
+                     u64 *start, u64 search_end,
+                     u64 max_bytes, unsigned long bits);
 
 int test_range_bit(struct extent_map_tree *tree, u64 start, u64 end,
                    int bits, int filled);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 461b09663fed..71dc2d33b6c6 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -307,6 +307,7 @@ static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
             inline_size > 32768 ||
             inline_size >= BTRFS_MAX_INLINE_DATA_SIZE(root)) {
                 u64 last_end;
+                u64 existing_delalloc = 0;
 
                 for (i = 0; i < num_pages; i++) {
                         struct page *p = pages[i];
@@ -316,8 +317,19 @@ static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                 last_end = (u64)(pages[num_pages -1]->index) <<
                                 PAGE_CACHE_SHIFT;
                 last_end += PAGE_CACHE_SIZE - 1;
+                if (start_pos < isize) {
+                        u64 delalloc_start = start_pos;
+                        existing_delalloc = count_range_bits(em_tree,
+                                             &delalloc_start,
+                                             end_of_last_block, (u64)-1,
+                                             EXTENT_DELALLOC);
+                }
                 set_extent_delalloc(em_tree, start_pos, end_of_last_block,
                                  GFP_NOFS);
+                spin_lock(&root->fs_info->delalloc_lock);
+                root->fs_info->delalloc_bytes += (end_of_last_block + 1 -
+                                          start_pos) - existing_delalloc;
+                spin_unlock(&root->fs_info->delalloc_lock);
         } else {
                 u64 aligned_end;
                 /* step one, delete the existing extents in this range */
@@ -708,12 +720,12 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
         current->backing_dev_info = inode->i_mapping->backing_dev_info;
         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
         if (err)
-                goto out;
+                goto out_nolock;
         if (count == 0)
-                goto out;
+                goto out_nolock;
         err = remove_suid(fdentry(file));
         if (err)
-                goto out;
+                goto out_nolock;
         file_update_time(file);
 
         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
@@ -758,6 +770,13 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 
                 WARN_ON(num_pages > nrptrs);
                 memset(pages, 0, sizeof(pages));
+
+                mutex_lock(&root->fs_info->fs_mutex);
+                ret = btrfs_check_free_space(root, write_bytes, 0);
+                mutex_unlock(&root->fs_info->fs_mutex);
+                if (ret)
+                        goto out;
+
                 ret = prepare_pages(root, file, pages, num_pages,
                                     pos, first_index, last_index,
                                     write_bytes);
@@ -787,8 +806,9 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                         btrfs_btree_balance_dirty(root, 1);
                 cond_resched();
         }
-        mutex_unlock(&inode->i_mutex);
 out:
+        mutex_unlock(&inode->i_mutex);
+out_nolock:
         kfree(pages);
         if (pinned[0])
                 page_cache_release(pinned[0]);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1c61c85dc3d8..a9f5d6d417f0 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -72,6 +72,26 @@ static unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = {
         [S_IFLNK >> S_SHIFT]    = BTRFS_FT_SYMLINK,
 };
 
+int btrfs_check_free_space(struct btrfs_root *root, u64 num_required,
+                           int for_del)
+{
+        u64 total = btrfs_super_total_bytes(&root->fs_info->super_copy);
+        u64 used = btrfs_super_bytes_used(&root->fs_info->super_copy);
+        u64 thresh;
+        int ret = 0;
+
+        if (for_del)
+                thresh = (total * 90) / 100;
+        else
+                thresh = (total * 85) / 100;
+
+        spin_lock(&root->fs_info->delalloc_lock);
+        if (used + root->fs_info->delalloc_bytes + num_required > thresh)
+                ret = -ENOSPC;
+        spin_unlock(&root->fs_info->delalloc_lock);
+        return ret;
+}
+
 static int cow_file_range(struct inode *inode, u64 start, u64 end)
 {
         struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -124,6 +144,7 @@ static int run_delalloc_nocow(struct inode *inode, u64 start, u64 end)
         u64 extent_end;
         u64 bytenr;
         u64 cow_end;
+        u64 loops = 0;
         struct btrfs_root *root = BTRFS_I(inode)->root;
         struct extent_buffer *leaf;
         int found_type;
@@ -169,6 +190,9 @@ again:
                        btrfs_file_extent_num_bytes(leaf, item);
                 err = 0;
 
+                if (loops && start != extent_start)
+                        goto not_found;
+
                 if (start < extent_start || start >= extent_end)
                         goto not_found;
 
@@ -191,6 +215,7 @@ loop:
                 return 0;
         }
         btrfs_release_path(root, path);
+        loops++;
         goto again;
 
 not_found:
@@ -202,6 +227,7 @@ not_found:
 static int run_delalloc_range(struct inode *inode, u64 start, u64 end)
 {
         struct btrfs_root *root = BTRFS_I(inode)->root;
+        u64 num_bytes;
         int ret;
 
         mutex_lock(&root->fs_info->fs_mutex);
@@ -209,6 +235,17 @@ static int run_delalloc_range(struct inode *inode, u64 start, u64 end)
                 ret = run_delalloc_nocow(inode, start, end);
         else
                 ret = cow_file_range(inode, start, end);
+
+        spin_lock(&root->fs_info->delalloc_lock);
+        num_bytes = end + 1 - start;
+        if (root->fs_info->delalloc_bytes < num_bytes) {
+                printk("delalloc accounting error total %llu sub %llu\n",
+                       root->fs_info->delalloc_bytes, num_bytes);
+        } else {
+                root->fs_info->delalloc_bytes -= num_bytes;
+        }
+        spin_unlock(&root->fs_info->delalloc_lock);
+
         mutex_unlock(&root->fs_info->fs_mutex);
         return ret;
 }
@@ -547,10 +584,15 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
         struct btrfs_root *root;
         struct btrfs_trans_handle *trans;
         int ret;
-        unsigned long nr;
+        unsigned long nr = 0;
 
         root = BTRFS_I(dir)->root;
         mutex_lock(&root->fs_info->fs_mutex);
+
+        ret = btrfs_check_free_space(root, 1, 1);
+        if (ret)
+                goto fail;
+
         trans = btrfs_start_transaction(root, 1);
 
         btrfs_set_trans_block_group(trans, dir);
@@ -558,25 +600,29 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
         nr = trans->blocks_used;
 
         btrfs_end_transaction(trans, root);
+fail:
         mutex_unlock(&root->fs_info->fs_mutex);
         btrfs_btree_balance_dirty(root, nr);
-
         return ret;
 }
 
 static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 {
         struct inode *inode = dentry->d_inode;
-        int err;
+        int err = 0;
         int ret;
         struct btrfs_root *root = BTRFS_I(dir)->root;
         struct btrfs_trans_handle *trans;
-        unsigned long nr;
+        unsigned long nr = 0;
 
         if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
                 return -ENOTEMPTY;
 
         mutex_lock(&root->fs_info->fs_mutex);
+        ret = btrfs_check_free_space(root, 1, 1);
+        if (ret)
+                goto fail;
+
         trans = btrfs_start_transaction(root, 1);
         btrfs_set_trans_block_group(trans, dir);
 
@@ -588,6 +634,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 
         nr = trans->blocks_used;
         ret = btrfs_end_transaction(trans, root);
+fail:
         mutex_unlock(&root->fs_info->fs_mutex);
         btrfs_btree_balance_dirty(root, nr);
 
@@ -792,17 +839,29 @@ static int btrfs_cow_one_page(struct inode *inode, struct page *page,
                               size_t zero_start)
 {
         char *kaddr;
-        int ret = 0;
         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
         u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
         u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
+        u64 existing_delalloc;
+        u64 delalloc_start;
+        int ret = 0;
 
         WARN_ON(!PageLocked(page));
         set_page_extent_mapped(page);
 
         lock_extent(em_tree, page_start, page_end, GFP_NOFS);
+        delalloc_start = page_start;
+        existing_delalloc = count_range_bits(&BTRFS_I(inode)->extent_tree,
+                                             &delalloc_start, page_end,
+                                             PAGE_CACHE_SIZE, EXTENT_DELALLOC);
         set_extent_delalloc(&BTRFS_I(inode)->extent_tree, page_start,
                             page_end, GFP_NOFS);
+
+        spin_lock(&root->fs_info->delalloc_lock);
+        root->fs_info->delalloc_bytes += PAGE_CACHE_SIZE - existing_delalloc;
+        spin_unlock(&root->fs_info->delalloc_lock);
+
         if (zero_start != PAGE_CACHE_SIZE) {
                 kaddr = kmap(page);
                 memset(kaddr + zero_start, 0, PAGE_CACHE_SIZE - zero_start);
@@ -881,6 +940,12 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
                 if (attr->ia_size <= pos)
                         goto out;
 
+                mutex_lock(&root->fs_info->fs_mutex);
+                err = btrfs_check_free_space(root, 1, 0);
+                mutex_unlock(&root->fs_info->fs_mutex);
+                if (err)
+                        goto fail;
+
                 btrfs_truncate_page(inode->i_mapping, inode->i_size);
 
                 lock_extent(em_tree, pos, block_end, GFP_NOFS);
@@ -906,7 +971,7 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
         }
 out:
         err = inode_setattr(inode, attr);
-
+fail:
         return err;
 }
 void btrfs_delete_inode(struct inode *inode)
@@ -1440,16 +1505,20 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
 {
         struct btrfs_trans_handle *trans;
         struct btrfs_root *root = BTRFS_I(dir)->root;
-        struct inode *inode;
+        struct inode *inode = NULL;
         int err;
         int drop_inode = 0;
         u64 objectid;
-        unsigned long nr;
+        unsigned long nr = 0;
 
         if (!new_valid_dev(rdev))
                 return -EINVAL;
 
         mutex_lock(&root->fs_info->fs_mutex);
+        err = btrfs_check_free_space(root, 1, 0);
+        if (err)
+                goto fail;
+
         trans = btrfs_start_transaction(root, 1);
         btrfs_set_trans_block_group(trans, dir);
 
@@ -1480,6 +1549,7 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
 out_unlock:
         nr = trans->blocks_used;
         btrfs_end_transaction(trans, root);
+fail:
         mutex_unlock(&root->fs_info->fs_mutex);
 
         if (drop_inode) {
@@ -1495,13 +1565,16 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 {
         struct btrfs_trans_handle *trans;
         struct btrfs_root *root = BTRFS_I(dir)->root;
-        struct inode *inode;
+        struct inode *inode = NULL;
         int err;
         int drop_inode = 0;
-        unsigned long nr;
+        unsigned long nr = 0;
         u64 objectid;
 
         mutex_lock(&root->fs_info->fs_mutex);
+        err = btrfs_check_free_space(root, 1, 0);
+        if (err)
+                goto fail;
         trans = btrfs_start_transaction(root, 1);
         btrfs_set_trans_block_group(trans, dir);
 
@@ -1535,6 +1608,7 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 out_unlock:
         nr = trans->blocks_used;
         btrfs_end_transaction(trans, root);
+fail:
         mutex_unlock(&root->fs_info->fs_mutex);
 
         if (drop_inode) {
@@ -1551,7 +1625,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
         struct btrfs_trans_handle *trans;
         struct btrfs_root *root = BTRFS_I(dir)->root;
         struct inode *inode = old_dentry->d_inode;
-        unsigned long nr;
+        unsigned long nr = 0;
         int err;
         int drop_inode = 0;
 
@@ -1564,6 +1638,9 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
         inc_nlink(inode);
 #endif
         mutex_lock(&root->fs_info->fs_mutex);
+        err = btrfs_check_free_space(root, 1, 0);
+        if (err)
+                goto fail;
         trans = btrfs_start_transaction(root, 1);
 
         btrfs_set_trans_block_group(trans, dir);
@@ -1582,6 +1659,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 
         nr = trans->blocks_used;
         btrfs_end_transaction(trans, root);
+fail:
         mutex_unlock(&root->fs_info->fs_mutex);
 
         if (drop_inode) {
@@ -1603,6 +1681,10 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
         unsigned long nr = 1;
 
         mutex_lock(&root->fs_info->fs_mutex);
+        err = btrfs_check_free_space(root, 1, 0);
+        if (err)
+                goto out_unlock;
+
         trans = btrfs_start_transaction(root, 1);
         btrfs_set_trans_block_group(trans, dir);
 
@@ -1869,6 +1951,15 @@ static sector_t btrfs_bmap(struct address_space *mapping, sector_t iblock)
 static int btrfs_prepare_write(struct file *file, struct page *page,
                                unsigned from, unsigned to)
 {
+        struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
+        int err;
+
+        mutex_lock(&root->fs_info->fs_mutex);
+        err = btrfs_check_free_space(root, PAGE_CACHE_SIZE, 0);
+        mutex_lock(&root->fs_info->fs_mutex);
+        if (err)
+                return -ENOSPC;
+
         return extent_prepare_write(&BTRFS_I(page->mapping->host)->extent_tree,
                                     page->mapping->host, page, from, to,
                                     btrfs_get_extent);
@@ -1880,6 +1971,7 @@ int btrfs_readpage(struct file *file, struct page *page)
         tree = &BTRFS_I(page->mapping->host)->extent_tree;
         return extent_read_full_page(tree, page, btrfs_get_extent);
 }
+
 static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 {
         struct extent_map_tree *tree;
@@ -1954,11 +2046,20 @@ static void btrfs_invalidatepage(struct page *page, unsigned long offset)
 int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
 {
         struct inode *inode = fdentry(vma->vm_file)->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
         unsigned long end;
         loff_t size;
-        int ret = -EINVAL;
+        int ret;
         u64 page_start;
 
+        mutex_lock(&root->fs_info->fs_mutex);
+        ret = btrfs_check_free_space(root, PAGE_CACHE_SIZE, 0);
+        mutex_lock(&root->fs_info->fs_mutex);
+        if (ret)
+                goto out;
+
+        ret = -EINVAL;
+
         down_read(&BTRFS_I(inode)->root->snap_sem);
         lock_page(page);
         wait_on_page_writeback(page);
@@ -1982,6 +2083,7 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
 out_unlock:
         up_read(&BTRFS_I(inode)->root->snap_sem);
         unlock_page(page);
+out:
         return ret;
 }
 
@@ -2046,6 +2148,10 @@ static int create_subvol(struct btrfs_root *root, char *name, int namelen)
         unsigned long nr = 1;
 
         mutex_lock(&root->fs_info->fs_mutex);
+        ret = btrfs_check_free_space(root, 1, 0);
+        if (ret)
+                goto fail_commit;
+
         trans = btrfs_start_transaction(root, 1);
         BUG_ON(!trans);
 
@@ -2162,7 +2268,7 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
         int ret;
         int err;
         u64 objectid;
-        unsigned long nr;
+        unsigned long nr = 0;
 
         if (!root->ref_cows)
                 return -EINVAL;
@@ -2172,6 +2278,10 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
         thaw_bdev(root->fs_info->sb->s_bdev, root->fs_info->sb);
 
         mutex_lock(&root->fs_info->fs_mutex);
+        ret = btrfs_check_free_space(root, 1, 0);
+        if (ret)
+                goto fail_unlock;
+
         trans = btrfs_start_transaction(root, 1);
         BUG_ON(!trans);
 
@@ -2229,7 +2339,7 @@ fail:
 
         if (err && !ret)
                 ret = err;
-
+fail_unlock:
         mutex_unlock(&root->fs_info->fs_mutex);
         up_write(&root->snap_sem);
         btrfs_btree_balance_dirty(root, nr);
@@ -2255,6 +2365,7 @@ static unsigned long force_ra(struct address_space *mapping,
 
 int btrfs_defrag_file(struct file *file) {
         struct inode *inode = fdentry(file)->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
         struct page *page;
         unsigned long last_index;
@@ -2262,6 +2373,13 @@ int btrfs_defrag_file(struct file *file) {
         u64 page_start;
         u64 page_end;
         unsigned long i;
+        int ret;
+
+        mutex_lock(&root->fs_info->fs_mutex);
+        ret = btrfs_check_free_space(root, inode->i_size, 0);
+        mutex_unlock(&root->fs_info->fs_mutex);
+        if (ret)
+                return -ENOSPC;
 
         mutex_lock(&inode->i_mutex);
         last_index = inode->i_size >> PAGE_CACHE_SHIFT;
@@ -2522,6 +2640,10 @@ static int btrfs_rename(struct inode * old_dir, struct dentry *old_dentry,
         }
 
         mutex_lock(&root->fs_info->fs_mutex);
+        ret = btrfs_check_free_space(root, 1, 0);
+        if (ret)
+                goto out_unlock;
+
         trans = btrfs_start_transaction(root, 1);
 
         btrfs_set_trans_block_group(trans, new_dir);
@@ -2553,6 +2675,7 @@ static int btrfs_rename(struct inode * old_dir, struct dentry *old_dentry,
 out_fail:
         btrfs_free_path(path);
         btrfs_end_transaction(trans, root);
+out_unlock:
         mutex_unlock(&root->fs_info->fs_mutex);
         return ret;
 }
@@ -2564,7 +2687,7 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
         struct btrfs_root *root = BTRFS_I(dir)->root;
         struct btrfs_path *path;
         struct btrfs_key key;
-        struct inode *inode;
+        struct inode *inode = NULL;
         int err;
         int drop_inode = 0;
         u64 objectid;
@@ -2573,12 +2696,17 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
         unsigned long ptr;
         struct btrfs_file_extent_item *ei;
         struct extent_buffer *leaf;
-        unsigned long nr;
+        unsigned long nr = 0;
 
         name_len = strlen(symname) + 1;
         if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(root))
                 return -ENAMETOOLONG;
+
         mutex_lock(&root->fs_info->fs_mutex);
+        err = btrfs_check_free_space(root, 1, 0);
+        if (err)
+                goto out_fail;
+
         trans = btrfs_start_transaction(root, 1);
         btrfs_set_trans_block_group(trans, dir);
 
@@ -2645,6 +2773,7 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 out_unlock:
         nr = trans->blocks_used;
         btrfs_end_transaction(trans, root);
+out_fail:
         mutex_unlock(&root->fs_info->fs_mutex);
         if (drop_inode) {
                 inode_dec_link_count(inode);