Merge Btrfs into fs/btrfs

1 files changed, 790 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
new file mode 100644
index 000000000000..4c6e0c15754d
--- /dev/null
+++ b/fs/btrfs/ioctl.c
@@ -0,0 +1,790 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bio.h>
+#include <linux/buffer_head.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+#include <linux/mpage.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/statfs.h>
+#include <linux/compat.h>
+#include <linux/bit_spinlock.h>
+#include <linux/version.h>
+#include <linux/xattr.h>
+#include <linux/vmalloc.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "btrfs_inode.h"
+#include "ioctl.h"
+#include "print-tree.h"
+#include "volumes.h"
+#include "locking.h"
+
+
+
+static noinline int create_subvol(struct btrfs_root *root, char *name,
+                                  int namelen)
+{
+        struct btrfs_trans_handle *trans;
+        struct btrfs_key key;
+        struct btrfs_root_item root_item;
+        struct btrfs_inode_item *inode_item;
+        struct extent_buffer *leaf;
+        struct btrfs_root *new_root = root;
+        struct inode *dir;
+        int ret;
+        int err;
+        u64 objectid;
+        u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
+        unsigned long nr = 1;
+
+        ret = btrfs_check_free_space(root, 1, 0);
+        if (ret)
+                goto fail_commit;
+
+        trans = btrfs_start_transaction(root, 1);
+        BUG_ON(!trans);
+
+        ret = btrfs_find_free_objectid(trans, root->fs_info->tree_root,
+                                       0, &objectid);
+        if (ret)
+                goto fail;
+
+        leaf = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
+                                      objectid, trans->transid, 0, 0, 0);
+        if (IS_ERR(leaf)) {
+                ret = PTR_ERR(leaf);
+                goto fail;
+        }
+
+        btrfs_set_header_nritems(leaf, 0);
+        btrfs_set_header_level(leaf, 0);
+        btrfs_set_header_bytenr(leaf, leaf->start);
+        btrfs_set_header_generation(leaf, trans->transid);
+        btrfs_set_header_owner(leaf, objectid);
+
+        write_extent_buffer(leaf, root->fs_info->fsid,
+                            (unsigned long)btrfs_header_fsid(leaf),
+                            BTRFS_FSID_SIZE);
+        btrfs_mark_buffer_dirty(leaf);
+
+        inode_item = &root_item.inode;
+        memset(inode_item, 0, sizeof(*inode_item));
+        inode_item->generation = cpu_to_le64(1);
+        inode_item->size = cpu_to_le64(3);
+        inode_item->nlink = cpu_to_le32(1);
+        inode_item->nblocks = cpu_to_le64(1);
+        inode_item->mode = cpu_to_le32(S_IFDIR | 0755);
+
+        btrfs_set_root_bytenr(&root_item, leaf->start);
+        btrfs_set_root_level(&root_item, 0);
+        btrfs_set_root_refs(&root_item, 1);
+        btrfs_set_root_used(&root_item, 0);
+
+        memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
+        root_item.drop_level = 0;
+
+        btrfs_tree_unlock(leaf);
+        free_extent_buffer(leaf);
+        leaf = NULL;
+
+        btrfs_set_root_dirid(&root_item, new_dirid);
+
+        key.objectid = objectid;
+        key.offset = 1;
+        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+        ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
+                                &root_item);
+        if (ret)
+                goto fail;
+
+        /*
+         * insert the directory item
+         */
+        key.offset = (u64)-1;
+        dir = root->fs_info->sb->s_root->d_inode;
+        ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
+                                    name, namelen, dir->i_ino, &key,
+                                    BTRFS_FT_DIR, 0);
+        if (ret)
+                goto fail;
+
+        ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
+                             name, namelen, objectid,
+                             root->fs_info->sb->s_root->d_inode->i_ino, 0);
+        if (ret)
+                goto fail;
+
+        ret = btrfs_commit_transaction(trans, root);
+        if (ret)
+                goto fail_commit;
+
+        new_root = btrfs_read_fs_root(root->fs_info, &key, name, namelen);
+        BUG_ON(!new_root);
+
+        trans = btrfs_start_transaction(new_root, 1);
+        BUG_ON(!trans);
+
+        ret = btrfs_create_subvol_root(new_root, trans, new_dirid,
+                                       BTRFS_I(dir)->block_group);
+        if (ret)
+                goto fail;
+
+        /* Invalidate existing dcache entry for new subvolume. */
+        btrfs_invalidate_dcache_root(root, name, namelen);
+
+fail:
+        nr = trans->blocks_used;
+        err = btrfs_commit_transaction(trans, new_root);
+        if (err && !ret)
+                ret = err;
+fail_commit:
+        btrfs_btree_balance_dirty(root, nr);
+        return ret;
+}
+
+static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
+{
+        struct btrfs_pending_snapshot *pending_snapshot;
+        struct btrfs_trans_handle *trans;
+        int ret;
+        int err;
+        unsigned long nr = 0;
+
+        if (!root->ref_cows)
+                return -EINVAL;
+
+        ret = btrfs_check_free_space(root, 1, 0);
+        if (ret)
+                goto fail_unlock;
+
+        pending_snapshot = kmalloc(sizeof(*pending_snapshot), GFP_NOFS);
+        if (!pending_snapshot) {
+                ret = -ENOMEM;
+                goto fail_unlock;
+        }
+        pending_snapshot->name = kmalloc(namelen + 1, GFP_NOFS);
+        if (!pending_snapshot->name) {
+                ret = -ENOMEM;
+                kfree(pending_snapshot);
+                goto fail_unlock;
+        }
+        memcpy(pending_snapshot->name, name, namelen);
+        pending_snapshot->name[namelen] = '\0';
+        trans = btrfs_start_transaction(root, 1);
+        BUG_ON(!trans);
+        pending_snapshot->root = root;
+        list_add(&pending_snapshot->list,
+                 &trans->transaction->pending_snapshots);
+        ret = btrfs_update_inode(trans, root, root->inode);
+        err = btrfs_commit_transaction(trans, root);
+
+fail_unlock:
+        btrfs_btree_balance_dirty(root, nr);
+        return ret;
+}
+
+int btrfs_defrag_file(struct file *file)
+{
+        struct inode *inode = fdentry(file)->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+        struct btrfs_ordered_extent *ordered;
+        struct page *page;
+        unsigned long last_index;
+        unsigned long ra_pages = root->fs_info->bdi.ra_pages;
+        unsigned long total_read = 0;
+        u64 page_start;
+        u64 page_end;
+        unsigned long i;
+        int ret;
+
+        ret = btrfs_check_free_space(root, inode->i_size, 0);
+        if (ret)
+                return -ENOSPC;
+
+        mutex_lock(&inode->i_mutex);
+        last_index = inode->i_size >> PAGE_CACHE_SHIFT;
+        for (i = 0; i <= last_index; i++) {
+                if (total_read % ra_pages == 0) {
+                        btrfs_force_ra(inode->i_mapping, &file->f_ra, file, i,
+                                       min(last_index, i + ra_pages - 1));
+                }
+                total_read++;
+again:
+                page = grab_cache_page(inode->i_mapping, i);
+                if (!page)
+                        goto out_unlock;
+                if (!PageUptodate(page)) {
+                        btrfs_readpage(NULL, page);
+                        lock_page(page);
+                        if (!PageUptodate(page)) {
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto out_unlock;
+                        }
+                }
+
+                wait_on_page_writeback(page);
+
+                page_start = (u64)page->index << PAGE_CACHE_SHIFT;
+                page_end = page_start + PAGE_CACHE_SIZE - 1;
+                lock_extent(io_tree, page_start, page_end, GFP_NOFS);
+
+                ordered = btrfs_lookup_ordered_extent(inode, page_start);
+                if (ordered) {
+                        unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
+                        unlock_page(page);
+                        page_cache_release(page);
+                        btrfs_start_ordered_extent(inode, ordered, 1);
+                        btrfs_put_ordered_extent(ordered);
+                        goto again;
+                }
+                set_page_extent_mapped(page);
+
+                /*
+                 * this makes sure page_mkwrite is called on the
+                 * page if it is dirtied again later
+                 */
+                clear_page_dirty_for_io(page);
+
+                btrfs_set_extent_delalloc(inode, page_start, page_end);
+
+                unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
+                set_page_dirty(page);
+                unlock_page(page);
+                page_cache_release(page);
+                balance_dirty_pages_ratelimited_nr(inode->i_mapping, 1);
+        }
+
+out_unlock:
+        mutex_unlock(&inode->i_mutex);
+        return 0;
+}
+
+/*
+ * Called inside transaction, so use GFP_NOFS
+ */
+
+static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
+{
+        u64 new_size;
+        u64 old_size;
+        u64 devid = 1;
+        struct btrfs_ioctl_vol_args *vol_args;
+        struct btrfs_trans_handle *trans;
+        struct btrfs_device *device = NULL;
+        char *sizestr;
+        char *devstr = NULL;
+        int ret = 0;
+        int namelen;
+        int mod = 0;
+
+        vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
+
+        if (!vol_args)
+                return -ENOMEM;
+
+        if (copy_from_user(vol_args, arg, sizeof(*vol_args))) {
+                ret = -EFAULT;
+                goto out;
+        }
+
+        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+        namelen = strlen(vol_args->name);
+
+        mutex_lock(&root->fs_info->volume_mutex);
+        sizestr = vol_args->name;
+        devstr = strchr(sizestr, ':');
+        if (devstr) {
+                char *end;
+                sizestr = devstr + 1;
+                *devstr = '\0';
+                devstr = vol_args->name;
+                devid = simple_strtoull(devstr, &end, 10);
+                printk(KERN_INFO "resizing devid %llu\n", devid);
+        }
+        device = btrfs_find_device(root, devid, NULL);
+        if (!device) {
+                printk(KERN_INFO "resizer unable to find device %llu\n", devid);
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+        if (!strcmp(sizestr, "max"))
+                new_size = device->bdev->bd_inode->i_size;
+        else {
+                if (sizestr[0] == '-') {
+                        mod = -1;
+                        sizestr++;
+                } else if (sizestr[0] == '+') {
+                        mod = 1;
+                        sizestr++;
+                }
+                new_size = btrfs_parse_size(sizestr);
+                if (new_size == 0) {
+                        ret = -EINVAL;
+                        goto out_unlock;
+                }
+        }
+
+        old_size = device->total_bytes;
+
+        if (mod < 0) {
+                if (new_size > old_size) {
+                        ret = -EINVAL;
+                        goto out_unlock;
+                }
+                new_size = old_size - new_size;
+        } else if (mod > 0) {
+                new_size = old_size + new_size;
+        }
+
+        if (new_size < 256 * 1024 * 1024) {
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+        if (new_size > device->bdev->bd_inode->i_size) {
+                ret = -EFBIG;
+                goto out_unlock;
+        }
+
+        do_div(new_size, root->sectorsize);
+        new_size *= root->sectorsize;
+
+        printk(KERN_INFO "new size for %s is %llu\n",
+                device->name, (unsigned long long)new_size);
+
+        if (new_size > old_size) {
+                trans = btrfs_start_transaction(root, 1);
+                ret = btrfs_grow_device(trans, device, new_size);
+                btrfs_commit_transaction(trans, root);
+        } else {
+                ret = btrfs_shrink_device(device, new_size);
+        }
+
+out_unlock:
+        mutex_unlock(&root->fs_info->volume_mutex);
+out:
+        kfree(vol_args);
+        return ret;
+}
+
+static noinline int btrfs_ioctl_snap_create(struct btrfs_root *root,
+                                            void __user *arg)
+{
+        struct btrfs_ioctl_vol_args *vol_args;
+        struct btrfs_dir_item *di;
+        struct btrfs_path *path;
+        u64 root_dirid;
+        int namelen;
+        int ret;
+
+        vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
+
+        if (!vol_args)
+                return -ENOMEM;
+
+        if (copy_from_user(vol_args, arg, sizeof(*vol_args))) {
+                ret = -EFAULT;
+                goto out;
+        }
+
+        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+        namelen = strlen(vol_args->name);
+        if (strchr(vol_args->name, '/')) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        path = btrfs_alloc_path();
+        if (!path) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        root_dirid = root->fs_info->sb->s_root->d_inode->i_ino,
+        di = btrfs_lookup_dir_item(NULL, root->fs_info->tree_root,
+                            path, root_dirid,
+                            vol_args->name, namelen, 0);
+        btrfs_free_path(path);
+
+        if (di && !IS_ERR(di)) {
+                ret = -EEXIST;
+                goto out;
+        }
+
+        if (IS_ERR(di)) {
+                ret = PTR_ERR(di);
+                goto out;
+        }
+
+        mutex_lock(&root->fs_info->drop_mutex);
+        if (root == root->fs_info->tree_root)
+                ret = create_subvol(root, vol_args->name, namelen);
+        else
+                ret = create_snapshot(root, vol_args->name, namelen);
+        mutex_unlock(&root->fs_info->drop_mutex);
+out:
+        kfree(vol_args);
+        return ret;
+}
+
+static int btrfs_ioctl_defrag(struct file *file)
+{
+        struct inode *inode = fdentry(file)->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+
+        switch (inode->i_mode & S_IFMT) {
+        case S_IFDIR:
+                btrfs_defrag_root(root, 0);
+                btrfs_defrag_root(root->fs_info->extent_root, 0);
+                break;
+        case S_IFREG:
+                btrfs_defrag_file(file);
+                break;
+        }
+
+        return 0;
+}
+
+long btrfs_ioctl_add_dev(struct btrfs_root *root, void __user *arg)
+{
+        struct btrfs_ioctl_vol_args *vol_args;
+        int ret;
+
+        vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
+
+        if (!vol_args)
+                return -ENOMEM;
+
+        if (copy_from_user(vol_args, arg, sizeof(*vol_args))) {
+                ret = -EFAULT;
+                goto out;
+        }
+        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+        ret = btrfs_init_new_device(root, vol_args->name);
+
+out:
+        kfree(vol_args);
+        return ret;
+}
+
+long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
+{
+        struct btrfs_ioctl_vol_args *vol_args;
+        int ret;
+
+        vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
+
+        if (!vol_args)
+                return -ENOMEM;
+
+        if (copy_from_user(vol_args, arg, sizeof(*vol_args))) {
+                ret = -EFAULT;
+                goto out;
+        }
+        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+        ret = btrfs_rm_device(root, vol_args->name);
+
+out:
+        kfree(vol_args);
+        return ret;
+}
+
+long btrfs_ioctl_clone(struct file *file, unsigned long src_fd)
+{
+        struct inode *inode = fdentry(file)->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct file *src_file;
+        struct inode *src;
+        struct btrfs_trans_handle *trans;
+        struct btrfs_path *path;
+        struct extent_buffer *leaf;
+        char *buf;
+        struct btrfs_key key;
+        u32 nritems;
+        int slot;
+        int ret;
+
+        src_file = fget(src_fd);
+        if (!src_file)
+                return -EBADF;
+        src = src_file->f_dentry->d_inode;
+
+        ret = -EISDIR;
+        if (S_ISDIR(src->i_mode) || S_ISDIR(inode->i_mode))
+                goto out_fput;
+
+        ret = -EXDEV;
+        if (src->i_sb != inode->i_sb || BTRFS_I(src)->root != root)
+                goto out_fput;
+
+        ret = -ENOMEM;
+        buf = vmalloc(btrfs_level_size(root, 0));
+        if (!buf)
+                goto out_fput;
+
+        path = btrfs_alloc_path();
+        if (!path) {
+                vfree(buf);
+                goto out_fput;
+        }
+        path->reada = 2;
+
+        if (inode < src) {
+                mutex_lock(&inode->i_mutex);
+                mutex_lock(&src->i_mutex);
+        } else {
+                mutex_lock(&src->i_mutex);
+                mutex_lock(&inode->i_mutex);
+        }
+
+        ret = -ENOTEMPTY;
+        if (inode->i_size)
+                goto out_unlock;
+
+        /* do any pending delalloc/csum calc on src, one way or
+           another, and lock file content */
+        while (1) {
+                struct btrfs_ordered_extent *ordered;
+                lock_extent(&BTRFS_I(src)->io_tree, 0, (u64)-1, GFP_NOFS);
+                ordered = btrfs_lookup_first_ordered_extent(inode, (u64)-1);
+                if (BTRFS_I(src)->delalloc_bytes == 0 && !ordered)
+                        break;
+                unlock_extent(&BTRFS_I(src)->io_tree, 0, (u64)-1, GFP_NOFS);
+                if (ordered)
+                        btrfs_put_ordered_extent(ordered);
+                btrfs_wait_ordered_range(src, 0, (u64)-1);
+        }
+
+        trans = btrfs_start_transaction(root, 1);
+        BUG_ON(!trans);
+
+        key.objectid = src->i_ino;
+        key.type = BTRFS_EXTENT_DATA_KEY;
+        key.offset = 0;
+
+        while (1) {
+                /*
+                 * note the key will change type as we walk through the
+                 * tree.
+                 */
+                ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
+                if (ret < 0)
+                        goto out;
+
+                nritems = btrfs_header_nritems(path->nodes[0]);
+                if (path->slots[0] >= nritems) {
+                        ret = btrfs_next_leaf(root, path);
+                        if (ret < 0)
+                                goto out;
+                        if (ret > 0)
+                                break;
+                        nritems = btrfs_header_nritems(path->nodes[0]);
+                }
+                leaf = path->nodes[0];
+                slot = path->slots[0];
+
+                btrfs_item_key_to_cpu(leaf, &key, slot);
+                if (btrfs_key_type(&key) > BTRFS_CSUM_ITEM_KEY ||
+                    key.objectid != src->i_ino)
+                        break;
+
+                if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY ||
+                    btrfs_key_type(&key) == BTRFS_CSUM_ITEM_KEY) {
+                        u32 size;
+                        struct btrfs_key new_key;
+
+                        size = btrfs_item_size_nr(leaf, slot);
+                        read_extent_buffer(leaf, buf,
+                                           btrfs_item_ptr_offset(leaf, slot),
+                                           size);
+                        btrfs_release_path(root, path);
+
+                        memcpy(&new_key, &key, sizeof(new_key));
+                        new_key.objectid = inode->i_ino;
+                        ret = btrfs_insert_empty_item(trans, root, path,
+                                                      &new_key, size);
+                        if (ret)
+                                goto out;
+
+                        leaf = path->nodes[0];
+                        slot = path->slots[0];
+                        write_extent_buffer(leaf, buf,
+                                            btrfs_item_ptr_offset(leaf, slot),
+                                            size);
+                        btrfs_mark_buffer_dirty(leaf);
+                }
+
+                if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
+                        struct btrfs_file_extent_item *extent;
+                        int found_type;
+
+                        extent = btrfs_item_ptr(leaf, slot,
+                                                struct btrfs_file_extent_item);
+                        found_type = btrfs_file_extent_type(leaf, extent);
+                        if (found_type == BTRFS_FILE_EXTENT_REG) {
+                                u64 ds = btrfs_file_extent_disk_bytenr(leaf,
+                                                                       extent);
+                                u64 dl = btrfs_file_extent_disk_num_bytes(leaf,
+                                                                 extent);
+                                /* ds == 0 means there's a hole */
+                                if (ds != 0) {
+                                        ret = btrfs_inc_extent_ref(trans, root,
+                                                     ds, dl, leaf->start,
+                                                     root->root_key.objectid,
+                                                     trans->transid,
+                                                     inode->i_ino, key.offset);
+                                        BUG_ON(ret);
+                                }
+                        }
+                }
+                btrfs_release_path(root, path);
+                key.offset++;
+        }
+        ret = 0;
+out:
+        btrfs_release_path(root, path);
+        if (ret == 0) {
+                inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+                inode->i_blocks = src->i_blocks;
+                btrfs_i_size_write(inode, src->i_size);
+                BTRFS_I(inode)->flags = BTRFS_I(src)->flags;
+                ret = btrfs_update_inode(trans, root, inode);
+        }
+        btrfs_end_transaction(trans, root);
+        unlock_extent(&BTRFS_I(src)->io_tree, 0, (u64)-1, GFP_NOFS);
+        if (ret)
+                vmtruncate(inode, 0);
+out_unlock:
+        mutex_unlock(&src->i_mutex);
+        mutex_unlock(&inode->i_mutex);
+        vfree(buf);
+        btrfs_free_path(path);
+out_fput:
+        fput(src_file);
+        return ret;
+}
+
+/*
+ * there are many ways the trans_start and trans_end ioctls can lead
+ * to deadlocks.  They should only be used by applications that
+ * basically own the machine, and have a very in depth understanding
+ * of all the possible deadlocks and enospc problems.
+ */
+long btrfs_ioctl_trans_start(struct file *file)
+{
+        struct inode *inode = fdentry(file)->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct btrfs_trans_handle *trans;
+        int ret = 0;
+
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        if (file->private_data) {
+                ret = -EINPROGRESS;
+                goto out;
+        }
+
+        mutex_lock(&root->fs_info->trans_mutex);
+        root->fs_info->open_ioctl_trans++;
+        mutex_unlock(&root->fs_info->trans_mutex);
+
+        trans = btrfs_start_ioctl_transaction(root, 0);
+        if (trans)
+                file->private_data = trans;
+        else
+                ret = -ENOMEM;
+        /*printk(KERN_INFO "btrfs_ioctl_trans_start on %p\n", file);*/
+out:
+        return ret;
+}
+
+/*
+ * there are many ways the trans_start and trans_end ioctls can lead
+ * to deadlocks.  They should only be used by applications that
+ * basically own the machine, and have a very in depth understanding
+ * of all the possible deadlocks and enospc problems.
+ */
+long btrfs_ioctl_trans_end(struct file *file)
+{
+        struct inode *inode = fdentry(file)->d_inode;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct btrfs_trans_handle *trans;
+        int ret = 0;
+
+        trans = file->private_data;
+        if (!trans) {
+                ret = -EINVAL;
+                goto out;
+        }
+        btrfs_end_transaction(trans, root);
+        file->private_data = NULL;
+
+        mutex_lock(&root->fs_info->trans_mutex);
+        root->fs_info->open_ioctl_trans--;
+        mutex_unlock(&root->fs_info->trans_mutex);
+
+out:
+        return ret;
+}
+
+long btrfs_ioctl(struct file *file, unsigned int
+                cmd, unsigned long arg)
+{
+        struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+
+        switch (cmd) {
+        case BTRFS_IOC_SNAP_CREATE:
+                return btrfs_ioctl_snap_create(root, (void __user *)arg);
+        case BTRFS_IOC_DEFRAG:
+                return btrfs_ioctl_defrag(file);
+        case BTRFS_IOC_RESIZE:
+                return btrfs_ioctl_resize(root, (void __user *)arg);
+        case BTRFS_IOC_ADD_DEV:
+                return btrfs_ioctl_add_dev(root, (void __user *)arg);
+        case BTRFS_IOC_RM_DEV:
+                return btrfs_ioctl_rm_dev(root, (void __user *)arg);
+        case BTRFS_IOC_BALANCE:
+                return btrfs_balance(root->fs_info->dev_root);
+        case BTRFS_IOC_CLONE:
+                return btrfs_ioctl_clone(file, arg);
+        case BTRFS_IOC_TRANS_START:
+                return btrfs_ioctl_trans_start(file);
+        case BTRFS_IOC_TRANS_END:
+                return btrfs_ioctl_trans_end(file);
+        case BTRFS_IOC_SYNC:
+                btrfs_start_delalloc_inodes(root);
+                btrfs_sync_fs(file->f_dentry->d_sb, 1);
+                return 0;
+        }
+
+        return -ENOTTY;
+}