Btrfs: corruptions fixed

[mirror_ubuntu-artful-kernel.git] / fs / btrfs / super.c

#include <linux/module.h>
#include <linux/buffer_head.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 "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "btrfs_inode.h"

#define BTRFS_SUPER_MAGIC 0x9123682E

static struct inode_operations btrfs_dir_inode_operations;
static struct super_operations btrfs_super_ops;
static struct file_operations btrfs_dir_file_operations;
static struct inode_operations btrfs_file_inode_operations;
static struct address_space_operations btrfs_aops;
static struct file_operations btrfs_file_operations;

static int check_inode(struct inode *inode)
{
        struct btrfs_inode *ei = BTRFS_I(inode);
        WARN_ON(ei->magic != 0xDEADBEEF);
        WARN_ON(ei->magic2 != 0xDEADBEAF);
        return 0;
}

static void btrfs_read_locked_inode(struct inode *inode)
{
        struct btrfs_path *path;
        struct btrfs_inode_item *inode_item;
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        int ret;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
        mutex_lock(&root->fs_info->fs_mutex);

        check_inode(inode);
        ret = btrfs_lookup_inode(NULL, root, path, inode->i_ino, 0);
        if (ret) {
                btrfs_release_path(root, path);
                btrfs_free_path(path);
                mutex_unlock(&root->fs_info->fs_mutex);
                make_bad_inode(inode);
                return;
        }
        check_inode(inode);
        inode_item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
                                  path->slots[0],
                                  struct btrfs_inode_item);

        inode->i_mode = btrfs_inode_mode(inode_item);
        inode->i_nlink = btrfs_inode_nlink(inode_item);
        inode->i_uid = btrfs_inode_uid(inode_item);
        inode->i_gid = btrfs_inode_gid(inode_item);
        inode->i_size = btrfs_inode_size(inode_item);
        inode->i_atime.tv_sec = btrfs_timespec_sec(&inode_item->atime);
        inode->i_atime.tv_nsec = btrfs_timespec_nsec(&inode_item->atime);
        inode->i_mtime.tv_sec = btrfs_timespec_sec(&inode_item->mtime);
        inode->i_mtime.tv_nsec = btrfs_timespec_nsec(&inode_item->mtime);
        inode->i_ctime.tv_sec = btrfs_timespec_sec(&inode_item->ctime);
        inode->i_ctime.tv_nsec = btrfs_timespec_nsec(&inode_item->ctime);
        inode->i_blocks = btrfs_inode_nblocks(inode_item);
        inode->i_generation = btrfs_inode_generation(inode_item);

        btrfs_release_path(root, path);
        btrfs_free_path(path);
        inode_item = NULL;

        mutex_unlock(&root->fs_info->fs_mutex);
        check_inode(inode);
        switch (inode->i_mode & S_IFMT) {
#if 0
        default:
                init_special_inode(inode, inode->i_mode,
                                   btrfs_inode_rdev(inode_item));
                break;
#endif
        case S_IFREG:
                inode->i_mapping->a_ops = &btrfs_aops;
                inode->i_fop = &btrfs_file_operations;
                inode->i_op = &btrfs_file_inode_operations;
                break;
        case S_IFDIR:
                inode->i_op = &btrfs_dir_inode_operations;
                inode->i_fop = &btrfs_dir_file_operations;
                break;
        case S_IFLNK:
                // inode->i_op = &page_symlink_inode_operations;
                break;
        }
        check_inode(inode);
        return;
}

static int btrfs_unlink_trans(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root,
                              struct inode *dir,
                              struct dentry *dentry)
{
        struct btrfs_path *path;
        const char *name = dentry->d_name.name;
        int name_len = dentry->d_name.len;
        int ret;
        u64 objectid;
        struct btrfs_dir_item *di;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
        ret = btrfs_lookup_dir_item(trans, root, path, dir->i_ino,
                                    name, name_len, -1);
        if (ret < 0)
                goto err;
        if (ret > 0) {
                ret = -ENOENT;
                goto err;
        }
        di = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                            struct btrfs_dir_item);
        objectid = btrfs_dir_objectid(di);

        ret = btrfs_del_item(trans, root, path);
        BUG_ON(ret);
        dentry->d_inode->i_ctime = dir->i_ctime;
err:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        if (ret == 0)
                inode_dec_link_count(dentry->d_inode);
        return ret;
}

static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
{
        struct btrfs_root *root;
        struct btrfs_trans_handle *trans;
        int ret;

        root = btrfs_sb(dir->i_sb);
        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        ret = btrfs_unlink_trans(trans, root, dir, dentry);
        btrfs_end_transaction(trans, root);
        mutex_unlock(&root->fs_info->fs_mutex);
        return ret;
}

static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct inode *inode = dentry->d_inode;
        int err;
        int ret;
        struct btrfs_root *root = btrfs_sb(dir->i_sb);
        struct btrfs_path *path;
        struct btrfs_key key;
        struct btrfs_trans_handle *trans;
        struct btrfs_disk_key *found_key;
        struct btrfs_leaf *leaf;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        key.objectid = inode->i_ino;
        key.offset = (u64)-1;
        key.flags = 0;
        btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
        if (ret < 0) {
                err = ret;
                goto out;
        }

        BUG_ON(ret == 0);
        BUG_ON(path->slots[0] == 0);
        path->slots[0]--;
        leaf = btrfs_buffer_leaf(path->nodes[0]);
        found_key = &leaf->items[path->slots[0]].key;
        if (btrfs_disk_key_objectid(found_key) != inode->i_ino) {
                err = -ENOENT;
                goto out;
        }
        if (btrfs_disk_key_type(found_key) != BTRFS_DIR_ITEM_KEY ||
            btrfs_disk_key_offset(found_key) != 2) {
                err = -ENOTEMPTY;
                goto out;
        }
        ret = btrfs_del_item(trans, root, path);
        BUG_ON(ret);
        btrfs_release_path(root, path);
        key.offset = 1;
        ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
        if (ret < 0) {
                err = ret;
                goto out;
        }
        if (ret > 0) {
                err = -ENOTEMPTY;
                goto out;
        }
        ret = btrfs_del_item(trans, root, path);
        if (ret) {
                err = ret;
                goto out;
        }
        btrfs_release_path(root, path);

        /* now the directory is empty */
        err = btrfs_unlink_trans(trans, root, dir, dentry);
        if (!err) {
                inode->i_size = 0;
        }
out:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        mutex_unlock(&root->fs_info->fs_mutex);
        ret = btrfs_end_transaction(trans, root);
        if (ret && !err)
                err = ret;
        return err;
}

static int btrfs_free_inode(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root,
                            struct inode *inode)
{
        u64 objectid = inode->i_ino;
        struct btrfs_path *path;
        struct btrfs_inode_map_item *map;
        struct btrfs_key stat_data_key;
        int ret;

        clear_inode(inode);

        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
        ret = btrfs_lookup_inode_map(trans, root, path, objectid, -1);
        if (ret) {
                if (ret > 0)
                        ret = -ENOENT;
                goto error;
        }
        map = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                            struct btrfs_inode_map_item);
        btrfs_disk_key_to_cpu(&stat_data_key, &map->key);
        ret = btrfs_del_item(trans, root->fs_info->inode_root, path);
        BUG_ON(ret);
        btrfs_release_path(root, path);

        ret = btrfs_lookup_inode(trans, root, path, objectid, -1);
        BUG_ON(ret);
        ret = btrfs_del_item(trans, root, path);
        BUG_ON(ret);
error:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        return ret;
}

static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
                                   struct btrfs_root *root,
                                   struct inode *inode)
{
        int ret;
        struct btrfs_path *path;
        struct btrfs_key key;
        struct btrfs_disk_key *found_key;
        struct btrfs_leaf *leaf;
        struct btrfs_file_extent_item *fi = NULL;
        u64 extent_start = 0;
        u64 extent_num_blocks = 0;
        int found_extent;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        /* FIXME, add redo link to tree so we don't leak on crash */
        key.objectid = inode->i_ino;
        key.offset = (u64)-1;
        key.flags = 0;
        btrfs_set_key_type(&key, BTRFS_CSUM_ITEM_KEY);
        while(1) {
                btrfs_init_path(path);
                ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
                if (ret < 0) {
                        goto error;
                }
                if (ret > 0) {
                        BUG_ON(path->slots[0] == 0);
                        path->slots[0]--;
                }
                leaf = btrfs_buffer_leaf(path->nodes[0]);
                found_key = &leaf->items[path->slots[0]].key;
                if (btrfs_disk_key_objectid(found_key) != inode->i_ino)
                        break;
                if (btrfs_disk_key_type(found_key) != BTRFS_CSUM_ITEM_KEY &&
                    btrfs_disk_key_type(found_key) != BTRFS_EXTENT_DATA_KEY)
                        break;
                if (btrfs_disk_key_offset(found_key) < inode->i_size)
                        break;
                if (btrfs_disk_key_type(found_key) == BTRFS_EXTENT_DATA_KEY) {
                        fi = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
                                            path->slots[0],
                                            struct btrfs_file_extent_item);
                        extent_start = btrfs_file_extent_disk_blocknr(fi);
                        extent_num_blocks =
                                btrfs_file_extent_disk_num_blocks(fi);
                        inode->i_blocks -=
                                btrfs_file_extent_num_blocks(fi) >> 9;
                        found_extent = 1;
                } else {
                        found_extent = 0;
                }
                ret = btrfs_del_item(trans, root, path);
                BUG_ON(ret);
                btrfs_release_path(root, path);
                if (found_extent) {
                        ret = btrfs_free_extent(trans, root, extent_start,
                                                extent_num_blocks, 0);
                        BUG_ON(ret);
                }
        }
        ret = 0;
error:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        return ret;
}

static void btrfs_delete_inode(struct inode *inode)
{
        struct btrfs_trans_handle *trans;
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        int ret;

        truncate_inode_pages(&inode->i_data, 0);
        if (is_bad_inode(inode)) {
                goto no_delete;
        }
        inode->i_size = 0;
        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        if (S_ISREG(inode->i_mode)) {
                ret = btrfs_truncate_in_trans(trans, root, inode);
                BUG_ON(ret);
        }
        btrfs_free_inode(trans, root, inode);
        btrfs_end_transaction(trans, root);
        mutex_unlock(&root->fs_info->fs_mutex);
        return;
no_delete:
        clear_inode(inode);
}

static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
                              ino_t *ino)
{
        const char *name = dentry->d_name.name;
        int namelen = dentry->d_name.len;
        struct btrfs_dir_item *di;
        struct btrfs_path *path;
        struct btrfs_root *root = btrfs_sb(dir->i_sb);
        int ret;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
        ret = btrfs_lookup_dir_item(NULL, root, path, dir->i_ino, name,
                                    namelen, 0);
        if (ret || !btrfs_match_dir_item_name(root, path, name, namelen)) {
                *ino = 0;
                ret = 0;
                goto out;
        }
        di = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                            struct btrfs_dir_item);
        *ino = btrfs_dir_objectid(di);
out:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        check_inode(dir);
        return ret;
}

static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
                                   struct nameidata *nd)
{
        struct inode * inode;
        struct btrfs_root *root = btrfs_sb(dir->i_sb);
        ino_t ino;
        int ret;

        if (dentry->d_name.len > BTRFS_NAME_LEN)
                return ERR_PTR(-ENAMETOOLONG);
        mutex_lock(&root->fs_info->fs_mutex);
        ret = btrfs_inode_by_name(dir, dentry, &ino);
        mutex_unlock(&root->fs_info->fs_mutex);
        if (ret < 0)
                return ERR_PTR(ret);
        inode = NULL;
        if (ino) {
                inode = iget(dir->i_sb, ino);
                if (!inode)
                        return ERR_PTR(-EACCES);
                check_inode(inode);
        }
        check_inode(dir);
        return d_splice_alias(inode, dentry);
}

static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
        struct inode *inode = filp->f_path.dentry->d_inode;
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        struct btrfs_item *item;
        struct btrfs_dir_item *di;
        struct btrfs_key key;
        struct btrfs_path *path;
        int ret;
        u32 nritems;
        struct btrfs_leaf *leaf;
        int slot;
        int advance;
        unsigned char d_type = DT_UNKNOWN;
        int over = 0;

        mutex_lock(&root->fs_info->fs_mutex);
        key.objectid = inode->i_ino;
        key.flags = 0;
        btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
        key.offset = filp->f_pos;
        path = btrfs_alloc_path();
        btrfs_init_path(path);
        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0) {
                goto err;
        }
        advance = 0;
        while(1) {
                leaf = btrfs_buffer_leaf(path->nodes[0]);
                nritems = btrfs_header_nritems(&leaf->header);
                slot = path->slots[0];
                if (advance || slot >= nritems) {
                        if (slot >= nritems -1) {
                                ret = btrfs_next_leaf(root, path);
                                if (ret)
                                        break;
                                leaf = btrfs_buffer_leaf(path->nodes[0]);
                                nritems = btrfs_header_nritems(&leaf->header);
                                slot = path->slots[0];
                        } else {
                                slot++;
                                path->slots[0]++;
                        }
                }
                advance = 1;
                item = leaf->items + slot;
                if (btrfs_disk_key_objectid(&item->key) != key.objectid)
                        break;
                if (btrfs_disk_key_type(&item->key) != BTRFS_DIR_ITEM_KEY)
                        continue;
                if (btrfs_disk_key_offset(&item->key) < filp->f_pos)
                        continue;

                advance = 1;
                di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
                over = filldir(dirent, (const char *)(di + 1),
                               btrfs_dir_name_len(di),
                               btrfs_disk_key_offset(&item->key),
                               btrfs_dir_objectid(di), d_type);
                if (over) {
                        filp->f_pos = btrfs_disk_key_offset(&item->key);
                        break;
                }
                filp->f_pos = btrfs_disk_key_offset(&item->key) + 1;
        }
        ret = 0;
err:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        mutex_unlock(&root->fs_info->fs_mutex);
        return ret;
}

static void btrfs_put_super (struct super_block * sb)
{
        struct btrfs_root *root = btrfs_sb(sb);
        int ret;

        ret = close_ctree(root);
        if (ret) {
                printk("close ctree returns %d\n", ret);
        }
        sb->s_fs_info = NULL;
}

static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
{
        struct inode * inode;
        struct dentry * root_dentry;
        struct btrfs_super_block *disk_super;
        struct btrfs_root *root;

        sb->s_maxbytes = MAX_LFS_FILESIZE;
        sb->s_magic = BTRFS_SUPER_MAGIC;
        sb->s_op = &btrfs_super_ops;
        sb->s_time_gran = 1;

        root = open_ctree(sb);

        if (!root) {
                printk("btrfs: open_ctree failed\n");
                return -EIO;
        }
        sb->s_fs_info = root;
        disk_super = root->fs_info->disk_super;
        printk("read in super total blocks %Lu root %Lu\n",
               btrfs_super_total_blocks(disk_super),
               btrfs_super_root_dir(disk_super));

        inode = iget_locked(sb, btrfs_super_root_dir(disk_super));
        if (!inode)
                return -ENOMEM;
        if (inode->i_state & I_NEW) {
                btrfs_read_locked_inode(inode);
                unlock_new_inode(inode);
        }

        root_dentry = d_alloc_root(inode);
        if (!root_dentry) {
                iput(inode);
                return -ENOMEM;
        }
        sb->s_root = root_dentry;

        return 0;
}

static void fill_inode_item(struct btrfs_inode_item *item,
                            struct inode *inode)
{
        btrfs_set_inode_uid(item, inode->i_uid);
        btrfs_set_inode_gid(item, inode->i_gid);
        btrfs_set_inode_size(item, inode->i_size);
        btrfs_set_inode_mode(item, inode->i_mode);
        btrfs_set_inode_nlink(item, inode->i_nlink);
        btrfs_set_timespec_sec(&item->atime, inode->i_atime.tv_sec);
        btrfs_set_timespec_nsec(&item->atime, inode->i_atime.tv_nsec);
        btrfs_set_timespec_sec(&item->mtime, inode->i_mtime.tv_sec);
        btrfs_set_timespec_nsec(&item->mtime, inode->i_mtime.tv_nsec);
        btrfs_set_timespec_sec(&item->ctime, inode->i_ctime.tv_sec);
        btrfs_set_timespec_nsec(&item->ctime, inode->i_ctime.tv_nsec);
        btrfs_set_inode_nblocks(item, inode->i_blocks);
        btrfs_set_inode_generation(item, inode->i_generation);
        check_inode(inode);
}

static int btrfs_update_inode(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root,
                              struct inode *inode)
{
        struct btrfs_inode_item *inode_item;
        struct btrfs_path *path;
        int ret;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);

        ret = btrfs_lookup_inode(trans, root, path, inode->i_ino, 1);
        if (ret) {
                if (ret > 0)
                        ret = -ENOENT;
                goto failed;
        }

        inode_item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
                                  path->slots[0],
                                  struct btrfs_inode_item);

        fill_inode_item(inode_item, inode);
        btrfs_mark_buffer_dirty(path->nodes[0]);
failed:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        check_inode(inode);
        return 0;
}

static int btrfs_write_inode(struct inode *inode, int wait)
{
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        struct btrfs_trans_handle *trans;
        int ret;

        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        ret = btrfs_update_inode(trans, root, inode);
        if (wait)
                btrfs_commit_transaction(trans, root);
        else
                btrfs_end_transaction(trans, root);
        mutex_unlock(&root->fs_info->fs_mutex);
        check_inode(inode);
        return ret;
}

static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
                                     struct inode *dir, int mode)
{
        struct inode *inode;
        struct btrfs_inode_item inode_item;
        struct btrfs_root *root = btrfs_sb(dir->i_sb);
        struct btrfs_key key;
        int ret;
        u64 objectid;

        inode = new_inode(dir->i_sb);
        if (!inode)
                return ERR_PTR(-ENOMEM);

        check_inode(inode);
        ret = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
        BUG_ON(ret);

        inode->i_uid = current->fsuid;
        inode->i_gid = current->fsgid;
        inode->i_mode = mode;
        inode->i_ino = objectid;
        inode->i_blocks = 0;
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
        fill_inode_item(&inode_item, inode);

        key.objectid = objectid;
        key.flags = 0;
        key.offset = 0;
        btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
        ret = btrfs_insert_inode_map(trans, root, objectid, &key);
        BUG_ON(ret);

        ret = btrfs_insert_inode(trans, root, objectid, &inode_item);
        BUG_ON(ret);

        insert_inode_hash(inode);
        check_inode(inode);
        check_inode(dir);
        return inode;
}

static int btrfs_add_link(struct btrfs_trans_handle *trans,
                            struct dentry *dentry, struct inode *inode)
{
        int ret;
        ret = btrfs_insert_dir_item(trans, btrfs_sb(inode->i_sb),
                                    dentry->d_name.name, dentry->d_name.len,
                                    dentry->d_parent->d_inode->i_ino,
                                    inode->i_ino, 0);
        if (ret == 0) {
                dentry->d_parent->d_inode->i_size += dentry->d_name.len;
                ret = btrfs_update_inode(trans, btrfs_sb(inode->i_sb),
                                         dentry->d_parent->d_inode);
        }
        check_inode(inode);
        check_inode(dentry->d_parent->d_inode);
        return ret;
}

static int btrfs_add_nondir(struct btrfs_trans_handle *trans,
                            struct dentry *dentry, struct inode *inode)
{
        int err = btrfs_add_link(trans, dentry, inode);
        if (!err) {
                d_instantiate(dentry, inode);
                return 0;
        }
        if (err > 0)
                err = -EEXIST;
        check_inode(inode);
        return err;
}

static int btrfs_create(struct inode *dir, struct dentry *dentry,
                        int mode, struct nameidata *nd)
{
        struct btrfs_trans_handle *trans;
        struct btrfs_root *root = btrfs_sb(dir->i_sb);
        struct inode *inode;
        int err;
        int drop_inode = 0;

        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        inode = btrfs_new_inode(trans, dir, mode);
        err = PTR_ERR(inode);
        if (IS_ERR(inode))
                goto out_unlock;
        // FIXME mark the inode dirty
        err = btrfs_add_nondir(trans, dentry, inode);
        if (err)
                drop_inode = 1;
        else {
                inode->i_mapping->a_ops = &btrfs_aops;
                inode->i_fop = &btrfs_file_operations;
                inode->i_op = &btrfs_file_inode_operations;
        }
        dir->i_sb->s_dirt = 1;
out_unlock:
        btrfs_end_transaction(trans, root);
        mutex_unlock(&root->fs_info->fs_mutex);
        check_inode(inode);
        check_inode(dir);

        if (drop_inode) {
                inode_dec_link_count(inode);
                iput(inode);
        }
        return err;
}

static int btrfs_make_empty_dir(struct btrfs_trans_handle *trans,
                                struct inode *inode, struct inode *dir)
{
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        int ret;
        char buf[2];
        buf[0] = '.';
        buf[1] = '.';

        ret = btrfs_insert_dir_item(trans, root, buf, 1, inode->i_ino,
                                    inode->i_ino, 1);
        if (ret)
                goto error;
        ret = btrfs_insert_dir_item(trans, root, buf, 2, inode->i_ino,
                                    dir->i_ino, 1);
        if (ret)
                goto error;
        inode->i_size = 3;
        ret = btrfs_update_inode(trans, root, inode);
error:
        return ret;
}

static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        struct inode *inode;
        struct btrfs_trans_handle *trans;
        struct btrfs_root *root = btrfs_sb(dir->i_sb);
        int err = 0;
        int drop_on_err = 0;

        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        if (IS_ERR(trans)) {
                err = PTR_ERR(trans);
                goto out_unlock;
        }
        inode = btrfs_new_inode(trans, dir, S_IFDIR | mode);
        if (IS_ERR(inode)) {
                err = PTR_ERR(inode);
                goto out_fail;
        }
        drop_on_err = 1;
        inode->i_op = &btrfs_dir_inode_operations;
        inode->i_fop = &btrfs_dir_file_operations;

        err = btrfs_make_empty_dir(trans, inode, dir);
        if (err)
                goto out_fail;
        err = btrfs_add_link(trans, dentry, inode);
        if (err)
                goto out_fail;
        d_instantiate(dentry, inode);
        drop_on_err = 0;

out_fail:
        btrfs_end_transaction(trans, root);
out_unlock:
        mutex_unlock(&root->fs_info->fs_mutex);
        if (drop_on_err)
                iput(inode);
        return err;
}

static int btrfs_sync_fs(struct super_block *sb, int wait)
{
        struct btrfs_trans_handle *trans;
        struct btrfs_root *root;
        int ret;
        root = btrfs_sb(sb);

        sb->s_dirt = 0;
        if (!wait) {
                filemap_flush(root->fs_info->btree_inode->i_mapping);
                return 0;
        }
        filemap_write_and_wait(root->fs_info->btree_inode->i_mapping);
        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        ret = btrfs_commit_transaction(trans, root);
        sb->s_dirt = 0;
        BUG_ON(ret);
printk("btrfs sync_fs\n");
        mutex_unlock(&root->fs_info->fs_mutex);
        return 0;
}

static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
                           struct buffer_head *result, int create)
{
        int ret;
        int err = 0;
        u64 blocknr;
        u64 extent_start = 0;
        u64 extent_end = 0;
        u64 objectid = inode->i_ino;
        struct btrfs_path *path;
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        struct btrfs_trans_handle *trans = NULL;
        struct btrfs_file_extent_item *item;
        struct btrfs_leaf *leaf;
        struct btrfs_disk_key *found_key;

        path = btrfs_alloc_path();
        BUG_ON(!path);
        btrfs_init_path(path);
        if (create)
                trans = btrfs_start_transaction(root, 1);


        ret = btrfs_lookup_file_extent(trans, root, path,
                                       inode->i_ino,
                                       iblock << inode->i_blkbits, 0);
        if (ret < 0) {
                err = ret;
                goto out;
        }

        if (ret != 0) {
                if (path->slots[0] == 0) {
                        btrfs_release_path(root, path);
                        goto allocate;
                }
                path->slots[0]--;
        }

        item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                              struct btrfs_file_extent_item);
        leaf = btrfs_buffer_leaf(path->nodes[0]);
        blocknr = btrfs_file_extent_disk_blocknr(item);
        blocknr += btrfs_file_extent_offset(item);

        /* exact match found, use it */
        if (ret == 0) {
                err = 0;
                map_bh(result, inode->i_sb, blocknr);
                goto out;
        }

        /* are we inside the extent that was found? */
        found_key = &leaf->items[path->slots[0]].key;
        if (btrfs_disk_key_objectid(found_key) != objectid ||
            btrfs_disk_key_type(found_key) != BTRFS_EXTENT_DATA_KEY) {
                extent_end = 0;
                extent_start = 0;
                btrfs_release_path(root, path);
                goto allocate;
        }

        extent_start = btrfs_disk_key_offset(&leaf->items[path->slots[0]].key);
        extent_start = extent_start >> inode->i_blkbits;
        extent_start += btrfs_file_extent_offset(item);
        extent_end = extent_start + btrfs_file_extent_num_blocks(item);
        if (iblock >= extent_start && iblock < extent_end) {
                err = 0;
                map_bh(result, inode->i_sb, blocknr + iblock - extent_start);
                goto out;
        }
allocate:
        /* ok, create a new extent */
        if (!create) {
                err = 0;
                goto out;
        }
        ret = btrfs_alloc_file_extent(trans, root, objectid,
                                      iblock << inode->i_blkbits,
                                      1, extent_end, &blocknr);
        if (ret) {
                err = ret;
                goto out;
        }
        inode->i_blocks += inode->i_sb->s_blocksize >> 9;
        set_buffer_new(result);
        map_bh(result, inode->i_sb, blocknr);

out:
        btrfs_release_path(root, path);
        btrfs_free_path(path);
        if (trans)
                btrfs_end_transaction(trans, root);
        return err;
}

static int btrfs_get_block(struct inode *inode, sector_t iblock,
                           struct buffer_head *result, int create)
{
        int err;
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        mutex_lock(&root->fs_info->fs_mutex);
        err = btrfs_get_block_lock(inode, iblock, result, create);
        mutex_unlock(&root->fs_info->fs_mutex);
        return err;
}

static int btrfs_prepare_write(struct file *file, struct page *page,
                               unsigned from, unsigned to)
{
        WARN_ON(1);
        return nobh_prepare_write(page, from, to, btrfs_get_block);
}
static int btrfs_commit_write(struct file *file, struct page *page,
                               unsigned from, unsigned to)
{
        WARN_ON(1);
        return nobh_commit_write(file, page, from, to);
}

static void btrfs_write_super(struct super_block *sb)
{
        btrfs_sync_fs(sb, 1);
}

static int btrfs_readpage(struct file *file, struct page *page)
{
        return mpage_readpage(page, btrfs_get_block);
}

static int btrfs_readpages(struct file *file, struct address_space *mapping,
                           struct list_head *pages, unsigned nr_pages)
{
        return mpage_readpages(mapping, pages, nr_pages, btrfs_get_block);
}

static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
{
        return nobh_writepage(page, btrfs_get_block, wbc);
}

static void btrfs_truncate(struct inode *inode)
{
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        int ret;
        struct btrfs_trans_handle *trans;

        if (!S_ISREG(inode->i_mode))
                return;
        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
                return;

        nobh_truncate_page(inode->i_mapping, inode->i_size);

        /* FIXME, add redo link to tree so we don't leak on crash */
        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
        ret = btrfs_truncate_in_trans(trans, root, inode);
        BUG_ON(ret);
        ret = btrfs_end_transaction(trans, root);
        BUG_ON(ret);
        mutex_unlock(&root->fs_info->fs_mutex);
        mark_inode_dirty(inode);
}

static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
                                struct page **prepared_pages,
                                const char __user * buf)
{
        long page_fault = 0;
        int i;
        int offset = pos & (PAGE_CACHE_SIZE - 1);

        for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
                size_t count = min_t(size_t,
                                     PAGE_CACHE_SIZE - offset, write_bytes);
                struct page *page = prepared_pages[i];
                fault_in_pages_readable(buf, count);

                /* Copy data from userspace to the current page */
                kmap(page);
                page_fault = __copy_from_user(page_address(page) + offset,
                                              buf, count);
                /* Flush processor's dcache for this page */
                flush_dcache_page(page);
                kunmap(page);
                buf += count;
                write_bytes -= count;

                if (page_fault)
                        break;
        }
        return page_fault ? -EFAULT : 0;
}

static void btrfs_drop_pages(struct page **pages, size_t num_pages)
{
        size_t i;
        for (i = 0; i < num_pages; i++) {
                if (!pages[i])
                        break;
                unlock_page(pages[i]);
                mark_page_accessed(pages[i]);
                page_cache_release(pages[i]);
        }
}
static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                                   struct btrfs_root *root,
                                   struct file *file,
                                   struct page **pages,
                                   size_t num_pages,
                                   loff_t pos,
                                   size_t write_bytes)
{
        int i;
        int offset;
        int err = 0;
        int ret;
        int this_write;
        struct inode *inode = file->f_path.dentry->d_inode;

        for (i = 0; i < num_pages; i++) {
                offset = pos & (PAGE_CACHE_SIZE -1);
                this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
                /* FIXME, one block at a time */

                mutex_lock(&root->fs_info->fs_mutex);
                trans = btrfs_start_transaction(root, 1);
                btrfs_csum_file_block(trans, root, inode->i_ino,
                                      pages[i]->index << PAGE_CACHE_SHIFT,
                                      kmap(pages[i]), PAGE_CACHE_SIZE);
                kunmap(pages[i]);
                SetPageChecked(pages[i]);
                ret = btrfs_end_transaction(trans, root);
                BUG_ON(ret);
                mutex_unlock(&root->fs_info->fs_mutex);

                ret = nobh_commit_write(file, pages[i], offset,
                                         offset + this_write);
                pos += this_write;
                if (ret) {
                        err = ret;
                        goto failed;
                }
                WARN_ON(this_write > write_bytes);
                write_bytes -= this_write;
        }
failed:
        return err;
}

static int prepare_pages(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root,
                         struct file *file,
                         struct page **pages,
                         size_t num_pages,
                         loff_t pos,
                         size_t write_bytes)
{
        int i;
        unsigned long index = pos >> PAGE_CACHE_SHIFT;
        struct inode *inode = file->f_path.dentry->d_inode;
        int offset;
        int err = 0;
        int ret;
        int this_write;
        loff_t isize = i_size_read(inode);

        memset(pages, 0, num_pages * sizeof(struct page *));

        for (i = 0; i < num_pages; i++) {
                pages[i] = grab_cache_page(inode->i_mapping, index + i);
                if (!pages[i]) {
                        err = -ENOMEM;
                        goto failed_release;
                }
                offset = pos & (PAGE_CACHE_SIZE -1);
                this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
                ret = nobh_prepare_write(pages[i], offset,
                                         offset + this_write,
                                         btrfs_get_block);
                pos += this_write;
                if (ret) {
                        err = ret;
                        goto failed_truncate;
                }
                WARN_ON(this_write > write_bytes);
                write_bytes -= this_write;
        }
        return 0;

failed_release:
        btrfs_drop_pages(pages, num_pages);
        return err;

failed_truncate:
        btrfs_drop_pages(pages, num_pages);
        if (pos > isize)
                vmtruncate(inode, isize);
        return err;
}

static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        loff_t pos;
        size_t num_written = 0;
        int err = 0;
        int ret = 0;
        struct inode *inode = file->f_path.dentry->d_inode;
        struct btrfs_root *root = btrfs_sb(inode->i_sb);
        struct page *pages[1];

        if (file->f_flags & O_DIRECT)
                return -EINVAL;
        pos = *ppos;

        vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
        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;
        if (count == 0)
                goto out;
        err = remove_suid(file->f_path.dentry);
        if (err)
                goto out;
        file_update_time(file);
        mutex_lock(&inode->i_mutex);
        while(count > 0) {
                size_t offset = pos & (PAGE_CACHE_SIZE - 1);
                size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
                size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
                                        PAGE_CACHE_SHIFT;
                ret = prepare_pages(NULL, root, file, pages, num_pages,
                                    pos, write_bytes);
                BUG_ON(ret);
                ret = btrfs_copy_from_user(pos, num_pages,
                                           write_bytes, pages, buf);
                BUG_ON(ret);

                ret = dirty_and_release_pages(NULL, root, file, pages,
                                              num_pages, pos, write_bytes);
                BUG_ON(ret);
                btrfs_drop_pages(pages, num_pages);

                buf += write_bytes;
                count -= write_bytes;
                pos += write_bytes;
                num_written += write_bytes;

                balance_dirty_pages_ratelimited(inode->i_mapping);
                cond_resched();
        }
        mutex_unlock(&inode->i_mutex);
out:
        *ppos = pos;
        current->backing_dev_info = NULL;
        return num_written ? num_written : err;
}

static int btrfs_read_actor(read_descriptor_t *desc, struct page *page,
                        unsigned long offset, unsigned long size)
{
        char *kaddr;
        unsigned long left, count = desc->count;

        if (size > count)
                size = count;

        if (!PageChecked(page)) {
                /* FIXME, do it per block */
                struct btrfs_root *root = btrfs_sb(page->mapping->host->i_sb);
                int ret = btrfs_csum_verify_file_block(root,
                                          page->mapping->host->i_ino,
                                          page->index << PAGE_CACHE_SHIFT,
                                          kmap(page), PAGE_CACHE_SIZE);
                if (ret) {
                        printk("failed to verify ino %lu page %lu\n",
                               page->mapping->host->i_ino,
                               page->index);
                        memset(page_address(page), 0, PAGE_CACHE_SIZE);
                }
                SetPageChecked(page);
                kunmap(page);
        }
        /*
         * Faults on the destination of a read are common, so do it before
         * taking the kmap.
         */
        if (!fault_in_pages_writeable(desc->arg.buf, size)) {
                kaddr = kmap_atomic(page, KM_USER0);
                left = __copy_to_user_inatomic(desc->arg.buf,
                                                kaddr + offset, size);
                kunmap_atomic(kaddr, KM_USER0);
                if (left == 0)
                        goto success;
        }

        /* Do it the slow way */
        kaddr = kmap(page);
        left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
        kunmap(page);

        if (left) {
                size -= left;
                desc->error = -EFAULT;
        }
success:
        desc->count = count - size;
        desc->written += size;
        desc->arg.buf += size;
        return size;
}

/**
 * btrfs_file_aio_read - filesystem read routine
 * @iocb:       kernel I/O control block
 * @iov:        io vector request
 * @nr_segs:    number of segments in the iovec
 * @pos:        current file position
 */
static ssize_t btrfs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
                                   unsigned long nr_segs, loff_t pos)
{
        struct file *filp = iocb->ki_filp;
        ssize_t retval;
        unsigned long seg;
        size_t count;
        loff_t *ppos = &iocb->ki_pos;

        count = 0;
        for (seg = 0; seg < nr_segs; seg++) {
                const struct iovec *iv = &iov[seg];

                /*
                 * If any segment has a negative length, or the cumulative
                 * length ever wraps negative then return -EINVAL.
                 */
                count += iv->iov_len;
                if (unlikely((ssize_t)(count|iv->iov_len) < 0))
                        return -EINVAL;
                if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
                        continue;
                if (seg == 0)
                        return -EFAULT;
                nr_segs = seg;
                count -= iv->iov_len;   /* This segment is no good */
                break;
        }
        retval = 0;
        if (count) {
                for (seg = 0; seg < nr_segs; seg++) {
                        read_descriptor_t desc;

                        desc.written = 0;
                        desc.arg.buf = iov[seg].iov_base;
                        desc.count = iov[seg].iov_len;
                        if (desc.count == 0)
                                continue;
                        desc.error = 0;
                        do_generic_file_read(filp, ppos, &desc,
                                             btrfs_read_actor);
                        retval += desc.written;
                        if (desc.error) {
                                retval = retval ?: desc.error;
                                break;
                        }
                }
        }
        return retval;
}

static struct kmem_cache *btrfs_inode_cachep;
struct kmem_cache *btrfs_trans_handle_cachep;
struct kmem_cache *btrfs_transaction_cachep;
struct kmem_cache *btrfs_bit_radix_cachep;
struct kmem_cache *btrfs_path_cachep;

/*
 * Called inside transaction, so use GFP_NOFS
 */
static struct inode *btrfs_alloc_inode(struct super_block *sb)
{
        struct btrfs_inode *ei;

        ei = kmem_cache_alloc(btrfs_inode_cachep, GFP_NOFS);
        if (!ei)
                return NULL;
        ei->magic = 0xDEADBEEF;
        ei->magic2 = 0xDEADBEAF;
        return &ei->vfs_inode;
}

static void btrfs_destroy_inode(struct inode *inode)
{
        struct btrfs_inode *ei = BTRFS_I(inode);
        WARN_ON(ei->magic != 0xDEADBEEF);
        WARN_ON(ei->magic2 != 0xDEADBEAF);
        WARN_ON(!list_empty(&inode->i_dentry));
        WARN_ON(inode->i_ino == 1);
        WARN_ON(inode->i_data.nrpages);

        ei->magic = 0;
        ei->magic2 = 0;
        kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
}

static void init_once(void * foo, struct kmem_cache * cachep,
                      unsigned long flags)
{
        struct btrfs_inode *ei = (struct btrfs_inode *) foo;

        if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
            SLAB_CTOR_CONSTRUCTOR) {
                inode_init_once(&ei->vfs_inode);
        }
}

static int init_inodecache(void)
{
        btrfs_inode_cachep = kmem_cache_create("btrfs_inode_cache",
                                             sizeof(struct btrfs_inode),
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_MEM_SPREAD),
                                             init_once, NULL);
        btrfs_trans_handle_cachep = kmem_cache_create("btrfs_trans_handle_cache",
                                             sizeof(struct btrfs_trans_handle),
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_MEM_SPREAD),
                                             NULL, NULL);
        btrfs_transaction_cachep = kmem_cache_create("btrfs_transaction_cache",
                                             sizeof(struct btrfs_transaction),
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_MEM_SPREAD),
                                             NULL, NULL);
        btrfs_path_cachep = kmem_cache_create("btrfs_path_cache",
                                             sizeof(struct btrfs_transaction),
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_MEM_SPREAD),
                                             NULL, NULL);
        btrfs_bit_radix_cachep = kmem_cache_create("btrfs_radix",
                                             256,
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_MEM_SPREAD |
                                                SLAB_DESTROY_BY_RCU),
                                             NULL, NULL);
        if (btrfs_inode_cachep == NULL || btrfs_trans_handle_cachep == NULL ||
            btrfs_transaction_cachep == NULL || btrfs_bit_radix_cachep == NULL)
                return -ENOMEM;
        return 0;
}

static void destroy_inodecache(void)
{
        kmem_cache_destroy(btrfs_inode_cachep);
        kmem_cache_destroy(btrfs_trans_handle_cachep);
        kmem_cache_destroy(btrfs_transaction_cachep);
        kmem_cache_destroy(btrfs_bit_radix_cachep);
        kmem_cache_destroy(btrfs_path_cachep);
}

static int btrfs_get_sb(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
        return get_sb_bdev(fs_type, flags, dev_name, data,
                           btrfs_fill_super, mnt);
}

static struct file_system_type btrfs_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "btrfs",
        .get_sb         = btrfs_get_sb,
        .kill_sb        = kill_block_super,
        .fs_flags       = FS_REQUIRES_DEV,
};

static struct super_operations btrfs_super_ops = {
        .statfs         = simple_statfs,
        .delete_inode   = btrfs_delete_inode,
        .put_super      = btrfs_put_super,
        .read_inode     = btrfs_read_locked_inode,
        .write_super    = btrfs_write_super,
        .sync_fs        = btrfs_sync_fs,
        .write_inode    = btrfs_write_inode,
        .alloc_inode    = btrfs_alloc_inode,
        .destroy_inode  = btrfs_destroy_inode,
};

static struct inode_operations btrfs_dir_inode_operations = {
        .lookup         = btrfs_lookup,
        .create         = btrfs_create,
        .unlink         = btrfs_unlink,
        .mkdir          = btrfs_mkdir,
        .rmdir          = btrfs_rmdir,
};

static struct file_operations btrfs_dir_file_operations = {
        .llseek         = generic_file_llseek,
        .read           = generic_read_dir,
        .readdir        = btrfs_readdir,
};

static struct address_space_operations btrfs_aops = {
        .readpage       = btrfs_readpage,
        .readpages      = btrfs_readpages,
        .writepage      = btrfs_writepage,
        .sync_page      = block_sync_page,
        .prepare_write  = btrfs_prepare_write,
        .commit_write   = btrfs_commit_write,
};

static struct inode_operations btrfs_file_inode_operations = {
        .truncate       = btrfs_truncate,
};

static struct file_operations btrfs_file_operations = {
        .llseek         = generic_file_llseek,
        .read           = do_sync_read,
        .aio_read       = btrfs_file_aio_read,
        .write          = btrfs_file_write,
        .mmap           = generic_file_mmap,
        .open           = generic_file_open,
};

static int __init init_btrfs_fs(void)
{
        int err;
        printk("btrfs loaded!\n");
        err = init_inodecache();
        if (err)
                return err;
        return register_filesystem(&btrfs_fs_type);
}

static void __exit exit_btrfs_fs(void)
{
        destroy_inodecache();
        unregister_filesystem(&btrfs_fs_type);
        printk("btrfs unloaded\n");
}

module_init(init_btrfs_fs)
module_exit(exit_btrfs_fs)

MODULE_LICENSE("GPL");