C++ BTRFS_I函数代码示例

static int btrfs_defrag_file(struct file *file,
			     struct btrfs_ioctl_defrag_range_args *range)
{
	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;
	u64 last_len = 0;
	u64 skip = 0;
	u64 defrag_end = 0;
	unsigned long i;
	int ret;

	if (inode->i_size == 0)
		return 0;

	if (range->start + range->len > range->start) {
		last_index = min_t(u64, inode->i_size - 1,
			 range->start + range->len - 1) >> PAGE_CACHE_SHIFT;
	} else {

/*
 * @value: "" makes the attribute to empty, NULL removes it
 */
int __btrfs_setxattr(struct btrfs_trans_handle *trans,
		     struct inode *inode, const char *name,
		     const void *value, size_t size, int flags)
{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	int ret;

	if (trans)
		return do_setxattr(trans, inode, name, value, size, flags);

	trans = btrfs_start_transaction(root, 2);
	if (IS_ERR(trans))
		return PTR_ERR(trans);

	ret = do_setxattr(trans, inode, name, value, size, flags);
	if (ret)
		goto out;

	inode_inc_iversion(inode);
	inode->i_ctime = current_fs_time(inode->i_sb);
	set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
	ret = btrfs_update_inode(trans, root, inode);
	BUG_ON(ret);
out:
	btrfs_end_transaction(trans, root);
	return ret;
}

int btrfs_getxattr(struct inode *inode, const char *name,
				void *buffer, size_t size)
{
	struct btrfs_dir_item *di;
	struct btrfs_root *root = BTRFS_I(inode)->root;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	int ret = 0;
	unsigned long data_ptr;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	/* lookup the xattr by name */
	di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)),
			name, strlen(name), 0);
	if (!di) {
		ret = -ENODATA;
		goto out;
	} else if (IS_ERR(di)) {
		ret = PTR_ERR(di);
		goto out;
	}

	leaf = path->nodes[0];
	/* if size is 0, that means we want the size of the attr */
	if (!size) {
		ret = btrfs_dir_data_len(leaf, di);
		goto out;
	}

	/* now get the data out of our dir_item */
	if (btrfs_dir_data_len(leaf, di) > size) {
		ret = -ERANGE;
		goto out;
	}

	/*
	 * The way things are packed into the leaf is like this
	 * |struct btrfs_dir_item|name|data|
	 * where name is the xattr name, so security.foo, and data is the
	 * content of the xattr.  data_ptr points to the location in memory
	 * where the data starts in the in memory leaf
	 */
	data_ptr = (unsigned long)((char *)(di + 1) +
				   btrfs_dir_name_len(leaf, di));
	read_extent_buffer(leaf, buffer, data_ptr,
			   btrfs_dir_data_len(leaf, di));
	ret = btrfs_dir_data_len(leaf, di);

out:
	btrfs_free_path(path);
	return ret;
}

/*
 * Create a new subvolume below @parent.  This is largely modeled after
 * sys_mkdirat and vfs_mkdir, but we only do a single component lookup
 * inside this filesystem so it's quite a bit simpler.
 */
static noinline int btrfs_mksubvol(struct path *parent,
				   char *name, int namelen,
				   struct btrfs_root *snap_src)
{
	struct inode *dir  = parent->dentry->d_inode;
	struct dentry *dentry;
	int error;

	mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);

	dentry = lookup_one_len(name, parent->dentry, namelen);
	error = PTR_ERR(dentry);
	if (IS_ERR(dentry))
		goto out_unlock;

	error = -EEXIST;
	if (dentry->d_inode)
		goto out_dput;

	error = mnt_want_write(parent->mnt);
	if (error)
		goto out_dput;

	error = btrfs_may_create(dir, dentry);
	if (error)
		goto out_drop_write;

	down_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);

	if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
		goto out_up_read;

	if (snap_src) {
		error = create_snapshot(snap_src, dentry,
					name, namelen);
	} else {
		error = create_subvol(BTRFS_I(dir)->root, dentry,
				      name, namelen);
	}
	if (!error)
		fsnotify_mkdir(dir, dentry);
out_up_read:
	up_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);
out_drop_write:
	mnt_drop_write(parent->mnt);
out_dput:
	dput(dentry);
out_unlock:
	mutex_unlock(&dir->i_mutex);
	return error;
}

static struct dentry *btrfs_get_parent(struct dentry *child)
{
	struct inode *dir = d_inode(child);
	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
	struct btrfs_root *root = BTRFS_I(dir)->root;
	struct btrfs_path *path;
	struct extent_buffer *leaf;
	struct btrfs_root_ref *ref;
	struct btrfs_key key;
	struct btrfs_key found_key;
	int ret;

	path = btrfs_alloc_path();
	if (!path)
		return ERR_PTR(-ENOMEM);

	if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
		key.objectid = root->root_key.objectid;
		key.type = BTRFS_ROOT_BACKREF_KEY;
		key.offset = (u64)-1;
		root = fs_info->tree_root;
	} else {
		key.objectid = btrfs_ino(BTRFS_I(dir));
		key.type = BTRFS_INODE_REF_KEY;
		key.offset = (u64)-1;
	}

	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0)
		goto fail;

	BUG_ON(ret == 0); /* Key with offset of -1 found */
	if (path->slots[0] == 0) {
		ret = -ENOENT;
		goto fail;
	}

	path->slots[0]--;
	leaf = path->nodes[0];

	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
	if (found_key.objectid != key.objectid || found_key.type != key.type) {
		ret = -ENOENT;
		goto fail;
	}

	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
		ref = btrfs_item_ptr(leaf, path->slots[0],
				     struct btrfs_root_ref);
		key.objectid = btrfs_root_ref_dirid(leaf, ref);
	} else {

static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
			   int connectable)
{
	struct btrfs_fid *fid = (struct btrfs_fid *)fh;
	struct inode *inode = dentry->d_inode;
	int len = *max_len;
	int type;

	if (connectable && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
		*max_len = BTRFS_FID_SIZE_CONNECTABLE;
		return 255;
	} else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
		*max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
		return 255;
	}

	len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
	type = FILEID_BTRFS_WITHOUT_PARENT;

	fid->objectid = btrfs_ino(inode);
	fid->root_objectid = BTRFS_I(inode)->root->objectid;
	fid->gen = inode->i_generation;

	if (connectable && !S_ISDIR(inode->i_mode)) {
		struct inode *parent;
		u64 parent_root_id;

		spin_lock(&dentry->d_lock);

		parent = dentry->d_parent->d_inode;
		fid->parent_objectid = BTRFS_I(parent)->location.objectid;
		fid->parent_gen = parent->i_generation;
		parent_root_id = BTRFS_I(parent)->root->objectid;

		spin_unlock(&dentry->d_lock);

		if (parent_root_id != fid->root_objectid) {
			fid->parent_root_objectid = parent_root_id;
			len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
			type = FILEID_BTRFS_WITH_PARENT_ROOT;
		} else {
			len = BTRFS_FID_SIZE_CONNECTABLE;
			type = FILEID_BTRFS_WITH_PARENT;
		}
	}

	*max_len = len;
	return type;
}

int __btrfs_setxattr(struct btrfs_trans_handle *trans,
		     struct inode *inode, const char *name,
		     const void *value, size_t size, int flags)
{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	int ret;

	if (trans)
		return do_setxattr(trans, inode, name, value, size, flags);

	ret = btrfs_reserve_metadata_space(root, 2);
	if (ret)
		return ret;

	trans = btrfs_start_transaction(root, 1);
	if (!trans) {
		ret = -ENOMEM;
		goto out;
	}
	btrfs_set_trans_block_group(trans, inode);

	ret = do_setxattr(trans, inode, name, value, size, flags);
	if (ret)
		goto out;

	inode->i_ctime = CURRENT_TIME;
	ret = btrfs_update_inode(trans, root, inode);
	BUG_ON(ret);
out:
	btrfs_end_transaction_throttle(trans, root);
	btrfs_unreserve_metadata_space(root, 2);
	return ret;
}

int btrfs_removexattr(struct dentry *dentry, const char *name)
{
	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

	/*
	 * The permission on security.* and system.* is not checked
	 * in permission().
	 */
	if (btrfs_root_readonly(root))
		return -EROFS;

	/*
	 * If this is a request for a synthetic attribute in the system.*
	 * namespace use the generic infrastructure to resolve a handler
	 * for it via sb->s_xattr.
	 */
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return generic_removexattr(dentry, name);

	if (!btrfs_is_valid_xattr(name))
		return -EOPNOTSUPP;

	return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
				XATTR_REPLACE);
}

int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
		   size_t size, int flags)
{
	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

	/*
	 * The permission on security.* and system.* is not checked
	 * in permission().
	 */
	if (btrfs_root_readonly(root))
		return -EROFS;

	/*
	 * If this is a request for a synthetic attribute in the system.*
	 * namespace use the generic infrastructure to resolve a handler
	 * for it via sb->s_xattr.
	 */
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return generic_setxattr(dentry, name, value, size, flags);

	if (!btrfs_is_valid_xattr(name))
		return -EOPNOTSUPP;

	if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
		return btrfs_set_prop(dentry->d_inode, name,
				      value, size, flags);

	if (size == 0)
		value = "";  /* empty EA, do not remove */

	return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
				flags);
}

int btrfs_removexattr(struct dentry *dentry, const char *name)
{
	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

	/*
                                                            
                    
  */
	if (btrfs_root_readonly(root))
		return -EROFS;

	/*
                                                                  
                                                                 
                           
  */
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return generic_removexattr(dentry, name);

	if (!btrfs_is_valid_xattr(name))
		return -EOPNOTSUPP;

	return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
				XATTR_REPLACE);
}

int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
		   size_t size, int flags)
{
	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;

	/*
                                                            
                    
  */
	if (btrfs_root_readonly(root))
		return -EROFS;

	/*
                                                                  
                                                                 
                           
  */
	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
		return generic_setxattr(dentry, name, value, size, flags);

	if (!btrfs_is_valid_xattr(name))
		return -EOPNOTSUPP;

	if (size == 0)
		value = "";  /*                         */

	return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
				flags);
}

/*
 * @value: "" makes the attribute to empty, NULL removes it
 */
int __btrfs_setxattr(struct btrfs_trans_handle *trans,
		     struct inode *inode, const char *name,
		     const void *value, size_t size, int flags)
{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	int ret;

	if (trans)
		return do_setxattr(trans, inode, name, value, size, flags);

	trans = btrfs_start_transaction(root, 2);
	if (IS_ERR(trans))
		return PTR_ERR(trans);

	ret = do_setxattr(trans, inode, name, value, size, flags);
	if (ret)
		goto out;

	inode->i_ctime = CURRENT_TIME;
	ret = btrfs_update_inode(trans, root, inode);
	BUG_ON(ret);
out:
	btrfs_end_transaction_throttle(trans, root);
	return ret;
}

/*
 * after copy_from_user, pages need to be dirtied and we need to make
 * sure holes are created between the current EOF and the start of
 * any next extents (if required).
 *
 * this also makes the decision about creating an inline extent vs
 * doing real data extents, marking pages dirty and delalloc as required.
 */
static noinline 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 err = 0;
	int i;
	struct inode *inode = fdentry(file)->d_inode;
	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
	u64 hint_byte;
	u64 num_bytes;
	u64 start_pos;
	u64 end_of_last_block;
	u64 end_pos = pos + write_bytes;
	loff_t isize = i_size_read(inode);

	start_pos = pos & ~((u64)root->sectorsize - 1);
	num_bytes = (write_bytes + pos - start_pos +
		    root->sectorsize - 1) & ~((u64)root->sectorsize - 1);

	end_of_last_block = start_pos + num_bytes - 1;

	lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
	trans = btrfs_join_transaction(root, 1);
	if (!trans) {
		err = -ENOMEM;
		goto out_unlock;
	}
	btrfs_set_trans_block_group(trans, inode);
	hint_byte = 0;

	set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);

	/* check for reserved extents on each page, we don't want
	 * to reset the delalloc bit on things that already have
	 * extents reserved.
	 */
	btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
	for (i = 0; i < num_pages; i++) {
		struct page *p = pages[i];
		SetPageUptodate(p);
		ClearPageChecked(p);
		set_page_dirty(p);
	}
	if (end_pos > isize) {
		i_size_write(inode, end_pos);
		/* we've only changed i_size in ram, and we haven't updated
		 * the disk i_size.  There is no need to log the inode
		 * at this time.
		 */
	}
	err = btrfs_end_transaction(trans, root);
out_unlock:
	unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
	return err;
}

int btrfs_removexattr(struct dentry *dentry, const char *name)
{
	struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;

	if (btrfs_root_readonly(root))
		return -EROFS;
	return generic_removexattr(dentry, name);
}

/*
 * Inherit flags from the parent inode.
 *
 * Unlike extN we don't have any flags we don't want to inherit currently.
 */
void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
{
	unsigned int flags;

	if (!dir)
		return;

	flags = BTRFS_I(dir)->flags;

	if (S_ISREG(inode->i_mode))
		flags &= ~BTRFS_INODE_DIRSYNC;
	else if (!S_ISDIR(inode->i_mode))
		flags &= (BTRFS_INODE_NODUMP | BTRFS_INODE_NOATIME);

	BTRFS_I(inode)->flags = flags;
	btrfs_update_iflags(inode);
}