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Commit 98d377a0 authored by TARUISI Hiroaki's avatar TARUISI Hiroaki Committed by Chris Mason
Browse files

Btrfs: add a function to lookup a directory path by following backrefs 



This will be used by the inode lookup ioctl.

Signed-off-by: default avatarTARUISI Hiroaki <taruishi.hiroak@jp.fujitsu.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent da495ecc

fs/btrfs/ioctl.c

+92 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ 
#include "print-tree.h"

#include "volumes.h"

#include "locking.h"

#include "ctree.h"



/* Mask out flags that are inappropriate for the given type of inode. */

static inline __u32 btrfs_mask_flags(umode_t mode, __u32 flags)
@@ -743,6 +744,97 @@ static noinline int may_destroy_subvol(struct btrfs_root *root) 
	return ret;

}



/*

  Search INODE_REFs to identify path name of 'dirid' directory

  in a 'tree_id' tree. and sets path name to 'name'.

*/

static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,

				u64 tree_id, u64 dirid, char *name)

{

	struct btrfs_root *root;

	struct btrfs_key key;

	char *name_stack, *ptr;

	int ret = -1;

	int slot;

	int len;

	int total_len = 0;

	struct btrfs_inode_ref *iref;

	struct extent_buffer *l;

	struct btrfs_path *path;



	if (dirid == BTRFS_FIRST_FREE_OBJECTID) {

		name[0]='\0';

		return 0;

	}



	path = btrfs_alloc_path();

	if (!path)

		return -ENOMEM;



	name_stack = kzalloc(BTRFS_PATH_NAME_MAX+1, GFP_NOFS);

	if (!name_stack) {

		btrfs_free_path(path);

		return -ENOMEM;

	}



	ptr = &name_stack[BTRFS_PATH_NAME_MAX];



	key.objectid = tree_id;

	key.type = BTRFS_ROOT_ITEM_KEY;

	key.offset = (u64)-1;

	root = btrfs_read_fs_root_no_name(info, &key);

	if (IS_ERR(root)) {

		printk(KERN_ERR "could not find root %llu\n", tree_id);

		return -ENOENT;

	}



	key.objectid = dirid;

	key.type = BTRFS_INODE_REF_KEY;

	key.offset = 0;



	while(1) {

		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);

		if (ret < 0)

			goto out;



		l = path->nodes[0];

		slot = path->slots[0];

		btrfs_item_key_to_cpu(l, &key, slot);



		if (ret > 0 && (key.objectid != dirid ||

					key.type != BTRFS_INODE_REF_KEY))

			goto out;



		iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);

		len = btrfs_inode_ref_name_len(l, iref);

		ptr -= len + 1;

		total_len += len + 1;

		if (ptr < name_stack)

			goto out;



		*(ptr + len) = '/';

		read_extent_buffer(l, ptr,(unsigned long)(iref + 1), len);



		if (key.offset == BTRFS_FIRST_FREE_OBJECTID)

			break;



		btrfs_release_path(root, path);

		key.objectid = key.offset;

		key.offset = 0;

		dirid = key.objectid;



	}

	if (ptr < name_stack)

		goto out;

	strncpy(name, ptr, total_len);

	name[total_len]='\0';

	ret = 0;

out:

	btrfs_free_path(path);

	kfree(name_stack);

	return ret;

}



static noinline int btrfs_ioctl_snap_destroy(struct file *file,

					     void __user *arg)

{