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

This will be used by the inode lookup ioctl.

Signed-off-by: TARUISI Hiroaki <taruishi.hiroak@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
TARUISI Hiroaki 2009-11-18 05:42:14 +00:00 committed by Chris Mason
parent da495ecc0f
commit 98d377a089
1 changed files with 92 additions and 0 deletions
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92
fs/btrfs/ioctl.c
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@ -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 @@ out:
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)
{