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fs: btrfs: Introduce function to resolve path in one subvolume

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This patch introduces a new function, get_path_in_subvolume(), which
resolves inode number into path inside a subvolume.

This function will be later used for btrfs subvolume list functionality.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
This commit is contained in:
Qu Wenruo 2020-06-24 18:03:12 +02:00 committed by Tom Rini
parent e3427184f3
commit 8098da7094
2 changed files with 68 additions and 1 deletions
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1
fs/btrfs/compat.h
View File

@ -18,6 +18,7 @@
/* No <linux/limits.h> so have to define it here */
#define XATTR_NAME_MAX 255
#define PATH_MAX 4096
/*
* Macros to generate set/get funcs for the struct fields

68
fs/btrfs/subvolume.c
View File

@ -5,8 +5,74 @@
* 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
*/
#include "btrfs.h"
#include <malloc.h>
#include "ctree.h"
#include "btrfs.h"
/*
* Resolve the path of ino inside subvolume @root into @path_ret.
*
* @path_ret must be at least PATH_MAX size.
*/
static int get_path_in_subvol(struct btrfs_root *root, u64 ino, char *path_ret)
{
struct btrfs_path path;
struct btrfs_key key;
char *tmp;
u64 cur = ino;
int ret = 0;
tmp = malloc(PATH_MAX);
if (!tmp)
return -ENOMEM;
tmp[0] = '\0';
btrfs_init_path(&path);
while (cur != BTRFS_FIRST_FREE_OBJECTID) {
struct btrfs_inode_ref *iref;
int name_len;
btrfs_release_path(&path);
key.objectid = cur;
key.type = BTRFS_INODE_REF_KEY;
key.offset = (u64)-1;
ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
/* Impossible */
if (ret == 0)
ret = -EUCLEAN;
if (ret < 0)
goto out;
ret = btrfs_previous_item(root, &path, cur,
BTRFS_INODE_REF_KEY);
if (ret > 0)
ret = -ENOENT;
if (ret < 0)
goto out;
strncpy(tmp, path_ret, PATH_MAX);
iref = btrfs_item_ptr(path.nodes[0], path.slots[0],
struct btrfs_inode_ref);
name_len = btrfs_inode_ref_name_len(path.nodes[0],
iref);
if (name_len > BTRFS_NAME_LEN) {
ret = -ENAMETOOLONG;
goto out;
}
read_extent_buffer(path.nodes[0], path_ret,
(unsigned long)(iref + 1), name_len);
path_ret[name_len] = '/';
path_ret[name_len + 1] = '\0';
strncat(path_ret, tmp, PATH_MAX);
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
cur = key.offset;
}
out:
btrfs_release_path(&path);
free(tmp);
return ret;
}
static int get_subvol_name(u64 subvolid, char *name, int max_len)
{