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fs: btrfs: Introduce function to resolve the path of one subvolume

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This patch introduces a new function, list_one_subvol(), which will
resolve the path to FS_TREE of one subvolume.

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 18:03:13 +02:00 committed by Tom Rini
parent 8098da7094
commit f48615276b
1 changed files with 81 additions and 0 deletions
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81
fs/btrfs/subvolume.c
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@ -8,6 +8,7 @@
#include <malloc.h>
#include "ctree.h"
#include "btrfs.h"
#include "disk-io.h"
/*
* Resolve the path of ino inside subvolume @root into @path_ret.
@ -74,6 +75,86 @@ out:
return ret;
}
static int list_one_subvol(struct btrfs_root *root, char *path_ret)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_path path;
struct btrfs_key key;
char *tmp;
u64 cur = root->root_key.objectid;
int ret = 0;
tmp = malloc(PATH_MAX);
if (!tmp)
return -ENOMEM;
tmp[0] = '\0';
path_ret[0] = '\0';
btrfs_init_path(&path);
while (cur != BTRFS_FS_TREE_OBJECTID) {
struct btrfs_root_ref *rr;
struct btrfs_key location;
int name_len;
u64 ino;
key.objectid = cur;
key.type = BTRFS_ROOT_BACKREF_KEY;
key.offset = (u64)-1;
btrfs_release_path(&path);
ret = btrfs_search_slot(NULL, tree_root, &key, &path, 0, 0);
if (ret == 0)
ret = -EUCLEAN;
if (ret < 0)
goto out;
ret = btrfs_previous_item(tree_root, &path, cur,
BTRFS_ROOT_BACKREF_KEY);
if (ret > 0)
ret = -ENOENT;
if (ret < 0)
goto out;
/* Get the subvolume name */
rr = btrfs_item_ptr(path.nodes[0], path.slots[0],
struct btrfs_root_ref);
strncpy(tmp, path_ret, PATH_MAX);
name_len = btrfs_root_ref_name_len(path.nodes[0], rr);
if (name_len > BTRFS_NAME_LEN) {
ret = -ENAMETOOLONG;
goto out;
}
ino = btrfs_root_ref_dirid(path.nodes[0], rr);
read_extent_buffer(path.nodes[0], path_ret,
(unsigned long)(rr + 1), name_len);
path_ret[name_len] = '/';
path_ret[name_len + 1] = '\0';
strncat(path_ret, tmp, PATH_MAX);
/* Get the path inside the parent subvolume */
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
location.objectid = key.offset;
location.type = BTRFS_ROOT_ITEM_KEY;
location.offset = (u64)-1;
root = btrfs_read_fs_root(fs_info, &location);
if (IS_ERR(root)) {
ret = PTR_ERR(root);
goto out;
}
ret = get_path_in_subvol(root, ino, path_ret);
if (ret < 0)
goto out;
cur = key.offset;
}
/* Add the leading '/' */
strncpy(tmp, path_ret, PATH_MAX);
strncpy(path_ret, "/", PATH_MAX);
strncat(path_ret, tmp, PATH_MAX);
out:
btrfs_release_path(&path);
free(tmp);
return ret;
}
static int get_subvol_name(u64 subvolid, char *name, int max_len)
{
struct btrfs_root_ref rref;