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btrfs-progs: use btrfs_link_subvolume() to replace btrfs_mksubvol()

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The function btrfs_mksubvol() is very different between btrfs-progs and
kernel, the former version is really just linking a subvolume to another
directory inode, but the kernel version is really to make a completely
new subvolume.

Instead of same-named function, introduce btrfs_link_subvolume() and use
it to replace the old btrfs_mksubvol().

This is done by:

- Introduce btrfs_link_subvolume()
  Which does extra checks before doing any modification:
  * Make sure the target inode is a directory
  * Make sure no filename conflict

  Then do the linkage:
  * Add the dir_item/dir_index into the parent inode
  * Add the forward and backward root refs into tree root

- Introduce link_image_subvolume() helper
  Currently btrfs_mksubvol() has a dedicated convert filename retry
  behavior, which is unnecessary and should be done by the convert code.

  Now move the filename retry behavior into the helper.

- Remove btrfs_mksubvol()
  Since there is only one caller utilizing btrfs_mksubvol(), and it's
  now gone, we can remove the old btrfs_mksubvol().

Signed-off-by: Qu Wenruo <wqu@suse.com>
This commit is contained in:
Qu Wenruo 2024-07-15 13:31:30 +09:30 committed by David Sterba
parent 3c555beabf
commit 9ad15a7301
6 changed files with 184 additions and 147 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
check/main.c
View File

@ -2361,7 +2361,7 @@ static int repair_inode_backrefs(struct btrfs_root *root,
struct btrfs_trans_handle *trans;
struct btrfs_key location;
ret = check_dir_conflict(root, backref->name,
ret = btrfs_check_dir_conflict(root, backref->name,
backref->namelen,
backref->dir,
backref->index);

107
common/root-tree-utils.c
View File

@ -105,3 +105,110 @@ error:
btrfs_abort_transaction(trans, ret);
return ret;
}
/*
* Link subvoume @subvol as @name under directory inode @parent_dir of
* subvolume @parent_root.
*/
int btrfs_link_subvolume(struct btrfs_trans_handle *trans,
struct btrfs_root *parent_root,
u64 parent_dir, const char *name,
int namelen, struct btrfs_root *subvol)
{
struct btrfs_root *tree_root = trans->fs_info->tree_root;
struct btrfs_path path = { 0 };
struct btrfs_key key;
struct btrfs_inode_item *ii;
u64 index;
u64 isize;
u32 imode;
int ret;
UASSERT(namelen && namelen <= BTRFS_NAME_LEN);
/* Make sure @parent_dir is a directory. */
key.objectid = parent_dir;
key.type = BTRFS_INODE_ITEM_KEY;
key.offset = 0;
ret = btrfs_search_slot(NULL, parent_root, &key, &path, 0, 0);
if (ret > 0)
ret = -ENOENT;
if (ret < 0) {
btrfs_release_path(&path);
return ret;
}
ii = btrfs_item_ptr(path.nodes[0], path.slots[0], struct btrfs_inode_item);
imode = btrfs_inode_mode(path.nodes[0], ii);
btrfs_release_path(&path);
if (!S_ISDIR(imode)) {
ret = -EUCLEAN;
error("%s: inode %llu of subvolume %llu is not a directory",
__func__, parent_dir, parent_root->root_key.objectid);
return ret;
}
ret = btrfs_find_free_dir_index(parent_root, parent_dir, &index);
if (ret < 0)
return ret;
/* Filename conflicts check. */
ret = btrfs_check_dir_conflict(parent_root, name, namelen, parent_dir,
index);
if (ret < 0)
return ret;
/*
* Now everything is fine, add the link.
* From now on, every error would lead to transaction abort.
*
* Add the dir_item/index first.
*/
ret = btrfs_insert_dir_item(trans, parent_root, name, namelen,
parent_dir, &subvol->root_key,
BTRFS_FT_DIR, index);
if (ret < 0)
goto abort;
/* Update inode size of the parent inode */
key.objectid = parent_dir;
key.type = BTRFS_INODE_ITEM_KEY;
key.offset = 0;
ret = btrfs_search_slot(trans, parent_root, &key, &path, 1, 1);
if (ret > 0)
ret = -ENOENT;
if (ret < 0) {
btrfs_release_path(&path);
goto abort;
}
ii = btrfs_item_ptr(path.nodes[0], path.slots[0],
struct btrfs_inode_item);
isize = btrfs_inode_size(path.nodes[0], ii);
isize += namelen * 2;
btrfs_set_inode_size(path.nodes[0], ii, isize);
btrfs_mark_buffer_dirty(path.nodes[0]);
btrfs_release_path(&path);
/* Add the root backref. */
ret = btrfs_add_root_ref(trans, tree_root, subvol->root_key.objectid,
BTRFS_ROOT_BACKREF_KEY,
parent_root->root_key.objectid, parent_dir,
index, name, namelen);
if (ret < 0)
goto abort;
/* Then forward ref*/
ret = btrfs_add_root_ref(trans, tree_root,
parent_root->root_key.objectid,
BTRFS_ROOT_REF_KEY, subvol->root_key.objectid,
parent_dir, index, name, namelen);
if (ret < 0)
goto abort;
/* For now, all root should have its refs == 1 already.
* So no need to update the root refs. */
UASSERT(btrfs_root_refs(&subvol->root_item) == 1);
return 0;
abort:
btrfs_abort_transaction(trans, ret);
return ret;
}

4
common/root-tree-utils.h
View File

@ -22,5 +22,9 @@
int btrfs_make_root_dir(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 objectid);
int btrfs_make_subvolume(struct btrfs_trans_handle *trans, u64 objectid);
int btrfs_link_subvolume(struct btrfs_trans_handle *trans,
struct btrfs_root *parent_root,
u64 parent_dir, const char *name,
int namelen, struct btrfs_root *subvol);
#endif

64
convert/main.c
View File

@ -1110,6 +1110,62 @@ static int convert_open_fs(const char *devname,
return -1;
}
static int link_image_subvolume(struct btrfs_root *image_root, char *name)
{
struct btrfs_fs_info *fs_info = image_root->fs_info;
struct btrfs_root *fs_root = fs_info->fs_root;
struct btrfs_trans_handle *trans;
char buf[BTRFS_NAME_LEN + 1]; /* for snprintf, null terminated. */
int ret;
/*
* 1 root backref 1 root forward ref, 1 dir item 1 dir index,
* and finally one root item.
*/
trans = btrfs_start_transaction(fs_root, 5);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
errno = -ret;
error("failed to start transaction to link subvolume: %m");
return PTR_ERR(trans);
}
ret = btrfs_link_subvolume(trans, fs_root, btrfs_root_dirid(&fs_root->root_item),
name, strlen(name), image_root);
/* No filename conflicts, all done. */
if (!ret)
goto commit;
/* Other unexpected errors. */
if (ret != -EEXIST) {
btrfs_abort_transaction(trans, ret);
return ret;
}
/* Filename conflicts detected, try different names. */
for (int i = 0; i < 1024; i++) {
int len;
len = snprintf(buf, ARRAY_SIZE(buf), "%s%d", name, i);
if (len == 0 || len > BTRFS_NAME_LEN) {
error("failed to find an alternative name for image_root");
ret = -EINVAL;
goto abort;
}
ret = btrfs_link_subvolume(trans, fs_root,
btrfs_root_dirid(&fs_root->root_item),
buf, len, image_root);
if (!ret)
break;
if (ret != -EEXIST)
goto abort;
}
commit:
ret = btrfs_commit_transaction(trans, fs_info->tree_root);
return ret;
abort:
btrfs_abort_transaction(trans, ret);
return ret;
}
static int do_convert(const char *devname, u32 convert_flags, u32 nodesize,
const char *fslabel, int progress,
struct btrfs_mkfs_features *features, u16 csum_type,
@ -1276,10 +1332,10 @@ static int do_convert(const char *devname, u32 convert_flags, u32 nodesize,
task_deinit(ctx.info);
}
image_root = btrfs_mksubvol(root, subvol_name,
CONV_IMAGE_SUBVOL_OBJECTID, true);
if (!image_root) {
error("unable to link subvolume %s", subvol_name);
ret = link_image_subvolume(image_root, subvol_name);
if (ret < 0) {
errno = -ret;
error("unable to link subvolume %s: %m", subvol_name);
goto fail;
}

8
kernel-shared/ctree.h
View File

@ -1212,8 +1212,10 @@ static inline int is_fstree(u64 rootid)
void btrfs_uuid_to_key(const u8 *uuid, u8 type, struct btrfs_key *key);
/* inode.c */
int check_dir_conflict(struct btrfs_root *root, char *name, int namelen,
u64 dir, u64 index);
int btrfs_find_free_dir_index(struct btrfs_root *root, u64 dir_ino,
u64 *ret_ino);
int btrfs_check_dir_conflict(struct btrfs_root *root, const char *name,
int namelen, u64 dir, u64 index);
int btrfs_new_inode(struct btrfs_trans_handle *trans, struct btrfs_root *root,
u64 ino, u32 mode);
int btrfs_change_inode_flags(struct btrfs_trans_handle *trans,
@ -1229,8 +1231,6 @@ int btrfs_add_orphan_item(struct btrfs_trans_handle *trans,
u64 ino);
int btrfs_mkdir(struct btrfs_trans_handle *trans, struct btrfs_root *root,
char *name, int namelen, u64 parent_ino, u64 *ino, int mode);
struct btrfs_root *btrfs_mksubvol(struct btrfs_root *root, const char *base,
u64 root_objectid, bool convert);
int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
struct btrfs_root *fs_root,
u64 dirid, u64 *objectid);

138
kernel-shared/inode.c
View File

@ -40,7 +40,7 @@
* Find a free inode index for later btrfs_add_link().
* Currently just search from the largest dir_index and +1.
*/
static int btrfs_find_free_dir_index(struct btrfs_root *root, u64 dir_ino,
int btrfs_find_free_dir_index(struct btrfs_root *root, u64 dir_ino,
u64 *ret_ino)
{
struct btrfs_path *path;
@ -93,8 +93,8 @@ out:
}
/* Check the dir_item/index conflicts before insert */
int check_dir_conflict(struct btrfs_root *root, char *name, int namelen,
u64 dir, u64 index)
int btrfs_check_dir_conflict(struct btrfs_root *root, const char *name,
int namelen, u64 dir, u64 index)
{
struct btrfs_path *path;
struct btrfs_key key;
@ -190,7 +190,7 @@ int btrfs_add_link(struct btrfs_trans_handle *trans, struct btrfs_root *root,
goto out;
}
ret = check_dir_conflict(root, name, namelen, parent_ino, ret_index);
ret = btrfs_check_dir_conflict(root, name, namelen, parent_ino, ret_index);
if (ret < 0 && !(ignore_existed && ret == -EEXIST))
goto out;
@ -582,136 +582,6 @@ out:
return ret;
}
struct btrfs_root *btrfs_mksubvol(struct btrfs_root *root,
const char *base, u64 root_objectid,
bool convert)
{
struct btrfs_trans_handle *trans;
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_root *new_root = NULL;
struct btrfs_path path = { 0 };
struct btrfs_inode_item *inode_item;
struct extent_buffer *leaf;
struct btrfs_key key;
u64 dirid = btrfs_root_dirid(&root->root_item);
u64 index = 2;
char buf[BTRFS_NAME_LEN + 1]; /* for snprintf null */
int len;
int i;
int ret;
len = strlen(base);
if (len == 0 || len > BTRFS_NAME_LEN)
return NULL;
key.objectid = dirid;
key.type = BTRFS_DIR_INDEX_KEY;
key.offset = (u64)-1;
ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
if (ret <= 0) {
error("search for DIR_INDEX dirid %llu failed: %d",
(unsigned long long)dirid, ret);
goto fail;
}
if (path.slots[0] > 0) {
path.slots[0]--;
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
if (key.objectid == dirid && key.type == BTRFS_DIR_INDEX_KEY)
index = key.offset + 1;
}
btrfs_release_path(&path);
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
errno = -ret;
error_msg(ERROR_MSG_START_TRANS, "%m");
goto fail;
}
key.objectid = dirid;
key.type = BTRFS_INODE_ITEM_KEY;
key.offset = 0;
ret = btrfs_lookup_inode(trans, root, &path, &key, 1);
if (ret) {
error("search for INODE_ITEM %llu failed: %d",
(unsigned long long)dirid, ret);
goto fail;
}
leaf = path.nodes[0];
inode_item = btrfs_item_ptr(leaf, path.slots[0],
struct btrfs_inode_item);
key.objectid = root_objectid;
key.type = BTRFS_ROOT_ITEM_KEY;
key.offset = (u64)-1;
memcpy(buf, base, len);
if (convert) {
for (i = 0; i < 1024; i++) {
ret = btrfs_insert_dir_item(trans, root, buf, len,
dirid, &key, BTRFS_FT_DIR, index);
if (ret != -EEXIST)
break;
len = snprintf(buf, ARRAY_SIZE(buf), "%s%d", base, i);
if (len < 1 || len > BTRFS_NAME_LEN) {
ret = -EINVAL;
break;
}
}
} else {
ret = btrfs_insert_dir_item(trans, root, buf, len, dirid, &key,
BTRFS_FT_DIR, index);
}
if (ret)
goto fail;
btrfs_set_inode_size(leaf, inode_item, len * 2 +
btrfs_inode_size(leaf, inode_item));
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(&path);
/* add the backref first */
ret = btrfs_add_root_ref(trans, tree_root, root_objectid,
BTRFS_ROOT_BACKREF_KEY,
root->root_key.objectid,
dirid, index, buf, len);
if (ret) {
error("unable to add root backref for %llu: %d",
root->root_key.objectid, ret);
goto fail;
}
/* now add the forward ref */
ret = btrfs_add_root_ref(trans, tree_root, root->root_key.objectid,
BTRFS_ROOT_REF_KEY, root_objectid,
dirid, index, buf, len);
if (ret) {
error("unable to add root ref for %llu: %d",
root->root_key.objectid, ret);
goto fail;
}
ret = btrfs_commit_transaction(trans, root);
if (ret) {
errno = -ret;
error_msg(ERROR_MSG_COMMIT_TRANS, "%m");
goto fail;
}
new_root = btrfs_read_fs_root(fs_info, &key);
if (IS_ERR(new_root)) {
error("unable to fs read root: %lu", PTR_ERR(new_root));
new_root = NULL;
}
fail:
return new_root;
}
/*
* Walk the tree of allocated inodes and find a hole.
*/