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btrfs: use unpriv subvol info ioctl (#38230)

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Let's stop doing privileged low-level ioctls, if we also can get
unprivileged high-level ioctls for the same.
This commit is contained in:
Yu Watanabe
2025-07-16 05:24:28 +09:00
committed by GitHub
parent cf71be0a9e 4b27025223
commit 319fe95fa3
3 changed files with 22 additions and 74 deletions
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91
src/shared/btrfs-util.c
View File

@@ -299,23 +299,6 @@ static int btrfs_iterate(BtrfsForeachIterator *i) {
btrfs_iterate(&iterator) > 0; )
int btrfs_subvol_get_info_fd(int fd, uint64_t subvol_id, BtrfsSubvolInfo *ret) {
struct btrfs_ioctl_search_args args = {
/* Tree of tree roots */
.key.tree_id = BTRFS_ROOT_TREE_OBJECTID,
/* Look precisely for the subvolume items */
.key.min_type = BTRFS_ROOT_ITEM_KEY,
.key.max_type = BTRFS_ROOT_ITEM_KEY,
.key.min_offset = 0,
.key.max_offset = UINT64_MAX,
/* No restrictions on the other components */
.key.min_transid = 0,
.key.max_transid = UINT64_MAX,
};
bool found = false;
int r;
assert(fd >= 0);
@@ -327,66 +310,30 @@ int btrfs_subvol_get_info_fd(int fd, uint64_t subvol_id, BtrfsSubvolInfo *ret) {
if (fd < 0)
return fd;
if (subvol_id == 0) {
r = btrfs_subvol_get_id_fd(fd, &subvol_id);
if (r < 0)
return r;
} else {
r = fd_is_fs_type(fd, BTRFS_SUPER_MAGIC);
if (r < 0)
return r;
if (r == 0)
return -ENOTTY;
}
r = fd_is_fs_type(fd, BTRFS_SUPER_MAGIC);
if (r < 0)
return r;
if (r == 0)
return -ENOTTY;
args.key.min_objectid = args.key.max_objectid = subvol_id;
struct btrfs_ioctl_get_subvol_info_args info;
if (ioctl(fd, BTRFS_IOC_GET_SUBVOL_INFO, &info) < 0)
return -errno;
while (btrfs_ioctl_search_args_compare(&args) <= 0) {
struct btrfs_ioctl_search_header sh;
const void *body;
*ret = (BtrfsSubvolInfo) {
.subvol_id = info.treeid,
.otime = info.otime.sec * USEC_PER_SEC + (info.otime.nsec / NSEC_PER_USEC),
.ctime = info.ctime.sec * USEC_PER_SEC + (info.ctime.nsec / NSEC_PER_USEC),
.read_only = FLAGS_SET(info.flags, BTRFS_SUBVOL_RDONLY),
};
args.key.nr_items = 256;
if (ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args) < 0)
return -errno;
assert_cc(sizeof(info.uuid) == sizeof(sd_id128_t));
memcpy(&ret->uuid, info.uuid, sizeof(sd_id128_t));
if (args.key.nr_items <= 0)
break;
assert_cc(sizeof(info.parent_uuid) == sizeof(sd_id128_t));
memcpy(&ret->parent_uuid, info.parent_uuid, sizeof(sd_id128_t));
FOREACH_BTRFS_IOCTL_SEARCH_HEADER(sh, body, args) {
/* Make sure we start the next search at least from this entry */
btrfs_ioctl_search_args_set(&args, &sh);
if (sh.objectid != subvol_id)
continue;
if (sh.type != BTRFS_ROOT_ITEM_KEY)
continue;
/* Older versions of the struct lacked the otime setting */
if (sh.len < offsetof(struct btrfs_root_item, otime) + sizeof(struct btrfs_timespec))
continue;
const struct btrfs_root_item *ri = body;
ret->otime = (usec_t) le64toh(ri->otime.sec) * USEC_PER_SEC +
(usec_t) le32toh(ri->otime.nsec) / NSEC_PER_USEC;
ret->subvol_id = subvol_id;
ret->read_only = le64toh(ri->flags) & BTRFS_ROOT_SUBVOL_RDONLY;
assert_cc(sizeof(ri->uuid) == sizeof(ret->uuid));
memcpy(&ret->uuid, ri->uuid, sizeof(ret->uuid));
memcpy(&ret->parent_uuid, ri->parent_uuid, sizeof(ret->parent_uuid));
found = true;
goto finish;
}
/* Increase search key by one, to read the next item, if we can. */
if (!btrfs_ioctl_search_args_inc(&args))
break;
}
finish:
return found ? 0 : -ENODATA;
return 0;
}
int btrfs_qgroup_get_quota_fd(int fd, uint64_t qgroupid, BtrfsQuotaInfo *ret) {

3
src/shared/btrfs-util.h
View File

@@ -8,7 +8,8 @@
typedef struct BtrfsSubvolInfo {
uint64_t subvol_id;
usec_t otime;
usec_t otime; /* creation time */
usec_t ctime; /* change time */
sd_id128_t uuid;
sd_id128_t parent_uuid;

2
src/shared/discover-image.c
View File

@@ -430,7 +430,7 @@ static int image_make(
filename,
info.read_only || read_only,
info.otime,
0,
info.ctime,
ret);
if (r < 0)
return r;