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-rw-r--r--man/tmpfiles.d.xml16
-rw-r--r--src/basic/btrfs-util.c18
-rw-r--r--src/basic/btrfs-util.h4
-rw-r--r--src/tmpfiles/tmpfiles.c24
4 files changed, 49 insertions, 13 deletions
diff --git a/man/tmpfiles.d.xml b/man/tmpfiles.d.xml
index 3f6128cb5b..5bf1f2956b 100644
--- a/man/tmpfiles.d.xml
+++ b/man/tmpfiles.d.xml
@@ -169,13 +169,15 @@
<varlistentry>
<term><varname>v</varname></term>
<listitem><para>Create a subvolume if the path does not
- exist yet and the file system supports this
- (btrfs). Otherwise, create a normal directory, in the same
- way as <varname>d</varname>. A subvolume created with this
- line type is not assigned to any higher-level quota
- group. For that, use <varname>q</varname> or
- <varname>Q</varname>, which allow creating simple quota group
- hierarchies, see below.</para></listitem>
+ exist yet, the file system supports subvolumes (btrfs), and
+ the system itself is installed into a subvolume
+ (specifically: the root directory <filename>/</filename> is
+ itself a subvolume). Otherwise, create a normal directory, in
+ the same way as <varname>d</varname>. A subvolume created
+ with this line type is not assigned to any higher-level
+ quota group. For that, use <varname>q</varname> or
+ <varname>Q</varname>, which allow creating simple quota
+ group hierarchies, see below.</para></listitem>
</varlistentry>
<varlistentry>
diff --git a/src/basic/btrfs-util.c b/src/basic/btrfs-util.c
index 290fabdeff..8c90e1e4a2 100644
--- a/src/basic/btrfs-util.c
+++ b/src/basic/btrfs-util.c
@@ -105,7 +105,7 @@ int btrfs_is_filesystem(int fd) {
return F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC);
}
-int btrfs_is_subvol(int fd) {
+int btrfs_is_subvol_fd(int fd) {
struct stat st;
assert(fd >= 0);
@@ -121,6 +121,18 @@ int btrfs_is_subvol(int fd) {
return btrfs_is_filesystem(fd);
}
+int btrfs_is_subvol(const char *path) {
+ _cleanup_close_ int fd = -1;
+
+ assert(path);
+
+ fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC|O_DIRECTORY);
+ if (fd < 0)
+ return -errno;
+
+ return btrfs_is_subvol_fd(fd);
+}
+
int btrfs_subvol_make(const char *path) {
struct btrfs_ioctl_vol_args args = {};
_cleanup_close_ int fd = -1;
@@ -1682,7 +1694,7 @@ int btrfs_subvol_snapshot_fd(int old_fd, const char *new_path, BtrfsSnapshotFlag
assert(old_fd >= 0);
assert(new_path);
- r = btrfs_is_subvol(old_fd);
+ r = btrfs_is_subvol_fd(old_fd);
if (r < 0)
return r;
if (r == 0) {
@@ -1868,7 +1880,7 @@ int btrfs_subvol_auto_qgroup_fd(int fd, uint64_t subvol_id, bool insert_intermed
*/
if (subvol_id == 0) {
- r = btrfs_is_subvol(fd);
+ r = btrfs_is_subvol_fd(fd);
if (r < 0)
return r;
if (!r)
diff --git a/src/basic/btrfs-util.h b/src/basic/btrfs-util.h
index fc9efd72d5..8c11ce35d2 100644
--- a/src/basic/btrfs-util.h
+++ b/src/basic/btrfs-util.h
@@ -56,7 +56,9 @@ typedef enum BtrfsRemoveFlags {
} BtrfsRemoveFlags;
int btrfs_is_filesystem(int fd);
-int btrfs_is_subvol(int fd);
+
+int btrfs_is_subvol_fd(int fd);
+int btrfs_is_subvol(const char *path);
int btrfs_reflink(int infd, int outfd);
int btrfs_clone_range(int infd, uint64_t in_offset, int ofd, uint64_t out_offset, uint64_t sz);
diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index 74b6b91593..f9a759e223 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -1226,8 +1226,28 @@ static int create_item(Item *i) {
mkdir_parents_label(i->path, 0755);
if (IN_SET(i->type, CREATE_SUBVOLUME, CREATE_SUBVOLUME_INHERIT_QUOTA, CREATE_SUBVOLUME_NEW_QUOTA)) {
- RUN_WITH_UMASK((~i->mode) & 0777)
- r = btrfs_subvol_make(i->path);
+
+ if (btrfs_is_subvol(isempty(arg_root) ? "/" : arg_root) <= 0)
+
+ /* Don't create a subvolume unless the
+ * root directory is one, too. We do
+ * this under the assumption that if
+ * the root directory is just a plain
+ * directory (i.e. very light-weight),
+ * we shouldn't try to split it up
+ * into subvolumes (i.e. more
+ * heavy-weight). Thus, chroot()
+ * environments and suchlike will get
+ * a full brtfs subvolume set up below
+ * their tree only if they
+ * specifically set up a btrfs
+ * subvolume for the root dir too. */
+
+ r = -ENOTTY;
+ else {
+ RUN_WITH_UMASK((~i->mode) & 0777)
+ r = btrfs_subvol_make(i->path);
+ }
} else
r = 0;