summaryrefslogtreecommitdiff
path: root/src
diff options
context:
space:
mode:
authorLennart Poettering <lennart@poettering.net>2015-11-16 15:25:42 +0100
committerLennart Poettering <lennart@poettering.net>2015-11-16 15:25:42 +0100
commit2904e949f23aeb17b7e21a2a0f8c43f959a07f98 (patch)
tree741b948bb870113c5bdd21783cc3948555b609d7 /src
parentab32771aa0c2c2ab70248e7e0a4be92fd73512ad (diff)
tmpfiles: create subvolumes for "v", "q", and "Q" only if / is a subvolume
It's not a good idea to create subvolumes for parts of the OS tree (such as /home, or /var) if the root directory is not a subvolume too. We shouldn't assume control of "heavier" objects such as subvolumes, if the originating object (the root directory) is a "light-weight" object, i.e. a plain directory. Effectively this means that chroot() environments that are run on a plain directory do not have to deal with problems around systemd creating subvolumes that cannot be removed with a simple "rm" anymore. However, if the chroot manager creates a proper subvolume for such an environment it will also get further subvolumes placed in there, under the assumption that the manager understands the concept of subvolumes in that case.
Diffstat (limited to 'src')
-rw-r--r--src/basic/btrfs-util.c18
-rw-r--r--src/basic/btrfs-util.h4
-rw-r--r--src/tmpfiles/tmpfiles.c24
3 files changed, 40 insertions, 6 deletions
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;