[lxc-devel] [PATCH v5] Make overlayfs mounts work directly
Christian Brauner
christianvanbrauner at gmail.com
Thu Oct 8 17:31:16 UTC 2015
Yup. I think I have an idea for the do_lxcapi_clone() changes (using
lxc_list_for_each()). Unless you have a smarter approach already.
On Oct 8, 2015 4:59 PM, "Serge Hallyn" <serge.hallyn at ubuntu.com> wrote:
>
> Yes, I think so. Worse, I think that'll mean we'll have to also restore
> those at snapshot restore.
>
> Quoting Christian Brauner (christianvanbrauner at gmail.com):
> > Fair enough. Should we then adapt do_lxcapi_clone() to replace any
mountentries
> > that involve references to the original container with the name of the
new
> > container or should we just have users do it manually? (Because
currently the
> > presence of any lxc.mount.entry = ... overlay ... will prevent clones
from
> > working out of the box... Maybe I'm just being pedantic here...)
> >
> > On Wed, Oct 07, 2015 at 01:20:35PM +0000, Serge Hallyn wrote:
> > > mount targets when relative are relative to the mounted rootfs dir
> > > (with absolute paths under the *not-mounted* rootfs dir being auto-
> > > translated to being under the mounted rootfs dir).
> > >
> > > These paths would be relative to the containerdir. I think that's too
> > > confusing.
> > >
> > > Quoting Christian Brauner (christianvanbrauner at gmail.com):
> > > > I now wonder if it wouldn't be smarter to force users to specify
relative paths
> > > > for upper and workdir
> > > >
> > > > lxc.mount.entry = /lower merged overlay
lowerdir=/lower,upper=upper,workdir=workdir,create=dir
> > > >
> > > > and fill in the missing path in mount_entry_create_*_dirs().
Otherwise these
> > > > mounts won't work out of the box when a clone of the container is
made and
> > > > started... Thoughts?
> > > >
> > > > On Tue, Oct 06, 2015 at 08:38:13PM +0200, Christian Brauner wrote:
> > > > > When users wanted to mount overlay directories with
lxc.mount.entry they had to
> > > > > create upperdirs and workdirs beforehand in order to mount them.
To create it
> > > > > for them we add the functions mount_entry_create_overlay_dirs()
and
> > > > > mount_entry_create_aufs_dirs() which do this for them. User can
now simply
> > > > > specify e.g.:
> > > > >
> > > > > lxc.mount.entry = /lower merged overlay
lowerdir=/lower,upper=/upper,workdir=/workdir,create=dir
> > > > >
> > > > > and /upper and /workdir will be created for them. /upper and
/workdir need to
> > > > > be absolute paths to directories which are created under the
containerdir (e.g.
> > > > > under $lxcpath/CONTAINERNAME/). Relative mountpoints, mountpoints
outside the
> > > > > containerdir, and mountpoints within the container's rootfs are
ignored. (The
> > > > > latter *might* change in the future should it be considered
safe/useful.)
> > > > >
> > > > > Specifying
> > > > >
> > > > > lxc.mount.entry = /lower merged overlay
lowerdir=/lower:/lower2,create=dir
> > > > >
> > > > > will lead to a read-only overlay mount in accordance with the
> > > > > kernel-documentation.
> > > > >
> > > > > Specifying
> > > > >
> > > > > lxc.mount.entry = /lower merged overlay
lowerdir=/lower,create=dir
> > > > >
> > > > > will fail when no upperdir and workdir options are given.
> > > > >
> > > > > Signed-off-by: Christian Brauner <christianvanbrauner at gmail.com>
> > > > > Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>
> > > > > ---
> > > > > src/lxc/conf.c | 162
++++++++++++++++++++++++++++++++++++++++++++++++++++-----
> > > > > 1 file changed, 150 insertions(+), 12 deletions(-)
> > > > >
> > > > > diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> > > > > index 6728c78..5a3209a 100644
> > > > > --- a/src/lxc/conf.c
> > > > > +++ b/src/lxc/conf.c
> > > > > @@ -1815,13 +1815,151 @@ static void cull_mntent_opt(struct
mntent *mntent)
> > > > > }
> > > > > }
> > > > >
> > > > > +static int mount_entry_create_overlay_dirs(const struct mntent
*mntent,
> > > > > + const struct
lxc_rootfs *rootfs)
> > > > > +{
> > > > > + char *del = NULL;
> > > > > + char *lxcpath = NULL;
> > > > > + char *upperdir = NULL;
> > > > > + char *workdir = NULL;
> > > > > + char **opts = NULL;
> > > > > + size_t arrlen = 0;
> > > > > + size_t dirlen = 0;
> > > > > + size_t i;
> > > > > + size_t len = 0;
> > > > > + size_t rootfslen = 0;
> > > > > +
> > > > > + if (!rootfs->path)
> > > > > + return -1;
> > > > > +
> > > > > + opts = lxc_string_split(mntent->mnt_opts, ',');
> > > > > + if (opts)
> > > > > + arrlen = lxc_array_len((void **)opts);
> > > > > + else
> > > > > + return -1;
> > > > > +
> > > > > + for (i = 0; i < arrlen; i++) {
> > > > > + if (strstr(opts[i], "upperdir=") &&
(strlen(opts[i]) > (len = strlen("upperdir="))))
> > > > > + upperdir = opts[i] + len;
> > > > > + else if (strstr(opts[i], "workdir=") &&
(strlen(opts[i]) > (len = strlen("workdir="))))
> > > > > + workdir = opts[i] + len;
> > > > > + }
> > > > > +
> > > > > + lxcpath = strdup(rootfs->path);
> > > > > + if (!lxcpath) {
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return -1;
> > > > > + }
> > > > > +
> > > > > + del = strstr(lxcpath, "/rootfs");
> > > > > + if (!del) {
> > > > > + free(lxcpath);
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return -1;
> > > > > + }
> > > > > + *del = '\0';
> > > > > +
> > > > > + dirlen = strlen(lxcpath);
> > > > > + rootfslen = strlen(rootfs->path);
> > > > > +
> > > > > + /* We neither allow users to create upperdirs and
workdirs outside the
> > > > > + * containerdir nor inside the rootfs. The latter might
be debatable. */
> > > > > + if (upperdir)
> > > > > + if ((strncmp(upperdir, lxcpath, dirlen) == 0) &&
(strncmp(upperdir, rootfs->path, rootfslen) != 0))
> > > > > + if (mkdir_p(upperdir, 0755) < 0) {
> > > > > + WARN("Failed to create upperdir");
> > > > > + }
> > > > > +
> > > > > +
> > > > > + if (workdir)
> > > > > + if ((strncmp(workdir, lxcpath, dirlen) == 0) &&
(strncmp(workdir, rootfs->path, rootfslen) != 0))
> > > > > + if (mkdir_p(workdir, 0755) < 0) {
> > > > > + WARN("Failed to create workdir");
> > > > > + }
> > > > > +
> > > > > + free(lxcpath);
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return 0;
> > > > > +}
> > > > > +
> > > > > +static int mount_entry_create_aufs_dirs(const struct mntent
*mntent,
> > > > > + const struct lxc_rootfs
*rootfs)
> > > > > +{
> > > > > + char *del = NULL;
> > > > > + char *lxcpath = NULL;
> > > > > + char *scratch = NULL;
> > > > > + char *tmp = NULL;
> > > > > + char *upperdir = NULL;
> > > > > + char **opts = NULL;
> > > > > + size_t arrlen = 0;
> > > > > + size_t i;
> > > > > + size_t len = 0;
> > > > > +
> > > > > + if (!rootfs->path)
> > > > > + return -1;
> > > > > +
> > > > > + opts = lxc_string_split(mntent->mnt_opts, ',');
> > > > > + if (opts)
> > > > > + arrlen = lxc_array_len((void **)opts);
> > > > > + else
> > > > > + return -1;
> > > > > +
> > > > > + for (i = 0; i < arrlen; i++) {
> > > > > + if (strstr(opts[i], "br=") && (strlen(opts[i]) >
(len = strlen("br="))))
> > > > > + tmp = opts[i] + len;
> > > > > + }
> > > > > + if (!tmp) {
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return -1;
> > > > > + }
> > > > > +
> > > > > + upperdir = strtok_r(tmp, ":=", &scratch);
> > > > > + if (!upperdir) {
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return -1;
> > > > > + }
> > > > > +
> > > > > + lxcpath = strdup(rootfs->path);
> > > > > + if (!lxcpath) {
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return -1;
> > > > > + }
> > > > > +
> > > > > + del = strstr(lxcpath, "/rootfs");
> > > > > + if (!del) {
> > > > > + free(lxcpath);
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return -1;
> > > > > + }
> > > > > + *del = '\0';
> > > > > +
> > > > > + /* We neither allow users to create upperdirs outside the
containerdir
> > > > > + * nor inside the rootfs. The latter might be debatable.
*/
> > > > > + if ((strncmp(upperdir, lxcpath, strlen(lxcpath)) == 0) &&
(strncmp(upperdir, rootfs->path, strlen(rootfs->path)) != 0))
> > > > > + if (mkdir_p(upperdir, 0755) < 0) {
> > > > > + WARN("Failed to create upperdir");
> > > > > + }
> > > > > +
> > > > > + free(lxcpath);
> > > > > + lxc_free_array((void **)opts, free);
> > > > > + return 0;
> > > > > +}
> > > > > +
> > > > > static int mount_entry_create_dir_file(const struct mntent
*mntent,
> > > > > - const char* path)
> > > > > + const char* path, const
struct lxc_rootfs *rootfs)
> > > > > {
> > > > > char *pathdirname = NULL;
> > > > > int ret = 0;
> > > > > FILE *pathfile = NULL;
> > > > >
> > > > > + if (strncmp(mntent->mnt_type, "overlay", 7) == 0) {
> > > > > + if (mount_entry_create_overlay_dirs(mntent,
rootfs) < 0)
> > > > > + return -1;
> > > > > + } else if (strncmp(mntent->mnt_type, "aufs", 4) == 0) {
> > > > > + if (mount_entry_create_aufs_dirs(mntent, rootfs)
< 0)
> > > > > + return -1;
> > > > > + }
> > > > > +
> > > > > if (hasmntopt(mntent, "create=dir")) {
> > > > > if (mkdir_p(path, 0755) < 0) {
> > > > > WARN("Failed to create mount target
'%s'", path);
> > > > > @@ -1839,23 +1977,23 @@ static int
mount_entry_create_dir_file(const struct mntent *mntent,
> > > > > if (!pathfile) {
> > > > > WARN("Failed to create mount target
'%s'", path);
> > > > > ret = -1;
> > > > > - }
> > > > > - else
> > > > > + } else {
> > > > > fclose(pathfile);
> > > > > + }
> > > > > }
> > > > > free(pathdirname);
> > > > > return ret;
> > > > > }
> > > > >
> > > > > static inline int mount_entry_on_generic(struct mntent *mntent,
> > > > > - const char* path, const char *rootfs)
> > > > > + const char* path, const struct lxc_rootfs
*rootfs)
> > > > > {
> > > > > unsigned long mntflags;
> > > > > char *mntdata;
> > > > > int ret;
> > > > > bool optional = hasmntopt(mntent, "optional") != NULL;
> > > > >
> > > > > - ret = mount_entry_create_dir_file(mntent, path);
> > > > > + ret = mount_entry_create_dir_file(mntent, path, rootfs);
> > > > >
> > > > > if (ret < 0)
> > > > > return optional ? 0 : -1;
> > > > > @@ -1867,11 +2005,11 @@ static inline int
mount_entry_on_generic(struct mntent *mntent,
> > > > > return -1;
> > > > > }
> > > > >
> > > > > - ret = mount_entry(mntent->mnt_fsname, path,
mntent->mnt_type,
> > > > > - mntflags, mntdata, optional, rootfs);
> > > > > + ret = mount_entry(mntent->mnt_fsname, path,
mntent->mnt_type, mntflags,
> > > > > + mntdata, optional,
> > > > > + rootfs->path ? rootfs->mount : NULL);
> > > > >
> > > > > free(mntdata);
> > > > > -
> > > > > return ret;
> > > > > }
> > > > >
> > > > > @@ -1924,17 +2062,17 @@ skipabs:
> > > > > return -1;
> > > > > }
> > > > >
> > > > > - return mount_entry_on_generic(mntent, path,
rootfs->mount);
> > > > > + return mount_entry_on_generic(mntent, path, rootfs);
> > > > > }
> > > > >
> > > > > static int mount_entry_on_relative_rootfs(struct mntent *mntent,
> > > > > - const char *rootfs)
> > > > > + const struct lxc_rootfs
*rootfs)
> > > > > {
> > > > > char path[MAXPATHLEN];
> > > > > int ret;
> > > > >
> > > > > /* relative to root mount point */
> > > > > - ret = snprintf(path, sizeof(path), "%s/%s", rootfs,
mntent->mnt_dir);
> > > > > + ret = snprintf(path, sizeof(path), "%s/%s",
rootfs->mount, mntent->mnt_dir);
> > > > > if (ret >= sizeof(path)) {
> > > > > ERROR("path name too long");
> > > > > return -1;
> > > > > @@ -1961,7 +2099,7 @@ static int mount_file_entries(const struct
lxc_rootfs *rootfs, FILE *file,
> > > > > /* We have a separate root, mounts are relative
to it */
> > > > > if (mntent.mnt_dir[0] != '/') {
> > > > > if
(mount_entry_on_relative_rootfs(&mntent,
> > > > > -
rootfs->mount))
> > > > > +
rootfs))
> > > > > goto out;
> > > > > continue;
> > > > > }
> > > > > --
> > > > > 2.6.1
> > > > >
> > >
> > >
> > >
> > > > _______________________________________________
> > > > lxc-devel mailing list
> > > > lxc-devel at lists.linuxcontainers.org
> > > > http://lists.linuxcontainers.org/listinfo/lxc-devel
> > >
> > > _______________________________________________
> > > lxc-devel mailing list
> > > lxc-devel at lists.linuxcontainers.org
> > > http://lists.linuxcontainers.org/listinfo/lxc-devel
>
>
>
> > _______________________________________________
> > lxc-devel mailing list
> > lxc-devel at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-devel
>
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linuxcontainers.org/pipermail/lxc-devel/attachments/20151008/42bea5ec/attachment-0001.html>
More information about the lxc-devel
mailing list