Quoting KATOH Yasufumi (ka...@jazz.email.ne.jp):
> Hi,
>
> I made changes.
>
> >>> On Sat, 18 Oct 2014 01:24:55 +0900
> in message "Re: [lxc-devel] [PATCH RFC] overlayfs: overlayfs.v22 or
> higher needs workdir option"
> I wrote:
>
> > > > Mostly ok, just a few cmments below. If you like I'll make the
> > > > changes as I apply, or you can send a new version.
>
> > > Thanks for your comment! I have some questions.
>
> > Sorry. I did not read your patch:
> >
> > https://lists.linuxcontainers.org/pipermail/lxc-devel/2014-October/010687.html
>
> > I will check it and resend this patch.
>
> * I assume that upperdir is "delta0". Is this right?
> * This patch can apply after applying the patch:
>
> https://lists.linuxcontainers.org/pipermail/lxc-devel/2014-October/010687.html
> * Add some comments.
>
> ---
> src/lxc/bdev.c | 88
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 82 insertions(+), 6 deletions(-)
>
> diff --git a/src/lxc/bdev.c b/src/lxc/bdev.c
> index 8a819ab..2253a1b 100644
> --- a/src/lxc/bdev.c
> +++ b/src/lxc/bdev.c
> @@ -2154,10 +2154,12 @@ static int overlayfs_detect(const char *path)
> static int overlayfs_mount(struct bdev *bdev)
> {
> char *options, *dup, *lower, *upper;
> - int len;
> + char *options_work, *work, *lastslash;
> + int lastslashidx;
> + int len, len2;
> unsigned long mntflags;
> char *mntdata;
> - int ret;
> + int ret, ret2;
>
> if (strcmp(bdev->type, "overlayfs"))
> return -22;
> @@ -2175,6 +2177,21 @@ static int overlayfs_mount(struct bdev *bdev)
> *upper = '\0';
> upper++;
>
> + // overlayfs.v22 or higher needs workdir option
> + // if upper is /var/lib/lxc/c2/delta0,
> + // then workdir is /var/lib/lxc/c2/olwork
> + lastslash = strrchr(upper, '/');
> + if (!lastslash)
> + return -22;
> + if (strlen(lastslash) < 7)
> + return -22;
I don't think you want to do this here. We don't know for
sure that upper ends in /delta0. And actually you don't need
to do it here, since you are allocating lastslashidx+7 below.
Or am i misreading?
> + lastslash++;
> + lastslashidx = lastslash - upper;
> +
> + work = alloca(lastslashidx + 7);
> + strncpy(work, upper, lastslashidx+7);
> + strcpy(work+lastslashidx, "olwork");
> +
> if (parse_mntopts(bdev->mntopts, &mntflags, &mntdata) < 0) {
> free(mntdata);
> return -22;
> @@ -2187,21 +2204,44 @@ static int overlayfs_mount(struct bdev *bdev)
> len = strlen(lower) + strlen(upper) +
> strlen("upperdir=,lowerdir=,") + strlen(mntdata) + 1;
> options = alloca(len);
> ret = snprintf(options, len, "upperdir=%s,lowerdir=%s,%s",
> upper, lower, mntdata);
> +
> + len2 = strlen(lower) + strlen(upper) + strlen(work)
> + + strlen("upperdir=,lowerdir=,workdir=") +
> strlen(mntdata) + 1;
> + options_work = alloca(len2);
> + ret2 = snprintf(options, len2,
> "upperdir=%s,lowerdir=%s,workdir=%s,%s",
> + upper, lower, work, mntdata);
> }
> else {
> len = strlen(lower) + strlen(upper) +
> strlen("upperdir=,lowerdir=") + 1;
> options = alloca(len);
> ret = snprintf(options, len, "upperdir=%s,lowerdir=%s", upper,
> lower);
> +
> + len2 = strlen(lower) + strlen(upper) + strlen(work)
> + + strlen("upperdir=,lowerdir=,workdir=") + 1;
> + options_work = alloca(len2);
> + ret2 = snprintf(options_work, len2,
> "upperdir=%s,lowerdir=%s,workdir=%s",
> + upper, lower, work);
> }
> - if (ret < 0 || ret >= len) {
> + if (ret < 0 || ret >= len || ret2 < 0 || ret2 >= len2) {
> free(mntdata);
> return -1;
> }
>
> + // mount without workdir option for overlayfs before v21
> ret = mount(lower, bdev->dest, "overlayfs", MS_MGC_VAL | mntflags,
> options);
> - if (ret < 0)
> - SYSERROR("overlayfs: error mounting %s onto %s options %s",
> + if (ret < 0) {
> + INFO("overlayfs: error mounting %s onto %s options %s. retry
> with workdir",
> lower, bdev->dest, options);
> +
> + // retry with workdir option for overlayfs v22 and higher
> + ret = mount(lower, bdev->dest, "overlayfs", MS_MGC_VAL |
> mntflags, options_work);
> + if (ret < 0)
> + SYSERROR("overlayfs: error mounting %s onto %s options
> %s",
> + lower, bdev->dest, options_work);
> + else
> + INFO("overlayfs: mounted %s onto %s options %s",
> + lower, bdev->dest, options_work);
> + }
> else
> INFO("overlayfs: mounted %s onto %s options %s",
> lower, bdev->dest, options);
> @@ -2266,6 +2306,7 @@ static int overlayfs_clonepaths(struct bdev *orig,
> struct bdev *new, const char
>
> if (strcmp(orig->type, "dir") == 0) {
> char *delta, *lastslash;
> + char *work;
> int ret, len, lastslashidx;
>
> // if we have /var/lib/lxc/c2/rootfs, then delta will be
> @@ -2291,6 +2332,25 @@ static int overlayfs_clonepaths(struct bdev *orig,
> struct bdev *new, const char
> if (am_unpriv() && chown_mapped_root(delta, conf) < 0)
> WARN("Failed to update ownership of %s", delta);
>
> + // make workdir for overlayfs.v22 or higher
> + // workdir is /var/lib/lxc/c2/olwork
> + // it is used to prepare files before atomically swithing with
> destination,
> + // and needs to be on the same filesystem as upperdir,
> + // so it's OK for it to be empty.
> + work = malloc(lastslashidx + 7);
> + if (!work)
> + return -1;
> + strncpy(work, new->dest, lastslashidx+1);
> + strcpy(work+lastslashidx, "olwork");
> + if ((ret = mkdir(work, 0755)) < 0) {
> + SYSERROR("error: mkdir %s", work);
> + free(work);
> + return -1;
> + }
> + if (am_unpriv() && chown_mapped_root(work, conf) < 0)
> + WARN("Failed to update ownership of %s", work);
> + free(work);
> +
> // the src will be 'overlayfs:lowerdir:upperdir'
> len = strlen(delta) + strlen(orig->src) + 12;
> new->src = malloc(len);
> @@ -2307,7 +2367,7 @@ static int overlayfs_clonepaths(struct bdev *orig,
> struct bdev *new, const char
> // I think we want to use the original lowerdir, with a
> // private delta which is originally rsynced from the
> // original delta
> - char *osrc, *odelta, *nsrc, *ndelta;
> + char *osrc, *odelta, *nsrc, *ndelta, *work;
> int len, ret;
> if (!(osrc = strdup(orig->src)))
> return -22;
> @@ -2331,6 +2391,22 @@ static int overlayfs_clonepaths(struct bdev *orig,
> struct bdev *new, const char
> }
> if (am_unpriv() && chown_mapped_root(ndelta, conf) < 0)
> WARN("Failed to update ownership of %s", ndelta);
> +
> + // make workdir for overlayfs.v22 or higher
> + // for details, see above.
> + work = strdup(ndelta);
> + if (!work)
> + return -1;
> + strcpy(&work[strlen(work)-6], "olwork");
We can't be certain here that ndelta ends in 'delta0'. It ends in whatever
odelta ended in. So you need to do the strrchr('/') on ndelta and allocate
7 chars more than that.
> + if (mkdir(work, 0755) < 0) {
> + SYSERROR("error: mkdir %s", work);
> + free(work);
> + return -1;
> + }
> + if (am_unpriv() && chown_mapped_root(ndelta, conf) < 0)
You're calling chown_mapped_root on ndelta, not on work
> + WARN("Failed to update ownership of %s", work);
> + free(work);
> +
> struct rsync_data_char rdata;
> rdata.src = odelta;
> rdata.dest = ndelta;
> --
> 2.1.1
>
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