Stas,
please see my comment below.
On 28.09.2015 16:16, Stanislav Kinsburskiy wrote:
> From: Stanislav Kinsburskiy <[email protected]>
>
> There could be a unix socket (thanks to supervisord), which was unlinked, but
> also a hardlink to it was created prior to unlink.
> This basically means, that unlinked socket and it's hardlink points to the
> same inode.
> In such a case we can't just recreate unlinked socket in /tmp directory, like
> we did before. Becuase it this case connect to linked dentry will fail becuase
> of different inode.
> We have to try to find another dentry, poiting to this inode and dump it's
> path, which will be used to recreate unlinked socket on restore.
> We need also to dump dentry mount, so we can lookup it on restore. BTW, in
> this case socket will be restored via unix_bind_to_mntref() instead of
> unix_bind_to_path().
>
> Signed-off-by: Stanislav Kinsburskiy <[email protected]>
> ---
> include/linux/cpt_image.h | 5 ++++
> kernel/cpt/cpt_socket.c | 52
> +++++++++++++++++++++++++++++++--------------
> 2 files changed, 41 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/cpt_image.h b/include/linux/cpt_image.h
> index 30a625d..75fa878 100644
> --- a/include/linux/cpt_image.h
> +++ b/include/linux/cpt_image.h
> @@ -963,6 +963,11 @@ struct cpt_sock_image
>
> __u32 cpt_i_uid;
> __u32 cpt_i_gid;
> +
> + __u32 cpt_d_alias[128/4];
> +
> + __u32 cpt_d_aliaslen;
> + __u32 __cpt_pad15;
> } __attribute__ ((aligned (8)));
size of this structure increases ==> CPT image version should be increased ==>
it's impossible to migrate from new kernels to old ones.
Am I missed something?
> struct cpt_sockmc_image {
> diff --git a/kernel/cpt/cpt_socket.c b/kernel/cpt/cpt_socket.c
> index 863aefe..88b4bd7 100644
> --- a/kernel/cpt/cpt_socket.c
> +++ b/kernel/cpt/cpt_socket.c
> @@ -543,28 +543,47 @@ static int cpt_dump_unix_socket(struct sock *sk, struct
> cpt_sock_image *v, cpt_c
>
> if (unix_sk(sk)->dentry) {
> struct dentry *d = unix_sk(sk)->dentry;
> + unsigned long pg = __get_free_page(GFP_KERNEL);
> + struct path p;
> + char *path, *cpt_path;
> + int err = 0;
> + __u32 *path_len;
> +
> + if (!pg)
> + return -ENOMEM;
> +
> v->cpt_i_uid = d->d_inode->i_uid;
> v->cpt_i_gid = d->d_inode->i_gid;
>
> if (IS_ROOT(d) || !d_unhashed(d)) {
> - int err = 0;
> - struct path p = {unix_sk(sk)->mnt, d};
> - char *path;
> - unsigned long pg = __get_free_page(GFP_KERNEL);
> + p.dentry = dget(d);
> + cpt_path = ((char*)v->cpt_laddr) + 2;
> + path_len = &v->cpt_laddrlen;
> + } else {
> + v->cpt_sockflags |= CPT_SOCK_DELETED;
> + v->cpt_d_aliaslen = 0;
> + p.dentry = NULL;
>
> - if (!pg)
> - return -ENOMEM;
> + if (d->d_inode->i_nlink != 0) {
> + p.dentry = get_linked_dentry(d,
> unix_sk(sk)->mnt, ctx);
> + cpt_path = (char *)v->cpt_d_alias;
> + path_len = &v->cpt_d_aliaslen;
> + }
> + }
> +
> + if (!IS_ERR_OR_NULL(p.dentry)) {
> + p.mnt = unix_sk(sk)->mnt;
>
> path = d_path(&p, (char *)pg, PAGE_SIZE);
>
> if (!IS_ERR(path)) {
> int len = strlen(path);
> if (len < 126) {
> - strcpy(((char*)v->cpt_laddr)+2, path);
> - v->cpt_laddrlen = len + 2;
> - } else {
> - wprintk_ctx("af_unix path is too long:
> %s (%s)\n", path, ((char*)v->cpt_laddr)+2);
> - }
> + strcpy(cpt_path, path);
> + *path_len = len + 2;
> + } else
> + wprintk_ctx("af_unix path is too long:
> %s (%s)\n", path, cpt_path);
> +
> if (cpt_need_delayfs(unix_sk(sk)->mnt))
> v->cpt_sockflags |= CPT_SOCK_DELAYED;
>
> @@ -575,11 +594,12 @@ static int cpt_dump_unix_socket(struct sock *sk, struct
> cpt_sock_image *v, cpt_c
> eprintk_ctx("cannot get path of an af_unix
> socket\n");
> err = PTR_ERR(path);
> }
> - free_page(pg);
> - if (err)
> - return err;
> - } else
> - v->cpt_sockflags |= CPT_SOCK_DELETED;
> + dput(p.dentry);
> + }
> +
> + free_page(pg);
> + if (err)
> + return err;
> }
>
> /* If the socket is connected, find its peer. If peer is not
>
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