We don't support multiple devpts mounts in a container. So
bail on checkpoint if a container has them. This will cause
checkpoint to fail of a container which still has a pty from
parent container in use.
Note one issue with this is the register_checkpoint_obj(&&ckpt_obj_ptsns_ops)
done from module_init(). We either need to add a matching unregister,
or maybe move this into drivers/char/tty_io.c.
Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
drivers/char/tty_io.c | 27 +++++++++++++++++++++++++++
fs/devpts/inode.c | 9 ++++++++-
include/linux/checkpoint_hdr.h | 2 ++
include/linux/checkpoint_types.h | 2 ++
include/linux/devpts_fs.h | 22 ++++++++++++++++++++--
5 files changed, 59 insertions(+), 3 deletions(-)
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index d264000..d24752e 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -96,6 +96,7 @@
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/seq_file.h>
+#include <linux/mount.h>
#include <linux/uaccess.h>
#include <asm/system.h>
@@ -2687,6 +2688,27 @@ static int tty_can_checkpoint(struct ckpt_ctx *ctx, struct tty_struct *tty)
return 1;
}
+/*
+ * If tty_file_checkpoint() ever supports more than unix98 ptys we'll have
+ * to check for that
+ */
+static int detect_multiple_ptsns(struct ckpt_ctx *ctx, struct file *file)
+{
+ int objref;
+ int new;
+
+ objref = ckpt_obj_lookup_add(ctx, file->f_path.mnt->mnt_sb,
+ CKPT_OBJ_PTS_NS, &new);
+ if (objref < 0)
+ return objref;
+ if (new && ctx->num_devpts_ns)
+ return -EBUSY;
+ if (file->f_path.mnt->mnt_ns != ctx->root_nsproxy->mnt_ns)
+ return -EBUSY;
+ ctx->num_devpts_ns++;
+ return 0;
+}
+
static int tty_file_checkpoint(struct ckpt_ctx *ctx, struct file *file)
{
struct ckpt_hdr_file_tty *h;
@@ -2732,6 +2754,11 @@ static int tty_file_checkpoint(struct ckpt_ctx *ctx, struct file *file)
ret = ckpt_write_obj(ctx, &h->common.h);
ckpt_hdr_put(ctx, h);
+
+ ret = detect_multiple_ptsns(ctx, file);
+ if (ret)
+ ckpt_err(ctx, ret, "Open pty from alien ptsns\n");
+
return ret;
}
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 75fb8c5..83f42b9 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -572,7 +572,14 @@ out:
static int __init init_devpts_fs(void)
{
- int err = register_filesystem(&devpts_fs_type);
+ int err;
+#ifdef CONFIG_CHECKPOINT
+ err = register_checkpoint_obj(&ckpt_obj_ptsns_ops);
+ if (err)
+ return err;
+#endif
+
+ err = register_filesystem(&devpts_fs_type);
if (!err) {
devpts_mnt = kern_mount(&devpts_fs_type);
if (IS_ERR(devpts_mnt)) {
diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
index eb5e1b4..694fdfe 100644
--- a/include/linux/checkpoint_hdr.h
+++ b/include/linux/checkpoint_hdr.h
@@ -271,6 +271,8 @@ enum obj_type {
#define CKPT_OBJ_NET_NS CKPT_OBJ_NET_NS
CKPT_OBJ_NETDEV,
#define CKPT_OBJ_NETDEV CKPT_OBJ_NETDEV
+ CKPT_OBJ_PTS_NS,
+#define CKPT_OBJ_PTS_NS CKPT_OBJ_PTS_NS
CKPT_OBJ_MAX
#define CKPT_OBJ_MAX CKPT_OBJ_MAX
};
diff --git a/include/linux/checkpoint_types.h b/include/linux/checkpoint_types.h
index eb3fdac..84782b0 100644
--- a/include/linux/checkpoint_types.h
+++ b/include/linux/checkpoint_types.h
@@ -86,6 +86,8 @@ struct ckpt_ctx {
struct cred *realcred, *ecred; /* tmp storage for cred at restart */
struct list_head listen_sockets;/* listening parent sockets */
+ int num_devpts_ns; /* must not become > 1 at the moment */
+
struct ckpt_stats stats; /* statistics */
#define CKPT_MSG_LEN 1024
diff --git a/include/linux/devpts_fs.h b/include/linux/devpts_fs.h
index 163a70e..63fbee2 100644
--- a/include/linux/devpts_fs.h
+++ b/include/linux/devpts_fs.h
@@ -14,6 +14,7 @@
#define _LINUX_DEVPTS_FS_H
#include <linux/errno.h>
+#include <linux/checkpoint.h>
#define UNSPECIFIED_PTY_INDEX -1
@@ -30,7 +31,24 @@ struct tty_struct *devpts_get_tty(struct inode *pts_inode, int number);
/* unlink */
void devpts_pty_kill(struct tty_struct *tty);
-#else
+#ifdef CONFIG_CHECKPOINT
+/*
+ * We don't yet support multiple pts mounts in a container, so
+ * all we're doing here is detecting pty's in >1 ptsns. We'll
+ * actually stick the sb on the objhash because that's all there
+ * is. Note that means that when we start checkpointing mounts
+ * and filesystems we'll need to change this.
+ *
+ * We don't need to pin these bc they are pinned by the pty,
+ * which we do have pinned.
+ */
+static const struct ckpt_obj_ops ckpt_obj_ptsns_ops = {
+ .obj_name = "PTS NS",
+ .obj_type = CKPT_OBJ_PTS_NS,
+};
+#endif /* CONFIG_CHECKPOINT */
+
+#else /* CONFIG_UNIX98_PTYS */
/* Dummy stubs in the no-pty case */
static inline int devpts_new_index(struct inode *ptmx_inode) { return -EINVAL; }
@@ -47,7 +65,7 @@ static inline struct tty_struct *devpts_get_tty(struct inode *pts_inode,
}
static inline void devpts_pty_kill(struct tty_struct *tty) { }
-#endif
+#endif /* CONFIG_UNIX98_PTYS */
#endif /* _LINUX_DEVPTS_FS_H */
--
1.7.0.4
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