[PATCH 12/12] add logfd to c/r api

[serue@xxxxxxxxxx]

From: Serge E. Hallyn <serue@xxxxxxxxxx>

and write msgs to user-provided logfile if one exists.

Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
 checkpoint/objhash.c             |    2 ++
 checkpoint/sys.c                 |   25 ++++++++++++++++++-------
 include/linux/checkpoint_types.h |    1 +
 include/linux/syscalls.h         |    5 +++--
 4 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/checkpoint/objhash.c b/checkpoint/objhash.c
index 5d72d04..92c07d2 100644
--- a/checkpoint/objhash.c
+++ b/checkpoint/objhash.c
@@ -858,6 +858,8 @@ int ckpt_obj_contained(struct ckpt_ctx *ctx)
 
 	/* account for ctx->file reference (if in the table already) */
 	ckpt_obj_users_inc(ctx, ctx->file, 1);
+	if (ctx->logfile)
+		ckpt_obj_users_inc(ctx, ctx->logfile, 1);
 	/* account for ctx->root_nsproxy reference (if in the table already) */
 	ckpt_obj_users_inc(ctx, ctx->root_nsproxy, 1);
 
diff --git a/checkpoint/sys.c b/checkpoint/sys.c
index f50167a..dddf1a8 100644
--- a/checkpoint/sys.c
+++ b/checkpoint/sys.c
@@ -204,6 +204,8 @@ static void ckpt_ctx_free(struct ckpt_ctx *ctx)
 
 	if (ctx->file)
 		fput(ctx->file);
+	if (ctx->logfile)
+		fput(ctx->logfile);
 
 	ckpt_obj_hash_free(ctx);
 	path_put(&ctx->fs_mnt);
@@ -225,7 +227,7 @@ static void ckpt_ctx_free(struct ckpt_ctx *ctx)
 }
 
 static struct ckpt_ctx *ckpt_ctx_alloc(int fd, unsigned long uflags,
-				       unsigned long kflags)
+				       unsigned long kflags, int logfd)
 {
 	struct ckpt_ctx *ctx;
 	int err;
@@ -256,6 +258,13 @@ static struct ckpt_ctx *ckpt_ctx_alloc(int fd, unsigned long uflags,
 	if (!ctx->file)
 		goto err;
 
+	if (logfd == -1)
+		goto skiplogfd;
+	ctx->logfile = fget(logfd);
+	if (!ctx->logfile)
+		goto err;
+
+skiplogfd:
 	err = -ENOMEM;
 	if (ckpt_obj_hash_alloc(ctx) < 0)
 		goto err;
@@ -479,14 +488,13 @@ void _ckpt_msg_complete(struct ckpt_ctx *ctx)
 			printk(KERN_NOTICE "c/r: error string unsaved (%d): %s\n",
 			       ret, ctx->msg+1);
 	}
-#if 0
+
 	if (ctx->logfile) {
 		mm_segment_t fs = get_fs();
 		set_fs(KERNEL_DS);
 		ret = _ckpt_kwrite(ctx->logfile, ctx->msg+1, ctx->msglen-1);
 		set_fs(fs);
 	}
-#endif
 #ifdef CONFIG_CHECKPOINT_DEBUG
 	printk(KERN_DEBUG "%s", ctx->msg+1);
 #endif
@@ -520,11 +528,13 @@ void do_ckpt_msg(struct ckpt_ctx *ctx, char *fmt, ...)
  * @pid: pid of the container init(1) process
  * @fd: file to which dump the checkpoint image
  * @flags: checkpoint operation flags
+ * @logfd: fd to which to dump debug and error messages
  *
  * Returns positive identifier on success, 0 when returning from restart
  * or negative value on error
  */
-SYSCALL_DEFINE3(checkpoint, pid_t, pid, int, fd, unsigned long, flags)
+SYSCALL_DEFINE4(checkpoint, pid_t, pid, int, fd, unsigned long, flags,
+		int, logfd)
 {
 	struct ckpt_ctx *ctx;
 	long ret;
@@ -537,7 +547,7 @@ SYSCALL_DEFINE3(checkpoint, pid_t, pid, int, fd, unsigned long, flags)
 
 	if (pid == 0)
 		pid = task_pid_vnr(current);
-	ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_CHECKPOINT);
+	ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_CHECKPOINT, logfd);
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
@@ -555,11 +565,12 @@ SYSCALL_DEFINE3(checkpoint, pid_t, pid, int, fd, unsigned long, flags)
  * @pid: pid of task root (in coordinator's namespace), or 0
  * @fd: file from which read the checkpoint image
  * @flags: restart operation flags
+ * @logfd: fd to which to dump debug and error messages
  *
  * Returns negative value on error, or otherwise returns in the realm
  * of the original checkpoint
  */
-SYSCALL_DEFINE3(restart, pid_t, pid, int, fd, unsigned long, flags)
+SYSCALL_DEFINE4(restart, pid_t, pid, int, fd, unsigned long, flags, int, logfd)
 {
 	struct ckpt_ctx *ctx = NULL;
 	long ret;
@@ -572,7 +583,7 @@ SYSCALL_DEFINE3(restart, pid_t, pid, int, fd, unsigned long, flags)
 		return -EPERM;
 
 	if (pid)
-		ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_RESTART);
+		ctx = ckpt_ctx_alloc(fd, flags, CKPT_CTX_RESTART, logfd);
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
diff --git a/include/linux/checkpoint_types.h b/include/linux/checkpoint_types.h
index 6771b9f..3c5e9f1 100644
--- a/include/linux/checkpoint_types.h
+++ b/include/linux/checkpoint_types.h
@@ -48,6 +48,7 @@ struct ckpt_ctx {
 	unsigned long oflags;	/* restart: uflags from checkpoint */
 
 	struct file *file;	/* input/output file */
+	struct file *logfile;	/* debug log file */
 	loff_t total;		/* total read/written */
 
 	atomic_t refcount;
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 33bce6e..4fce331 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -754,8 +754,9 @@ asmlinkage long sys_pselect6(int, fd_set __user *, fd_set __user *,
 asmlinkage long sys_ppoll(struct pollfd __user *, unsigned int,
 			  struct timespec __user *, const sigset_t __user *,
 			  size_t);
-asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags);
-asmlinkage long sys_restart(pid_t pid, int fd, unsigned long flags);
+asmlinkage long sys_checkpoint(pid_t pid, int fd, unsigned long flags,
+			       int logfd);
+asmlinkage long sys_restart(pid_t pid, int fd, unsigned long flags, int logfd);
 
 int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
 
-- 
1.6.1

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