Now we can do "external" checkpoint, i.e. act on another task. sys_checkpoint() now looks up the target pid (in our namespace) and checkpoints that corresponding task. That task should be the root of a container.
sys_restart() remains the same, as the restart is always done in the context of the restarting task. Changelog[v14]: - Refuse non-self checkpoint if target task isn't frozen Changelog[v12]: - Replace obsolete ckpt_debug() with pr_debug() Changelog[v11]: - Copy contents of 'init->fs->root' instead of pointing to them Changelog[v10]: - Grab vfs root of container init, rather than current process Signed-off-by: Oren Laadan <[email protected]> --- checkpoint/checkpoint.c | 77 ++++++++++++++++++++++++++++++++++++-- checkpoint/restart.c | 4 +- checkpoint/sys.c | 6 +++ include/linux/checkpoint_types.h | 2 + 4 files changed, 83 insertions(+), 6 deletions(-) diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c index 9abdf73..b741557 100644 --- a/checkpoint/checkpoint.c +++ b/checkpoint/checkpoint.c @@ -12,7 +12,11 @@ #define CKPT_DFLAG CKPT_DSYS #include <linux/version.h> +#include <linux/sched.h> +#include <linux/freezer.h> +#include <linux/ptrace.h> #include <linux/time.h> +#include <linux/fs_struct.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/fdtable.h> @@ -161,22 +165,87 @@ static int checkpoint_write_tail(struct ckpt_ctx *ctx) return ret; } -static int ckpt_ctx_checkpoint(struct ckpt_ctx *ctx, pid_t pid) +static int get_container(struct ckpt_ctx *ctx, pid_t pid) +{ + struct task_struct *task = NULL; + struct nsproxy *nsproxy = NULL; + int err = -ESRCH; + + ctx->root_pid = pid; + + read_lock(&tasklist_lock); + task = find_task_by_vpid(pid); + if (task) + get_task_struct(task); + read_unlock(&tasklist_lock); + + if (!task) + goto out; + +#if 0 /* enable to use containers */ + if (!is_container_init(task)) { + err = -EINVAL; + goto out; + } +#endif + + if (!ptrace_may_access(task, PTRACE_MODE_READ)) { + err = -EPERM; + goto out; + } + + /* verify that the task is frozen (unless self) */ + if (task != current && !frozen(task)) + return -EBUSY; + + /* FIX: add support for ptraced tasks */ + if (task_ptrace(task)) + return -EBUSY; + + rcu_read_lock(); + nsproxy = task_nsproxy(task); + if (nsproxy) + get_nsproxy(nsproxy); + rcu_read_unlock(); + + if (!nsproxy) + goto out; + + ctx->root_task = task; + ctx->root_nsproxy = nsproxy; + + return 0; + + out: + if (task) + put_task_struct(task); + return err; +} + +/* setup checkpoint-specific parts of ctx */ +static int ctx_checkpoint(struct ckpt_ctx *ctx, pid_t pid) { struct fs_struct *fs; + int ret; ctx->root_pid = pid; + ret = get_container(ctx, pid); + if (ret < 0) + return ret; + /* * assume checkpointer is in container's root vfs * FIXME: this works for now, but will change with real containers */ - fs = current->fs; + task_lock(ctx->root_task); + fs = ctx->root_task->fs; read_lock(&fs->lock); ctx->fs_mnt = fs->root; path_get(&ctx->fs_mnt); read_unlock(&fs->lock); + task_unlock(ctx->root_task); return 0; } @@ -185,13 +254,13 @@ int do_checkpoint(struct ckpt_ctx *ctx, pid_t pid) { int ret; - ret = ckpt_ctx_checkpoint(ctx, pid); + ret = ctx_checkpoint(ctx, pid); if (ret < 0) goto out; ret = checkpoint_write_header(ctx); if (ret < 0) goto out; - ret = checkpoint_task(ctx, current); + ret = checkpoint_task(ctx, ctx->root_task); if (ret < 0) goto out; ret = checkpoint_write_tail(ctx); diff --git a/checkpoint/restart.c b/checkpoint/restart.c index ecf2cf0..637de90 100644 --- a/checkpoint/restart.c +++ b/checkpoint/restart.c @@ -334,7 +334,7 @@ static int restore_read_tail(struct ckpt_ctx *ctx) } /* setup restart-specific parts of ctx */ -static int ckpt_ctx_restart(struct ckpt_ctx *ctx) +static int ctx_restart(struct ckpt_ctx *ctx, pid_t pid) { return 0; } @@ -343,7 +343,7 @@ int do_restart(struct ckpt_ctx *ctx, pid_t pid) { int ret; - ret = ckpt_ctx_restart(ctx); + ret = ctx_restart(ctx, pid); if (ret < 0) return ret; ret = restore_read_header(ctx); diff --git a/checkpoint/sys.c b/checkpoint/sys.c index 76d5d66..0b7245a 100644 --- a/checkpoint/sys.c +++ b/checkpoint/sys.c @@ -12,6 +12,7 @@ #define CKPT_DFLAG CKPT_DSYS #include <linux/sched.h> +#include <linux/nsproxy.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/file.h> @@ -205,6 +206,11 @@ static void ckpt_ctx_free(struct ckpt_ctx *ctx) ckpt_pgarr_free(ctx); ckpt_obj_hash_free(ctx); + if (ctx->root_nsproxy) + put_nsproxy(ctx->root_nsproxy); + if (ctx->root_task) + put_task_struct(ctx->root_task); + kfree(ctx); } diff --git a/include/linux/checkpoint_types.h b/include/linux/checkpoint_types.h index 12f0ec5..d98ba71 100644 --- a/include/linux/checkpoint_types.h +++ b/include/linux/checkpoint_types.h @@ -22,6 +22,8 @@ struct ckpt_ctx { int crid; /* unique checkpoint id */ pid_t root_pid; /* container identifier */ + struct task_struct *root_task; /* container root task */ + struct nsproxy *root_nsproxy; /* container root nsproxy */ unsigned long flags; unsigned long oflags; /* restart: old flags */ -- 1.5.4.3 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
