[PATCH 37/38] C/R: checkpoint/restore opened files
Alexey Dobriyan
adobriyan at gmail.com
Thu May 21 21:55:31 PDT 2009
File descriptor is dumped as formally an object, despite it can't be shared
by itself, only files_struct can.
Opening is done, veryfying that we opened right file, restoration of file
position and nothing more.
Signed-off-by: Alexey Dobriyan <adobriyan at gmail.com>
---
include/linux/kstate-image.h | 16 +++
include/linux/kstate.h | 6 +
kernel/kstate/cpt-sys.c | 6 +
kernel/kstate/kstate-context.c | 6 +
kernel/kstate/kstate-file.c | 201 ++++++++++++++++++++++++++++++++++++++++
kernel/kstate/kstate-object.c | 4 +
kernel/kstate/kstate-task.c | 54 +++++++++++
7 files changed, 293 insertions(+), 0 deletions(-)
diff --git a/include/linux/kstate-image.h b/include/linux/kstate-image.h
index 108bb2d..700fc62 100644
--- a/include/linux/kstate-image.h
+++ b/include/linux/kstate-image.h
@@ -54,6 +54,8 @@ struct kstate_image_header {
#define KSTATE_OBJ_USER_STRUCT 14
#define KSTATE_OBJ_USER_NS 15
#define KSTATE_OBJ_PID 16
+#define KSTATE_OBJ_FILES_STRUCT 17
+#define KSTATE_OBJ_FD 18
struct kstate_object_header {
__u32 obj_type;
@@ -77,6 +79,7 @@ struct kstate_image_task_struct {
kstate_ref_t ref_mm;
kstate_ref_t ref_nsproxy;
+ kstate_ref_t ref_files;
kstate_ref_t ref_real_cred;
kstate_ref_t ref_cred;
@@ -318,4 +321,17 @@ struct kstate_image_pid {
__u32 level;
__u32 nr[1];
} __packed;
+
+struct kstate_image_files_struct {
+ struct kstate_object_header hdr;
+} __packed;
+
+struct kstate_image_fd {
+ struct kstate_object_header hdr;
+
+ kstate_ref_t ref_file;
+ __u32 fd;
+#define KSTATE_FD_FLAGS_CLOEXEC (1 << 0)
+ __u32 fd_flags;
+} __packed;
#endif
diff --git a/include/linux/kstate.h b/include/linux/kstate.h
index 99a4345..2473381 100644
--- a/include/linux/kstate.h
+++ b/include/linux/kstate.h
@@ -23,6 +23,7 @@ struct kstate_object {
enum kstate_context_obj_type {
KSTATE_CTX_CRED,
KSTATE_CTX_FILE,
+ KSTATE_CTX_FILES_STRUCT,
KSTATE_CTX_GROUP_INFO,
#ifdef CONFIG_IPC_NS
KSTATE_CTX_IPC_NS,
@@ -149,6 +150,11 @@ int kstate_collect_all_pid(struct kstate_context *ctx);
int kstate_dump_all_pid(struct kstate_context *ctx);
int kstate_restore_pid(struct kstate_context *ctx, kstate_ref_t *ref);
+int kstate_collect_all_files_struct(struct kstate_context *ctx);
+int kstate_dump_all_files_struct(struct kstate_context *ctx);
+int kstate_restore_files_struct(struct kstate_context *ctx, kstate_ref_t *ref);
+int kstate_restore_fd(struct kstate_context *ctx, kstate_pos_t pos);
+
#if defined(CONFIG_X86_32) || defined(CONFIG_X86_64)
extern const __u32 kstate_kernel_arch;
int kstate_arch_check_image_header(struct kstate_image_header *i);
diff --git a/kernel/kstate/cpt-sys.c b/kernel/kstate/cpt-sys.c
index 119940d..05fc9d8 100644
--- a/kernel/kstate/cpt-sys.c
+++ b/kernel/kstate/cpt-sys.c
@@ -86,6 +86,9 @@ static int kstate_collect(struct kstate_context *ctx)
rv = kstate_collect_all_mm_struct(ctx);
if (rv < 0)
return rv;
+ rv = kstate_collect_all_files_struct(ctx);
+ if (rv < 0)
+ return rv;
rv = kstate_collect_all_file(ctx);
if (rv < 0)
return rv;
@@ -175,6 +178,9 @@ static int kstate_dump(struct kstate_context *ctx)
rv = kstate_dump_all_file(ctx);
if (rv < 0)
return rv;
+ rv = kstate_dump_all_files_struct(ctx);
+ if (rv < 0)
+ return rv;
rv = kstate_dump_all_mm_struct(ctx);
if (rv < 0)
return rv;
diff --git a/kernel/kstate/kstate-context.c b/kernel/kstate/kstate-context.c
index 9acb441..3e1589f 100644
--- a/kernel/kstate/kstate-context.c
+++ b/kernel/kstate/kstate-context.c
@@ -1,4 +1,5 @@
/* Copyright (C) 2000-2009 Parallels Holdings, Ltd. */
+#include <linux/fdtable.h>
#include <linux/file.h>
#include <linux/ipc_namespace.h>
#include <linux/list.h>
@@ -47,6 +48,11 @@ void kstate_context_destroy(struct kstate_context *ctx)
list_del(&obj->o_list);
kfree(obj);
}
+ for_each_kstate_object_safe(ctx, obj, tmp, KSTATE_CTX_FILES_STRUCT) {
+ put_files_struct((struct files_struct *)obj->o_obj);
+ list_del(&obj->o_list);
+ kfree(obj);
+ }
for_each_kstate_object_safe(ctx, obj, tmp, KSTATE_CTX_GROUP_INFO) {
put_group_info((struct group_info *)obj->o_obj);
list_del(&obj->o_list);
diff --git a/kernel/kstate/kstate-file.c b/kernel/kstate/kstate-file.c
index f378be3..b11828b 100644
--- a/kernel/kstate/kstate-file.c
+++ b/kernel/kstate/kstate-file.c
@@ -58,6 +58,20 @@ int kstate_collect_all_file(struct kstate_context *ctx)
struct kstate_object *obj;
int rv;
+ for_each_kstate_object(ctx, obj, KSTATE_CTX_FILES_STRUCT) {
+ struct files_struct *files = obj->o_obj;
+ struct file *file;
+ int fd;
+
+ for (fd = 0; fd < files->fdt->max_fds; fd++) {
+ file = fcheck_files(files, fd);
+ if (!file)
+ continue;
+ rv = collect_file(ctx, file);
+ if (rv < 0)
+ return rv;
+ }
+ }
for_each_kstate_object(ctx, obj, KSTATE_CTX_MM_STRUCT) {
struct mm_struct *mm = obj->o_obj;
struct vm_area_struct *vma;
@@ -232,3 +246,190 @@ out_free_image:
pr_debug("%s: return %d, ref {%llu, %u}\n", __func__, rv, (unsigned long long)ref->pos, ref->id);
return rv;
}
+
+static int collect_files_struct(struct kstate_context *ctx, struct files_struct *files)
+{
+ int rv;
+
+ rv = kstate_collect_object(ctx, files, KSTATE_CTX_FILES_STRUCT);
+ pr_debug("collect files_struct %p: rv %d\n", files, rv);
+ return rv;
+}
+
+int kstate_collect_all_files_struct(struct kstate_context *ctx)
+{
+ struct kstate_object *obj;
+ int rv;
+
+ for_each_kstate_object(ctx, obj, KSTATE_CTX_TASK_STRUCT) {
+ struct task_struct *tsk = obj->o_obj;
+
+ rv = collect_files_struct(ctx, tsk->files);
+ if (rv < 0)
+ return rv;
+ }
+ for_each_kstate_object(ctx, obj, KSTATE_CTX_FILES_STRUCT) {
+ struct files_struct *files = obj->o_obj;
+ unsigned int cnt = atomic_read(&files->count);
+
+ if (obj->o_count + 1 != cnt) {
+ pr_err("files_struct %p has external references %lu:%u\n", files, obj->o_count, cnt);
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
+static int dump_fd(struct kstate_context *ctx, struct files_struct *files, int fd, struct file *file)
+{
+ struct kstate_image_fd *i;
+ struct kstate_object *tmp;
+ int rv;
+
+ i = kstate_prepare_image(KSTATE_OBJ_FD, sizeof(*i));
+ if (!i)
+ return -ENOMEM;
+ /*
+ * fd doesn't get id because it can't be shared by itself,
+ * only files_struct can. Assign some deterministic id.
+ */
+ i->hdr.obj_id = 0;
+
+ tmp = find_kstate_obj_by_ptr(ctx, file, KSTATE_CTX_FILE);
+ i->ref_file = tmp->o_ref;
+ i->fd = fd;
+ i->fd_flags = 0;
+ if (FD_ISSET(fd, files->fdt->close_on_exec))
+ i->fd_flags |= KSTATE_FD_FLAGS_CLOEXEC;
+
+ rv = kstate_write(ctx, i, sizeof(*i));
+ kfree(i);
+ pr_debug("dump fd %d: rv %d, files_struct %p, file %p\n", fd, rv, files, file);
+ return rv;
+}
+
+static int dump_all_fd(struct kstate_context *ctx, struct files_struct *files)
+{
+ struct file *file;
+ int fd;
+ int rv;
+
+ for (fd = 0; fd < files->fdt->max_fds; fd++) {
+ file = fcheck_files(files, fd);
+ if (!file)
+ continue;
+ rv = dump_fd(ctx, files, fd, file);
+ if (rv < 0)
+ return rv;
+ }
+ return 0;
+}
+
+static int dump_files_struct(struct kstate_context *ctx, struct kstate_object *obj)
+{
+ struct files_struct *files = obj->o_obj;
+ struct kstate_image_files_struct *i;
+ int rv;
+
+ i = kstate_prepare_image(KSTATE_OBJ_FILES_STRUCT, sizeof(*i));
+ if (!i)
+ return -ENOMEM;
+
+ rv = kstate_write_image(ctx, i, sizeof(*i), obj);
+ kfree(i);
+ pr_debug("dump files_struct %p: ref {%llu, %u}, rv %d\n", files, (unsigned long long)obj->o_ref.pos, obj->o_ref.id, rv);
+ return rv;
+}
+
+int kstate_dump_all_files_struct(struct kstate_context *ctx)
+{
+ struct kstate_object *obj;
+ int rv;
+
+ for_each_kstate_object(ctx, obj, KSTATE_CTX_FILES_STRUCT) {
+ struct files_struct *files = obj->o_obj;
+
+ rv = dump_files_struct(ctx, obj);
+ if (rv < 0)
+ return rv;
+ rv = dump_all_fd(ctx, files);
+ if (rv < 0)
+ return rv;
+ }
+ return 0;
+}
+
+int kstate_restore_fd(struct kstate_context *ctx, kstate_pos_t pos)
+{
+ kstate_ref_t ref = { .pos = pos, .id = 0 };
+ struct kstate_image_fd *i;
+ struct file *file;
+ int fd;
+ unsigned int flags;
+ struct kstate_object *tmp;
+ int rv;
+
+ i = kstate_read_image(ctx, &ref, KSTATE_OBJ_FD, sizeof(*i));
+ if (IS_ERR(i))
+ return PTR_ERR(i);
+
+ tmp = find_kstate_obj_by_ref(ctx, &i->ref_file, KSTATE_CTX_FILE);
+ if (!tmp) {
+ rv = kstate_restore_file(ctx, &i->ref_file);
+ if (rv < 0)
+ goto out_free_image;
+ tmp = find_kstate_obj_by_ref(ctx, &i->ref_file, KSTATE_CTX_FILE);
+ }
+ file = tmp->o_obj;
+
+ flags = 0;
+ if (i->fd_flags & KSTATE_FD_FLAGS_CLOEXEC)
+ flags |= O_CLOEXEC;
+ fd = alloc_fd(i->fd, flags);
+ if (fd != i->fd)
+ rv = (fd < 0) ? fd : -EINVAL;
+ else
+ rv = 0;
+ kfree(i);
+ if (rv < 0)
+ return rv;
+
+ get_file(file);
+ fd_install(fd, file);
+ return 0;
+
+out_free_image:
+ kfree(i);
+ return rv;
+}
+
+int kstate_restore_files_struct(struct kstate_context *ctx, kstate_ref_t *ref)
+{
+ struct kstate_image_files_struct *i;
+ struct files_struct *files;
+ int rv;
+
+ i = kstate_read_image(ctx, ref, KSTATE_OBJ_FILES_STRUCT, sizeof(*i));
+ if (IS_ERR(i))
+ return PTR_ERR(i);
+
+ files = kmem_cache_zalloc(files_cachep, GFP_KERNEL);
+ if (!files) {
+ kfree(i);
+ return -ENOMEM;
+ }
+ atomic_set(&files->count, 1);
+ files->fdt = &files->fdtab;
+ files->fdt->max_fds = NR_OPEN_DEFAULT;
+ files->fdt->fd = files->fd_array;
+ files->fdt->close_on_exec = (fd_set *)&files->close_on_exec_init;
+ files->fdt->open_fds = (fd_set *)&files->open_fds_init;
+ spin_lock_init(&files->file_lock);
+ kfree(i);
+
+ rv = kstate_restore_object(ctx, files, KSTATE_CTX_FILES_STRUCT, ref);
+ if (rv < 0)
+ kmem_cache_free(files_cachep, files);
+ pr_debug("restore files_struct %p: ref {%llu, %u}, rv %d\n", files, (unsigned long long)ref->pos, ref->id, rv);
+ return rv;
+}
diff --git a/kernel/kstate/kstate-object.c b/kernel/kstate/kstate-object.c
index ab026f0..bc27985 100644
--- a/kernel/kstate/kstate-object.c
+++ b/kernel/kstate/kstate-object.c
@@ -1,4 +1,5 @@
/* Copyright (C) 2000-2009 Parallels Holdings, Ltd. */
+#include <linux/fdtable.h>
#include <linux/fs.h>
#include <linux/ipc_namespace.h>
#include <linux/mm_types.h>
@@ -42,6 +43,9 @@ int kstate_collect_object(struct kstate_context *ctx, void *p, enum kstate_conte
case KSTATE_CTX_FILE:
get_file((struct file *)obj->o_obj);
break;
+ case KSTATE_CTX_FILES_STRUCT:
+ atomic_inc(&((struct files_struct *)obj->o_obj)->count);
+ break;
case KSTATE_CTX_GROUP_INFO:
get_group_info((struct group_info *)obj->o_obj);
break;
diff --git a/kernel/kstate/kstate-task.c b/kernel/kstate/kstate-task.c
index 4a3524e..101fcb8 100644
--- a/kernel/kstate/kstate-task.c
+++ b/kernel/kstate/kstate-task.c
@@ -1,4 +1,5 @@
/* Copyright (C) 2000-2009 Parallels Holdings, Ltd. */
+#include <linux/fdtable.h>
#include <linux/kthread.h>
#include <linux/nsproxy.h>
#include <linux/pid_namespace.h>
@@ -135,6 +136,9 @@ static int dump_task_struct(struct kstate_context *ctx, struct kstate_object *ob
tmp = find_kstate_obj_by_ptr(ctx, tsk->pids[PIDTYPE_SID].pid, KSTATE_CTX_PID);
i->ref_sid = tmp->o_ref;
+ tmp = find_kstate_obj_by_ptr(ctx, tsk->files, KSTATE_CTX_FILES_STRUCT);
+ i->ref_files = tmp->o_ref;
+
BUILD_BUG_ON(sizeof(i->comm) != sizeof(tsk->comm));
strlcpy((char *)i->comm, (const char *)tsk->comm, sizeof(i->comm));
@@ -351,6 +355,53 @@ static int restore_sid(struct kstate_context *ctx, kstate_ref_t *ref)
return 0;
}
+static int restore_all_fd(struct kstate_context *ctx, kstate_pos_t pos)
+{
+ struct kstate_object_header hdr;
+ int rv;
+
+ while (1) {
+ rv = kstate_pread(ctx, &hdr, sizeof(hdr), pos);
+ if (rv < 0)
+ return rv;
+ if (hdr.obj_len < sizeof(hdr))
+ return -EINVAL;
+
+ if (hdr.obj_type == KSTATE_OBJ_FD) {
+ rv = kstate_restore_fd(ctx, pos);
+ if (rv < 0)
+ return rv;
+ } else
+ return 0;
+ pos += hdr.obj_len;
+ }
+}
+
+static int restore_files(struct kstate_context *ctx, kstate_ref_t *ref)
+{
+ struct files_struct *files;
+ struct kstate_object *tmp;
+ int restore_fd;
+ int rv;
+
+ tmp = find_kstate_obj_by_ref(ctx, ref, KSTATE_CTX_FILES_STRUCT);
+ if (!tmp) {
+ rv = kstate_restore_files_struct(ctx, ref);
+ if (rv < 0)
+ return rv;
+ tmp = find_kstate_obj_by_ref(ctx, ref, KSTATE_CTX_FILES_STRUCT);
+ restore_fd = 1;
+ } else
+ restore_fd = 0;
+ files = tmp->o_obj;
+
+ atomic_inc(&files->count);
+ reset_files_struct(files);
+ if (restore_fd)
+ return restore_all_fd(ctx, ref->pos + sizeof(struct kstate_image_files_struct));
+ return 0;
+}
+
struct task_struct_restore_context {
struct kstate_context *ctx;
struct kstate_image_task_struct *i;
@@ -414,6 +465,9 @@ static int task_struct_restorer(void *_tsk_ctx)
rv = restore_sid(ctx, &i->ref_sid);
if (rv < 0)
goto out;
+ rv = restore_files(ctx, &i->ref_files);
+ if (rv < 0)
+ goto out;
out:
tsk_ctx->rv = rv;
--
1.5.6.5
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