[CRIU] [PATCH cr 6/6] restore: restore pocesses which share one fdtable

Andrey Vagin avagin at openvz.org
Tue Oct 2 10:07:22 EDT 2012


Currently crtools supports a case when children are shared fd table
with parent.

Here is only two interesting thing.
* Service descriptors should be cloned for each process
  who shared one fd table.
* One task should restore files and other tasks should sleep in this time.

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 cr-dump.c         |   12 +++++++-----
 cr-restore.c      |   35 +++++++++++++++++++++++++++++++----
 files.c           |    6 +-----
 include/crtools.h |    8 ++++++++
 include/files.h   |    1 +
 include/lock.h    |    4 ++++
 include/pstree.h  |    5 +++++
 pstree.c          |    5 ++++-
 8 files changed, 61 insertions(+), 15 deletions(-)

diff --git a/cr-dump.c b/cr-dump.c
index 1b689a3..13ce5db 100644
--- a/cr-dump.c
+++ b/cr-dump.c
@@ -1483,12 +1483,14 @@ static int dump_one_task(struct pstree_item *item)
 
 	ret = dump_task_kobj_ids(item);
 	if (ret)
- 		goto err_cure;
-
-	ret = dump_task_files_seized(parasite_ctl, cr_fdset, dfds);
-	if (ret) {
-		pr_err("Dump files (pid: %d) failed with %d\n", pid, ret);
 		goto err_cure;
+
+	if (!shared_fdtable(item)) {
+		ret = dump_task_files_seized(parasite_ctl, cr_fdset, dfds);
+		if (ret) {
+			pr_err("Dump files (pid: %d) failed with %d\n", pid, ret);
+			goto err_cure;
+		}
 	}
 
 	ret = parasite_dump_pages_seized(parasite_ctl, &vma_area_list, cr_fdset);
diff --git a/cr-restore.c b/cr-restore.c
index 007e13d..69372a0 100644
--- a/cr-restore.c
+++ b/cr-restore.c
@@ -324,13 +324,25 @@ static int pstree_wait_helpers()
 
 static int restore_one_alive_task(int pid, CoreEntry *core)
 {
+	struct pstree_item *child;
 	pr_info("Restoring resources\n");
 
 	if (pstree_wait_helpers())
 		return -1;
 
-	if (prepare_fds(current))
-		return -1;
+	list_for_each_entry(child, &current->children, list) {
+		if (child->state == TASK_HELPER)
+			continue;
+		futex_wait_while_lt(&child->rst->fdt_lock, FDT_LOCK_SYNC);
+	}
+	futex_set_and_wake(&current->rst->fdt_lock, FDT_LOCK_SYNC);
+
+	if (!shared_fdtable(current)) {
+		if (prepare_fds(current))
+			return -1;
+	} else
+		futex_wait_while_lt(&current->parent->rst->fdt_lock, FDT_LOCK_DONE);
+	futex_set_and_wake(&current->rst->fdt_lock, FDT_LOCK_DONE);
 
 	if (prepare_fs(pid))
 		return -1;
@@ -407,6 +419,7 @@ static int restore_one_zombie(int pid, int exit_code)
 {
 	pr_info("Restoring zombie with %d code\n", exit_code);
 
+	futex_set_and_wake(&current->rst->fdt_lock, FDT_LOCK_DONE);
 	if (task_entries != NULL) {
 		futex_dec_and_wake(&task_entries->nr_in_progress);
 		futex_wait_while(&task_entries->start, CR_STATE_RESTORE);
@@ -524,6 +537,9 @@ static inline int fork_with_pid(struct pstree_item *item, unsigned long ns_clone
 	ca.item = item;
 	ca.clone_flags = ns_clone_flags;
 
+	if (shared_fdtable(item))
+		ca.clone_flags |= CLONE_FILES;
+
 	if (!(ca.clone_flags & CLONE_NEWPID)) {
 		char buf[32];
 
@@ -734,9 +750,17 @@ static int restore_task_with_children(void *_arg)
 	int ret;
 	sigset_t blockmask;
 
-	close_safe(&ca->fd);
-
 	current = ca->item;
+	if (!shared_fdtable(current))
+		close_safe(&ca->fd);
+
+	if (ca->clone_flags & CLONE_FILES)
+		ret = clone_service_fd(false);
+	else
+		ret = clone_service_fd(true);
+
+	if (ret != 0)
+		return -1;
 
 	pid = getpid();
 	if (current->pid.virt != pid) {
@@ -768,6 +792,9 @@ static int restore_task_with_children(void *_arg)
 			exit(-1);
 	}
 
+	if (!shared_fdtable(current))
+		close_old_fds(current);
+
 	/*
 	 * The block mask will be restored in sigresturn.
 	 *
diff --git a/files.c b/files.c
index cb34c48..bb53f10 100644
--- a/files.c
+++ b/files.c
@@ -496,7 +496,7 @@ static int open_fdinfos(int pid, struct list_head *list, int state)
 	return ret;
 }
 
-static int close_old_fds(struct pstree_item *me)
+int close_old_fds(struct pstree_item *me)
 {
 	DIR *dir;
 	struct dirent *de;
@@ -533,10 +533,6 @@ int prepare_fds(struct pstree_item *me)
 	u32 ret;
 	int state;
 
-	ret = close_old_fds(me);
-	if (ret)
-		return ret;
-
 	pr_info("Opening fdinfo-s\n");
 
 	for (state = 0; state < ARRAY_SIZE(states); state++) {
diff --git a/include/crtools.h b/include/crtools.h
index c72c0b0..7a56e98 100644
--- a/include/crtools.h
+++ b/include/crtools.h
@@ -218,10 +218,18 @@ struct vma_area {
 #define vma_area_is(vma_area, s)	vma_entry_is(&((vma_area)->vma), s)
 #define vma_area_len(vma_area)		vma_entry_len(&((vma_area)->vma))
 
+enum {
+	FDT_LOCK_INIT = 0,
+	FDT_LOCK_SYNC,
+	FDT_LOCK_DONE,
+};
+
 struct rst_info {
 	struct list_head	fds;
 	struct list_head	eventpoll;
 	struct list_head	tty_slaves;
+
+	futex_t			fdt_lock;
 };
 
 struct pid
diff --git a/include/files.h b/include/files.h
index cc0e46f..7199212 100644
--- a/include/files.h
+++ b/include/files.h
@@ -91,6 +91,7 @@ extern int get_filemap_fd(int pid, VmaEntry *vma_entry);
 extern int prepare_fs(int pid);
 extern int set_fd_flags(int fd, int flags);
 
+extern int close_old_fds(struct pstree_item *me);
 #ifndef AT_EMPTY_PATH
 #define AT_EMPTY_PATH 0x1000
 #endif
diff --git a/include/lock.h b/include/lock.h
index e699a06..c83d4ad 100644
--- a/include/lock.h
+++ b/include/lock.h
@@ -84,6 +84,10 @@ static inline void futex_wait_until(futex_t *f, u32 v)
 static inline void futex_wait_while_gt(futex_t *f, u32 v)
 { futex_wait_if_cond(f, v, <=); }
 
+/* Wait while futex @f value is greater than @v */
+static inline void futex_wait_while_lt(futex_t *f, u32 v)
+{ futex_wait_if_cond(f, v, >=); }
+
 /* Wait while futex @f value is @v */
 static inline void futex_wait_while(futex_t *f, u32 v)
 {
diff --git a/include/pstree.h b/include/pstree.h
index 2da7176..2663cfe 100644
--- a/include/pstree.h
+++ b/include/pstree.h
@@ -23,6 +23,11 @@ struct pstree_item {
 	struct rst_info		*rst;
 };
 
+static inline int shared_fdtable(struct pstree_item *item) {
+	return (item->parent && item->parent->state != TASK_HELPER &&
+		item->files_id && item->files_id == item->parent->files_id);
+}
+
 extern void free_pstree(struct pstree_item *root_item);
 extern struct pstree_item *__alloc_pstree_item(bool rst);
 #define alloc_pstree_item() __alloc_pstree_item(false)
diff --git a/pstree.c b/pstree.c
index 1672b26..057cad3 100644
--- a/pstree.c
+++ b/pstree.c
@@ -5,6 +5,7 @@
 #include "pstree.h"
 #include "restorer.h"
 #include "util.h"
+#include "lock.h"
 
 #include "protobuf.h"
 #include "protobuf/pstree.pb-c.h"
@@ -41,6 +42,8 @@ struct pstree_item *__alloc_pstree_item(bool rst)
 		item->rst = shmalloc(sizeof(item->rst[0]));
 		if (!item->rst)
 			return NULL;
+
+		futex_init(&item->rst->fdt_lock);
 	}
 
 	INIT_LIST_HEAD(&item->children);
@@ -250,7 +253,7 @@ int prepare_pstree_ids(void)
 		if (item->sid == root_item->sid || item->sid == item->pid.virt)
 			continue;
 
-		helper = alloc_pstree_item();
+		helper = alloc_pstree_item_with_rst();
 		if (helper == NULL)
 			return -1;
 		helper->sid = item->sid;
-- 
1.7.1



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