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restore: generalize mechanism of remapping memory to restorer (v2)

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Sometime we want to have a shared mapping in restorer. E.g. A storage
for shared memory entries. This entries contains locks, which should
be released in restorer.

v2: fixed according to Pavel's comments

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin
2012-01-17 15:28:13 +03:00
parent 31e99b7b37
commit fb177e0312
1 changed files with 7 additions and 13 deletions
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20
cr-restore.c
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@@ -334,14 +334,14 @@ static int prepare_pipes_pid(int pid)
return 0; return 0;
} }
static int shmem_remap(struct shmems *old_addr, struct shmems *new_addr) static int shmem_remap(void *old_addr, void *new_addr, unsigned long size)
{ {
char path[PATH_MAX]; char path[PATH_MAX];
int fd; int fd;
void *ret; void *ret;
sprintf(path, "/proc/self/map_files/%p-%p", sprintf(path, "/proc/self/map_files/%p-%p",
old_addr, (void *)old_addr + SHMEMS_SIZE); old_addr, (void *)old_addr + size);
fd = open(path, O_RDWR); fd = open(path, O_RDWR);
if (fd < 0) { if (fd < 0) {
@@ -349,18 +349,13 @@ static int shmem_remap(struct shmems *old_addr, struct shmems *new_addr)
return -1; return -1;
} }
ret = mmap(new_addr, SHMEMS_SIZE, PROT_READ | PROT_WRITE, ret = mmap(new_addr, size, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_FIXED, fd, 0); MAP_SHARED | MAP_FIXED, fd, 0);
if (ret != new_addr) { if (ret != new_addr) {
pr_perror("mmap failed\n"); pr_perror("mmap failed\n");
return -1; return -1;
} }
if (new_addr->nr_shmems != old_addr->nr_shmems) {
pr_err("shmem_remap failed\n");
return -1;
}
close(fd); close(fd);
return 0; return 0;
} }
@@ -1289,7 +1284,6 @@ static void sigreturn_restore(pid_t pstree_pid, pid_t pid)
{ {
long restore_task_code_len, restore_task_vma_len; long restore_task_code_len, restore_task_vma_len;
long restore_thread_code_len, restore_thread_vma_len; long restore_thread_code_len, restore_thread_vma_len;
long restore_shmem_vma_len;
void *exec_mem = MAP_FAILED; void *exec_mem = MAP_FAILED;
void *restore_thread_exec_start; void *restore_thread_exec_start;
@@ -1321,7 +1315,6 @@ static void sigreturn_restore(pid_t pstree_pid, pid_t pid)
restore_task_vma_len = 0; restore_task_vma_len = 0;
restore_thread_code_len = 0; restore_thread_code_len = 0;
restore_thread_vma_len = 0; restore_thread_vma_len = 0;
restore_shmem_vma_len = SHMEMS_SIZE;
pid_dir = open_pid_proc(pid); pid_dir = open_pid_proc(pid);
if (pid_dir < 0) if (pid_dir < 0)
@@ -1336,6 +1329,7 @@ static void sigreturn_restore(pid_t pstree_pid, pid_t pid)
BUILD_BUG_ON(sizeof(struct task_restore_core_args) & 1); BUILD_BUG_ON(sizeof(struct task_restore_core_args) & 1);
BUILD_BUG_ON(sizeof(struct thread_restore_args) & 1); BUILD_BUG_ON(sizeof(struct thread_restore_args) & 1);
BUILD_BUG_ON(SHMEMS_SIZE % PAGE_SIZE);
fd_pstree = open_image_ro_nocheck(FMT_FNAME_PSTREE, pstree_pid); fd_pstree = open_image_ro_nocheck(FMT_FNAME_PSTREE, pstree_pid);
if (fd_pstree < 0) if (fd_pstree < 0)
@@ -1427,7 +1421,7 @@ static void sigreturn_restore(pid_t pstree_pid, pid_t pid)
exec_mem_hint = restorer_get_vma_hint(pid, &self_vma_list, exec_mem_hint = restorer_get_vma_hint(pid, &self_vma_list,
restore_task_vma_len + restore_task_vma_len +
restore_thread_vma_len + restore_thread_vma_len +
restore_shmem_vma_len); SHMEMS_SIZE);
if (exec_mem_hint == -1) { if (exec_mem_hint == -1) {
pr_err("No suitable area for task_restore bootstrap (%dK)\n", pr_err("No suitable area for task_restore bootstrap (%dK)\n",
restore_task_vma_len + restore_thread_vma_len); restore_task_vma_len + restore_thread_vma_len);
@@ -1484,15 +1478,15 @@ static void sigreturn_restore(pid_t pstree_pid, pid_t pid)
shmems_ref = (struct shmems *)(exec_mem_hint + shmems_ref = (struct shmems *)(exec_mem_hint +
restore_task_vma_len + restore_task_vma_len +
restore_thread_vma_len); restore_thread_vma_len);
ret = shmem_remap(shmems, shmems_ref); ret = shmem_remap(shmems, shmems_ref, SHMEMS_SIZE);
if (ret < 0) if (ret < 0)
goto err; goto err;
task_args->shmems = shmems_ref;
/* /*
* Arguments for task restoration. * Arguments for task restoration.
*/ */
task_args->pid = pid; task_args->pid = pid;
task_args->shmems = shmems_ref;
task_args->fd_core = fd_core; task_args->fd_core = fd_core;
task_args->fd_self_vmas = fd_self_vmas; task_args->fd_self_vmas = fd_self_vmas;