dump: support SYSV IPC vma

This patch introduces the following changes:

1) introduces new flag VMA_AREA_SYSVIPC to mark corresponding vma entries.
2) enhance task /proc/<pid>/maps parsing to obtain first 5 letters of mapped
   file. If device major file belong to ins equal to 0 (tmpfs) and it's name
   starts with "/SYSV", then this mapping is considered as SYSV IPC and
   corresponding vma entry status is updated with VMA_AREA_SYSVIPC flag.
3) omit dumping of mapping pages for SYSV IPC vmas.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>

include/image.h

@@ -169,6 +169,8 @@ struct ipc_msg_entry {
 #define VMA_ANON_SHARED		(1 <<  8)
 #define VMA_ANON_PRIVATE	(1 <<  9)
 
+#define VMA_AREA_SYSVIPC	(1 <<  10)
+
 #define vma_entry_is(vma, s)	(((vma)->status & (s)) == (s))
 #define vma_entry_len(vma)	((vma)->end - (vma)->start)
 #define final_vma_entry(vma)	((vma)->start == 0 && (vma)->end == 0)

parasite-syscall.c

@@ -448,6 +448,10 @@ int parasite_dump_pages_seized(struct parasite_ctl *ctl, struct list_head *vma_a
 		if (vma_area->vma.status & VMA_FILE_SHARED)
 			continue;
 
+		/* No dumps for SYSV IPC mappings */
+		if (vma_area->vma.status & VMA_AREA_SYSVIPC)
+			continue;
+
 		pr_info_vma(vma_area);
 		parasite_dumppages.vma_entry = vma_area->vma;
 

proc_parse.c

@@ -45,11 +45,14 @@ int parse_maps(pid_t pid, int pid_dir, struct list_head *vma_area_list, bool use
 	while (fgets(big_buffer, sizeof(big_buffer), maps)) {
 		struct stat st_buf;
 		int num;
+		char file_path[6];
 
-		num = sscanf(big_buffer, "%lx-%lx %c%c%c%c %lx %02x:%02x %lu",
+
+		memset(file_path, 0, 6);
+		num = sscanf(big_buffer, "%lx-%lx %c%c%c%c %lx %02x:%02x %lu %5s",
 			     &start, &end, &r, &w, &x, &s, &pgoff, &dev_maj,
-			     &dev_min, &ino);
-		if (num != 10) {
+			     &dev_min, &ino, file_path);
+		if (num < 10) {
 			pr_err("Can't parse: %s", big_buffer);
 			goto err;
 		}
@@ -133,6 +136,11 @@ int parse_maps(pid_t pid, int pid_dir, struct list_head *vma_area_list, bool use
 				vma_area->vma.flags  |= MAP_ANONYMOUS;
 				vma_area->vma.status |= VMA_ANON_SHARED;
 				vma_area->shmid = st_buf.st_ino;
+
+				if (!strcmp(file_path, "/SYSV")) {
+					pr_perror("path: %s\n", file_path);
+					vma_area->vma.status |= VMA_AREA_SYSVIPC;
+				}
 			} else {
 				if (vma_area->vma.flags & MAP_PRIVATE)
 					vma_area->vma.status |= VMA_FILE_PRIVATE;