pipe/fifo: Fix and cleanup data restore

Make it in two stages.

First -- collect pipe data into hash without checking for pipe/fifo existance.
Next -- when pipe/fifo gets restored walk the hash and search where the pipe data
is.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

fifo.c

@@ -73,6 +73,8 @@ int dump_fifo(struct fd_parms *p, int lfd, const struct cr_fdset *set)
 	return do_dump_gen_file(p, lfd, &fifo_ops, set);
 }
 
+static struct pipe_data_rst *pd_hash_fifo[PIPE_DATA_HASH_SIZE];
+
 static int do_open_fifo(struct reg_file_info *rfi, void *arg)
 {
 	struct fifo_info *info = arg;
@@ -96,13 +98,12 @@ static int do_open_fifo(struct reg_file_info *rfi, void *arg)
 		goto out;
 	}
 
-	if (info->restore_data) {
-		if (restore_pipe_data(CR_FD_FIFO_DATA, fake_fifo, info->fe->id,
-				      info->bytes, info->off)) {
+	if (info->restore_data)
+		if (restore_pipe_data(CR_FD_FIFO_DATA, fake_fifo,
+					info->fe->pipe_id, pd_hash_fifo)) {
 			close(new_fifo);
 			new_fifo = -1;
 		}
-	}
 
 out:
 	close(fake_fifo);
@@ -121,44 +122,9 @@ static struct file_desc_ops fifo_desc_ops = {
 	.open		= open_fifo_fd,
 };
 
-static int handle_fifo_data(void)
-{
-	int img, ret;
-
-	img = open_image_ro(CR_FD_FIFO_DATA);
-	if (img < 0)
-		return -1;
-
-	while (1) {
-		struct pipe_data_entry pde;
-		struct fifo_info *info;
-
-		ret = read_img_eof(img, &pde);
-		if (ret <= 0)
-			break;
-
-		list_for_each_entry(info, &fifo_head, list) {
-			if (info->fe->pipe_id != pde.pipe_id ||
-			    info->restore_data)
-				continue;
-
-			info->off	= lseek(img, 0, SEEK_CUR) + pde.off;
-			info->bytes	= pde.bytes;
-
-			lseek(img, pde.bytes + pde.off, SEEK_CUR);
-
-			info->restore_data = true;
-			break;
-		}
-	}
-
-	close(img);
-	return ret;
-}
-
 int collect_fifo(void)
 {
-	struct fifo_info *info = NULL;
+	struct fifo_info *info = NULL, *f;
 	int img, ret;
 
 	img = open_image_ro(CR_FD_FIFO);
@@ -183,15 +149,21 @@ int collect_fifo(void)
 			info->fe->id, info->fe->pipe_id);
 
 		file_desc_add(&info->d, info->fe->id, &fifo_desc_ops);
-		list_add(&info->list, &fifo_head);
-	}
 
-	if (!ret)
-		ret = handle_fifo_data();
+		/* check who will restore the fifo data */
+		list_for_each_entry(f, &fifo_head, list)
+			if (f->fe->pipe_id == info->fe->pipe_id)
+				break;
+
+		if (&f->list == &fifo_head) {
+			list_add(&info->list, &fifo_head);
+			info->restore_data = true;
+		}
+	}
 
 	xfree(info ? info->fe : NULL);
 	xfree(info);
 	close(img);
 
-	return ret;
+	return collect_pipe_data(CR_FD_FIFO_DATA, pd_hash_fifo);
 }

include/pipes.h

@@ -14,6 +14,17 @@ struct pipe_data_dump {
 };
 
 extern int dump_one_pipe_data(struct pipe_data_dump *pd, int lfd, const struct fd_parms *p);
-extern int restore_pipe_data(int img_type, int pfd, u32 id, int bytes, off_t off);
+
+struct pipe_data_rst {
+	struct pipe_data_entry	pde;
+	struct pipe_data_rst	*next;
+};
+
+#define PIPE_DATA_HASH_BITS	5
+#define PIPE_DATA_HASH_SIZE	(1 << PIPE_DATA_HASH_BITS)
+#define PIPE_DATA_HASH_MASK	(PIPE_DATA_HASH_SIZE - 1)
+
+extern int collect_pipe_data(int img_type, struct pipe_data_rst **hash);
+extern int restore_pipe_data(int img_type, int pfd, u32 id, struct pipe_data_rst **hash);
 
 #endif

pipes.c

@@ -39,34 +39,37 @@ static void show_saved_pipe_fds(struct pipe_info *pi)
 		pr_info("   `- FD %d pid %d\n", fle->fe->fd, fle->pid);
 }
 
-static int handle_pipes_data(void)
+int collect_pipe_data(int img_type, struct pipe_data_rst **hash)
 {
 	int fd, ret;
 
-	fd = open_image_ro(CR_FD_PIPES_DATA);
+	fd = open_image_ro(img_type);
 	if (fd < 0)
 		return -1;
 
 	while (1) {
-		struct pipe_info *pi;
-		struct pipe_data_entry pde;
+		struct pipe_data_rst *r;
+		u32 off;
+
+		ret = -1;
+		r = xmalloc(sizeof(*r));
+		if (!r)
+			break;
 
-		ret = read_img_eof(fd, &pde);
+		ret = read_img_eof(fd, &r->pde);
 		if (ret <= 0)
 			break;
 
-		list_for_each_entry(pi, &pipes, list) {
-			if (pi->pe.pipe_id != pde.pipe_id)
-				continue;
-			if (!pi->create)
-				continue;
+		off = r->pde.off + lseek(fd, 0, SEEK_CUR);
+		lseek(fd, r->pde.bytes + r->pde.off, SEEK_CUR);
+		r->pde.off = off;
 
-			pi->off = lseek(fd, 0, SEEK_CUR) + pde.off;
-			pi->bytes = pde.bytes;
+		ret = r->pde.pipe_id & PIPE_DATA_HASH_MASK;
+		r->next = hash[ret];
+		hash[ret] = r;
 
-			lseek(fd, pde.bytes + pde.off, SEEK_CUR);
-			break;
-		}
+		pr_info("Collected pipe data for %#x (chain %u)\n",
+				r->pde.pipe_id, ret);
 	}
 
 	close(fd);
@@ -117,24 +120,33 @@ void mark_pipe_master(void)
 	}
 
 	list_splice(&head, &pipes);
-
-	handle_pipes_data();
 }
 
-int restore_pipe_data(int img_type, int pfd, u32 id, int bytes, off_t off)
+static struct pipe_data_rst *pd_hash_pipes[PIPE_DATA_HASH_SIZE];
+
+int restore_pipe_data(int img_type, int pfd, u32 id, struct pipe_data_rst **hash)
 {
 	int img, size = 0, ret;
+	struct pipe_data_rst *pd;
+
+	for (pd = hash[id & PIPE_DATA_HASH_MASK]; pd != NULL; pd = pd->next)
+		if (pd->pde.pipe_id == id)
+			break;
+
+	if (!pd) { /* no data for this pipe */
+		pr_info("No data for pipe %#x\n", id);
+		return 0;
+	}
 
 	img = open_image_ro(img_type);
 	if (img < 0)
 		return -1;
 
-	lseek(img, off, SEEK_SET);
-
-	pr_info("\t\tSplicing data size=%d off=%ld\n", bytes, off);
+	pr_info("\t\tSplicing data size=%u off=%u\n", pd->pde.bytes, pd->pde.off);
+	lseek(img, pd->pde.off, SEEK_SET);
 
-	while (size != bytes) {
-		ret = splice(img, NULL, pfd, NULL, bytes - size, 0);
+	while (size != pd->pde.bytes) {
+		ret = splice(img, NULL, pfd, NULL, pd->pde.bytes - size, 0);
 		if (ret < 0) {
 			pr_perror("%#x: Error splicing data", id);
 			goto err;
@@ -142,7 +154,7 @@ int restore_pipe_data(int img_type, int pfd, u32 id, int bytes, off_t off)
 
 		if (ret == 0) {
 			pr_err("%#x: Wanted to restore %d bytes, but got %d\n",
-			       id, bytes, size);
+			       id, pd->pde.bytes, size);
 			ret = -1;
 			goto err;
 		}
@@ -207,7 +219,8 @@ static int open_pipe(struct file_desc *d)
 		return -1;
 	}
 
-	ret = restore_pipe_data(CR_FD_PIPES_DATA, pfd[1], pi->pe.id, pi->bytes, pi->off);
+	ret = restore_pipe_data(CR_FD_PIPES_DATA, pfd[1],
+			pi->pe.pipe_id, pd_hash_pipes);
 	if (ret)
 		return -1;
 
@@ -295,7 +308,8 @@ int collect_pipes(void)
 	xfree(pi);
 
 	close(fd);
-	return ret;
+
+	return collect_pipe_data(CR_FD_PIPES_DATA, pd_hash_pipes);
 }
 
 int dump_one_pipe_data(struct pipe_data_dump *pd, int lfd, const struct fd_parms *p)