[v6] btrfs-progs: dump-tree: add noscan option

Commit Message

Anand Jain May 16, 2019, 2:10 a.m. UTC

From: Anand Jain <[e-mail]>

The cli 'btrfs inspect dump-tree <dev>' will scan for the partner devices
if any by default.

So as of now you can not inspect each mirrored device independently.

This patch adds noscan option, which when used won't scan the system for
the partner devices, instead it just uses the devices provided in the
argument.

For example:
  btrfs inspect dump-tree --noscan <dev> [<dev>..]

This helps to debug degraded raid1 and raid10.

Signed-off-by: Anand Jain <[e-mail]>
---
v5->v6: rebase on latest btrfs-progs::devel
v4->v5: nit: use %m to print error string.
	changelog update.
v3->v4: change the patch title.
	collapse scan_args() to its only parent cmd_inspect_dump_tree()
	(it was bit confusing).
	update the change log.
	update usage.
	update man page.
v2->v3: make it scalable for more than two disks in noscan mode
v1->v2: rename --degraded to --noscan

 Documentation/btrfs-inspect-internal.asciidoc |  5 +-
 cmds-inspect-dump-tree.c                      | 53 ++++++++++++++-----
 2 files changed, 45 insertions(+), 13 deletions(-)

Patch

diff --git a/Documentation/btrfs-inspect-internal.asciidoc b/Documentation/btrfs-inspect-internal.asciidoc
index 210f18c30a40..c9962ab3b548 100644
--- a/Documentation/btrfs-inspect-internal.asciidoc
+++ b/Documentation/btrfs-inspect-internal.asciidoc
@@ -61,7 +61,7 @@  specify which mirror to print, valid values are 0, 1 and 2 and the superblock
 must be present on the device with a valid signature, can be used together with
 '--force'
 
-*dump-tree* [options] <device>::
+*dump-tree* [options] <device> [device...]::
 (replaces the standalone tool *btrfs-debug-tree*)
 +
 Dump tree structures from a given device in textual form, expand keys to human
@@ -95,6 +95,9 @@  intermixed in the output
 --bfs::::
 use breadth-first search to print trees. the nodes are printed before all
 leaves
+--device::::
+do not scan the system for other partner device(s), only use the device(s)
+provided in the argument
 -t <tree_id>::::
 print only the tree with the specified ID, where the ID can be numerical or
 common name in a flexible human readable form
diff --git a/cmds-inspect-dump-tree.c b/cmds-inspect-dump-tree.c
index b41d2e111955..af5a6611285d 100644
--- a/cmds-inspect-dump-tree.c
+++ b/cmds-inspect-dump-tree.c
@@ -21,6 +21,7 @@ 
 #include <unistd.h>
 #include <uuid/uuid.h>
 #include <getopt.h>
+#include <fcntl.h>
 
 #include "kerncompat.h"
 #include "radix-tree.h"
@@ -185,7 +186,7 @@  static u64 treeid_from_string(const char *str, const char **end)
 }
 
 const char * const cmd_inspect_dump_tree_usage[] = {
-	"btrfs inspect-internal dump-tree [options] device",
+	"btrfs inspect-internal dump-tree [options] <device> [<device> ..]",
 	"Dump tree structures from a given device",
 	"Dump tree structures from a given device in textual form, expand keys to human",
 	"readable equivalents where possible.",
@@ -201,6 +202,7 @@  const char * const cmd_inspect_dump_tree_usage[] = {
 	"                       can be specified multiple times",
 	"-t|--tree <tree_id>    print only tree with the given id (string or number)",
 	"--follow               use with -b, to show all children tree blocks of <block_num>",
+	"--noscan               do not scan for the partner device(s)",
 	NULL
 };
 
@@ -296,7 +298,7 @@  int cmd_inspect_dump_tree(int argc, char **argv)
 	struct btrfs_key found_key;
 	struct cache_tree block_root;	/* for multiple --block parameters */
 	char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
-	int ret;
+	int ret = 0;
 	int slot;
 	int extent_only = 0;
 	int device_only = 0;
@@ -304,6 +306,7 @@  int cmd_inspect_dump_tree(int argc, char **argv)
 	int roots_only = 0;
 	int root_backups = 0;
 	int traverse = BTRFS_PRINT_TREE_DEFAULT;
+	int dev_optind;
 	unsigned open_ctree_flags;
 	u64 block_bytenr;
 	struct btrfs_root *tree_root_scan;
@@ -322,8 +325,8 @@  int cmd_inspect_dump_tree(int argc, char **argv)
 	optind = 0;
 	while (1) {
 		int c;
-		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS,
-		       GETOPT_VAL_BFS };
+		enum { GETOPT_VAL_FOLLOW = 256, GETOPT_VAL_DFS, GETOPT_VAL_BFS,
+		       GETOPT_VAL_NOSCAN};
 		static const struct option long_options[] = {
 			{ "extents", no_argument, NULL, 'e'},
 			{ "device", no_argument, NULL, 'd'},
@@ -335,6 +338,7 @@  int cmd_inspect_dump_tree(int argc, char **argv)
 			{ "follow", no_argument, NULL, GETOPT_VAL_FOLLOW },
 			{ "bfs", no_argument, NULL, GETOPT_VAL_BFS },
 			{ "dfs", no_argument, NULL, GETOPT_VAL_DFS },
+			{ "noscan", no_argument, NULL, GETOPT_VAL_NOSCAN },
 			{ NULL, 0, NULL, 0 }
 		};
 
@@ -399,24 +403,49 @@  int cmd_inspect_dump_tree(int argc, char **argv)
 		case GETOPT_VAL_BFS:
 			traverse = BTRFS_PRINT_TREE_BFS;
 			break;
+		case GETOPT_VAL_NOSCAN:
+			open_ctree_flags |= OPEN_CTREE_NO_DEVICES;
+			break;
 		default:
 			usage_unknown_option(cmd_inspect_dump_tree_usage, argv);
 		}
 	}
 
-	if (check_argc_exact(argc - optind, 1))
+	if (check_argc_min(argc - optind, 1))
 		return 1;
 
-	ret = check_arg_type(argv[optind]);
-	if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
+	dev_optind = optind;
+	while (dev_optind < argc) {
+		int fd;
+		struct btrfs_fs_devices *fs_devices;
+		u64 num_devices;
+
+		ret = check_arg_type(argv[optind]);
+		if (ret != BTRFS_ARG_BLKDEV && ret != BTRFS_ARG_REG) {
+			if (ret < 0) {
+				errno = -ret;
+				error("invalid argument %s: %m", argv[dev_optind]);
+			} else {
+				error("not a block device or regular file: %s",
+				       argv[dev_optind]);
+			}
+		}
+		fd = open(argv[dev_optind], O_RDONLY);
+		if (fd < 0) {
+			error("cannot open %s: %m", argv[dev_optind]);
+			return -EINVAL;
+		}
+		ret = btrfs_scan_one_device(fd, argv[dev_optind], &fs_devices,
+					    &num_devices,
+					    BTRFS_SUPER_INFO_OFFSET,
+					    SBREAD_DEFAULT);
+		close(fd);
 		if (ret < 0) {
 			errno = -ret;
-			error("invalid argument %s: %m", argv[optind]);
-		} else {
-			error("not a block device or regular file: %s",
-			      argv[optind]);
+			error("device scan %s: %m", argv[dev_optind]);
+			return ret;
 		}
-		goto out;
+		dev_optind++;
 	}
 
 	printf("%s\n", PACKAGE_STRING);