btrfs-progs: fix-data-checksum: introduce -m|--mirror option

This option allows "btrfs rescue fix-data-checksum" to use the specified
mirror number to update checksum item for all corrupted mirrors.

If the specified number is larger than the max number of mirrors, the
real mirror number will be `num % (num_mirrors + 1)`.

Signed-off-by: Qu Wenruo <wqu@suse.com>

Author: adam900710

Documentation/btrfs-rescue.rst

@@ -72,6 +72,12 @@ fix-data-checksum <device>
 	-i|--interactive
 		interactive mode, ask for how to repair, ignore the error by default
 
+	-m|--mirror <num>
+		use specified mirror to update the checksum item for all corrupted blocks.
+
+		The value must be >= 1, and if the corrupted block has less mirrors than
+		the value, the mirror number will be `num % (num_mirrors + 1)`.
+
 .. _man-rescue-clear-ino-cache:
 
 clear-ino-cache <device>

cmds/rescue-fix-data-checksum.c

@@ -381,7 +381,8 @@ static int update_csum_item(struct btrfs_fs_info *fs_info, u64 logical,
 }
 
 static void report_corrupted_blocks(struct btrfs_fs_info *fs_info,
-				    enum btrfs_fix_data_checksum_mode mode)
+				    enum btrfs_fix_data_checksum_mode mode,
+				    unsigned int mirror)
 {
 	struct corrupted_block *entry;
 	struct btrfs_path path = { 0 };
@@ -393,7 +394,6 @@ static void report_corrupted_blocks(struct btrfs_fs_info *fs_info,
 	}
 
 	list_for_each_entry(entry, &corrupted_blocks, list) {
-		unsigned int mirror;
 		bool has_printed = false;
 		int ret;
 
@@ -426,6 +426,10 @@ static void report_corrupted_blocks(struct btrfs_fs_info *fs_info,
 		case BTRFS_FIX_DATA_CSUMS_READONLY:
 			action = ACTION_IGNORE;
 			break;
+		case BTRFS_FIX_DATA_CSUMS_UPDATE_CSUM_ITEM:
+			action = ACTION_UPDATE_CSUM;
+			mirror = mirror % (entry->num_mirrors + 1);
+			break;
 		default:
 			UASSERT(0);
 		}
@@ -434,6 +438,7 @@ static void report_corrupted_blocks(struct btrfs_fs_info *fs_info,
 		case ACTION_IGNORE:
 			break;
 		case ACTION_UPDATE_CSUM:
+			UASSERT(mirror > 0 && mirror <= entry->num_mirrors);
 			ret = update_csum_item(fs_info, entry->logical, mirror);
 			break;
 		default:
@@ -455,7 +460,8 @@ static void free_corrupted_blocks(void)
 }
 
 int btrfs_recover_fix_data_checksum(const char *path,
-				    enum btrfs_fix_data_checksum_mode mode)
+				    enum btrfs_fix_data_checksum_mode mode,
+				    unsigned int mirror)
 {
 	struct btrfs_fs_info *fs_info;
 	struct btrfs_root *csum_root;
@@ -465,6 +471,8 @@ int btrfs_recover_fix_data_checksum(const char *path,
 	if (mode >= BTRFS_FIX_DATA_CSUMS_LAST)
 		return -EINVAL;
 
+	if (mode == BTRFS_FIX_DATA_CSUMS_UPDATE_CSUM_ITEM)
+		UASSERT(mirror > 0);
 	ret = check_mounted(path);
 	if (ret < 0) {
 		errno = -ret;
@@ -495,7 +503,7 @@ int btrfs_recover_fix_data_checksum(const char *path,
 		errno = -ret;
 		error("failed to iterate csum tree: %m");
 	}
-	report_corrupted_blocks(fs_info, mode);
+	report_corrupted_blocks(fs_info, mode, mirror);
 out_close:
 	free_corrupted_blocks();
 	close_ctree_fs_info(fs_info);

cmds/rescue.c

@@ -31,6 +31,7 @@
 #include "kernel-shared/extent_io.h"
 #include "kernel-shared/accessors.h"
 #include "kernel-shared/uapi/btrfs_tree.h"
+#include "common/string-utils.h"
 #include "common/messages.h"
 #include "common/utils.h"
 #include "common/help.h"
@@ -282,6 +283,7 @@ static const char * const cmd_rescue_fix_data_checksum_usage[] = {
 	"",
 	OPTLINE("-r|--readonly", "readonly mode, only report errors without repair"),
 	OPTLINE("-i|--interactive", "interactive mode, ignore the error by default."),
+	OPTLINE("-m|--mirror <mirror>", "update csum item using specified mirror"),
 	HELPINFO_INSERT_GLOBALS,
 	HELPINFO_INSERT_VERBOSE,
 	NULL
@@ -291,6 +293,7 @@ static int cmd_rescue_fix_data_checksum(const struct cmd_struct *cmd,
 					int argc, char **argv)
 {
 	enum btrfs_fix_data_checksum_mode mode = BTRFS_FIX_DATA_CSUMS_READONLY;
+	unsigned int mirror = 0;
 	int ret;
 	optind = 0;
 
@@ -300,9 +303,10 @@ static int cmd_rescue_fix_data_checksum(const struct cmd_struct *cmd,
 		static const struct option long_options [] = {
 			{"readonly", no_argument, NULL, 'r'},
 			{"interactive", no_argument, NULL, 'i'},
+			{"mirror", required_argument, NULL, 'm'},
 			{"NULL", 0, NULL, 0},
 		};
-		c = getopt_long(argc, argv, "ri", long_options, NULL);
+		c = getopt_long(argc, argv, "rim:", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
@@ -312,13 +316,21 @@ static int cmd_rescue_fix_data_checksum(const struct cmd_struct *cmd,
 		case 'i':
 			mode = BTRFS_FIX_DATA_CSUMS_INTERACTIVE;
 			break;
+		case 'm':
+			mode = BTRFS_FIX_DATA_CSUMS_UPDATE_CSUM_ITEM;
+			mirror = arg_strtou64(optarg);
+			if (mirror == 0) {
+				error("invalid mirror number %u, must be >= 1", mirror);
+				return 1;
+			}
+			break;
 		default:
 			usage_unknown_option(cmd, argv);
 		}
 	}
 	if (check_argc_min(argc - optind, 1))
 		return 1;
-	ret = btrfs_recover_fix_data_checksum(argv[optind], mode);
+	ret = btrfs_recover_fix_data_checksum(argv[optind], mode, mirror);
 	if (ret < 0) {
 		errno = -ret;
 		error("failed to fix data checksums: %m");

cmds/rescue.h

@@ -23,12 +23,14 @@
 enum btrfs_fix_data_checksum_mode {
 	BTRFS_FIX_DATA_CSUMS_READONLY,
 	BTRFS_FIX_DATA_CSUMS_INTERACTIVE,
+	BTRFS_FIX_DATA_CSUMS_UPDATE_CSUM_ITEM,
 	BTRFS_FIX_DATA_CSUMS_LAST,
 };
 
 int btrfs_recover_superblocks(const char *path, int yes);
 int btrfs_recover_chunk_tree(const char *path, int yes);
 int btrfs_recover_fix_data_checksum(const char *path,
-				    enum btrfs_fix_data_checksum_mode mode);
+				    enum btrfs_fix_data_checksum_mode mode,
+				    unsigned int mirror);
 
 #endif