btrfs-progs: fix-data-checksum: introduce interactive mode

This mode will ask user for how to fix each block.

User input can match the first letter or the whole action name to
specify given action, the input is verified case insensitive.

If no user input is provided, the default action is to ignore the
corrupted block.

If the input matches no action, a warning is outputted and user must
retry until a valid input is provided.

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

Author: adam900710

Documentation/btrfs-rescue.rst

@@ -69,6 +69,9 @@ fix-data-checksum <device>
 		readonly mode, only scan for and report data checksum mismatches,
 		do not repair
 
+	-i|--interactive
+		interactive mode, ask for how to repair, ignore the errors by default
+
 .. _man-rescue-clear-ino-cache:
 
 clear-ino-cache <device>

cmds/rescue-fix-data-checksum.c

@@ -15,6 +15,7 @@
  */
 
 #include "kerncompat.h"
+#include <ctype.h>
 #include "kernel-shared/disk-io.h"
 #include "kernel-shared/ctree.h"
 #include "kernel-shared/volumes.h"
@@ -45,6 +46,21 @@ struct corrupted_block {
 	unsigned long *error_mirror_bitmap;
 };
 
+enum fix_data_checksum_action_value {
+	ACTION_IGNORE,
+	ACTION_LAST,
+};
+
+static const struct fix_data_checksum_action {
+	enum fix_data_checksum_action_value value;
+	const char *string;
+} actions[] = {
+	[ACTION_IGNORE] = {
+		.value = ACTION_IGNORE,
+		.string = "ignore"
+	},
+};
+
 static int global_repair_mode;
 LIST_HEAD(corrupted_blocks);
 
@@ -243,10 +259,49 @@ static int iterate_csum_root(struct btrfs_fs_info *fs_info, struct btrfs_root *c
 	return ret;
 }
 
-static void report_corrupted_blocks(struct btrfs_fs_info *fs_info)
+#define ASK_ACTION_BUFSIZE	(32)
+static enum fix_data_checksum_action_value ask_action(void)
+{
+	char buf[ASK_ACTION_BUFSIZE] = { 0 };
+	bool printed;
+
+again:
+	printed = false;
+	for (int i = 0; i < ACTION_LAST; i++) {
+		if (printed)
+			pr_verbose(LOG_DEFAULT, "/");
+		/* Mark Ignore as default. */
+		if (i == ACTION_IGNORE)
+			pr_verbose(LOG_DEFAULT, "<<%c>>%s", toupper(actions[i].string[0]),
+				   actions[i].string + 1);
+		else
+			pr_verbose(LOG_DEFAULT, "<%c>%s", toupper(actions[i].string[0]),
+				   actions[i].string + 1);
+	}
+	pr_verbose(LOG_DEFAULT, ":");
+	fflush(stdout);
+	/* Default to Ignore if no action provided. */
+	if (fgets(buf, sizeof(buf) - 1, stdin) == 0)
+		return ACTION_IGNORE;
+	if (buf[0] == '\n')
+		return ACTION_IGNORE;
+	/* Check exact match or matching the initial letter. */
+	for (int i = 0; i < ACTION_LAST; i++) {
+		if (strncasecmp(buf, actions[i].string, 1) == 0 ||
+		    strncasecmp(buf, actions[i].string, ASK_ACTION_BUFSIZE) == 0)
+			return actions[i].value;
+	}
+	/* No valid action found, retry. */
+	warning("invalid action, please retry");
+	goto again;
+}
+
+static void report_corrupted_blocks(struct btrfs_fs_info *fs_info,
+				    enum btrfs_fix_data_checksum_mode mode)
 {
 	struct corrupted_block *entry;
 	struct btrfs_path path = { 0 };
+	enum fix_data_checksum_action_value action;
 
 	if (list_empty(&corrupted_blocks)) {
 		pr_verbose(LOG_DEFAULT, "no data checksum mismatch found\n");
@@ -279,6 +334,16 @@ static void report_corrupted_blocks(struct btrfs_fs_info *fs_info)
 			error("failed to iterate involved files: %m");
 			break;
 		}
+		switch (mode) {
+		case BTRFS_FIX_DATA_CSUMS_INTERACTIVE:
+			action = ask_action();
+			UASSERT(action == ACTION_IGNORE);
+			fallthrough;
+		case BTRFS_FIX_DATA_CSUMS_READONLY:
+			break;
+		default:
+			UASSERT(0);
+		}
 	}
 }
 
@@ -334,7 +399,7 @@ int btrfs_recover_fix_data_checksum(const char *path, enum btrfs_fix_data_checks
 		errno = -ret;
 		error("failed to iterate csum tree: %m");
 	}
-	report_corrupted_blocks(fs_info);
+	report_corrupted_blocks(fs_info, mode);
 out_close:
 	free_corrupted_blocks();
 	close_ctree_fs_info(fs_info);

cmds/rescue.c

@@ -280,7 +280,8 @@ static const char * const cmd_rescue_fix_data_checksum_usage[] = {
 	"btrfs rescue fix-data-checksum <device>",
 	"Fix data checksum mismatches.",
 	"",
-	OPTLINE("-r", "readonly mode, only report errors without repair"),
+	OPTLINE("-r|--readonly", "readonly mode, only report errors without repair"),
+	OPTLINE("-i|--interactive", "interactive mode, ignore the error by default."),
 	HELPINFO_INSERT_GLOBALS,
 	HELPINFO_INSERT_VERBOSE,
 	NULL
@@ -298,16 +299,20 @@ static int cmd_rescue_fix_data_checksum(const struct cmd_struct *cmd,
 		enum { GETOPT_VAL_DRYRUN = GETOPT_VAL_FIRST };
 		static const struct option long_options [] = {
 			{"readonly", no_argument, NULL, 'r'},
+			{"interactive", no_argument, NULL, 'i'},
 			{"NULL", 0, NULL, 0},
 		};
 
-		c = getopt_long(argc, argv, "r", long_options, NULL);
+		c = getopt_long(argc, argv, "ri", long_options, NULL);
 		if (c < 0)
 			break;
 		switch (c) {
 		case 'r':
 			mode = BTRFS_FIX_DATA_CSUMS_READONLY;
 			break;
+		case 'i':
+			mode = BTRFS_FIX_DATA_CSUMS_INTERACTIVE;
+			break;
 		default:
 			usage_unknown_option(cmd, argv);
 		}

cmds/rescue.h

@@ -22,6 +22,7 @@
 
 enum btrfs_fix_data_checksum_mode {
 	BTRFS_FIX_DATA_CSUMS_READONLY,
+	BTRFS_FIX_DATA_CSUMS_INTERACTIVE,
 	BTRFS_FIX_DATA_CSUMS_LAST,
 };