btrfs-progs: check: Add --readonly flag

Particularly during support conversations, people get confused about
which options to use with btrfs check. Adding a flag, --readonly, which
implies the default read-only behaviour and which conflicts with the
read-write operations, should help make the behaviour of the tool clear.

Signed-off-by: Hugo Mills <hugo@carfax.org.uk>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/cmds-check.c b/cmds-check.c
index c24e4e04ee38e009b6ecbb2e8f3caea7d2d0f4ef..68863707a30109f9f60c6c2452fc93287d2a644a 100644 (file)
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -8429,6 +8429,7 @@ int cmd_check(int argc, char **argv)
        int ret;
        u64 num;
        int init_csum_tree = 0;
+       int readonly = 0;
        int qgroup_report = 0;
        enum btrfs_open_ctree_flags ctree_flags = OPEN_CTREE_EXCLUSIVE;
 
@@ -8436,10 +8437,11 @@ int cmd_check(int argc, char **argv)
                int c;
                int option_index = 0;
                enum { OPT_REPAIR = 257, OPT_INIT_CSUM, OPT_INIT_EXTENT,
-                       OPT_CHECK_CSUM };
+                       OPT_CHECK_CSUM, OPT_READONLY };
                static const struct option long_options[] = {
                        { "super", 1, NULL, 's' },
                        { "repair", 0, NULL, OPT_REPAIR },
+                       { "readonly", 0, NULL, OPT_READONLY },
                        { "init-csum-tree", 0, NULL, OPT_INIT_CSUM },
                        { "init-extent-tree", 0, NULL, OPT_INIT_EXTENT },
                        { "check-data-csum", 0, NULL, OPT_CHECK_CSUM },
@@ -8488,6 +8490,9 @@ int cmd_check(int argc, char **argv)
                                repair = 1;
                                ctree_flags |= OPEN_CTREE_WRITES;
                                break;
+                       case OPT_READONLY:
+                               readonly = 1;
+                               break;
                        case OPT_INIT_CSUM:
                                printf("Creating a new CRC tree\n");
                                init_csum_tree = 1;
@@ -8510,6 +8515,12 @@ int cmd_check(int argc, char **argv)
        if (check_argc_exact(argc, 1))
                usage(cmd_check_usage);
 
+       /* This check is the only reason for --readonly to exist */
+       if (readonly && repair) {
+               fprintf(stderr, "Repair options are not compatible with --readonly\n");
+               exit(1);
+       }
+
        radix_tree_init();
        cache_tree_init(&root_cache);