btrfs-progs: implement btrfs check --clear-space-cache v2

Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
[ adjusted error messages ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/Documentation/btrfs-check.asciidoc b/Documentation/btrfs-check.asciidoc
index 5ef414e..633cbbf 100644 (file)
--- a/Documentation/btrfs-check.asciidoc
+++ b/Documentation/btrfs-check.asciidoc
@@ -80,12 +80,16 @@ superblock is damaged.
 
 --clear-space-cache v1|v2::
 completely wipe all free space cache of given type
-
-NOTE: Only v1 free space cache supported is implemented.
 +
-Kernel mount option 'clear_cache' is only designed to rebuild free space cache
-which is modified during the lifetime of that mount option.  It doesn't rebuild
-all free space cache, nor clear them out.
+For free space cache 'v1', the 'clear_cache' kernel mount option only rebuilds
+the free space cache for block groups that are modified while the filesystem is
+mounted with that option. Thus, using this option with 'v1' makes it possible
+to actually clear the entire free space cache.
++
+For free space cache 'v2', the 'clear_cache' kernel mount option does destroy
+the entire free space cache. This option with 'v2' provides an alternative
+method of clearing the free space cache that doesn't require mounting the
+filesystem.
 
 
 DANGEROUS OPTIONS

diff --git a/cmds-check.c b/cmds-check.c
index e28ad2f..9f77e94 100644 (file)
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -11175,7 +11175,6 @@ const char * const cmd_check_usage[] = {
        "--chunk-root <bytenr>       use the given bytenr for the chunk tree root",
        "-p|--progress               indicate progress",
        "--clear-space-cache v1|v2   clear space cache for v1 or v2",
-       "                            NOTE: v1 support implemented",
        NULL
 };
 
@@ -11297,13 +11296,16 @@ int cmd_check(int argc, char **argv)
                                }
                                break;
                        case GETOPT_VAL_CLEAR_SPACE_CACHE:
-                               if (strcmp(optarg, "v1") != 0) {
+                               if (strcmp(optarg, "v1") == 0) {
+                                       clear_space_cache = 1;
+                               } else if (strcmp(optarg, "v2") == 0) {
+                                       clear_space_cache = 2;
+                                       ctree_flags |= OPEN_CTREE_INVALIDATE_FST;
+                               } else {
                                        error(
-                       "only v1 support implmented, unrecognized value %s",
-                       optarg);
+               "invalid argument to --clear-space-cache, must be v1 or v2");
                                        exit(1);
                                }
-                               clear_space_cache = 1;
                                ctree_flags |= OPEN_CTREE_WRITES;
                                break;
                }
@@ -11357,11 +11359,11 @@ int cmd_check(int argc, char **argv)
 
        global_info = info;
        root = info->fs_root;
-       if (clear_space_cache) {
+       if (clear_space_cache == 1) {
                if (btrfs_fs_compat_ro(info,
                                BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE)) {
                        error(
-                       "free space cache v2 detected, clearing not implemented");
+               "free space cache v2 detected, use --clear-space-cache v2");
                        ret = 1;
                        goto close_out;
                }
@@ -11374,6 +11376,22 @@ int cmd_check(int argc, char **argv)
                        printf("Free space cache cleared\n");
                }
                goto close_out;
+       } else if (clear_space_cache == 2) {
+               if (!btrfs_fs_compat_ro(info,
+                                       BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE)) {
+                       printf("no free space cache v2 to clear\n");
+                       ret = 0;
+                       goto close_out;
+               }
+               printf("Clear free space cache v2\n");
+               ret = btrfs_clear_free_space_tree(info);
+               if (ret) {
+                       error("failed to clear free space cache v2: %d", ret);
+                       ret = 1;
+               } else {
+                       printf("free space cache v2 cleared\n");
+               }
+               goto close_out;
        }
 
        /*