btrfs-progs: move inode cache removal to rescue group

The option "--clear-ino-cache" is not really that suitable for "btrfs
check" group.

Let's move it to "btrfs rescue" group to fix those small hiccups, just
like the existing "btrfs rescue fix-device-size" command.

For now, "btrfs check --clear-ino-cache" would still work, with one
extra warning referring to "btrfs rescue clear-ino-cache".
This is mostly to reduce the surprise, and keep script users (I doubt if
there is any though) happy for now.

In the next or two releases, we would fully remove the support in "btrfs
check" group.

Another small change is, in the documents, we refer to the feature as
"inode map", which doesn't match with the mount option documents.
Since we're here, unify them to "inode cache" feature.

Issue: #669
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Documentation/btrfs-check.rst

@@ -84,8 +84,11 @@ SAFE OR ADVISORY OPTIONS
         See also the *clear_cache* mount option.
 
 --clear-ino-cache
-        remove leftover items pertaining to the deprecated inode map feature
+        remove leftover items pertaining to the deprecated `inode cache` feature
 
+	.. warning::
+		This option is deprecated, please use `btrfs rescue clear-ino-cache`
+		instead, this option would be removed in the future eventually.
 
 DANGEROUS OPTIONS
 -----------------

Documentation/btrfs-rescue.rst

@@ -50,6 +50,12 @@ fix-device-size <device>
 
                 WARNING: CPU: 3 PID: 439 at fs/btrfs/ctree.h:1559 btrfs_update_device+0x1c5/0x1d0 [btrfs]
 
+clear-ino-cache <device>
+        Remove leftover items pertaining to the deprecated `inode cache` feature.
+
+	The `inode cache` feature (enabled by mount option "inode_cache") has been
+	completely removed in 5.11 kernel.
+
 clear-uuid-tree <device>
         Clear UUID tree, so that kernel can re-generate it at next read-write
         mount.

check/main.c

@@ -10242,6 +10242,7 @@ static int cmd_check(const struct cmd_struct *cmd, int argc, char **argv)
 	}
 
 	if (clear_ino_cache) {
+		warning("--clear-ino-cache option is deprecated, please use \"btrfs rescue clear-ino-cache\" instead");
 		ret = clear_ino_cache_items(gfs_info);
 		err = ret;
 		goto close_out;

cmds/rescue.c

@@ -34,6 +34,7 @@
 #include "common/utils.h"
 #include "common/help.h"
 #include "common/open-utils.h"
+#include "common/clear-cache.h"
 #include "cmds/commands.h"
 #include "cmds/rescue.h"
 
@@ -405,6 +406,56 @@ out:
 }
 static DEFINE_SIMPLE_COMMAND(rescue_clear_uuid_tree, "clear-uuid-tree");
 
+static const char * const cmd_rescue_clear_ino_cache_usage[] = {
+	"btrfs rescue clear-ino-cache <device>",
+	"remove leftover items pertaining to the deprecated inode cache feature",
+	NULL
+};
+
+static int cmd_rescue_clear_ino_cache(const struct cmd_struct *cmd,
+				      int argc, char **argv)
+{
+	struct open_ctree_args oca = { 0 };
+	struct btrfs_fs_info *fs_info;
+	char *devname;
+	int ret;
+
+	clean_args_no_options(cmd, argc, argv);
+
+	if (check_argc_exact(argc, 2))
+		return 1;
+
+	devname = argv[optind];
+	ret = check_mounted(devname);
+	if (ret < 0) {
+		errno = -ret;
+		error("could not check mount status: %m");
+		goto out;
+	} else if (ret) {
+		error("%s is currently mounted", devname);
+		ret = -EBUSY;
+		goto out;
+	}
+	oca.filename = devname;
+	oca.flags = OPEN_CTREE_WRITES;
+	fs_info = open_ctree_fs_info(&oca);
+	if (!fs_info) {
+		error("could not open btrfs");
+		ret = -EIO;
+		goto out;
+	}
+	ret = clear_ino_cache_items(fs_info);
+	if (ret < 0) {
+		errno = -ret;
+		error("failed to clear ino cache: %m");
+	} else {
+		pr_verbose(LOG_DEFAULT, "Successfully cleared ino cache");
+	}
+out:
+	return !!ret;
+}
+static DEFINE_SIMPLE_COMMAND(rescue_clear_ino_cache, "clear-ino-cache");
+
 static const char rescue_cmd_group_info[] =
 "toolbox for specific rescue operations";
 
@@ -415,6 +466,7 @@ static const struct cmd_group rescue_cmd_group = {
 		&cmd_struct_rescue_zero_log,
 		&cmd_struct_rescue_fix_device_size,
 		&cmd_struct_rescue_create_control_device,
+		&cmd_struct_rescue_clear_ino_cache,
 		&cmd_struct_rescue_clear_uuid_tree,
 		NULL
 	}