btrfs-progs: mkfs: add --inode-flags option

This new option allows end users to specify certain per-inode flags for
specified file/directory inside rootdir.

And mkfs will follow the kernel behavior by inheriting the inode flag
from the parent.

For example:

 rootdir
 |- file1
 |- file2
 |- dir1/
 |  |- file3
 |- subv/     << will be created as a subvolume using --subvol option
    |- dir2/
    |  |- file4
    |- file5

When `mkfs.btrfs --rootdir rootdir --subvol subv --inode-flags
nodatacow:dir1 --inode-flags nodatacow:subv", then the following files
and directory will have *nodatacow* flag set:

- dir1
- file3
- subv
- dir2
- file4
- file5

For now only two flags are supported:

- nodatacow
  Disable data COW, implies *nodatasum* for regular files

- nodatasum
  Disable data checksum only.

This also works with --compress option, and files with nodatasum or
nodatacow flag will skip compression.

Signed-off-by: Qu Wenruo <[email protected]>

Author: adam900710

Documentation/mkfs.btrfs.rst

@@ -213,6 +213,41 @@ OPTIONS
         :file:`hardlink1` and :file:`hardlink2` because :file:`hardlink3` will
         be inside a new subvolume.
 
+--inode-flags <flags>:<path>
+	Specify that *path* to have inode *flags*, other than the default one (which
+	implies data CoW and data checksum).  The option *--rootdir* must also be
+	specified.  This option can be speicified multiple times.
+
+	The supported flag(s) are:
+
+	* *nodatacow*: disable data CoW, implies *nodatasum* for regular files.
+	* *nodatasum*: disable data checksum only.
+
+	*flags* can be separated by comma (',').
+
+	Children inodes will inherit the flags from their parent inodes, like the
+	following case:
+
+        .. code-block:: none
+
+		rootdir/
+		|- file1
+		|- file2
+		|- dir/
+		   |- file3
+
+	In that case, if *--inode-flags nodatacow:dir* is specified, both
+	:file:`dir` and :file:`file3` will have the *nodatacow* flag.
+
+	And this option also works with *--subvol* option, but the inode flag of
+	each subvolume is independent and will not inherit from the parent directory.
+	(The same as the kernel behavior)
+
+        .. note::
+                Both *--inode-flags* and *--subvol* options are memory hungry,
+		will consume at least 8KiB for each option.
+		Please keep the usage of both options to minimal.
+
 --shrink
         Shrink the filesystem to its minimal size, only works with *--rootdir* option.
 

mkfs/main.c

@@ -1164,6 +1164,63 @@ static int parse_subvolume(const char *path, struct list_head *subvols,
 	return 0;
 }
 
+static int parse_inode_flags(const char *option, struct list_head *inode_flags_list)
+{
+	struct rootdir_inode_flags_entry *entry = NULL;
+	char *colon;
+	char *dumpped = NULL;
+	char *token;
+	int ret;
+
+	dumpped = strdup(option);
+	if (!dumpped) {
+		ret = -ENOMEM;
+		error_msg(ERROR_MSG_MEMORY, NULL);
+		goto cleanup;
+	}
+	entry = calloc(1, sizeof(*entry));
+	if (!entry) {
+		ret = -ENOMEM;
+		error_msg(ERROR_MSG_MEMORY, NULL);
+		goto cleanup;
+	}
+	colon = strstr(dumpped, ":");
+	if (!colon) {
+		error("invalid option: %s", option);
+		ret = -EINVAL;
+		goto cleanup;
+	}
+	*colon = '\0';
+
+	token = strtok(dumpped, ",");
+	while (token) {
+		if (token == NULL)
+			break;
+		if (strcmp(token, "nodatacow") == 0) {
+			entry->nodatacow = true;
+		} else if (strcmp(token, "nodatasum") == 0) {
+			entry->nodatasum = true;
+		} else {
+			error("unknown flag: %s", token);
+			ret = -EINVAL;
+			goto cleanup;
+		}
+		token = strtok(NULL, ",");
+	}
+
+	if (arg_copy_path(entry->inode_path, colon + 1, sizeof(entry->inode_path))) {
+		error("--inode-flags path too long");
+		ret = -E2BIG;
+		goto cleanup;
+	}
+	list_add_tail(&entry->list, inode_flags_list);
+	return 0;
+cleanup:
+	free(dumpped);
+	free(entry);
+	return ret;
+}
+
 int BOX_MAIN(mkfs)(int argc, char **argv)
 {
 	char *file;
@@ -1206,10 +1263,12 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 	int nr_global_roots = sysconf(_SC_NPROCESSORS_ONLN);
 	char *source_dir = NULL;
 	struct rootdir_subvol *rds;
+	struct rootdir_inode_flags_entry *rif;
 	bool has_default_subvol = false;
 	enum btrfs_compression_type compression = BTRFS_COMPRESS_NONE;
 	unsigned int compression_level = 0;
 	LIST_HEAD(subvols);
+	LIST_HEAD(inode_flags_list);
 
 	cpu_detect_flags();
 	hash_init_accel();
@@ -1223,6 +1282,7 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 			GETOPT_VAL_CHECKSUM,
 			GETOPT_VAL_GLOBAL_ROOTS,
 			GETOPT_VAL_DEVICE_UUID,
+			GETOPT_VAL_INODE_FLAGS,
 			GETOPT_VAL_COMPRESS,
 		};
 		static const struct option long_options[] = {
@@ -1241,6 +1301,7 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 			{ "version", no_argument, NULL, 'V' },
 			{ "rootdir", required_argument, NULL, 'r' },
 			{ "subvol", required_argument, NULL, 'u' },
+			{ "inode-flags", required_argument, NULL, GETOPT_VAL_INODE_FLAGS },
 			{ "nodiscard", no_argument, NULL, 'K' },
 			{ "features", required_argument, NULL, 'O' },
 			{ "runtime-features", required_argument, NULL, 'R' },
@@ -1374,6 +1435,11 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 			case 'q':
 				bconf_be_quiet();
 				break;
+			case GETOPT_VAL_INODE_FLAGS:
+				ret = parse_inode_flags(optarg, &inode_flags_list);
+				if (ret)
+					goto error;
+				break;
 			case GETOPT_VAL_COMPRESS:
 				if (parse_compression(optarg, &compression, &compression_level)) {
 					ret = 1;
@@ -1438,6 +1504,11 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 		ret = 1;
 		goto error;
 	}
+	if (!list_empty(&inode_flags_list) && source_dir == NULL) {
+		error("option --inode-flags must be used with --rootdir");
+		ret = 1;
+		goto error;
+	}
 
 	if (source_dir) {
 		char *canonical = realpath(source_dir, NULL);
@@ -1503,6 +1574,41 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 		}
 	}
 
+	list_for_each_entry(rif, &inode_flags_list, list) {
+		char path[PATH_MAX];
+		struct rootdir_inode_flags_entry *rif2;
+
+		if (path_cat_out(path, source_dir, rif->inode_path)) {
+			ret = -EINVAL;
+			error("path invalid: %s", path);
+			goto error;
+		}
+		if (!realpath(path, rif->full_path)) {
+			ret = -errno;
+			error("could not get canonical path: %s: %m", path);
+			goto error;
+		}
+		if (!path_exists(rif->full_path)) {
+			ret = -ENOENT;
+			error("inode path does not exist: %s", rif->full_path);
+			goto error;
+		}
+		list_for_each_entry(rif2, &inode_flags_list, list) {
+			/*
+			 * Only compare entryies before us. So we won't compare
+			 * the same pair twice.
+			 */
+			if (rif2 == rif)
+				break;
+			if (strcmp(rif2->full_path, rif->full_path) == 0) {
+				error("duplicated inode flag entries for %s",
+					rif->full_path);
+				ret = -EEXIST;
+				goto error;
+			}
+		}
+	}
+
 	if (*fs_uuid) {
 		uuid_t dummy_uuid;
 
@@ -2084,9 +2190,15 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 				   rds->is_default ? "" : " ",
 				   rds->dir);
 		}
+		list_for_each_entry(rif, &inode_flags_list, list) {
+			pr_verbose(LOG_DEFAULT, "  Inode flags (%s):  %s\n",
+				   rif->nodatacow ? "NODATACOW" : "",
+				   rif->inode_path);
+		}
 
 		ret = btrfs_mkfs_fill_dir(trans, source_dir, root,
-					  &subvols, compression,
+					  &subvols, &inode_flags_list,
+					  compression,
 					  compression_level);
 		if (ret) {
 			errno = -ret;
@@ -2229,6 +2341,12 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 		list_del(&head->list);
 		free(head);
 	}
+	while (!list_empty(&inode_flags_list)) {
+		rif = list_entry(inode_flags_list.next,
+				 struct rootdir_inode_flags_entry, list);
+		list_del(&rif->list);
+		free(rif);
+	}
 
 	return !!ret;
 

mkfs/rootdir.c

@@ -153,6 +153,7 @@ static struct rootdir_path current_path = {
 
 static struct btrfs_trans_handle *g_trans = NULL;
 static struct list_head *g_subvols;
+static struct list_head *g_inode_flags_list;
 static u64 next_subvol_id = BTRFS_FIRST_FREE_OBJECTID;
 static u64 default_subvol_id;
 static enum btrfs_compression_type g_compression;
@@ -1296,6 +1297,40 @@ static u8 ftype_to_btrfs_type(mode_t ftype)
 	return BTRFS_FT_UNKNOWN;
 }
 
+static void update_inode_flags(const struct rootdir_inode_flags_entry *rif,
+			       struct btrfs_inode_item *stack_inode)
+{
+	u64 inode_flags;
+
+	inode_flags = btrfs_stack_inode_flags(stack_inode);
+	if (rif->nodatacow) {
+		inode_flags |= BTRFS_INODE_NODATACOW;
+
+		if (S_ISREG(btrfs_stack_inode_mode(stack_inode)))
+			inode_flags |= BTRFS_INODE_NODATASUM;
+	}
+	if (rif->nodatasum)
+		inode_flags |= BTRFS_INODE_NODATASUM;
+
+	btrfs_set_stack_inode_flags(stack_inode, inode_flags);
+}
+
+static void search_and_update_inode_flags(struct btrfs_inode_item *stack_inode,
+					 const char *full_path)
+{
+	struct rootdir_inode_flags_entry *rif;
+
+	list_for_each_entry(rif, g_inode_flags_list, list) {
+		if (strcmp(rif->full_path, full_path) == 0) {
+			update_inode_flags(rif, stack_inode);
+
+			list_del(&rif->list);
+			free(rif);
+			return;
+		}
+	}
+}
+
 static int ftw_add_subvol(const char *full_path, const struct stat *st,
 			  int typeflag, struct FTW *ftwbuf,
 			  struct rootdir_subvol *subvol)
@@ -1354,6 +1389,7 @@ static int ftw_add_subvol(const char *full_path, const struct stat *st,
 	}
 	stat_to_inode_item(&inode_item, st);
 
+	search_and_update_inode_flags(&inode_item, full_path);
 	btrfs_set_stack_inode_nlink(&inode_item, 1);
 	ret = update_inode_item(g_trans, new_root, &inode_item, ino);
 	if (ret < 0) {
@@ -1373,6 +1409,31 @@ static int ftw_add_subvol(const char *full_path, const struct stat *st,
 	return 0;
 }
 
+static int read_inode_item(struct btrfs_root *root, struct btrfs_inode_item *inode_item,
+			   u64 ino)
+{
+	struct btrfs_path path = { 0 };
+	struct btrfs_key key;
+	int ret;
+
+	key.objectid = ino;
+	key.type = BTRFS_INODE_ITEM_KEY;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+	if (ret > 0)
+		ret = -ENOENT;
+	if (ret < 0)
+		goto out;
+
+	read_extent_buffer(path.nodes[0], inode_item,
+			   btrfs_item_ptr_offset(path.nodes[0], path.slots[0]),
+			   sizeof(*inode_item));
+out:
+	btrfs_release_path(&path);
+	return ret;
+}
+
 static int ftw_add_inode(const char *full_path, const struct stat *st,
 			 int typeflag, struct FTW *ftwbuf)
 {
@@ -1520,6 +1581,7 @@ static int ftw_add_inode(const char *full_path, const struct stat *st,
 		return ret;
 	}
 	stat_to_inode_item(&inode_item, st);
+	search_and_update_inode_flags(&inode_item, full_path);
 
 	ret = btrfs_insert_inode(g_trans, root, ino, &inode_item);
 	if (ret < 0) {
@@ -1552,11 +1614,17 @@ static int ftw_add_inode(const char *full_path, const struct stat *st,
 	}
 
 	/*
-	 * btrfs_add_link() has increased the nlink to 1 in the metadata.
-	 * Also update the value in case we need to update the inode item
-	 * later.
+	 * btrfs_add_link() has increased the nlink, and may even updated the
+	 * inode flags (inheritted from the parent).
+	 * Read out the latest version of inode item.
 	 */
-	btrfs_set_stack_inode_nlink(&inode_item, 1);
+	ret = read_inode_item(root, &inode_item, ino);
+	if (ret < 0) {
+		errno = -ret;
+		error("failed to read inode item for subvol %llu inode %llu ('%s'): %m",
+			btrfs_root_id(root), ino, full_path);
+		return ret;
+	}
 
 	ret = add_xattr_item(g_trans, root, ino, full_path);
 	if (ret < 0) {
@@ -1649,6 +1717,7 @@ static int set_default_subvolume(struct btrfs_trans_handle *trans)
 
 int btrfs_mkfs_fill_dir(struct btrfs_trans_handle *trans, const char *source_dir,
 			struct btrfs_root *root, struct list_head *subvols,
+			struct list_head *inode_flags_list,
 			enum btrfs_compression_type compression,
 			unsigned int compression_level)
 {
@@ -1695,6 +1764,7 @@ int btrfs_mkfs_fill_dir(struct btrfs_trans_handle *trans, const char *source_dir
 
 	g_trans = trans;
 	g_subvols = subvols;
+	g_inode_flags_list = inode_flags_list;
 	g_compression = compression;
 	g_compression_level = compression_level;
 	INIT_LIST_HEAD(&current_path.inode_list);

mkfs/rootdir.h

@@ -45,8 +45,23 @@ struct rootdir_subvol {
 	bool readonly;
 };
 
+/*
+ * Represent a flag for specified inode at @full_path.
+ */
+struct rootdir_inode_flags_entry {
+	struct list_head list;
+	/* Fully canonicalized path to the source file. */
+	char full_path[PATH_MAX];
+	/* Path inside the source directory. */
+	char inode_path[PATH_MAX];
+
+	bool nodatacow;
+	bool nodatasum;
+};
+
 int btrfs_mkfs_fill_dir(struct btrfs_trans_handle *trans, const char *source_dir,
 			struct btrfs_root *root, struct list_head *subvols,
+			struct list_head *inode_flags_list,
 			enum btrfs_compression_type compression,
 			unsigned int compression_level);
 u64 btrfs_mkfs_size_dir(const char *dir_name, u32 sectorsize, u64 min_dev_size,