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btrfs-progs: mkfs: add new option --subvol
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Add a new option --subvol, which tells mkfs.btrfs to create the
specified directories as subvolumes when used with --rootdir.

Given a populated directory dir, the command

  $ mkfs.btrfs --rootdir dir --subvol usr --subvol home --subvol home/username img

will create subvolumes 'usr' and 'home' within the toplevel subvolume,
and subvolume 'username' within the 'home' subvolume. It will fail if
any of the directories do not yet exist.

Pull-request: #868
Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Mark Harmstone <[email protected]>
Signed-off-by: David Sterba <[email protected]>
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@maharmstone @kdave
maharmstone authored and kdave committed Aug 15, 2024
1 parent 0e11b21 commit 082ce75
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5 changes: 5 additions & 0 deletions Documentation/mkfs.btrfs.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -155,6 +155,11 @@ OPTIONS
contain the files from *rootdir*. Since version 4.14.1 the filesystem size is
not minimized. Please see option *--shrink* if you need that functionality.

-u|--subvol <subdir>
Specify that *subdir* is to be created as a subvolume rather than a regular
directory. The option *--rootdir* must also be specified, and *subdir* must be an
existing subdirectory within it. This option can be specified multiple times.

--shrink
Shrink the filesystem to its minimal size, only works with *--rootdir* option.

Expand Down
162 changes: 150 additions & 12 deletions mkfs/main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -440,6 +440,7 @@ static const char * const mkfs_usage[] = {
"Creation:",
OPTLINE("-b|--byte-count SIZE", "set size of each device to SIZE (filesystem size is sum of all device sizes)"),
OPTLINE("-r|--rootdir DIR", "copy files from DIR to the image root directory"),
OPTLINE("-u|--subvol SUBDIR", "create SUBDIR as subvolume rather than normal directory, can be specified multiple times"),
OPTLINE("--shrink", "(with --rootdir) shrink the filled filesystem to minimal size"),
OPTLINE("-K|--nodiscard", "do not perform whole device TRIM"),
OPTLINE("-f|--force", "force overwrite of existing filesystem"),
Expand Down Expand Up @@ -1055,6 +1056,9 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
char *label = NULL;
int nr_global_roots = sysconf(_SC_NPROCESSORS_ONLN);
char *source_dir = NULL;
size_t source_dir_len = 0;
struct rootdir_subvol *rds;
LIST_HEAD(subvols);

cpu_detect_flags();
hash_init_accel();
Expand Down Expand Up @@ -1085,6 +1089,7 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
{ "data", required_argument, NULL, 'd' },
{ "version", no_argument, NULL, 'V' },
{ "rootdir", required_argument, NULL, 'r' },
{ "subvol", required_argument, NULL, 'u' },
{ "nodiscard", no_argument, NULL, 'K' },
{ "features", required_argument, NULL, 'O' },
{ "runtime-features", required_argument, NULL, 'R' },
Expand All @@ -1102,7 +1107,7 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
{ NULL, 0, NULL, 0}
};

c = getopt_long(argc, argv, "A:b:fl:n:s:m:d:L:R:O:r:U:VvMKq",
c = getopt_long(argc, argv, "A:b:fl:n:s:m:d:L:R:O:r:U:VvMKqu:",
long_options, NULL);
if (c < 0)
break;
Expand Down Expand Up @@ -1208,6 +1213,22 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
free(source_dir);
source_dir = strdup(optarg);
break;
case 'u': {
struct rootdir_subvol *subvol;

subvol = malloc(sizeof(struct rootdir_subvol));
if (!subvol) {
error_msg(ERROR_MSG_MEMORY, NULL);
ret = 1;
goto error;
}

subvol->dir = strdup(optarg);
subvol->full_path = NULL;

list_add_tail(&subvol->list, &subvols);
break;
}
case 'U':
strncpy_null(fs_uuid, optarg, BTRFS_UUID_UNPARSED_SIZE);
break;
Expand Down Expand Up @@ -1272,6 +1293,89 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
ret = 1;
goto error;
}
if (!list_empty(&subvols) && source_dir == NULL) {
error("option --subvol must be used with --rootdir");
ret = 1;
goto error;
}

if (source_dir) {
char *canonical = realpath(source_dir, NULL);

if (!canonical) {
error("could not get canonical path to %s", source_dir);
ret = 1;
goto error;
}

free(source_dir);
source_dir = canonical;
source_dir_len = strlen(source_dir);
}

list_for_each_entry(rds, &subvols, list) {
char *path, *canonical;
struct rootdir_subvol *rds2;
size_t dir_len;

dir_len = strlen(rds->dir);

path = malloc(source_dir_len + 1 + dir_len + 1);
if (!path) {
error_msg(ERROR_MSG_MEMORY, NULL);
ret = 1;
goto error;
}

memcpy(path, source_dir, source_dir_len);
path[source_dir_len] = '/';
memcpy(path + source_dir_len + 1, rds->dir, dir_len + 1);

canonical = realpath(path, NULL);
if (!canonical) {
error("could not get canonical path to %s", rds->dir);
free(path);
ret = 1;
goto error;
}

free(path);
path = canonical;

if (!path_exists(path)) {
error("subvolume %s does not exist", rds->dir);
free(path);
ret = 1;
goto error;
}

if (!path_is_dir(path)) {
error("subvolume %s is not a directory", rds->dir);
free(path);
ret = 1;
goto error;
}

rds->full_path = path;

if (strlen(path) < source_dir_len + 1 ||
memcmp(path, source_dir, source_dir_len) != 0 ||
path[source_dir_len] != '/') {
error("subvolume %s is not a child of %s", rds->dir, source_dir);
ret = 1;
goto error;
}

for (rds2 = list_first_entry(&subvols, struct rootdir_subvol, list);
rds2 != rds;
rds2 = list_next_entry(rds2, list)) {
if (strcmp(rds2->full_path, path) == 0) {
error("subvolume %s specified more than once", rds->dir);
ret = 1;
goto error;
}
}
}

if (*fs_uuid) {
uuid_t dummy_uuid;
Expand Down Expand Up @@ -1821,24 +1925,37 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
error_msg(ERROR_MSG_START_TRANS, "%m");
goto out;
}
ret = btrfs_rebuild_uuid_tree(fs_info);
if (ret < 0)
goto out;

ret = cleanup_temp_chunks(fs_info, &allocation, data_profile,
metadata_profile, metadata_profile);
if (ret < 0) {
error("failed to cleanup temporary chunks: %d", ret);
goto out;
}

if (source_dir) {
pr_verbose(LOG_DEFAULT, "Rootdir from: %s\n", source_dir);
ret = btrfs_mkfs_fill_dir(source_dir, root);

trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
errno = -PTR_ERR(trans);
error_msg(ERROR_MSG_START_TRANS, "%m");
goto out;
}

ret = btrfs_mkfs_fill_dir(trans, source_dir, root,
&subvols);
if (ret) {
error("error while filling filesystem: %d", ret);
btrfs_abort_transaction(trans, ret);
goto out;
}

ret = btrfs_commit_transaction(trans, root);
if (ret) {
errno = -ret;
error_msg(ERROR_MSG_COMMIT_TRANS, "%m");
goto out;
}

list_for_each_entry(rds, &subvols, list) {
pr_verbose(LOG_DEFAULT, " Subvolume: %s\n",
rds->full_path);
}

if (shrink_rootdir) {
pr_verbose(LOG_DEFAULT, " Shrink: yes\n");
ret = btrfs_mkfs_shrink_fs(fs_info, &shrink_size,
Expand All @@ -1853,6 +1970,17 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
}
}

ret = btrfs_rebuild_uuid_tree(fs_info);
if (ret < 0)
goto out;

ret = cleanup_temp_chunks(fs_info, &allocation, data_profile,
metadata_profile, metadata_profile);
if (ret < 0) {
error("failed to cleanup temporary chunks: %d", ret);
goto out;
}

if (features.runtime_flags & BTRFS_FEATURE_RUNTIME_QUOTA ||
features.incompat_flags & BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA) {
ret = setup_quota_root(fs_info);
Expand Down Expand Up @@ -1946,6 +2074,16 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
free(label);
free(source_dir);

while (!list_empty(&subvols)) {
struct rootdir_subvol *head;

head = list_entry(subvols.next, struct rootdir_subvol, list);
free(head->dir);
free(head->full_path);
list_del(&head->list);
free(head);
}

return !!ret;

success:
Expand Down
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