[PATCH V2] mkfs.btrfs: allow UUID specification at mkfs time
Allow the specification of the filesystem UUID at mkfs time.
Non-unique unique IDs are rejected.
(Implemented only for mkfs.btrfs, not btrfs-convert).
Signed-off-by: Eric Sandeen sand...@redhat.com
---
V2: reject non-unique unique IDs.
diff --git a/btrfs-convert.c b/btrfs-convert.c
index a8b2c51..d62d4f8 100644
--- a/btrfs-convert.c
+++ b/btrfs-convert.c
@@ -2240,7 +2240,7 @@ static int do_convert(const char *devname, int datacsum,
int packing,
goto fail;
}
ret = make_btrfs(fd, devname, ext2_fs-super-s_volume_name,
-blocks, total_bytes, blocksize, blocksize,
+NULL, blocks, total_bytes, blocksize, blocksize,
blocksize, blocksize, 0);
if (ret) {
fprintf(stderr, unable to create initial ctree: %s\n,
diff --git a/man/mkfs.btrfs.8.in b/man/mkfs.btrfs.8.in
index bef509d..4450d03 100644
--- a/man/mkfs.btrfs.8.in
+++ b/man/mkfs.btrfs.8.in
@@ -16,6 +16,7 @@ mkfs.btrfs \- create a btrfs filesystem
[ \fB\-r\fP\fI rootdir\fP ]
[ \fB\-K\fP ]
[ \fB\-O\fP\fI feature1,feature2,...\fP ]
+[ \fB\-U\fP\fI uuid\fP ]
[ \fB\-h\fP ]
[ \fB\-V\fP ]
\fI device\fP [ \fIdevice ...\fP ]
@@ -90,6 +91,9 @@ To see all run
\fBmkfs.btrfs -O list-all\fR
.TP
+\fB\-U\fR, \fB\-\-uuid \fR
+Create the filesystem with the specified UUID.
+.TP
\fB\-V\fR, \fB\-\-version\fR
Print the \fBmkfs.btrfs\fP version and exit.
.SH UNIT
diff --git a/mkfs.c b/mkfs.c
index dbd83f5..eccb08f 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -288,6 +288,7 @@ static void print_usage(void)
fprintf(stderr, \t -r --rootdir the source directory\n);
fprintf(stderr, \t -K --nodiscard do not perform whole device TRIM\n);
fprintf(stderr, \t -O --features comma separated list of filesystem
features\n);
+ fprintf(stderr, \t -U --uuid specify the filesystem UUID\n);
fprintf(stderr, \t -V --version print the mkfs.btrfs version and
exit\n);
fprintf(stderr, %s\n, BTRFS_BUILD_VERSION);
exit(1);
@@ -351,6 +352,7 @@ static struct option long_options[] = {
{ rootdir, 1, NULL, 'r' },
{ nodiscard, 0, NULL, 'K' },
{ features, 0, NULL, 'O' },
+ { uuid, 0, NULL, 'U' },
{ NULL, 0, NULL, 0}
};
@@ -1273,11 +1275,12 @@ int main(int ac, char **av)
int dev_cnt = 0;
int saved_optind;
char estr[100];
+ char *fs_uuid = NULL;
u64 features = DEFAULT_MKFS_FEATURES;
while(1) {
int c;
- c = getopt_long(ac, av, A:b:fl:n:s:m:d:L:O:r:VMK,
+ c = getopt_long(ac, av, A:b:fl:n:s:m:d:L:O:r:U:VMK,
long_options, option_index);
if (c 0)
break;
@@ -1346,6 +1349,9 @@ int main(int ac, char **av)
source_dir = optarg;
source_dir_set = 1;
break;
+ case 'U':
+ fs_uuid = optarg;
+ break;
case 'K':
discard = 0;
break;
@@ -1514,7 +1520,7 @@ int main(int ac, char **av)
process_fs_features(features);
- ret = make_btrfs(fd, file, label, blocks, dev_block_count,
+ ret = make_btrfs(fd, file, label, fs_uuid, blocks, dev_block_count,
nodesize, leafsize,
sectorsize, stripesize, features);
if (ret) {
diff --git a/utils.c b/utils.c
index 3e9c527..48c9bb0 100644
--- a/utils.c
+++ b/utils.c
@@ -93,12 +93,41 @@ static u64 reference_root_table[] = {
[6] = BTRFS_CSUM_TREE_OBJECTID,
};
-int make_btrfs(int fd, const char *device, const char *label,
+int test_uuid_unique(char *fs_uuid)
+{
+ int unique = 1;
+ blkid_dev_iterate iter = NULL;
+ blkid_dev dev = NULL;
+ blkid_cache cache = NULL;
+
+ if (blkid_get_cache(cache, 0) 0) {
+ printf(ERROR: lblkid cache get failed\n);
+ return 1;
+ }
+ blkid_probe_all(cache);
+ iter = blkid_dev_iterate_begin(cache);
+ blkid_dev_set_search(iter, UUID, fs_uuid);
+
+ while (blkid_dev_next(iter, dev) == 0) {
+ dev = blkid_verify(cache, dev);
+ if (dev) {
+ unique = 0;
+ break;
+ }
+ }
+
+ blkid_dev_iterate_end(iter);
+ blkid_put_cache(cache);
+
+ return unique;
+}
+
+int make_btrfs(int fd, const char *device, const char *label, char *fs_uuid,
u64 blocks[7], u64 num_bytes, u32 nodesize,
u32 leafsize, u32 sectorsize, u32 stripesize, u64 features)
{
struct btrfs_super_block super;
- struct extent_buffer *buf;
+ struct extent_buffer *buf = NULL;
struct btrfs_root_item root_item;
struct btrfs_disk_key
Re: [PATCH V2] mkfs.btrfs: allow UUID specification at mkfs time
Thanks for adding the uuid uniqueness check, that was my major
objection for previous patch iterations,
http://www.spinics.net/lists/linux-btrfs/msg30572.html
we can now use it for convert as well (to generate or copy the uuid).
On Wed, May 14, 2014 at 10:35:05AM -0500, Eric Sandeen wrote:
@@ -125,7 +154,19 @@ int make_btrfs(int fd, const char *device, const char
*label,
memset(super, 0, sizeof(super));
num_bytes = (num_bytes / sectorsize) * sectorsize;
- uuid_generate(super.fsid);
+ if (fs_uuid) {
+ if (uuid_parse(fs_uuid, super.fsid) != 0) {
+ fprintf(stderr, could not parse UUID: %s\n, fs_uuid);
+ ret = -EINVAL;
+ goto out;
I think the uuid validity check comes too late, IMHO it should be done
after the while/getopt block outside of make_btrfs. At this point eg.
the discard or device zeroing is already done.
I would not mind to keep the check here as well as a last sanity check,
though the number of mkfs_btrfs callers is 1 and the function is not
exported to the library.
+ }
+ if (!test_uuid_unique(fs_uuid)) {
+ fprintf(stderr, non-unique UUID: %s\n, fs_uuid);
+ ret = -EBUSY;
+ goto out;
+ }
+ } else
+ uuid_generate(super.fsid);
uuid_generate(super.dev_item.uuid);
uuid_generate(chunk_tree_uuid);
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Re: [PATCH V2] mkfs.btrfs: allow UUID specification at mkfs time
On 5/14/14, 11:01 AM, David Sterba wrote:
Thanks for adding the uuid uniqueness check, that was my major
objection for previous patch iterations,
http://www.spinics.net/lists/linux-btrfs/msg30572.html
Ah, thanks, I didn't know about that history, I'm sorry.
I'm not sure if my duplicate-check is over the top, you had suggested
blkid_probe_lookup_value()
before, maybe that's simpler. I'm not a blkid expert... but it seems to work.
we can now use it for convert as well (to generate or copy the uuid).
woo ;)
-Eric
On Wed, May 14, 2014 at 10:35:05AM -0500, Eric Sandeen wrote:
@@ -125,7 +154,19 @@ int make_btrfs(int fd, const char *device, const char
*label,
memset(super, 0, sizeof(super));
num_bytes = (num_bytes / sectorsize) * sectorsize;
-uuid_generate(super.fsid);
+if (fs_uuid) {
+if (uuid_parse(fs_uuid, super.fsid) != 0) {
+fprintf(stderr, could not parse UUID: %s\n, fs_uuid);
+ret = -EINVAL;
+goto out;
I think the uuid validity check comes too late, IMHO it should be done
after the while/getopt block outside of make_btrfs. At this point eg.
the discard or device zeroing is already done.
I would not mind to keep the check here as well as a last sanity check,
though the number of mkfs_btrfs callers is 1 and the function is not
exported to the library.
+}
+if (!test_uuid_unique(fs_uuid)) {
+fprintf(stderr, non-unique UUID: %s\n, fs_uuid);
+ret = -EBUSY;
+goto out;
+}
+} else
+uuid_generate(super.fsid);
uuid_generate(super.dev_item.uuid);
uuid_generate(chunk_tree_uuid);
--
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Re: [PATCH V2] mkfs.btrfs: allow UUID specification at mkfs time
On 05/14/2014 06:01 PM, David Sterba wrote:
On Wed, May 14, 2014 at 10:35:05AM -0500, Eric Sandeen wrote:
@@ -125,7 +154,19 @@ int make_btrfs(int fd, const char *device, const char
*label,
memset(super, 0, sizeof(super));
num_bytes = (num_bytes / sectorsize) * sectorsize;
- uuid_generate(super.fsid);
+ if (fs_uuid) {
+ if (uuid_parse(fs_uuid, super.fsid) != 0) {
+ fprintf(stderr, could not parse UUID: %s\n, fs_uuid);
+ ret = -EINVAL;
+ goto out;
I think the uuid validity check comes too late, IMHO it should be done
after the while/getopt block outside of make_btrfs. At this point eg.
the discard or device zeroing is already done.
Pay attention that, if you don't change the test_uuid_unique() you need to
perform the check after zeroing the disk, or otherwise you are not able to mkfs
the same disk with the same UUID (I suspect that this is a real use case for
testing).
I am still convinced that a Warning is a better way to handle these kind of
situations.
As reported before, forcing a unique UUID to be not unique is a thing to
skilled person. The problem is that BTRFS in this regard behaves differently
respect other file-systems, and even a skilled person could not be aware of the
possible problem.
In this case is better to provide a complete information, instead of
complicating the things adding further check.
BR
G.Baroncelli
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