[PATCH v3 1/4] uuid: Add inline helpers to import / export UUIDs

[PATCH v3 1/4] uuid: Add inline helpers to import / export UUIDs

[Andy Shevchenko]

Sometimes we may need to import UUID from or export to the raw buffer,
which is provided outside of kernel and can't be declared as UUID type.
With current API this operation will require an explicit casting
to one of UUID types and length, that is always a constant derived as sizeof
the certain UUID type.

Provide a helpful set of inline helpers to minimize developer's effort
in the cases when raw buffers are involved.

Suggested-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/uuid.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/uuid.h b/include/linux/uuid.h
index 0c631e2a73b6..8e4a5000da03 100644
--- a/include/linux/uuid.h
+++ b/include/linux/uuid.h
@@ -43,6 +43,16 @@ static inline void guid_copy(guid_t *dst, const guid_t *src)
 	memcpy(dst, src, sizeof(guid_t));
 }
 
+static inline void import_guid(guid_t *dst, const __u8 *src)
+{
+	memcpy(dst, src, sizeof(guid_t));
+}
+
+static inline void export_guid(__u8 *dst, const guid_t *src)
+{
+	memcpy(dst, src, sizeof(guid_t));
+}
+
 static inline bool guid_is_null(const guid_t *guid)
 {
 	return guid_equal(guid, &guid_null);
@@ -58,6 +68,16 @@ static inline void uuid_copy(uuid_t *dst, const uuid_t *src)
 	memcpy(dst, src, sizeof(uuid_t));
 }
 
+static inline void import_uuid(uuid_t *dst, const __u8 *src)
+{
+	memcpy(dst, src, sizeof(uuid_t));
+}
+
+static inline void export_uuid(__u8 *dst, const uuid_t *src)
+{
+	memcpy(dst, src, sizeof(uuid_t));
+}
+
 static inline bool uuid_is_null(const uuid_t *uuid)
 {
 	return uuid_equal(uuid, &uuid_null);
-- 
2.20.1

[PATCH v3 2/4] uuid: Provide a GUID generator for raw buffer

[Andy Shevchenko]

In some cases we would like to generate a GUID and export it.
Though it would require either casting to internal kernel types or
an intermediate buffer. Instead we may achieve this by supplying
a pointer to raw buffer and make a complimentary API to existing one
for UUIDs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/uuid.h |  1 +
 lib/uuid.c           | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/include/linux/uuid.h b/include/linux/uuid.h
index 8e4a5000da03..3780460a9a85 100644
--- a/include/linux/uuid.h
+++ b/include/linux/uuid.h
@@ -84,6 +84,7 @@ static inline bool uuid_is_null(const uuid_t *uuid)
 }
 
 void generate_random_uuid(unsigned char uuid[16]);
+void generate_random_guid(unsigned char guid[16]);
 
 extern void guid_gen(guid_t *u);
 extern void uuid_gen(uuid_t *u);
diff --git a/lib/uuid.c b/lib/uuid.c
index b6a1edb61d87..562d53977cab 100644
--- a/lib/uuid.c
+++ b/lib/uuid.c
@@ -40,6 +40,16 @@ void generate_random_uuid(unsigned char uuid[16])
 }
 EXPORT_SYMBOL(generate_random_uuid);
 
+void generate_random_guid(unsigned char guid[16])
+{
+	get_random_bytes(guid, 16);
+	/* Set GUID version to 4 --- truly random generation */
+	guid[7] = (guid[7] & 0x0F) | 0x40;
+	/* Set the GUID variant to DCE */
+	guid[8] = (guid[8] & 0x3F) | 0x80;
+}
+EXPORT_SYMBOL(generate_random_guid);
+
 static void __uuid_gen_common(__u8 b[16])
 {
 	prandom_bytes(b, 16);
-- 
2.20.1

[PATCH v3 3/4] Btrfs: Switch to use new generic UUID API

[Andy Shevchenko]

There are new types and helpers that are supposed to be used in new code.

As a preparation to get rid of legacy types and API functions do
the conversion here.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 fs/btrfs/disk-io.c     | 6 +++---
 fs/btrfs/ioctl.c       | 4 +---
 fs/btrfs/root-tree.c   | 4 +---
 fs/btrfs/transaction.c | 7 +++----
 4 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 41a2bd2e0c56..6a9f51d86bd1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1259,7 +1259,6 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	struct btrfs_key key;
 	unsigned int nofs_flag;
 	int ret = 0;
-	uuid_le uuid = NULL_UUID_LE;
 
 	/*
 	 * We're holding a transaction handle, so use a NOFS memory allocation
@@ -1299,8 +1298,9 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	btrfs_set_root_last_snapshot(&root->root_item, 0);
 	btrfs_set_root_dirid(&root->root_item, 0);
 	if (is_fstree(objectid))
-		uuid_le_gen(&uuid);
-	memcpy(root->root_item.uuid, uuid.b, BTRFS_UUID_SIZE);
+		generate_random_guid(root->root_item.uuid);
+	else
+		export_guid(root->root_item.uuid, &guid_null);
 	root->root_item.drop_level = 0;
 
 	key.objectid = objectid;
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 818f7ec8bb0e..88a7579b217b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -573,7 +573,6 @@ static noinline int create_subvol(struct inode *dir,
 	u64 objectid;
 	u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
 	u64 index = 0;
-	uuid_le new_uuid;
 
 	root_item = kzalloc(sizeof(*root_item), GFP_KERNEL);
 	if (!root_item)
@@ -643,8 +642,7 @@ static noinline int create_subvol(struct inode *dir,
 
 	btrfs_set_root_generation_v2(root_item,
 			btrfs_root_generation(root_item));
-	uuid_le_gen(&new_uuid);
-	memcpy(root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
+	generate_random_guid(root_item->uuid);
 	btrfs_set_stack_timespec_sec(&root_item->otime, cur_time.tv_sec);
 	btrfs_set_stack_timespec_nsec(&root_item->otime, cur_time.tv_nsec);
 	root_item->ctime = root_item->otime;
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 47733fb55df7..af884338bbb1 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -22,7 +22,6 @@
 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
 				struct btrfs_root_item *item)
 {
-	uuid_le uuid;
 	u32 len;
 	int need_reset = 0;
 
@@ -44,8 +43,7 @@ static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
 			sizeof(*item) - offsetof(struct btrfs_root_item,
 					generation_v2));
 
-		uuid_le_gen(&uuid);
-		memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
+		generate_random_guid(item->uuid);
 	}
 }
 
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 3b8ae1a8f02d..7aec9389df69 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1395,7 +1395,6 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	u64 index = 0;
 	u64 objectid;
 	u64 root_flags;
-	uuid_le new_uuid;
 
 	ASSERT(pending->path);
 	path = pending->path;
@@ -1488,8 +1487,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 
 	btrfs_set_root_generation_v2(new_root_item,
 			trans->transid);
-	uuid_le_gen(&new_uuid);
-	memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
+	generate_random_guid(new_root_item->uuid);
 	memcpy(new_root_item->parent_uuid, root->root_item.uuid,
 			BTRFS_UUID_SIZE);
 	if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
@@ -1600,7 +1598,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 		btrfs_abort_transaction(trans, ret);
 		goto fail;
 	}
-	ret = btrfs_uuid_tree_add(trans, new_uuid.b, BTRFS_UUID_KEY_SUBVOL,
+	ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,
+				  BTRFS_UUID_KEY_SUBVOL,
 				  objectid);
 	if (ret) {
 		btrfs_abort_transaction(trans, ret);
-- 
2.20.1

Re: [PATCH v3 3/4] Btrfs: Switch to use new generic UUID API

[Johannes Thumshirn]

On Wed, Jul 17, 2019 at 02:36:32PM +0300, Andy Shevchenko wrote:
> There are new types and helpers that are supposed to be used in new code.
> 
> As a preparation to get rid of legacy types and API functions do
> the conversion here.

Why? What was broken in the old versions? What benefit do we have apart from
unneeded churn?

Thanks,
	Johannes
-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH v3 3/4] Btrfs: Switch to use new generic UUID API

[Andy Shevchenko]

On Thu, Jul 18, 2019 at 07:20:17PM +0200, Johannes Thumshirn wrote:
> On Wed, Jul 17, 2019 at 02:36:32PM +0300, Andy Shevchenko wrote:
> > There are new types and helpers that are supposed to be used in new code.
> > 
> > As a preparation to get rid of legacy types and API functions do
> > the conversion here.
> 
> Why? What was broken in the old versions? What benefit do we have apart from
> unneeded churn?

I think Christoph can explain this better than me.

By the way, if you look to the headers, there is no more "old" API, it's
covered as alias to the new one.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 3/4] Btrfs: Switch to use new generic UUID API

[Johannes Thumshirn]

On Thu, Jul 18, 2019 at 08:38:42PM +0300, Andy Shevchenko wrote:
> On Thu, Jul 18, 2019 at 07:20:17PM +0200, Johannes Thumshirn wrote:
> > On Wed, Jul 17, 2019 at 02:36:32PM +0300, Andy Shevchenko wrote:
> > > There are new types and helpers that are supposed to be used in new code.
> > > 
> > > As a preparation to get rid of legacy types and API functions do
> > > the conversion here.
> > 
> > Why? What was broken in the old versions? What benefit do we have apart from
> > unneeded churn?
> 
> I think Christoph can explain this better than me.
> 
> By the way, if you look to the headers, there is no more "old" API, it's
> covered as alias to the new one.

AFAIU it's mostly the naming that causes problems here as a little endian UUID
doesn't really exits, is called GUID.

But please at least document this in a cover letter. Also what tests did you
make? I know most of these functions have their origin in XFS.

Thanks,
	Johannes
-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

Re: [PATCH v3 3/4] Btrfs: Switch to use new generic UUID API

[Andy Shevchenko]

On Thu, Jul 18, 2019 at 07:44:00PM +0200, Johannes Thumshirn wrote:
> On Thu, Jul 18, 2019 at 08:38:42PM +0300, Andy Shevchenko wrote:
> > On Thu, Jul 18, 2019 at 07:20:17PM +0200, Johannes Thumshirn wrote:
> > > On Wed, Jul 17, 2019 at 02:36:32PM +0300, Andy Shevchenko wrote:
> > > > There are new types and helpers that are supposed to be used in new code.
> > > > 
> > > > As a preparation to get rid of legacy types and API functions do
> > > > the conversion here.
> > > 
> > > Why? What was broken in the old versions? What benefit do we have apart from
> > > unneeded churn?
> > 
> > I think Christoph can explain this better than me.
> > 
> > By the way, if you look to the headers, there is no more "old" API, it's
> > covered as alias to the new one.
> 
> AFAIU it's mostly the naming that causes problems here as a little endian UUID
> doesn't really exits, is called GUID.

Yes, that's the main point for now.

> But please at least document this in a cover letter. Also what tests did you
> make? I know most of these functions have their origin in XFS.

I did only compile test.

-- 
With Best Regards,
Andy Shevchenko

[PATCH v3 4/4] uuid: Remove no more needed macro

[Andy Shevchenko]

uuid_le_gen() is no used anymore, remove it for good.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/uuid.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/linux/uuid.h b/include/linux/uuid.h
index 3780460a9a85..d41b0d3e9474 100644
--- a/include/linux/uuid.h
+++ b/include/linux/uuid.h
@@ -98,7 +98,6 @@ int guid_parse(const char *uuid, guid_t *u);
 int uuid_parse(const char *uuid, uuid_t *u);
 
 /* backwards compatibility, don't use in new code */
-#define uuid_le_gen(u)		guid_gen(u)
 #define uuid_le_to_bin(guid, u)	guid_parse(guid, u)
 
 static inline int uuid_le_cmp(const guid_t u1, const guid_t u2)
-- 
2.20.1