btrfs: Don't generate UUID for non-fs tree

PATCH In review Qu Wenruo 3 participants 6 messages Oct 31, 2017 – Jan 5, 2018 Btrfs file system

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Qu Wenruo

author

2017-10-31 06:08 UTC #0 lore raw

PATCH 1/1 btrfs: Don't generate UUID for non-fs tree

btrfs_create_tree() will unconditionally generate UUID for any root. So for quota tree and data reloc tree created by kernel, they will have unique UUIDs.

However UUID in root item is only referred by UUID tree, which only records UUID for fs trees.
This makes unique UUIDs for quota/data reloc tree meaningless.

Leave the UUID as zero for non-fs tree, making btrfs-debug-tree output less confusing.

Reported-by Misono Tomohiro <[email protected]>

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

---
 fs/btrfs/disk-io.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

fs/btrfs/disk-io.c +3 -2

index dfdab849037b..d85e04a675fe 100644
@@ -1403,7 +1403,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	struct btrfs_root *root;
 	struct btrfs_key key;
 	int ret = 0;
-	uuid_le uuid;
+	uuid_le uuid = { 0 };
 
 	root = btrfs_alloc_root(fs_info, GFP_KERNEL);
 	if (!root)

@@ -1444,7 +1444,8 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	btrfs_set_root_used(&root->root_item, leaf->len);
 	btrfs_set_root_last_snapshot(&root->root_item, 0);
 	btrfs_set_root_dirid(&root->root_item, 0);
-	uuid_le_gen(&uuid);
+	if (is_fstree(objectid))
+		uuid_le_gen(&uuid);
 	memcpy(root->root_item.uuid, uuid.b, BTRFS_UUID_SIZE);
 	root->root_item.drop_level = 0;

Signature · 1 line

2.14.3

David Sterba

Reviewed-by on v1 1/1

2017-11-06 15:30 UTC #1 lore raw

Quoted 4 lines · Qu Wenruo

btrfs_create_tree() will unconditionally generate UUID for any root. So for quota tree and data reloc tree created by kernel, they will have unique UUIDs.

Quoted 8 lines

However UUID in root item is only referred by UUID tree, which only records UUID for fs trees.
This makes unique UUIDs for quota/data reloc tree meaningless.
Leave the UUID as zero for non-fs tree, making btrfs-debug-tree output less confusing.
Reported-by Misono Tomohiro <[email protected]>

Can you please point me to the report?

Quoted 1 line

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

Reviewed-by David Sterba <[email protected]>

Qu Wenruo

2017-11-07 00:43 UTC #2 lore raw

Quoted 9 lines · David Sterba

Quoted 8 lines · Qu Wenruo
btrfs_create_tree() will unconditionally generate UUID for any root. So for quota tree and data reloc tree created by kernel, they will have unique UUIDs.
However UUID in root item is only referred by UUID tree, which only records UUID for fs trees.
This makes unique UUIDs for quota/data reloc tree meaningless.

Quoted 6 lines

Quoted 4 lines
Leave the UUID as zero for non-fs tree, making btrfs-debug-tree output less confusing.
Reported-by Misono Tomohiro <[email protected]>
Can you please point me to the report?

Here it is:

https://marc.info/?l=linux-btrfs&m=150941856508074&w=2

Thanks,
Qu

Quoted 9 lines

Quoted 2 lines
Signed-off-by Qu Wenruo <[email protected]>
Reviewed-by David Sterba <[email protected]>
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David Sterba

2018-01-03 14:39 UTC #3 lore raw

In reply to Qu Wenruo

Quoted 22 lines · Qu Wenruo

btrfs_create_tree() will unconditionally generate UUID for any root. So for quota tree and data reloc tree created by kernel, they will have unique UUIDs.
However UUID in root item is only referred by UUID tree, which only records UUID for fs trees.
This makes unique UUIDs for quota/data reloc tree meaningless.
Leave the UUID as zero for non-fs tree, making btrfs-debug-tree output less confusing.
Reported-by Misono Tomohiro <[email protected]>
Signed-off-by Qu Wenruo <[email protected]>
---
 fs/btrfs/disk-io.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
fs/btrfs/disk-io.c +0 -0
index dfdab849037b..d85e04a675fe 100644

fs/btrfs/disk-io.c struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans, · line 1406

Quoted 5 lines

fs/btrfs/disk-io.c +1 -1

@@ -1403,7 +1403,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	struct btrfs_root *root;
 	struct btrfs_key key;
 	int ret = 0;
-	uuid_le uuid;
+	uuid_le uuid = { 0 };

I get a warning with gcc 4.8.5

fs/btrfs/disk-io.c:1236:2: warning: missing braces around initializer [-Wmissing-braces]

but no warning with gcc 7.2.1 (built as 'make ccflags-y=-Wmissing-braces and checking that the option is really there). I think we should use NULL_UUID_LE.

Qu Wenruo

2018-01-04 01:39 UTC #4 lore raw

Quoted 31 lines · David Sterba

Quoted 22 lines · Qu Wenruo
btrfs_create_tree() will unconditionally generate UUID for any root. So for quota tree and data reloc tree created by kernel, they will have unique UUIDs.
However UUID in root item is only referred by UUID tree, which only records UUID for fs trees.
This makes unique UUIDs for quota/data reloc tree meaningless.
Leave the UUID as zero for non-fs tree, making btrfs-debug-tree output less confusing.
Reported-by Misono Tomohiro <[email protected]>
Signed-off-by Qu Wenruo <[email protected]>
---
 fs/btrfs/disk-io.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
fs/btrfs/disk-io.c +0 -0
index dfdab849037b..d85e04a675fe 100644
fs/btrfs/disk-io.c struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans, · line 1406
Quoted 5 lines
fs/btrfs/disk-io.c +1 -1
@@ -1403,7 +1403,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	struct btrfs_root *root;
 	struct btrfs_key key;
 	int ret = 0;
-	uuid_le uuid;
+	uuid_le uuid = { 0 };
I get a warning with gcc 4.8.5

Quoted 5 lines

fs/btrfs/disk-io.c:1236:2: warning: missing braces around initializer [-Wmissing-braces]
but no warning with gcc 7.2.1 (built as 'make ccflags-y=-Wmissing-braces and checking that the option is really there). I think we should use NULL_UUID_LE.

Do I need to resend the whole patch or a new delta patch?

Thanks,
Qu

Quoted 5 lines

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David Sterba

2018-01-05 12:50 UTC #5 lore raw

Quoted 5 lines · Qu Wenruo

Quoted 5 lines
fs/btrfs/disk-io.c struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans, · line 1406
Quoted 2 lines
fs/btrfs/disk-io.c +1 -1
-	uuid_le uuid;
+	uuid_le uuid = { 0 };
I get a warning with gcc 4.8.5

Quoted 7 lines

Quoted 5 lines
fs/btrfs/disk-io.c:1236:2: warning: missing braces around initializer [-Wmissing-braces]
but no warning with gcc 7.2.1 (built as 'make ccflags-y=-Wmissing-braces and checking that the option is really there). I think we should use NULL_UUID_LE.
Do I need to resend the whole patch or a new delta patch?

Not needed, I've fixed in the patch,

uuid_le = NULL_UUID_LE;