On 10/05/2017 04:22 PM, Nikolay Borisov wrote:
Currently when a read-only snapshot is received and subsequently its ro property
is set to false i.e. switched to rw-mode the received_uuid of that subvol
remains
intact. However, once the received volume is switched to RW mode we cannot
guaranteee that it contains the same data, so it makes sense to remove the
received uuid. The presence of the received_uuid can also cause problems when
the volume is being send.
Wonder if this [1] approach was considered
[1]
- set a flag on the subvolume to indicate its dirtied so that
received_uuid can be kept forever just in case if user needs it for some
reference at a later point of time.
Thanks, Anand
Signed-off-by: Nikolay Borisov <nbori...@suse.com>
Suggested-by: David Sterba <dste...@suse.cz>
---
v4:
* Put the uuid tree removal code after the lightweight 'send in progress'
check and don't move btrfs_start_transaction as suggested by David
v3:
* Rework the patch considering latest feedback from David Sterba i.e.
explicitly use btrfs_end_transaction
fs/btrfs/ioctl.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ee4ee7cbba72..9328c091854b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1775,6 +1775,7 @@ static noinline int btrfs_ioctl_subvol_setflags(struct
file *file,
struct btrfs_trans_handle *trans;
u64 root_flags;
u64 flags;
+ bool clear_received_uuid = false;
int ret = 0;
if (!inode_owner_or_capable(inode))
@@ -1824,6 +1825,7 @@ static noinline int btrfs_ioctl_subvol_setflags(struct
file *file,
btrfs_set_root_flags(&root->root_item,
root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY);
spin_unlock(&root->root_item_lock);
+ clear_received_uuid = true;
} else {
spin_unlock(&root->root_item_lock);
btrfs_warn(fs_info,
@@ -1840,6 +1842,24 @@ static noinline int btrfs_ioctl_subvol_setflags(struct
file *file,
goto out_reset;
}
+ if (clear_received_uuid) {
+ if (!btrfs_is_empty_uuid(root->root_item.received_uuid)) {
+ ret = btrfs_uuid_tree_rem(trans, fs_info,
+ root->root_item.received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ root->root_key.objectid);
+
+ if (ret && ret != -ENOENT) {
+ btrfs_abort_transaction(trans, ret);
+ btrfs_end_transaction(trans);
+ goto out_reset;
+ }
+
+ memset(root->root_item.received_uuid, 0,
+ BTRFS_UUID_SIZE);
+ }
+ }
+
ret = btrfs_update_root(trans, fs_info->tree_root,
&root->root_key, &root->root_item);
if (ret < 0) {
--
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