Userspace transactions were introduced in commit
6bf13c0cc833 ("Btrfs: transaction ioctls") to provide semantics that Ceph's
object store required. However, things have changed significantly since then,
to the point where btrfs is no longer suitable as a backend for ceph and in fact
it's actively advised against such usages. Considering this, there doesn't
seem to be a widespread, legit use case of userspace transaction. They also
clutter the file->private pointer.
So to end the agony let's nuke the userspace transaction ioctls. As a first
step let's give time for people to voice their objection by just WARN()ining
when the userspace transaction is used.
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
---
fs/btrfs/ioctl.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fa1b78cf25f6..10d78d71df96 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4000,6 +4000,12 @@ static long btrfs_ioctl_trans_start(struct file *file)
struct btrfs_trans_handle *trans;
int ret;
+ btrfs_warn(fs_info, "Userspace transaction mechanism is considered
+ deprecated and slated to be removed in the near future "
+ "(1 or 2 releases). If you have a valid use case please
+ speak up on the mailing list");
+ WARN_ON_ONCE(1);
+
ret = -EPERM;
if (!capable(CAP_SYS_ADMIN))
goto out;
--
2.7.4
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