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Commit 3558d4f8 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
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btrfs: Deprecate userspace transaction ioctls 



Userspace transactions were introduced in commit 6bf13c0c ("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: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
[ move the warning past perm checks, keep the has-been-printed state;
  we're ok with just one warning over all filesystems ]
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 9f6d2510

fs/btrfs/ioctl.c

+11 −0
Original line number Diff line number Diff line
@@ -3967,11 +3967,22 @@ static long btrfs_ioctl_trans_start(struct file *file) 
	struct btrfs_root *root = BTRFS_I(inode)->root;

	struct btrfs_trans_handle *trans;

	int ret;

	static bool warned = false;



	ret = -EPERM;

	if (!capable(CAP_SYS_ADMIN))

		goto out;



	if (!warned) {

		btrfs_warn(fs_info,

			"Userspace transaction mechanism is considered "

			"deprecated and slated to be removed in 4.17. "

			"If you have a valid use case please "

			"speak up on the mailing list");

		WARN_ON(1);

		warned = true;

	}



	ret = -EINPROGRESS;

	if (file->private_data)

		goto out;