Commit 3558d4f8 authored Jul 26, 2017 by Nikolay Borisov Committed by David Sterba Aug 16, 2017

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: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David 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: David 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;

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