ceph: preallocate inode for ops that may create one

When creating a new inode, we need to determine the crypto context
before we can transmit the RPC. The fscrypt API has a routine for getting
a crypto context before a create occurs, but it requires an inode.

Change the ceph code to preallocate an inode in advance of a create of
any sort (open(), mknod(), symlink(), etc). Move the existing code that
generates the ACL and SELinux blobs into this routine since that's
mostly common across all the different codepaths.

In most cases, we just want to allow ceph_fill_trace to use that inode
after the reply comes in, so add a new field to the MDS request for it
(r_new_inode).

The async create codepath is a bit different though. In that case, we
want to hash the inode in advance of the RPC so that it can be used
before the reply comes in. If the call subsequently fails with
-EJUKEBOX, then just put the references and clean up the as_ctx. Note
that with this change, we now need to regenerate the as_ctx when this
occurs, but it's quite rare for it to happen.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-and-tested-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 15 insertions, 2 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 5fb367b1d4b0..73dfea88bb88 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -945,6 +945,7 @@ void ceph_mdsc_release_request(struct kref *kref)
 		iput(req->r_parent);
 	}
 	iput(req->r_target_inode);
+	iput(req->r_new_inode);
 	if (req->r_dentry)
 		dput(req->r_dentry);
 	if (req->r_old_dentry)
@@ -3357,13 +3358,25 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
 
 	/* Must find target inode outside of mutexes to avoid deadlocks */
 	if ((err >= 0) && rinfo->head->is_target) {
-		struct inode *in;
+		struct inode *in = xchg(&req->r_new_inode, NULL);
 		struct ceph_vino tvino = {
 			.ino  = le64_to_cpu(rinfo->targeti.in->ino),
 			.snap = le64_to_cpu(rinfo->targeti.in->snapid)
 		};
 
-		in = ceph_get_inode(mdsc->fsc->sb, tvino);
+		/*
+		 * If we ended up opening an existing inode, discard
+		 * r_new_inode
+		 */
+		if (req->r_op == CEPH_MDS_OP_CREATE &&
+		    !req->r_reply_info.has_create_ino) {
+			/* This should never happen on an async create */
+			WARN_ON_ONCE(req->r_deleg_ino);
+			iput(in);
+			in = NULL;
+		}
+
+		in = ceph_get_inode(mdsc->fsc->sb, tvino, in);
 		if (IS_ERR(in)) {
 			err = PTR_ERR(in);
 			mutex_lock(&session->s_mutex);