From fb65f530001699d7be799c0dfe4407059aadb1ef Mon Sep 17 00:00:00 2001
From: Jeff Layton <jlayton@redhat.com>
Date: Mon, 1 Feb 2021 11:04:07 -0500
Subject: [PATCH] client: add ceph_ll_lookup_vino

Add a new API function for looking up an inode via a vinodeno_t. This
should give ganesha a way to reliably look up snapshot inodes.

We do need to add some special handling for CEPH_SNAPDIRs. If we're
looking for one, then find the non-snapped parent, and then call
open_snapdir to get the snapdir inode.

Also, have the function check the local cache before calling the MDS
to look up an inode.

Fixes: https://tracker.ceph.com/issues/48991
Signed-off-by: Jeff Layton <jlayton@redhat.com>
(cherry picked from commit 70622079c2ec55222a139fa5042902e0b19bd839)

Conflicts:
	src/client/Client.cc
---
 src/client/Client.cc           | 49 +++++++++++++++++++++++++++++-----
 src/client/Client.h            |  1 +
 src/include/cephfs/libcephfs.h |  4 +++
 src/libcephfs.cc               |  8 ++++++
 4 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/src/client/Client.cc b/src/client/Client.cc
index 0b5d386e14ebe..85686e703a095 100755
--- a/src/client/Client.cc
+++ b/src/client/Client.cc
@@ -10904,21 +10904,56 @@ int Client::ll_lookup(Inode *parent, const char *name, struct stat *attr,
   return r;
 }
 
-int Client::ll_lookup_inode(
-    struct inodeno_t ino,
+int Client::ll_lookup_vino(
+    vinodeno_t vino,
     const UserPerm& perms,
     Inode **inode)
 {
   ceph_assert(inode != NULL);
-  std::lock_guard lock(client_lock);
-  ldout(cct, 3) << "ll_lookup_inode " << ino << dendl;
-   
+
   if (unmounting)
     return -ENOTCONN;
 
-  // Num1: get inode and *inode
+  std::lock_guard lock(client_lock);
+  ldout(cct, 3) << __func__ << vino << dendl;
+   
+  // Check the cache first
+  unordered_map<vinodeno_t,Inode*>::iterator p = inode_map.find(vino);
+  if (p != inode_map.end()) {
+    *inode = p->second;
+    _ll_get(*inode);
+    return 0;
+  }
+
+  uint64_t snapid = vino.snapid;
+
+  // for snapdir, find the non-snapped dir inode
+  if (snapid == CEPH_SNAPDIR)
+    vino.snapid = CEPH_NOSNAP;
+
+  int r = _lookup_vino(vino, perms, inode);
+  if (r)
+    return r;
+  ceph_assert(*inode != NULL);
+
+  if (snapid == CEPH_SNAPDIR) {
+    Inode *tmp = *inode;
+
+    // open the snapdir and put the inode ref
+    *inode = open_snapdir(tmp);
+    _ll_forget(tmp, 1);
+    _ll_get(*inode);
+  }
+  return 0;
+}
+
+int Client::ll_lookup_inode(
+    struct inodeno_t ino,
+    const UserPerm& perms,
+    Inode **inode)
+{
   vinodeno_t vino(ino, CEPH_NOSNAP);
-  return _lookup_vino(vino, perms, inode);
+  return ll_lookup_vino(vino, perms, inode);
 }
 
 int Client::ll_lookupx(Inode *parent, const char *name, Inode **out,
diff --git a/src/client/Client.h b/src/client/Client.h
index fdd250e197e18..13bbc29b235c2 100644
--- a/src/client/Client.h
+++ b/src/client/Client.h
@@ -480,6 +480,7 @@ public:
   int ll_lookup(Inode *parent, const char *name, struct stat *attr,
 		Inode **out, const UserPerm& perms);
   int ll_lookup_inode(struct inodeno_t ino, const UserPerm& perms, Inode **inode);
+  int ll_lookup_vino(vinodeno_t vino, const UserPerm& perms, Inode **inode);
   int ll_lookupx(Inode *parent, const char *name, Inode **out,
 			struct ceph_statx *stx, unsigned want, unsigned flags,
 			const UserPerm& perms);
diff --git a/src/include/cephfs/libcephfs.h b/src/include/cephfs/libcephfs.h
index 94c80635030d1..f8eff8e88f762 100644
--- a/src/include/cephfs/libcephfs.h
+++ b/src/include/cephfs/libcephfs.h
@@ -1621,6 +1621,10 @@ int ceph_debug_get_file_caps(struct ceph_mount_info *cmount, const char *path);
 /* Low Level */
 struct Inode *ceph_ll_get_inode(struct ceph_mount_info *cmount,
 				vinodeno_t vino);
+
+int ceph_ll_lookup_vino(struct ceph_mount_info *cmount, vinodeno_t vino,
+			Inode **inode);
+
 int ceph_ll_lookup_inode(
     struct ceph_mount_info *cmount,
     struct inodeno_t ino,
diff --git a/src/libcephfs.cc b/src/libcephfs.cc
index c18323be43f91..5ab93541d5e39 100644
--- a/src/libcephfs.cc
+++ b/src/libcephfs.cc
@@ -1587,6 +1587,14 @@ extern "C" struct Inode *ceph_ll_get_inode(class ceph_mount_info *cmount,
 }
 
 
+extern "C" int ceph_ll_lookup_vino(
+    struct ceph_mount_info *cmount,
+    vinodeno_t vino,
+    Inode **inode)
+{
+  return (cmount->get_client())->ll_lookup_vino(vino, cmount->default_perms, inode);
+}
+
 /**
  * Populates the client cache with the requested inode, and its
  * parent dentry.
-- 
2.39.5