[PATCH 3/6] ceph: return the correct dentry on mkdir

[NeilBrown]

ceph already splices the correct dentry (in splice_dentry()) from the
result of mkdir but does nothing more with it.

Now that ->mkdir can return a dentry, return the correct dentry.

Note that previously ceph_mkdir() could call
   ceph_init_inode_acls()
on the inode from the wrong dentry, which would be NULL.  This
is safe as ceph_init_inode_acls() checks for NULL, but is not
strictly correct.  With this patch, the inode for the returned dentry
is passed to ceph_init_inode_acls().

Reviewed-by: Viacheslav Dubeyko <slava.dube...@ibm.com>
Signed-off-by: NeilBrown <ne...@suse.de>
---
 fs/ceph/dir.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 39e0f240de06..5e98394e2dca 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1099,6 +1099,7 @@ static struct dentry *ceph_mkdir(struct mnt_idmap *idmap, 
struct inode *dir,
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req;
        struct ceph_acl_sec_ctx as_ctx = {};
+       struc dentry *ret;
        int err;
        int op;
 
@@ -1116,32 +1117,32 @@ static struct dentry *ceph_mkdir(struct mnt_idmap 
*idmap, struct inode *dir,
                      ceph_vinop(dir), dentry, dentry, mode);
                op = CEPH_MDS_OP_MKDIR;
        } else {
-               err = -EROFS;
+               ret = ERR_PTR(-EROFS);
                goto out;
        }
 
        if (op == CEPH_MDS_OP_MKDIR &&
            ceph_quota_is_max_files_exceeded(dir)) {
-               err = -EDQUOT;
+               ret = ERR_PTR(-EDQUOT);
                goto out;
        }
        if ((op == CEPH_MDS_OP_MKSNAP) && IS_ENCRYPTED(dir) &&
            !fscrypt_has_encryption_key(dir)) {
-               err = -ENOKEY;
+               ret = ERR_PTR(-ENOKEY);
                goto out;
        }
 
 
        req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
        if (IS_ERR(req)) {
-               err = PTR_ERR(req);
+               ret = ERR_CAST(req);
                goto out;
        }
 
        mode |= S_IFDIR;
        req->r_new_inode = ceph_new_inode(dir, dentry, &mode, &as_ctx);
        if (IS_ERR(req->r_new_inode)) {
-               err = PTR_ERR(req->r_new_inode);
+               ret = ERR_CAST(req->r_new_inode);
                req->r_new_inode = NULL;
                goto out_req;
        }
@@ -1165,15 +1166,22 @@ static struct dentry *ceph_mkdir(struct mnt_idmap 
*idmap, struct inode *dir,
            !req->r_reply_info.head->is_target &&
            !req->r_reply_info.head->is_dentry)
                err = ceph_handle_notrace_create(dir, dentry);
+       ret = ERR_PTR(err);
 out_req:
+       if (!IS_ERR(ret) && req->r_dentry != dentry)
+               /* Some other dentry was spliced in */
+               ret = dget(req->r_dentry);
        ceph_mdsc_put_request(req);
 out:
-       if (!err)
+       if (!IS_ERR(ret)) {
+               if (ret)
+                       dentry = ret;
                ceph_init_inode_acls(d_inode(dentry), &as_ctx);
-       else
+       } else {
                d_drop(dentry);
+       }
        ceph_release_acl_sec_ctx(&as_ctx);
-       return ERR_PTR(err);
+       return ret;
 }
 
 static int ceph_link(struct dentry *old_dentry, struct inode *dir,
-- 
2.48.1