NFSv4: Ensure we request the ordinary fileid when doing readdirplus

When readdir() returns a directory entry for the root of a mounted
filesystem, Linux follows the old convention of returning the inode
number of the covered directory (despite newer versions of POSIX declaring
that this is a bug).
To ensure this continues to work, the NFSv4 readdir implementation requests
the 'mounted-on-fileid' from the server.

However, readdirplus also needs to instantiate an inode for this entry, and
for that, we also need to request the real fileid as per this patch.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 14 insertions, 17 deletions

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index ba952bdc4d62..7310d2ec5de8 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1452,26 +1452,25 @@ static void encode_read(struct xdr_stream *xdr, const struct nfs_readargs *args,
 
 static void encode_readdir(struct xdr_stream *xdr, const struct nfs4_readdir_arg *readdir, struct rpc_rqst *req, struct compound_hdr *hdr)
 {
-        uint32_t attrs[2] = {0, 0};
+        uint32_t attrs[2] = {
+                FATTR4_WORD0_RDATTR_ERROR,
+                FATTR4_WORD1_MOUNTED_ON_FILEID,
+        };
         uint32_t dircount = readdir->count >> 1;
         __be32 *p;
 
         if (readdir->plus) {
                 attrs[0] |= FATTR4_WORD0_TYPE|FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE|
-                        FATTR4_WORD0_FSID|FATTR4_WORD0_FILEHANDLE;
+                        FATTR4_WORD0_FSID|FATTR4_WORD0_FILEHANDLE|FATTR4_WORD0_FILEID;
                 attrs[1] |= FATTR4_WORD1_MODE|FATTR4_WORD1_NUMLINKS|FATTR4_WORD1_OWNER|
                         FATTR4_WORD1_OWNER_GROUP|FATTR4_WORD1_RAWDEV|
                         FATTR4_WORD1_SPACE_USED|FATTR4_WORD1_TIME_ACCESS|
                         FATTR4_WORD1_TIME_METADATA|FATTR4_WORD1_TIME_MODIFY;
                 dircount >>= 1;
         }
-        attrs[0] |= FATTR4_WORD0_RDATTR_ERROR|FATTR4_WORD0_FILEID;
-        attrs[1] |= FATTR4_WORD1_MOUNTED_ON_FILEID;
-        /* Switch to mounted_on_fileid if the server supports it */
-        if (readdir->bitmask[1] & FATTR4_WORD1_MOUNTED_ON_FILEID)
-                attrs[0] &= ~FATTR4_WORD0_FILEID;
-        else
-                attrs[1] &= ~FATTR4_WORD1_MOUNTED_ON_FILEID;
+        /* Use mounted_on_fileid only if the server supports it */
+        if (!(readdir->bitmask[1] & FATTR4_WORD1_MOUNTED_ON_FILEID))
+                attrs[0] |= FATTR4_WORD0_FILEID;
 
         p = reserve_space(xdr, 12+NFS4_VERIFIER_SIZE+20);
         *p++ = cpu_to_be32(OP_READDIR);
@@ -3140,7 +3139,7 @@ static int decode_attr_mounted_on_fileid(struct xdr_stream *xdr, uint32_t *bitma
                         goto out_overflow;
                 xdr_decode_hyper(p, fileid);
                 bitmap[1] &= ~FATTR4_WORD1_MOUNTED_ON_FILEID;
-                ret = NFS_ATTR_FATTR_FILEID;
+                ret = NFS_ATTR_FATTR_MOUNTED_ON_FILEID;
         }
         dprintk("%s: fileid=%Lu\n", __func__, (unsigned long long)*fileid);
         return ret;
@@ -4002,7 +4001,6 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
 {
         int status;
         umode_t fmode = 0;
-        uint64_t fileid;
         uint32_t type;
 
         status = decode_attr_type(xdr, bitmap, &type);
@@ -4101,13 +4099,10 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
                 goto xdr_error;
         fattr->valid |= status;
 
-        status = decode_attr_mounted_on_fileid(xdr, bitmap, &fileid);
+        status = decode_attr_mounted_on_fileid(xdr, bitmap, &fattr->mounted_on_fileid);
         if (status < 0)
                 goto xdr_error;
-        if (status != 0 && !(fattr->valid & status)) {
-                fattr->fileid = fileid;
-                fattr->valid |= status;
-        }
+        fattr->valid |= status;
 
 xdr_error:
         dprintk("%s: xdr returned %d\n", __func__, -status);
@@ -6411,7 +6406,9 @@ int nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
         if (decode_getfattr_attrs(xdr, bitmap, entry->fattr, entry->fh,
                                         entry->server, 1) < 0)
                 goto out_overflow;
-        if (entry->fattr->valid & NFS_ATTR_FATTR_FILEID)
+        if (entry->fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID)
+                entry->ino = entry->fattr->mounted_on_fileid;
+        else if (entry->fattr->valid & NFS_ATTR_FATTR_FILEID)
                 entry->ino = entry->fattr->fileid;
 
         entry->d_type = DT_UNKNOWN;