NFS: Simplify ->decode_dirent() calling sequence

Clean up.

The pointer returned by ->decode_dirent() is no longer used as a
pointer.  The only call site (xdr_decode() in fs/nfs/dir.c) simply
extracts the errno value encoded in the pointer.  Replace the
returned pointer with a standard integer errno return value.

Also, pass the "server" argument as part of the nfs_entry instead of
as a separate parameter.  It's faster to derive "server" in
nfs_readdir_xdr_to_array() since we already have the directory's inode
handy.  "server" ought to be invariant for a set of entries in the
same directory, right?

The legacy versions of decode_dirent() don't use "server" anyway, so
it's wasted work for them to derive and pass "server" for each entry.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

7 files changed, 61 insertions, 42 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 996dd8989a91..3e2123fe79f5 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -172,7 +172,7 @@ struct nfs_cache_array {
         struct nfs_cache_array_entry array[0];
 };
 
-typedef __be32 * (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int);
+typedef int (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, int);
 typedef struct {
         struct file     *file;
         struct page     *page;
@@ -378,14 +378,14 @@ error:
         return error;
 }
 
-/* Fill in an entry based on the xdr code stored in desc->page */
-static
-int xdr_decode(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry, struct xdr_stream *stream)
+static int xdr_decode(nfs_readdir_descriptor_t *desc,
+                      struct nfs_entry *entry, struct xdr_stream *xdr)
 {
-        __be32 *p = desc->decode(stream, entry, NFS_SERVER(desc->file->f_path.dentry->d_inode), desc->plus);
-        if (IS_ERR(p))
-                return PTR_ERR(p);
+        int error;
 
+        error = desc->decode(xdr, entry, desc->plus);
+        if (error)
+                return error;
         entry->fattr->time_start = desc->timestamp;
         entry->fattr->gencount = desc->gencount;
         return 0;
@@ -566,6 +566,7 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
         entry.eof = 0;
         entry.fh = nfs_alloc_fhandle();
         entry.fattr = nfs_alloc_fattr();
+        entry.server = NFS_SERVER(inode);
         if (entry.fh == NULL || entry.fattr == NULL)
                 goto out;
 
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 6c6a9955bae9..435eae3666bd 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -187,15 +187,18 @@ extern void nfs_destroy_directcache(void);
 /* nfs2xdr.c */
 extern int nfs_stat_to_errno(enum nfs_stat);
 extern struct rpc_procinfo nfs_procedures[];
-extern __be32 *nfs2_decode_dirent(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int);
+extern int nfs2_decode_dirent(struct xdr_stream *,
+                                struct nfs_entry *, int);
 
 /* nfs3xdr.c */
 extern struct rpc_procinfo nfs3_procedures[];
-extern __be32 *nfs3_decode_dirent(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int);
+extern int nfs3_decode_dirent(struct xdr_stream *,
+                                struct nfs_entry *, int);
 
 /* nfs4xdr.c */
 #ifdef CONFIG_NFS_V4
-extern __be32 *nfs4_decode_dirent(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int);
+extern int nfs4_decode_dirent(struct xdr_stream *,
+                                struct nfs_entry *, int);
 #endif
 #ifdef CONFIG_NFS_V4_1
 extern const u32 nfs41_maxread_overhead;
diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
index 0343175fe6c0..a9b848edbd2e 100644
--- a/fs/nfs/nfs2xdr.c
+++ b/fs/nfs/nfs2xdr.c
@@ -936,10 +936,10 @@ static int nfs2_xdr_dec_writeres(struct rpc_rqst *req, __be32 *p,
  *                      the local page cache.
  * @xdr: XDR stream where entry resides
  * @entry: buffer to fill in with entry data
- * @server: nfs_server data for this directory
  * @plus: boolean indicating whether this should be a readdirplus entry
  *
- * Returns the position of the next item in the buffer, or an ERR_PTR.
+ * Returns zero if successful, otherwise a negative errno value is
+ * returned.
  *
  * This function is not invoked during READDIR reply decoding, but
  * rather whenever an application invokes the getdents(2) system call
@@ -954,8 +954,8 @@ static int nfs2_xdr_dec_writeres(struct rpc_rqst *req, __be32 *p,
  *              entry           *nextentry;
  *      };
  */
-__be32 *nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
-                           struct nfs_server *server, int plus)
+int nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
+                       int plus)
 {
         __be32 *p;
         int error;
@@ -968,9 +968,9 @@ __be32 *nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
                 if (unlikely(p == NULL))
                         goto out_overflow;
                 if (*p++ == xdr_zero)
-                        return ERR_PTR(-EAGAIN);
+                        return -EAGAIN;
                 entry->eof = 1;
-                return ERR_PTR(-EBADCOOKIE);
+                return -EBADCOOKIE;
         }
 
         p = xdr_inline_decode(xdr, 4);
@@ -980,7 +980,7 @@ __be32 *nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
 
         error = decode_filename_inline(xdr, &entry->name, &entry->len);
         if (unlikely(error))
-                return ERR_PTR(error);
+                return error;
 
         /*
          * The type (size and byte order) of nfscookie isn't defined in
@@ -999,11 +999,11 @@ __be32 *nfs2_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
         entry->eof = 0;
         if (p != NULL)
                 entry->eof = (p[0] == xdr_zero) && (p[1] != xdr_zero);
-        return p;
+        return 0;
 
 out_overflow:
         print_overflow_msg(__func__, xdr);
-        return ERR_PTR(-EAGAIN);
+        return -EAGAIN;
 }
 
 /*
diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index c97d00fe849a..15c93ccd90c5 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -1970,10 +1970,10 @@ out_status:
  *                      the local page cache
  * @xdr: XDR stream where entry resides
  * @entry: buffer to fill in with entry data
- * @server: nfs_server data for this directory
  * @plus: boolean indicating whether this should be a readdirplus entry
  *
- * Returns the position of the next item in the buffer, or an ERR_PTR.
+ * Returns zero if successful, otherwise a negative errno value is
+ * returned.
  *
  * This function is not invoked during READDIR reply decoding, but
  * rather whenever an application invokes the getdents(2) system call
@@ -2000,8 +2000,8 @@ out_status:
  *              entryplus3      *nextentry;
  *      };
  */
-__be32 *nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
-                           struct nfs_server *server, int plus)
+int nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
+                       int plus)
 {
         struct nfs_entry old = *entry;
         __be32 *p;
@@ -2015,23 +2015,23 @@ __be32 *nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
                 if (unlikely(p == NULL))
                         goto out_overflow;
                 if (*p == xdr_zero)
-                        return ERR_PTR(-EAGAIN);
+                        return -EAGAIN;
                 entry->eof = 1;
-                return ERR_PTR(-EBADCOOKIE);
+                return -EBADCOOKIE;
         }
 
         error = decode_fileid3(xdr, &entry->ino);
         if (unlikely(error))
-                return ERR_PTR(error);
+                return error;
 
         error = decode_inline_filename3(xdr, &entry->name, &entry->len);
         if (unlikely(error))
-                return ERR_PTR(error);
+                return error;
 
         entry->prev_cookie = entry->cookie;
         error = decode_cookie3(xdr, &entry->cookie);
         if (unlikely(error))
-                return ERR_PTR(error);
+                return error;
 
         entry->d_type = DT_UNKNOWN;
 
@@ -2039,7 +2039,7 @@ __be32 *nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
                 entry->fattr->valid = 0;
                 error = decode_post_op_attr(xdr, entry->fattr);
                 if (unlikely(error))
-                        return ERR_PTR(error);
+                        return error;
                 if (entry->fattr->valid & NFS_ATTR_FATTR_V3)
                         entry->d_type = nfs_umode_to_dtype(entry->fattr->mode);
 
@@ -2052,7 +2052,7 @@ __be32 *nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
                         if (unlikely(error)) {
                                 if (error == -E2BIG)
                                         goto out_truncated;
-                                return ERR_PTR(error);
+                                return error;
                         }
                 } else
                         zero_nfs_fh3(entry->fh);
@@ -2063,15 +2063,15 @@ __be32 *nfs3_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
         entry->eof = 0;
         if (p != NULL)
                 entry->eof = (p[0] == xdr_zero) && (p[1] != xdr_zero);
-        return p;
+        return 0;
 
 out_overflow:
         print_overflow_msg(__func__, xdr);
-        return ERR_PTR(-EAGAIN);
+        return -EAGAIN;
 out_truncated:
         dprintk("NFS: directory entry contains invalid file handle\n");
         *entry = old;
-        return ERR_PTR(-EAGAIN);
+        return -EAGAIN;
 }
 
 /*
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 9fa496387fdf..7a6eecffcaeb 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -331,7 +331,6 @@ extern void nfs_free_seqid(struct nfs_seqid *seqid);
 extern const nfs4_stateid zero_stateid;
 
 /* nfs4xdr.c */
-extern __be32 *nfs4_decode_dirent(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int);
 extern struct rpc_procinfo nfs4_procedures[];
 
 struct nfs4_mount_data;
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 868815c55450..be9f00ab0d18 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -6159,8 +6159,22 @@ out:
 }
 #endif /* CONFIG_NFS_V4_1 */
 
-__be32 *nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
-                           struct nfs_server *server, int plus)
+/**
+ * nfs4_decode_dirent - Decode a single NFSv4 directory entry stored in
+ *                      the local page cache.
+ * @xdr: XDR stream where entry resides
+ * @entry: buffer to fill in with entry data
+ * @plus: boolean indicating whether this should be a readdirplus entry
+ *
+ * Returns zero if successful, otherwise a negative errno value is
+ * returned.
+ *
+ * This function is not invoked during READDIR reply decoding, but
+ * rather whenever an application invokes the getdents(2) system call
+ * on a directory already in our cache.
+ */
+int nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
+                       int plus)
 {
         uint32_t bitmap[2] = {0};
         uint32_t len;
@@ -6172,9 +6186,9 @@ __be32 *nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
                 if (unlikely(!p))
                         goto out_overflow;
                 if (!ntohl(*p++))
-                        return ERR_PTR(-EAGAIN);
+                        return -EAGAIN;
                 entry->eof = 1;
-                return ERR_PTR(-EBADCOOKIE);
+                return -EBADCOOKIE;
         }
 
         p = xdr_inline_decode(xdr, 12);
@@ -6203,7 +6217,8 @@ __be32 *nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
         if (decode_attr_length(xdr, &len, &p) < 0)
                 goto out_overflow;
 
-        if (decode_getfattr_attrs(xdr, bitmap, entry->fattr, entry->fh, server, 1) < 0)
+        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)
                 entry->ino = entry->fattr->fileid;
@@ -6221,11 +6236,11 @@ __be32 *nfs4_decode_dirent(struct xdr_stream *xdr, struct nfs_entry *entry,
         else
                 entry->eof = 0;
 
-        return p;
+        return 0;
 
 out_overflow:
         print_overflow_msg(__func__, xdr);
-        return ERR_PTR(-EAGAIN);
+        return -EAGAIN;
 }
 
 /*
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 80f07198a31a..236e7e4b99a0 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -484,6 +484,7 @@ struct nfs_entry {
         struct nfs_fh *         fh;
         struct nfs_fattr *      fattr;
         unsigned char           d_type;
+        struct nfs_server *     server;
 };
 
 /*
@@ -1089,7 +1090,7 @@ struct nfs_rpc_ops {
         int     (*pathconf) (struct nfs_server *, struct nfs_fh *,
                              struct nfs_pathconf *);
         int     (*set_capabilities)(struct nfs_server *, struct nfs_fh *);
-        __be32 *(*decode_dirent)(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int plus);
+        int     (*decode_dirent)(struct xdr_stream *, struct nfs_entry *, int);
         void    (*read_setup)   (struct nfs_read_data *, struct rpc_message *);
         int     (*read_done)  (struct rpc_task *, struct nfs_read_data *);
         void    (*write_setup)  (struct nfs_write_data *, struct rpc_message *);