NFS: Add a boot parameter to disable 64 bit inode numbers

This boot parameter will allow legacy 32-bit applications which call stat()
to continue to function even if the NFSv3/v4 server uses 64-bit inode
numbers.

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

4 files changed, 36 insertions, 2 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4d175c751246..83e21045114e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1073,6 +1073,13 @@ and is between 256 and 4096 characters. It is defined in the file
                         [NFS] set the maximum lifetime for idmapper cache
                         entries.
 
+        nfs.enable_ino64=
+                        [NFS] enable 64-bit inode numbers.
+                        If zero, the NFS client will fake up a 32-bit inode
+                        number for the readdir() and stat() syscalls instead
+                        of returning the full 64-bit number.
+                        The default is to return 64-bit inode numbers.
+
         nmi_watchdog=   [KNL,BUGS=X86-32] Debugging features for SMP kernels
 
         no387           [BUGS=X86-32] Tells the kernel to use the 387 maths
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index a4fdc4cc306c..8ec7fbd8240c 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -427,7 +427,8 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
                 }
 
                 res = filldir(dirent, entry->name, entry->len, 
-                              file->f_pos, fileid, d_type);
+                              file->f_pos, nfs_compat_user_ino64(fileid),
+                              d_type);
                 if (res < 0)
                         break;
                 file->f_pos++;
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index cad1246bf575..035c769b715e 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -49,6 +49,11 @@
 
 #define NFSDBG_FACILITY         NFSDBG_VFS
 
+#define NFS_64_BIT_INODE_NUMBERS_ENABLED        1
+
+/* Default is to see 64-bit inode numbers */
+static int enable_ino64 = NFS_64_BIT_INODE_NUMBERS_ENABLED;
+
 static void nfs_invalidate_inode(struct inode *);
 static int nfs_update_inode(struct inode *, struct nfs_fattr *);
 
@@ -62,6 +67,25 @@ nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
         return nfs_fileid_to_ino_t(fattr->fileid);
 }
 
+/**
+ * nfs_compat_user_ino64 - returns the user-visible inode number
+ * @fileid: 64-bit fileid
+ *
+ * This function returns a 32-bit inode number if the boot parameter
+ * nfs.enable_ino64 is zero.
+ */
+u64 nfs_compat_user_ino64(u64 fileid)
+{
+        int ino;
+
+        if (enable_ino64)
+                return fileid;
+        ino = fileid;
+        if (sizeof(ino) < sizeof(fileid))
+                ino ^= fileid >> (sizeof(fileid)-sizeof(ino)) * 8;
+        return ino;
+}
+
 int nfs_write_inode(struct inode *inode, int sync)
 {
         int ret;
@@ -456,7 +480,7 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
                 err = nfs_revalidate_inode(NFS_SERVER(inode), inode);
         if (!err) {
                 generic_fillattr(inode, stat);
-                stat->ino = NFS_FILEID(inode);
+                stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
         }
         return err;
 }
@@ -1235,6 +1259,7 @@ static void __exit exit_nfs_fs(void)
 /* Not quite true; I just maintain it */
 MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
 MODULE_LICENSE("GPL");
+module_param(enable_ino64, bool, 0644);
 
 module_init(init_nfs_fs)
 module_exit(exit_nfs_fs)
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 0e0c2e0d3aa3..c5164c257f71 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -289,6 +289,7 @@ extern void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr);
 extern struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx);
 extern void put_nfs_open_context(struct nfs_open_context *ctx);
 extern struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_cred *cred, int mode);
+extern u64 nfs_compat_user_ino64(u64 fileid);
 
 /* linux/net/ipv4/ipconfig.c: trims ip addr off front of name, too. */
 extern __be32 root_nfs_parse_addr(char *name); /*__init*/