9 files changed, 30 insertions, 15 deletions

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index 3fab5b0cfc5a..b81e7ed3c902 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -47,7 +47,6 @@
 #include <linux/workqueue.h>
 #include <linux/sunrpc/rpc_pipe_fs.h>
 
-#include <linux/nfs_fs_sb.h>
 #include <linux/nfs_fs.h>
 
 #include <linux/nfs_idmap.h>
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index fda2b4966179..1a809f6f8989 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -236,6 +236,7 @@ nfs_get_root(struct super_block *sb, struct nfs_fh *rootfh, struct nfs_fsinfo *f
                 return ERR_PTR(error);
         }
 
+        server->fsid = fsinfo->fattr->fsid;
         return nfs_fhget(sb, rootfh, fsinfo->fattr);
 }
 
@@ -1493,6 +1494,7 @@ out:
  */
 static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 {
+        struct nfs_server *server;
         struct nfs_inode *nfsi = NFS_I(inode);
         loff_t cur_isize, new_isize;
         unsigned int    invalid = 0;
@@ -1511,6 +1513,12 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
         if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
                 goto out_changed;
 
+        server = NFS_SERVER(inode);
+        /* Update the fsid if and only if this is the root directory */
+        if (inode == inode->i_sb->s_root->d_inode
+                        && !nfs_fsid_equal(&server->fsid, &fattr->fsid))
+                server->fsid = fattr->fsid;
+
         /*
          * Update the read time so we don't revalidate too often.
          */
diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
index f0015fa876e1..a7ed88f97a11 100644
--- a/fs/nfs/nfs2xdr.c
+++ b/fs/nfs/nfs2xdr.c
@@ -131,7 +131,8 @@ xdr_decode_fattr(u32 *p, struct nfs_fattr *fattr)
         fattr->du.nfs2.blocksize = ntohl(*p++);
         rdev = ntohl(*p++);
         fattr->du.nfs2.blocks = ntohl(*p++);
-        fattr->fsid_u.nfs3 = ntohl(*p++);
+        fattr->fsid.major = ntohl(*p++);
+        fattr->fsid.minor = 0;
         fattr->fileid = ntohl(*p++);
         p = xdr_decode_time(p, &fattr->atime);
         p = xdr_decode_time(p, &fattr->mtime);
diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index ec233619687e..f70eee2cac05 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -166,7 +166,8 @@ xdr_decode_fattr(u32 *p, struct nfs_fattr *fattr)
         if (MAJOR(fattr->rdev) != major || MINOR(fattr->rdev) != minor)
                 fattr->rdev = 0;
 
-        p = xdr_decode_hyper(p, &fattr->fsid_u.nfs3);
+        p = xdr_decode_hyper(p, &fattr->fsid.major);
+        fattr->fsid.minor = 0;
         p = xdr_decode_hyper(p, &fattr->fileid);
         p = xdr_decode_time3(p, &fattr->atime);
         p = xdr_decode_time3(p, &fattr->mtime);
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 7e9a840057f2..0d5794675944 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -2217,7 +2217,7 @@ static int decode_attr_symlink_support(struct xdr_stream *xdr, uint32_t *bitmap,
         return 0;
 }
 
-static int decode_attr_fsid(struct xdr_stream *xdr, uint32_t *bitmap, struct nfs4_fsid *fsid)
+static int decode_attr_fsid(struct xdr_stream *xdr, uint32_t *bitmap, struct nfs_fsid *fsid)
 {
         uint32_t *p;
 
@@ -2863,7 +2863,7 @@ static int decode_getfattr(struct xdr_stream *xdr, struct nfs_fattr *fattr, cons
                 goto xdr_error;
         if ((status = decode_attr_size(xdr, bitmap, &fattr->size)) != 0)
                 goto xdr_error;
-        if ((status = decode_attr_fsid(xdr, bitmap, &fattr->fsid_u.nfs4)) != 0)
+        if ((status = decode_attr_fsid(xdr, bitmap, &fattr->fsid)) != 0)
                 goto xdr_error;
         if ((status = decode_attr_fileid(xdr, bitmap, &fattr->fileid)) != 0)
                 goto xdr_error;
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index fc48135621ed..6763a0089ee4 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -16,8 +16,6 @@
 #include <linux/rwsem.h>
 #include <linux/wait.h>
 
-#include <linux/nfs_fs_sb.h>
-
 #include <linux/sunrpc/debug.h>
 #include <linux/sunrpc/auth.h>
 #include <linux/sunrpc/clnt.h>
@@ -27,6 +25,9 @@
 #include <linux/nfs3.h>
 #include <linux/nfs4.h>
 #include <linux/nfs_xdr.h>
+
+#include <linux/nfs_fs_sb.h>
+
 #include <linux/rwsem.h>
 #include <linux/mempool.h>
 
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 65dec21af774..6b4a13c79474 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -35,6 +35,7 @@ struct nfs_server {
         char *                  hostname;       /* remote hostname */
         struct nfs_fh           fh;
         struct sockaddr_in      addr;
+        struct nfs_fsid         fsid;
         unsigned long           mount_time;     /* when this fs was mounted */
 #ifdef CONFIG_NFS_V4
         /* Our own IP address, as a null-terminated string.
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 8cadb0a77a7a..1f7bd287c230 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -13,7 +13,6 @@
 #include <linux/list.h>
 #include <linux/pagemap.h>
 #include <linux/wait.h>
-#include <linux/nfs_fs_sb.h>
 #include <linux/sunrpc/auth.h>
 #include <linux/nfs_xdr.h>
 
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index e206c07080fe..95682f7d738a 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -14,11 +14,19 @@
 #define NFS_DEF_FILE_IO_SIZE    (4096U)
 #define NFS_MIN_FILE_IO_SIZE    (1024U)
 
-struct nfs4_fsid {
-        __u64 major;
-        __u64 minor;
+struct nfs_fsid {
+        uint64_t                major;
+        uint64_t                minor;
 };
 
+/*
+ * Helper for checking equality between 2 fsids.
+ */
+static inline int nfs_fsid_equal(const struct nfs_fsid *a, const struct nfs_fsid *b)
+{
+        return a->major == b->major && a->minor == b->minor;
+}
+
 struct nfs_fattr {
         unsigned short          valid;          /* which fields are valid */
         __u64                   pre_size;       /* pre_op_attr.size       */
@@ -40,10 +48,7 @@ struct nfs_fattr {
                 } nfs3;
         } du;
         dev_t                   rdev;
-        union {
-                __u64           nfs3;           /* also nfs2 */
-                struct nfs4_fsid nfs4;
-        } fsid_u;
+        struct nfs_fsid         fsid;
         __u64                   fileid;
         struct timespec         atime;
         struct timespec         mtime;