NFSv4: Add 'server capability' flags for NFSv4 recommended attributes

If the NFSv4 server doesn't support a POSIX attribute, the generic NFS code
needs to know that, so that it don't keep trying to poll for it.

However, by the same count, if the NFSv4 server does support that
attribute, then we should ensure that the inode metadata is appropriately
labelled as being untrusted. For instance, if we don't know the correct
value of the file's uid, we should certainly not be caching ACLs or ACCESS
results.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 8d25ccb..8f34fd8 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -809,6 +809,9 @@
 	/* Initialise the client representation from the mount data */
 	server->flags = data->flags;
 	server->options = data->options;
+	server->caps |= NFS_CAP_HARDLINKS|NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
+		NFS_CAP_MODE|NFS_CAP_NLINK|NFS_CAP_OWNER|NFS_CAP_OWNER_GROUP|
+		NFS_CAP_ATIME|NFS_CAP_CTIME|NFS_CAP_MTIME;
 
 	if (data->rsize)
 		server->rsize = nfs_block_size(data->rsize, NULL);
@@ -1274,7 +1277,7 @@
 
 	/* Initialise the client representation from the mount data */
 	server->flags = data->flags;
-	server->caps |= NFS_CAP_ATOMIC_OPEN;
+	server->caps |= NFS_CAP_ATOMIC_OPEN|NFS_CAP_CHANGE_ATTR;
 	server->options = data->options;
 
 	/* Get a client record */
@@ -1400,7 +1403,7 @@
 
 	/* Initialise the client representation from the parent server */
 	nfs_server_copy_userdata(server, parent_server);
-	server->caps |= NFS_CAP_ATOMIC_OPEN;
+	server->caps |= NFS_CAP_ATOMIC_OPEN|NFS_CAP_CHANGE_ATTR;
 
 	/* Get a client representation.
 	 * Note: NFSv4 always uses TCP, */
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index bd7938e..fe5a8b4 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -286,6 +286,11 @@
 		/* We can't support update_atime(), since the server will reset it */
 		inode->i_flags |= S_NOATIME|S_NOCMTIME;
 		inode->i_mode = fattr->mode;
+		if ((fattr->valid & NFS_ATTR_FATTR_MODE) == 0
+				&& nfs_server_capable(inode, NFS_CAP_MODE))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL;
 		/* Why so? Because we want revalidate for devices/FIFOs, and
 		 * that's precisely what we have in nfs_file_inode_operations.
 		 */
@@ -330,20 +335,46 @@
 		nfsi->attr_gencount = fattr->gencount;
 		if (fattr->valid & NFS_ATTR_FATTR_ATIME)
 			inode->i_atime = fattr->atime;
+		else if (nfs_server_capable(inode, NFS_CAP_ATIME))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
 		if (fattr->valid & NFS_ATTR_FATTR_MTIME)
 			inode->i_mtime = fattr->mtime;
+		else if (nfs_server_capable(inode, NFS_CAP_MTIME))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_DATA;
 		if (fattr->valid & NFS_ATTR_FATTR_CTIME)
 			inode->i_ctime = fattr->ctime;
+		else if (nfs_server_capable(inode, NFS_CAP_CTIME))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL;
 		if (fattr->valid & NFS_ATTR_FATTR_CHANGE)
 			nfsi->change_attr = fattr->change_attr;
+		else if (nfs_server_capable(inode, NFS_CAP_CHANGE_ATTR))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_DATA;
 		if (fattr->valid & NFS_ATTR_FATTR_SIZE)
 			inode->i_size = nfs_size_to_loff_t(fattr->size);
+		else
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_DATA
+				| NFS_INO_REVAL_PAGECACHE;
 		if (fattr->valid & NFS_ATTR_FATTR_NLINK)
 			inode->i_nlink = fattr->nlink;
+		else if (nfs_server_capable(inode, NFS_CAP_NLINK))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
 		if (fattr->valid & NFS_ATTR_FATTR_OWNER)
 			inode->i_uid = fattr->uid;
+		else if (nfs_server_capable(inode, NFS_CAP_OWNER))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL;
 		if (fattr->valid & NFS_ATTR_FATTR_GROUP)
 			inode->i_gid = fattr->gid;
+		else if (nfs_server_capable(inode, NFS_CAP_OWNER_GROUP))
+			nfsi->cache_validity |= NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL;
 		if (fattr->valid & NFS_ATTR_FATTR_BLOCKS_USED)
 			inode->i_blocks = fattr->du.nfs2.blocks;
 		if (fattr->valid & NFS_ATTR_FATTR_SPACE_USED) {
@@ -1145,6 +1176,7 @@
 	loff_t cur_isize, new_isize;
 	unsigned long invalid = 0;
 	unsigned long now = jiffies;
+	unsigned long save_cache_validity;
 
 	dfprintk(VFS, "NFS: %s(%s/%ld ct=%d info=0x%x)\n",
 			__func__, inode->i_sb->s_id, inode->i_ino,
@@ -1171,10 +1203,11 @@
 	 */
 	nfsi->read_cache_jiffies = fattr->time_start;
 
-	if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) || (fattr->valid & (NFS_ATTR_FATTR_MTIME|NFS_ATTR_FATTR_CTIME)))
-	    nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR
-		    | NFS_INO_INVALID_ATIME
-		    | NFS_INO_REVAL_PAGECACHE);
+	save_cache_validity = nfsi->cache_validity;
+	nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR
+			| NFS_INO_INVALID_ATIME
+			| NFS_INO_REVAL_FORCED
+			| NFS_INO_REVAL_PAGECACHE);
 
 	/* Do atomic weak cache consistency updates */
 	nfs_wcc_update_inode(inode, fattr);
@@ -1189,7 +1222,8 @@
 				nfs_force_lookup_revalidate(inode);
 			nfsi->change_attr = fattr->change_attr;
 		}
-	}
+	} else if (server->caps & NFS_CAP_CHANGE_ATTR)
+		invalid |= save_cache_validity;
 
 	if (fattr->valid & NFS_ATTR_FATTR_MTIME) {
 		/* NFSv2/v3: Check if the mtime agrees */
@@ -1201,7 +1235,12 @@
 				nfs_force_lookup_revalidate(inode);
 			memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
 		}
-	}
+	} else if (server->caps & NFS_CAP_MTIME)
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_DATA
+				| NFS_INO_REVAL_PAGECACHE
+				| NFS_INO_REVAL_FORCED);
+
 	if (fattr->valid & NFS_ATTR_FATTR_CTIME) {
 		/* If ctime has changed we should definitely clear access+acl caches */
 		if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) {
@@ -1215,7 +1254,11 @@
 			}
 			memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
 		}
-	}
+	} else if (server->caps & NFS_CAP_CTIME)
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL
+				| NFS_INO_REVAL_FORCED);
 
 	/* Check if our cached file size is stale */
 	if (fattr->valid & NFS_ATTR_FATTR_SIZE) {
@@ -1231,30 +1274,50 @@
 			dprintk("NFS: isize change on server for file %s/%ld\n",
 					inode->i_sb->s_id, inode->i_ino);
 		}
-	}
+	} else
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
+				| NFS_INO_REVAL_PAGECACHE
+				| NFS_INO_REVAL_FORCED);
 
 
 	if (fattr->valid & NFS_ATTR_FATTR_ATIME)
 		memcpy(&inode->i_atime, &fattr->atime, sizeof(inode->i_atime));
+	else if (server->caps & NFS_CAP_ATIME)
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATIME
+				| NFS_INO_REVAL_FORCED);
 
 	if (fattr->valid & NFS_ATTR_FATTR_MODE) {
 		if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO)) {
 			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
 			inode->i_mode = fattr->mode;
 		}
-	}
+	} else if (server->caps & NFS_CAP_MODE)
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL
+				| NFS_INO_REVAL_FORCED);
+
 	if (fattr->valid & NFS_ATTR_FATTR_OWNER) {
 		if (inode->i_uid != fattr->uid) {
 			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
 			inode->i_uid = fattr->uid;
 		}
-	}
+	} else if (server->caps & NFS_CAP_OWNER)
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL
+				| NFS_INO_REVAL_FORCED);
+
 	if (fattr->valid & NFS_ATTR_FATTR_GROUP) {
 		if (inode->i_gid != fattr->gid) {
 			invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
 			inode->i_gid = fattr->gid;
 		}
-	}
+	} else if (server->caps & NFS_CAP_OWNER_GROUP)
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
+				| NFS_INO_INVALID_ACCESS
+				| NFS_INO_INVALID_ACL
+				| NFS_INO_REVAL_FORCED);
 
 	if (fattr->valid & NFS_ATTR_FATTR_NLINK) {
 		if (inode->i_nlink != fattr->nlink) {
@@ -1263,7 +1326,9 @@
 				invalid |= NFS_INO_INVALID_DATA;
 			inode->i_nlink = fattr->nlink;
 		}
-	}
+	} else if (server->caps & NFS_CAP_NLINK)
+		invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
+				| NFS_INO_REVAL_FORCED);
 
 	if (fattr->valid & NFS_ATTR_FATTR_SPACE_USED) {
 		/*
@@ -1293,9 +1358,8 @@
 				|| S_ISLNK(inode->i_mode)))
 		invalid &= ~NFS_INO_INVALID_DATA;
 	if (!nfs_have_delegation(inode, FMODE_READ) ||
-			(nfsi->cache_validity & NFS_INO_REVAL_FORCED))
+			(save_cache_validity & NFS_INO_REVAL_FORCED))
 		nfsi->cache_validity |= invalid;
-	nfsi->cache_validity &= ~NFS_INO_REVAL_FORCED;
 
 	return 0;
  out_changed:
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index d95f7f9..be6544a 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2003,12 +2003,34 @@
 	status = nfs4_call_sync(server, &msg, &args, &res, 0);
 	if (status == 0) {
 		memcpy(server->attr_bitmask, res.attr_bitmask, sizeof(server->attr_bitmask));
+		server->caps &= ~(NFS_CAP_ACLS|NFS_CAP_HARDLINKS|
+				NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
+				NFS_CAP_MODE|NFS_CAP_NLINK|NFS_CAP_OWNER|
+				NFS_CAP_OWNER_GROUP|NFS_CAP_ATIME|
+				NFS_CAP_CTIME|NFS_CAP_MTIME);
 		if (res.attr_bitmask[0] & FATTR4_WORD0_ACL)
 			server->caps |= NFS_CAP_ACLS;
 		if (res.has_links != 0)
 			server->caps |= NFS_CAP_HARDLINKS;
 		if (res.has_symlinks != 0)
 			server->caps |= NFS_CAP_SYMLINKS;
+		if (res.attr_bitmask[0] & FATTR4_WORD0_FILEID)
+			server->caps |= NFS_CAP_FILEID;
+		if (res.attr_bitmask[1] & FATTR4_WORD1_MODE)
+			server->caps |= NFS_CAP_MODE;
+		if (res.attr_bitmask[1] & FATTR4_WORD1_NUMLINKS)
+			server->caps |= NFS_CAP_NLINK;
+		if (res.attr_bitmask[1] & FATTR4_WORD1_OWNER)
+			server->caps |= NFS_CAP_OWNER;
+		if (res.attr_bitmask[1] & FATTR4_WORD1_OWNER_GROUP)
+			server->caps |= NFS_CAP_OWNER_GROUP;
+		if (res.attr_bitmask[1] & FATTR4_WORD1_TIME_ACCESS)
+			server->caps |= NFS_CAP_ATIME;
+		if (res.attr_bitmask[1] & FATTR4_WORD1_TIME_METADATA)
+			server->caps |= NFS_CAP_CTIME;
+		if (res.attr_bitmask[1] & FATTR4_WORD1_TIME_MODIFY)
+			server->caps |= NFS_CAP_MTIME;
+
 		memcpy(server->cache_consistency_bitmask, res.attr_bitmask, sizeof(server->cache_consistency_bitmask));
 		server->cache_consistency_bitmask[0] &= FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE;
 		server->cache_consistency_bitmask[1] &= FATTR4_WORD1_TIME_METADATA|FATTR4_WORD1_TIME_MODIFY;
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 19fe15d..320569e 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -167,6 +167,15 @@
 #define NFS_CAP_SYMLINKS	(1U << 2)
 #define NFS_CAP_ACLS		(1U << 3)
 #define NFS_CAP_ATOMIC_OPEN	(1U << 4)
+#define NFS_CAP_CHANGE_ATTR	(1U << 5)
+#define NFS_CAP_FILEID		(1U << 6)
+#define NFS_CAP_MODE		(1U << 7)
+#define NFS_CAP_NLINK		(1U << 8)
+#define NFS_CAP_OWNER		(1U << 9)
+#define NFS_CAP_OWNER_GROUP	(1U << 10)
+#define NFS_CAP_ATIME		(1U << 11)
+#define NFS_CAP_CTIME		(1U << 12)
+#define NFS_CAP_MTIME		(1U << 13)
 
 
 /* maximum number of slots to use */