orangefs: add features op

This is a new userspace operation, which will be done if the client-core
version is greater than or equal to 2.9.6. This will provide a way to
implement optional features and to determine which features are
supported by the client-core. If the client-core version is older than
2.9.6, no optional features are supported and the op will not be done.

The intent is to allow protocol extensions without relying on the
client-core's current behavior of ignoring what it doesn't understand.

Signed-off-by: Martin Brandenburg <martin@omnibond.com>

7 files changed, 53 insertions, 6 deletions

diff --git a/fs/orangefs/devorangefs-req.c b/fs/orangefs/devorangefs-req.c
index 7c40e653e526..ec1a5ff1d843 100644
--- a/fs/orangefs/devorangefs-req.c
+++ b/fs/orangefs/devorangefs-req.c
@@ -17,7 +17,7 @@
 
 /* this file implements the /dev/pvfs2-req device node */
 
-uint32_t userspace_version;
+uint32_t orangefs_userspace_version;
 
 static int open_access_count;
 
@@ -389,9 +389,9 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
                 return -EPROTO;
         }
 
-        if (!userspace_version) {
-                userspace_version = head.version;
-        } else if (userspace_version != head.version) {
+        if (!orangefs_userspace_version) {
+                orangefs_userspace_version = head.version;
+        } else if (orangefs_userspace_version != head.version) {
                 gossip_err("Error: userspace version changes\n");
                 return -EPROTO;
         }
@@ -536,7 +536,7 @@ static int orangefs_devreq_release(struct inode *inode, struct file *file)
         gossip_debug(GOSSIP_DEV_DEBUG,
                      "pvfs2-client-core: device close complete\n");
         open_access_count = 0;
-        userspace_version = 0;
+        orangefs_userspace_version = 0;
         mutex_unlock(&devreq_mutex);
         return 0;
 }
diff --git a/fs/orangefs/downcall.h b/fs/orangefs/downcall.h
index db6e8722a89e..3b8923f8bf21 100644
--- a/fs/orangefs/downcall.h
+++ b/fs/orangefs/downcall.h
@@ -101,6 +101,11 @@ struct orangefs_fs_key_response {
         char fs_key[FS_KEY_BUF_SIZE];
 };
 
+/* 2.9.6 */
+struct orangefs_features_response {
+        __u64 features;
+};
+
 struct orangefs_downcall_s {
         __s32 type;
         __s32 status;
@@ -122,6 +127,7 @@ struct orangefs_downcall_s {
                 struct orangefs_param_response param;
                 struct orangefs_perf_count_response perf_count;
                 struct orangefs_fs_key_response fs_key;
+                struct orangefs_features_response features;
         } resp;
 };
 
diff --git a/fs/orangefs/orangefs-cache.c b/fs/orangefs/orangefs-cache.c
index eb0b6e00b519..aa3830b741c7 100644
--- a/fs/orangefs/orangefs-cache.c
+++ b/fs/orangefs/orangefs-cache.c
@@ -97,6 +97,8 @@ char *get_opname_string(struct orangefs_kernel_op_s *new_op)
                         return "OP_FSYNC";
                 else if (type == ORANGEFS_VFS_OP_FSKEY)
                         return "OP_FSKEY";
+                else if (type == ORANGEFS_VFS_OP_FEATURES)
+                        return "OP_FEATURES";
         }
         return "OP_UNKNOWN?";
 }
diff --git a/fs/orangefs/orangefs-dev-proto.h b/fs/orangefs/orangefs-dev-proto.h
index 71902899b1da..a3d84ffee905 100644
--- a/fs/orangefs/orangefs-dev-proto.h
+++ b/fs/orangefs/orangefs-dev-proto.h
@@ -41,6 +41,10 @@
 #define ORANGEFS_VFS_OP_FSYNC          0xFF00EE01
 #define ORANGEFS_VFS_OP_FSKEY             0xFF00EE02
 #define ORANGEFS_VFS_OP_READDIRPLUS       0xFF00EE03
+#define ORANGEFS_VFS_OP_FEATURES        0xFF00EE05 /* 2.9.6 */
+
+/* features is a 64-bit unsigned bitmask */
+#define ORANGEFS_FEATURE_READAHEAD 1
 
 /*
  * Misc constants. Please retain them as multiples of 8!
diff --git a/fs/orangefs/orangefs-kernel.h b/fs/orangefs/orangefs-kernel.h
index ff3566a8388f..6cf3f467fd89 100644
--- a/fs/orangefs/orangefs-kernel.h
+++ b/fs/orangefs/orangefs-kernel.h
@@ -447,6 +447,8 @@ void purge_waiting_ops(void);
 /*
  * defined in super.c
  */
+extern uint64_t orangefs_features;
+
 struct dentry *orangefs_mount(struct file_system_type *fst,
                            int flags,
                            const char *devname,
@@ -506,7 +508,7 @@ ssize_t orangefs_inode_read(struct inode *inode,
 /*
  * defined in devorangefs-req.c
  */
-extern uint32_t userspace_version;
+extern uint32_t orangefs_userspace_version;
 
 int orangefs_dev_init(void);
 void orangefs_dev_cleanup(void);
diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index b9da9a0281c9..3e484a667340 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -33,6 +33,7 @@ static const match_table_t tokens = {
         { Opt_err,      NULL }
 };
 
+uint64_t orangefs_features;
 
 static int parse_mount_options(struct super_block *sb, char *options,
                 int silent)
@@ -249,6 +250,19 @@ int orangefs_remount(struct orangefs_sb_info_s *orangefs_sb)
         }
 
         op_release(new_op);
+
+        if (orangefs_userspace_version >= 20906) {
+                new_op = op_alloc(ORANGEFS_VFS_OP_FEATURES);
+                if (!new_op)
+                        return -ENOMEM;
+                new_op->upcall.req.features.features = 0;
+                ret = service_operation(new_op, "orangefs_features", 0);
+                orangefs_features = new_op->downcall.resp.features.features;
+                op_release(new_op);
+        } else {
+                orangefs_features = 0;
+        }
+
         return ret;
 }
 
@@ -492,6 +506,19 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
         list_add_tail(&ORANGEFS_SB(sb)->list, &orangefs_superblocks);
         spin_unlock(&orangefs_superblocks_lock);
         op_release(new_op);
+
+        if (orangefs_userspace_version >= 20906) {
+                new_op = op_alloc(ORANGEFS_VFS_OP_FEATURES);
+                if (!new_op)
+                        return ERR_PTR(-ENOMEM);
+                new_op->upcall.req.features.features = 0;
+                ret = service_operation(new_op, "orangefs_features", 0);
+                orangefs_features = new_op->downcall.resp.features.features;
+                op_release(new_op);
+        } else {
+                orangefs_features = 0;
+        }
+
         return dget(sb->s_root);
 
 free_op:
diff --git a/fs/orangefs/upcall.h b/fs/orangefs/upcall.h
index 7c29fdf08ec5..af0b0e36d559 100644
--- a/fs/orangefs/upcall.h
+++ b/fs/orangefs/upcall.h
@@ -210,6 +210,11 @@ struct orangefs_fs_key_request_s {
         __s32 __pad1;
 };
 
+/* 2.9.6 */
+struct orangefs_features_request_s {
+        __u64 features;
+};
+
 struct orangefs_upcall_s {
         __s32 type;
         __u32 uid;
@@ -246,6 +251,7 @@ struct orangefs_upcall_s {
                 struct orangefs_param_request_s param;
                 struct orangefs_perf_count_request_s perf_count;
                 struct orangefs_fs_key_request_s fs_key;
+                struct orangefs_features_request_s features;
         } req;
 };