9p: Implement TLOCK

Synopsis

    size[4] TLock tag[2] fid[4] flock[n]
    size[4] RLock tag[2] status[1]

Description

Tlock is used to acquire/release byte range posix locks on a file
identified by given fid. The reply contains status of the lock request

    flock structure:
        type[1] - Type of lock: F_RDLCK, F_WRLCK, F_UNLCK
        flags[4] - Flags could be either of
          P9_LOCK_FLAGS_BLOCK - Blocked lock request, if there is a
            conflicting lock exists, wait for that lock to be released.
          P9_LOCK_FLAGS_RECLAIM - Reclaim lock request, used when client is
            trying to reclaim a lock after a server restrart (due to crash)
        start[8] - Starting offset for lock
        length[8] - Number of bytes to lock
          If length is 0, lock all bytes starting at the location 'start'
          through to the end of file
        pid[4] - PID of the process that wants to take lock
        client_id[4] - Unique client id

        status[1] - Status of the lock request, can be
          P9_LOCK_SUCCESS(0), P9_LOCK_BLOCKED(1), P9_LOCK_ERROR(2) or
          P9_LOCK_GRACE(3)
          P9_LOCK_SUCCESS - Request was successful
          P9_LOCK_BLOCKED - A conflicting lock is held by another process
          P9_LOCK_ERROR - Error while processing the lock request
          P9_LOCK_GRACE - Server is in grace period, it can't accept new lock
            requests in this period (except locks with
            P9_LOCK_FLAGS_RECLAIM flag set)

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

2 files changed, 29 insertions, 0 deletions

diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
index 55e96057f47f..1859a2560cc5 100644
--- a/include/net/9p/9p.h
+++ b/include/net/9p/9p.h
@@ -165,6 +165,8 @@ enum p9_msg_t {
         P9_RREADDIR,
         P9_TFSYNC = 50,
         P9_RFSYNC,
+        P9_TLOCK = 52,
+        P9_RLOCK,
         P9_TLINK = 70,
         P9_RLINK,
         P9_TMKDIR = 72,
@@ -464,6 +466,32 @@ struct p9_iattr_dotl {
         u64 mtime_nsec;
 };
 
+#define P9_LOCK_SUCCESS 0
+#define P9_LOCK_BLOCKED 1
+#define P9_LOCK_ERROR 2
+#define P9_LOCK_GRACE 3
+
+#define P9_LOCK_FLAGS_BLOCK 1
+#define P9_LOCK_FLAGS_RECLAIM 2
+
+/* struct p9_flock: POSIX lock structure
+ * @type - type of lock
+ * @flags - lock flags
+ * @start - starting offset of the lock
+ * @length - number of bytes
+ * @proc_id - process id which wants to take lock
+ * @client_id - client id
+ */
+
+struct p9_flock {
+        u8 type;
+        u32 flags;
+        u64 start;
+        u64 length;
+        u32 proc_id;
+        char *client_id;
+};
+
 /* Structures for Protocol Operations */
 struct p9_tstatfs {
         u32 fid;
diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index 8744e3ad4a07..d7dcb142e3bb 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -249,6 +249,7 @@ int p9_client_mknod_dotl(struct p9_fid *oldfid, char *name, int mode,
                         dev_t rdev, gid_t gid, struct p9_qid *);
 int p9_client_mkdir_dotl(struct p9_fid *fid, char *name, int mode,
                                 gid_t gid, struct p9_qid *);
+int p9_client_lock_dotl(struct p9_fid *fid, struct p9_flock *flock, u8 *status);
 struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
 void p9_client_cb(struct p9_client *c, struct p9_req_t *req);