9p: Implement TGETLOCK

Synopsis

    size[4] TGetlock tag[2] fid[4] getlock[n]
    size[4] RGetlock tag[2] getlock[n]

Description

TGetlock is used to test for the existence of byte range posix locks on a file
identified by given fid. The reply contains getlock structure. If the lock could
be placed it returns F_UNLCK in type field of getlock structure.  Otherwise it
returns the details of the conflicting locks in the getlock structure

    getlock structure:
      type[1] - Type of lock: F_RDLCK, F_WRLCK
      start[8] - Starting offset for lock
      length[8] - Number of bytes to check for the lock
             If length is 0, check for lock in all bytes starting at the location
            'start' through to the end of file
      pid[4] - PID of the process that wants to take lock/owns the task
               in case of reply
      client[4] - Client id of the system that owns the process which
                  has the conflicting lock

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>

1 files changed, 47 insertions, 0 deletions

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 6f77abd23184..3a4352f23a98 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -211,6 +211,51 @@ out:
         return res;
 }
 
+static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
+{
+        struct p9_getlock glock;
+        struct p9_fid *fid;
+        int res = 0;
+
+        fid = filp->private_data;
+        BUG_ON(fid == NULL);
+
+        posix_test_lock(filp, fl);
+        /*
+         * if we have a conflicting lock locally, no need to validate
+         * with server
+         */
+        if (fl->fl_type != F_UNLCK)
+                return res;
+
+        /* convert posix lock to p9 tgetlock args */
+        memset(&glock, 0, sizeof(glock));
+        glock.type = fl->fl_type;
+        glock.start = fl->fl_start;
+        if (fl->fl_end == OFFSET_MAX)
+                glock.length = 0;
+        else
+                glock.length = fl->fl_end - fl->fl_start + 1;
+        glock.proc_id = fl->fl_pid;
+        glock.client_id = utsname()->nodename;
+
+        res = p9_client_getlock_dotl(fid, &glock);
+        if (res < 0)
+                return res;
+        if (glock.type != F_UNLCK) {
+                fl->fl_type = glock.type;
+                fl->fl_start = glock.start;
+                if (glock.length == 0)
+                        fl->fl_end = OFFSET_MAX;
+                else
+                        fl->fl_end = glock.start + glock.length - 1;
+                fl->fl_pid = glock.proc_id;
+        } else
+                fl->fl_type = F_UNLCK;
+
+        return res;
+}
+
 /**
  * v9fs_file_lock_dotl - lock a file (or directory)
  * @filp: file to be locked
@@ -238,6 +283,8 @@ static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
 
         if (IS_SETLK(cmd) || IS_SETLKW(cmd))
                 ret = v9fs_file_do_lock(filp, cmd, fl);
+        else if (IS_GETLK(cmd))
+                ret = v9fs_file_getlock(filp, fl);
         else
                 ret = -EINVAL;
 out_err: