[DLM] dlm_device interface changes [3/6]

Change the user/kernel device interface used by libdlm:
- Add ability for userspace to check the version of the interface.  libdlm
  can now adapt to different versions of the kernel interface.
- Increase the size of the flags passed in a lock request so all possible
  flags can be used from userspace.
- Add an opaque "xid" value for each lock.  This "transaction id" will be
  used later to associate locks with each other during deadlock detection.
- Add a "timeout" value for each lock.  This is used along with the
  DLM_LKF_TIMEOUT flag.

Also, remove a fragment of unused code in device_read().

This patch requires updating libdlm which is backward compatible with
older kernels.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 43 insertions, 10 deletions

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index c7612da5b617..37aad3fe8949 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -33,16 +33,17 @@ static const struct file_operations device_fops;
 struct dlm_lock_params32 {
         __u8 mode;
         __u8 namelen;
-        __u16 flags;
+        __u16 unused;
+        __u32 flags;
         __u32 lkid;
         __u32 parent;
-
+        __u64 xid;
+        __u64 timeout;
         __u32 castparam;
         __u32 castaddr;
         __u32 bastparam;
         __u32 bastaddr;
         __u32 lksb;
-
         char lvb[DLM_USER_LVB_LEN];
         char name[0];
 };
@@ -68,6 +69,7 @@ struct dlm_lksb32 {
 };
 
 struct dlm_lock_result32 {
+        __u32 version[3];
         __u32 length;
         __u32 user_astaddr;
         __u32 user_astparam;
@@ -102,6 +104,8 @@ static void compat_input(struct dlm_write_request *kb,
                 kb->i.lock.flags = kb32->i.lock.flags;
                 kb->i.lock.lkid = kb32->i.lock.lkid;
                 kb->i.lock.parent = kb32->i.lock.parent;
+                kb->i.lock.xid = kb32->i.lock.xid;
+                kb->i.lock.timeout = kb32->i.lock.timeout;
                 kb->i.lock.castparam = (void *)(long)kb32->i.lock.castparam;
                 kb->i.lock.castaddr = (void *)(long)kb32->i.lock.castaddr;
                 kb->i.lock.bastparam = (void *)(long)kb32->i.lock.bastparam;
@@ -115,6 +119,10 @@ static void compat_input(struct dlm_write_request *kb,
 static void compat_output(struct dlm_lock_result *res,
                           struct dlm_lock_result32 *res32)
 {
+        res32->version[0] = res->version[0];
+        res32->version[1] = res->version[1];
+        res32->version[2] = res->version[2];
+
         res32->user_astaddr = (__u32)(long)res->user_astaddr;
         res32->user_astparam = (__u32)(long)res->user_astparam;
         res32->user_lksb = (__u32)(long)res->user_lksb;
@@ -252,16 +260,18 @@ static int device_user_lock(struct dlm_user_proc *proc,
         ua->castaddr = params->castaddr;
         ua->bastparam = params->bastparam;
         ua->bastaddr = params->bastaddr;
+        ua->xid = params->xid;
 
         if (params->flags & DLM_LKF_CONVERT)
                 error = dlm_user_convert(ls, ua,
                                          params->mode, params->flags,
-                                         params->lkid, params->lvb);
+                                         params->lkid, params->lvb,
+                                         (unsigned long) params->timeout);
         else {
                 error = dlm_user_request(ls, ua,
                                          params->mode, params->flags,
                                          params->name, params->namelen,
-                                         params->parent);
+                                         (unsigned long) params->timeout);
                 if (!error)
                         error = ua->lksb.sb_lkid;
         }
@@ -641,6 +651,9 @@ static int copy_result_to_user(struct dlm_user_args *ua, int compat, int type,
         int struct_len;
 
         memset(&result, 0, sizeof(struct dlm_lock_result));
+        result.version[0] = DLM_DEVICE_VERSION_MAJOR;
+        result.version[1] = DLM_DEVICE_VERSION_MINOR;
+        result.version[2] = DLM_DEVICE_VERSION_PATCH;
         memcpy(&result.lksb, &ua->lksb, sizeof(struct dlm_lksb));
         result.user_lksb = ua->user_lksb;
 
@@ -699,6 +712,20 @@ static int copy_result_to_user(struct dlm_user_args *ua, int compat, int type,
         return error;
 }
 
+static int copy_version_to_user(char __user *buf, size_t count)
+{
+        struct dlm_device_version ver;
+
+        memset(&ver, 0, sizeof(struct dlm_device_version));
+        ver.version[0] = DLM_DEVICE_VERSION_MAJOR;
+        ver.version[1] = DLM_DEVICE_VERSION_MINOR;
+        ver.version[2] = DLM_DEVICE_VERSION_PATCH;
+
+        if (copy_to_user(buf, &ver, sizeof(struct dlm_device_version)))
+                return -EFAULT;
+        return sizeof(struct dlm_device_version);
+}
+
 /* a read returns a single ast described in a struct dlm_lock_result */
 
 static ssize_t device_read(struct file *file, char __user *buf, size_t count,
@@ -710,6 +737,16 @@ static ssize_t device_read(struct file *file, char __user *buf, size_t count,
         DECLARE_WAITQUEUE(wait, current);
         int error, type=0, bmode=0, removed = 0;
 
+        if (count == sizeof(struct dlm_device_version)) {
+                error = copy_version_to_user(buf, count);
+                return error;
+        }
+
+        if (!proc) {
+                log_print("non-version read from control device %zu", count);
+                return -EINVAL;
+        }
+
 #ifdef CONFIG_COMPAT
         if (count < sizeof(struct dlm_lock_result32))
 #else
@@ -747,11 +784,6 @@ static ssize_t device_read(struct file *file, char __user *buf, size_t count,
                 }
         }
 
-        if (list_empty(&proc->asts)) {
-                spin_unlock(&proc->asts_spin);
-                return -EAGAIN;
-        }
-
         /* there may be both completion and blocking asts to return for
            the lkb, don't remove lkb from asts list unless no asts remain */
 
@@ -823,6 +855,7 @@ static const struct file_operations device_fops = {
 static const struct file_operations ctl_device_fops = {
         .open    = ctl_device_open,
         .release = ctl_device_close,
+        .read    = device_read,
         .write   = device_write,
         .owner   = THIS_MODULE,
 };