lockd: handle test_lock deferrals
Marc Eshel [Tue, 28 Nov 2006 21:27:06 +0000 (16:27 -0500)]
Rewrite nlmsvc_testlock() to use the new asynchronous interface: instead of
immediately doing a posix_test_lock(), we first look for a matching block.
If the subsequent test_lock returns anything other than -EINPROGRESS, we
then remove the block we've found and return the results.

If it returns -EINPROGRESS, then we defer the lock request.

In the case where the block we find in the first step has B_QUEUED set,
we bypass the vfs_test_lock entirely, instead using the block to decide how
to respond:
with nlm_lck_denied if B_TIMED_OUT is set.
with nlm_granted if B_GOT_CALLBACK is set.
by dropping if neither B_TIMED_OUT nor B_GOT_CALLBACK is set

Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/lockd/svc4proc.c
fs/lockd/svclock.c
fs/lockd/svcproc.c

index a1bccad..205d8be 100644 (file)
@@ -100,6 +100,8 @@ nlm4svc_proc_test(struct svc_rqst *rqstp, struct nlm_args *argp,
 
        /* Now check for conflicting locks */
        resp->status = nlmsvc_testlock(rqstp, file, &argp->lock, &resp->lock, &resp->cookie);
+       if (resp->status == nlm_drop_reply)
+               return rpc_drop_reply;
 
        dprintk("lockd: TEST4          status %d\n", ntohl(resp->status));
        nlm_release_host(host);
index 7ab2e60..b7a8174 100644 (file)
@@ -173,7 +173,7 @@ found:
  */
 static inline struct nlm_block *
 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
-                               struct nlm_lock *lock, struct nlm_cookie *cookie)
+               struct nlm_lock *lock, struct nlm_cookie *cookie)
 {
        struct nlm_block        *block;
        struct nlm_host         *host;
@@ -210,6 +210,7 @@ nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
        block->b_daemon = rqstp->rq_server;
        block->b_host   = host;
        block->b_file   = file;
+       block->b_fl = NULL;
        file->f_count++;
 
        /* Add to file's list of blocks */
@@ -446,6 +447,10 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
                struct nlm_lock *lock, struct nlm_lock *conflock,
                struct nlm_cookie *cookie)
 {
+       struct nlm_block        *block = NULL;
+       int                     error;
+       __be32                  ret;
+
        dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
                                file->f_file->f_path.dentry->d_inode->i_sb->s_id,
                                file->f_file->f_path.dentry->d_inode->i_ino,
@@ -453,22 +458,70 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
                                (long long)lock->fl.fl_start,
                                (long long)lock->fl.fl_end);
 
-       if (posix_test_lock(file->f_file, &lock->fl)) {
-               dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
-                               lock->fl.fl_type,
-                               (long long)lock->fl.fl_start,
-                               (long long)lock->fl.fl_end);
-               conflock->caller = "somehost";  /* FIXME */
-               conflock->len = strlen(conflock->caller);
-               conflock->oh.len = 0;           /* don't return OH info */
-               conflock->svid = lock->fl.fl_pid;
-               conflock->fl.fl_type = lock->fl.fl_type;
-               conflock->fl.fl_start = lock->fl.fl_start;
-               conflock->fl.fl_end = lock->fl.fl_end;
-               return nlm_lck_denied;
+       /* Get existing block (in case client is busy-waiting) */
+       block = nlmsvc_lookup_block(file, lock);
+
+       if (block == NULL) {
+               struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
+
+               if (conf == NULL)
+                       return nlm_granted;
+               block = nlmsvc_create_block(rqstp, file, lock, cookie);
+               if (block == NULL) {
+                       kfree(conf);
+                       return nlm_granted;
+               }
+               block->b_fl = conf;
+       }
+       if (block->b_flags & B_QUEUED) {
+               dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
+                       block, block->b_flags, block->b_fl);
+               if (block->b_flags & B_TIMED_OUT) {
+                       nlmsvc_unlink_block(block);
+                       return nlm_lck_denied;
+               }
+               if (block->b_flags & B_GOT_CALLBACK) {
+                       if (block->b_fl != NULL
+                                       && block->b_fl->fl_type != F_UNLCK) {
+                               lock->fl = *block->b_fl;
+                               goto conf_lock;
+                       }
+                       else {
+                               nlmsvc_unlink_block(block);
+                               return nlm_granted;
+                       }
+               }
+               return nlm_drop_reply;
+       }
+
+       error = vfs_test_lock(file->f_file, &lock->fl);
+       if (error == -EINPROGRESS)
+               return nlmsvc_defer_lock_rqst(rqstp, block);
+       if (error) {
+               ret = nlm_lck_denied_nolocks;
+               goto out;
+       }
+       if (lock->fl.fl_type == F_UNLCK) {
+               ret = nlm_granted;
+               goto out;
        }
 
-       return nlm_granted;
+conf_lock:
+       dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
+               lock->fl.fl_type, (long long)lock->fl.fl_start,
+               (long long)lock->fl.fl_end);
+       conflock->caller = "somehost";  /* FIXME */
+       conflock->len = strlen(conflock->caller);
+       conflock->oh.len = 0;           /* don't return OH info */
+       conflock->svid = lock->fl.fl_pid;
+       conflock->fl.fl_type = lock->fl.fl_type;
+       conflock->fl.fl_start = lock->fl.fl_start;
+       conflock->fl.fl_end = lock->fl.fl_end;
+       ret = nlm_lck_denied;
+out:
+       if (block)
+               nlmsvc_release_block(block);
+       return ret;
 }
 
 /*
@@ -549,7 +602,6 @@ nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
        else
                block->b_flags |= B_TIMED_OUT;
        if (conf) {
-               block->b_fl = kzalloc(sizeof(struct file_lock), GFP_KERNEL);
                if (block->b_fl)
                        locks_copy_lock(block->b_fl, conf);
        }
index d13b827..40b5cf4 100644 (file)
@@ -33,6 +33,7 @@ cast_to_nlm(__be32 status, u32 vers)
                case nlm_lck_denied_nolocks:
                case nlm_lck_blocked:
                case nlm_lck_denied_grace_period:
+               case nlm_drop_reply:
                        break;
                case nlm4_deadlock:
                        status = nlm_lck_denied;
@@ -128,6 +129,8 @@ nlmsvc_proc_test(struct svc_rqst *rqstp, struct nlm_args *argp,
 
        /* Now check for conflicting locks */
        resp->status = cast_status(nlmsvc_testlock(rqstp, file, &argp->lock, &resp->lock, &resp->cookie));
+       if (resp->status == nlm_drop_reply)
+               return rpc_drop_reply;
 
        dprintk("lockd: TEST          status %d vers %d\n",
                ntohl(resp->status), rqstp->rq_vers);