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authorBob Peterson <rpeterso@redhat.com>2007-12-11 19:13:54 -0600
committerSteven Whitehouse <swhiteho@redhat.com>2008-01-25 08:13:52 +0000
commit398bbe68321947f6763fbc259a01eb548ce19408 (patch)
tree64cf07eb0f461aa5d26c2abdc873c8727d8a2bad /fs/gfs2
parent5fdc2eeb5d1d3800367f471690b01fcd1fd5b963 (diff)
[GFS2] Reorganize function gfs2_glmutex_lock
This patch optimizes the function gfs2_glmutex_lock. The basic theory is: Why bother initializing a holder, setting up wait bits and then waiting on them, if you know the glock can be yours. So the holder stuff is placed inside the if checking if the glock is locked. This one needs careful scrutiny because changing anything to do with locking should strike terror into one's heart. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2')
-rw-r--r--fs/gfs2/glock.c23
1 files changed, 9 insertions, 14 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index a7f3c462d4f..80e09c50590 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1,6 +1,6 @@
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
- * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
@@ -620,26 +620,21 @@ static void run_queue(struct gfs2_glock *gl)
static void gfs2_glmutex_lock(struct gfs2_glock *gl)
{
- struct gfs2_holder gh;
-
- gfs2_holder_init(gl, 0, 0, &gh);
- if (test_and_set_bit(HIF_WAIT, &gh.gh_iflags))
- BUG();
-
spin_lock(&gl->gl_spin);
if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
+ struct gfs2_holder gh;
+
+ gfs2_holder_init(gl, 0, 0, &gh);
+ set_bit(HIF_WAIT, &gh.gh_iflags);
list_add_tail(&gh.gh_list, &gl->gl_waiters1);
+ spin_unlock(&gl->gl_spin);
+ wait_on_holder(&gh);
+ gfs2_holder_uninit(&gh);
} else {
gl->gl_owner_pid = current->pid;
gl->gl_ip = (unsigned long)__builtin_return_address(0);
- clear_bit(HIF_WAIT, &gh.gh_iflags);
- smp_mb();
- wake_up_bit(&gh.gh_iflags, HIF_WAIT);
+ spin_unlock(&gl->gl_spin);
}
- spin_unlock(&gl->gl_spin);
-
- wait_on_holder(&gh);
- gfs2_holder_uninit(&gh);
}
/**