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authorWendy Cheng <wcheng@redhat.com>2007-10-05 00:27:58 -0400
committerSteven Whitehouse <swhiteho@redhat.com>2008-01-25 08:07:09 +0000
commitcc7e79b168a552152299bd8a8254dc099aacc993 (patch)
tree65871c8ec495401846bc9e7030a89d3c6335f5ee /fs/gfs2/glock.c
parent49914084e797530d9baaf51df9eda77babc98fa8 (diff)
downloadconfigs-cc7e79b168a552152299bd8a8254dc099aacc993.tar.gz
[GFS2] Handle multiple glock demote requests
Fix a race condition where multiple glock demote requests are sent to a node back-to-back. This patch does a check inside handle_callback() to see whether a demote request is in progress. If true, it sets a flag to make sure run_queue() will loop again to handle the new request, instead of erronously setting gl_demote_state to a different state. Signed-off-by: S. Wendy Cheng <wcheng@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/gfs2/glock.c')
-rw-r--r--fs/gfs2/glock.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index a37efe4aae6..104e83ff874 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -567,7 +567,10 @@ static int rq_demote(struct gfs2_glock *gl)
gfs2_demote_wake(gl);
return 0;
}
+
set_bit(GLF_LOCK, &gl->gl_flags);
+ set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
+
if (gl->gl_demote_state == LM_ST_UNLOCKED ||
gl->gl_state != LM_ST_EXCLUSIVE) {
spin_unlock(&gl->gl_spin);
@@ -576,7 +579,9 @@ static int rq_demote(struct gfs2_glock *gl)
spin_unlock(&gl->gl_spin);
gfs2_glock_xmote_th(gl, NULL);
}
+
spin_lock(&gl->gl_spin);
+ clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
return 0;
}
@@ -606,6 +611,11 @@ static void run_queue(struct gfs2_glock *gl)
} else if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
blocked = rq_demote(gl);
+ if (gl->gl_waiters2 && !blocked) {
+ set_bit(GLF_DEMOTE, &gl->gl_flags);
+ gl->gl_demote_state = LM_ST_UNLOCKED;
+ }
+ gl->gl_waiters2 = 0;
} else if (!list_empty(&gl->gl_waiters3)) {
gh = list_entry(gl->gl_waiters3.next,
struct gfs2_holder, gh_list);
@@ -722,7 +732,10 @@ static void handle_callback(struct gfs2_glock *gl, unsigned int state,
}
} else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != state) {
- gl->gl_demote_state = LM_ST_UNLOCKED;
+ if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
+ gl->gl_waiters2 = 1;
+ else
+ gl->gl_demote_state = LM_ST_UNLOCKED;
}
spin_unlock(&gl->gl_spin);
}