Red Hat bugzilla 295641... Wendy
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 erroneously setting gl_demote_state to a different state.
Signed-off-by: S. Wendy Cheng <[EMAIL PROTECTED]>
glock.c | 13 ++++++++++++-
incore.h | 2 ++
2 files changed, 14 insertions(+), 1 deletion(-)
--- e48-brew/fs/gfs2/incore.h 2007-09-20 17:29:00.000000000 -0500
+++ e48/fs/gfs2/incore.h 2007-10-02 16:45:38.000000000 -0500
@@ -171,6 +171,7 @@ enum {
GLF_DEMOTE = 3,
GLF_PENDING_DEMOTE = 4,
GLF_DIRTY = 5,
+ GLF_DEMOTE_IN_PROGRESS = 6,
};
struct gfs2_glock {
@@ -190,6 +191,7 @@ struct gfs2_glock {
struct list_head gl_holders;
struct list_head gl_waiters1; /* HIF_MUTEX */
struct list_head gl_waiters3; /* HIF_PROMOTE */
+ int gl_waiters2; /* GIF_DEMOTE */
const struct gfs2_glock_operations *gl_ops;
--- e48-brew/fs/gfs2/glock.c 2007-09-18 11:26:53.000000000 -0500
+++ e48/fs/gfs2/glock.c 2007-10-02 18:19:12.000000000 -0500
@@ -567,6 +567,7 @@ static int rq_demote(struct gfs2_glock *
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);
@@ -575,6 +576,8 @@ static int rq_demote(struct gfs2_glock *
spin_unlock(&gl->gl_spin);
gfs2_glock_xmote_th(gl, NULL);
}
+
+ clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
spin_lock(&gl->gl_spin);
return 0;
@@ -605,6 +608,11 @@ static void run_queue(struct gfs2_glock
} 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);
@@ -721,7 +729,10 @@ static void handle_callback(struct gfs2_
}
} 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);
}
