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Go Back   Linux Archive > Redhat > Cluster Development

 
 
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Old 12-17-2010, 11:24 AM
Steven Whitehouse
 
Default GFS2: Merge glock state fields into a bitfield

We can only merge the fields into a bitfield if the locking
rules for them are the same. In this case gl_spin covers all
of the fields (write side) but a couple of them are used
with GLF_LOCK as the read side lock, which should be ok
since we know that the field in question won't be changing
at the time.

The gl_req setting has to be done earlier (in glock.c) in order
to place it under gl_spin. The gl_reply setting also has to be
brought under gl_spin in order to comply with the new rules.

This saves 4*sizeof(unsigned int) per glock.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Cc: Bob Peterson <rpeterso@redhat.com>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 2dd1d72..08a8beb 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -567,6 +567,7 @@ __acquires(&gl->gl_spin)
set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
do_error(gl, 0); /* Fail queued try locks */
}
+ gl->gl_req = target;
spin_unlock(&gl->gl_spin);
if (glops->go_xmote_th)
glops->go_xmote_th(gl);
@@ -1353,24 +1354,28 @@ static int gfs2_should_freeze(const struct gfs2_glock *gl)
* @gl: Pointer to the glock
* @ret: The return value from the dlm
*
+ * The gl_reply field is under the gl_spin lock so that it is ok
+ * to use a bitfield shared with other glock state fields.
*/

void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
{
struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;

+ spin_lock(&gl->gl_spin);
gl->gl_reply = ret;

if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
- spin_lock(&gl->gl_spin);
if (gfs2_should_freeze(gl)) {
set_bit(GLF_FROZEN, &gl->gl_flags);
spin_unlock(&gl->gl_spin);
return;
}
- spin_unlock(&gl->gl_spin);
}
+
+ spin_unlock(&gl->gl_spin);
set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
+ smp_wmb();
gfs2_glock_hold(gl);
if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
gfs2_glock_put(gl);
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 764fbb4..8d3d2b4 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -207,12 +207,14 @@ struct gfs2_glock {

spinlock_t gl_spin;

- unsigned int gl_state;
- unsigned int gl_target;
- unsigned int gl_reply;
+ /* State fields protected by gl_spin */
+ unsigned int gl_state:2, /* Current state */
+ gl_target:2, /* Target state */
+ gl_demote_state:2, /* State requested by remote node */
+ gl_req:2, /* State in last dlm request */
+ gl_reply:8; /* Last reply from the dlm */
+
unsigned int gl_hash;
- unsigned int gl_req;
- unsigned int gl_demote_state; /* state requested by remote node */
unsigned long gl_demote_time; /* time of first demote request */
struct list_head gl_holders;

diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c
index f40ce34..6e493ae 100644
--- a/fs/gfs2/lock_dlm.c
+++ b/fs/gfs2/lock_dlm.c
@@ -153,7 +153,6 @@ static int gdlm_lock(struct gfs2_glock *gl, unsigned int req_state,
int req;
u32 lkf;

- gl->gl_req = req_state;
req = make_mode(req_state);
lkf = make_flags(gl->gl_lksb.sb_lkid, flags, req);

--
1.7.3.3
 

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