This patch adds two new states to the glock state machine. The
first is a normal call for gl_target. The second is an abnormal
call for cases in which dlm was unable to grant our request.
Signed-off-by: Bob Peterson <rpete...@redhat.com>
---
fs/gfs2/glock.c | 37 ++++++++++++++++++++++++++++---------
fs/gfs2/glock.h | 3 +++
2 files changed, 31 insertions(+), 9 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 5e0eac782c32..b541c4053dd7 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -60,7 +60,7 @@ struct gfs2_glock_iter {
typedef void (*glock_examiner) (struct gfs2_glock * gl);
-static void do_xmote(struct gfs2_glock *gl, unsigned int target);
+static void __state_machine(struct gfs2_glock *gl, int new_state);
static void state_machine(struct gfs2_glock *gl, int new_state);
static struct dentry *gfs2_root;
@@ -444,9 +444,12 @@ static void gfs2_demote_wake(struct gfs2_glock *gl)
* finish_xmote - The DLM has replied to one of our lock requests
* @gl: The glock
*
+ * Returns: -EAGAIN if do_xmote should be called next
+ * -EBUSY if dlm could not satisfy the request
+ * else 0
*/
-static void finish_xmote(struct gfs2_glock *gl)
+static int finish_xmote(struct gfs2_glock *gl)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
struct gfs2_holder *gh;
@@ -484,19 +487,17 @@ static void finish_xmote(struct gfs2_glock *gl)
switch(state) {
/* Unlocked due to conversion deadlock, try again */
case LM_ST_UNLOCKED:
- do_xmote(gl, gl->gl_target);
- break;
+ return -EAGAIN;
/* Conversion fails, unlock and try again */
case LM_ST_SHARED:
case LM_ST_DEFERRED:
- do_xmote(gl, LM_ST_UNLOCKED);
- break;
+ return -EBUSY;
default: /* Everything else */
fs_err(gl->gl_name.ln_sbd, "wanted %u got %u\n",
gl->gl_target, state);
GLOCK_BUG_ON(gl, 1);
}
- return;
+ return 0;
}
/* Fast path - we got what we asked for */
@@ -514,10 +515,11 @@ static void finish_xmote(struct gfs2_glock *gl)
}
rv = do_promote(gl);
if (rv == 2)
- return;
+ return 0;
}
out:
clear_bit(GLF_LOCK, &gl->gl_flags);
+ return 0;
}
/**
@@ -656,7 +658,7 @@ __acquires(&gl->gl_lockref.lock)
if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
do_error(gl, 0); /* Fail queued try locks */
}
- do_xmote(gl, gl->gl_target);
+ __state_machine(gl, GL_ST_DO_XMOTE);
return;
}
@@ -674,6 +676,8 @@ __acquires(&gl->gl_lockref.lock)
*/
static void __state_machine(struct gfs2_glock *gl, int new_state)
{
+ int ret;
+
BUG_ON(!spin_is_locked(&gl->gl_lockref.lock));
do {
@@ -685,6 +689,21 @@ static void __state_machine(struct gfs2_glock *gl, int
new_state)
case GL_ST_FINISH_XMOTE:
gl->gl_mch = GL_ST_IDLE;
+ ret = finish_xmote(gl);
+ if (ret == -EBUSY)
+ gl->gl_mch = GL_ST_DO_XMOTE_UNLOCK;
+ else if (ret == -EAGAIN)
+ gl->gl_mch = GL_ST_DO_XMOTE;
+ break;
+
+ case GL_ST_DO_XMOTE:
+ gl->gl_mch = GL_ST_IDLE;
+ do_xmote(gl, gl->gl_target);
+ break;
+
+ case GL_ST_DO_XMOTE_UNLOCK:
+ gl->gl_mch = GL_ST_IDLE;
+ do_xmote(gl, LM_ST_UNLOCKED);
finish_xmote(gl);
break;
}
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index 88043d610d64..8333bbc5a197 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -123,6 +123,9 @@ enum {
enum gl_machine_states {
GL_ST_IDLE = 0, /* State machine idle; no transition needed */
GL_ST_FINISH_XMOTE = 1, /* Promotion/demotion complete */
+ GL_ST_DO_XMOTE = 2, /* Promote or demote a waiter */
+ GL_ST_DO_XMOTE_UNLOCK = 3, /* Promote or demote a waiter after a failed
+ state change attempt from dlm. */
};
struct lm_lockops {
--
2.19.1
