Commit cc7e79b1 authored by Wendy Cheng's avatar Wendy Cheng Committed by Steven Whitehouse

[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: default avatarS. Wendy Cheng <wcheng@redhat.com>
Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 49914084
...@@ -567,7 +567,10 @@ static int rq_demote(struct gfs2_glock *gl) ...@@ -567,7 +567,10 @@ static int rq_demote(struct gfs2_glock *gl)
gfs2_demote_wake(gl); gfs2_demote_wake(gl);
return 0; return 0;
} }
set_bit(GLF_LOCK, &gl->gl_flags); set_bit(GLF_LOCK, &gl->gl_flags);
set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
if (gl->gl_demote_state == LM_ST_UNLOCKED || if (gl->gl_demote_state == LM_ST_UNLOCKED ||
gl->gl_state != LM_ST_EXCLUSIVE) { gl->gl_state != LM_ST_EXCLUSIVE) {
spin_unlock(&gl->gl_spin); spin_unlock(&gl->gl_spin);
...@@ -576,7 +579,9 @@ static int rq_demote(struct gfs2_glock *gl) ...@@ -576,7 +579,9 @@ static int rq_demote(struct gfs2_glock *gl)
spin_unlock(&gl->gl_spin); spin_unlock(&gl->gl_spin);
gfs2_glock_xmote_th(gl, NULL); gfs2_glock_xmote_th(gl, NULL);
} }
spin_lock(&gl->gl_spin); spin_lock(&gl->gl_spin);
clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
return 0; return 0;
} }
...@@ -606,6 +611,11 @@ static void run_queue(struct gfs2_glock *gl) ...@@ -606,6 +611,11 @@ static void run_queue(struct gfs2_glock *gl)
} else if (test_bit(GLF_DEMOTE, &gl->gl_flags)) { } else if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
blocked = rq_demote(gl); 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)) { } else if (!list_empty(&gl->gl_waiters3)) {
gh = list_entry(gl->gl_waiters3.next, gh = list_entry(gl->gl_waiters3.next,
struct gfs2_holder, gh_list); struct gfs2_holder, gh_list);
...@@ -722,7 +732,10 @@ static void handle_callback(struct gfs2_glock *gl, unsigned int state, ...@@ -722,7 +732,10 @@ static void handle_callback(struct gfs2_glock *gl, unsigned int state,
} }
} else if (gl->gl_demote_state != LM_ST_UNLOCKED && } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
gl->gl_demote_state != state) { 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); spin_unlock(&gl->gl_spin);
} }
......
...@@ -171,6 +171,7 @@ enum { ...@@ -171,6 +171,7 @@ enum {
GLF_DEMOTE = 3, GLF_DEMOTE = 3,
GLF_PENDING_DEMOTE = 4, GLF_PENDING_DEMOTE = 4,
GLF_DIRTY = 5, GLF_DIRTY = 5,
GLF_DEMOTE_IN_PROGRESS = 6,
}; };
struct gfs2_glock { struct gfs2_glock {
...@@ -190,6 +191,7 @@ struct gfs2_glock { ...@@ -190,6 +191,7 @@ struct gfs2_glock {
struct list_head gl_holders; struct list_head gl_holders;
struct list_head gl_waiters1; /* HIF_MUTEX */ struct list_head gl_waiters1; /* HIF_MUTEX */
struct list_head gl_waiters3; /* HIF_PROMOTE */ struct list_head gl_waiters3; /* HIF_PROMOTE */
int gl_waiters2; /* GIF_DEMOTE */
const struct gfs2_glock_operations *gl_ops; const struct gfs2_glock_operations *gl_ops;
......
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