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| author | Wendy Cheng <wcheng@redhat.com> | 2007-10-05 00:27:58 -0400 |
|---|---|---|
| committer | Steven Whitehouse <swhiteho@redhat.com> | 2008-01-25 08:07:09 +0000 |
| commit | cc7e79b168a552152299bd8a8254dc099aacc993 (patch) | |
| tree | 65871c8ec495401846bc9e7030a89d3c6335f5ee | |
| parent | 49914084e797530d9baaf51df9eda77babc98fa8 (diff) | |
| download | linux-cc7e79b168a552152299bd8a8254dc099aacc993.tar.gz linux-cc7e79b168a552152299bd8a8254dc099aacc993.tar.bz2 linux-cc7e79b168a552152299bd8a8254dc099aacc993.zip | |
[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>
| -rw-r--r-- | fs/gfs2/glock.c | 15 | ||||
| -rw-r--r-- | fs/gfs2/incore.h | 2 |
2 files changed, 16 insertions, 1 deletions
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index a37efe4aae6f..104e83ff874f 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); } diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h index eaddfb5a8e6f..662182bfbff7 100644 --- a/fs/gfs2/incore.h +++ b/fs/gfs2/incore.h @@ -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; |