From 0809f6ec18bbce54c996f5c36f4b9d371075c98b Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Mon, 2 Aug 2010 10:15:17 +0100 Subject: [PATCH] GFS2: Fix recovery stuck bug (try #2) This is a clean up of the code which deals with LM_FLAG_NOEXP which aims to remove any possible race conditions by using gl_spin to cover the gap between testing for the LM_FLAG_NOEXP and the GL_FROZEN flag. Signed-off-by: Steven Whitehouse --- fs/gfs2/glock.c | 46 +++++++++++++++++++++++++++++++++++++++------- 1 file changed, 39 insertions(+), 7 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 2b3d8f8a8393..9adf8f924e08 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1063,6 +1063,9 @@ int gfs2_glock_nq(struct gfs2_holder *gh) spin_lock(&gl->gl_spin); add_to_queue(gh); + if ((LM_FLAG_NOEXP & gh->gh_flags) && + test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) + set_bit(GLF_REPLY_PENDING, &gl->gl_flags); run_queue(gl, 1); spin_unlock(&gl->gl_spin); @@ -1319,6 +1322,36 @@ void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state) gfs2_glock_put(gl); } +/** + * gfs2_should_freeze - Figure out if glock should be frozen + * @gl: The glock in question + * + * Glocks are not frozen if (a) the result of the dlm operation is + * an error, (b) the locking operation was an unlock operation or + * (c) if there is a "noexp" flagged request anywhere in the queue + * + * Returns: 1 if freezing should occur, 0 otherwise + */ + +static int gfs2_should_freeze(const struct gfs2_glock *gl) +{ + const struct gfs2_holder *gh; + + if (gl->gl_reply & ~LM_OUT_ST_MASK) + return 0; + if (gl->gl_target == LM_ST_UNLOCKED) + return 0; + + list_for_each_entry(gh, &gl->gl_holders, gh_list) { + if (test_bit(HIF_HOLDER, &gh->gh_iflags)) + continue; + if (LM_FLAG_NOEXP & gh->gh_flags) + return 0; + } + + return 1; +} + /** * gfs2_glock_complete - Callback used by locking * @gl: Pointer to the glock @@ -1329,18 +1362,17 @@ void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state) void gfs2_glock_complete(struct gfs2_glock *gl, int ret) { struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct; + gl->gl_reply = ret; + if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) { - struct gfs2_holder *gh; spin_lock(&gl->gl_spin); - gh = find_first_waiter(gl); - if ((!(gh && (gh->gh_flags & LM_FLAG_NOEXP)) && - (gl->gl_target != LM_ST_UNLOCKED)) || - ((ret & ~LM_OUT_ST_MASK) != 0)) + if (gfs2_should_freeze(gl)) { set_bit(GLF_FROZEN, &gl->gl_flags); - spin_unlock(&gl->gl_spin); - if (test_bit(GLF_FROZEN, &gl->gl_flags)) + spin_unlock(&gl->gl_spin); return; + } + spin_unlock(&gl->gl_spin); } set_bit(GLF_REPLY_PENDING, &gl->gl_flags); gfs2_glock_hold(gl);