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GFS2: Fix recovery stuck bug (try #2)

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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 <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse 2010-08-02 10:15:17 +01:00
parent c639d5d8f6
commit 0809f6ec18
1 changed files with 39 additions and 7 deletions
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46
fs/gfs2/glock.c
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@ -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);