[Devel] Re: [PATCH 6/12] gfs2: make gfs2_glock.gl_owner_pid be a struct pid *

[Pavel Emelyanov]

Steven Whitehouse wrote:
> Hi,
> 
> Would you like me to take these two GFS2 patches into my git tree for
> the next merge window, or are you intending that these should go to
> Linus in this merge window? Either way I'm happy to add my:

Actually, I hope that all these patches are merged in this merge
window, but if Andrew decides, that these two are not for -mm 
tree, then I will be also happy if they stay at your tree up to 
the 2.6.26 merge window.

> Signed-off-by: Steven Whitehouse <swhiteho at redhat.com>

Thanks! :)

> Steve.
> 
> On Tue, 2008-01-29 at 16:55 +0300, Pavel Emelyanov wrote:
>> The gl_owner_pid field is used to get the lock owning
>> task by its pid, so make it in a proper manner, i.e.
>> by using the struct pid pointer and pid_task() function.
>>
>> The pid_task() becomes exported for the gfs2 module.
>>
>> Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
>>
>> ---
>>  fs/gfs2/glock.c  |   19 ++++++++++++-------
>>  fs/gfs2/incore.h |    2 +-
>>  2 files changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
>> index 80e09c5..5fe585f 100644
>> --- a/fs/gfs2/glock.c
>> +++ b/fs/gfs2/glock.c
>> @@ -334,7 +334,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
>>  	gl->gl_state = LM_ST_UNLOCKED;
>>  	gl->gl_demote_state = LM_ST_EXCLUSIVE;
>>  	gl->gl_hash = hash;
>> -	gl->gl_owner_pid = 0;
>> +	gl->gl_owner_pid = NULL;
>>  	gl->gl_ip = 0;
>>  	gl->gl_ops = glops;
>>  	gl->gl_req_gh = NULL;
>> @@ -631,7 +631,7 @@ static void gfs2_glmutex_lock(struct gfs2_glock *gl)
>>  		wait_on_holder(&gh);
>>  		gfs2_holder_uninit(&gh);
>>  	} else {
>> -		gl->gl_owner_pid = current->pid;
>> +		gl->gl_owner_pid = get_pid(task_pid(current));
>>  		gl->gl_ip = (unsigned long)__builtin_return_address(0);
>>  		spin_unlock(&gl->gl_spin);
>>  	}
>> @@ -652,7 +652,7 @@ static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
>>  	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
>>  		acquired = 0;
>>  	} else {
>> -		gl->gl_owner_pid = current->pid;
>> +		gl->gl_owner_pid = get_pid(task_pid(current));
>>  		gl->gl_ip = (unsigned long)__builtin_return_address(0);
>>  	}
>>  	spin_unlock(&gl->gl_spin);
>> @@ -668,12 +668,17 @@ static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
>>  
>>  static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
>>  {
>> +	struct pid *pid;
>> +
>>  	spin_lock(&gl->gl_spin);
>>  	clear_bit(GLF_LOCK, &gl->gl_flags);
>> -	gl->gl_owner_pid = 0;
>> +	pid = gl->gl_owner_pid;
>> +	gl->gl_owner_pid = NULL;
>>  	gl->gl_ip = 0;
>>  	run_queue(gl);
>>  	spin_unlock(&gl->gl_spin);
>> +
>> +	put_pid(pid);
>>  }
>>  
>>  /**
>> @@ -1877,13 +1882,13 @@ static int dump_glock(struct glock_iter *gi, struct gfs2_glock *gl)
>>  	print_dbg(gi, "  gl_ref = %d\n", atomic_read(&gl->gl_ref));
>>  	print_dbg(gi, "  gl_state = %u\n", gl->gl_state);
>>  	if (gl->gl_owner_pid) {
>> -		gl_owner = find_task_by_pid(gl->gl_owner_pid);
>> +		gl_owner = pid_task(gl->gl_owner_pid, PIDTYPE_PID);
>>  		if (gl_owner)
>>  			print_dbg(gi, "  gl_owner = pid %d (%s)\n",
>> -				  gl->gl_owner_pid, gl_owner->comm);
>> +				  pid_nr(gl->gl_owner_pid), gl_owner->comm);
>>  		else
>>  			print_dbg(gi, "  gl_owner = %d (ended)\n",
>> -				  gl->gl_owner_pid);
>> +				  pid_nr(gl->gl_owner_pid));
>>  	} else
>>  		print_dbg(gi, "  gl_owner = -1\n");
>>  	print_dbg(gi, "  gl_ip = %lu\n", gl->gl_ip);
>> diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
>> index 1339996..8ad1c3f 100644
>> --- a/fs/gfs2/incore.h
>> +++ b/fs/gfs2/incore.h
>> @@ -182,7 +182,7 @@ struct gfs2_glock {
>>  	unsigned int gl_hash;
>>  	unsigned int gl_demote_state; /* state requested by remote node */
>>  	unsigned long gl_demote_time; /* time of first demote request */
>> -	pid_t gl_owner_pid;
>> +	struct pid *gl_owner_pid;
>>  	unsigned long gl_ip;
>>  	struct list_head gl_holders;
>>  	struct list_head gl_waiters1;	/* HIF_MUTEX */
>> diff --git a/kernel/pid.c b/kernel/pid.c
>> index e4e5fc8..4776915 100644
>> --- a/kernel/pid.c
>> +++ b/kernel/pid.c
>> @@ -367,6 +367,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
>>  	}
>>  	return result;
>>  }
>> +EXPORT_SYMBOL(pid_task);
>>  
>>  /*
>>   * Must be called under rcu_read_lock() or with tasklist_lock read-held.
> 
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