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Commit 02ffad08 authored by Benjamin Marzinski's avatar Benjamin Marzinski Committed by Steven Whitehouse
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GFS2: Fix locking bug in failed shared to exclusive conversion 



After calling out to the dlm, GFS2 sets the new state of a glock to
gl_target in gdlm_ast().  However, gl_target is not always the lock
state that was requested. If a conversion from shared to exclusive
fails, finish_xmote() will call do_xmote() with LM_ST_UNLOCKED, instead
of gl->gl_target, so that it can reacquire the lock in exlusive the next
time around.  In this case, setting the lock to gl_target in gdlm_ast()
will make GFS2 think that it has the glock in exclusive mode, when
really, it doesn't have the glock locked at all.  This patch adds a new
field to the gfs2_glock structure, gl_req, to track the mode that was
requested.

Signed-off-by: default avatarBenjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 229615de

fs/gfs2/incore.h

+1 −0
Original line number Diff line number Diff line
@@ -203,6 +203,7 @@ struct gfs2_glock { 
	unsigned int gl_target;

	unsigned int gl_reply;

	unsigned int gl_hash;

	unsigned int gl_req;

	unsigned int gl_demote_state; /* state requested by remote node */

	unsigned long gl_demote_time; /* time of first demote request */

	struct list_head gl_holders;

fs/gfs2/lock_dlm.c

+4 −3
Original line number Diff line number Diff line
@@ -46,11 +46,11 @@ static void gdlm_ast(void *arg) 
		BUG();

	}



	ret = gl->gl_target;

	ret = gl->gl_req;

	if (gl->gl_lksb.sb_flags & DLM_SBF_ALTMODE) {

		if (gl->gl_target == LM_ST_SHARED)

		if (gl->gl_req == LM_ST_SHARED)

			ret = LM_ST_DEFERRED;

		else if (gl->gl_target == LM_ST_DEFERRED)

		else if (gl->gl_req == LM_ST_DEFERRED)

			ret = LM_ST_SHARED;

		else

			BUG();
@@ -147,6 +147,7 @@ static unsigned int gdlm_lock(struct gfs2_glock *gl, 
	int req;

	u32 lkf;



	gl->gl_req = req_state;

	req = make_mode(req_state);

	lkf = make_flags(gl->gl_lksb.sb_lkid, flags, req);