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: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 980a0864ca6ce39df5968114b01d21e089dcc10d..399d1b97804972b3b6f4f27c801f6f2b823dbd0b 100644 (file)
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -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;

diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c
index a0bb7d2251a00f453c05ad16ae9332d4c3997cac..46df988323bc035285d5663429588038df6d6b9c 100644 (file)
--- a/fs/gfs2/lock_dlm.c
+++ b/fs/gfs2/lock_dlm.c
@@ -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);