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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: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Benjamin Marzinski 2009-03-06 10:03:20 -06:00 committed by Steven Whitehouse
parent 229615def3
commit 02ffad08e8
2 changed files with 5 additions and 3 deletions
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1
fs/gfs2/incore.h
View File

@ -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;

7
fs/gfs2/lock_dlm.c
View File

@ -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);