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[PATCH] NLM: fix a client-side race on blocking locks.

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If the lock blocks, the server may send us a GRANTED message that
 races with the reply to our LOCK request. Make sure that we catch
 the GRANTED by queueing up our request on the nlm_blocked list
 before we send off the first LOCK rpc call.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust
2005-06-22 17:16:31 +00:00
parent 4f15e2b1f4
commit ecdbf769b2
3 changed files with 96 additions and 50 deletions
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40
fs/lockd/clntproc.c
View File

@@ -21,6 +21,7 @@
#define NLMDBG_FACILITY NLMDBG_CLIENT
#define NLMCLNT_GRACE_WAIT (5*HZ)
#define NLMCLNT_POLL_TIMEOUT (30*HZ)
static int nlmclnt_test(struct nlm_rqst *, struct file_lock *);
static int nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
@@ -553,7 +554,8 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
{
struct nlm_host *host = req->a_host;
struct nlm_res *resp = &req->a_res;
int status;
long timeout;
int status;
if (!host->h_monitored && nsm_monitor(host) < 0) {
printk(KERN_NOTICE "lockd: failed to monitor %s\n",
@@ -562,15 +564,32 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
goto out;
}
do {
if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0) {
if (resp->status != NLM_LCK_BLOCKED)
break;
status = nlmclnt_block(host, fl, &resp->status);
}
if (req->a_args.block) {
status = nlmclnt_prepare_block(req, host, fl);
if (status < 0)
goto out;
} while (resp->status == NLM_LCK_BLOCKED && req->a_args.block);
}
for(;;) {
status = nlmclnt_call(req, NLMPROC_LOCK);
if (status < 0)
goto out_unblock;
if (resp->status != NLM_LCK_BLOCKED)
break;
/* Wait on an NLM blocking lock */
timeout = nlmclnt_block(req, NLMCLNT_POLL_TIMEOUT);
/* Did a reclaimer thread notify us of a server reboot? */
if (resp->status == NLM_LCK_DENIED_GRACE_PERIOD)
continue;
if (resp->status != NLM_LCK_BLOCKED)
break;
if (timeout >= 0)
continue;
/* We were interrupted. Send a CANCEL request to the server
* and exit
*/
status = (int)timeout;
goto out_unblock;
}
if (resp->status == NLM_LCK_GRANTED) {
fl->fl_u.nfs_fl.state = host->h_state;
@@ -579,6 +598,11 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
do_vfs_lock(fl);
}
status = nlm_stat_to_errno(resp->status);
out_unblock:
nlmclnt_finish_block(req);
/* Cancel the blocked request if it is still pending */
if (resp->status == NLM_LCK_BLOCKED)
nlmclnt_cancel(host, fl);
out:
nlmclnt_release_lockargs(req);
return status;