On Sat, 2007-02-03 at 00:34 -0500, J. Bruce Fields wrote:
> From: Marc Eshel <eshel@xxxxxxxxxxxxxxx> - unquoted
>
> Add code to handle file system callback when the lock is finally granted.
>
> Signed-off-by: Marc Eshel <eshel@xxxxxxxxxxxxxxx>
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
> ---
> fs/lockd/svclock.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 files changed, 72 insertions(+), 6 deletions(-)
>
> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index 00e657a..a558360 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -261,6 +261,8 @@ static void nlmsvc_free_block(struct kref *kref)
> nlmsvc_freegrantargs(block->b_call);
> nlm_release_call(block->b_call);
> nlm_release_file(block->b_file);
> + if (block->b_fl)
> + kfree(block->b_fl);
> kfree(block);
> }
>
> @@ -525,6 +527,32 @@ nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
> }
>
> /*
> + * This is a callback from the filesystem for VFS file lock requests.
> + * It will be used if fl_notify is defined and the filesystem can not
> + * respond to the request immediately.
> + * For GETLK request it will copy the reply to the nlm_block.
> + * For SETLK or SETLKW request it will get the local posix lock.
> + * In all cases it will move the block to the head of nlm_blocked q where
> + * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
> + * deferred rpc for GETLK and SETLK.
> + */
> +static void
> +nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
> + int result)
> +{
> + block->b_flags |= B_GOT_CALLBACK;
> + if (result == 0)
> + block->b_granted = 1;
> + else
> + block->b_flags |= B_TOO_LATE;
> + if (conf) {
> + block->b_fl = kzalloc(sizeof(struct file_lock), GFP_KERNEL);
> + if (block->b_fl)
> + locks_copy_lock(block->b_fl, conf);
> + }
> +}
> +
> +/*
> * Unblock a blocked lock request. This is a callback invoked from the
> * VFS layer when a lock on which we blocked is removed.
> *
> @@ -535,18 +563,33 @@ static int
> nlmsvc_notify_blocked(struct file_lock *fl, struct file_lock *conf, int result)
> {
> struct nlm_block *block;
> + int rc = -ENOENT;
>
> dprintk("lockd: nlmsvc_notify_blocked lock %p conf %p result %d\n",
> fl, conf, result);
> + lock_kernel();
> list_for_each_entry(block, &nlm_blocked, b_list) {
> if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
> + dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
> + block, block->b_flags);
> + if (block->b_flags & B_QUEUED) {
> + if (block->b_flags & B_TOO_LATE) {
> + rc = -ENOLCK;
> + break;
> + }
> + nlmsvc_update_deferred_block(block, conf, result);
but nlmsvc_update_deferred_block() can sleep! How are you protecting
against races with notification? Also, how are you guaranteeing that the
block queue won't change underneath you when you lose the BKL.
> + }
> nlmsvc_insert_block(block, 0);
> svc_wake_up(block->b_daemon);
> - return;
> + rc = 0;
> + break;
> }
> }
> + unlock_kernel();
>
> - printk(KERN_WARNING "lockd: notification for unknown block!\n");
> + if (rc == -ENOENT)
> + printk(KERN_WARNING "lockd: notification for unknown block!\n");
> + return rc;
> }
>
> static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
> @@ -579,6 +622,8 @@ nlmsvc_grant_blocked(struct nlm_block *block)
>
> dprintk("lockd: grant blocked lock %p\n", block);
>
> + kref_get(&block->b_count);
> +
> /* Unlink block request from list */
> nlmsvc_unlink_block(block);
>
> @@ -601,11 +646,13 @@ nlmsvc_grant_blocked(struct nlm_block *block)
> case -EAGAIN:
> dprintk("lockd: lock still blocked\n");
> nlmsvc_insert_block(block, NLM_NEVER);
> + nlmsvc_release_block(block);
> return;
> default:
> printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
> -error, __FUNCTION__);
> nlmsvc_insert_block(block, 10 * HZ);
> + nlmsvc_release_block(block);
> return;
> }
>
> @@ -618,7 +665,6 @@ callback:
> nlmsvc_insert_block(block, 30 * HZ);
>
> /* Call the client */
> - kref_get(&block->b_count);
> if (nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
> &nlmsvc_grant_ops) < 0)
> nlmsvc_release_block(block);
> @@ -693,6 +739,23 @@ nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
> nlmsvc_release_block(block);
> }
>
> +/* Helper function to handle retry of a deferred block.
> + * If it is a blocking lock, call grant_blocked.
> + * For a non-blocking lock or test lock, revisit the request.
> + */
> +static void
> +retry_deferred_block(struct nlm_block *block)
> +{
> + if (!(block->b_flags & B_GOT_CALLBACK))
> + block->b_flags |= B_TOO_LATE;
> + nlmsvc_insert_block(block, NLM_TIMEOUT);
> + dprintk("revisit block %p flags %d\n", block, block->b_flags);
> + if (block->b_deferred_req) {
> + block->b_deferred_req->revisit(block->b_deferred_req, 0);
> + block->b_deferred_req = NULL;
> + }
> +}
> +
> /*
> * Retry all blocked locks that have been notified. This is where lockd
> * picks up locks that can be granted, or grant notifications that must
> @@ -716,9 +779,12 @@ nlmsvc_retry_blocked(void)
>
> dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
> block, block->b_when);
> - kref_get(&block->b_count);
> - nlmsvc_grant_blocked(block);
> - nlmsvc_release_block(block);
> + if (block->b_flags & B_QUEUED) {
> + dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
> + block, block->b_granted, block->b_flags);
> + retry_deferred_block(block);
> + } else
> + nlmsvc_grant_blocked(block);
> }
>
> return timeout;
-
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
