btrfs: reada: avoid undone reada extents in btrfs_reada_wait

[deliverable/linux.git] / fs / eventpoll.c

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 1e009cad8d5cac61832ebb3916033780f2fec1a6..cde60741cad2c4cc429f04e80f29e788b0e0d673 100644 (file)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -92,7 +92,12 @@
  */
 
 /* Epoll private bits inside the event mask */
-#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET)
+#define EP_PRIVATE_BITS (EPOLLWAKEUP | EPOLLONESHOT | EPOLLET | EPOLLEXCLUSIVE)
+
+#define EPOLLINOUT_BITS (POLLIN | POLLOUT)
+
+#define EPOLLEXCLUSIVE_OK_BITS (EPOLLINOUT_BITS | POLLERR | POLLHUP | \
+                               EPOLLWAKEUP | EPOLLET | EPOLLEXCLUSIVE)
 
 /* Maximum number of nesting allowed inside epoll sets */
 #define EP_MAX_NESTS 4
@@ -1002,6 +1007,7 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
        unsigned long flags;
        struct epitem *epi = ep_item_from_wait(wait);
        struct eventpoll *ep = epi->ep;
+       int ewake = 0;
 
        if ((unsigned long)key & POLLFREE) {
                ep_pwq_from_wait(wait)->whead = NULL;
@@ -1066,8 +1072,25 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
         * Wake up ( if active ) both the eventpoll wait list and the ->poll()
         * wait list.
         */
-       if (waitqueue_active(&ep->wq))
+       if (waitqueue_active(&ep->wq)) {
+               if ((epi->event.events & EPOLLEXCLUSIVE) &&
+                                       !((unsigned long)key & POLLFREE)) {
+                       switch ((unsigned long)key & EPOLLINOUT_BITS) {
+                       case POLLIN:
+                               if (epi->event.events & POLLIN)
+                                       ewake = 1;
+                               break;
+                       case POLLOUT:
+                               if (epi->event.events & POLLOUT)
+                                       ewake = 1;
+                               break;
+                       case 0:
+                               ewake = 1;
+                               break;
+                       }
+               }
                wake_up_locked(&ep->wq);
+       }
        if (waitqueue_active(&ep->poll_wait))
                pwake++;
 
@@ -1078,6 +1101,9 @@ out_unlock:
        if (pwake)
                ep_poll_safewake(&ep->poll_wait);
 
+       if (epi->event.events & EPOLLEXCLUSIVE)
+               return ewake;
+
        return 1;
 }
 
@@ -1095,7 +1121,10 @@ static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
                init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
                pwq->whead = whead;
                pwq->base = epi;
-               add_wait_queue(whead, &pwq->wait);
+               if (epi->event.events & EPOLLEXCLUSIVE)
+                       add_wait_queue_exclusive(whead, &pwq->wait);
+               else
+                       add_wait_queue(whead, &pwq->wait);
                list_add_tail(&pwq->llink, &epi->pwqlist);
                epi->nwait++;
        } else {
@@ -1861,6 +1890,19 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
        if (f.file == tf.file || !is_file_epoll(f.file))
                goto error_tgt_fput;
 
+       /*
+        * epoll adds to the wakeup queue at EPOLL_CTL_ADD time only,
+        * so EPOLLEXCLUSIVE is not allowed for a EPOLL_CTL_MOD operation.
+        * Also, we do not currently supported nested exclusive wakeups.
+        */
+       if (epds.events & EPOLLEXCLUSIVE) {
+               if (op == EPOLL_CTL_MOD)
+                       goto error_tgt_fput;
+               if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
+                               (epds.events & ~EPOLLEXCLUSIVE_OK_BITS)))
+                       goto error_tgt_fput;
+       }
+
        /*
         * At this point it is safe to assume that the "private_data" contains
         * our own data structure.
@@ -1932,8 +1974,10 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
                break;
        case EPOLL_CTL_MOD:
                if (epi) {
-                       epds.events |= POLLERR | POLLHUP;
-                       error = ep_modify(ep, epi, &epds);
+                       if (!(epi->event.events & EPOLLEXCLUSIVE)) {
+                               epds.events |= POLLERR | POLLHUP;
+                               error = ep_modify(ep, epi, &epds);
+                       }
                } else
                        error = -ENOENT;
                break;