Merge tag 'nfs-for-3.17-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client fixes from Trond Myklebust:
 "Highlights:

   - more fixes for read/write codepath regressions
     * sleeping while holding the inode lock
     * stricter enforcement of page contiguity when coalescing requests
     * fix up error handling in the page coalescing code

   - don't busy wait on SIGKILL in the file locking code"

* tag 'nfs-for-3.17-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  nfs: Don't busy-wait on SIGKILL in __nfs_iocounter_wait
  nfs: can_coalesce_requests must enforce contiguity
  nfs: disallow duplicate pages in pgio page vectors
  nfs: don't sleep with inode lock in lock_and_join_requests
  nfs: fix error handling in lock_and_join_requests
  nfs: use blocking page_group_lock in add_request
  nfs: fix nonblocking calls to nfs_page_group_lock
  nfs: change nfs_page_group_lock argument

1 files changed, 17 insertions, 4 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index e3b5cf28bdc5..175d5d073ccf 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -241,7 +241,7 @@ static bool nfs_page_group_covers_page(struct nfs_page *req)
 	unsigned int pos = 0;
 	unsigned int len = nfs_page_length(req->wb_page);
 
-	nfs_page_group_lock(req, true);
+	nfs_page_group_lock(req, false);
 
 	do {
 		tmp = nfs_page_group_search_locked(req->wb_head, pos);
@@ -478,10 +478,23 @@ try_again:
 		return NULL;
 	}
 
-	/* lock each request in the page group */
-	ret = nfs_page_group_lock(head, false);
-	if (ret < 0)
+	/* holding inode lock, so always make a non-blocking call to try the
+	 * page group lock */
+	ret = nfs_page_group_lock(head, true);
+	if (ret < 0) {
+		spin_unlock(&inode->i_lock);
+
+		if (!nonblock && ret == -EAGAIN) {
+			nfs_page_group_lock_wait(head);
+			nfs_release_request(head);
+			goto try_again;
+		}
+
+		nfs_release_request(head);
 		return ERR_PTR(ret);
+	}
+
+	/* lock each request in the page group */
 	subreq = head;
 	do {
 		/*