1 files changed, 134 insertions, 142 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index c478b772cc49..df4b87c30ac9 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -149,6 +149,31 @@ static void nfs_io_completion_put(struct nfs_io_completion *ioc)
 		kref_put(&ioc->refcount, nfs_io_completion_release);
 }
 
+static void
+nfs_page_set_inode_ref(struct nfs_page *req, struct inode *inode)
+{
+	if (!test_and_set_bit(PG_INODE_REF, &req->wb_flags)) {
+		kref_get(&req->wb_kref);
+		atomic_long_inc(&NFS_I(inode)->nrequests);
+	}
+}
+
+static int
+nfs_cancel_remove_inode(struct nfs_page *req, struct inode *inode)
+{
+	int ret;
+
+	if (!test_bit(PG_REMOVE, &req->wb_flags))
+		return 0;
+	ret = nfs_page_group_lock(req);
+	if (ret)
+		return ret;
+	if (test_and_clear_bit(PG_REMOVE, &req->wb_flags))
+		nfs_page_set_inode_ref(req, inode);
+	nfs_page_group_unlock(req);
+	return 0;
+}
+
 static struct nfs_page *
 nfs_page_private_request(struct page *page)
 {
@@ -218,6 +243,36 @@ static struct nfs_page *nfs_page_find_head_request(struct page *page)
 	return req;
 }
 
+static struct nfs_page *nfs_find_and_lock_page_request(struct page *page)
+{
+	struct inode *inode = page_file_mapping(page)->host;
+	struct nfs_page *req, *head;
+	int ret;
+
+	for (;;) {
+		req = nfs_page_find_head_request(page);
+		if (!req)
+			return req;
+		head = nfs_page_group_lock_head(req);
+		if (head != req)
+			nfs_release_request(req);
+		if (IS_ERR(head))
+			return head;
+		ret = nfs_cancel_remove_inode(head, inode);
+		if (ret < 0) {
+			nfs_unlock_and_release_request(head);
+			return ERR_PTR(ret);
+		}
+		/* Ensure that nobody removed the request before we locked it */
+		if (head == nfs_page_private_request(page))
+			break;
+		if (PageSwapCache(page))
+			break;
+		nfs_unlock_and_release_request(head);
+	}
+	return head;
+}
+
 /* Adjust the file length if we're writing beyond the end */
 static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int count)
 {
@@ -380,34 +435,6 @@ static void nfs_end_page_writeback(struct nfs_page *req)
 }
 
 /*
- * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
- *
- * this is a helper function for nfs_lock_and_join_requests
- *
- * @inode - inode associated with request page group, must be holding inode lock
- * @head  - head request of page group, must be holding head lock
- * @req   - request that couldn't lock and needs to wait on the req bit lock
- *
- * NOTE: this must be called holding page_group bit lock
- *       which will be released before returning.
- *
- * returns 0 on success, < 0 on error.
- */
-static void
-nfs_unroll_locks(struct inode *inode, struct nfs_page *head,
-			  struct nfs_page *req)
-{
-	struct nfs_page *tmp;
-
-	/* relinquish all the locks successfully grabbed this run */
-	for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
-		if (!kref_read(&tmp->wb_kref))
-			continue;
-		nfs_unlock_and_release_request(tmp);
-	}
-}
-
-/*
  * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
  *
  * @destroy_list - request list (using wb_this_page) terminated by @old_head
@@ -428,22 +455,29 @@ nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 		destroy_list = (subreq->wb_this_page == old_head) ?
 				   NULL : subreq->wb_this_page;
 
+		/* Note: lock subreq in order to change subreq->wb_head */
+		nfs_page_set_headlock(subreq);
 		WARN_ON_ONCE(old_head != subreq->wb_head);
 
 		/* make sure old group is not used */
 		subreq->wb_this_page = subreq;
+		subreq->wb_head = subreq;
 
 		clear_bit(PG_REMOVE, &subreq->wb_flags);
 
 		/* Note: races with nfs_page_group_destroy() */
 		if (!kref_read(&subreq->wb_kref)) {
 			/* Check if we raced with nfs_page_group_destroy() */
-			if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags))
+			if (test_and_clear_bit(PG_TEARDOWN, &subreq->wb_flags)) {
+				nfs_page_clear_headlock(subreq);
 				nfs_free_request(subreq);
+			} else
+				nfs_page_clear_headlock(subreq);
 			continue;
 		}
+		nfs_page_clear_headlock(subreq);
 
-		subreq->wb_head = subreq;
+		nfs_release_request(old_head);
 
 		if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags)) {
 			nfs_release_request(subreq);
@@ -457,105 +491,43 @@ nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
 }
 
 /*
- * nfs_lock_and_join_requests - join all subreqs to the head req and return
- *                              a locked reference, cancelling any pending
- *                              operations for this page.
- *
- * @page - the page used to lookup the "page group" of nfs_page structures
+ * nfs_join_page_group - destroy subrequests of the head req
+ * @head: the page used to lookup the "page group" of nfs_page structures
+ * @inode: Inode to which the request belongs.
  *
  * This function joins all sub requests to the head request by first
  * locking all requests in the group, cancelling any pending operations
  * and finally updating the head request to cover the whole range covered by
  * the (former) group.  All subrequests are removed from any write or commit
  * lists, unlinked from the group and destroyed.
- *
- * Returns a locked, referenced pointer to the head request - which after
- * this call is guaranteed to be the only request associated with the page.
- * Returns NULL if no requests are found for @page, or a ERR_PTR if an
- * error was encountered.
  */
-static struct nfs_page *
-nfs_lock_and_join_requests(struct page *page)
+void
+nfs_join_page_group(struct nfs_page *head, struct inode *inode)
 {
-	struct inode *inode = page_file_mapping(page)->host;
-	struct nfs_page *head, *subreq;
+	struct nfs_page *subreq;
 	struct nfs_page *destroy_list = NULL;
-	unsigned int total_bytes;
-	int ret;
+	unsigned int pgbase, off, bytes;
 
-try_again:
-	/*
-	 * A reference is taken only on the head request which acts as a
-	 * reference to the whole page group - the group will not be destroyed
-	 * until the head reference is released.
-	 */
-	head = nfs_page_find_head_request(page);
-	if (!head)
-		return NULL;
-
-	/* lock the page head first in order to avoid an ABBA inefficiency */
-	if (!nfs_lock_request(head)) {
-		ret = nfs_wait_on_request(head);
-		nfs_release_request(head);
-		if (ret < 0)
-			return ERR_PTR(ret);
-		goto try_again;
-	}
-
-	/* Ensure that nobody removed the request before we locked it */
-	if (head != nfs_page_private_request(page) && !PageSwapCache(page)) {
-		nfs_unlock_and_release_request(head);
-		goto try_again;
-	}
-
-	ret = nfs_page_group_lock(head);
-	if (ret < 0)
-		goto release_request;
-
-	/* lock each request in the page group */
-	total_bytes = head->wb_bytes;
+	pgbase = head->wb_pgbase;
+	bytes = head->wb_bytes;
+	off = head->wb_offset;
 	for (subreq = head->wb_this_page; subreq != head;
 			subreq = subreq->wb_this_page) {
-
-		if (!kref_get_unless_zero(&subreq->wb_kref)) {
-			if (subreq->wb_offset == head->wb_offset + total_bytes)
-				total_bytes += subreq->wb_bytes;
-			continue;
-		}
-
-		while (!nfs_lock_request(subreq)) {
-			/*
-			 * Unlock page to allow nfs_page_group_sync_on_bit()
-			 * to succeed
-			 */
-			nfs_page_group_unlock(head);
-			ret = nfs_wait_on_request(subreq);
-			if (!ret)
-				ret = nfs_page_group_lock(head);
-			if (ret < 0) {
-				nfs_unroll_locks(inode, head, subreq);
-				nfs_release_request(subreq);
-				goto release_request;
-			}
-		}
-		/*
-		 * Subrequests are always contiguous, non overlapping
-		 * and in order - but may be repeated (mirrored writes).
-		 */
-		if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
-			/* keep track of how many bytes this group covers */
-			total_bytes += subreq->wb_bytes;
-		} else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
-			    ((subreq->wb_offset + subreq->wb_bytes) >
-			     (head->wb_offset + total_bytes)))) {
-			nfs_page_group_unlock(head);
-			nfs_unroll_locks(inode, head, subreq);
-			nfs_unlock_and_release_request(subreq);
-			ret = -EIO;
-			goto release_request;
+		/* Subrequests should always form a contiguous range */
+		if (pgbase > subreq->wb_pgbase) {
+			off -= pgbase - subreq->wb_pgbase;
+			bytes += pgbase - subreq->wb_pgbase;
+			pgbase = subreq->wb_pgbase;
 		}
+		bytes = max(subreq->wb_pgbase + subreq->wb_bytes
+				- pgbase, bytes);
 	}
 
+	/* Set the head request's range to cover the former page group */
+	head->wb_pgbase = pgbase;
+	head->wb_bytes = bytes;
+	head->wb_offset = off;
+
 	/* Now that all requests are locked, make sure they aren't on any list.
 	 * Commit list removal accounting is done after locks are dropped */
 	subreq = head;
@@ -569,36 +541,52 @@ try_again:
 		/* destroy list will be terminated by head */
 		destroy_list = head->wb_this_page;
 		head->wb_this_page = head;
-
-		/* change head request to cover whole range that
-		 * the former page group covered */
-		head->wb_bytes = total_bytes;
 	}
 
-	/* Postpone destruction of this request */
-	if (test_and_clear_bit(PG_REMOVE, &head->wb_flags)) {
-		set_bit(PG_INODE_REF, &head->wb_flags);
-		kref_get(&head->wb_kref);
-		atomic_long_inc(&NFS_I(inode)->nrequests);
-	}
+	nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
+}
 
-	nfs_page_group_unlock(head);
+/*
+ * nfs_lock_and_join_requests - join all subreqs to the head req
+ * @page: the page used to lookup the "page group" of nfs_page structures
+ *
+ * This function joins all sub requests to the head request by first
+ * locking all requests in the group, cancelling any pending operations
+ * and finally updating the head request to cover the whole range covered by
+ * the (former) group.  All subrequests are removed from any write or commit
+ * lists, unlinked from the group and destroyed.
+ *
+ * Returns a locked, referenced pointer to the head request - which after
+ * this call is guaranteed to be the only request associated with the page.
+ * Returns NULL if no requests are found for @page, or a ERR_PTR if an
+ * error was encountered.
+ */
+static struct nfs_page *
+nfs_lock_and_join_requests(struct page *page)
+{
+	struct inode *inode = page_file_mapping(page)->host;
+	struct nfs_page *head;
+	int ret;
 
-	nfs_destroy_unlinked_subrequests(destroy_list, head, inode);
+	/*
+	 * A reference is taken only on the head request which acts as a
+	 * reference to the whole page group - the group will not be destroyed
+	 * until the head reference is released.
+	 */
+	head = nfs_find_and_lock_page_request(page);
+	if (IS_ERR_OR_NULL(head))
+		return head;
 
-	/* Did we lose a race with nfs_inode_remove_request()? */
-	if (!(PagePrivate(page) || PageSwapCache(page))) {
+	/* lock each request in the page group */
+	ret = nfs_page_group_lock_subrequests(head);
+	if (ret < 0) {
 		nfs_unlock_and_release_request(head);
-		return NULL;
+		return ERR_PTR(ret);
 	}
 
-	/* still holds ref on head from nfs_page_find_head_request
-	 * and still has lock on head from lock loop */
-	return head;
+	nfs_join_page_group(head, inode);
 
-release_request:
-	nfs_unlock_and_release_request(head);
-	return ERR_PTR(ret);
+	return head;
 }
 
 static void nfs_write_error(struct nfs_page *req, int error)
@@ -1707,7 +1695,7 @@ int nfs_initiate_commit(struct rpc_clnt *clnt, struct nfs_commit_data *data,
 		.callback_ops = call_ops,
 		.callback_data = data,
 		.workqueue = nfsiod_workqueue,
-		.flags = RPC_TASK_ASYNC | flags,
+		.flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF | flags,
 		.priority = priority,
 	};
 	/* Set up the initial task struct.  */
@@ -1746,14 +1734,19 @@ void nfs_init_commit(struct nfs_commit_data *data,
 		     struct pnfs_layout_segment *lseg,
 		     struct nfs_commit_info *cinfo)
 {
-	struct nfs_page *first = nfs_list_entry(head->next);
-	struct nfs_open_context *ctx = nfs_req_openctx(first);
-	struct inode *inode = d_inode(ctx->dentry);
+	struct nfs_page *first;
+	struct nfs_open_context *ctx;
+	struct inode *inode;
 
 	/* Set up the RPC argument and reply structs
 	 * NB: take care not to mess about with data->commit et al. */
 
-	list_splice_init(head, &data->pages);
+	if (head)
+		list_splice_init(head, &data->pages);
+
+	first = nfs_list_entry(data->pages.next);
+	ctx = nfs_req_openctx(first);
+	inode = d_inode(ctx->dentry);
 
 	data->inode	  = inode;
 	data->cred	  = ctx->cred;
@@ -1869,8 +1862,7 @@ static void nfs_commit_release_pages(struct nfs_commit_data *data)
 
 		/* Okay, COMMIT succeeded, apparently. Check the verifier
 		 * returned by the server against all stored verfs. */
-		if (verf->committed > NFS_UNSTABLE &&
-		    !nfs_write_verifier_cmp(&req->wb_verf, &verf->verifier)) {
+		if (nfs_write_match_verf(verf, req)) {
 			/* We have a match */
 			if (req->wb_page)
 				nfs_inode_remove_request(req);