1 files changed, 31 insertions, 15 deletions

diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index 2db688f94125..03d170b9022b 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -413,12 +413,7 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 	if (streamw)
 		netfs_issue_write(wreq, cache);
 
-	/* Flip the page to the writeback state and unlock.  If we're called
-	 * from write-through, then the page has already been put into the wb
-	 * state.
-	 */
-	if (wreq->origin == NETFS_WRITEBACK)
-		folio_start_writeback(folio);
+	folio_start_writeback(folio);
 	folio_unlock(folio);
 
 	if (fgroup == NETFS_FOLIO_COPY_TO_CACHE) {
@@ -646,29 +641,41 @@ int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_c
 			       struct folio *folio, size_t copied, bool to_page_end,
 			       struct folio **writethrough_cache)
 {
+	int ret;
+
 	_enter("R=%x ic=%zu ws=%u cp=%zu tp=%u",
 	       wreq->debug_id, wreq->buffer.iter.count, wreq->wsize, copied, to_page_end);
 
-	if (!*writethrough_cache) {
-		if (folio_test_dirty(folio))
-			/* Sigh.  mmap. */
-			folio_clear_dirty_for_io(folio);
+	/* The folio is locked. */
 
+	if (*writethrough_cache != folio) {
+		if (*writethrough_cache) {
+			/* Did the folio get moved? */
+			folio_put(*writethrough_cache);
+			*writethrough_cache = NULL;
+		}
 		/* We can make multiple writes to the folio... */
-		folio_start_writeback(folio);
 		if (wreq->len == 0)
 			trace_netfs_folio(folio, netfs_folio_trace_wthru);
 		else
 			trace_netfs_folio(folio, netfs_folio_trace_wthru_plus);
 		*writethrough_cache = folio;
+		folio_get(folio);
 	}
 
 	wreq->len += copied;
-	if (!to_page_end)
+
+	if (!to_page_end) {
+		folio_mark_dirty(folio);
+		folio_unlock(folio);
 		return 0;
+	}
 
+	ret = netfs_write_folio(wreq, wbc, folio);
+	folio_put(*writethrough_cache);
 	*writethrough_cache = NULL;
-	return netfs_write_folio(wreq, wbc, folio);
+	wreq->submitted = wreq->len;
+	return ret;
 }
 
 /*
@@ -682,8 +689,12 @@ ssize_t netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_c
 
 	_enter("R=%x", wreq->debug_id);
 
-	if (writethrough_cache)
+	if (writethrough_cache) {
+		folio_lock(writethrough_cache);
 		netfs_write_folio(wreq, wbc, writethrough_cache);
+		folio_put(writethrough_cache);
+		wreq->submitted = wreq->len;
+	}
 
 	netfs_end_issue_write(wreq);
 
@@ -818,6 +829,9 @@ static int netfs_write_folio_single(struct netfs_io_request *wreq,
  *
  * Write a monolithic, non-pagecache object back to the server and/or
  * the cache.
+ *
+ * Return: 0 if successful; 1 if skipped due to lock conflict and WB_SYNC_NONE;
+ * or a negative error code.
  */
 int netfs_writeback_single(struct address_space *mapping,
 			   struct writeback_control *wbc,
@@ -834,8 +848,10 @@ int netfs_writeback_single(struct address_space *mapping,
 
 	if (!mutex_trylock(&ictx->wb_lock)) {
 		if (wbc->sync_mode == WB_SYNC_NONE) {
+			/* The VFS will have undirtied the inode. */
+			netfs_single_mark_inode_dirty(&ictx->inode);
 			netfs_stat(&netfs_n_wb_lock_skip);
-			return 0;
+			return 1;
 		}
 		netfs_stat(&netfs_n_wb_lock_wait);
 		mutex_lock(&ictx->wb_lock);