Btrfs: Make sure pages are dirty before doing delalloc for them

This adds a PageDirty check to the writeback path that locks pages
for delalloc.  If a page wasn't dirty at this point, it is in the
process of being truncated away.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ad75a9cc3604..69ea09659d47 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1205,7 +1205,8 @@ static noinline int lock_delalloc_pages(struct inode *inode,
                          */
                         if (pages[i] != locked_page) {
                                 lock_page(pages[i]);
-                                if (pages[i]->mapping != inode->i_mapping) {
+                                if (!PageDirty(pages[i]) ||
+                                    pages[i]->mapping != inode->i_mapping) {
                                         ret = -EAGAIN;
                                         unlock_page(pages[i]);
                                         page_cache_release(pages[i]);