Merge tag 'for-linus-4.14c-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel...

[sfrench/cifs-2.6.git] / fs / direct-io.c

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 563254869e2fa4fa62bd91a58d9524a5180bc5ef..b53e66d9abd7030f6b05a6dac4847928c24bf1a0 100644 (file)
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -265,12 +265,24 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
        if (ret == 0)
                ret = transferred;
 
+       if (dio->end_io) {
+               // XXX: ki_pos??
+               err = dio->end_io(dio->iocb, offset, ret, dio->private);
+               if (err)
+                       ret = err;
+       }
+
        /*
         * Try again to invalidate clean pages which might have been cached by
         * non-direct readahead, or faulted in by get_user_pages() if the source
         * of the write was an mmap'ed region of the file we're writing.  Either
         * one is a pretty crazy thing to do, so we don't support it 100%.  If
         * this invalidation fails, tough, the write still worked...
+        *
+        * And this page cache invalidation has to be after dio->end_io(), as
+        * some filesystems convert unwritten extents to real allocations in
+        * end_io() when necessary, otherwise a racing buffer read would cache
+        * zeros from unwritten extents.
         */
        if (flags & DIO_COMPLETE_INVALIDATE &&
            ret > 0 && dio->op == REQ_OP_WRITE &&
@@ -281,14 +293,6 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
                WARN_ON_ONCE(err);
        }
 
-       if (dio->end_io) {
-
-               // XXX: ki_pos??
-               err = dio->end_io(dio->iocb, offset, ret, dio->private);
-               if (err)
-                       ret = err;
-       }
-
        if (!(dio->flags & DIO_SKIP_DIO_COUNT))
                inode_dio_end(dio->inode);