Don't ignore the return value from generic_write_sync for the direct to
buffered I/O callback case when written is non-zero.  Also don't bother
to call generic_write_sync for the pure direct I/O case, as iomap_dio_rw
already takes care of that.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 fs/gfs2/file.c | 51 +++++++++++++++++++++++++-------------------------
 1 file changed, 25 insertions(+), 26 deletions(-)

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 21d032c4b077..86c0e61407b6 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -847,7 +847,7 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, 
struct iov_iter *from)
        struct file *file = iocb->ki_filp;
        struct inode *inode = file_inode(file);
        struct gfs2_inode *ip = GFS2_I(inode);
-       ssize_t written = 0, ret;
+       ssize_t ret = 0;
 
        ret = gfs2_rsqa_alloc(ip);
        if (ret)
@@ -882,52 +882,51 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, 
struct iov_iter *from)
                loff_t pos, endbyte;
                ssize_t buffered;
 
-               written = gfs2_file_direct_write(iocb, from);
-               if (written < 0 || !iov_iter_count(from))
+               ret = gfs2_file_direct_write(iocb, from);
+               if (ret < 0 || !iov_iter_count(from))
                        goto out_unlock;
 
                current->backing_dev_info = inode_to_bdi(inode);
-               ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
+               buffered = iomap_file_buffered_write(iocb, from,
+                                                    &gfs2_iomap_ops);
                current->backing_dev_info = NULL;
-               if (unlikely(ret < 0))
+               if (unlikely(buffered <= 0)) {
+                       if (buffered < 0)
+                               ret = buffered;
                        goto out_unlock;
-               buffered = ret;
+               }
 
                /*
                 * We need to ensure that the page cache pages are written to
                 * disk and invalidated to preserve the expected O_DIRECT
-                * semantics.
+                * semantics.  If the writeback or invalidate fails only report
+                * the direct I/O range as we don't know if the buffered pages
+                * made it to disk.
                 */
                pos = iocb->ki_pos;
                endbyte = pos + buffered - 1;
                ret = filemap_write_and_wait_range(mapping, pos, endbyte);
-               if (!ret) {
-                       iocb->ki_pos += buffered;
-                       written += buffered;
-                       invalidate_mapping_pages(mapping,
-                                                pos >> PAGE_SHIFT,
-                                                endbyte >> PAGE_SHIFT);
-               } else {
-                       /*
-                        * We don't know how much we wrote, so just return
-                        * the number of bytes which were direct-written
-                        */
-               }
+               if (ret)
+                       goto out_unlock;
+
+               invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT,
+                                        endbyte >> PAGE_SHIFT);
+               ret += buffered;
        } else {
                current->backing_dev_info = inode_to_bdi(inode);
                ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
                current->backing_dev_info = NULL;
-               if (likely(ret > 0))
-                       iocb->ki_pos += ret;
+               if (unlikely(ret <= 0))
+                       goto out_unlock;
        }
 
+       iocb->ki_pos += ret;
+       inode_unlock(inode);
+       return generic_write_sync(iocb, ret);
+
 out_unlock:
        inode_unlock(inode);
-       if (likely(ret > 0)) {
-               /* Handle various SYNC-type writes */
-               ret = generic_write_sync(iocb, ret);
-       }
-       return written ? written : ret;
+       return ret;
 }
 
 static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,
-- 
2.24.1


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