Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:
 "New features for ext4 this cycle include support for encrypted
  casefold, ensure that deleted file names are cleared in directory
  blocks by zeroing directory entries when they are unlinked or moved as
  part of a hash tree node split. We also improve the block allocator's
  performance on a freshly mounted file system by prefetching block
  bitmaps.

  There are also the usual cleanups and bug fixes, including fixing a
  page cache invalidation race when there is mixed buffered and direct
  I/O and the block size is less than page size, and allow the dax flag
  to be set and cleared on inline directories"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (32 commits)
  ext4: wipe ext4_dir_entry2 upon file deletion
  ext4: Fix occasional generic/418 failure
  fs: fix reporting supported extra file attributes for statx()
  ext4: allow the dax flag to be set and cleared on inline directories
  ext4: fix debug format string warning
  ext4: fix trailing whitespace
  ext4: fix various seppling typos
  ext4: fix error return code in ext4_fc_perform_commit()
  ext4: annotate data race in jbd2_journal_dirty_metadata()
  ext4: annotate data race in start_this_handle()
  ext4: fix ext4_error_err save negative errno into superblock
  ext4: fix error code in ext4_commit_super
  ext4: always panic when errors=panic is specified
  ext4: delete redundant uptodate check for buffer
  ext4: do not set SB_ACTIVE in ext4_orphan_cleanup()
  ext4: make prefetch_block_bitmaps default
  ext4: add proc files to monitor new structures
  ext4: improve cr 0 / cr 1 group scanning
  ext4: add MB_NUM_ORDERS macro
  ext4: add mballoc stats proc file
  ...

1 files changed, 21 insertions, 4 deletions

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 5332dd3ea7e22..816dedcbd541e 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -371,15 +371,32 @@ truncate:
 static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
 				 int error, unsigned int flags)
 {
-	loff_t offset = iocb->ki_pos;
+	loff_t pos = iocb->ki_pos;
 	struct inode *inode = file_inode(iocb->ki_filp);
 
 	if (error)
 		return error;
 
-	if (size && flags & IOMAP_DIO_UNWRITTEN)
-		return ext4_convert_unwritten_extents(NULL, inode,
-						      offset, size);
+	if (size && flags & IOMAP_DIO_UNWRITTEN) {
+		error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
+		if (error < 0)
+			return error;
+	}
+	/*
+	 * If we are extending the file, we have to update i_size here before
+	 * page cache gets invalidated in iomap_dio_rw(). Otherwise racing
+	 * buffered reads could zero out too much from page cache pages. Update
+	 * of on-disk size will happen later in ext4_dio_write_iter() where
+	 * we have enough information to also perform orphan list handling etc.
+	 * Note that we perform all extending writes synchronously under
+	 * i_rwsem held exclusively so i_size update is safe here in that case.
+	 * If the write was not extending, we cannot see pos > i_size here
+	 * because operations reducing i_size like truncate wait for all
+	 * outstanding DIO before updating i_size.
+	 */
+	pos += size;
+	if (pos > i_size_read(inode))
+		i_size_write(inode, pos);
 
 	return 0;
 }