Revert "ext4: use ext4_write_inode() when fsyncing w/o a journal"

tytso · tytso · commit 8fdd60f2ae36 · 2019-01-31T23:41:11.000-05:00
This reverts commit ad211f3. As Jan Kara pointed out, this change was unsafe since it means we lose the call to sync_mapping_buffers() in the nojournal case. The original point of the commit was avoid taking the inode mutex (since it causes a lockdep warning in generic/113); but we need the mutex in order to call sync_mapping_buffers(). The real fix to this problem was discussed here: https://lore.kernel.org/lkml/20181025150540.259281-4-bvanassche@acm.org The proposed patch was to fix a syzbot complaint, but the problem can also demonstrated via "kvm-xfstests -c nojournal generic/113". Multiple solutions were discused in the e-mail thread, but none have landed in the kernel as of this writing. Anyway, commit ad211f3 is absolutely the wrong way to suppress the lockdep, so revert it. Fixes: ad211f3 ("ext4: use ext4_write_inode() when fsyncing w/o a journal") Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reported: Jan Kara <jack@suse.cz>
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
@@ -116,23 +116,18 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 		goto out;
 	}
 
-	ret = file_write_and_wait_range(file, start, end);
-	if (ret)
-		return ret;
-
 	if (!journal) {
-		struct writeback_control wbc = {
-			.sync_mode = WB_SYNC_ALL
-		};
-
-		ret = ext4_write_inode(inode, &wbc);
+		ret = __generic_file_fsync(file, start, end, datasync);
 		if (!ret)
 			ret = ext4_sync_parent(inode);
 		if (test_opt(inode->i_sb, BARRIER))
 			goto issue_flush;
 		goto out;
 	}
 
+	ret = file_write_and_wait_range(file, start, end);
+	if (ret)
+		return ret;
 	/*
 	 * data=writeback,ordered:
 	 *  The caller's filemap_fdatawrite()/wait will sync the data.
