From ec7d1dbf6dda4f536dbafa966fb111b653948f07 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Thu, 15 Oct 2015 10:29:05 -0400 Subject: [PATCH] ext4: use private version of page_zero_new_buffers() for data=journal mode commit b90197b655185a11640cce3a0a0bc5d8291b8ad2 upstream. If there is a error while copying data from userspace into the page cache during a write(2) system call, in data=journal mode, in ext4_journalled_write_end() were using page_zero_new_buffers() from fs/buffer.c. Unfortunately, this sets the buffer dirty flag, which is no good if journalling is enabled. This is a long-standing bug that goes back for years and years in ext3, but a combination of (a) data=journal not being very common, (b) in many case it only results in a warning message. and (c) only very rarely causes the kernel hang, means that we only really noticed this as a problem when commit 998ef75ddb caused this failure to happen frequently enough to cause generic/208 to fail when run in data=journal mode. The fix is to have our own version of this function that doesn't call mark_dirty_buffer(), since we will end up calling ext4_handle_dirty_metadata() on the buffer head(s) in questions very shortly afterwards in ext4_journalled_write_end(). Thanks to Dave Hansen and Linus Torvalds for helping to identify the root cause of the problem. Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings --- Reading git-format-patch failed