On Mon, Oct 05, 2020 at 09:48:41PM -0300, Mauricio Faria de Oliveira wrote: > This implements journal callbacks j_submit|finish_inode_data_buffers() > with different behavior for data=journal: to write-protect pages under > commit, preventing changes to buffers writeably mapped to userspace. > > If a buffer's content changes between commit's checksum calculation > and write-out to disk, it can cause journal recovery/mount failures > upon a kernel crash or power loss. > > [ 27.334874] EXT4-fs: Warning: mounting with data=journal disables delayed allocation, dioread_nolock, and O_DIRECT support! > [ 27.339492] JBD2: Invalid checksum recovering data block 8705 in log > [ 27.342716] JBD2: recovery failed > [ 27.343316] EXT4-fs (loop0): error loading journal > mount: /ext4: can't read superblock on /dev/loop0. > > In j_submit_inode_data_buffers() we write-protect the inode's pages > with write_cache_pages() and redirty w/ writepage callback if needed. > > In j_finish_inode_data_buffers() there is nothing do to. > > And in order to use the callbacks, inodes are added to the inode list > in transaction in __ext4_journalled_writepage() and ext4_page_mkwrite(). > > In ext4_page_mkwrite() we must make sure that the buffers are attached > to the transaction as jbddirty with write_end_fn(), as already done in > __ext4_journalled_writepage(). > > Signed-off-by: Mauricio Faria de Oliveira <mfo@xxxxxxxxxxxxx> > Reported-by: Dann Frazier <dann.frazier@xxxxxxxxxxxxx> > Reported-by: kernel test robot <lkp@xxxxxxxxx> # wbc.nr_to_write > Suggested-by: Jan Kara <jack@xxxxxxx> > Reviewed-by: Jan Kara <jack@xxxxxxx> Thanks, applied. - Ted
