On Mon, Aug 05, 2013 at 03:52:22PM +0200, Jan Kara wrote: > Inode size can arbitrarily change while writeback is in progress. When > ext4_writepages() has prepared a long extent for mapping and truncate > then reduces i_size, mpage_map_and_submit_buffers() will always map just > one buffer in a page instead of all of them due to lblk < blocks check. > So we end up not using all blocks we've allocated (thus leaking them) > and also delalloc accounting goes wrong manifesting as a warning like: > > ext4_da_release_space:1333: ext4_da_release_space: ino 12, to_free 1 > with only 0 reserved data blocks > > Note that the problem can happen only when blocksize < pagesize because > otherwise we have only a single buffer in the page. > > Fix the problem by removing the size check from the mapping loop. We > have an extent allocated so we have to use it all before checking for > i_size. We also rename add_page_bufs_to_extent() to > mpage_process_page_bufs() and make that function submit the page for IO > if all buffers (upto EOF) in it are mapped. > > Reported-by: Dave Jones <davej@xxxxxxxxxx> > Reported-by: Zheng Liu <gnehzuil.liu@xxxxxxxxx> > Signed-off-by: Jan Kara <jack@xxxxxxx> Thanks, applied. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
