ext4: always re-base nr_to_write in ext4_da_writepages When ext4_da_writepages increases the nr_to_write in writeback_control then it must always re-base the return value. Without this change, when wb_writeback calculates how many pages were actually written it can get a negative value and loop more times than necessary. In tests I have seen nearly all the dirty pages pushed out to writeback due to this issue. Signed-off-by: Richard Kennedy <richard@xxxxxxxxxxxxxxx> ---- patch against 2.6.32 tested on x86_64 wb_writeback calculates (MAX_WRITE_PAGES - nr_to_write) & cannot know that the value got changed. I'm not sure what the test I removed was for. Perhaps if (nr_to_writebump) wbc->nr_to_write -= nr_to_writebump; was intended? regards Richard diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 2c8caa5..52a573c 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2999,8 +2999,7 @@ retry: out_writepages: if (!no_nrwrite_index_update) wbc->no_nrwrite_index_update = 0; - if (wbc->nr_to_write > nr_to_writebump) - wbc->nr_to_write -= nr_to_writebump; + wbc->nr_to_write -= nr_to_writebump; wbc->range_start = range_start; trace_ext4_da_writepages_result(inode, wbc, ret, pages_written); return ret; -- 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
