On Tue, 04 Nov 2014 16:50:21 +0100, Andreas Rohner wrote: > On 2014-11-04 15:34, Ryusuke Konishi wrote: >> Since each call to nilfs_construct_segment() or >> nilfs_construct_dsync_segment() implies an IO completion wait, it >> seems that this doubles the latency of fsync(). >> >> Do you really need to call filemap_write_and_wait_range() in >> nilfs_sync_file() ? > > I don't think we need it, but I found the following paragraph in > Documentation/filesystems/porting: > > [mandatory] > If you have your own ->fsync() you must make sure to call > filemap_write_and_wait_range() so that all dirty pages are synced out > properly. You must also keep in mind that ->fsync() is not called with > i_mutex held anymore, so if you require i_mutex locking you must make > sure to take it and release it yourself. > > So I was unsure, if it is safe to remove it. But maybe I interpreted > that wrongly, since nilfs_construct_dsync_segment() and > nilfs_construct_segment() write out all dirty pages anyway, there is no > need for filemap_write_and_wait_range(). I found filemap_write_and_wait_range() returns error status of already done page I/Os via filemap_check_errors(). We need to look into what it does. > Also do we need i_mutex? As far as I can tell all relevant code blocks > are wrapped in nilfs_transaction_begin/commit/abort(). Yes, we may also remove the i_mutex. We have to confirm what i_mutex protects for nilfs. Regards, Ryusuke Konishi -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
