On Tue, 4 Mar 2014, Theodore Ts'o wrote: > Date: Tue, 4 Mar 2014 10:19:25 -0500 > From: Theodore Ts'o <tytso@xxxxxxx> > To: Lukáš Czerner <lczerner@xxxxxxxxxx> > Cc: Eryu Guan <guaneryu@xxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] mke2fs: disable resize_inode feature if 64bit feature is > enabled > > On Mon, Mar 03, 2014 at 04:40:21PM +0100, Lukáš Czerner wrote: > > > > are you going to take this in ? > > > > > It's better to use the resize_inode for file systems that are smaller > > > than 16TB, even if the 64-bit flag is enabled, since using the meta_bg > > > style resizing spreads out the block group descriptors, which > > > increases the time to mount the file system. Using the resize_inode > > > will defer the need to go to the meta_bg-style resizing until we cross > > > the 16TB boundary. > > See my comments above. > > If we create a file system which is say, 1T but with the 64-bit flag, > we do want the resize_inode feature to be used until we cross over the > 32-bit boundary, because keeping block group descriptors contiguous > speeds up the mount time. > > If I were to accept this patch, and/or Red Hat were to ship with it, I > will predict that you will get angry customer support calls about file > system mount times getting slow after doing a resize. > > At some point what we may want to lazily load the block group > descriptors at mount time, to mitigate the slow mount time issue when > using meta_bg. We have a lot of assumptions in the code that the > block group descriptors are always available, though. > > - Ted Hi Ted, I am sorry, but am I missing something ? This patch seems to do exactly that. if ((fs_blocks_count > MAX_32_NUM) && + (fs_param.s_feature_incompat & EXT4_FEATURE_INCOMPAT_64BIT)) + fs_param.s_feature_compat &= ~EXT2_FEATURE_COMPAT_RESIZE_INODE; The answer from you on that patch is commenting on a guestion from Zheng Liu who is asking whether we could skip the MAX_32_NUM check. So the patch seems to be ok for me. Thanks! -Lukas
