The FAT file-system uses the VFS '->write_super()' method for writing out the FSINFO block, which contains useful but not critical information like the amount of free clusters. This patch-set makes FAT FS use its own mechanisms for writing-out the FSINFO block and stop using the '->write_super()' VFS method. Namely, the FAT FS now submits a delayed work for writing out the FSINFO block once it becomes dirty. The reason of this exercises is to get rid of the 'sync_supers()' kernel thread. This kernel thread wakes up every 5 (by default) and calls '->write_super()' for all mounted file-systems. And the bad thing is that this is done even if all the superblocks are clean. Moreover, some file-systems do not even need this end they do not register the '->write_super()' method at all (e.g., btrfs). So 'sync_supers()' most often just generates useless wake-ups and wastes power. I am trying to make all file-systems independent of '->write_super()' and plan to remove 'sync_supers()' and '->write_super' completely once there are no more users. Tested with xfstests. Note: in the past I was trying to upstream patches which optimized 'sync_super()', but Al Viro wanted me to kill it completely instead, which I am trying to do now. ====== Overall status: 1. ext4: patches submitted, waiting for reply from Ted Ts'o: https://lkml.org/lkml/2012/4/2/111 2. ext2: patches are in the ext2 tree maintained by Jan Kara: git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git for_next However, one patch is still not there: http://www.spinics.net/lists/linux-ext4/msg31492.html TODO: affs, exofs, hfs, hfsplus, jffs2, reiserfs, sysv, udf, ufs ====== Thanks, Artem. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
