lkml.org 
[lkml]   [2012]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Subject[PATCH v2 v2 0/4] do not use s_dirt in FAT FS
    Date
    This is version 2 of the patch-set which makes FAT file-system stop using
    the VFS '->write_super()' method for writing out the FSINFO block. The fist
    version can be found here: http://lkml.org/lkml/2012/4/11/147

    Comparing to v1, this patch takes a completely different approach. Instead of
    using a delayed job, we introduce a special inode for the FSINFO block, mark
    it as dirty when needed, and use generic inode write-back mechanisms to write
    the FSINFO block via '->write_inode()'. I think this is much cleaner.

    Let me recap why I am doing this, and the current status of this exercises.

    The final goal is to get rid of the 'sync_supers()' kernel thread. This kernel
    thread wakes up every 5 seconds (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.

    The '->write_supers()' method is mostly used by baroque file-systems like hfs,
    udf, etc. Modern file-systems like btrfs and xfs do not use it. This justifies
    removing this stuff from VFS completely and make every FS self-manage own
    superblock.

    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, see http://lkml.org/lkml/2010/7/22/96

    ======
    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
    ======

    fs/fat/fat.h | 1 +
    fs/fat/fatent.c | 22 +++++++++++++-----
    fs/fat/inode.c | 54 ++++++++++++++++++++-------------------------
    include/linux/msdos_fs.h | 3 +-
    4 files changed, 43 insertions(+), 37 deletions(-)

    Thanks,
    Artem.


    \
     
     \ /
      Last update: 2012-04-13 16:21    [W:2.291 / U:0.120 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site