[Patch 0/10]: Cleanup online reservations for 2.6.9-rc2-mm4.

From: Stephen Tweedie (sct_at_redhat.com)
Date: 09/30/04

  • Next message: Stephen Tweedie: "[Patch 3/10]: ext3 online resize: fix bh leak" 
    Date:	Thu, 30 Sep 2004 14:23:10 +0100
To: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>, Andreas Dilger <adilger@clusterfs.com>, "Theodore Ts'o" <tytso@mit.edu>, ext2-devel@lists.sourceforge.net

    The patches to follow clean up a lot of the ext3 online reservation
    code in 2.6.9-rc2-mm4. There are a few minor fixes for things like
    loglevels of printks and correcting some error returns, plus
    refactoring a bit of existing ext3 code to allow resize to avoid dummy
    on-stack inodes.

    There's also a review of the whole SMP locking of the resize. Locking
    is minimised: the impact on the hot path consists of nothing more than
    an smp_rmb() before we test sb->s_groups_count. That's a noop on x86,
    but is a bit expensive on archs with a weak memory order; I've tried to
    minimise that by reading it just once where previously it was read each
    time round a loop, but I don't see how to avoid the cost entirely.

    Finally, sb->s_debts is nuked from ext3. It's broken already, as per my
    email a week or two ago --- the per-group s_debt[] counts never get
    modified. We could probably do with nuking it from ext2 too, as it's
    (differently) broken there (performs unlocked byte inc/dec operations on
    a shared array and is vulnerable to word-tearing problems.)

    This should address all of the points akpm had in his review of resize
    a while back, except for the documentation/user space side of things
    and the lack of error checking in certain ext3_journal_dirty_metadata
    calls: I'm still fixing those up (I'll try to push out a working
    user-space for this later today.)

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