• Linus Torvalds's avatar
    Revert "ext2/ext3/ext4: add block bitmap validation" · 0b832a4b
    Linus Torvalds authored
    This reverts commit 7c9e69fa, fixing up
    conflicts in fs/ext4/balloc.c manually.
    
    The cost of doing the bitmap validation on each lookup - even when the
    bitmap is cached - is absolutely prohibitive.  We could, and probably
    should, do it only when adding the bitmap to the buffer cache.  However,
    right now we are better off just reverting it.
    
    Peter Zijlstra measured the cost of this extra validation as a 85%
    decrease in cached iozone, and while I had a patch that took it down to
    just 17% by not being _quite_ so stupid in the validation, it was still
    a big slowdown that could have been avoided by just doing it right.
    
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
    Cc: Andreas Dilger <adilger@clusterfs.com>
    Cc: Mingming Cao <cmm@us.ibm.com>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    0b832a4b
balloc.c 42.7 KB