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    fs/locks.c: prepare for BKL removal · b89f4321
    Arnd Bergmann 提交于
    This prepares the removal of the big kernel lock from the
    file locking code. We still use the BKL as long as fs/lockd
    uses it and ceph might sleep, but we can flip the definition
    to a private spinlock as soon as that's done.
    All users outside of fs/lockd get converted to use
    lock_flocks() instead of lock_kernel() where appropriate.
    
    Based on an earlier patch to use a spinlock from Matthew
    Wilcox, who has attempted this a few times before, the
    earliest patch from over 10 years ago turned it into
    a semaphore, which ended up being slower than the BKL
    and was subsequently reverted.
    
    Someone should do some serious performance testing when
    this becomes a spinlock, since this has caused problems
    before. Using a spinlock should be at least as good
    as the BKL in theory, but who knows...
    Signed-off-by: NArnd Bergmann <arnd@arndb.de>
    Acked-by: NMatthew Wilcox <willy@linux.intel.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
    Cc: "J. Bruce Fields" <bfields@fieldses.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Miklos Szeredi <mszeredi@suse.cz>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: John Kacur <jkacur@redhat.com>
    Cc: Sage Weil <sage@newdream.net>
    Cc: linux-kernel@vger.kernel.org
    Cc: linux-fsdevel@vger.kernel.org
    b89f4321
nfs4state.c 111.3 KB