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    SubjectRe: [patch 26/35] fs: icache alloc anonymous inode allocation
    On Tue, Oct 19, 2010 at 12:33:27PM -0400, Christoph Hellwig wrote:
    > On Tue, Oct 19, 2010 at 02:42:42PM +1100, npiggin@kernel.dk wrote:
    > > Provide new_anon_inode function for inodes without a default inode number, and
    > > not on sb list. This can enable filesystems to reduce locking. "Real"
    > > filesystems can also reduce locking by allocating anonymous inode first, then
    > > adding it to lists after finding the inode number.
    >
    > Having an _anon inode allocation for fileystsem that do manage the inode
    > lifetime is fine, but please don't mix that up with i_ino assignment,
    > as they are two totally different things.
    >
    > Disk and network filesystem do not need a default i_ino, but they
    > absolutely do no need their inodes to be on the per-sb list.
    > anonfs/pipe/socket (and nothing else) can do away with the per-sb list,
    > but they do need a pseudo inode number.

    Probably bad wording of "anon". It should be "raw", maybe. The
    filesystem is then of course responsible for adding i_ino and/or
    to lists.


    > I have a version of this port to Dave's tree which gets this right.
    > i_ino assignment is already moved out by my patch (which should apply
    > to your tree with minimal differences), so the new _anon only does not
    > put the inode on the list. The other difference is that we don't bother
    > initializing i_sb_list in the main inode allocation path, but only in
    > new_anon_inode, and that the function is not exported - it really should
    > only be used for built-in filesystems that never get unmounted to be
    > safe.

    I'll check it.



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