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    SubjectRe: [linux-pm] Freezer: Don't count threads waiting for frozen filesystems.

    On Wed, 2008-10-29 at 00:12 +0100, Miklos Szeredi wrote:
    > On Wed, 29 Oct 2008, Nigel Cunningham wrote:
    > > > However it does not fix the freezing of tasks which are waiting for
    > > > VFS locks (i.e. inode->i_mutex) held by the outstanding fuse requests.
    > > > This is the tricky part...
    > >
    > > Okay. Looking back on our conversation brought me back to this message,
    > > which I think needs another reply.
    > >
    > > If we take the strategy of holding new requests and allowing existing
    > > ones to complete, then am I right in thinking that we only need to worry
    > > about where inode->i_mutex is taken in fs/fuse/file.c (I don't see it
    > > taken in other fs/fuse/*.c files).
    > Nope, i_mutex is usually taken by the VFS not the filesystem. That
    > means that the filesystem is called with the mutex already held. Try
    > "grep i_mutex fs/*.c". There's also sb->s_vfs_rename_mutex, for all
    > the gory details see Documentation/filesystems/Locking.
    > So it's not just having to fix fuse, it's having to "fix" the VFS as
    > well.

    Remember, though, that we're only freezing fuse at the moment, and
    strictly one filesystem at a time. We can thus happily wait for the
    i_mutex taken by some other process to be released.



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