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    SubjectRe: [PATCH 4/6] fuse: enable close_wait synchronous release
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    On Thu, Aug 21, 2014 at 6:09 PM, Maxim Patlasov <MPatlasov@parallels.com> wrote:
    > The patch enables the feature by passing 'true' to fuse_file_put in
    > fuse_release_common.
    >
    > Previously, this was safe only in special cases when we sure that
    > multi-threaded userspace won't deadlock if we'll synchronously send
    > FUSE_RELEASE in the context of read-ahead or write-back callback. Now, it's
    > always safe because callbacks don't send requests to userspace anymore.

    But we do want to make this privileged, as there are unlikely but
    possible DoS scenarios with a sync release.

    Thanks,
    Miklos

    >
    > Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
    > ---
    > fs/fuse/file.c | 3 ++-
    > 1 file changed, 2 insertions(+), 1 deletion(-)
    >
    > diff --git a/fs/fuse/file.c b/fs/fuse/file.c
    > index 73bce1b..cd55488 100644
    > --- a/fs/fuse/file.c
    > +++ b/fs/fuse/file.c
    > @@ -333,7 +333,8 @@ void fuse_release_common(struct file *file, int opcode)
    > * synchronous RELEASE is allowed (and desirable) in this case
    > * because the server can be trusted not to screw up.
    > */
    > - fuse_file_put(ff, ff->fc->destroy_req != NULL);
    > + fuse_file_put(ff, ff->fc->destroy_req != NULL ||
    > + must_release_synchronously(ff));
    > }
    >
    > static int fuse_open(struct inode *inode, struct file *file)
    >


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