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SubjectRe: [fuse-devel] [PATCH 0/5] fuse: close file synchronously
Hi Miklos,

Any feedback would be highly appreciated.

Thanks,
Maxim

12/20/2012 04:30 PM, Maxim Patlasov пишет:
> Hi,
>
> There is a long-standing demand for syncronous behaviour of fuse_release:
>
> http://sourceforge.net/mailarchive/message.php?msg_id=19343889
> http://sourceforge.net/mailarchive/message.php?msg_id=29814693
>
> A few months ago Avati and me explained why such a feature would be useful:
>
> http://sourceforge.net/mailarchive/message.php?msg_id=29889055
> http://sourceforge.net/mailarchive/message.php?msg_id=29867423
>
> In short, the problem is that fuse_release (that's called on last user
> close(2)) sends FUSE_RELEASE to userspace and returns without waiting for
> ACK from userspace. Consequently, there is a gap when user regards the
> file released while userspace fuse is still working on it. An attempt to
> access the file from another node leads to complicated synchronization
> problems because the first node still "holds" the file.
>
> The patch-set resolves the problem by making fuse_release synchronous:
> wait for ACK from userspace for FUSE_RELEASE if the feature is ON.
>
> To keep single-threaded userspace implementations happy the patch-set
> ensures that by the time fuse_release_common calls fuse_file_put, no
> more in-flight I/O exists. Asynchronous fuse callbacks (like
> fuse_readpages_end) cannot trigger FUSE_RELEASE anymore. Hence, we'll
> never block in contexts other than close().
>
> Thanks,
> Maxim
>
> ---
>
> Maxim Patlasov (5):
> fuse: add close_wait flag to fuse_conn
> fuse: cosmetic rework of fuse_send_readpages
> fuse: wait for end of IO on release
> fuse: enable close_wait feature
> fuse: fix synchronous case of fuse_file_put()
>
>
> fs/fuse/file.c | 82 ++++++++++++++++++++++++++++++++++++++-------
> fs/fuse/fuse_i.h | 3 ++
> fs/fuse/inode.c | 5 ++-
> include/uapi/linux/fuse.h | 7 +++-
> 4 files changed, 82 insertions(+), 15 deletions(-)
>

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