• Anand Avati's avatar
    fuse: O_DIRECT support for files · 4273b793
    Anand Avati authored
    Implement ->direct_IO() method in aops. The ->direct_IO() method combines
    the existing fuse_direct_read/fuse_direct_write methods to implement
    O_DIRECT functionality.
    Reaching ->direct_IO() in the read path via generic_file_aio_read ensures
    proper synchronization with page cache with its existing framework.
    Reaching ->direct_IO() in the write path via fuse_file_aio_write is made
    to come via generic_file_direct_write() which makes it play nice with
    the page cache w.r.t other mmap pages etc.
    On files marked 'direct_io' by the filesystem server, IO always follows
    the fuse_direct_read/write path. There is no effect of fcntl(O_DIRECT)
    and it always succeeds.
    On files not marked with 'direct_io' by the filesystem server, the IO
    path depends on O_DIRECT flag by the application. This can be passed
    at the time of open() as well as via fcntl().
    Note that asynchronous O_DIRECT iocb jobs are completed synchronously
    always (this has been the case with FUSE even before this patch)
    Signed-off-by: default avatarAnand Avati <avati@redhat.com>
    Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
    Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>