Comment 25 for bug 2056461

Considering the (changed) source-code of fs/9p/vfs_file.c::v9fs_file_read_iter() in commit 80105ed2fd2715fb09a8fdb0655a8bdc86c120db.

Prior to the commit there was a code path specifically for O_NONBLOCK (as well as for p9L_DIRECT). Now there is only a code-path for P9L_DIRECT.

kernel.36.log shows that within this function the p9L_DIRECT path is taken since there is no debug message from the final debug message:

       if (fid->mode & P9L_DIRECT)
               return netfs_unbuffered_read_iter(iocb, to);

       p9_debug(P9_DEBUG_VFS, "(cached)\n");
       return netfs_file_read_iter(iocb, to);
}

I'm not familiar enough with the netfs layer to understand if O_NONBLOCK is being handled (correctly) there - if special handling is indeed required?