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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id m11sm7103993wmi.16.2022.02.03.10.57.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Feb 2022 10:57:00 -0800 (PST) Date: Thu, 3 Feb 2022 18:56:58 +0000 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: [PATCH v5 3/9] virtiofsd: Parse extended "struct fuse_init_in" Message-ID: References: <20220202193935.268777-1-vgoyal@redhat.com> <20220202193935.268777-4-vgoyal@redhat.com> MIME-Version: 1.0 In-Reply-To: <20220202193935.268777-4-vgoyal@redhat.com> User-Agent: Mutt/2.1.5 (2021-12-30) Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.086, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, mszeredi@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Vivek Goyal (vgoyal@redhat.com) wrote: > Add some code to parse extended "struct fuse_init_in". And use a local > variable "flag" to represent 64 bit flags. This will make it easier > to add more features without having to worry about two 32bit flags (->flags > and ->flags2) in "fuse_struct_in". > > Signed-off-by: Vivek Goyal > --- > tools/virtiofsd/fuse_lowlevel.c | 62 +++++++++++++++++++++------------ > 1 file changed, 40 insertions(+), 22 deletions(-) > > diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c > index ce29a70253..1f10dcc75b 100644 > --- a/tools/virtiofsd/fuse_lowlevel.c > +++ b/tools/virtiofsd/fuse_lowlevel.c > @@ -1881,11 +1881,15 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, > { > size_t compat_size = offsetof(struct fuse_init_in, max_readahead); > size_t compat2_size = offsetof(struct fuse_init_in, flags) + sizeof(uint32_t); > + /* Fuse structure extended with minor version 36 */ > + size_t compat3_size = offsetof(struct fuse_init_in, unused) + > + (11 * sizeof(uint32_t)); Hmm that's actually quite difficult; what we have at the moment is: struct fuse_init_in { uint32_t major; uint32_t minor; uint32_t max_readahead; uint32_t flags; uint32_t flags2; uint32_t unused[11]; }; so imagine someone comes along and changes that to: struct fuse_init_in { uint32_t major; uint32_t minor; uint32_t max_readahead; uint32_t flags; uint32_t flags2; uint32_t flags3; uint32_t unused[10]; }; Then this code will break (oddly!), where the old code that didn't reference the unusued field wouldn't. It looks like qemu defines an 'endof' macro, so I think you can do: size_t compat3_size = endof(struct fuse_init_in, unused); I think that should work as long as people nibble away at unused from the top. Dave > struct fuse_init_in *arg; > struct fuse_init_out outarg; > struct fuse_session *se = req->se; > size_t bufsize = se->bufsize; > size_t outargsize = sizeof(outarg); > + uint64_t flags = 0; > > (void)nodeid; > > @@ -1902,11 +1906,25 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, > fuse_reply_err(req, EINVAL); > return; > } > + flags |= arg->flags; > + } > + > + /* > + * fuse_init_in was extended again with minor version 36. Just read > + * current known size of fuse_init so that future extension and > + * header rebase does not cause breakage. > + */ > + if (sizeof(*arg) > compat2_size && (arg->flags & FUSE_INIT_EXT)) { > + if (!fuse_mbuf_iter_advance(iter, compat3_size - compat2_size)) { > + fuse_reply_err(req, EINVAL); > + return; > + } > + flags |= (uint64_t) arg->flags2 << 32; > } > > fuse_log(FUSE_LOG_DEBUG, "INIT: %u.%u\n", arg->major, arg->minor); > if (arg->major == 7 && arg->minor >= 6) { > - fuse_log(FUSE_LOG_DEBUG, "flags=0x%08x\n", arg->flags); > + fuse_log(FUSE_LOG_DEBUG, "flags=0x%016llx\n", flags); > fuse_log(FUSE_LOG_DEBUG, "max_readahead=0x%08x\n", arg->max_readahead); > } > se->conn.proto_major = arg->major; > @@ -1934,68 +1952,68 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, > if (arg->max_readahead < se->conn.max_readahead) { > se->conn.max_readahead = arg->max_readahead; > } > - if (arg->flags & FUSE_ASYNC_READ) { > + if (flags & FUSE_ASYNC_READ) { > se->conn.capable |= FUSE_CAP_ASYNC_READ; > } > - if (arg->flags & FUSE_POSIX_LOCKS) { > + if (flags & FUSE_POSIX_LOCKS) { > se->conn.capable |= FUSE_CAP_POSIX_LOCKS; > } > - if (arg->flags & FUSE_ATOMIC_O_TRUNC) { > + if (flags & FUSE_ATOMIC_O_TRUNC) { > se->conn.capable |= FUSE_CAP_ATOMIC_O_TRUNC; > } > - if (arg->flags & FUSE_EXPORT_SUPPORT) { > + if (flags & FUSE_EXPORT_SUPPORT) { > se->conn.capable |= FUSE_CAP_EXPORT_SUPPORT; > } > - if (arg->flags & FUSE_DONT_MASK) { > + if (flags & FUSE_DONT_MASK) { > se->conn.capable |= FUSE_CAP_DONT_MASK; > } > - if (arg->flags & FUSE_FLOCK_LOCKS) { > + if (flags & FUSE_FLOCK_LOCKS) { > se->conn.capable |= FUSE_CAP_FLOCK_LOCKS; > } > - if (arg->flags & FUSE_AUTO_INVAL_DATA) { > + if (flags & FUSE_AUTO_INVAL_DATA) { > se->conn.capable |= FUSE_CAP_AUTO_INVAL_DATA; > } > - if (arg->flags & FUSE_DO_READDIRPLUS) { > + if (flags & FUSE_DO_READDIRPLUS) { > se->conn.capable |= FUSE_CAP_READDIRPLUS; > } > - if (arg->flags & FUSE_READDIRPLUS_AUTO) { > + if (flags & FUSE_READDIRPLUS_AUTO) { > se->conn.capable |= FUSE_CAP_READDIRPLUS_AUTO; > } > - if (arg->flags & FUSE_ASYNC_DIO) { > + if (flags & FUSE_ASYNC_DIO) { > se->conn.capable |= FUSE_CAP_ASYNC_DIO; > } > - if (arg->flags & FUSE_WRITEBACK_CACHE) { > + if (flags & FUSE_WRITEBACK_CACHE) { > se->conn.capable |= FUSE_CAP_WRITEBACK_CACHE; > } > - if (arg->flags & FUSE_NO_OPEN_SUPPORT) { > + if (flags & FUSE_NO_OPEN_SUPPORT) { > se->conn.capable |= FUSE_CAP_NO_OPEN_SUPPORT; > } > - if (arg->flags & FUSE_PARALLEL_DIROPS) { > + if (flags & FUSE_PARALLEL_DIROPS) { > se->conn.capable |= FUSE_CAP_PARALLEL_DIROPS; > } > - if (arg->flags & FUSE_POSIX_ACL) { > + if (flags & FUSE_POSIX_ACL) { > se->conn.capable |= FUSE_CAP_POSIX_ACL; > } > - if (arg->flags & FUSE_HANDLE_KILLPRIV) { > + if (flags & FUSE_HANDLE_KILLPRIV) { > se->conn.capable |= FUSE_CAP_HANDLE_KILLPRIV; > } > - if (arg->flags & FUSE_NO_OPENDIR_SUPPORT) { > + if (flags & FUSE_NO_OPENDIR_SUPPORT) { > se->conn.capable |= FUSE_CAP_NO_OPENDIR_SUPPORT; > } > - if (!(arg->flags & FUSE_MAX_PAGES)) { > + if (!(flags & FUSE_MAX_PAGES)) { > size_t max_bufsize = FUSE_DEFAULT_MAX_PAGES_PER_REQ * getpagesize() + > FUSE_BUFFER_HEADER_SIZE; > if (bufsize > max_bufsize) { > bufsize = max_bufsize; > } > } > - if (arg->flags & FUSE_SUBMOUNTS) { > + if (flags & FUSE_SUBMOUNTS) { > se->conn.capable |= FUSE_CAP_SUBMOUNTS; > } > - if (arg->flags & FUSE_HANDLE_KILLPRIV_V2) { > + if (flags & FUSE_HANDLE_KILLPRIV_V2) { > se->conn.capable |= FUSE_CAP_HANDLE_KILLPRIV_V2; > } > - if (arg->flags & FUSE_SETXATTR_EXT) { > + if (flags & FUSE_SETXATTR_EXT) { > se->conn.capable |= FUSE_CAP_SETXATTR_EXT; > } > #ifdef HAVE_SPLICE > @@ -2063,7 +2081,7 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, > if (se->conn.max_write < bufsize - FUSE_BUFFER_HEADER_SIZE) { > se->bufsize = se->conn.max_write + FUSE_BUFFER_HEADER_SIZE; > } > - if (arg->flags & FUSE_MAX_PAGES) { > + if (flags & FUSE_MAX_PAGES) { > outarg.flags |= FUSE_MAX_PAGES; > outarg.max_pages = (se->conn.max_write - 1) / getpagesize() + 1; > } > -- > 2.34.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK