On Thu, Feb 03, 2022 at 06:56:58PM +0000, Dr. David Alan Gilbert wrote:
> * Vivek Goyal (vgo...@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 <vgo...@redhat.com>
> > ---
> > 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.
Good catch. I did not think about it.
> 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.
Will use "endof" macro.
Thanks
Vivek
>
> 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 / dgilb...@redhat.com / Manchester, UK
>
