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Date: Mon, 29 Mar 2021 14:24:08 -0400
From: Vivek Goyal <vgoyal@...hat.com>
To: Luis Henriques <lhenriques@...e.de>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
virtio-fs@...hat.com, miklos@...redi.hu, dgilbert@...hat.com,
seth.forshee@...onical.com
Subject: Re: [PATCH v2 1/2] fuse: Add support for FUSE_SETXATTR_V2
On Mon, Mar 29, 2021 at 03:54:03PM +0100, Luis Henriques wrote:
> On Thu, Mar 25, 2021 at 11:18:22AM -0400, Vivek Goyal wrote:
> > Fuse client needs to send additional information to file server when
> > it calls SETXATTR(system.posix_acl_access). Right now there is no extra
> > space in fuse_setxattr_in. So introduce a v2 of the structure which has
> > more space in it and can be used to send extra flags.
> >
> > "struct fuse_setxattr_in_v2" is only used if file server opts-in for it using
> > flag FUSE_SETXATTR_V2 during feature negotiations.
> >
> > Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
> > ---
> > fs/fuse/acl.c | 2 +-
> > fs/fuse/fuse_i.h | 5 ++++-
> > fs/fuse/inode.c | 4 +++-
> > fs/fuse/xattr.c | 21 +++++++++++++++------
> > include/uapi/linux/fuse.h | 10 ++++++++++
> > 5 files changed, 33 insertions(+), 9 deletions(-)
> >
> > diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
> > index e9c0f916349d..d31260a139d4 100644
> > --- a/fs/fuse/acl.c
> > +++ b/fs/fuse/acl.c
> > @@ -94,7 +94,7 @@ int fuse_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
> > return ret;
> > }
> >
> > - ret = fuse_setxattr(inode, name, value, size, 0);
> > + ret = fuse_setxattr(inode, name, value, size, 0, 0);
> > kfree(value);
> > } else {
> > ret = fuse_removexattr(inode, name);
> > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > index 63d97a15ffde..d00bf0b9a38c 100644
> > --- a/fs/fuse/fuse_i.h
> > +++ b/fs/fuse/fuse_i.h
> > @@ -668,6 +668,9 @@ struct fuse_conn {
> > /** Is setxattr not implemented by fs? */
> > unsigned no_setxattr:1;
> >
> > + /** Does file server support setxattr_v2 */
> > + unsigned setxattr_v2:1;
> > +
> > /** Is getxattr not implemented by fs? */
> > unsigned no_getxattr:1;
> >
> > @@ -1170,7 +1173,7 @@ void fuse_unlock_inode(struct inode *inode, bool locked);
> > bool fuse_lock_inode(struct inode *inode);
> >
> > int fuse_setxattr(struct inode *inode, const char *name, const void *value,
> > - size_t size, int flags);
> > + size_t size, int flags, unsigned extra_flags);
> > ssize_t fuse_getxattr(struct inode *inode, const char *name, void *value,
> > size_t size);
> > ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size);
> > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > index b0e18b470e91..1c726df13f80 100644
> > --- a/fs/fuse/inode.c
> > +++ b/fs/fuse/inode.c
> > @@ -1052,6 +1052,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
> > fc->handle_killpriv_v2 = 1;
> > fm->sb->s_flags |= SB_NOSEC;
> > }
> > + if (arg->flags & FUSE_SETXATTR_V2)
> > + fc->setxattr_v2 = 1;
> > } else {
> > ra_pages = fc->max_read / PAGE_SIZE;
> > fc->no_lock = 1;
> > @@ -1095,7 +1097,7 @@ void fuse_send_init(struct fuse_mount *fm)
> > FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |
> > FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS |
> > FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA |
> > - FUSE_HANDLE_KILLPRIV_V2;
> > + FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_V2;
> > #ifdef CONFIG_FUSE_DAX
> > if (fm->fc->dax)
> > ia->in.flags |= FUSE_MAP_ALIGNMENT;
> > diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
> > index 1a7d7ace54e1..f2aae72653dc 100644
> > --- a/fs/fuse/xattr.c
> > +++ b/fs/fuse/xattr.c
> > @@ -12,24 +12,33 @@
> > #include <linux/posix_acl_xattr.h>
> >
> > int fuse_setxattr(struct inode *inode, const char *name, const void *value,
> > - size_t size, int flags)
> > + size_t size, int flags, unsigned extra_flags)
> > {
> > struct fuse_mount *fm = get_fuse_mount(inode);
> > FUSE_ARGS(args);
> > struct fuse_setxattr_in inarg;
> > + struct fuse_setxattr_in_v2 inarg_v2;
> > + bool setxattr_v2 = fm->fc->setxattr_v2;
> > int err;
> >
> > if (fm->fc->no_setxattr)
> > return -EOPNOTSUPP;
> >
> > memset(&inarg, 0, sizeof(inarg));
> > - inarg.size = size;
> > - inarg.flags = flags;
> > + memset(&inarg_v2, 0, sizeof(inarg_v2));
> > + if (setxattr_v2) {
> > + inarg_v2.size = size;
> > + inarg_v2.flags = flags;
> > + inarg_v2.setxattr_flags = extra_flags;
> > + } else {
> > + inarg.size = size;
> > + inarg.flags = flags;
> > + }
> > args.opcode = FUSE_SETXATTR;
> > args.nodeid = get_node_id(inode);
> > args.in_numargs = 3;
> > - args.in_args[0].size = sizeof(inarg);
> > - args.in_args[0].value = &inarg;
> > + args.in_args[0].size = setxattr_v2 ? sizeof(inarg_v2) : sizeof(inarg);
> > + args.in_args[0].value = setxattr_v2 ? &inarg_v2 : (void *)&inarg;
>
> And yet another minor:
>
> It's a bit awkward to have to cast '&inarg' to 'void *' just because
> you're using the ternary operator. Why not use an 'if' statement instead
> for initializing .size and .value?
Yes, I had to use (void *), otherwise compiler was complaining about
returning different types of pointers. Interesting that compiler
expects to return same type of pointer.
I think I am fine with this as well as adding explicit if statement. I
guess just a matter of taste.
Miklos, what do you think? If you also prefer if statement instead,
I will make changes and post again.
Vivek
>
> Cheers,
> --
> Luís
>
> > args.in_args[1].size = strlen(name) + 1;
> > args.in_args[1].value = name;
> > args.in_args[2].size = size;
> > @@ -199,7 +208,7 @@ static int fuse_xattr_set(const struct xattr_handler *handler,
> > if (!value)
> > return fuse_removexattr(inode, name);
> >
> > - return fuse_setxattr(inode, name, value, size, flags);
> > + return fuse_setxattr(inode, name, value, size, flags, 0);
> > }
> >
> > static bool no_xattr_list(struct dentry *dentry)
> > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> > index 54442612c48b..1bb555c1c117 100644
> > --- a/include/uapi/linux/fuse.h
> > +++ b/include/uapi/linux/fuse.h
> > @@ -179,6 +179,7 @@
> > * 7.33
> > * - add FUSE_HANDLE_KILLPRIV_V2, FUSE_WRITE_KILL_SUIDGID, FATTR_KILL_SUIDGID
> > * - add FUSE_OPEN_KILL_SUIDGID
> > + * - add FUSE_SETXATTR_V2
> > */
> >
> > #ifndef _LINUX_FUSE_H
> > @@ -330,6 +331,7 @@ struct fuse_file_lock {
> > * does not have CAP_FSETID. Additionally upon
> > * write/truncate sgid is killed only if file has group
> > * execute permission. (Same as Linux VFS behavior).
> > + * FUSE_SETXATTR_V2: Does file server support V2 of struct fuse_setxattr_in
> > */
> > #define FUSE_ASYNC_READ (1 << 0)
> > #define FUSE_POSIX_LOCKS (1 << 1)
> > @@ -360,6 +362,7 @@ struct fuse_file_lock {
> > #define FUSE_MAP_ALIGNMENT (1 << 26)
> > #define FUSE_SUBMOUNTS (1 << 27)
> > #define FUSE_HANDLE_KILLPRIV_V2 (1 << 28)
> > +#define FUSE_SETXATTR_V2 (1 << 29)
> >
> > /**
> > * CUSE INIT request/reply flags
> > @@ -686,6 +689,13 @@ struct fuse_setxattr_in {
> > uint32_t flags;
> > };
> >
> > +struct fuse_setxattr_in_v2 {
> > + uint32_t size;
> > + uint32_t flags;
> > + uint32_t setxattr_flags;
> > + uint32_t padding;
> > +};
> > +
> > struct fuse_getxattr_in {
> > uint32_t size;
> > uint32_t padding;
> > --
> > 2.25.4
> >
>
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