[PATCH v2 1/2] fuse: Add support for FUSE_SETXATTR_V2

[Vivek Goyal]

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@xxxxxxxxxx>
---
 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;
 	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