Remove valid_bytes from stat _more ioctls

The idea here was that we'd expand the size of the struct and
valid_bytes would tell the kernel which fields were present in
userspace's struct.  That doesn't combine well with the ioctl convention
of having the size of the type baked into the ioctl number.   We'll
remove this to make the world less surprising.  If we expand the
interface we'd add additional ioctls and types.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/ioctl.c

@@ -546,11 +546,6 @@ static long scoutfs_ioc_stat_more(struct file *file, unsigned long arg)
 	struct scoutfs_inode_info *si = SCOUTFS_I(inode);
 	struct scoutfs_ioctl_stat_more stm;
 
-	if (get_user(stm.valid_bytes, (__u64 __user *)arg))
-		return -EFAULT;
-
-	stm.valid_bytes = min_t(u64, stm.valid_bytes,
-				sizeof(struct scoutfs_ioctl_stat_more));
 	stm.meta_seq = scoutfs_inode_meta_seq(inode);
 	stm.data_seq = scoutfs_inode_data_seq(inode);
 	stm.data_version = scoutfs_inode_data_version(inode);
@@ -558,7 +553,7 @@ static long scoutfs_ioc_stat_more(struct file *file, unsigned long arg)
 	stm.crtime_sec = si->crtime.tv_sec;
 	stm.crtime_nsec = si->crtime.tv_nsec;
 
-	if (copy_to_user((void __user *)arg, &stm, stm.valid_bytes))
+	if (copy_to_user((void __user *)arg, &stm, sizeof(stm)))
 		return -EFAULT;
 
 	return 0;
@@ -879,9 +874,6 @@ static long scoutfs_ioc_statfs_more(struct file *file, unsigned long arg)
 	struct scoutfs_ioctl_statfs_more sfm;
 	int ret;
 
-	if (get_user(sfm.valid_bytes, (__u64 __user *)arg))
-		return -EFAULT;
-
 	super = kzalloc(sizeof(struct scoutfs_super_block), GFP_NOFS);
 	if (!super)
 		return -ENOMEM;
@@ -890,8 +882,6 @@ static long scoutfs_ioc_statfs_more(struct file *file, unsigned long arg)
 	if (ret)
 		goto out;
 
-	sfm.valid_bytes = min_t(u64, sfm.valid_bytes,
-				sizeof(struct scoutfs_ioctl_statfs_more));
 	sfm.fsid = le64_to_cpu(super->hdr.fsid);
 	sfm.rid = sbi->rid;
 	sfm.total_meta_blocks = le64_to_cpu(super->total_meta_blocks);
@@ -902,7 +892,7 @@ static long scoutfs_ioc_statfs_more(struct file *file, unsigned long arg)
 	if (ret)
 		goto out;
 
-	if (copy_to_user((void __user *)arg, &sfm, sfm.valid_bytes))
+	if (copy_to_user((void __user *)arg, &sfm, sizeof(sfm)))
 		ret = -EFAULT;
 	else
 		ret = 0;

kmod/src/ioctl.h

@@ -215,18 +215,8 @@ struct scoutfs_ioctl_stage {
 /*
  * Give the user inode fields that are not otherwise visible.  statx()
  * isn't always available and xattrs are relatively expensive.
- *
- * @valid_bytes stores the number of bytes that are valid in the
- * structure.  The caller sets this to the size of the struct that they
- * understand.  The kernel then fills and copies back the min of the
- * size they and the user caller understand.  The user can tell if a
- * field is set if all of its bytes are within the valid_bytes that the
- * kernel set on return.
- *
- * New fields are only added to the end of the struct.
  */
 struct scoutfs_ioctl_stat_more {
-	__u64 valid_bytes;
 	__u64 meta_seq;
 	__u64 data_seq;
 	__u64 data_version;
@@ -356,21 +346,11 @@ struct scoutfs_ioctl_search_xattrs {
 /*
  * Give the user information about the filesystem.
  *
- * @valid_bytes stores the number of bytes that are valid in the
- * structure.  The caller sets this to the size of the struct that they
- * understand.  The kernel then fills and copies back the min of the
- * size they and the user caller understand.  The user can tell if a
- * field is set if all of its bytes are within the valid_bytes that the
- * kernel set on return.
- *
  * @committed_seq: All seqs up to and including this seq have been
  * committed.  Can be compared with meta_seq and data_seq from inodes in
  * stat_more to discover if changes have been committed to disk.
- *
- * New fields are only added to the end of the struct.
  */
 struct scoutfs_ioctl_statfs_more {
-	__u64 valid_bytes;
 	__u64 fsid;
 	__u64 rid;
 	__u64 committed_seq;

tests/src/stage_tmpfile.c

@@ -113,7 +113,6 @@ int main(int argc, char **argv)
 	}
 
 	// get current data_version after fallocate's size extensions
-	stm.valid_bytes = sizeof(struct scoutfs_ioctl_stat_more);
 	ret = ioctl(dest_fd, SCOUTFS_IOC_STAT_MORE, &stm);
 	if (ret < 0) {
 		perror("stat_more ioctl error");

utils/src/df.c

@@ -48,7 +48,6 @@ static int do_df(struct df_args *args)
 	if (fd < 0)
 		return fd;
 
-	sfm.valid_bytes = sizeof(struct scoutfs_ioctl_statfs_more);
 	ret = ioctl(fd, SCOUTFS_IOC_STATFS_MORE, &sfm);
 	if (ret < 0) {
 		fprintf(stderr, "statfs_more returned %d: error %s (%d)\n",

utils/src/stat.c

@@ -131,12 +131,10 @@ static int do_stat(struct stat_args *args)
 	if (args->is_inode) {
 		cmd = SCOUTFS_IOC_STAT_MORE;
 		fields = inode_fields;
-		st.stm.valid_bytes = sizeof(struct scoutfs_ioctl_stat_more);
 		pr = print_inode_field;
 	} else {
 		cmd = SCOUTFS_IOC_STATFS_MORE;
 		fields = fs_fields;
-		st.sfm.valid_bytes = sizeof(struct scoutfs_ioctl_statfs_more);
 		pr = print_fs_field;
 	}