[RFC PATCH] fs: obtain the inode generation number from vfs directly

[Hongbo Li]

Many mainstream file systems already support the GETVERSION ioctl,
and their implementations are completely the same, essentially
just obtain the value of i_generation. We think this ioctl can be
implemented at the VFS layer, so the file systems do not need to
implement it individually.

Signed-off-by: Hongbo Li <lihongbo22 at huawei.com>
---
 fs/ioctl.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 64776891120c..dff887ec52c4 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -878,6 +878,9 @@ static int do_vfs_ioctl(struct file *filp, unsigned int fd,
 	case FS_IOC_GETFSUUID:
 		return ioctl_getfsuuid(filp, argp);
 
+	case FS_IOC_GETVERSION:
+		return put_user(inode->i_generation, (int __user *)argp);
+
 	case FS_IOC_GETFSSYSFSPATH:
 		return ioctl_get_fs_sysfs_path(filp, argp);
 
@@ -992,6 +995,9 @@ COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
 		cmd = (cmd == FS_IOC32_GETFLAGS) ?
 			FS_IOC_GETFLAGS : FS_IOC_SETFLAGS;
 		fallthrough;
+	case FS_IOC32_GETVERSION:
+		cmd = FS_IOC_GETVERSION;
+		fallthrough;
 	/*
 	 * everything else in do_vfs_ioctl() takes either a compatible
 	 * pointer argument or no argument -- call it with a modified
-- 
2.34.1