[PATCH RFC v2 1/6] fs: vfs ioctls for managing project id

[Konstantin Khlebnikov <khlebnikov@yandex-team.ru>]

This patch adds generic vfs interface for project id and
related super-block methods.

Two new ioctls:
int ioctl(fd, FS_IOC_GETPROJECT, unsigned *project);
int ioctl(fd, FS_IOC_SETPROJECT, unsigned *project);

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 Documentation/filesystems/Locking |    4 +++
 Documentation/filesystems/vfs.txt |    8 +++++
 fs/compat_ioctl.c                 |    2 +
 fs/ioctl.c                        |   58 +++++++++++++++++++++++++++++++++++++
 include/linux/fs.h                |    2 +
 include/uapi/linux/fs.h           |    3 ++
 6 files changed, 77 insertions(+)

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index f91926f2f482..7a01e2b606d0 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -126,6 +126,8 @@ prototypes:
 	ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
 	ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
 	int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
+	kprojid_t (*get_project) (struct inode *);
+	int (*set_project) (struct inode *, kprojid_t);
 
 locking rules:
 	All may block [not true, see below]
@@ -147,6 +149,8 @@ show_options:		no		(namespace_sem)
 quota_read:		no		(see below)
 quota_write:		no		(see below)
 bdev_try_to_free_page:	no		(see below)
+get_project		no
+set_project		no		(i_mutex)
 
 ->statfs() has s_umount (shared) when called by ustat(2) (native or
 compat), but that's an accident of bad API; s_umount is used to pin
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 966b22829f3b..aeff3c54021b 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -230,6 +230,8 @@ struct super_operations {
         ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
 	int (*nr_cached_objects)(struct super_block *);
 	void (*free_cached_objects)(struct super_block *, int);
+	kprojid_t (*get_project)(struct inode *);
+	int (*set_project)(struct inode *, kprojid_t);
 };
 
 All methods are called without any locks being held, unless otherwise
@@ -319,6 +321,12 @@ or bottom half).
 	implementations will cause holdoff problems due to large scan batch
 	sizes.
 
+  get_project: called by the ioctl and quota code to get project id of an inode.
+	Method should return INVALID_PROJID if feature isn't supported.
+
+  set_project: called by the ioctl to set project id for an inode.
+	This is called with i_mutex held.
+
 Whoever sets up the inode is responsible for filling in the "i_op" field. This
 is a pointer to a "struct inode_operations" which describes the methods that
 can be performed on individual inodes.
diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index afec6450450f..9a24e4038377 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -889,6 +889,8 @@ COMPATIBLE_IOCTL(FIOASYNC)
 COMPATIBLE_IOCTL(FIONBIO)
 COMPATIBLE_IOCTL(FIONREAD)  /* This is also TIOCINQ */
 COMPATIBLE_IOCTL(FS_IOC_FIEMAP)
+COMPATIBLE_IOCTL(FS_IOC_GETPROJECT)
+COMPATIBLE_IOCTL(FS_IOC_SETPROJECT)
 /* 0x00 */
 COMPATIBLE_IOCTL(FIBMAP)
 COMPATIBLE_IOCTL(FIGETBSZ)
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 5d01d2638ca5..d351576d95c8 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -9,6 +9,7 @@
 #include <linux/capability.h>
 #include <linux/file.h>
 #include <linux/fs.h>
+#include <linux/mount.h>
 #include <linux/security.h>
 #include <linux/export.h>
 #include <linux/uaccess.h>
@@ -545,6 +546,57 @@ static int ioctl_fsthaw(struct file *filp)
 	return thaw_super(sb);
 }
 
+static int ioctl_getproject(struct file *filp, projid_t __user *argp)
+{
+	struct user_namespace *ns = current_user_ns();
+	struct inode *inode = file_inode(filp);
+	struct super_block *sb = inode->i_sb;
+	kprojid_t kprojid;
+	projid_t projid;
+
+	if (!sb->s_op->get_project)
+		return -EOPNOTSUPP;
+	kprojid = sb->s_op->get_project(inode);
+	if (!projid_valid(kprojid))
+		return -EOPNOTSUPP;
+	projid = from_kprojid(ns, kprojid);
+	if (projid == (projid_t)-1)
+		return -EACCES;
+	return put_user(projid, argp);
+}
+
+static int ioctl_setproject(struct file *filp, projid_t __user *argp)
+{
+	struct user_namespace *ns = current_user_ns();
+	struct inode *inode = file_inode(filp);
+	struct super_block *sb = inode->i_sb;
+	kprojid_t kprojid;
+	projid_t projid;
+	int ret;
+
+	if (!sb->s_op->set_project)
+		return -EOPNOTSUPP;
+	if (ns != &init_user_ns)
+		return -EPERM;
+	ret = get_user(projid, argp);
+	if (ret)
+		return ret;
+	kprojid = make_kprojid(ns, projid);
+	if (!projid_valid(kprojid))
+		return -EACCES;
+	ret = mnt_want_write_file(filp);
+	if (ret)
+		return ret;
+	mutex_lock(&inode->i_mutex);
+	if (inode_owner_or_capable(inode))
+		ret = sb->s_op->set_project(inode, kprojid);
+	else
+		ret = -EPERM;
+	mutex_unlock(&inode->i_mutex);
+	mnt_drop_write_file(filp);
+	return ret;
+}
+
 /*
  * When you add any new common ioctls to the switches above and below
  * please update compat_sys_ioctl() too.
@@ -597,6 +649,12 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 	case FS_IOC_FIEMAP:
 		return ioctl_fiemap(filp, arg);
 
+	case FS_IOC_GETPROJECT:
+		return ioctl_getproject(filp, argp);
+
+	case FS_IOC_SETPROJECT:
+		return ioctl_setproject(filp, argp);
+
 	case FIGETBSZ:
 		return put_user(inode->i_sb->s_blocksize, argp);
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b4d71b5e1ff2..42156801739e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1655,6 +1655,8 @@ struct super_operations {
 				  struct shrink_control *);
 	long (*free_cached_objects)(struct super_block *,
 				    struct shrink_control *);
+	kprojid_t (*get_project)(struct inode *);
+	int (*set_project)(struct inode *, kprojid_t);
 };
 
 /*
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 9b964a5920af..144426326e15 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -170,6 +170,9 @@ struct inodes_stat_t {
 #define FS_IOC32_GETVERSION		_IOR('v', 1, int)
 #define FS_IOC32_SETVERSION		_IOW('v', 2, int)
 
+#define FS_IOC_GETPROJECT		_IOR('f', 20, unsigned)
+#define FS_IOC_SETPROJECT		_IOW('f', 21, unsigned)
+
 /*
  * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)
  */