Implement File Attribute Support

We add support for lsattr and chattr. Only attributes common to both
Solaris and Linux are supported. These are 'a', 'd' and 'i'. File
attributes exclusive to Solaris are present in the ZFS code, but cannot
be accessed or modified through this method. That was the case prior to
this patch.

This commit removes the ZFS_IOC_GETFLAGS and ZFS_IOC_SETFLAGS macros in
recognition that this is not equivalent to the Solaris operation. The
resolution of issue openzfs#229 should implement something
equivalent that will permit access and modification of Solaris-specific
attributes.

This resolves a regression caused by
88c2839 that broke python's
xattr.list(). This broke Gentoo Portage's FEATURES=xattr, which depended
on this.

https://bugs.gentoo.org/show_bug.cgi?id=483516
Issue openzfs#1691

Original-patch-by: Brian Behlendorf <[email protected]>
Signed-off-by: Richard Yao <[email protected]>

config/kernel-is_owner_or_cap.m4

@@ -0,0 +1,30 @@
+dnl #
+dnl # 2.6.39 API change
+dnl # is_owner_or_cap() was renamed to inode_owner_or_capable().
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE], [
+	AC_MSG_CHECKING([whether inode_owner_or_capable() exists])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+	],[
+		struct inode *ip = NULL;
+		inode_owner_or_capable(ip);
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE, 1, [inode_owner_or_capable() exists])
+	],[
+		AC_MSG_RESULT(no)
+		AC_MSG_CHECKING([whether is_owner_or_cap() exists])
+		ZFS_LINUX_TRY_COMPILE([
+			#include <linux/fs.h>
+		],[
+			struct inode *ip = NULL;
+			is_owner_or_cap(ip);
+		],[
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_IS_OWNER_OR_CAP, 1, [is_owner_or_cap() exists])
+		],[
+			AC_MSG_ERROR(no; file a bug report with ZFSOnLinux)
+		])
+	])
+])

config/kernel.m4

@@ -94,6 +94,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL_5ARG_SGET
 	ZFS_AC_KERNEL_LSEEK_EXECUTE
 	ZFS_AC_KERNEL_VFS_ITERATE
+	ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE
 
 	AS_IF([test "$LINUX_OBJ" != "$LINUX"], [
 		KERNELMAKE_PARAMS="$KERNELMAKE_PARAMS O=$LINUX_OBJ"

include/linux/vfs_compat.h

@@ -152,9 +152,6 @@ typedef	int		zpl_umode_t;
 #define	zpl_sget(type, cmp, set, fl, mtd)	sget(type, cmp, set, mtd)
 #endif /* HAVE_5ARG_SGET */
 
-#define	ZFS_IOC_GETFLAGS	FS_IOC_GETFLAGS
-#define	ZFS_IOC_SETFLAGS	FS_IOC_SETFLAGS
-
 #if defined(SEEK_HOLE) && defined(SEEK_DATA) && !defined(HAVE_LSEEK_EXECUTE)
 static inline loff_t
 lseek_execute(

module/zfs/zpl_file.c

@@ -520,13 +520,103 @@ zpl_fallocate(struct file *filp, int mode, loff_t offset, loff_t len)
 }
 #endif /* HAVE_FILE_FALLOCATE */
 
+/*
+ * Map zfs file z_pflags (xvattr_t) to linux file attributes. Only file
+ * attributes common to both Linux and Solaris are mapped.
+ */
+static int
+zpl_ioctl_getflags(struct file *filp, void __user *arg)
+{
+	struct inode *ip = filp->f_dentry->d_inode;
+	unsigned int ioctl_flags = 0;
+	uint64_t zfs_flags = ITOZ(ip)->z_pflags;
+	int error;
+
+	if (zfs_flags & ZFS_IMMUTABLE)
+		ioctl_flags |= FS_IMMUTABLE_FL;
+
+	if (zfs_flags & ZFS_APPENDONLY)
+		ioctl_flags |= FS_APPEND_FL;
+
+	if (zfs_flags & ZFS_NODUMP)
+		ioctl_flags |= FS_NODUMP_FL;
+
+	ioctl_flags &= FS_FL_USER_VISIBLE;
+
+	error = copy_to_user(arg, &ioctl_flags, sizeof(ioctl_flags));
+
+	return (error);
+}
+
+static int
+zpl_ioctl_setflags(struct file *filp, void __user *arg)
+{
+	struct inode *ip = filp->f_dentry->d_inode;
+	znode_t *zp = ITOZ(ip);
+	unsigned int ioctl_flags;
+	uint64_t zfs_flags, old_zfs_flags;
+	cred_t *cr = CRED();
+	xvattr_t xva;
+	int error;
+
+	if (copy_from_user(&ioctl_flags, arg, sizeof(ioctl_flags)))
+		return (-EFAULT);
+
+	if ((ioctl_flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL)))
+		return (-EOPNOTSUPP);
+
+	if ((ioctl_flags & ~(FS_FL_USER_MODIFIABLE)))
+		return (-EACCES);
+
+	if ((ioctl_flags & (FS_IMMUTABLE_FL | FS_APPEND_FL)
+		&& !capable(CAP_LINUX_IMMUTABLE)))
+		return (-EACCES);
+
+#ifdef HAVE_INODE_OWNER_OR_CAPABLE
+	if (!inode_owner_or_capable(ip))
+#else
+	if (!is_owner_or_cap(ip))
+#endif
+		return (-EACCES);
+
+	xva_init(&xva);
+	zfs_flags = old_zfs_flags = ITOZ(ip)->z_pflags;
+
+	if (ioctl_flags & FS_IMMUTABLE_FL)
+		zfs_flags |= ZFS_IMMUTABLE;
+	else
+		zfs_flags &= ~ZFS_IMMUTABLE;
+
+	if (ioctl_flags & FS_APPEND_FL)
+		zfs_flags |= ZFS_APPENDONLY;
+	else
+		zfs_flags &= ~ZFS_APPENDONLY;
+
+	if (ioctl_flags & FS_NODUMP_FL)
+		zfs_flags |= ZFS_NODUMP;
+	else
+		zfs_flags &= ~ZFS_NODUMP;
+
+	zp->z_pflags = zfs_flags;
+
+	crhold(cr);
+	error = -zfs_setattr(ip, (vattr_t *)&xva, 0, cr);
+	crfree(cr);
+
+	if (error)
+		zp->z_pflags = old_zfs_flags;
+
+	return (error);
+}
+
 static long
 zpl_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	switch (cmd) {
-	case ZFS_IOC_GETFLAGS:
-	case ZFS_IOC_SETFLAGS:
-		return (-EOPNOTSUPP);
+	case FS_IOC_GETFLAGS:
+		return zpl_ioctl_getflags(filp, (void *)arg);
+	case FS_IOC_SETFLAGS:
+		return zpl_ioctl_setflags(filp, (void *)arg);
 	default:
 		return (-ENOTTY);
 	}