Linux 4.11 compat: iops.getattr and friends

In torvalds/linux@a528d35, there are changes to the getattr family of functions,
struct kstat, and the interface of inode_operations .getattr.

The inode_operations .getattr and simple_getattr() interface changed to:

int (*getattr) (const struct path *, struct dentry *, struct kstat *,
    u32 request_mask, unsigned int query_flags)

The request_mask argument indicates which field(s) the caller intends to use.
Fields the caller has not specified via request_mask may be set in the returned
struct anyway, but their values may be approximate.

The query_flags argument indicates whether the filesystem must update
the attributes from the backing store.

Currently both fields are ignored.  It is possible that getattr-related
functions within zfs could be optimized based on the request_mask.

struct kstat includes new fields:
u32               result_mask;  /* What fields the user got */
u64               attributes;   /* See STATX_ATTR_* flags */
struct timespec   btime;        /* File creation time */

Fields attribute and btime are cleared; the result_mask reflects this.  These
appear to be optional based on simple_getattr() and vfs_getattr() within the
kernel, which take the same approach.

Reviewed-by: Chunwei Chen <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Olaf Faaland <[email protected]>
Closes #5875 

2 files changed, 68 insertions, 0 deletions

diff --git a/config/kernel-inode-getattr.m4 b/config/kernel-inode-getattr.m4
new file mode 100644
index 000000000..f10e0b251
--- /dev/null
+++ b/config/kernel-inode-getattr.m4
@@ -0,0 +1,67 @@
+dnl #
+dnl # Linux 4.11 API
+dnl # See torvalds/linux@a528d35
+dnl #
+AC_DEFUN([ZFS_AC_PATH_KERNEL_IOPS_GETATTR], [
+	AC_MSG_CHECKING([whether iops->getattr() takes a path])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+
+		int test_getattr(
+		    const struct path *p, struct kstat *k,
+		    u32 request_mask, unsigned int query_flags)
+		    { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.getattr = test_getattr,
+		};
+	],[
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_PATH_IOPS_GETATTR, 1,
+		    [iops->getattr() takes a path])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+
+
+dnl #
+dnl # Linux 3.9 - 4.10 API
+dnl #
+AC_DEFUN([ZFS_AC_VFSMOUNT_KERNEL_IOPS_GETATTR], [
+	AC_MSG_CHECKING([whether iops->getattr() takes a vfsmount])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+
+		int test_getattr(
+		    struct vfsmount *mnt, struct dentry *d,
+		    struct kstat *k)
+		    { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.getattr = test_getattr,
+		};
+	],[
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_VFSMOUNT_IOPS_GETATTR, 1,
+		    [iops->getattr() takes a vfsmount])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+
+dnl #
+dnl # The interface of the getattr callback from the inode_operations
+dnl # structure changed.  Also, the interface of the simple_getattr()
+dnl # function provided by the kernel changed.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_INODE_OPERATIONS_GETATTR], [
+	ZFS_AC_PATH_KERNEL_IOPS_GETATTR
+	ZFS_AC_VFSMOUNT_KERNEL_IOPS_GETATTR
+])
diff --git a/config/kernel.m4 b/config/kernel.m4
index 0b50a54e3..25271cedc 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -59,6 +59,7 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL_INODE_OPERATIONS_CHECK_ACL_WITH_FLAGS
 	ZFS_AC_KERNEL_INODE_OPERATIONS_GET_ACL
 	ZFS_AC_KERNEL_INODE_OPERATIONS_SET_ACL
+	ZFS_AC_KERNEL_INODE_OPERATIONS_GETATTR
 	ZFS_AC_KERNEL_INODE_SET_FLAGS
 	ZFS_AC_KERNEL_GET_ACL_HANDLE_CACHE
 	ZFS_AC_KERNEL_SHOW_OPTIONS