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Linux 5.14 compat: explicity assign set_page_dirty 

Kernel 5.14 introduced a change where set_page_dirty of
struct address_space_operations is no longer implicitly set to
__set_page_dirty_buffers(), which ended up resulting in a NULL
pointer deref in the kernel when it is attempted to be called.
This change sets .set_page_dirty in the structure to
__set_page_dirty_nobuffers(), which was introduced with the
related patch set. The breaking change was introduce in commit
0af573780b0b13fceb7fabd49dc1b073cee9a507 to torvalds/linux.git.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes #12427
This commit is contained in:
Coleman Kane 2021-07-26 13:55:55 -04:00 committed by Tony Hutter
parent 744cdfd93b
commit 6b9d0eda75
3 changed files with 42 additions and 0 deletions
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34
config/kernel-vfs-set_page_dirty.m4 Normal file
View File

@ -0,0 +1,34 @@
dnl #
dnl # Linux 5.14 adds a change to require set_page_dirty to be manually
dnl # wired up in struct address_space_operations. Determine if this needs
dnl # to be done. This patch set also introduced __set_page_dirty_nobuffers
dnl # declaration in linux/pagemap.h, so these tests look for the presence
dnl # of that function to tell the compiler to assign set_page_dirty in
dnl # module/os/linux/zfs/zpl_file.c
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_VFS_SET_PAGE_DIRTY_NOBUFFERS], [
ZFS_LINUX_TEST_SRC([vfs_has_set_page_dirty_nobuffers], [
#include <linux/pagemap.h>
#include <linux/fs.h>
static const struct address_space_operations
aops __attribute__ ((unused)) = {
.set_page_dirty = __set_page_dirty_nobuffers,
};
],[])
])
AC_DEFUN([ZFS_AC_KERNEL_VFS_SET_PAGE_DIRTY_NOBUFFERS], [
dnl #
dnl # Linux 5.14 change requires set_page_dirty() to be assigned
dnl # in address_space_operations()
dnl #
AC_MSG_CHECKING([__set_page_dirty_nobuffers exists])
ZFS_LINUX_TEST_RESULT([vfs_has_set_page_dirty_nobuffers], [
AC_MSG_RESULT([yes])
AC_DEFINE(HAVE_VFS_SET_PAGE_DIRTY_NOBUFFERS, 1,
[__set_page_dirty_nobuffers exists])
],[
AC_MSG_RESULT([no])
])
])

2
config/kernel.m4
View File

@ -131,6 +131,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
ZFS_AC_KERNEL_SRC_SIGNAL_STOP
ZFS_AC_KERNEL_SRC_SIGINFO
ZFS_AC_KERNEL_SRC_SET_SPECIAL_STATE
ZFS_AC_KERNEL_SRC_VFS_SET_PAGE_DIRTY_NOBUFFERS
AC_MSG_CHECKING([for available kernel interfaces])
ZFS_LINUX_TEST_COMPILE_ALL([kabi])
@ -235,6 +236,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
ZFS_AC_KERNEL_SIGNAL_STOP
ZFS_AC_KERNEL_SIGINFO
ZFS_AC_KERNEL_SET_SPECIAL_STATE
ZFS_AC_KERNEL_VFS_SET_PAGE_DIRTY_NOBUFFERS
])
dnl #

6
module/os/linux/zfs/zpl_file.c
View File

@ -33,6 +33,9 @@
#include <sys/zfs_vfsops.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_project.h>
#ifdef HAVE_VFS_SET_PAGE_DIRTY_NOBUFFERS
#include <linux/pagemap.h>
#endif
/*
* When using fallocate(2) to preallocate space, inflate the requested
@ -1007,6 +1010,9 @@ const struct address_space_operations zpl_address_space_operations = {
.writepage = zpl_writepage,
.writepages = zpl_writepages,
.direct_IO = zpl_direct_IO,
#ifdef HAVE_VFS_SET_PAGE_DIRTY_NOBUFFERS
.set_page_dirty = __set_page_dirty_nobuffers,
#endif
};
const struct file_operations zpl_file_operations = {