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Linux 5.12 update: bio_max_segs() replaces BIO_MAX_PAGES 

The BIO_MAX_PAGES macro is being retired in favor of a bio_max_segs()
function that implements the typical MIN(x,y) logic used throughout the
kernel for bounding the allocation, and also the new implementation is
intended to be signed-safe (which the former was not).

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes #11765
(cherry picked from commit ffd6978ef5)
Signed-off-by: Jonathon Fernyhough <jonathon@m2x.dev>
This commit is contained in:
Coleman Kane 2021-03-20 01:33:42 -04:00 committed by Tony Hutter
parent 91d5ac85c0
commit 5722dce473
3 changed files with 30 additions and 0 deletions
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23
config/kernel-bio_max_segs.m4 Normal file
View File

@ -0,0 +1,23 @@
dnl #
dnl # 5.12 API change removes BIO_MAX_PAGES in favor of bio_max_segs()
dnl # which will handle the logic of setting the upper-bound to a
dnl # BIO_MAX_PAGES, internally.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_MAX_SEGS], [
ZFS_LINUX_TEST_SRC([bio_max_segs], [
#include <linux/bio.h>
],[
bio_max_segs(1);
])
])
AC_DEFUN([ZFS_AC_KERNEL_BIO_MAX_SEGS], [
AC_MSG_CHECKING([whether bio_max_segs() exists])
ZFS_LINUX_TEST_RESULT([bio_max_segs], [
AC_MSG_RESULT(yes)
AC_DEFINE([HAVE_BIO_MAX_SEGS], 1, [bio_max_segs() is implemented])
],[
AC_MSG_RESULT(no)
])
])

2
config/kernel.m4
View File

@ -127,6 +127,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS
ZFS_AC_KERNEL_SRC_MKNOD
ZFS_AC_KERNEL_SRC_SYMLINK
ZFS_AC_KERNEL_SRC_BIO_MAX_SEGS
AC_MSG_CHECKING([for available kernel interfaces])
ZFS_LINUX_TEST_COMPILE_ALL([kabi])
@ -227,6 +228,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS
ZFS_AC_KERNEL_MKNOD
ZFS_AC_KERNEL_SYMLINK
ZFS_AC_KERNEL_BIO_MAX_SEGS
])
dnl #

5
module/os/linux/zfs/vdev_disk.c
View File

@ -593,9 +593,14 @@ retry:
}
/* bio_alloc() with __GFP_WAIT never returns NULL */
#ifdef HAVE_BIO_MAX_SEGS
dr->dr_bio[i] = bio_alloc(GFP_NOIO, bio_max_segs(
abd_nr_pages_off(zio->io_abd, bio_size, abd_offset)));
#else
dr->dr_bio[i] = bio_alloc(GFP_NOIO,
MIN(abd_nr_pages_off(zio->io_abd, bio_size, abd_offset),
BIO_MAX_PAGES));
#endif
if (unlikely(dr->dr_bio[i] == NULL)) {
vdev_disk_dio_free(dr);
return (SET_ERROR(ENOMEM));