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136 lines
4.4 KiB
136 lines
4.4 KiB
From 2fcab8795c7c493845bfa277d44bc443802000b8 Mon Sep 17 00:00:00 2001
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From: Brian Behlendorf <behlendorf1@llnl.gov>
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Date: Fri, 28 Feb 2020 08:58:39 -0800
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Subject: [PATCH] Linux 5.5 compat: blkg_tryget()
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Commit https://github.com/torvalds/linux/commit/9e8d42a0f accidentally
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converted the static inline function blkg_tryget() to GPL-only for
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kernels built with CONFIG_PREEMPT_RCU=y and CONFIG_BLK_CGROUP=y.
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Resolve the build issue by providing our own equivalent functionality
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when needed which uses rcu_read_lock_sched() internally as before.
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Reviewed-by: Tony Hutter <hutter2@llnl.gov>
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Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
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Closes #9745
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Closes #10072
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---
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config/kernel-blkg-tryget.m4 | 37 ++++++++++++++++++++++++++++++++++++
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config/kernel.m4 | 2 ++
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module/zfs/vdev_disk.c | 32 ++++++++++++++++++++++++++++++-
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3 files changed, 70 insertions(+), 1 deletion(-)
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create mode 100644 config/kernel-blkg-tryget.m4
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diff --git a/config/kernel-blkg-tryget.m4 b/config/kernel-blkg-tryget.m4
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new file mode 100644
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index 00000000000..fb831ca3b3e
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--- /dev/null
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+++ b/config/kernel-blkg-tryget.m4
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@@ -0,0 +1,37 @@
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+dnl #
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+dnl # Linux 5.5 API,
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+dnl #
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+dnl # The Linux 5.5 kernel updated percpu_ref_tryget() which is inlined by
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+dnl # blkg_tryget() to use rcu_read_lock() instead of rcu_read_lock_sched().
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+dnl # As a side effect the function was converted to GPL-only.
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+dnl #
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+AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKG_TRYGET], [
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+ ZFS_LINUX_TEST_SRC([blkg_tryget], [
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+ #include <linux/blk-cgroup.h>
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+ #include <linux/bio.h>
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+ #include <linux/fs.h>
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+ ],[
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+ struct blkcg_gq blkg __attribute__ ((unused));
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+ bool rc __attribute__ ((unused));
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+ rc = blkg_tryget(&blkg);
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+ ], [], [$ZFS_META_LICENSE])
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+])
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+
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+AC_DEFUN([ZFS_AC_KERNEL_BLKG_TRYGET], [
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+ AC_MSG_CHECKING([whether blkg_tryget() is available])
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+ ZFS_LINUX_TEST_RESULT([blkg_tryget], [
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+ AC_MSG_RESULT(yes)
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+ AC_DEFINE(HAVE_BLKG_TRYGET, 1, [blkg_tryget() is available])
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+
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+ AC_MSG_CHECKING([whether blkg_tryget() is GPL-only])
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+ ZFS_LINUX_TEST_RESULT([blkg_tryget_license], [
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+ AC_MSG_RESULT(no)
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+ ],[
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+ AC_MSG_RESULT(yes)
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+ AC_DEFINE(HAVE_BLKG_TRYGET_GPL_ONLY, 1,
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+ [blkg_tryget() GPL-only])
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+ ])
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+ ],[
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+ AC_MSG_RESULT(no)
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+ ])
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+])
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diff --git a/config/kernel.m4 b/config/kernel.m4
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index dce619729d4..bea6f9b1bbf 100644
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--- a/config/kernel.m4
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+++ b/config/kernel.m4
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@@ -70,6 +70,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
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ZFS_AC_KERNEL_SRC_BIO_BI_STATUS
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ZFS_AC_KERNEL_SRC_BIO_RW_BARRIER
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ZFS_AC_KERNEL_SRC_BIO_RW_DISCARD
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+ ZFS_AC_KERNEL_SRC_BLKG_TRYGET
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ZFS_AC_KERNEL_SRC_BLK_QUEUE_BDI
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ZFS_AC_KERNEL_SRC_BLK_QUEUE_DISCARD
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ZFS_AC_KERNEL_SRC_BLK_QUEUE_SECURE_ERASE
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@@ -186,6 +187,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
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ZFS_AC_KERNEL_BIO_BI_STATUS
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ZFS_AC_KERNEL_BIO_RW_BARRIER
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ZFS_AC_KERNEL_BIO_RW_DISCARD
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+ ZFS_AC_KERNEL_BLKG_TRYGET
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ZFS_AC_KERNEL_BLK_QUEUE_BDI
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ZFS_AC_KERNEL_BLK_QUEUE_DISCARD
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ZFS_AC_KERNEL_BLK_QUEUE_SECURE_ERASE
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diff --git a/module/zfs/vdev_disk.c b/module/zfs/vdev_disk.c
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index 661f0f1b727..8544bb8ffb6 100644
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--- a/module/zfs/vdev_disk.c
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+++ b/module/zfs/vdev_disk.c
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@@ -473,6 +473,36 @@ vdev_submit_bio_impl(struct bio *bio)
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#ifdef HAVE_BIO_SET_DEV
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#if defined(CONFIG_BLK_CGROUP) && defined(HAVE_BIO_SET_DEV_GPL_ONLY)
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+/*
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+ * The Linux 5.5 kernel updated percpu_ref_tryget() which is inlined by
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+ * blkg_tryget() to use rcu_read_lock() instead of rcu_read_lock_sched().
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+ * As a side effect the function was converted to GPL-only. Define our
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+ * own version when needed which uses rcu_read_lock_sched().
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+ */
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+#if defined(HAVE_BLKG_TRYGET_GPL_ONLY)
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+static inline bool
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+vdev_blkg_tryget(struct blkcg_gq *blkg)
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+{
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+ struct percpu_ref *ref = &blkg->refcnt;
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+ unsigned long __percpu *count;
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+ bool rc;
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+
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+ rcu_read_lock_sched();
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+
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+ if (__ref_is_percpu(ref, &count)) {
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+ this_cpu_inc(*count);
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+ rc = true;
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+ } else {
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+ rc = atomic_long_inc_not_zero(&ref->count);
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+ }
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+
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+ rcu_read_unlock_sched();
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+
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+ return (rc);
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+}
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+#elif defined(HAVE_BLKG_TRYGET)
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+#define vdev_blkg_tryget(bg) blkg_tryget(bg)
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+#endif
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/*
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* The Linux 5.0 kernel updated the bio_set_dev() macro so it calls the
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* GPL-only bio_associate_blkg() symbol thus inadvertently converting
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@@ -487,7 +517,7 @@ vdev_bio_associate_blkg(struct bio *bio)
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ASSERT3P(q, !=, NULL);
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ASSERT3P(bio->bi_blkg, ==, NULL);
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- if (q->root_blkg && blkg_tryget(q->root_blkg))
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+ if (q->root_blkg && vdev_blkg_tryget(q->root_blkg))
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bio->bi_blkg = q->root_blkg;
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}
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#define bio_associate_blkg vdev_bio_associate_blkg
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