From: Mikulas Patocka <mpatocka@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org,
Chaitanya Kulkarni <chaitanyak@nvidia.com>,
Christoph Hellwig <hch@infradead.org>,
Li Nan <linan666@huaweicloud.com>,
dm-devel@redhat.com, Zdenek Kabelac <zkabelac@redhat.com>
Subject: [dm-devel] [PATCH v2 1/3] brd: extend the rcu regions to cover read and write
Date: Fri, 21 Jul 2023 15:49:29 +0200 (CEST) [thread overview]
Message-ID: <7d99fa-9c13-ab2a-acde-1f8bbc63bf3@redhat.com> (raw)
This patch extends the rcu regions, so that lookup followed by a read or
write of a page is done inside rcu read lock. This is needed for the
following patch that enables discard.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
---
drivers/block/brd.c | 8 ++++++++
1 file changed, 8 insertions(+)
Index: linux-2.6/drivers/block/brd.c
===================================================================
--- linux-2.6.orig/drivers/block/brd.c
+++ linux-2.6/drivers/block/brd.c
@@ -150,23 +150,27 @@ static void copy_to_brd(struct brd_devic
size_t copy;
copy = min_t(size_t, n, PAGE_SIZE - offset);
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
BUG_ON(!page);
dst = kmap_atomic(page);
memcpy(dst + offset, src, copy);
kunmap_atomic(dst);
+ rcu_read_unlock();
if (copy < n) {
src += copy;
sector += copy >> SECTOR_SHIFT;
copy = n - copy;
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
BUG_ON(!page);
dst = kmap_atomic(page);
memcpy(dst, src, copy);
kunmap_atomic(dst);
+ rcu_read_unlock();
}
}
@@ -182,6 +186,7 @@ static void copy_from_brd(void *dst, str
size_t copy;
copy = min_t(size_t, n, PAGE_SIZE - offset);
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
if (page) {
src = kmap_atomic(page);
@@ -189,11 +194,13 @@ static void copy_from_brd(void *dst, str
kunmap_atomic(src);
} else
memset(dst, 0, copy);
+ rcu_read_unlock();
if (copy < n) {
dst += copy;
sector += copy >> SECTOR_SHIFT;
copy = n - copy;
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
if (page) {
src = kmap_atomic(page);
@@ -201,6 +208,7 @@ static void copy_from_brd(void *dst, str
kunmap_atomic(src);
} else
memset(dst, 0, copy);
+ rcu_read_unlock();
}
}
--
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https://listman.redhat.com/mailman/listinfo/dm-devel
WARNING: multiple messages have this Message-ID (diff)
From: Mikulas Patocka <mpatocka@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Li Nan <linan666@huaweicloud.com>,
Zdenek Kabelac <zkabelac@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
Chaitanya Kulkarni <chaitanyak@nvidia.com>,
linux-block@vger.kernel.org, dm-devel@redhat.com
Subject: [PATCH v2 1/3] brd: extend the rcu regions to cover read and write
Date: Fri, 21 Jul 2023 15:49:29 +0200 (CEST) [thread overview]
Message-ID: <7d99fa-9c13-ab2a-acde-1f8bbc63bf3@redhat.com> (raw)
This patch extends the rcu regions, so that lookup followed by a read or
write of a page is done inside rcu read lock. This is needed for the
following patch that enables discard.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
---
drivers/block/brd.c | 8 ++++++++
1 file changed, 8 insertions(+)
Index: linux-2.6/drivers/block/brd.c
===================================================================
--- linux-2.6.orig/drivers/block/brd.c
+++ linux-2.6/drivers/block/brd.c
@@ -150,23 +150,27 @@ static void copy_to_brd(struct brd_devic
size_t copy;
copy = min_t(size_t, n, PAGE_SIZE - offset);
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
BUG_ON(!page);
dst = kmap_atomic(page);
memcpy(dst + offset, src, copy);
kunmap_atomic(dst);
+ rcu_read_unlock();
if (copy < n) {
src += copy;
sector += copy >> SECTOR_SHIFT;
copy = n - copy;
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
BUG_ON(!page);
dst = kmap_atomic(page);
memcpy(dst, src, copy);
kunmap_atomic(dst);
+ rcu_read_unlock();
}
}
@@ -182,6 +186,7 @@ static void copy_from_brd(void *dst, str
size_t copy;
copy = min_t(size_t, n, PAGE_SIZE - offset);
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
if (page) {
src = kmap_atomic(page);
@@ -189,11 +194,13 @@ static void copy_from_brd(void *dst, str
kunmap_atomic(src);
} else
memset(dst, 0, copy);
+ rcu_read_unlock();
if (copy < n) {
dst += copy;
sector += copy >> SECTOR_SHIFT;
copy = n - copy;
+ rcu_read_lock();
page = brd_lookup_page(brd, sector);
if (page) {
src = kmap_atomic(page);
@@ -201,6 +208,7 @@ static void copy_from_brd(void *dst, str
kunmap_atomic(src);
} else
memset(dst, 0, copy);
+ rcu_read_unlock();
}
}
next reply other threads:[~2023-07-21 13:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20230727083159eucas1p1c4b907caac8371200bbd465143ac39fd@eucas1p1.samsung.com>
2023-07-21 13:49 ` Mikulas Patocka [this message]
2023-07-21 13:49 ` [PATCH v2 1/3] brd: extend the rcu regions to cover read and write Mikulas Patocka
2023-07-27 8:31 ` [dm-devel] " Pankaj Raghav
2023-07-27 8:31 ` Pankaj Raghav
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