From: Eric Biggers <ebiggers@xxxxxxxxxx>
commit ffec85d53d0f39ee4680a2cf0795255e000e1feb upstream.
When writing a page from an encrypted file that is using
filesystem-layer encryption (not inline encryption), ext4 encrypts the
pagecache page into a bounce page, then writes the bounce page.
It also passes the bounce page to wbc_account_cgroup_owner(). That's
incorrect, because the bounce page is a newly allocated temporary page
that doesn't have the memory cgroup of the original pagecache page.
This makes wbc_account_cgroup_owner() not account the I/O to the owner
of the pagecache page as it should.
Fix this by always passing the pagecache page to
wbc_account_cgroup_owner().
Fixes: 001e4a8775f6 ("ext4: implement cgroup writeback support")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230203005503.141557-1-ebiggers@xxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
---
fs/ext4/page-io.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index b66b335a0ca6f..5858fb9b5cd53 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -380,7 +380,8 @@ static int io_submit_init_bio(struct ext4_io_submit *io,
static int io_submit_add_bh(struct ext4_io_submit *io,
struct inode *inode,
- struct page *page,
+ struct page *pagecache_page,
+ struct page *bounce_page,
struct buffer_head *bh)
{
int ret;
@@ -395,10 +396,11 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
return ret;
io->io_bio->bi_write_hint = inode->i_write_hint;
}
- ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
+ ret = bio_add_page(io->io_bio, bounce_page ?: pagecache_page,
+ bh->b_size, bh_offset(bh));
if (ret != bh->b_size)
goto submit_and_retry;
- wbc_account_cgroup_owner(io->io_wbc, page, bh->b_size);
+ wbc_account_cgroup_owner(io->io_wbc, pagecache_page, bh->b_size);
io->io_next_block++;
return 0;
}
@@ -511,7 +513,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
do {
if (!buffer_async_write(bh))
continue;
- ret = io_submit_add_bh(io, inode, bounce_page ?: page, bh);
+ ret = io_submit_add_bh(io, inode, page, bounce_page, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
--
2.39.2
