[PATCH] f2fs: fix cgroup writeback accounting with fs-layer encryption

[PATCH] f2fs: fix cgroup writeback accounting with fs-layer encryption

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

When writing a page from an encrypted file that is using
filesystem-layer encryption (not inline encryption), f2fs 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: 578c647879f7 ("f2fs: implement cgroup writeback support")
Cc: stable@vger.kernel.org
Reported-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/f2fs/data.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 754841bce389f..8a636500db0ef 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -739,7 +739,7 @@ int f2fs_submit_page_bio(struct f2fs_io_info *fio)
 	}
 
 	if (fio->io_wbc && !is_read_io(fio->op))
-		wbc_account_cgroup_owner(fio->io_wbc, page, PAGE_SIZE);
+		wbc_account_cgroup_owner(fio->io_wbc, fio->page, PAGE_SIZE);
 
 	inc_page_count(fio->sbi, is_read_io(fio->op) ?
 			__read_io_type(page) : WB_DATA_TYPE(fio->page));
@@ -949,7 +949,7 @@ int f2fs_merge_page_bio(struct f2fs_io_info *fio)
 	}
 
 	if (fio->io_wbc)
-		wbc_account_cgroup_owner(fio->io_wbc, page, PAGE_SIZE);
+		wbc_account_cgroup_owner(fio->io_wbc, fio->page, PAGE_SIZE);
 
 	inc_page_count(fio->sbi, WB_DATA_TYPE(page));
 
@@ -1023,7 +1023,7 @@ void f2fs_submit_page_write(struct f2fs_io_info *fio)
 	}
 
 	if (fio->io_wbc)
-		wbc_account_cgroup_owner(fio->io_wbc, bio_page, PAGE_SIZE);
+		wbc_account_cgroup_owner(fio->io_wbc, fio->page, PAGE_SIZE);
 
 	io->last_block_in_bio = fio->new_blkaddr;
 

base-commit: de6b3a5e09b29c014bd04044b023896107cfa2ee
-- 
2.39.1

Re: [f2fs-dev] [PATCH] f2fs: fix cgroup writeback accounting with fs-layer encryption

[Chao Yu]

On 2023/2/3 9:02, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> When writing a page from an encrypted file that is using
> filesystem-layer encryption (not inline encryption), f2fs 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: 578c647879f7 ("f2fs: implement cgroup writeback support")
> Cc: stable@vger.kernel.org
> Reported-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

Re: [PATCH] f2fs: fix cgroup writeback accounting with fs-layer encryption

[Tejun Heo]

On Thu, Feb 02, 2023 at 05:02:39PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> When writing a page from an encrypted file that is using
> filesystem-layer encryption (not inline encryption), f2fs 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: 578c647879f7 ("f2fs: implement cgroup writeback support")
> Cc: stable@vger.kernel.org
> Reported-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun

Re: [f2fs-dev] [PATCH] f2fs: fix cgroup writeback accounting with fs-layer encryption

[patchwork-bot+f2fs]

Hello:

This patch was applied to jaegeuk/f2fs.git (dev)
by Jaegeuk Kim <jaegeuk@kernel.org>:

On Thu,  2 Feb 2023 17:02:39 -0800 you wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> When writing a page from an encrypted file that is using
> filesystem-layer encryption (not inline encryption), f2fs 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.
> 
> [...]

Here is the summary with links:
  - [f2fs-dev] f2fs: fix cgroup writeback accounting with fs-layer encryption
    https://git.kernel.org/jaegeuk/f2fs/c/844545c51a5b

You are awesome, thank you!
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