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f2fs: fix cgroup writeback accounting with fs-layer encryption

PATCH Applied Eric Biggers 4 participants 4 messages Feb 3, 2023 – Feb 6, 2023

Subsystems (4)
Stable branch VFS F2FS file system fscrypt: file system level encryption support
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Eric Biggers

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#0 lore raw

PATCH 1/1 f2fs: fix cgroup writeback accounting with fs-layer encryption

From: Eric Biggers <[email protected]>

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 [email protected]
Reported-by Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by Eric Biggers <[email protected]>
---
 fs/f2fs/data.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
fs/f2fs/data.c +3 -3
index 754841bce389f..8a636500db0ef 100644
@@ -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

Signature · 1 line
2.39.1
maintainer Reviewed-by on v1 1/1
#1 lore raw
Quoted 12 lines · Eric Biggers

From: Eric Biggers <[email protected]>

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.

Quoted 7 lines

Fix this by always passing the pagecache page to
wbc_account_cgroup_owner().

Fixes 578c647879f7 ("f2fs: implement cgroup writeback support")
Cc [email protected]
Reported-by Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by Eric Biggers <[email protected]>
Reviewed-by Chao Yu <[email protected]>

Thanks,

_______________________________________________
Linux-f2fs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Acked-by on v1 1/1
#2 lore raw
In reply to Eric Biggers
Quoted 12 lines · Eric Biggers

From: Eric Biggers <[email protected]>

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.

Quoted 7 lines

Fix this by always passing the pagecache page to
wbc_account_cgroup_owner().

Fixes 578c647879f7 ("f2fs: implement cgroup writeback support")
Cc [email protected]
Reported-by Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by Eric Biggers <[email protected]>
Acked-by Tejun Heo <[email protected]>

Thanks.

Signature · 1 line
tejun
CI Applied
#3 lore raw
In reply to Eric Biggers
This patch was applied to jaegeuk/f2fs.git (dev) by Jaegeuk Kim <[email protected]>:

Hello:

This patch was applied to jaegeuk/f2fs.git (dev)
by Jaegeuk Kim <[email protected]>:

Quoted 6 lines · On Thu, 2 Feb 2023 17:02:39 -0800 you wrote:

From: Eric Biggers <[email protected]>

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.

Quoted 7 lines

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!

Signature · 2 lines
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