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Message-ID: <20151013164904.GA60592@jaegeuk-mac02.mot.com>
Date: Tue, 13 Oct 2015 09:51:44 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] f2fs crypto: fix racing of accessing encrypted page
among different competitors
On Tue, Oct 13, 2015 at 02:01:10PM +0800, Chao Yu wrote:
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk@...nel.org]
> > Sent: Tuesday, October 13, 2015 5:00 AM
> > To: Chao Yu
> > Cc: linux-f2fs-devel@...ts.sourceforge.net; linux-kernel@...r.kernel.org
> > Subject: Re: [PATCH] f2fs crypto: fix racing of accessing encrypted page among different
> > competitors
> >
> > On Thu, Oct 08, 2015 at 08:50:39PM +0800, Chao Yu wrote:
> > > >From 0211c6ed82440891b3369851d079f6c69b432b6c Mon Sep 17 00:00:00 2001
> > > From: Chao Yu <chao2.yu@...sung.com>
> > > Date: Thu, 8 Oct 2015 13:27:34 +0800
> > > Subject: [PATCH] f2fs crypto: fix racing of accessing encrypted page among
> > > different competitors
> > >
> > > Since we use different page cache (normally inode's page cache for R/W
> > > and meta inode's page cache for GC) to cache the same physical block
> > > which is belong to an encrypted inode. Writeback of these two page
> > > cache should be exclusive, but now we didn't handle writeback state
> > > well, so there may be potential racing problem:
> > >
> > > a)
> > > kworker: f2fs_gc:
> > > - f2fs_write_data_pages
> > > - f2fs_write_data_page
> > > - do_write_data_page
> > > - write_data_page
> > > - f2fs_submit_page_mbio
> > > (page#1 in inode's page cache was queued
> > > in f2fs bio cache, and be ready to write
> > > to new blkaddr)
> > > - gc_data_segment
> > > - move_encrypted_block
> > > - pagecache_get_page
> > > (page#2 in meta inode's page cache
> > > was cached with the invalid datas
> > > of physical block located in new
> > > blkaddr)
> > > - f2fs_submit_page_mbio
> > > (page#1 was submitted, later, page#2
> > > with invalid data will be submitted)
> > >
> > > b)
> > > f2fs_gc:
> > > - gc_data_segment
> > > - move_encrypted_block
> > > - f2fs_submit_page_mbio
> > > (page#1 in meta inode's page cache was
> > > queued in f2fs bio cache, and be ready
> > > to write to new blkaddr)
> > > user thread:
> > > - f2fs_write_begin
> > > - f2fs_submit_page_bio
> > > (we submit the request to block layer
> > > to update page#2 in inode's page cache
> > > with physical block located in new
> > > blkaddr, so here we may read gabbage
> > > data from new blkaddr since GC hasn't
> > > writebacked the page#1 yet)
> > >
> > > This patch fixes above potential racing problem for encrypted inode.
> > >
> > > Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> > > ---
> > > fs/f2fs/data.c | 20 +++++++++++---------
> > > fs/f2fs/f2fs.h | 1 +
> > > fs/f2fs/file.c | 5 +++++
> > > fs/f2fs/gc.c | 13 ++++++++++---
> > > fs/f2fs/segment.c | 17 +++++++++++++++++
> > > 5 files changed, 44 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > > index 40a0102..d791bd3 100644
> > > --- a/fs/f2fs/data.c
> > > +++ b/fs/f2fs/data.c
> > > @@ -954,21 +954,14 @@ submit_and_realloc:
> > >
> > > if (f2fs_encrypted_inode(inode) &&
> > > S_ISREG(inode->i_mode)) {
> > > - struct page *cpage;
> > >
> > > ctx = f2fs_get_crypto_ctx(inode);
> > > if (IS_ERR(ctx))
> > > goto set_error_page;
> > >
> > > /* wait the page to be moved by cleaning */
> > > - cpage = find_lock_page(
> > > - META_MAPPING(F2FS_I_SB(inode)),
> > > - block_nr);
> > > - if (cpage) {
> > > - f2fs_wait_on_page_writeback(cpage,
> > > - DATA);
> > > - f2fs_put_page(cpage, 1);
> > > - }
> > > + f2fs_wait_on_encrypted_page_writeback(
> > > + F2FS_I_SB(inode), block_nr);
> > > }
> > >
> > > bio = bio_alloc(GFP_KERNEL,
> > > @@ -1059,6 +1052,11 @@ int do_write_data_page(struct f2fs_io_info *fio)
> > > }
> > >
> > > if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
> > > +
> > > + /* wait for GCed encrypted page writeback */
> > > + f2fs_wait_on_encrypted_page_writeback(F2FS_I_SB(inode),
> > > + fio->blk_addr);
> > > +
> > > fio->encrypted_page = f2fs_encrypt(inode, fio->page);
> > > if (IS_ERR(fio->encrypted_page)) {
> > > err = PTR_ERR(fio->encrypted_page);
> > > @@ -1446,6 +1444,10 @@ put_next:
> > >
> > > f2fs_wait_on_page_writeback(page, DATA);
> > >
> > > + /* wait for GCed encrypted page writeback */
> > > + if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
> > > + f2fs_wait_on_encrypted_page_writeback(sbi, dn.data_blkaddr);
> > > +
> > > if (len == PAGE_CACHE_SIZE)
> > > goto out_update;
> > > if (PageUptodate(page))
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index a7522a4..dc4d30b 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -1778,6 +1778,7 @@ void f2fs_replace_block(struct f2fs_sb_info *, struct dnode_of_data
> > *,
> > > void allocate_data_block(struct f2fs_sb_info *, struct page *,
> > > block_t, block_t *, struct f2fs_summary *, int);
> > > void f2fs_wait_on_page_writeback(struct page *, enum page_type);
> > > +void f2fs_wait_on_encrypted_page_writeback(struct f2fs_sb_info *, block_t);
> > > void write_data_summaries(struct f2fs_sb_info *, block_t);
> > > void write_node_summaries(struct f2fs_sb_info *, block_t);
> > > int lookup_journal_in_cursum(struct f2fs_summary_block *,
> > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > index e2d9910..1d2df88 100644
> > > --- a/fs/f2fs/file.c
> > > +++ b/fs/f2fs/file.c
> > > @@ -87,6 +87,11 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
> > > mapped:
> > > /* fill the page */
> > > f2fs_wait_on_page_writeback(page, DATA);
> > > +
> > > + /* wait for GCed encrypted page writeback */
> > > + if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode))
> > > + f2fs_wait_on_encrypted_page_writeback(sbi, dn.data_blkaddr);
> > > +
> > > /* if gced page is attached, don't write to cold segment */
> > > clear_cold_data(page);
> > > out:
> > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > > index e7cec86..2493fd6 100644
> > > --- a/fs/f2fs/gc.c
> > > +++ b/fs/f2fs/gc.c
> > > @@ -559,14 +559,21 @@ static void move_encrypted_block(struct inode *inode, block_t bidx)
> > > if (err)
> > > goto out;
> > >
> > > - if (unlikely(dn.data_blkaddr == NULL_ADDR))
> > > + if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
> > > + ClearPageUptodate(page);
> > > goto put_out;
> > > + }
> > > +
> > > + /*
> > > + * don't cache encrypted data into meta inode until previous dirty
> > > + * data were writebacked to avoid racing between GC and flush.
> > > + */
> > > + f2fs_wait_on_page_writeback(page, DATA);
> > >
> > > get_node_info(fio.sbi, dn.nid, &ni);
> > > set_summary(&sum, dn.nid, dn.ofs_in_node, ni.version);
> > >
> > > /* read page */
> > > - fio.page = page;
> >
> > Let's remain just to make sure.
>
> OK.
>
> >
> > > fio.blk_addr = dn.data_blkaddr;
> > >
> > > fio.encrypted_page = pagecache_get_page(META_MAPPING(fio.sbi),
> > > @@ -589,7 +596,7 @@ static void move_encrypted_block(struct inode *inode, block_t bidx)
> > > goto put_page_out;
> > >
> > > set_page_dirty(fio.encrypted_page);
> > > - f2fs_wait_on_page_writeback(fio.encrypted_page, META);
> > > + f2fs_wait_on_page_writeback(fio.encrypted_page, DATA);
> >
> > Why DATA?
>
> This is because we only submit the encrypted page in to DATA type bio
> cache, so we should check whether the page is cached or not in DATA
> type bio, rather than META type cache. Right?
Oh, right, type was DATA. :)
I'll test this patch with adding the above initialization.
Thanks,
>
> Thanks,
>
> >
> > > if (clear_page_dirty_for_io(fio.encrypted_page))
> > > dec_page_count(fio.sbi, F2FS_DIRTY_META);
> > >
> > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > > index 3c546eb..d5d760c 100644
> > > --- a/fs/f2fs/segment.c
> > > +++ b/fs/f2fs/segment.c
> > > @@ -1462,6 +1462,23 @@ void f2fs_wait_on_page_writeback(struct page *page,
> > > }
> > > }
> > >
> > > +void f2fs_wait_on_encrypted_page_writeback(struct f2fs_sb_info *sbi,
> > > + block_t blkaddr)
> > > +{
> > > + struct page *cpage;
> > > +
> > > + if (blkaddr == NEW_ADDR)
> > > + return;
> > > +
> > > + f2fs_bug_on(sbi, blkaddr == NULL_ADDR);
> > > +
> > > + cpage = find_lock_page(META_MAPPING(sbi), blkaddr);
> > > + if (cpage) {
> > > + f2fs_wait_on_page_writeback(cpage, DATA);
> > > + f2fs_put_page(cpage, 1);
> > > + }
> > > +}
> > > +
> > > static int read_compacted_summaries(struct f2fs_sb_info *sbi)
> > > {
> > > struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
> > > --
> > > 2.5.2
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