f2fs crypto: fix racing of accessing encrypted page among different competitors

From 0211c6ed82440891b3369851d079f6c69b432b6c Mon Sep 17 00:00:00 2001

Quoted 1 line

From 0211c6ed82440891b3369851d079f6c69b432b6c Mon Sep 17 00:00:00 2001

From: Chao Yu <[email protected]>
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 <[email protected]>

---
 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(-)

fs/f2fs/data.c +11 -9

index 40a0102..d791bd3 100644
@@ -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))

fs/f2fs/f2fs.h +1 -0

index a7522a4..dc4d30b 100644
@@ -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 *,

fs/f2fs/file.c +5 -0

index e2d9910..1d2df88 100644
@@ -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:

fs/f2fs/gc.c +5 -1

index e7cec86..2493fd6 100644
@@ -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;
+	}
+
+	/*

fs/f2fs/gc.c +0 -0

 	if (clear_page_dirty_for_io(fio.encrypted_page))
 		dec_page_count(fio.sbi, F2FS_DIRTY_META);
 

fs/f2fs/segment.c +17 -0

index 3c546eb..d5d760c 100644
@@ -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);

Signature · 1 line

2.5.2

-----Original Message-----
From: Jaegeuk Kim [mailto:[email protected]]
Sent: Tuesday, October 13, 2015 5:00 AM
To: Chao Yu
Cc: [email protected]; [email protected]
Subject: Re: [PATCH] f2fs crypto: fix racing of accessing encrypted page among different competitors

fs/f2fs/f2fs.h void f2fs_replace_block(struct f2fs_sb_info *, struct dnode_of_data

Quoted 118 lines · Chao Yu

Quoted 1 line

From 0211c6ed82440891b3369851d079f6c69b432b6c Mon Sep 17 00:00:00 2001

From: Chao Yu <[email protected]>
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 <[email protected]>

---
 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(-)

fs/f2fs/data.c +11 -9

index 40a0102..d791bd3 100644
@@ -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))

fs/f2fs/f2fs.h +0 -0

index a7522a4..dc4d30b 100644
@@ -1778,6 +1778,7 @@ void f2fs_replace_block(struct f2fs_sb_info *, struct dnode_of_data

*,

Quoted 43 lines

fs/f2fs/f2fs.h +1 -0

 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 *,

fs/f2fs/file.c +5 -0

index e2d9910..1d2df88 100644
@@ -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:

fs/f2fs/gc.c +9 -1

index e7cec86..2493fd6 100644
@@ -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);
 

fs/f2fs/gc.c static void move_encrypted_block(struct inode *inode, block_t bidx) · line 569

Quoted 5 lines

fs/f2fs/gc.c +0 -1

 	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.

Quoted 7 lines

fs/f2fs/gc.c +0 -0

 	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;
 

fs/f2fs/gc.c static void move_encrypted_block(struct inode *inode, block_t bidx) · line 599

Quoted 3 lines

fs/f2fs/gc.c +1 -1

 	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?

Quoted 34 lines

fs/f2fs/gc.c +0 -0

 	if (clear_page_dirty_for_io(fio.encrypted_page))
 		dec_page_count(fio.sbi, F2FS_DIRTY_META);
 

fs/f2fs/segment.c +17 -1

index 3c546eb..d5d760c 100644
@@ -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

Quoted 171 lines

-----Original Message-----
From: Jaegeuk Kim [mailto:[email protected]]
Sent: Tuesday, October 13, 2015 5:00 AM
To: Chao Yu
Cc: [email protected]; [email protected]
Subject: Re: [PATCH] f2fs crypto: fix racing of accessing encrypted page among different competitors

fs/f2fs/f2fs.h void f2fs_replace_block(struct f2fs_sb_info *, struct dnode_of_data

Quoted 118 lines · Chao Yu

Quoted 1 line

From 0211c6ed82440891b3369851d079f6c69b432b6c Mon Sep 17 00:00:00 2001

From: Chao Yu <[email protected]>
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 <[email protected]>

---
 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(-)

fs/f2fs/data.c +11 -9

index 40a0102..d791bd3 100644
@@ -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))

fs/f2fs/f2fs.h +0 -0

index a7522a4..dc4d30b 100644
@@ -1778,6 +1778,7 @@ void f2fs_replace_block(struct f2fs_sb_info *, struct dnode_of_data

*,

Quoted 43 lines

fs/f2fs/f2fs.h +1 -0

 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 *,

fs/f2fs/file.c +5 -0

index e2d9910..1d2df88 100644
@@ -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:

fs/f2fs/gc.c +9 -1

index e7cec86..2493fd6 100644
@@ -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);
 

Quoted 7 lines

fs/f2fs/gc.c static void move_encrypted_block(struct inode *inode, block_t bidx) · line 569

Quoted 5 lines

fs/f2fs/gc.c +0 -1

 	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.

Quoted 7 lines

Quoted 7 lines

fs/f2fs/gc.c +0 -0

 	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;
 

Quoted 5 lines

fs/f2fs/gc.c static void move_encrypted_block(struct inode *inode, block_t bidx) · line 599

Quoted 3 lines

fs/f2fs/gc.c +1 -1

 	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?

Thanks,

Quoted 34 lines

Quoted 34 lines

fs/f2fs/gc.c +0 -0

 	if (clear_page_dirty_for_io(fio.encrypted_page))
 		dec_page_count(fio.sbi, F2FS_DIRTY_META);
 

fs/f2fs/segment.c +17 -1

index 3c546eb..d5d760c 100644
@@ -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

-----Original Message-----
From: Jaegeuk Kim [mailto:[email protected]]
Sent: Wednesday, October 14, 2015 12:52 AM
To: Chao Yu
Cc: [email protected]; [email protected]
Subject: Re: [PATCH] f2fs crypto: fix racing of accessing encrypted page among different competitors

Quoted 194 lines · Chao Yu

Quoted 171 lines

-----Original Message-----
From: Jaegeuk Kim [mailto:[email protected]]
Sent: Tuesday, October 13, 2015 5:00 AM
To: Chao Yu
Cc: [email protected]; [email protected]
Subject: Re: [PATCH] f2fs crypto: fix racing of accessing encrypted page among different competitors

fs/f2fs/f2fs.h void f2fs_replace_block(struct f2fs_sb_info *, struct dnode_of_data

Quoted 118 lines · Chao Yu

Quoted 1 line

From 0211c6ed82440891b3369851d079f6c69b432b6c Mon Sep 17 00:00:00 2001

From: Chao Yu <[email protected]>
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 <[email protected]>

---
 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(-)

fs/f2fs/data.c +11 -9

index 40a0102..d791bd3 100644
@@ -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))

fs/f2fs/f2fs.h +0 -0

index a7522a4..dc4d30b 100644
@@ -1778,6 +1778,7 @@ void f2fs_replace_block(struct f2fs_sb_info *, struct dnode_of_data

*,

Quoted 43 lines

fs/f2fs/f2fs.h +1 -0

 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 *,

fs/f2fs/file.c +5 -0

index e2d9910..1d2df88 100644
@@ -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:

fs/f2fs/gc.c +9 -1

index e7cec86..2493fd6 100644
@@ -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);
 

Quoted 7 lines

fs/f2fs/gc.c static void move_encrypted_block(struct inode *inode, block_t bidx) · line 569

Quoted 5 lines

fs/f2fs/gc.c +0 -1

 	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.

Quoted 12 lines

fs/f2fs/gc.c static void move_encrypted_block(struct inode *inode, block_t bidx) · line 599

Quoted 10 lines

fs/f2fs/gc.c +1 -1

 	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?

Quoted 3 lines

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,

Quoted 37 lines

Thanks,

Quoted 34 lines

Quoted 34 lines

fs/f2fs/gc.c +0 -0

 	if (clear_page_dirty_for_io(fio.encrypted_page))
 		dec_page_count(fio.sbi, F2FS_DIRTY_META);
 

fs/f2fs/segment.c +17 -1

index 3c546eb..d5d760c 100644
@@ -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