[PATCH v2 3/3] f2fs: check if swapfile is section-alligned

[PATCH v2 3/3] f2fs: check if swapfile is section-alligned

[Huang Jianan]

If the swapfile isn't created by pin and fallocate, it can't be
guaranteed section-aligned, so it may be selected by f2fs gc. When
gc_pin_file_threshold is reached, the address of swapfile may change,
but won't be synchronized to swap_extent, so swap will write to wrong
address, which will cause data corruption.

Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Guo Weichao <guoweichao@oppo.com>
---
 fs/f2fs/data.c | 109 +++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 88 insertions(+), 21 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 4dbc1cafc55d..d33085daa3dc 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3781,11 +3781,64 @@ int f2fs_migrate_page(struct address_space *mapping,
 #endif
 
 #ifdef CONFIG_SWAP
+static int f2fs_is_file_aligned(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	block_t main_blkaddr = SM_I(sbi)->main_blkaddr;
+	block_t cur_lblock;
+	block_t last_lblock;
+	block_t pblock;
+	unsigned long nr_pblocks;
+	unsigned int blocks_per_sec = BLKS_PER_SEC(sbi);
+	int ret = 0;
+
+	cur_lblock = 0;
+	last_lblock = bytes_to_blks(inode, i_size_read(inode));
+
+	while (cur_lblock < last_lblock) {
+		struct f2fs_map_blocks map;
+
+		memset(&map, 0, sizeof(map));
+		map.m_lblk = cur_lblock;
+		map.m_len = last_lblock - cur_lblock;
+		map.m_next_pgofs = NULL;
+		map.m_next_extent = NULL;
+		map.m_seg_type = NO_CHECK_TYPE;
+		map.m_may_create = false;
+
+		ret = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_FIEMAP);
+		if (ret)
+			goto out;
+
+		/* hole */
+		if (!(map.m_flags & F2FS_MAP_FLAGS)) {
+			f2fs_err(sbi, "Swapfile has holes\n");
+			ret = -ENOENT;
+			goto out;
+		}
+
+		pblock = map.m_pblk;
+		nr_pblocks = map.m_len;
+
+		if ((pblock - main_blkaddr) & (blocks_per_sec - 1) ||
+			nr_pblocks & (blocks_per_sec - 1)) {
+			f2fs_err(sbi, "Swapfile does not align to section");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		cur_lblock += nr_pblocks;
+	}
+out:
+	return ret;
+}
+
 static int check_swap_activate_fast(struct swap_info_struct *sis,
 				struct file *swap_file, sector_t *span)
 {
 	struct address_space *mapping = swap_file->f_mapping;
 	struct inode *inode = mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	sector_t cur_lblock;
 	sector_t last_lblock;
 	sector_t pblock;
@@ -3793,8 +3846,8 @@ static int check_swap_activate_fast(struct swap_info_struct *sis,
 	sector_t highest_pblock = 0;
 	int nr_extents = 0;
 	unsigned long nr_pblocks;
-	u64 len;
-	int ret;
+	unsigned int blocks_per_sec = BLKS_PER_SEC(sbi);
+	int ret = 0;
 
 	/*
 	 * Map all the blocks into the extent list.  This code doesn't try
@@ -3802,31 +3855,41 @@ static int check_swap_activate_fast(struct swap_info_struct *sis,
 	 */
 	cur_lblock = 0;
 	last_lblock = bytes_to_blks(inode, i_size_read(inode));
-	len = i_size_read(inode);
 
 	while (cur_lblock + 1 <= last_lblock && cur_lblock < sis->max) {
 		struct f2fs_map_blocks map;
-		pgoff_t next_pgofs;
 
 		cond_resched();
 
 		memset(&map, 0, sizeof(map));
 		map.m_lblk = cur_lblock;
-		map.m_len = bytes_to_blks(inode, len) - cur_lblock;
-		map.m_next_pgofs = &next_pgofs;
+		map.m_len = last_lblock - cur_lblock;
+		map.m_next_pgofs = NULL;
+		map.m_next_extent = NULL;
 		map.m_seg_type = NO_CHECK_TYPE;
+		map.m_may_create = false;
 
 		ret = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_FIEMAP);
 		if (ret)
-			goto err_out;
+			goto out;
 
 		/* hole */
-		if (!(map.m_flags & F2FS_MAP_FLAGS))
-			goto err_out;
+		if (!(map.m_flags & F2FS_MAP_FLAGS)) {
+			f2fs_err(sbi, "Swapfile has holes\n");
+			ret = -ENOENT;
+			goto out;
+		}
 
 		pblock = map.m_pblk;
 		nr_pblocks = map.m_len;
 
+		if ((pblock - SM_I(sbi)->main_blkaddr) & (blocks_per_sec - 1) ||
+			nr_pblocks & (blocks_per_sec - 1)) {
+			f2fs_err(sbi, "Swapfile does not align to section");
+			ret = -EINVAL;
+			goto out;
+		}
+
 		if (cur_lblock + nr_pblocks >= sis->max)
 			nr_pblocks = sis->max - cur_lblock;
 
@@ -3855,9 +3918,6 @@ static int check_swap_activate_fast(struct swap_info_struct *sis,
 	sis->highest_bit = cur_lblock - 1;
 out:
 	return ret;
-err_out:
-	pr_err("swapon: swapfile has holes\n");
-	return -EINVAL;
 }
 
 /* Copied from generic_swapfile_activate() to check any holes */
@@ -3866,6 +3926,7 @@ static int check_swap_activate(struct swap_info_struct *sis,
 {
 	struct address_space *mapping = swap_file->f_mapping;
 	struct inode *inode = mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	unsigned blocks_per_page;
 	unsigned long page_no;
 	sector_t probe_block;
@@ -3873,11 +3934,15 @@ static int check_swap_activate(struct swap_info_struct *sis,
 	sector_t lowest_block = -1;
 	sector_t highest_block = 0;
 	int nr_extents = 0;
-	int ret;
+	int ret = 0;
 
 	if (PAGE_SIZE == F2FS_BLKSIZE)
 		return check_swap_activate_fast(sis, swap_file, span);
 
+	ret = f2fs_is_file_aligned(inode);
+	if (ret)
+		goto out;
+
 	blocks_per_page = bytes_to_blks(inode, PAGE_SIZE);
 
 	/*
@@ -3892,13 +3957,14 @@ static int check_swap_activate(struct swap_info_struct *sis,
 		unsigned block_in_page;
 		sector_t first_block;
 		sector_t block = 0;
-		int	 err = 0;
 
 		cond_resched();
 
 		block = probe_block;
-		err = bmap(inode, &block);
-		if (err || !block)
+		ret = bmap(inode, &block);
+		if (ret)
+			goto out;
+		if (!block)
 			goto bad_bmap;
 		first_block = block;
 
@@ -3914,9 +3980,10 @@ static int check_swap_activate(struct swap_info_struct *sis,
 					block_in_page++) {
 
 			block = probe_block + block_in_page;
-			err = bmap(inode, &block);
-
-			if (err || !block)
+			ret = bmap(inode, &block);
+			if (ret)
+				goto out;
+			if (!block)
 				goto bad_bmap;
 
 			if (block != first_block + block_in_page) {
@@ -3956,8 +4023,8 @@ static int check_swap_activate(struct swap_info_struct *sis,
 out:
 	return ret;
 bad_bmap:
-	pr_err("swapon: swapfile has holes\n");
-	return -EINVAL;
+	f2fs_err(sbi, "Swapfile has holes\n");
+	return -ENOENT;
 }
 
 static int f2fs_swap_activate(struct swap_info_struct *sis, struct file *file,
-- 
2.25.1

Re: [f2fs-dev] [PATCH v2 3/3] f2fs: check if swapfile is section-alligned

[Chao Yu]

On 2021/3/1 12:58, Huang Jianan via Linux-f2fs-devel wrote:
> If the swapfile isn't created by pin and fallocate, it can't be
> guaranteed section-aligned, so it may be selected by f2fs gc. When
> gc_pin_file_threshold is reached, the address of swapfile may change,
> but won't be synchronized to swap_extent, so swap will write to wrong
> address, which will cause data corruption.
> 
> Signed-off-by: Huang Jianan <huangjianan@oppo.com>
> Signed-off-by: Guo Weichao <guoweichao@oppo.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,