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Date:   Sat, 27 Feb 2021 20:02:31 +0800
From:   Huang Jianan <huangjianan@...o.com>
To:     linux-f2fs-devel@...ts.sourceforge.net
Cc:     huangjianan@...o.com, guoweichao@...o.com, zhangshiming@...o.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] f2fs: check if swapfile is section-alligned

If the swapfile isn't created by pin and fallocate, it cann'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 synchroniz to swap_extent, so swap will write to wrong
address, which will cause data corruption.

Signed-off-by: Huang Jianan <huangjianan@...o.com>
Signed-off-by: Guo Weichao <guoweichao@...o.com>
---
 fs/f2fs/data.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 4dbc1cafc55d..3e523d6e4643 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3781,11 +3781,63 @@ int f2fs_migrate_page(struct address_space *mapping,
 #endif
 
 #ifdef CONFIG_SWAP
+static int f2fs_check_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 len;
+	unsigned long nr_pblocks;
+	unsigned int blocks_per_sec = sbi->blocks_per_seg * sbi->segs_per_sec;
+	int ret;
+
+	cur_lblock = 0;
+	last_lblock = bytes_to_blks(inode, i_size_read(inode));
+	len = i_size_read(inode);
+
+	while (cur_lblock < last_lblock) {
+		struct f2fs_map_blocks map;
+		pgoff_t next_pgofs;
+
+		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_seg_type = NO_CHECK_TYPE;
+
+		ret = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_FIEMAP);
+
+		if (ret)
+			goto err_out;
+
+		/* hole */
+		if (!(map.m_flags & F2FS_MAP_FLAGS))
+			goto err_out;
+
+		pblock = map.m_pblk;
+		nr_pblocks = map.m_len;
+
+		if ((pblock - main_blkaddr) & (blocks_per_sec - 1) ||
+			nr_pblocks & (blocks_per_sec - 1))
+			goto err_out;
+
+		cur_lblock += nr_pblocks;
+	}
+
+	return 0;
+err_out:
+	pr_err("swapon: swapfile isn't section-aligned\n");
+	return -EINVAL;
+}
+
 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;
@@ -3793,6 +3845,7 @@ static int check_swap_activate_fast(struct swap_info_struct *sis,
 	sector_t highest_pblock = 0;
 	int nr_extents = 0;
 	unsigned long nr_pblocks;
+	unsigned int blocks_per_sec = sbi->blocks_per_seg * sbi->segs_per_sec;
 	u64 len;
 	int ret;
 
@@ -3827,6 +3880,13 @@ static int check_swap_activate_fast(struct swap_info_struct *sis,
 		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)) {
+			pr_err("swapon: swapfile isn't section-aligned\n");
+			ret = -EINVAL;
+			goto out;
+		}
+
 		if (cur_lblock + nr_pblocks >= sis->max)
 			nr_pblocks = sis->max - cur_lblock;
 
@@ -3878,6 +3938,9 @@ static int check_swap_activate(struct swap_info_struct *sis,
 	if (PAGE_SIZE == F2FS_BLKSIZE)
 		return check_swap_activate_fast(sis, swap_file, span);
 
+	if (f2fs_check_file_aligned(inode))
+		return -EINVAL;
+
 	blocks_per_page = bytes_to_blks(inode, PAGE_SIZE);
 
 	/*
-- 
2.25.1

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