[PATCH v2] f2fs: compress: do sanity check on cluster

[Chao Yu <chao@kernel.org>]

This patch adds f2fs_sanity_check_cluster() to support doing
sanity check on cluster of compressed file, it will be triggered
from below two paths:

- __f2fs_cluster_blocks()
- f2fs_map_blocks(F2FS_GET_BLOCK_FIEMAP)

And it can detect below three kind of cluster insanity status.

C: COMPRESS_ADDR
N: NULL_ADDR or NEW_ADDR
V: valid blkaddr
*: any value

1. [*|C|*|*]
2. [C|*|C|*]
3. [C|N|N|V]

Signed-off-by: Chao Yu <chao@kernel.org>
---
v2:
- cover all map_block cases
- give EFSCORRUPTED only when CHECK_FS is enabled for fiemap()
 fs/f2fs/compress.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/f2fs/data.c     |  9 ++++++++
 fs/f2fs/f2fs.h     |  1 +
 3 files changed, 63 insertions(+)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 7dbfd6965b97..f25b32a6893a 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -898,6 +898,54 @@ static bool cluster_has_invalid_data(struct compress_ctx *cc)
 	return false;
 }
 
+bool f2fs_sanity_check_cluster(struct dnode_of_data *dn)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
+	unsigned int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
+	bool compressed = dn->data_blkaddr == COMPRESS_ADDR;
+	int cluster_end = 0;
+	int i;
+	char *reason = "";
+
+	if (!compressed)
+		return false;
+
+	/* [..., COMPR_ADDR, ...] */
+	if (dn->ofs_in_node % cluster_size) {
+		reason = "[*|C|*|*]";
+		goto out;
+	}
+
+	for (i = 1; i < cluster_size; i++) {
+		block_t blkaddr = data_blkaddr(dn->inode, dn->node_page,
+							dn->ofs_in_node + i);
+
+		/* [COMPR_ADDR, ..., COMPR_ADDR] */
+		if (blkaddr == COMPRESS_ADDR) {
+			reason = "[C|*|C|*]";
+			goto out;
+		}
+		if (compressed) {
+			if (!__is_valid_data_blkaddr(blkaddr)) {
+				if (!cluster_end)
+					cluster_end = i;
+				continue;
+			}
+			/* [COMPR_ADDR, NULL_ADDR or NEW_ADDR, valid_blkaddr] */
+			if (cluster_end) {
+				reason = "[C|N|N|V]";
+				goto out;
+			}
+		}
+	}
+	return false;
+out:
+	f2fs_warn(sbi, "access invalid cluster, ino:%lu, nid:%u, ofs_in_node:%u, reason:%s",
+			dn->inode->i_ino, dn->nid, dn->ofs_in_node, reason);
+	set_sbi_flag(sbi, SBI_NEED_FSCK);
+	return true;
+}
+
 static int __f2fs_cluster_blocks(struct inode *inode,
 				unsigned int cluster_idx, bool compr)
 {
@@ -915,6 +963,11 @@ static int __f2fs_cluster_blocks(struct inode *inode,
 		goto fail;
 	}
 
+	if (f2fs_sanity_check_cluster(&dn)) {
+		ret = -EFSCORRUPTED;
+		goto fail;
+	}
+
 	if (dn.data_blkaddr == COMPRESS_ADDR) {
 		int i;
 
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index df5e8d8c654e..d4c9aeba0842 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1552,6 +1552,15 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
 			map->m_flags |= F2FS_MAP_NEW;
 			blkaddr = dn.data_blkaddr;
 		} else {
+#ifdef CONFIG_F2FS_FS_COMPRESSION
+			if (f2fs_compressed_file(inode) &&
+					f2fs_sanity_check_cluster(&dn) &&
+					(flag != F2FS_GET_BLOCK_FIEMAP ||
+					IS_ENABLED(CONFIG_F2FS_CHECK_FS))) {
+				err = -EFSCORRUPTED;
+				goto sync_out;
+			}
+#endif
 			if (flag == F2FS_GET_BLOCK_BMAP) {
 				map->m_pblk = 0;
 				goto sync_out;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e97b4d8c5efc..3b368bcbc4d7 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -4074,6 +4074,7 @@ void f2fs_end_read_compressed_page(struct page *page, bool failed,
 							block_t blkaddr);
 bool f2fs_cluster_is_empty(struct compress_ctx *cc);
 bool f2fs_cluster_can_merge_page(struct compress_ctx *cc, pgoff_t index);
+bool f2fs_sanity_check_cluster(struct dnode_of_data *dn);
 void f2fs_compress_ctx_add_page(struct compress_ctx *cc, struct page *page);
 int f2fs_write_multi_pages(struct compress_ctx *cc,
 						int *submitted,
-- 
2.22.1