2 files changed, 61 insertions, 0 deletions

diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h
index 94822e74ef73..cb1b2c919963 100644
--- a/fs/ext4/ext4_extents.h
+++ b/fs/ext4/ext4_extents.h
@@ -114,6 +114,17 @@ struct ext4_extent_header {
 
 #define EXT4_EXT_MAGIC          cpu_to_le16(0xf30a)
 
+#define EXT4_EXTENT_TAIL_OFFSET(hdr) \
+        (sizeof(struct ext4_extent_header) + \
+         (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))
+
+static inline struct ext4_extent_tail *
+find_ext4_extent_tail(struct ext4_extent_header *eh)
+{
+        return (struct ext4_extent_tail *)(((void *)eh) +
+                                           EXT4_EXTENT_TAIL_OFFSET(eh));
+}
+
 /*
  * Array of ext4_ext_path contains path to some extent.
  * Creation/lookup routines use it for traversal/splitting/etc.
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 8c1334ee8c7f..6f3b49bd34c7 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -52,6 +52,46 @@
 #define EXT4_EXT_MARK_UNINIT1   0x2  /* mark first half uninitialized */
 #define EXT4_EXT_MARK_UNINIT2   0x4  /* mark second half uninitialized */
 
+static __le32 ext4_extent_block_csum(struct inode *inode,
+                                     struct ext4_extent_header *eh)
+{
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+        __u32 csum;
+
+        csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)eh,
+                           EXT4_EXTENT_TAIL_OFFSET(eh));
+        return cpu_to_le32(csum);
+}
+
+static int ext4_extent_block_csum_verify(struct inode *inode,
+                                         struct ext4_extent_header *eh)
+{
+        struct ext4_extent_tail *et;
+
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+                EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                return 1;
+
+        et = find_ext4_extent_tail(eh);
+        if (et->et_checksum != ext4_extent_block_csum(inode, eh))
+                return 0;
+        return 1;
+}
+
+static void ext4_extent_block_csum_set(struct inode *inode,
+                                       struct ext4_extent_header *eh)
+{
+        struct ext4_extent_tail *et;
+
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
+                EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                return;
+
+        et = find_ext4_extent_tail(eh);
+        et->et_checksum = ext4_extent_block_csum(inode, eh);
+}
+
 static int ext4_split_extent(handle_t *handle,
                                 struct inode *inode,
                                 struct ext4_ext_path *path,
@@ -117,6 +157,7 @@ static int __ext4_ext_dirty(const char *where, unsigned int line,
 {
         int err;
         if (path->p_bh) {
+                ext4_extent_block_csum_set(inode, ext_block_hdr(path->p_bh));
                 /* path points to block */
                 err = __ext4_handle_dirty_metadata(where, line, handle,
                                                    inode, path->p_bh);
@@ -391,6 +432,12 @@ static int __ext4_ext_check(const char *function, unsigned int line,
                 error_msg = "invalid extent entries";
                 goto corrupted;
         }
+        /* Verify checksum on non-root extent tree nodes */
+        if (ext_depth(inode) != depth &&
+            !ext4_extent_block_csum_verify(inode, eh)) {
+                error_msg = "extent tree corrupted";
+                goto corrupted;
+        }
         return 0;
 
 corrupted:
@@ -930,6 +977,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
                 le16_add_cpu(&neh->eh_entries, m);
         }
 
+        ext4_extent_block_csum_set(inode, neh);
         set_buffer_uptodate(bh);
         unlock_buffer(bh);
 
@@ -1008,6 +1056,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
                                 sizeof(struct ext4_extent_idx) * m);
                         le16_add_cpu(&neh->eh_entries, m);
                 }
+                ext4_extent_block_csum_set(inode, neh);
                 set_buffer_uptodate(bh);
                 unlock_buffer(bh);
 
@@ -1105,6 +1154,7 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
         else
                 neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
         neh->eh_magic = EXT4_EXT_MAGIC;
+        ext4_extent_block_csum_set(inode, neh);
         set_buffer_uptodate(bh);
         unlock_buffer(bh);