7 files changed, 76 insertions, 7 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f19192bde094..5adbce519b66 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1280,6 +1280,9 @@ struct ext4_sb_info {
 
         /* Reference to checksum algorithm driver via cryptoapi */
         struct crypto_shash *s_chksum_driver;
+
+        /* Precomputed FS UUID checksum for seeding other checksums */
+        __u32 s_csum_seed;
 };
 
 static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
@@ -2004,6 +2007,10 @@ extern int ext4_group_extend(struct super_block *sb,
 extern int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count);
 
 /* super.c */
+extern int ext4_superblock_csum_verify(struct super_block *sb,
+                                       struct ext4_super_block *es);
+extern void ext4_superblock_csum_set(struct super_block *sb,
+                                     struct ext4_super_block *es);
 extern void *ext4_kvmalloc(size_t size, gfp_t flags);
 extern void *ext4_kvzalloc(size_t size, gfp_t flags);
 extern void ext4_kvfree(void *ptr);
@@ -2279,6 +2286,9 @@ static inline void ext4_unlock_group(struct super_block *sb,
 
 static inline void ext4_mark_super_dirty(struct super_block *sb)
 {
+        struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+
+        ext4_superblock_csum_set(sb, es);
         if (EXT4_SB(sb)->s_journal == NULL)
                 sb->s_dirt =1;
 }
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index aca179017582..90f7c2e84db1 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -138,16 +138,23 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line,
 }
 
 int __ext4_handle_dirty_super(const char *where, unsigned int line,
-                              handle_t *handle, struct super_block *sb)
+                              handle_t *handle, struct super_block *sb,
+                              int now)
 {
         struct buffer_head *bh = EXT4_SB(sb)->s_sbh;
         int err = 0;
 
         if (ext4_handle_valid(handle)) {
+                ext4_superblock_csum_set(sb,
+                                (struct ext4_super_block *)bh->b_data);
                 err = jbd2_journal_dirty_metadata(handle, bh);
                 if (err)
                         ext4_journal_abort_handle(where, line, __func__,
                                                   bh, handle, err);
+        } else if (now) {
+                ext4_superblock_csum_set(sb,
+                                (struct ext4_super_block *)bh->b_data);
+                mark_buffer_dirty(bh);
         } else
                 sb->s_dirt = 1;
         return err;
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 83b20fcf9400..f440e8f1841f 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -213,7 +213,8 @@ int __ext4_handle_dirty_metadata(const char *where, unsigned int line,
                                  struct buffer_head *bh);
 
 int __ext4_handle_dirty_super(const char *where, unsigned int line,
-                              handle_t *handle, struct super_block *sb);
+                              handle_t *handle, struct super_block *sb,
+                              int now);
 
 #define ext4_journal_get_write_access(handle, bh) \
         __ext4_journal_get_write_access(__func__, __LINE__, (handle), (bh))
@@ -225,8 +226,10 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
 #define ext4_handle_dirty_metadata(handle, inode, bh) \
         __ext4_handle_dirty_metadata(__func__, __LINE__, (handle), (inode), \
                                      (bh))
+#define ext4_handle_dirty_super_now(handle, sb) \
+        __ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb), 1)
 #define ext4_handle_dirty_super(handle, sb) \
-        __ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb))
+        __ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb), 0)
 
 handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
 int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c77b0bd2c711..8bc21ecc1df5 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3936,7 +3936,7 @@ static int ext4_do_update_inode(handle_t *handle,
                         EXT4_SET_RO_COMPAT_FEATURE(sb,
                                         EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
                         ext4_handle_sync(handle);
-                        err = ext4_handle_dirty_super(handle, sb);
+                        err = ext4_handle_dirty_super_now(handle, sb);
                 }
         }
         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index b58bd5c8ffe7..625125172d05 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2021,7 +2021,7 @@ int ext4_orphan_add(handle_t *handle, struct inode *inode)
         /* Insert this inode at the head of the on-disk orphan list... */
         NEXT_ORPHAN(inode) = le32_to_cpu(EXT4_SB(sb)->s_es->s_last_orphan);
         EXT4_SB(sb)->s_es->s_last_orphan = cpu_to_le32(inode->i_ino);
-        err = ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
+        err = ext4_handle_dirty_super_now(handle, sb);
         rc = ext4_mark_iloc_dirty(handle, inode, &iloc);
         if (!err)
                 err = rc;
@@ -2094,7 +2094,7 @@ int ext4_orphan_del(handle_t *handle, struct inode *inode)
                 if (err)
                         goto out_brelse;
                 sbi->s_es->s_last_orphan = cpu_to_le32(ino_next);
-                err = ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
+                err = ext4_handle_dirty_super_now(handle, inode->i_sb);
         } else {
                 struct ext4_iloc iloc2;
                 struct inode *i_prev =
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 59fa0be27251..e0374757a94b 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -796,7 +796,7 @@ static int add_new_gdb(handle_t *handle, struct inode *inode,
         ext4_kvfree(o_group_desc);
 
         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
-        err = ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
+        err = ext4_handle_dirty_super_now(handle, sb);
         if (err)
                 ext4_std_error(sb, err);
 
@@ -968,6 +968,8 @@ static void update_backups(struct super_block *sb,
                 goto exit_err;
         }
 
+        ext4_superblock_csum_set(sb, (struct ext4_super_block *)data);
+
         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
                 struct buffer_head *bh;
 
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 11a0a7078da7..f80c7e612829 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -122,6 +122,38 @@ static int ext4_verify_csum_type(struct super_block *sb,
         return es->s_checksum_type == EXT4_CRC32C_CHKSUM;
 }
 
+static __le32 ext4_superblock_csum(struct super_block *sb,
+                                   struct ext4_super_block *es)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(sb);
+        int offset = offsetof(struct ext4_super_block, s_checksum);
+        __u32 csum;
+
+        csum = ext4_chksum(sbi, ~0, (char *)es, offset);
+
+        return cpu_to_le32(csum);
+}
+
+int ext4_superblock_csum_verify(struct super_block *sb,
+                                struct ext4_super_block *es)
+{
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                return 1;
+
+        return es->s_checksum == ext4_superblock_csum(sb, es);
+}
+
+void ext4_superblock_csum_set(struct super_block *sb,
+                              struct ext4_super_block *es)
+{
+        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                return;
+
+        es->s_checksum = ext4_superblock_csum(sb, es);
+}
+
 void *ext4_kvmalloc(size_t size, gfp_t flags)
 {
         void *ret;
@@ -3057,6 +3089,20 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                 }
         }
 
+        /* Check superblock checksum */
+        if (!ext4_superblock_csum_verify(sb, es)) {
+                ext4_msg(sb, KERN_ERR, "VFS: Found ext4 filesystem with "
+                         "invalid superblock checksum.  Run e2fsck?");
+                silent = 1;
+                goto cantfind_ext4;
+        }
+
+        /* Precompute checksum seed for all metadata */
+        if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                        EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+                sbi->s_csum_seed = ext4_chksum(sbi, ~0, es->s_uuid,
+                                               sizeof(es->s_uuid));
+
         /* Set defaults before we parse the mount options */
         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
         set_opt(sb, INIT_INODE_TABLE);
@@ -4059,6 +4105,7 @@ static int ext4_commit_super(struct super_block *sb, int sync)
                                 &EXT4_SB(sb)->s_freeinodes_counter));
         sb->s_dirt = 0;
         BUFFER_TRACE(sbh, "marking dirty");
+        ext4_superblock_csum_set(sb, es);
         mark_buffer_dirty(sbh);
         if (sync) {
                 error = sync_dirty_buffer(sbh);