Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull Ext4 updates from Theodore Ts'o:
 "The major new feature added in this update is Darrick J Wong's
  metadata checksum feature, which adds crc32 checksums to ext4's
  metadata fields.

  There is also the usual set of cleanups and bug fixes."

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (44 commits)
  ext4: hole-punch use truncate_pagecache_range
  jbd2: use kmem_cache_zalloc wrapper instead of flag
  ext4: remove mb_groups before tearing down the buddy_cache
  ext4: add ext4_mb_unload_buddy in the error path
  ext4: don't trash state flags in EXT4_IOC_SETFLAGS
  ext4: let getattr report the right blocks in delalloc+bigalloc
  ext4: add missing save_error_info() to ext4_error()
  ext4: add debugging trigger for ext4_error()
  ext4: protect group inode free counting with group lock
  ext4: use consistent ssize_t type in ext4_file_write()
  ext4: fix format flag in ext4_ext_binsearch_idx()
  ext4: cleanup in ext4_discard_allocated_blocks()
  ext4: return ENOMEM when mounts fail due to lack of memory
  ext4: remove redundundant "(char *) bh->b_data" casts
  ext4: disallow hard-linked directory in ext4_lookup
  ext4: fix potential integer overflow in alloc_flex_gd()
  ext4: remove needs_recovery in ext4_mb_init()
  ext4: force ro mount if ext4_setup_super() fails
  ext4: fix potential NULL dereference in ext4_free_inodes_counts()
  ext4/jbd2: add metadata checksumming to the list of supported features
  ...

1 files changed, 39 insertions, 5 deletions

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index ed6548d89165..f99a1311e847 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -6,12 +6,45 @@
 
 #include "ext4.h"
 
+/* Checksumming functions */
+static __u32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	int offset = offsetof(struct mmp_struct, mmp_checksum);
+	__u32 csum;
+
+	csum = ext4_chksum(sbi, sbi->s_csum_seed, (char *)mmp, offset);
+
+	return cpu_to_le32(csum);
+}
+
+int ext4_mmp_csum_verify(struct super_block *sb, struct mmp_struct *mmp)
+{
+	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+				       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return 1;
+
+	return mmp->mmp_checksum == ext4_mmp_csum(sb, mmp);
+}
+
+void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp)
+{
+	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
+				       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return;
+
+	mmp->mmp_checksum = ext4_mmp_csum(sb, mmp);
+}
+
 /*
  * Write the MMP block using WRITE_SYNC to try to get the block on-disk
  * faster.
  */
-static int write_mmp_block(struct buffer_head *bh)
+static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
 {
+	struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
+
+	ext4_mmp_csum_set(sb, mmp);
 	mark_buffer_dirty(bh);
 	lock_buffer(bh);
 	bh->b_end_io = end_buffer_write_sync;
@@ -59,7 +92,8 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
 	}
 
 	mmp = (struct mmp_struct *)((*bh)->b_data);
-	if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC)
+	if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC ||
+	    !ext4_mmp_csum_verify(sb, mmp))
 		return -EINVAL;
 
 	return 0;
@@ -120,7 +154,7 @@ static int kmmpd(void *data)
 		mmp->mmp_time = cpu_to_le64(get_seconds());
 		last_update_time = jiffies;
 
-		retval = write_mmp_block(bh);
+		retval = write_mmp_block(sb, bh);
 		/*
 		 * Don't spew too many error messages. Print one every
 		 * (s_mmp_update_interval * 60) seconds.
@@ -200,7 +234,7 @@ static int kmmpd(void *data)
 	mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
 	mmp->mmp_time = cpu_to_le64(get_seconds());
 
-	retval = write_mmp_block(bh);
+	retval = write_mmp_block(sb, bh);
 
 failed:
 	kfree(data);
@@ -299,7 +333,7 @@ skip:
 	seq = mmp_new_seq();
 	mmp->mmp_seq = cpu_to_le32(seq);
 
-	retval = write_mmp_block(bh);
+	retval = write_mmp_block(sb, bh);
 	if (retval)
 		goto failed;