ext4: change on-disk layout to support extended metadata checksumming

Define flags and change structure definitions to allow checksumming of
ext4 metadata.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0e01e90add8bc42f1492a73a2e1e78331b8ae134..61dd739b64f068352bc6bfd3461851811c0f236f 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -298,7 +298,9 @@ struct ext4_group_desc
        __le16  bg_free_inodes_count_lo;/* Free inodes count */
        __le16  bg_used_dirs_count_lo;  /* Directories count */
        __le16  bg_flags;               /* EXT4_BG_flags (INODE_UNINIT, etc) */
-       __u32   bg_reserved[2];         /* Likely block/inode bitmap checksum */
+       __le32  bg_exclude_bitmap_lo;   /* Exclude bitmap for snapshots */
+       __le16  bg_block_bitmap_csum_lo;/* crc32c(s_uuid+grp_num+bbitmap) LE */
+       __le16  bg_inode_bitmap_csum_lo;/* crc32c(s_uuid+grp_num+ibitmap) LE */
        __le16  bg_itable_unused_lo;    /* Unused inodes count */
        __le16  bg_checksum;            /* crc16(sb_uuid+group+desc) */
        __le32  bg_block_bitmap_hi;     /* Blocks bitmap block MSB */
@@ -308,7 +310,10 @@ struct ext4_group_desc
        __le16  bg_free_inodes_count_hi;/* Free inodes count MSB */
        __le16  bg_used_dirs_count_hi;  /* Directories count MSB */
        __le16  bg_itable_unused_hi;    /* Unused inodes count MSB */
-       __u32   bg_reserved2[3];
+       __le32  bg_exclude_bitmap_hi;   /* Exclude bitmap block MSB */
+       __le16  bg_block_bitmap_csum_hi;/* crc32c(s_uuid+grp_num+bbitmap) BE */
+       __le16  bg_inode_bitmap_csum_hi;/* crc32c(s_uuid+grp_num+ibitmap) BE */
+       __u32   bg_reserved;
 };
 
 /*
@@ -650,7 +655,8 @@ struct ext4_inode {
                        __le16  l_i_file_acl_high;
                        __le16  l_i_uid_high;   /* these 2 fields */
                        __le16  l_i_gid_high;   /* were reserved2[0] */
-                       __u32   l_i_reserved2;
+                       __le16  l_i_checksum_lo;/* crc32c(uuid+inum+inode) LE */
+                       __le16  l_i_reserved;
                } linux2;
                struct {
                        __le16  h_i_reserved1;  /* Obsoleted fragment number/size which are removed in ext4 */
@@ -666,7 +672,7 @@ struct ext4_inode {
                } masix2;
        } osd2;                         /* OS dependent 2 */
        __le16  i_extra_isize;
-       __le16  i_pad1;
+       __le16  i_checksum_hi;  /* crc32c(uuid+inum+inode) BE */
        __le32  i_ctime_extra;  /* extra Change time      (nsec << 2 | epoch) */
        __le32  i_mtime_extra;  /* extra Modification time(nsec << 2 | epoch) */
        __le32  i_atime_extra;  /* extra Access time      (nsec << 2 | epoch) */
@@ -768,7 +774,7 @@ do {                                                                               \
 #define i_gid_low      i_gid
 #define i_uid_high     osd2.linux2.l_i_uid_high
 #define i_gid_high     osd2.linux2.l_i_gid_high
-#define i_reserved2    osd2.linux2.l_i_reserved2
+#define i_checksum_lo  osd2.linux2.l_i_checksum_lo
 
 #elif defined(__GNU__)
 
@@ -1001,6 +1007,9 @@ extern void ext4_set_bits(void *bm, int cur, int len);
 #define EXT4_ERRORS_PANIC              3       /* Panic */
 #define EXT4_ERRORS_DEFAULT            EXT4_ERRORS_CONTINUE
 
+/* Metadata checksum algorithm codes */
+#define EXT4_CRC32C_CHKSUM             1
+
 /*
  * Structure of the super block
  */
@@ -1087,7 +1096,7 @@ struct ext4_super_block {
        __le64  s_mmp_block;            /* Block for multi-mount protection */
        __le32  s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/
        __u8    s_log_groups_per_flex;  /* FLEX_BG group size */
-       __u8    s_reserved_char_pad;
+       __u8    s_checksum_type;        /* metadata checksum algorithm used */
        __le16  s_reserved_pad;
        __le64  s_kbytes_written;       /* nr of lifetime kilobytes written */
        __le32  s_snapshot_inum;        /* Inode number of active snapshot */
@@ -1113,7 +1122,8 @@ struct ext4_super_block {
        __le32  s_usr_quota_inum;       /* inode for tracking user quota */
        __le32  s_grp_quota_inum;       /* inode for tracking group quota */
        __le32  s_overhead_clusters;    /* overhead blocks/clusters in fs */
-       __le32  s_reserved[109];        /* Padding to the end of the block */
+       __le32  s_reserved[108];        /* Padding to the end of the block */
+       __le32  s_checksum;             /* crc32c(superblock) */
 };
 
 #define EXT4_S_ERR_LEN (EXT4_S_ERR_END - EXT4_S_ERR_START)
@@ -1414,6 +1424,12 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
 #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE     0x0040
 #define EXT4_FEATURE_RO_COMPAT_QUOTA           0x0100
 #define EXT4_FEATURE_RO_COMPAT_BIGALLOC                0x0200
+/*
+ * METADATA_CSUM also enables group descriptor checksums (GDT_CSUM).  When
+ * METADATA_CSUM is set, group descriptor checksums use the same algorithm as
+ * all other data structures' checksums.  However, the METADATA_CSUM and
+ * GDT_CSUM bits are mutually exclusive.
+ */
 #define EXT4_FEATURE_RO_COMPAT_METADATA_CSUM   0x0400
 
 #define EXT4_FEATURE_INCOMPAT_COMPRESSION      0x0001
@@ -1526,6 +1542,18 @@ struct ext4_dir_entry_2 {
        char    name[EXT4_NAME_LEN];    /* File name */
 };
 
+/*
+ * This is a bogus directory entry at the end of each leaf block that
+ * records checksums.
+ */
+struct ext4_dir_entry_tail {
+       __le32  det_reserved_zero1;     /* Pretend to be unused */
+       __le16  det_rec_len;            /* 12 */
+       __u8    det_reserved_zero2;     /* Zero name length */
+       __u8    det_reserved_ft;        /* 0xDE, fake file type */
+       __le32  det_checksum;           /* crc32c(uuid+inum+dirblock) */
+};
+
 /*
  * Ext4 directory file types.  Only the low 3 bits are used.  The
  * other bits are reserved for now.
@@ -1541,6 +1569,8 @@ struct ext4_dir_entry_2 {
 
 #define EXT4_FT_MAX            8
 
+#define EXT4_FT_DIR_CSUM       0xDE
+
 /*
  * EXT4_DIR_PAD defines the directory entries boundaries
  *
@@ -1741,7 +1771,8 @@ struct mmp_struct {
        __le16  mmp_check_interval;
 
        __le16  mmp_pad1;
-       __le32  mmp_pad2[227];
+       __le32  mmp_pad2[226];
+       __le32  mmp_checksum;           /* crc32c(uuid+mmp_block) */
 };
 
 /* arguments passed to the mmp thread */

diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h
index 0f58b86e3a0206e19626f361f453aa80b2838857..94822e74ef73bf093331b412afab5bd03d11ebae 100644 (file)
--- a/fs/ext4/ext4_extents.h
+++ b/fs/ext4/ext4_extents.h
@@ -63,8 +63,21 @@
  * ext4_inode has i_block array (60 bytes total).
  * The first 12 bytes store ext4_extent_header;
  * the remainder stores an array of ext4_extent.
+ * For non-inode extent blocks, ext4_extent_tail
+ * follows the array.
  */
 
+/*
+ * This is the extent tail on-disk structure.
+ * All other extent structures are 12 bytes long.  It turns out that
+ * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
+ * covers all valid ext4 block sizes.  Therefore, this tail structure can be
+ * crammed into the end of the block without having to rebalance the tree.
+ */
+struct ext4_extent_tail {
+       __le32  et_checksum;    /* crc32c(uuid+inum+extent_block) */
+};
+
 /*
  * This is the extent on-disk structure.
  * It's used at the bottom of the tree.

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 349d7b3671c863ce1565a5d2a184c6bbdafbf6e3..b58bd5c8ffe72e4c96abc76dd6e0d63de5b72826 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -145,6 +145,14 @@ struct dx_map_entry
        u16 size;
 };
 
+/*
+ * This goes at the end of each htree block.
+ */
+struct dx_tail {
+       u32 dt_reserved;
+       __le32 dt_checksum;     /* crc32c(uuid+inum+dirblock) */
+};
+
 static inline ext4_lblk_t dx_get_block(struct dx_entry *entry);
 static void dx_set_block(struct dx_entry *entry, ext4_lblk_t value);
 static inline unsigned dx_get_hash(struct dx_entry *entry);

diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index 25b7387ff183f880cdb9ccaf2529ca8c0f218a7b..91f31ca7d9af9df24a965c64bb0271c43a4d4b09 100644 (file)
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -27,7 +27,9 @@ struct ext4_xattr_header {
        __le32  h_refcount;     /* reference count */
        __le32  h_blocks;       /* number of disk blocks used */
        __le32  h_hash;         /* hash value of all attributes */
-       __u32   h_reserved[4];  /* zero right now */
+       __le32  h_checksum;     /* crc32c(uuid+id+xattrblock) */
+                               /* id = inum if refcount=1, blknum otherwise */
+       __u32   h_reserved[3];  /* zero right now */
 };
 
 struct ext4_xattr_ibody_header {