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    Subject[PATCH 1/2] ext4: Calculate and verify inode checksums
    This patch introduces to ext4 the ability to calculate and verify inode
    checksums. This requires the use of a new ro compatibility flag and some
    accompanying e2fsprogs patches to provide the relevant features in tune2fs and
    e2fsck.

    Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
    ---

    fs/ext4/ext4.h | 6 ++++--
    fs/ext4/inode.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++-
    2 files changed, 55 insertions(+), 3 deletions(-)

    diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
    index 4daaf2b..8815928 100644
    --- a/fs/ext4/ext4.h
    +++ b/fs/ext4/ext4.h
    @@ -617,7 +617,7 @@ struct ext4_inode {
    } masix2;
    } osd2; /* OS dependent 2 */
    __le16 i_extra_isize;
    - __le16 i_pad1;
    + __le16 i_checksum; /* crc16(sb_uuid+inodenum+inode) */
    __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) */
    @@ -1338,6 +1338,7 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
    #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010
    #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK 0x0020
    #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE 0x0040
    +#define EXT4_FEATURE_RO_COMPAT_INODE_CSUM 0x0400

    #define EXT4_FEATURE_INCOMPAT_COMPRESSION 0x0001
    #define EXT4_FEATURE_INCOMPAT_FILETYPE 0x0002
    @@ -1364,7 +1365,8 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
    EXT4_FEATURE_RO_COMPAT_DIR_NLINK | \
    EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE | \
    EXT4_FEATURE_RO_COMPAT_BTREE_DIR |\
    - EXT4_FEATURE_RO_COMPAT_HUGE_FILE)
    + EXT4_FEATURE_RO_COMPAT_HUGE_FILE |\
    + EXT4_FEATURE_RO_COMPAT_INODE_CSUM)

    /*
    * Default values for user and/or group using reserved blocks
    diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
    index 1a86282..dc76f19 100644
    --- a/fs/ext4/inode.c
    +++ b/fs/ext4/inode.c
    @@ -42,6 +42,7 @@
    #include <linux/printk.h>
    #include <linux/slab.h>
    #include <linux/ratelimit.h>
    +#include <linux/crc16.h>

    #include "ext4_jbd2.h"
    #include "xattr.h"
    @@ -52,6 +53,40 @@

    #define MPAGE_DA_EXTENT_TAIL 0x01

    +static __le16 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw)
    +{
    + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
    + struct ext4_inode_info *ei = EXT4_I(inode);
    + int offset = offsetof(struct ext4_inode, i_checksum);
    + __le32 inum = cpu_to_le32(inode->i_ino);
    + __u16 crc = 0;
    +
    + if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
    + EXT4_FEATURE_RO_COMPAT_INODE_CSUM) &&
    + le16_to_cpu(raw->i_extra_isize) >= 4) {
    + crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));
    + crc = crc16(crc, (__u8 *)&inum, sizeof(inum));
    + crc = crc16(crc, (__u8 *)raw, offset);
    + offset += sizeof(raw->i_checksum); /* skip checksum */
    + /* for checksum of struct ext4_inode do the rest...*/
    + if (ei->i_extra_isize > 4)
    + crc = crc16(crc, (__u8 *)raw + offset,
    + ei->i_extra_isize - 4);
    + }
    +
    + return cpu_to_le16(crc);
    +}
    +
    +static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw)
    +{
    + if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
    + EXT4_FEATURE_RO_COMPAT_INODE_CSUM) &&
    + (raw->i_checksum != ext4_inode_csum(inode, raw)))
    + return 0;
    +
    + return 1;
    +}
    +
    static inline int ext4_begin_ordered_truncate(struct inode *inode,
    loff_t new_size)
    {
    @@ -4802,7 +4837,8 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
    struct ext4_inode *raw_inode;
    struct ext4_inode_info *ei;
    struct inode *inode;
    - journal_t *journal = EXT4_SB(sb)->s_journal;
    + struct ext4_sb_info *sbi = EXT4_SB(sb);
    + journal_t *journal = sbi->s_journal;
    long ret;
    int block;

    @@ -4916,6 +4952,14 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
    } else
    ei->i_extra_isize = 0;

    + if (!ext4_inode_csum_verify(inode, raw_inode)) {
    + EXT4_ERROR_INODE(inode, "checksum invalid (%u != %u)",
    + le16_to_cpu(ext4_inode_csum(inode, raw_inode)),
    + le16_to_cpu(raw_inode->i_checksum));
    + ret = -EIO;
    + goto bad_inode;
    + }
    +
    EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
    EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
    EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
    @@ -5138,6 +5182,12 @@ static int ext4_do_update_inode(handle_t *handle,
    raw_inode->i_version_hi =
    cpu_to_le32(inode->i_version >> 32);
    raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
    +
    + if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
    + EXT4_FEATURE_RO_COMPAT_INODE_CSUM) &&
    + EXT4_FITS_IN_INODE(raw_inode, ei, i_checksum))
    + raw_inode->i_checksum =
    + ext4_inode_csum(inode, raw_inode);
    }

    BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");

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      Last update: 2011-04-07 22:59    [W:0.046 / U:119.004 seconds]
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