On 04/06/2011 03:45 PM, Darrick J. Wong wrote:
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@xxxxxxxxxx> --- 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");
You may want to look into jbd2 buffer triggers. struct jbd2_buffer_trigger_type Instead of computing checksum on every update, it allows one to compute it just before the journal write. More efficient. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html