Re: [PATCH 09/16] udf: create common function for tag checksumming

From: Jan Kara
Date: Thu Jan 10 2008 - 18:19:42 EST

On Thu 10-01-08 23:06:25, marcin.slusarz@xxxxxxxxx wrote:
> Signed-off-by: Marcin Slusarz <marcin.slusarz@xxxxxxxxx>
> CC: Jan Kara <jack@xxxxxxx>
> CC: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Acked-by: Jan Kara <jack@xxxxxxx>

> ---
> fs/udf/inode.c | 15 ++-------------
> fs/udf/misc.c | 35 ++++++++++++++---------------------
> fs/udf/namei.c | 9 +--------
> fs/udf/super.c | 16 ++--------------
> fs/udf/udfdecl.h | 3 +++
> 5 files changed, 22 insertions(+), 56 deletions(-)
>
> diff --git a/fs/udf/inode.c b/fs/udf/inode.c
> index 9adde18..6751945 100644
> --- a/fs/udf/inode.c
> +++ b/fs/udf/inode.c
> @@ -1440,7 +1440,6 @@ static int udf_update_inode(struct inode *inode, int do_sync)
> uint32_t udfperms;
> uint16_t icbflags;
> uint16_t crclen;
> - int i;
> kernel_timestamp cpu_time;
> int err = 0;
> struct udf_sb_info *sbi = UDF_SB(inode->i_sb);
> @@ -1476,12 +1475,7 @@ static int udf_update_inode(struct inode *inode, int do_sync)
> use->descTag.descCRC = cpu_to_le16(udf_crc((char *)use +
> sizeof(tag), crclen,
> 0));
> -
> - use->descTag.tagChecksum = 0;
> - for (i = 0; i < 16; i++)
> - if (i != 4)
> - use->descTag.tagChecksum +=
> - ((uint8_t *)&(use->descTag))[i];
> + use->descTag.tagChecksum = udf_tag_checksum(&use->descTag);
>
> mark_buffer_dirty(bh);
> brelse(bh);
> @@ -1650,12 +1644,7 @@ static int udf_update_inode(struct inode *inode, int do_sync)
> fe->descTag.descCRCLength = cpu_to_le16(crclen);
> fe->descTag.descCRC = cpu_to_le16(udf_crc((char *)fe + sizeof(tag),
> crclen, 0));
> -
> - fe->descTag.tagChecksum = 0;
> - for (i = 0; i < 16; i++)
> - if (i != 4)
> - fe->descTag.tagChecksum +=
> - ((uint8_t *)&(fe->descTag))[i];
> + fe->descTag.tagChecksum = udf_tag_checksum(&fe->descTag);
>
> /* write the data blocks */
> mark_buffer_dirty(bh);
> diff --git a/fs/udf/misc.c b/fs/udf/misc.c
> index a0bf415..585e4ea 100644
> --- a/fs/udf/misc.c
> +++ b/fs/udf/misc.c
> @@ -51,7 +51,6 @@ struct genericFormat *udf_add_extendedattr(struct inode *inode, uint32_t size,
> uint8_t *ea = NULL, *ad = NULL;
> int offset;
> uint16_t crclen;
> - int i;
>
> ea = UDF_I_DATA(inode);
> if (UDF_I_LENEATTR(inode)) {
> @@ -138,11 +137,7 @@ struct genericFormat *udf_add_extendedattr(struct inode *inode, uint32_t size,
> eahd->descTag.descCRCLength = cpu_to_le16(crclen);
> eahd->descTag.descCRC = cpu_to_le16(udf_crc((char *)eahd +
> sizeof(tag), crclen, 0));
> - eahd->descTag.tagChecksum = 0;
> - for (i = 0; i < 16; i++)
> - if (i != 4)
> - eahd->descTag.tagChecksum +=
> - ((uint8_t *)&(eahd->descTag))[i];
> + eahd->descTag.tagChecksum = udf_tag_checksum(&eahd->descTag);
> UDF_I_LENEATTR(inode) += size;
> return (struct genericFormat *)&ea[offset];
> }
> @@ -207,8 +202,6 @@ struct buffer_head *udf_read_tagged(struct super_block *sb, uint32_t block,
> {
> tag *tag_p;
> struct buffer_head *bh = NULL;
> - register uint8_t checksum;
> - register int i;
> struct udf_sb_info *sbi = UDF_SB(sb);
>
> /* Read the block */
> @@ -234,12 +227,7 @@ struct buffer_head *udf_read_tagged(struct super_block *sb, uint32_t block,
> }
>
> /* Verify the tag checksum */
> - checksum = 0U;
> - for (i = 0; i < 4; i++)
> - checksum += (uint8_t)(bh->b_data[i]);
> - for (i = 5; i < 16; i++)
> - checksum += (uint8_t)(bh->b_data[i]);
> - if (checksum != tag_p->tagChecksum) {
> + if (udf_tag_checksum(tag_p) != tag_p->tagChecksum) {
> printk(KERN_ERR "udf: tag checksum failed block %d\n", block);
> goto error_out;
> }
> @@ -277,17 +265,11 @@ struct buffer_head *udf_read_ptagged(struct super_block *sb, kernel_lb_addr loc,
> void udf_update_tag(char *data, int length)
> {
> tag *tptr = (tag *)data;
> - int i;
> -
> length -= sizeof(tag);
>
> - tptr->tagChecksum = 0;
> tptr->descCRCLength = cpu_to_le16(length);
> tptr->descCRC = cpu_to_le16(udf_crc(data + sizeof(tag), length, 0));
> -
> - for (i = 0; i < 16; i++)
> - if (i != 4)
> - tptr->tagChecksum += (uint8_t)(data[i]);
> + tptr->tagChecksum = udf_tag_checksum(tptr);
> }
>
> void udf_new_tag(char *data, uint16_t ident, uint16_t version, uint16_t snum,
> @@ -300,3 +282,14 @@ void udf_new_tag(char *data, uint16_t ident, uint16_t version, uint16_t snum,
> tptr->tagLocation = cpu_to_le32(loc);
> udf_update_tag(data, length);
> }
> +
> +u8 udf_tag_checksum(const tag *t)
> +{
> + u8 *data = (u8 *)t;
> + u8 checksum = 0;
> + int i;
> + for (i = 0; i < sizeof(tag); ++i)
> + if (i != 4) /* position of checksum */
> + checksum += data[i];
> + return checksum;
> +}
> diff --git a/fs/udf/namei.c b/fs/udf/namei.c
> index 25d518b..f1cf18f 100644
> --- a/fs/udf/namei.c
> +++ b/fs/udf/namei.c
> @@ -47,8 +47,6 @@ int udf_write_fi(struct inode *inode, struct fileIdentDesc *cfi,
> {
> uint16_t crclen = fibh->eoffset - fibh->soffset - sizeof(tag);
> uint16_t crc;
> - uint8_t checksum = 0;
> - int i;
> int offset;
> uint16_t liu = le16_to_cpu(cfi->lengthOfImpUse);
> uint8_t lfi = cfi->lengthFileIdent;
> @@ -122,13 +120,8 @@ int udf_write_fi(struct inode *inode, struct fileIdentDesc *cfi,
>
> cfi->descTag.descCRC = cpu_to_le16(crc);
> cfi->descTag.descCRCLength = cpu_to_le16(crclen);
> + cfi->descTag.tagChecksum = udf_tag_checksum(&cfi->descTag);
>
> - for (i = 0; i < 16; i++) {
> - if (i != 4)
> - checksum += ((uint8_t *)&cfi->descTag)[i];
> - }
> -
> - cfi->descTag.tagChecksum = checksum;
> if (adinicb || (sizeof(struct fileIdentDesc) <= -fibh->soffset)) {
> memcpy((uint8_t *)sfi, (uint8_t *)cfi,
> sizeof(struct fileIdentDesc));
> diff --git a/fs/udf/super.c b/fs/udf/super.c
> index 7f75a94..12fb91d 100644
> --- a/fs/udf/super.c
> +++ b/fs/udf/super.c
> @@ -1564,7 +1564,6 @@ static void udf_open_lvid(struct super_block *sb)
> struct udf_sb_info *sbi = UDF_SB(sb);
> struct buffer_head *bh = sbi->s_lvid_bh;
> if (bh) {
> - int i;
> kernel_timestamp cpu_time;
> struct logicalVolIntegrityDesc *lvid =
> (struct logicalVolIntegrityDesc *)bh->b_data;
> @@ -1582,12 +1581,7 @@ static void udf_open_lvid(struct super_block *sb)
> le16_to_cpu(lvid->descTag.descCRCLength),
> 0));
>
> - lvid->descTag.tagChecksum = 0;
> - for (i = 0; i < 16; i++)
> - if (i != 4)
> - lvid->descTag.tagChecksum +=
> - ((uint8_t *) &(lvid->descTag))[i];
> -
> + lvid->descTag.tagChecksum = udf_tag_checksum(&lvid->descTag);
> mark_buffer_dirty(bh);
> }
> }
> @@ -1595,7 +1589,6 @@ static void udf_open_lvid(struct super_block *sb)
> static void udf_close_lvid(struct super_block *sb)
> {
> kernel_timestamp cpu_time;
> - int i;
> struct udf_sb_info *sbi = UDF_SB(sb);
> struct buffer_head *bh = sbi->s_lvid_bh;
> struct logicalVolIntegrityDesc *lvid;
> @@ -1626,12 +1619,7 @@ static void udf_close_lvid(struct super_block *sb)
> le16_to_cpu(lvid->descTag.descCRCLength),
> 0));
>
> - lvid->descTag.tagChecksum = 0;
> - for (i = 0; i < 16; i++)
> - if (i != 4)
> - lvid->descTag.tagChecksum +=
> - ((uint8_t *)&(lvid->descTag))[i];
> -
> + lvid->descTag.tagChecksum = udf_tag_checksum(&lvid->descTag);
> mark_buffer_dirty(bh);
> }
> }
> diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
> index b17ca67..005e3ad 100644
> --- a/fs/udf/udfdecl.h
> +++ b/fs/udf/udfdecl.h
> @@ -36,6 +36,9 @@
>
> #define udf_get_lb_pblock(sb,loc,offset) udf_get_pblock((sb), (loc).logicalBlockNum, (loc).partitionReferenceNum, (offset))
>
> +/* computes tag checksum */
> +u8 udf_tag_checksum(const tag *t);
> +
> struct dentry;
> struct inode;
> struct task_struct;

Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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