Messages in this thread Patch in this message | | | Date | Sat, 29 Mar 2008 23:30:06 -0400 | From | Bob Copeland <> | Subject | Re: [PATCH 6/7] omfs: add checksumming routines |
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Version 2 of this patch, with changes: - use lib/crc-itu-t.c instead of open-coded version
From 6ce3bb9ce2faaf937df0ec8e64c39e1adc403b2e Mon Sep 17 00:00:00 2001 From: Bob Copeland <me@bobcopeland.com> Date: Thu, 27 Mar 2008 17:23:12 -0400 Subject: [PATCH] omfs: add checksumming routines
OMFS checksums the metadata of all filesystem objects. This change adds the necessary functions to do so.
Signed-off-by: Bob Copeland <me@bobcopeland.com> --- fs/omfs/checksum.c | 31 +++++++++++++++++++++++++++++++ 1 files changed, 31 insertions(+), 0 deletions(-) create mode 100644 fs/omfs/checksum.c
diff --git a/fs/omfs/checksum.c b/fs/omfs/checksum.c new file mode 100644 index 0000000..cbd0471 --- /dev/null +++ b/fs/omfs/checksum.c @@ -0,0 +1,31 @@ +#include <linux/fs.h> +#include <linux/buffer_head.h> +#include <linux/crc-itu-t.h> +#include "omfs.h" + +/* + * Update the header checksums for a dirty inode based on its contents. + * Caller is expected to hold the buffer head underlying oi and mark it + * dirty. + */ +int omfs_update_checksums(struct omfs_inode *oi) +{ + int ret = 0; + int xor, i, ofs = 0, count; + u16 crc = 0; + unsigned char *ptr = (unsigned char *) oi; + + count = be32_to_cpu(oi->i_head.h_body_size); + ofs = sizeof(struct omfs_header); + + crc = crc_itu_t(crc, ptr + ofs, count); + oi->i_head.h_crc = cpu_to_be16(crc); + + xor = ptr[0]; + for (i = 1; i < OMFS_XOR_COUNT; i++) + xor ^= ptr[i]; + + oi->i_head.h_check_xor = xor; + + return ret; +} -- 1.5.4.2.182.gb3092
-- Bob Copeland %% www.bobcopeland.com
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