Hi!
Here it is. With crc loop device, you can no longer get silent data
corruption due to disk subsystem...
Pavel
--- clean/drivers/block/loop.c Mon Jan 8 22:49:50 2001
+++ linux/drivers/block/loop.c Mon Jan 8 22:44:09 2001
@@ -61,6 +61,7 @@
#include <linux/devfs_fs_kernel.h>
#include <asm/uaccess.h>
+#include <asm/checksum.h>
#include <linux/loop.h>
@@ -118,6 +119,101 @@
return 0;
}
+#define ID printk(KERN_ERR "crc: info about (%s, %d, %d) ", kdevname(lo->lo_device),
+real_block, blksize);
+
+
+static int transfer_crc(struct loop_device *lo, int cmd, char *raw_buf,
+ char *loop_buf, int size, int real_block)
+{
+ struct buffer_head *bh;
+ int blksize = 1024, nsect; /* Size of block on auxilary media */
+ int cksum;
+ u32 *data;
+ nsect = blksize / 4;
+
+ if (!lo->second_device) {
+ ID; printk( "reading from not-yet-setup crc device can result in
+armagedon. Dont try again.\n" );
+ return -1;
+ }
+ bh = getblk(lo->second_device, 1+real_block/nsect, blksize);
+ if (!bh) {
+ ID; printk( "getblk returned NULL.\n" );
+ return -1;
+ }
+ if (!buffer_uptodate(bh)) {
+ ll_rw_block(READ, 1, &bh);
+ wait_on_buffer(bh);
+ if (!buffer_uptodate(bh)) {
+ ID; printk( "could not read block with CRC\n" );
+ goto error;
+ }
+ }
+
+ data = (u32 *) bh->b_data;
+ if (cmd == READ)
+ cksum = csum_partial_copy_nocheck(raw_buf, loop_buf, size, 0);
+ else
+ cksum = csum_partial_copy_nocheck(loop_buf, raw_buf, size, 0);
+
+ if (cmd == READ) {
+ if (le32_to_cpu(data[real_block%nsect]) != cksum) {
+ if (lo->lo_encrypt_key_size == 0) { /* Normal mode */
+ ID; printk( "wrong checksum reading, is %x, should be
+%x\n", cksum, 0x1234 );
+ goto error;
+ } else {
+ ID; printk( "wrong checksum repairing, setting to
+%x\n", cksum );
+ goto repair;
+ }
+ }
+ } else {
+ repair:
+ data[real_block%nsect] = cpu_to_le32(cksum);
+ mark_buffer_uptodate(bh, 1);
+ mark_buffer_dirty(bh);
+ }
+
+ brelse(bh);
+ return 0;
+error:
+ brelse(bh);
+ return -1;
+
+}
+
+static int ioctl_crc(struct loop_device *lo, int cmd, unsigned long arg)
+{
+ struct file *file;
+ struct inode *inode;
+ int error;
+
+ printk( "Entering ioctl_crc\n" );
+ if (cmd != LOOP_CRC_SET_FD)
+ return -EINVAL;
+
+ error = -EBADF;
+ file = fget(arg);
+ if (!file)
+ return -EINVAL;
+
+ error = -EINVAL;
+ inode = file->f_dentry->d_inode;
+ if (!inode) {
+ printk(KERN_ERR "ioctl_crc: NULL inode?!?\n");
+ goto out;
+ }
+
+ if (S_ISBLK(inode->i_mode)) {
+ error = blkdev_open(inode, file);
+ lo->second_device = inode->i_rdev;
+ printk( "loop_crc: Registered device %x\n", lo->second_device );
+ return error;
+ } else {
+ out:
+ fput(file);
+ return -EINVAL;
+ }
+}
+
static int none_status(struct loop_device *lo, struct loop_info *info)
{
return 0;
@@ -142,10 +238,19 @@
init: xor_status
};
+struct loop_func_table crc_funcs = {
+ number: LO_CRYPT_CRC,
+ transfer: transfer_crc,
+ init: none_status,
+ ioctl: ioctl_crc
+};
+
/* xfer_funcs[0] is special - its release function is never called */
struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
&none_funcs,
- &xor_funcs
+ &xor_funcs,
+ NULL, NULL, NULL, NULL, NULL,
+ &crc_funcs,
};
#define MAX_DISK_SIZE 1024*1024*1024
@@ -551,6 +656,7 @@
lo->transfer = NULL;
lo->ioctl = NULL;
lo->lo_device = 0;
+ lo->second_device = 0;
lo->lo_encrypt_type = 0;
lo->lo_offset = 0;
lo->lo_encrypt_key_size = 0;
--- clean/include/linux/loop.h Mon Nov 23 06:29:54 1998
+++ linux/include/linux/loop.h Sat Apr 15 13:22:57 2000
@@ -22,6 +22,7 @@
struct dentry *lo_dentry;
int lo_refcnt;
kdev_t lo_device;
+ kdev_t second_device;
int lo_offset;
int lo_encrypt_type;
int lo_encrypt_key_size;
@@ -94,6 +95,7 @@
#define LO_CRYPT_BLOW 4
#define LO_CRYPT_CAST128 5
#define LO_CRYPT_IDEA 6
+#define LO_CRYPT_CRC 7
#define LO_CRYPT_DUMMY 9
#define LO_CRYPT_SKIPJACK 10
#define MAX_LO_CRYPT 20
@@ -126,5 +128,6 @@
#define LOOP_CLR_FD 0x4C01
#define LOOP_SET_STATUS 0x4C02
#define LOOP_GET_STATUS 0x4C03
+#define LOOP_CRC_SET_FD 0x4C04
#endif
--
I'm [EMAIL PROTECTED] "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at [EMAIL PROTECTED]
----- End forwarded message -----
--
I'm [EMAIL PROTECTED] "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at [EMAIL PROTECTED]
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