I'm trying a small code on a bad scsi disk
and got the output
scsi0: MEDIUM ERROR on channel 0, id 0, lun 0, CDB: Read (6) 13 78 00 02
00
Info fld=0x0, Current sd08:00: sense key Medium Error
scsidisk I/O error: dev 08:00, sector 1275904
blocknr 637952 compl 1 bad
scsi0: MEDIUM ERROR on channel 0, id 0, lun 0, CDB: Read (6) 13 78 00 02
00
Info fld=0x0, Current sd08:00: sense key Medium Error
scsidisk I/O error: dev 08:00, sector 1275904
blocknr 637952 compl 358504 bad
scsi0: MEDIUM ERROR on channel 0, id 0, lun 0, CDB: Read (6) 13 78 00 02
00
Info fld=0x0, Current sd08:00: sense key Medium Error
scsidisk I/O error: dev 08:00, sector 1275904
blocknr 637952 compl 1030955 bad
blocknr = 638976 a block completed
-------------------------------------------------------------------------
What i observed was the buf_end_io function is called multiple times in
case of failure.
I can attribute those multiple messages as scsi retries, but i don't
understand why buf_endio is called multiple times.
regards
mgopi
My code is
int mod_ioctl(struct inode * inode,struct file * filp,unsigned int
cmd,unsigned long arg);
struct file_operations mod_fops = {
NULL,
NULL,
NULL,
NULL,
NULL,
mod_ioctl,
NULL
};
static int mod_major;
int mod_dochk(unsigned long);
int init_module(void){
mod_major = register_chrdev(0,"mod",&mod_fops);
if(mod_major < 0){
printk(KERN_WARNING "mod : can't register\n");
return mod_major;
}
return 0;
}
void cleanup_module(void)
{
unregister_chrdev(mod_major,"mod");
}
int mod_ioctl (struct inode * inode,struct file * filp,unsigned int
cmd,unsigned long arg)
{
switch(cmd) {
case MOD_CHK:
if(access_ok(VERIFY_READ,arg,sizeof(int)) <
0) return -1;
return mod_dochk(arg);
default:
return -EINVAL;
}
}
static volatile atomic_t completed;
struct wait_queue * wq = NULL;
static void buf_endio(struct buffer_head * bh,int uptodate)
{
mark_buffer_uptodate(bh,uptodate);
unlock_buffer(bh);
if(!uptodate)
printk(KERN_ERR"blocknr %ld compl %d
bad\n",bh->b_blocknr,atomic_read(&completed));
/*if(atomic_read(&completed) < 2048)
//printk("%d ",atomic_read(&completed));
//else printk("\n");
;*/
atomic_inc(&completed);
// if(atomic_read(&completed) == 1024)
// wake_up(&wq);
}
int mod_dochk(unsigned long arg)
{
kdev_t dev = MKDEV(8,0);
struct buffer_head ** bufptr = NULL;
int i = 0,j = 0;
int blocknr = 0;
bufptr = (struct buffer_head **) kmalloc(1024 * sizeof(struct
buffer_head *),GFP_KERNEL);
if(bufptr == NULL) return -1;
for(i = 0;i < 1024;i++)
{
bufptr[i] = (struct buffer_head *) kmalloc(sizeof(struct
buffer_head),GFP_KERNEL);
if(bufptr[i] == NULL)
{
printk(KERN_INFO"mod_ioctl:cannot allocate
buffer\n");
for(j = 0;j<i;j++)
kfree(bufptr[j]);
kfree(bufptr);
return -1;
}
memset(bufptr[i],0,sizeof(struct buffer_head));
bufptr[i]->b_data = (char *)kmalloc(1024 *
sizeof(char),GFP_KERNEL);
if(bufptr[i]->b_data == NULL)
{
printk(KERN_INFO"mod_ioctl:cannot allocate
data\n");
for(j = 0;j<i;j++)
{
kfree(bufptr[j]->b_data);
kfree(bufptr[j]);
}
kfree(bufptr);
return -1;
}
init_buffer(bufptr[i],dev,0,buf_endio,0);
bufptr[i]->b_size = 1024;
bufptr[i]->b_state = (1<<BH_Req);
bufptr[i]->b_rdev = dev;
bufptr[i]->b_count = 1;
bufptr[i]->b_list = BUF_LOCKED;
}
j = 0;
//while(j < 1023)
{
//copy_from_user(&blocknr,(int *)arg,sizeof(int));
atomic_set(&completed,0);
get_user(blocknr,(int *)arg);
printk(KERN_ERR"bl = %d\n",blocknr);
for(i = 0;i<1024;i++)
{
bufptr[i]->b_blocknr = blocknr++;
ll_rw_block(READ,1024,bufptr);
if(blocknr % 1024 == 0) break;
}
//if(atomic_read(&completed) <
1024) interruptible_sleep_on(&wq);
for(i = 0;i<1024;i++)
wait_on_buffer(bufptr[i]);
printk(KERN_ERR"blocknr = %d a block
completed\n",blocknr);
// j++;
}
for(j=0;j<1024;j++)
{
kfree(bufptr[j]->b_data);
kfree(bufptr[j]);
}
kfree(bufptr);
return 0;
}
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