[PATCH v2 7/8] makedumpfile: Add erased information in compressed kdump file

[Ken'ichi Ohmichi]

Hi Mahesh,

On Wed, 18 May 2011 01:36:17 +0530
Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com> wrote:
> @@ -9452,6 +9747,7 @@ reassemble_kdump_pages(void)
>  	struct cache_data cd_pd, cd_data;
>  	struct timeval tv_start;
>  	char *data = NULL;
> +	unsigned long data_buf_size = info->page_size;
>  
>  	initialize_2nd_bitmap(&bitmap2);
>  
> @@ -9465,7 +9761,7 @@ reassemble_kdump_pages(void)
>  		free_cache_data(&cd_pd);
>  		return FALSE;
>  	}
> -	if ((data = malloc(info->page_size)) == NULL) {
> +	if ((data = malloc(data_buf_size)) == NULL) {
>  		ERRMSG("Can't allcate memory for page data.\n");
>  		free_cache_data(&cd_pd);
>  		free_cache_data(&cd_data);
> @@ -9570,6 +9866,49 @@ reassemble_kdump_pages(void)
>  	if (!write_cache_bufsz(&cd_data))
>  		goto out;
>  
> +	info->offset_eraseinfo = cd_data.offset;
> +	/* Copy eraseinfo from split dumpfiles to o/p dumpfile */
> +	for (i = 0; i < info->num_dumpfile; i++) {
> +		if (!SPLITTING_SIZE_EI(i))
> +			continue;
> +
> +		if (SPLITTING_SIZE_EI(i) > data_buf_size) {
> +			data_buf_size = SPLITTING_SIZE_EI(i);
> +			if ((data = realloc(data, data_buf_size)) == NULL) {
> +				ERRMSG("Can't allcate memory for eraseinfo"
> +					" data.\n");
> +				goto out;
> +			}
> +		}
> +		if ((fd = open(SPLITTING_DUMPFILE(i), O_RDONLY)) < 0) {
> +			ERRMSG("Can't open a file(%s). %s\n",
> +			    SPLITTING_DUMPFILE(i), strerror(errno));
> +			goto out;
> +		}
> +		if (lseek(fd, SPLITTING_OFFSET_EI(i), SEEK_SET) < 0) {
> +			ERRMSG("Can't seek a file(%s). %s\n",
> +			    SPLITTING_DUMPFILE(i), strerror(errno));
> +			goto out;
> +		}
> +		if (read(fd, data, SPLITTING_SIZE_EI(i)) !=
> +						SPLITTING_SIZE_EI(i)) {
> +			ERRMSG("Can't read a file(%s). %s\n",
> +			    SPLITTING_DUMPFILE(i), strerror(errno));
> +			goto out;
> +		}
> +		if (!write_cache(&cd_data, data, SPLITTING_SIZE_EI(i)))
> +			goto out;
> +		info->size_eraseinfo += SPLITTING_SIZE_EI(i);
> +
> +		close(fd);
> +		fd = 0;
> +	}
> +	if (!write_cache_bufsz(&cd_data))
> +		goto out;
> +
> +	if (!update_sub_header())
> +		goto out;

The above update_sub_header() breaks "--reassemble" option if a dumpfile
does not contain eraseinfo data :

---
# makedumpfile --split -d30 vmcore dump.1 dump.2
Copying data                       : [100 %]
Copying data                       : [100 %]

The dumpfiles are saved to dump.1, and dump.2.

makedumpfile Completed.
# makedumpfile --reassemble dump.1 dump.2 dump.3
Copying data                       : [100 %]
The dumpfile is saved to dump.3.

makedumpfile Completed.
# crash vmlinux dump.3
[..]

crash: page excluded: kernel virtual address: ffffffff8040b220  type: "cpu_possible_mask"
#
---

The cause is that info->sub_header, which is written in update_sub_header(),
is filled with 0x0.
The following change fixes this problem:

---
@@ -9378,6 +9680,7 @@ reassemble_kdump_header(void)
                    info->name_dumpfile, strerror(errno));
                return FALSE;
        }
+       memcpy(&info->sub_header, &kh, sizeof(kh));

        /*
         * Write dump bitmap to both a dumpfile and a bitmap file.
---

Thanks
Ken'ichi Ohmichi