[Crash-utility] [PATCH v3 5/5] diskdump: Warn on incomplete dumps
crash warns that ELF dump is incomplete like this:
WARNING: vmcore: may be truncated or incomplete
PT_LOAD p_offset: 218960740
p_filesz: 4194304
bytes required: 223155044
dumpfile size: 219960740
The warning saves a lot of time when figuring out what went wrong, but
crash misses explicit dump detection for compressed kdumps.
The change adds the warning for compressed kdumps:
WARNING: vmcore: may be truncated or incomplete
data_offset: 262144
block_size: 65536
total_valid_pages: 2438
first_empty_pd: 100
bytes required: 157467661
dumpfile size: 265982
bytes required is computed as:
data_offset (kdump header + bitmaps)
+
total_valid_pages * page descriptor size (page descriptors)
+
zero page (that immediately follows page descriptors)
+
compressed size of every present page in the list of valid pages
+
block_size for every incomplete page (i.e page descriptor has
zero offset)
The warning is also printed for incomplete split dumps.
Signed-off-by: Roman Bolshakov <r.bolshakov(a)yadro.com>
---
diskdump.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 69 insertions(+), 2 deletions(-)
diff --git a/diskdump.c b/diskdump.c
index de3eeb2..e802d04 100644
--- a/diskdump.c
+++ b/diskdump.c
@@ -23,6 +23,8 @@
* GNU General Public License for more details.
*/
+#define _LARGEFILE64_SOURCE 1 /* stat64() */
+
#include "defs.h"
#include "diskdump.h"
#include "xen_dom0.h"
@@ -548,6 +550,12 @@ read_dump_header(char *file)
ulong pfn;
int i, j, max_sect_len;
int is_split = 0;
+ struct stat64 stat;
+ page_desc_t pd;
+ ulong page_idx;
+ ulong first_empty_pd = 0;
+ int zero_page_counted = 0;
+ size_t expected_size = 0;
if (block_size < 0)
return FALSE;
@@ -898,13 +906,72 @@ restart:
pfn = start;
}
+ expected_size = dd->data_offset;
dd->valid_pages = calloc(sizeof(ulong), max_sect_len + 1);
dd->max_sect_len = max_sect_len;
for (i = 1; i < max_sect_len + 1; i++) {
dd->valid_pages[i] = dd->valid_pages[i - 1];
for (j = 0; j < BITMAP_SECT_LEN; j++, pfn++)
- if (page_is_dumpable(pfn))
- dd->valid_pages[i]++;
+ if (page_is_dumpable(pfn)) {
+ page_idx = dd->valid_pages[i]++;
+
+ offset = dd->data_offset +
+ page_idx * sizeof(pd);
+
+ if (read_pd(dd->dfd, offset, &pd)) {
+ /*
+ * Truncated page descriptor at most
+ * references full page.
+ */
+ expected_size += block_size;
+ goto next;
+ }
+
+ if (pd.offset == 0) {
+ if (!first_empty_pd)
+ first_empty_pd = page_idx;
+ /*
+ * Incomplete pages at most use the
+ * whole page.
+ */
+ expected_size += block_size;
+ } else if (!pd.flags) {
+ /*
+ * Zero page has no compression flags.
+ */
+ if (!zero_page_counted) {
+ expected_size += block_size;
+ zero_page_counted = 1;
+ }
+ } else if (pd.flags) {
+ /* Regular compressed page */
+ expected_size += pd.size;
+ }
+
+next:
+ expected_size += sizeof(pd);
+ }
+ }
+
+ if (stat64(dd->filename, &stat) < 0) {
+ error(INFO, "%s: cannot stat %s\n",
+ DISKDUMP_VALID() ? "diskdump" : "compressed kdump",
+ dd->filename);
+ goto err;
+ }
+
+ if (expected_size > stat.st_size) {
+ error(WARNING,
+ "%s: may be truncated or incomplete\n"
+ " data_offset: %zu\n"
+ " block_size: %d\n"
+ " total_valid_pages: %lu\n"
+ " first_empty_pd: %lu\n"
+ " bytes required: %zu\n"
+ " dumpfile size: %zu\n\n",
+ dd->filename, dd->data_offset,
+ dd->block_size, dd->valid_pages[dd->max_sect_len],
+ first_empty_pd, expected_size, stat.st_size);
}
return TRUE;
--
2.32.0