Messages in this thread |  | | Date | Mon, 29 May 2006 23:40:11 +0200 | | From | Olaf Hering <> | | Subject | cramfs corruption after BLKFLSBUF on loop device |
| |
This script will cause cramfs decompression errors, on SMP at least:
#!/bin/bash while :;do blockdev --flushbufs /dev/loop0;done </dev/null &>/dev/null& while :;do ps faxs </dev/null &>/dev/null&done </dev/null &>/dev/null& while :;do dmesg </dev/null &>/dev/null&done </dev/null &>/dev/null& while :;do find /mounts/instsys -type f -print0|xargs -0 cat &>/dev/null;done
... Error -3 while decompressing! c0000000009592a2(2649)->c0000000edf87000(4096) Error -3 while decompressing! c000000000959298(2520)->c0000000edbc7000(4096) Error -3 while decompressing! c000000000959c70(2489)->c0000000f1482000(4096) Error -3 while decompressing! c00000000095a629(2355)->c0000000edaff000(4096) Error -3 while decompressing! ...
evms_access does the ioctl (lots of them) on the loop device. Its a long standing bug, 2.6.5 fails as well. cramfs_read() clears parts of the src buffer because the page is not uptodate. invalidate_bdev() touched the page last. cramfs_read() was called from line 480 or 490 when the PageUptodate(page) test fails.
... 464 static int cramfs_readpage(struct file *file, struct page * page) .. 479 if (page->index) 480 start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4, 4); .. 488 bytes_filled = cramfs_uncompress_block(pgdata, 489 PAGE_CACHE_SIZE, 490 cramfs_read(sb, start_offset, compr_len), 491 compr_len); ...
There are rumors that cramfs is not smp safe... Maybe the only hope is to tell evms to not do that ioctl for loop. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |