I make a btrfs use 'mkfs.btrfs -m single -l 16384 -n 16384 /dev/xxx'. After mount it, I run a test script to create lots of files, then soft lockup occurs.
After digging into the source code, I think there is a problem with bio->bi_end_io. when a bio is done, end_io function is called, it does following things: 1: put the bio into async thread waiting for checksum. (end_workqueue_bio) 2: check whether the bio can be checksum-ed. If not, put it back to wait queue.(end_workqueue_fn) 3: If it can be checksum-ed, call end_bio_extent_readpage(). 4: checksum the extent, set_extent_uptodate() and set uptodate flag of the pages belong to the bio.(end_bio_extent_readpage) But when checking whether the bio can be checksum-ed in step 2, it examine the extent_range_uptodate() and uptodate flag of these pages which is set in step 4. So I think there will be a endless loop here. When we say a page is uptodate, we means its checksum is correct, but we must ensure that all of the pages belongs to a btree node is uptodate in order to calculate its checksum. So it's a logical paradox. I am new to btrfs and there may be some mistake about this problem. Any comment is welcome and thanks for your time! -- Zhang Jingwang National Research Centre for High Performance Computers Institute of Computing Technology, Chinese Academy of Sciences No. 6, South Kexueyuan Road, Haidian District Beijing, China -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
