recent disk-related breakage

[Colin Percival]

Some time in early December, disk I/O broke.  The EC2 image built from r291495
works fine; the EC2 image built from r292413 is broken.

Symptoms:
1. growfs reports "superblock not recognized"

2. fsck reports lots of "UNKNOWN FILE TYPE"s and after a few seconds provokes
"panic: XEN disk driver data cannot cross a page boundary"
xbd_mksegarray() at xbd_mksegarray+0x4b/frame 0xfffffe0f4dadb420

xbd_queue_cb() at xbd_queue_cb+0x1e8/frame 0xfffffe0f4dadb490

bus_dmamap_load_bio() at bus_dmamap_load_bio+0xad/frame 0xfffffe0f4dadb4f0

xbd_startio() at xbd_startio+0x194/frame 0xfffffe0f4dadb530

xbd_strategy() at xbd_strategy+0x6a/frame 0xfffffe0f4dadb560

g_disk_start() at g_disk_start+0x37c/frame 0xfffffe0f4dadb5d0

g_io_request() at g_io_request+0x39d/frame 0xfffffe0f4dadb630

g_part_start() at g_part_start+0x2b5/frame 0xfffffe0f4dadb6b0

g_io_request() at g_io_request+0x39d/frame 0xfffffe0f4dadb710

g_io_request() at g_io_request+0x39d/frame 0xfffffe0f4dadb770

g_dev_strategy() at g_dev_strategy+0x171/frame 0xfffffe0f4dadb7b0

physio() at physio+0x440/frame 0xfffffe0f4dadb850

devfs_read_f() at devfs_read_f+0xe7/frame 0xfffffe0f4dadb8b0

dofileread() at dofileread+0x98/frame 0xfffffe0f4dadb900

kern_readv() at kern_readv+0x68/frame 0xfffffe0f4dadb950

sys_read() at sys_read+0x60/frame 0xfffffe0f4dadb9a0


Does anyone remember touching any relevant bits of code in that timeframe?

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid