BUG 811526 - assert trip with kiocluster & loopback

[pv@xxxxxxxxxxxxxxxxx (dxm@xxxxxxxxxxxx)]

View Incident: 
http://co-op.engr.sgi.com/BugWorks/code/bwxquery.cgi?search=Search&wlong=1&view_type=Bug&wi=811526

Submitter : dxm                       Submitter Domain : engr               
Assigned Engineer : nb                Assigned Domain : sgi.com             
Assigned Group : xfs-linux            Category : software                   
Customer Reported : F                 Priority : 3                          
Project : xfs-linux                   Status : open                         
Description :
Test 049 (xfs on loop) causes an assertion to be tripped when
running with "-o kiocluster". This is quite repeatable, and
I haven't been able to recreate with either "-o kio" or no
"-o" option.

Today is the first time I've tried 049 with kiocluster (due
to it failing earlier in the test due to a qa bug).

The problem occurs when running fsstress on an XFS FS loopback
mounted from an ext2 FS.   (scsi, smp, 1200, small mem)

XFS (dev: 7/0) mounting with KIOBUFIO (clustering)
Start mounting filesystem: loop(7,0)
Ending clean XFS mount for filesystem: loop(7,0)
XFS assertion failed: ismrlocked(&ip->i_iolock, MR_ACCESS | MR_UPDATE) != 0, 
file: xfs_lrw.c, line: 833
kernel BUG at debug.c:48!

Entering kdb (current=0xc2e9a000, pid 19815) on processor 1 Panic: invalid 
operand
due to panic @ 0xc8828da5
eax = 0x0000001a ebx = 0xc6886910 ecx = 0x00000001 edx = 0x00000000 
esi = 0x00000002 edi = 0x00000002 esp = 0xc2e9bad8 eip = 0xc8828da5 
ebp = 0xc2e9bae4 xss = 0x00000018 xcs = 0x00000010 eflags = 0x00010246 
xds = 0x00000018 xes = 0x00000018 origeax = 0xffffffff &regs = 0xc2e9baa4
[1]kdb> bt
    EBP       EIP         Function(args)
0xc2e9bae4 0xc8828da5 [xfs_support]assfail+0x2d (0xc89b6ee0, 0xc89b6b97, 0x341)
                               xfs_support .text 0xc8828060 0xc8828d78 
0xc8828dac
0xc2e9bb10 0xc8999671 [xfs]xfs_bmap+0x1bd (0xc6886928, 0x2c000, 0x0, 0x1000, 
0x2)
                               xfs .text 0xc8927060 0xc89994b4 0xc899983c
0xc2e9bb44 0xc8997ede [xfs]linvfs_pb_bmap+0x6e (0xc3daac80, 0x2c000, 0x0, 
0x1000, 0xc2e9bb94)
                               xfs .text 0xc8927060 0xc8997e70 0xc8997eec
0xc2e9bbb0 0xc883251e [pagebuf]__pb_block_prepare_write_async+0x7a (0xc3daac80, 
0xc10e8940, 0x800, 0xc00, 0x0)
                               pagebuf .text 0xc882e060 0xc88324a4 0xc88326e4
0xc2e9bbe8 0xc8832742 [pagebuf]pagebuf_prepare_write+0x5e (0xc67ea240, 
0xc10e8940, 0x800, 0xc00)
                               pagebuf .text 0xc882e060 0xc88326e4 0xc883274c
0xc2e9bc44 0xc0171e86 lo_send+0xba (0xc7f9e0cc, 0xc2d8a800, 0x400, 0x2c800, 0x0)
                               kernel .text 0xc0100000 0xc0171dcc 0xc0171fac
0xc2e9bcb8 0xc01723bf do_lo_request+0x313 (0xc0374334)
                               kernel .text 0xc0100000 0xc01720ac 0xc01724cc
0xc2e9bd00 0xc0167f4c __make_request+0x61c (0xc0374334, 0x1, 0xc5f236c0, 0x0, 
0x701)
                               kernel .text 0xc0100000 0xc0167930 0xc0167fc0
0xc2e9bd44 0xc01680ff generic_make_request+0x13f (0x1, 0xc5f236c0, 0x0, 0x0, 
0x0)
                               kernel .text 0xc0100000 0xc0167fc0 0xc0168188
0xc2e9bd68 0xc01681e8 submit_bh+0x60 (0x1, 0xc5f236c0)
                               kernel .text 0xc0100000 0xc0168188 0xc01681f0
0xc2e9bd94 0xc016839a ll_rw_block+0x15e (0x1, 0x1, 0xc2e9bdb8, 0xc52635a0)
                               kernel .text 0xc0100000 0xc016823c 0xc0168418
0xc2e9bf74 0xc0135480 fsync_inode_buffers+0xc4 (0xc7671c80)
                               kernel .text 0xc0100000 0xc01353bc 0xc0135564
0xc2e9bf88 0xc01577a6 ext2_fsync_inode+0xe (0xc7671c80, 0x0)
                               kernel .text 0xc0100000 0xc0157798 0xc01577e0
0xc2e9bf98 0xc0157793 ext2_sync_file+0x13 (0xc52635a0, 0xc4adde40, 0x0, 
0xc2e9a000)
                               kernel .text 0xc0100000 0xc0157780 0xc0157798
0xc2e9bfbc 0xc0134a88 sys_fsync+0x54 (0x3, 0xbffff9c0, 0x804d8b8, 0x4000ae60, 
0xbffffb6c)
                               kernel .text 0xc0100000 0xc0134a34 0xc0134aac
           0xc0109047 system_call+0x33
                               kernel .text 0xc0100000 0xc0109014 0xc010904c