BUG 794396 - xfs_zero_last_block "unwritten" & "DELWRI" messages

[pv@xxxxxxxxxxxxxxxxxxxxxx (dxm@xxxxxxxxxxxx)]

View Incident: 
http://co-op.engr.sgi.com/BugWorks/code/bwxquery.cgi?search=Search&wlong=1&view_type=Bug&wi=794396

Submitter : dxm                       Submitter Domain : engr               
Assigned Engineer : btg               Assigned Domain : sgi.com             
Assigned Group : xfs-linux            Category : software                   
Customer Reported : F                 Priority : 3                          
Project : xfs-linux                   Status : open                         
Description :
under certain circumstances, xfs_zero_last_block generates
messages:

xfs_zero_last_block: unwritten?
xfs_zero_last_block: We want DELWRI? not waiting?

And eventually things fail. This might be a related panic:

XFS assertion failed: offset_fsb >= imap[nimaps].br_startoff + 
imap[i].br_blockcount, file: xfs_lrw.c, line: 1681
kernel BUG at xfs_debug.c:50!

Entering kdb (0xc1f6e000) Panic: invalid operand
due to panic @ 0xc4887cc9
eax = 0x0000001e ebx = 0x00000360 ecx = 0xc02c1314 edx = 0xc33ddf78 
esi = 0xc2c71ca0 edi = 0xc1f6fda0 esp = 0xc1f6fd00 eip = 0xc4887cc9 
ebp = 0xc1f6fd0c  ss = 0x00000018  cs = 0x00000010 eflags = 0x00010292 
 ds = 0x00000018  es = 0x00000018 origeax = 0xffffffff &regs = 0xc1f6fccc
kdb> bt
    EBP       EIP         Function(args)
0xc1f6fd0c 0xc4887cc9 [xfs]assfail+0x2d (0xc48b06a0, 0xc48afb24, 0x691)
                               xfs .text 0xc4816060 0xc4887c9c 0xc4887cd0
0xc1f6fe0c 0xc488eb8e [xfs]xfs_iomap_write_convert+0x74e (0xc2fc5c2c, 0x167000, 
0x0, 0x1000, 0xc1f6ffa8)
                               xfs .text 0xc4816060 0xc488e440 0xc488ed04
0xc1f6fecc 0xc488d4df [xfs]xfs_iomap_write+0x12b (0xc2fc5c2c, 0x167000, 0x0, 
0x1000, 0xc1f6ffa8)
                               xfs .text 0xc4816060 0xc488d3b4 0xc488d5ec
0xc1f6ff0c 0xc488cefa [xfs]xfs_bmap+0x26e (0xc2fc5af8, 0x167000, 0x0, 0x1000, 
0x10010002)
                               xfs .text 0xc4816060 0xc488cc8c 0xc488cfc4
0xc1f6ff58 0xc488a93f [xfs]linvfs_pb_bmap+0x117 (0xc1b76680, 0x167000, 0x0, 
0x1000, 0xc1f6ffa8)
                               xfs .text 0xc4816060 0xc488a828 0xc488a95c
0xc1f6ffc0 0xc480f135 [pagebuf]pb_delalloc_convert+0x61 (0xc1055fc4, 
0x10000000, 0x1, 0xf00)
                               pagebuf .text 0xc480a060 0xc480f0d4 0xc480f240
0xc1f6ffec 0xc480f39d [pagebuf]page_cleaner_daemon+0x15d
                               pagebuf .text 0xc480a060 0xc480f240 0xc480f43c
           0xc01074ff kernel_thread+0x23
                               kernel .text 0xc0100000 0xc01074dc 0xc0107514

XFS qa test 013 will eventually show up this bug.