<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content="text/html; charset=utf-8" http-equiv=content-type> <STYLE type=text/css> body {font-size:12pt; font-family:simsun,serif;} </STYLE>  <STYLE type=text/css>  blockquote {margin-top:0; margin-bottom:0; margin-left:2em;} ol,ul {margin-top:0; margin-bottom:0;} p {margin:0; padding:0;} body {padding:0; margin:0;} </STYLE> <BASE target=_blank> <META name=GENERATOR content="MSHTML 9.00.8112.16437"></HEAD> <BODY style="LINE-HEIGHT: 1.3; BORDER-RIGHT-WIDTH: 0px; MARGIN: 12px; BORDER-TOP-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; BORDER-LEFT-WIDTH: 0px"><STATIONERY> <DIV> <DIV><FONT color=#000000 size=3 face=宋体>hi, </FONT>all</DIV> <DIV style="TEXT-INDENT: 2em">i am interested in facebook flashcache,which uses device mapper to make ssd as a disk cache, i want to add some functions in it, so i modify some codes. but when i use dm_io_async_bvec(1, &job->cache, WRITE,bio->bi_io_vec,bio->bi_idx, io_callback, kcached_job) (the params is all right)submit a bio. </DIV> <DIV style="TEXT-INDENT: 2em">it does not call the io_callback function. i use systemtap to trace the function. the result like this:(sometimes is: enter dm_io_async_bvec; enter submit_bio; enter generic_make_request, generic_make_request return, submit_bio return, dm_io_async_bvec return. sometimes is :enter dm_io_async_bvec; enter submit_bio; enter generic_make_request, dm_io_async_bvec return) </DIV> <DIV style="TEXT-INDENT: 2em">it do not know why, and why it did not call the io_callback.</DIV> <DIV> </DIV> <DIV>thanks.</DIV> <DIV><FONT color=#000000 size=3 face=宋体></FONT> </DIV> <DIV align=left><FONT color=#c0c0c0 size=2 face=Verdana>2011-12-01</FONT></DIV><FONT size=2 face=Verdana> <HR style="WIDTH: 122px; HEIGHT: 2px" id=SignNameHR align=left SIZE=2> <DIV><FONT color=#c0c0c0 size=2 face=Verdana><SPAN id=_FlashSignName>wzpywzh</SPAN></FONT></DIV></FONT></DIV></STATIONERY></BODY></HTML>