On Fri, Mar 20, 2015 at 04:22:11PM +0200, Vitaly Chernooky wrote: > > AFAICS, any threads blocked on f_pos_lock are not holding anything else and > > cannot impede the rest. What am I missing here? > > As far as I understand it is true only for files on regular filesystem > like ext4. Let's to see how XEN guys run into trouble with that > f_pos_lock: What does it have to do with filesystem type involved? The only place that takes f_pos_lock is __fdget_pos(), with only one caller in the entire tree - fdget_pos(). Which is static in fs/read_write.c and all its callers are in right in the beginning of sys_<something>. Is it just that they have read() on procfs file blocked waiting for something and a bunch of other read/write on the same descriptor blocked on ->f_pos_mutex waiting for that sucker to finish? Then basically they are asking to waive XSI 2.9.7 for that file - behaviour *is* required by POSIX. What file it is and what is the first read() (or write(), whatever) blocked on? Stack traces would be useful for the latter... -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
