Denys Vlasenko wrote: > Hi Al, Benjamin, David, > > struct kiocb is placed on stack by, for example, do_sync_write(). > Eventually it contributes to xfs writeout path's stack usage, among others. > This is *the* path which causes 4k stack overflows on i386 with xfs. > > This patch trivially reorders fields of this structure, > and makes some of them smaller. Great, thanks for doing this. I see one fatal bug, though. Can you fix it up and resubmit? - unsigned long ki_flags; + unsigned short ki_flags; /* range: 0..2 */ Careful, ki_flags is used by the bitops routines which require an unsigned long. I'd just leave ki_flags as is. > ki_nr_segs: ulong -> uint: nobody uses 4 billion element writev's > (and it would not work anyway) Indeed. Maybe explicitly mention that it's safe 'cause we pass ki_nbytes to rw_copy_check_uvector() for comparison against UIO_MAXIOV before we store it in the kiocb. + /*unsigned short ki_opcode; - moved up for denser packing */ Don't bother commenting out fields that are moved, just move 'em. Otherwise it looks great, thanks. - z -- 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
