On Tue, Aug 16, 2011 at 02:37:53PM +0800, Tao Ma wrote: > From: Tao Ma <boyu.mt@xxxxxxxxxx> > > EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten should > be done simultaneously since ext4_end_io_nolock always clear the flag and > decrease the counter in the same time. > > We don't increase i_aiodio_unwritten when setting EXT4_IO_END_UNWRITTEN so > it will go nagative and causes some process to wait forever. > > Part of the patch came from Eric in his e-mail, but it doesn't fix the problem > met by Michael actually. > http://marc.info/?l=linux-ext4&m=131316851417460&w=2 > > Reported-and-Tested-by: Michael Tokarev<mjt@xxxxxxxxxx> > Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> > Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx> Thanks I've taken this into the ext4 tree. I am a bit worried this will trigger a GCC warning: + /* + * It may be over-defensive here to check EXT4_IO_END_UNWRITTEN now, + * but being more careful is always safe for the future change. + */ inode = io_end->inode; + if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { + io_end->flag |= EXT4_IO_END_UNWRITTEN; + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); + } /* Add the io_end to per-inode completed io list*/ spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); ... since in Google we've been compiling with -Werror, but it's not causing an error on gcc 4.4, which is what I still have on my laptop. It may be that newer versions of GCC are smart enough to notice tha the above is dead code, and then complain with a warning. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
