Hi Mikulas, Mikulas Patocka wrote: > Drop the mutex. > > It doesn't make sense to lock it for a single assignment, this code can't > be executed concurrently. The size should be read with i_size_read which > is automatically protected against concurrent i_size_write. But it seems there are codes which depend on i_mutex for protected access to i_size: e.g. block_write_begin(). > This locking can lead to a deadlock, if someone holds i_mutex while > the device is being suspended, described by Jun'ichi Nomura at > https://www.redhat.com/archives/dm-devel/2009-May/msg00097.html And while my description only mentioned noflush suspend, with 2.6.31-rc, the deadlock can occur under normal suspend because the new barrier code may push bios to deferred queue. > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > > --- > drivers/md/dm.c | 2 -- > 1 file changed, 2 deletions(-) > > Index: linux-2.6.31-rc3-devel/drivers/md/dm.c > =================================================================== > --- linux-2.6.31-rc3-devel.orig/drivers/md/dm.c 2009-07-28 01:20:17.000000000 +0200 > +++ linux-2.6.31-rc3-devel/drivers/md/dm.c 2009-07-28 01:20:27.000000000 +0200 > @@ -1901,9 +1901,7 @@ static void __set_size(struct mapped_dev > { > set_capacity(md->disk, size); > > - mutex_lock(&md->bdev->bd_inode->i_mutex); > i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); > - mutex_unlock(&md->bdev->bd_inode->i_mutex); > } > > static int __bind(struct mapped_device *md, struct dm_table *t, -- Jun'ichi Nomura, NEC Corporation -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
