On Mon, 2010-03-15 at 16:34 +0000, Al Viro wrote: > On Mon, Mar 15, 2010 at 10:04:46AM -0600, Andreas Dilger wrote: > > On 2010-03-13, at 13:30, Francis Moreau wrote: > > >I've some shell scripts which try to find out the filesystem hosted by > > >a block device. > > > > > >They basically do this: > > > > > > mount /dev/sdc1 /mnt > > > fs=$(stat -f -c %T $mount_point) > > > umount /mnt > > > > Mounting an in-use filesystem is a bad idea. > > Huh? mount() will happily create another vfsmount refering to the same > superblock in that case. It *is* OK to mount the same block device twice; > any fs that uses get_sb_bdev() will DTRT. > > It should be safe. The lack of error checking after mount, OTOH, is not. I started seeing similar behavior in autofs after the pnode patches went in. I was never able to decide if I was doing something wrong or if there had been some latency in reducing reference counts introduced. Also, I couldn't see anything in the kernel code that that even looked like it would cause this so I didn't see any use in reporting it. Instead I began using a retry loop with a short delay when umounting mounts. Ian -- 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
