On Wed, Feb 11, 2015 at 1:24 AM, Forrest Liu <forrestl@xxxxxxxxxxxx>
wrote:
Removing large amount of block group in a transaction may encounters
BUG_ON() in btrfs_orphan_add(). That is because
btrfs_orphan_reserve_metadata()
will grab metadata reservation from transaction handle, and
btrfs_delete_unused_bgs() didn't reserve metadata for trnasaction
handle when
delete unused block group.
The problem can be reproduce by following script
mntpath=/btrfs
loopdev=/dev/loop0
filepath=/home/forrest/image
umount $mntpath
losetup -d $loopdev
truncate --size 1000g $filepath
losetup $loopdev $filepath
mkfs.btrfs -f $loopdev
mount $loopdev $mntpath
for j in `seq 1 1 1000`; do
fallocate -l 1g $mntpath/$j
done
# wait cleaner thread remove unused block group
sleep 300
The call trace that results from the BUG_ON() is:
[ 613.093084] ------------[ cut here ]------------
[ 613.097928] kernel BUG at fs/btrfs/inode.c:3142!
This should fix a hard to trigger bug we've seen in production here. I
was on a different (wrong) track for explaining it, so your timing is
excellent.
Thanks.
-chris
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