btrfs: Change qgroup_meta_rsv to 64bit

Using an int value is causing qg->reserved to become negative and
exclusive -EDQUOT to be reached prematurely.

This affects exclusive qgroups only.

TEST CASE:

DEVICE=/dev/vdb
MOUNTPOINT=/mnt
SUBVOL=$MOUNTPOINT/tmp

umount $SUBVOL
umount $MOUNTPOINT

mkfs.btrfs -f $DEVICE
mount /dev/vdb $MOUNTPOINT
btrfs quota enable $MOUNTPOINT
btrfs subvol create $SUBVOL
umount $MOUNTPOINT
mount /dev/vdb $MOUNTPOINT
mount -o subvol=tmp $DEVICE $SUBVOL
btrfs qgroup limit -e 3G $SUBVOL

btrfs quota rescan /mnt -w

for i in `seq 1 44000`; do
  dd if=/dev/zero of=/mnt/tmp/test_$i bs=10k count=1
  if [[ $? > 0 ]]; then
     btrfs qgroup show -pcref $SUBVOL
     exit 1
  fi
done

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
[ add reproducer to changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -1258,7 +1258,7 @@ struct btrfs_root {
 	atomic_t will_be_snapshoted;
 
 	/* For qgroup metadata space reserve */
-	atomic_t qgroup_meta_rsv;
+	atomic64_t qgroup_meta_rsv;
 };
 static inline u32 btrfs_inode_sectorsize(const struct inode *inode)
 {

fs/btrfs/disk-io.c

@@ -1342,7 +1342,7 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,
 	atomic_set(&root->orphan_inodes, 0);
 	atomic_set(&root->refs, 1);
 	atomic_set(&root->will_be_snapshoted, 0);
-	atomic_set(&root->qgroup_meta_rsv, 0);
+	atomic64_set(&root->qgroup_meta_rsv, 0);
 	root->log_transid = 0;
 	root->log_transid_committed = -1;
 	root->last_log_commit = 0;

fs/btrfs/qgroup.c

@@ -2948,20 +2948,20 @@ int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
 	ret = qgroup_reserve(root, num_bytes, enforce);
 	if (ret < 0)
 		return ret;
-	atomic_add(num_bytes, &root->qgroup_meta_rsv);
+	atomic64_add(num_bytes, &root->qgroup_meta_rsv);
 	return ret;
 }
 
 void btrfs_qgroup_free_meta_all(struct btrfs_root *root)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
-	int reserved;
+	u64 reserved;
 
 	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) ||
 	    !is_fstree(root->objectid))
 		return;
 
-	reserved = atomic_xchg(&root->qgroup_meta_rsv, 0);
+	reserved = atomic64_xchg(&root->qgroup_meta_rsv, 0);
 	if (reserved == 0)
 		return;
 	btrfs_qgroup_free_refroot(fs_info, root->objectid, reserved);
@@ -2976,8 +2976,8 @@ void btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes)
 		return;
 
 	BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
-	WARN_ON(atomic_read(&root->qgroup_meta_rsv) < num_bytes);
-	atomic_sub(num_bytes, &root->qgroup_meta_rsv);
+	WARN_ON(atomic64_read(&root->qgroup_meta_rsv) < num_bytes);
+	atomic64_sub(num_bytes, &root->qgroup_meta_rsv);
 	btrfs_qgroup_free_refroot(fs_info, root->objectid, num_bytes);
 }