The original code has one spin_lock 'qgroup_lock' to protect quota
configurations in memory. If we want to add a BTRFS_QGROUP_INFO_KEY,
it will be added to Btree firstly, and then update configurations in
memory,however, a race condition may happen between these operations.
For example:
	->add_qgroup_info_item()
		->add_qgroup_rb()

For the above case, del_qgroup_info_item() may happen just before
add_qgroup_rb().

What's worse, when we want to add a qgroup relation:
	->add_qgroup_relation_item()
		->add_qgroup_relations()

We don't have any checks whether 'src' and 'dst' exist before
add_qgroup_relation_item(), a race condition can also happen for
the above case.

To avoid race condition and have all the necessary checks, we introduce
a mutex lock 'qgroup_ioctl_lock', and we make all the user change operations
protected by the mutex lock.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Creating the subvolume/snapshots(including root subvolume) qgroup
auotomatically when enabling quota.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Steps to reproduce:
	mkfs.btrfs <disk>
	mount <disk> <mnt>
	btrfs quota enable <mnt>
	btrfs sub create <mnt>/subv

	i=1
	while [ $i -le 10000 ]
	do
		dd if=/dev/zero of=<mnt>/subv/data_$i bs=1K count=1
		i=$(($i+1))
		if [ $i -eq 500 ]
		then
			btrfs quota disable $mnt
		fi
	done
	dmesg
Obviously, this warn_on() is unnecessary, and it will be easily triggered.
Just remove it.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

The function btrfs_find_all_roots is responsible to allocate
memory for 'roots' and free it if errors happen,so the caller should not
free it again since the work has been done.

Besides,'tmp' is allocated after the function btrfs_find_all_roots,
so we can return directly if btrfs_find_all_roots() fails.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: NMiao Xie <miaox@cn.fujitsu.com>
Reviewed-by: NJan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

If one of qgroup fails to reserve firstly, we should return immediately,
it is unnecessary to continue check.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

The check work has been done just before the function btrfs_clean_quota_tree
is called, it is not necessary to check it again, remove it.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Return ENOMEM rather trigger BUG_ON, fix it.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: NMiao Xie <miaox@cn.fujitsu.com>
Reviewed-by: NZach Brown <zab@redhat.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Steps to reproduce:

	i=0
	ncases=100

	mkfs.btrfs <disk>
	mount <disk> <mnt>
	btrfs quota enable <mnt>
	btrfs qgroup create 2/1 <mnt>
	while [ $i -le $ncases ]
	do
		btrfs qgroup create 1/$i <mnt>
		btrfs qgroup assign 1/$i 2/1 <mnt>
		i=$(($i+1))
	done

	btrfs quota disable <mnt>
	umount <mnt>
	btrfsck <mnt>

You can also use the commands:
	btrfs-debug-tree <disk> | grep QGROUP

You will find there are still items existed.The reasons why this happens
is because the original code just checks slots[0]==0 and returns.
We try to fix it by deleting the leaf one by one.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

The original code forget to check whether quota has been disabled firstly,
and it will return 'EINVAL' and return error to users if quota has been
disabled,it will be unfriendly and confusing for users to see that.
So just return directly if quota has been disabled.
Signed-off-by: NWang Shilong <wangsl-fnst@cn.fujitsu.com>
Cc: Arne Jansen <sensille@gmx.net>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

The header file will then be installed under /usr/include/linux so that
userspace applications can refer to Btrfs ioctls by name and use the same
structs used internally in the kernel.
Signed-off-by: NFilipe Brandenburger <filbranden@google.com>
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

Currently you can just destroy a qgroup even though it is in use by other qgroups
or has qgroups assigned to it. This patch prevents destruction of qgroups unless
they are completely unused. Otherwise destroy will return EBUSY.
Reported-by: NEric Hopper <hopper@omnifarious.org>
Signed-off-by: NArne Jansen <sensille@gmx.net>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

If a qgroup that has still assignments is deleted by the user, the corresponding
relations are left in the tree. This leads to an unmountable filesystem.
With this patch, those relations are simple ignored.
Reported-by: NEric Hopper <hopper@omnifarious.org>
Signed-off-by: NArne Jansen <sensille@gmx.net>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

We should free quota_root before returning from the error
handling code.
Signed-off-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>

ulist_alloc() has the possibility of returning NULL.
So, it is necessary to check the return value.
Signed-off-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>

Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

Btrfs send/receive uses the aux field to store inode numbers. On
32 bit machines this may become a problem.

Also fix all users of ulist_add and ulist_add_merged.
Reported-by: NArne Jansen <sensille@gmx.net>
Signed-off-by: NAlexander Block <ablock84@googlemail.com>

This reverts commit 5986802c.

Both paths are not error paths but regular cases where non-qgroup
subvols are involved.
Signed-off-by: NChris Mason <chris.mason@fusionio.com>

add_qgroup_rb() never returns NULL, only error pointers.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>

These are returning zero when it should be returning a negative error
code.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>

Signed-off-by: NArne Jansen <sensille@gmx.net>
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>