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Commit 31193213 authored by Dongsheng Yang's avatar Dongsheng Yang Committed by Chris Mason
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Btrfs: qgroup: Introduce a may_use to account space_info->bytes_may_use. 



Currently, for pre_alloc or delay_alloc, the bytes will be accounted
in space_info by the three guys.
space_info->bytes_may_use --- space_info->reserved --- space_info->used.
But on the other hand, in qgroup, there are only two counters to account the
bytes, qgroup->reserved and qgroup->excl. And qg->reserved accounts
bytes in space_info->bytes_may_use and qg->excl accounts bytes in
space_info->used. So the bytes in space_info->reserved is not accounted
in qgroup. If so, there is a window we can exceed the quota limit when
bytes is in space_info->reserved.

Example:
	# btrfs quota enable /mnt
	# btrfs qgroup limit -e 10M /mnt
	# for((i=0;i<20;i++));do fallocate -l 1M /mnt/data$i; done
	# sync
	# btrfs qgroup show -pcre /mnt
qgroupid rfer     excl     max_rfer max_excl parent  child
-------- ----     ----     -------- -------- ------  -----
0/5      20987904 20987904 0        10485760 ---     ---

qg->excl is 20987904 larger than max_excl 10485760.

This patch introduce a new counter named may_use to qgroup, then
there are three counters in qgroup to account bytes in space_info
as below.
space_info->bytes_may_use --- space_info->reserved --- space_info->used.
qgroup->may_use           --- qgroup->reserved     --- qgroup->excl

With this patch applied:
	# btrfs quota enable /mnt
	# btrfs qgroup limit -e 10M /mnt
	# for((i=0;i<20;i++));do fallocate -l 1M /mnt/data$i; done
fallocate: /mnt/data9: fallocate failed: Disk quota exceeded
fallocate: /mnt/data10: fallocate failed: Disk quota exceeded
fallocate: /mnt/data11: fallocate failed: Disk quota exceeded
fallocate: /mnt/data12: fallocate failed: Disk quota exceeded
fallocate: /mnt/data13: fallocate failed: Disk quota exceeded
fallocate: /mnt/data14: fallocate failed: Disk quota exceeded
fallocate: /mnt/data15: fallocate failed: Disk quota exceeded
fallocate: /mnt/data16: fallocate failed: Disk quota exceeded
fallocate: /mnt/data17: fallocate failed: Disk quota exceeded
fallocate: /mnt/data18: fallocate failed: Disk quota exceeded
fallocate: /mnt/data19: fallocate failed: Disk quota exceeded
	# sync
	# btrfs qgroup show -pcre /mnt
qgroupid rfer    excl    max_rfer max_excl parent  child
-------- ----    ----    -------- -------- ------  -----
0/5      9453568 9453568 0        10485760 ---     ---

Reported-by: default avatarCyril SCETBON <cyril.scetbon@free.fr>
Signed-off-by: default avatarDongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 804ca127

fs/btrfs/extent-tree.c

+19 −1
Original line number Diff line number Diff line
@@ -5725,8 +5725,12 @@ static int pin_down_extent(struct btrfs_root *root, 


	set_extent_dirty(root->fs_info->pinned_extents, bytenr,

			 bytenr + num_bytes - 1, GFP_NOFS | __GFP_NOFAIL);

	if (reserved)

	if (reserved) {

		btrfs_qgroup_update_reserved_bytes(root->fs_info,

						   root->root_key.objectid,

						   num_bytes, -1);

		trace_btrfs_reserved_extent_free(root, bytenr, num_bytes);

	}

	return 0;

}
@@ -6464,6 +6468,9 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans, 
		btrfs_put_block_group(cache);

		trace_btrfs_reserved_extent_free(root, buf->start, buf->len);

		pin = 0;

		btrfs_qgroup_update_reserved_bytes(root->fs_info,

						   root->root_key.objectid,

						   buf->len, -1);

	}

out:

	if (pin)
@@ -7196,7 +7203,11 @@ static int __btrfs_free_reserved_extent(struct btrfs_root *root, 
			ret = btrfs_discard_extent(root, start, len, NULL);

		btrfs_add_free_space(cache, start, len);

		btrfs_update_reserved_bytes(cache, len, RESERVE_FREE, delalloc);

		btrfs_qgroup_update_reserved_bytes(root->fs_info,

						   root->root_key.objectid,

						   len, -1);

	}



	btrfs_put_block_group(cache);



	trace_btrfs_reserved_extent_free(root, start, len);
@@ -7433,6 +7444,9 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans, 
	BUG_ON(ret); /* logic error */

	ret = alloc_reserved_file_extent(trans, root, 0, root_objectid,

					 0, owner, offset, ins, 1);

	btrfs_qgroup_update_reserved_bytes(root->fs_info,

					   root->root_key.objectid,

					   ins->offset, 1);

	btrfs_put_block_group(block_group);

	return ret;

}
@@ -7579,6 +7593,10 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans, 
		return ERR_PTR(ret);

	}



	btrfs_qgroup_update_reserved_bytes(root->fs_info,

					   root_objectid,

					   ins.offset, 1);



	buf = btrfs_init_new_buffer(trans, root, ins.objectid, level);

	BUG_ON(IS_ERR(buf)); /* -ENOMEM */

fs/btrfs/inode.c

+17 −1
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ 
#include "backref.h"

#include "hash.h"

#include "props.h"

#include "qgroup.h"



struct btrfs_iget_args {

	struct btrfs_key *location;
@@ -753,7 +754,9 @@ static noinline void submit_compressed_extents(struct inode *inode, 
			}

			goto out_free;

		}



		btrfs_qgroup_update_reserved_bytes(root->fs_info,

						   root->root_key.objectid,

						   ins.offset, 1);

		/*

		 * here we're doing allocation and writeback of the

		 * compressed pages
@@ -978,6 +981,10 @@ static noinline int cow_file_range(struct inode *inode, 
		if (ret < 0)

			goto out_unlock;



		btrfs_qgroup_update_reserved_bytes(root->fs_info,

						   root->root_key.objectid,

						   ins.offset, 1);



		em = alloc_extent_map();

		if (!em) {

			ret = -ENOMEM;
@@ -7030,6 +7037,10 @@ static struct extent_map *btrfs_new_extent_direct(struct inode *inode, 
		return ERR_PTR(ret);

	}



	btrfs_qgroup_update_reserved_bytes(root->fs_info,

					   root->root_key.objectid,

					   ins.offset, 1);



	return em;

}
@@ -9583,6 +9594,11 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode, 
				btrfs_end_transaction(trans, root);

			break;

		}



		btrfs_qgroup_update_reserved_bytes(root->fs_info,

						   root->root_key.objectid,

						   ins.offset, 1);



		btrfs_drop_extent_cache(inode, cur_offset,

					cur_offset + ins.offset -1, 0);

fs/btrfs/qgroup.c

+64 −4
Original line number Diff line number Diff line
@@ -72,6 +72,7 @@ struct btrfs_qgroup { 
	/*

	 * reservation tracking

	 */

	u64 may_use;

	u64 reserved;



	/*
@@ -1417,6 +1418,8 @@ static int qgroup_excl_accounting(struct btrfs_fs_info *fs_info, 
	WARN_ON(sign < 0 && qgroup->excl < oper->num_bytes);

	qgroup->excl += sign * oper->num_bytes;

	qgroup->excl_cmpr += sign * oper->num_bytes;

	if (sign > 0)

		qgroup->reserved -= oper->num_bytes;



	qgroup_dirty(fs_info, qgroup);
@@ -1436,6 +1439,8 @@ static int qgroup_excl_accounting(struct btrfs_fs_info *fs_info, 
		qgroup->rfer_cmpr += sign * oper->num_bytes;

		WARN_ON(sign < 0 && qgroup->excl < oper->num_bytes);

		qgroup->excl += sign * oper->num_bytes;

		if (sign > 0)

			qgroup->reserved -= oper->num_bytes;

		qgroup->excl_cmpr += sign * oper->num_bytes;

		qgroup_dirty(fs_info, qgroup);
@@ -2378,6 +2383,61 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 
	return ret;

}



int btrfs_qgroup_update_reserved_bytes(struct btrfs_fs_info *fs_info,

					    u64 ref_root,

					    u64 num_bytes,

					    int sign)

{

	struct btrfs_root *quota_root;

	struct btrfs_qgroup *qgroup;

	int ret = 0;

	struct ulist_node *unode;

	struct ulist_iterator uiter;



	if (!is_fstree(ref_root) || !fs_info->quota_enabled)

		return 0;



	if (num_bytes == 0)

		return 0;



	spin_lock(&fs_info->qgroup_lock);

	quota_root = fs_info->quota_root;

	if (!quota_root)

		goto out;



	qgroup = find_qgroup_rb(fs_info, ref_root);

	if (!qgroup)

		goto out;



	ulist_reinit(fs_info->qgroup_ulist);

	ret = ulist_add(fs_info->qgroup_ulist, qgroup->qgroupid,

			(uintptr_t)qgroup, GFP_ATOMIC);

	if (ret < 0)

		goto out;



	ULIST_ITER_INIT(&uiter);

	while ((unode = ulist_next(fs_info->qgroup_ulist, &uiter))) {

		struct btrfs_qgroup *qg;

		struct btrfs_qgroup_list *glist;



		qg = u64_to_ptr(unode->aux);



		qg->reserved += sign * num_bytes;



		list_for_each_entry(glist, &qg->groups, next_group) {

			ret = ulist_add(fs_info->qgroup_ulist,

					glist->group->qgroupid,

					(uintptr_t)glist->group, GFP_ATOMIC);

			if (ret < 0)

				goto out;

		}

	}



out:

	spin_unlock(&fs_info->qgroup_lock);

	return ret;

}



/*

 * reserve some space for a qgroup and all its parents. The reservation takes

 * place with start_transaction or dealloc_reserve, similar to ENOSPC
@@ -2426,14 +2486,14 @@ int btrfs_qgroup_reserve(struct btrfs_root *root, u64 num_bytes) 
		qg = u64_to_ptr(unode->aux);



		if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_RFER) &&

		    qg->reserved + (s64)qg->rfer + num_bytes >

		    qg->reserved + qg->may_use + (s64)qg->rfer + num_bytes >

		    qg->max_rfer) {

			ret = -EDQUOT;

			goto out;

		}



		if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_EXCL) &&

		    qg->reserved + (s64)qg->excl + num_bytes >

		    qg->reserved + qg->may_use + (s64)qg->excl + num_bytes >

		    qg->max_excl) {

			ret = -EDQUOT;

			goto out;
@@ -2457,7 +2517,7 @@ int btrfs_qgroup_reserve(struct btrfs_root *root, u64 num_bytes) 


		qg = u64_to_ptr(unode->aux);



		qg->reserved += num_bytes;

		qg->may_use += num_bytes;

	}



out:
@@ -2503,7 +2563,7 @@ void btrfs_qgroup_free(struct btrfs_root *root, u64 num_bytes) 


		qg = u64_to_ptr(unode->aux);



		qg->reserved -= num_bytes;

		qg->may_use -= num_bytes;



		list_for_each_entry(glist, &qg->groups, next_group) {

			ret = ulist_add(fs_info->qgroup_ulist,

fs/btrfs/qgroup.h

+4 −0
Original line number Diff line number Diff line
@@ -94,6 +94,10 @@ int btrfs_run_qgroups(struct btrfs_trans_handle *trans, 
int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans,

			 struct btrfs_fs_info *fs_info, u64 srcid, u64 objectid,

			 struct btrfs_qgroup_inherit *inherit);

int btrfs_qgroup_update_reserved_bytes(struct btrfs_fs_info *fs_info,

				       u64 ref_root,

				       u64 num_bytes,

				       int sign);

int btrfs_qgroup_reserve(struct btrfs_root *root, u64 num_bytes);

void btrfs_qgroup_free(struct btrfs_root *root, u64 num_bytes);