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![Qu Wenruo](/assets/img/avatar_default.png)
[BUG] For the following case, btrfs can underflow qgroup reserved space at an error path: (Page size 4K, function name without "btrfs_" prefix) Task A | Task B ---------------------------------------------------------------------- Buffered_write [0, 2K) | |- check_data_free_space() | | |- qgroup_reserve_data() | | Range aligned to page | | range [0, 4K) <<< | | 4K bytes reserved <<< | |- copy pages to page cache | | Buffered_write [2K, 4K) | |- check_data_free_space() | | |- qgroup_reserved_data() | | Range alinged to page | | range [0, 4K) | | Already reserved by A <<< | | 0 bytes reserved <<< | |- delalloc_reserve_metadata() | | And it *FAILED* (Maybe EQUOTA) | |- free_reserved_data_space() |- qgroup_free_data() Range aligned to page range [0, 4K) Freeing 4K (Special thanks to Chandan for the detailed report and analyse) [CAUSE] Above Task B is freeing reserved data range [0, 4K) which is actually reserved by Task A. And at writeback time, page dirty by Task A will go through writeback routine, which will free 4K reserved data space at file extent insert time, causing the qgroup underflow. [FIX] For btrfs_qgroup_free_data(), add @reserved parameter to only free data ranges reserved by previous btrfs_qgroup_reserve_data(). So in above case, Task B will try to free 0 byte, so no underflow. Reported-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Reviewed-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Tested-by: Chandan Rajendra <chandan@linux.vnet.ibm.com> Signed-off-by: David Sterba <dsterba@suse.com>
256 lines
8.4 KiB
C
256 lines
8.4 KiB
C
/*
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* Copyright (C) 2014 Facebook. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __BTRFS_QGROUP__
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#define __BTRFS_QGROUP__
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#include "ulist.h"
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#include "delayed-ref.h"
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/*
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* Btrfs qgroup overview
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*
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* Btrfs qgroup splits into 3 main part:
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* 1) Reserve
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* Reserve metadata/data space for incoming operations
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* Affect how qgroup limit works
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*
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* 2) Trace
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* Tell btrfs qgroup to trace dirty extents.
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*
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* Dirty extents including:
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* - Newly allocated extents
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* - Extents going to be deleted (in this trans)
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* - Extents whose owner is going to be modified
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*
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* This is the main part affects whether qgroup numbers will stay
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* consistent.
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* Btrfs qgroup can trace clean extents and won't cause any problem,
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* but it will consume extra CPU time, it should be avoided if possible.
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*
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* 3) Account
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* Btrfs qgroup will updates its numbers, based on dirty extents traced
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* in previous step.
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*
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* Normally at qgroup rescan and transaction commit time.
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*/
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/*
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* Record a dirty extent, and info qgroup to update quota on it
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* TODO: Use kmem cache to alloc it.
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*/
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struct btrfs_qgroup_extent_record {
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struct rb_node node;
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u64 bytenr;
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u64 num_bytes;
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struct ulist *old_roots;
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};
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/*
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* one struct for each qgroup, organized in fs_info->qgroup_tree.
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*/
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struct btrfs_qgroup {
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u64 qgroupid;
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/*
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* state
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*/
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u64 rfer; /* referenced */
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u64 rfer_cmpr; /* referenced compressed */
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u64 excl; /* exclusive */
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u64 excl_cmpr; /* exclusive compressed */
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/*
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* limits
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*/
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u64 lim_flags; /* which limits are set */
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u64 max_rfer;
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u64 max_excl;
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u64 rsv_rfer;
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u64 rsv_excl;
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/*
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* reservation tracking
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*/
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u64 reserved;
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/*
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* lists
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*/
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struct list_head groups; /* groups this group is member of */
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struct list_head members; /* groups that are members of this group */
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struct list_head dirty; /* dirty groups */
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struct rb_node node; /* tree of qgroups */
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/*
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* temp variables for accounting operations
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* Refer to qgroup_shared_accounting() for details.
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*/
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u64 old_refcnt;
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u64 new_refcnt;
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};
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/*
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* For qgroup event trace points only
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*/
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#define QGROUP_RESERVE (1<<0)
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#define QGROUP_RELEASE (1<<1)
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#define QGROUP_FREE (1<<2)
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int btrfs_quota_enable(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info);
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int btrfs_quota_disable(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info);
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int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
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void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);
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int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
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bool interruptible);
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int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 src, u64 dst);
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int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 src, u64 dst);
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int btrfs_create_qgroup(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 qgroupid);
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int btrfs_remove_qgroup(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 qgroupid);
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int btrfs_limit_qgroup(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 qgroupid,
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struct btrfs_qgroup_limit *limit);
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int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info);
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void btrfs_free_qgroup_config(struct btrfs_fs_info *fs_info);
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struct btrfs_delayed_extent_op;
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/*
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* Inform qgroup to trace one dirty extent, its info is recorded in @record.
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* So qgroup can account it at transaction committing time.
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*
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* No lock version, caller must acquire delayed ref lock and allocated memory,
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* then call btrfs_qgroup_trace_extent_post() after exiting lock context.
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*
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* Return 0 for success insert
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* Return >0 for existing record, caller can free @record safely.
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* Error is not possible
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*/
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int btrfs_qgroup_trace_extent_nolock(
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struct btrfs_fs_info *fs_info,
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struct btrfs_delayed_ref_root *delayed_refs,
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struct btrfs_qgroup_extent_record *record);
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/*
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* Post handler after qgroup_trace_extent_nolock().
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*
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* NOTE: Current qgroup does the expensive backref walk at transaction
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* committing time with TRANS_STATE_COMMIT_DOING, this blocks incoming
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* new transaction.
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* This is designed to allow btrfs_find_all_roots() to get correct new_roots
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* result.
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*
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* However for old_roots there is no need to do backref walk at that time,
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* since we search commit roots to walk backref and result will always be
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* correct.
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*
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* Due to the nature of no lock version, we can't do backref there.
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* So we must call btrfs_qgroup_trace_extent_post() after exiting
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* spinlock context.
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*
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* TODO: If we can fix and prove btrfs_find_all_roots() can get correct result
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* using current root, then we can move all expensive backref walk out of
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* transaction committing, but not now as qgroup accounting will be wrong again.
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*/
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int btrfs_qgroup_trace_extent_post(struct btrfs_fs_info *fs_info,
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struct btrfs_qgroup_extent_record *qrecord);
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/*
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* Inform qgroup to trace one dirty extent, specified by @bytenr and
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* @num_bytes.
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* So qgroup can account it at commit trans time.
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*
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* Better encapsulated version, with memory allocation and backref walk for
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* commit roots.
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* So this can sleep.
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*
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* Return 0 if the operation is done.
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* Return <0 for error, like memory allocation failure or invalid parameter
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* (NULL trans)
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*/
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int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 bytenr, u64 num_bytes,
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gfp_t gfp_flag);
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/*
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* Inform qgroup to trace all leaf items of data
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*
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* Return 0 for success
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* Return <0 for error(ENOMEM)
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*/
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int btrfs_qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info,
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struct extent_buffer *eb);
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/*
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* Inform qgroup to trace a whole subtree, including all its child tree
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* blocks and data.
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* The root tree block is specified by @root_eb.
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*
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* Normally used by relocation(tree block swap) and subvolume deletion.
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*
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* Return 0 for success
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* Return <0 for error(ENOMEM or tree search error)
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*/
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int btrfs_qgroup_trace_subtree(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct extent_buffer *root_eb,
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u64 root_gen, int root_level);
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int
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btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info,
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u64 bytenr, u64 num_bytes,
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struct ulist *old_roots, struct ulist *new_roots);
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int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info);
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int btrfs_run_qgroups(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info);
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int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info, u64 srcid, u64 objectid,
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struct btrfs_qgroup_inherit *inherit);
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void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
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u64 ref_root, u64 num_bytes);
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static inline void btrfs_qgroup_free_delayed_ref(struct btrfs_fs_info *fs_info,
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u64 ref_root, u64 num_bytes)
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{
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trace_btrfs_qgroup_free_delayed_ref(fs_info, ref_root, num_bytes);
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btrfs_qgroup_free_refroot(fs_info, ref_root, num_bytes);
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}
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#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
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int btrfs_verify_qgroup_counts(struct btrfs_fs_info *fs_info, u64 qgroupid,
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u64 rfer, u64 excl);
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#endif
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/* New io_tree based accurate qgroup reserve API */
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int btrfs_qgroup_reserve_data(struct inode *inode,
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struct extent_changeset **reserved, u64 start, u64 len);
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int btrfs_qgroup_release_data(struct inode *inode, u64 start, u64 len);
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int btrfs_qgroup_free_data(struct inode *inode,
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struct extent_changeset *reserved, u64 start, u64 len);
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int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
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bool enforce);
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void btrfs_qgroup_free_meta_all(struct btrfs_root *root);
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void btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes);
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void btrfs_qgroup_check_reserved_leak(struct inode *inode);
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#endif /* __BTRFS_QGROUP__ */
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