linux/fs/btrfs/qgroup.h
Filipe Manana d4135134ab btrfs: avoid blocking on space revervation when doing nowait dio writes
When doing a NOWAIT direct IO write, if we can NOCOW then it means we can
proceed with the non-blocking, NOWAIT path. However reserving the metadata
space and qgroup meta space can often result in blocking - flushing
delalloc, wait for ordered extents to complete, trigger transaction
commits, etc, going against the semantics of a NOWAIT write.

So make the NOWAIT write path to try to reserve all the metadata it needs
without resulting in a blocking behaviour - if we get -ENOSPC or -EDQUOT
then return -EAGAIN to make the caller fallback to a blocking direct IO
write.

This is part of a patchset comprised of the following patches:

  btrfs: avoid blocking on page locks with nowait dio on compressed range
  btrfs: avoid blocking nowait dio when locking file range
  btrfs: avoid double nocow check when doing nowait dio writes
  btrfs: stop allocating a path when checking if cross reference exists
  btrfs: free path at can_nocow_extent() before checking for checksum items
  btrfs: release path earlier at can_nocow_extent()
  btrfs: avoid blocking when allocating context for nowait dio read/write
  btrfs: avoid blocking on space revervation when doing nowait dio writes

The following test was run before and after applying this patchset:

  $ cat io-uring-nodatacow-test.sh
  #!/bin/bash

  DEV=/dev/sdc
  MNT=/mnt/sdc

  MOUNT_OPTIONS="-o ssd -o nodatacow"
  MKFS_OPTIONS="-R free-space-tree -O no-holes"

  NUM_JOBS=4
  FILE_SIZE=8G
  RUN_TIME=300

  cat <<EOF > /tmp/fio-job.ini
  [io_uring_rw]
  rw=randrw
  fsync=0
  fallocate=posix
  group_reporting=1
  direct=1
  ioengine=io_uring
  iodepth=64
  bssplit=4k/20:8k/20:16k/20:32k/10:64k/10:128k/5:256k/5:512k/5:1m/5
  filesize=$FILE_SIZE
  runtime=$RUN_TIME
  time_based
  filename=foobar
  directory=$MNT
  numjobs=$NUM_JOBS
  thread
  EOF

  echo performance | \
     tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

  umount $MNT &> /dev/null
  mkfs.btrfs -f $MKFS_OPTIONS $DEV &> /dev/null
  mount $MOUNT_OPTIONS $DEV $MNT

  fio /tmp/fio-job.ini

  umount $MNT

The test was run a 12 cores box with 64G of ram, using a non-debug kernel
config (Debian's default config) and a spinning disk.

Result before the patchset:

 READ: bw=407MiB/s (427MB/s), 407MiB/s-407MiB/s (427MB/s-427MB/s), io=119GiB (128GB), run=300175-300175msec
WRITE: bw=407MiB/s (427MB/s), 407MiB/s-407MiB/s (427MB/s-427MB/s), io=119GiB (128GB), run=300175-300175msec

Result after the patchset:

 READ: bw=436MiB/s (457MB/s), 436MiB/s-436MiB/s (457MB/s-457MB/s), io=128GiB (137GB), run=300044-300044msec
WRITE: bw=435MiB/s (456MB/s), 435MiB/s-435MiB/s (456MB/s-456MB/s), io=128GiB (137GB), run=300044-300044msec

That's about +7.2% throughput for reads and +6.9% for writes.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2022-05-16 17:03:10 +02:00

438 lines
14 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2014 Facebook. All rights reserved.
*/
#ifndef BTRFS_QGROUP_H
#define BTRFS_QGROUP_H
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include <linux/kobject.h>
#include "ulist.h"
#include "delayed-ref.h"
/*
* Btrfs qgroup overview
*
* Btrfs qgroup splits into 3 main part:
* 1) Reserve
* Reserve metadata/data space for incoming operations
* Affect how qgroup limit works
*
* 2) Trace
* Tell btrfs qgroup to trace dirty extents.
*
* Dirty extents including:
* - Newly allocated extents
* - Extents going to be deleted (in this trans)
* - Extents whose owner is going to be modified
*
* This is the main part affects whether qgroup numbers will stay
* consistent.
* Btrfs qgroup can trace clean extents and won't cause any problem,
* but it will consume extra CPU time, it should be avoided if possible.
*
* 3) Account
* Btrfs qgroup will updates its numbers, based on dirty extents traced
* in previous step.
*
* Normally at qgroup rescan and transaction commit time.
*/
/*
* Special performance optimization for balance.
*
* For balance, we need to swap subtree of subvolume and reloc trees.
* In theory, we need to trace all subtree blocks of both subvolume and reloc
* trees, since their owner has changed during such swap.
*
* However since balance has ensured that both subtrees are containing the
* same contents and have the same tree structures, such swap won't cause
* qgroup number change.
*
* But there is a race window between subtree swap and transaction commit,
* during that window, if we increase/decrease tree level or merge/split tree
* blocks, we still need to trace the original subtrees.
*
* So for balance, we use a delayed subtree tracing, whose workflow is:
*
* 1) Record the subtree root block get swapped.
*
* During subtree swap:
* O = Old tree blocks
* N = New tree blocks
* reloc tree subvolume tree X
* Root Root
* / \ / \
* NA OB OA OB
* / | | \ / | | \
* NC ND OE OF OC OD OE OF
*
* In this case, NA and OA are going to be swapped, record (NA, OA) into
* subvolume tree X.
*
* 2) After subtree swap.
* reloc tree subvolume tree X
* Root Root
* / \ / \
* OA OB NA OB
* / | | \ / | | \
* OC OD OE OF NC ND OE OF
*
* 3a) COW happens for OB
* If we are going to COW tree block OB, we check OB's bytenr against
* tree X's swapped_blocks structure.
* If it doesn't fit any, nothing will happen.
*
* 3b) COW happens for NA
* Check NA's bytenr against tree X's swapped_blocks, and get a hit.
* Then we do subtree scan on both subtrees OA and NA.
* Resulting 6 tree blocks to be scanned (OA, OC, OD, NA, NC, ND).
*
* Then no matter what we do to subvolume tree X, qgroup numbers will
* still be correct.
* Then NA's record gets removed from X's swapped_blocks.
*
* 4) Transaction commit
* Any record in X's swapped_blocks gets removed, since there is no
* modification to the swapped subtrees, no need to trigger heavy qgroup
* subtree rescan for them.
*/
/*
* Record a dirty extent, and info qgroup to update quota on it
* TODO: Use kmem cache to alloc it.
*/
struct btrfs_qgroup_extent_record {
struct rb_node node;
u64 bytenr;
u64 num_bytes;
/*
* For qgroup reserved data space freeing.
*
* @data_rsv_refroot and @data_rsv will be recorded after
* BTRFS_ADD_DELAYED_EXTENT is called.
* And will be used to free reserved qgroup space at
* transaction commit time.
*/
u32 data_rsv; /* reserved data space needs to be freed */
u64 data_rsv_refroot; /* which root the reserved data belongs to */
struct ulist *old_roots;
};
struct btrfs_qgroup_swapped_block {
struct rb_node node;
int level;
bool trace_leaf;
/* bytenr/generation of the tree block in subvolume tree after swap */
u64 subvol_bytenr;
u64 subvol_generation;
/* bytenr/generation of the tree block in reloc tree after swap */
u64 reloc_bytenr;
u64 reloc_generation;
u64 last_snapshot;
struct btrfs_key first_key;
};
/*
* Qgroup reservation types:
*
* DATA:
* space reserved for data
*
* META_PERTRANS:
* Space reserved for metadata (per-transaction)
* Due to the fact that qgroup data is only updated at transaction commit
* time, reserved space for metadata must be kept until transaction
* commits.
* Any metadata reserved that are used in btrfs_start_transaction() should
* be of this type.
*
* META_PREALLOC:
* There are cases where metadata space is reserved before starting
* transaction, and then btrfs_join_transaction() to get a trans handle.
* Any metadata reserved for such usage should be of this type.
* And after join_transaction() part (or all) of such reservation should
* be converted into META_PERTRANS.
*/
enum btrfs_qgroup_rsv_type {
BTRFS_QGROUP_RSV_DATA,
BTRFS_QGROUP_RSV_META_PERTRANS,
BTRFS_QGROUP_RSV_META_PREALLOC,
BTRFS_QGROUP_RSV_LAST,
};
/*
* Represents how many bytes we have reserved for this qgroup.
*
* Each type should have different reservation behavior.
* E.g, data follows its io_tree flag modification, while
* *currently* meta is just reserve-and-clear during transaction.
*
* TODO: Add new type for reservation which can survive transaction commit.
* Current metadata reservation behavior is not suitable for such case.
*/
struct btrfs_qgroup_rsv {
u64 values[BTRFS_QGROUP_RSV_LAST];
};
/*
* one struct for each qgroup, organized in fs_info->qgroup_tree.
*/
struct btrfs_qgroup {
u64 qgroupid;
/*
* state
*/
u64 rfer; /* referenced */
u64 rfer_cmpr; /* referenced compressed */
u64 excl; /* exclusive */
u64 excl_cmpr; /* exclusive compressed */
/*
* limits
*/
u64 lim_flags; /* which limits are set */
u64 max_rfer;
u64 max_excl;
u64 rsv_rfer;
u64 rsv_excl;
/*
* reservation tracking
*/
struct btrfs_qgroup_rsv rsv;
/*
* lists
*/
struct list_head groups; /* groups this group is member of */
struct list_head members; /* groups that are members of this group */
struct list_head dirty; /* dirty groups */
struct rb_node node; /* tree of qgroups */
/*
* temp variables for accounting operations
* Refer to qgroup_shared_accounting() for details.
*/
u64 old_refcnt;
u64 new_refcnt;
/*
* Sysfs kobjectid
*/
struct kobject kobj;
};
static inline u64 btrfs_qgroup_subvolid(u64 qgroupid)
{
return (qgroupid & ((1ULL << BTRFS_QGROUP_LEVEL_SHIFT) - 1));
}
/*
* For qgroup event trace points only
*/
#define QGROUP_RESERVE (1<<0)
#define QGROUP_RELEASE (1<<1)
#define QGROUP_FREE (1<<2)
int btrfs_quota_enable(struct btrfs_fs_info *fs_info);
int btrfs_quota_disable(struct btrfs_fs_info *fs_info);
int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);
int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
bool interruptible);
int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
u64 dst);
int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
u64 dst);
int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);
int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);
int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid,
struct btrfs_qgroup_limit *limit);
int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info);
void btrfs_free_qgroup_config(struct btrfs_fs_info *fs_info);
struct btrfs_delayed_extent_op;
/*
* Inform qgroup to trace one dirty extent, its info is recorded in @record.
* So qgroup can account it at transaction committing time.
*
* No lock version, caller must acquire delayed ref lock and allocated memory,
* then call btrfs_qgroup_trace_extent_post() after exiting lock context.
*
* Return 0 for success insert
* Return >0 for existing record, caller can free @record safely.
* Error is not possible
*/
int btrfs_qgroup_trace_extent_nolock(
struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_qgroup_extent_record *record);
/*
* Post handler after qgroup_trace_extent_nolock().
*
* NOTE: Current qgroup does the expensive backref walk at transaction
* committing time with TRANS_STATE_COMMIT_DOING, this blocks incoming
* new transaction.
* This is designed to allow btrfs_find_all_roots() to get correct new_roots
* result.
*
* However for old_roots there is no need to do backref walk at that time,
* since we search commit roots to walk backref and result will always be
* correct.
*
* Due to the nature of no lock version, we can't do backref there.
* So we must call btrfs_qgroup_trace_extent_post() after exiting
* spinlock context.
*
* TODO: If we can fix and prove btrfs_find_all_roots() can get correct result
* using current root, then we can move all expensive backref walk out of
* transaction committing, but not now as qgroup accounting will be wrong again.
*/
int btrfs_qgroup_trace_extent_post(struct btrfs_trans_handle *trans,
struct btrfs_qgroup_extent_record *qrecord);
/*
* Inform qgroup to trace one dirty extent, specified by @bytenr and
* @num_bytes.
* So qgroup can account it at commit trans time.
*
* Better encapsulated version, with memory allocation and backref walk for
* commit roots.
* So this can sleep.
*
* Return 0 if the operation is done.
* Return <0 for error, like memory allocation failure or invalid parameter
* (NULL trans)
*/
int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
u64 num_bytes, gfp_t gfp_flag);
/*
* Inform qgroup to trace all leaf items of data
*
* Return 0 for success
* Return <0 for error(ENOMEM)
*/
int btrfs_qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,
struct extent_buffer *eb);
/*
* Inform qgroup to trace a whole subtree, including all its child tree
* blocks and data.
* The root tree block is specified by @root_eb.
*
* Normally used by relocation(tree block swap) and subvolume deletion.
*
* Return 0 for success
* Return <0 for error(ENOMEM or tree search error)
*/
int btrfs_qgroup_trace_subtree(struct btrfs_trans_handle *trans,
struct extent_buffer *root_eb,
u64 root_gen, int root_level);
int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
u64 num_bytes, struct ulist *old_roots,
struct ulist *new_roots);
int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans);
int btrfs_run_qgroups(struct btrfs_trans_handle *trans);
int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
u64 objectid, struct btrfs_qgroup_inherit *inherit);
void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
u64 ref_root, u64 num_bytes,
enum btrfs_qgroup_rsv_type type);
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
int btrfs_verify_qgroup_counts(struct btrfs_fs_info *fs_info, u64 qgroupid,
u64 rfer, u64 excl);
#endif
/* New io_tree based accurate qgroup reserve API */
int btrfs_qgroup_reserve_data(struct btrfs_inode *inode,
struct extent_changeset **reserved, u64 start, u64 len);
int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len);
int btrfs_qgroup_free_data(struct btrfs_inode *inode,
struct extent_changeset *reserved, u64 start,
u64 len);
int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
enum btrfs_qgroup_rsv_type type, bool enforce);
int __btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
enum btrfs_qgroup_rsv_type type, bool enforce,
bool noflush);
/* Reserve metadata space for pertrans and prealloc type */
static inline int btrfs_qgroup_reserve_meta_pertrans(struct btrfs_root *root,
int num_bytes, bool enforce)
{
return __btrfs_qgroup_reserve_meta(root, num_bytes,
BTRFS_QGROUP_RSV_META_PERTRANS,
enforce, false);
}
static inline int btrfs_qgroup_reserve_meta_prealloc(struct btrfs_root *root,
int num_bytes, bool enforce,
bool noflush)
{
return __btrfs_qgroup_reserve_meta(root, num_bytes,
BTRFS_QGROUP_RSV_META_PREALLOC,
enforce, noflush);
}
void __btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes,
enum btrfs_qgroup_rsv_type type);
/* Free per-transaction meta reservation for error handling */
static inline void btrfs_qgroup_free_meta_pertrans(struct btrfs_root *root,
int num_bytes)
{
__btrfs_qgroup_free_meta(root, num_bytes,
BTRFS_QGROUP_RSV_META_PERTRANS);
}
/* Pre-allocated meta reservation can be freed at need */
static inline void btrfs_qgroup_free_meta_prealloc(struct btrfs_root *root,
int num_bytes)
{
__btrfs_qgroup_free_meta(root, num_bytes,
BTRFS_QGROUP_RSV_META_PREALLOC);
}
/*
* Per-transaction meta reservation should be all freed at transaction commit
* time
*/
void btrfs_qgroup_free_meta_all_pertrans(struct btrfs_root *root);
/*
* Convert @num_bytes of META_PREALLOCATED reservation to META_PERTRANS.
*
* This is called when preallocated meta reservation needs to be used.
* Normally after btrfs_join_transaction() call.
*/
void btrfs_qgroup_convert_reserved_meta(struct btrfs_root *root, int num_bytes);
void btrfs_qgroup_check_reserved_leak(struct btrfs_inode *inode);
/* btrfs_qgroup_swapped_blocks related functions */
void btrfs_qgroup_init_swapped_blocks(
struct btrfs_qgroup_swapped_blocks *swapped_blocks);
void btrfs_qgroup_clean_swapped_blocks(struct btrfs_root *root);
int btrfs_qgroup_add_swapped_blocks(struct btrfs_trans_handle *trans,
struct btrfs_root *subvol_root,
struct btrfs_block_group *bg,
struct extent_buffer *subvol_parent, int subvol_slot,
struct extent_buffer *reloc_parent, int reloc_slot,
u64 last_snapshot);
int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *eb);
void btrfs_qgroup_destroy_extent_records(struct btrfs_transaction *trans);
bool btrfs_check_quota_leak(struct btrfs_fs_info *fs_info);
#endif