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![Filipe Manana](/assets/img/avatar_default.png)
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>
437 lines
14 KiB
C
437 lines
14 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2014 Facebook. All rights reserved.
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*/
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#ifndef BTRFS_QGROUP_H
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#define BTRFS_QGROUP_H
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#include <linux/spinlock.h>
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#include <linux/rbtree.h>
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#include <linux/kobject.h>
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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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* Special performance optimization for balance.
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*
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* For balance, we need to swap subtree of subvolume and reloc trees.
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* In theory, we need to trace all subtree blocks of both subvolume and reloc
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* trees, since their owner has changed during such swap.
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*
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* However since balance has ensured that both subtrees are containing the
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* same contents and have the same tree structures, such swap won't cause
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* qgroup number change.
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*
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* But there is a race window between subtree swap and transaction commit,
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* during that window, if we increase/decrease tree level or merge/split tree
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* blocks, we still need to trace the original subtrees.
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*
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* So for balance, we use a delayed subtree tracing, whose workflow is:
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*
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* 1) Record the subtree root block get swapped.
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*
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* During subtree swap:
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* O = Old tree blocks
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* N = New tree blocks
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* reloc tree subvolume tree X
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* Root Root
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* / \ / \
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* NA OB OA OB
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* / | | \ / | | \
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* NC ND OE OF OC OD OE OF
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*
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* In this case, NA and OA are going to be swapped, record (NA, OA) into
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* subvolume tree X.
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*
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* 2) After subtree swap.
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* reloc tree subvolume tree X
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* Root Root
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* / \ / \
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* OA OB NA OB
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* / | | \ / | | \
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* OC OD OE OF NC ND OE OF
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*
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* 3a) COW happens for OB
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* If we are going to COW tree block OB, we check OB's bytenr against
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* tree X's swapped_blocks structure.
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* If it doesn't fit any, nothing will happen.
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*
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* 3b) COW happens for NA
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* Check NA's bytenr against tree X's swapped_blocks, and get a hit.
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* Then we do subtree scan on both subtrees OA and NA.
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* Resulting 6 tree blocks to be scanned (OA, OC, OD, NA, NC, ND).
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*
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* Then no matter what we do to subvolume tree X, qgroup numbers will
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* still be correct.
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* Then NA's record gets removed from X's swapped_blocks.
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*
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* 4) Transaction commit
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* Any record in X's swapped_blocks gets removed, since there is no
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* modification to the swapped subtrees, no need to trigger heavy qgroup
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* subtree rescan for them.
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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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/*
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* For qgroup reserved data space freeing.
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*
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* @data_rsv_refroot and @data_rsv will be recorded after
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* BTRFS_ADD_DELAYED_EXTENT is called.
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* And will be used to free reserved qgroup space at
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* transaction commit time.
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*/
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u32 data_rsv; /* reserved data space needs to be freed */
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u64 data_rsv_refroot; /* which root the reserved data belongs to */
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struct ulist *old_roots;
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};
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struct btrfs_qgroup_swapped_block {
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struct rb_node node;
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int level;
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bool trace_leaf;
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/* bytenr/generation of the tree block in subvolume tree after swap */
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u64 subvol_bytenr;
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u64 subvol_generation;
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/* bytenr/generation of the tree block in reloc tree after swap */
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u64 reloc_bytenr;
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u64 reloc_generation;
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u64 last_snapshot;
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struct btrfs_key first_key;
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};
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/*
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* Qgroup reservation types:
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*
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* DATA:
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* space reserved for data
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*
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* META_PERTRANS:
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* Space reserved for metadata (per-transaction)
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* Due to the fact that qgroup data is only updated at transaction commit
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* time, reserved space for metadata must be kept until transaction
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* commits.
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* Any metadata reserved that are used in btrfs_start_transaction() should
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* be of this type.
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*
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* META_PREALLOC:
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* There are cases where metadata space is reserved before starting
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* transaction, and then btrfs_join_transaction() to get a trans handle.
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* Any metadata reserved for such usage should be of this type.
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* And after join_transaction() part (or all) of such reservation should
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* be converted into META_PERTRANS.
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*/
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enum btrfs_qgroup_rsv_type {
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BTRFS_QGROUP_RSV_DATA,
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BTRFS_QGROUP_RSV_META_PERTRANS,
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BTRFS_QGROUP_RSV_META_PREALLOC,
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BTRFS_QGROUP_RSV_LAST,
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};
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/*
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* Represents how many bytes we have reserved for this qgroup.
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*
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* Each type should have different reservation behavior.
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* E.g, data follows its io_tree flag modification, while
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* *currently* meta is just reserve-and-clear during transaction.
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*
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* TODO: Add new type for reservation which can survive transaction commit.
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* Current metadata reservation behavior is not suitable for such case.
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*/
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struct btrfs_qgroup_rsv {
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u64 values[BTRFS_QGROUP_RSV_LAST];
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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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struct btrfs_qgroup_rsv rsv;
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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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* Sysfs kobjectid
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*/
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struct kobject kobj;
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};
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static inline u64 btrfs_qgroup_subvolid(u64 qgroupid)
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{
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return (qgroupid & ((1ULL << BTRFS_QGROUP_LEVEL_SHIFT) - 1));
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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_fs_info *fs_info);
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int btrfs_quota_disable(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, u64 src,
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u64 dst);
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int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
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u64 dst);
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int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);
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int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);
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int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, 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_trans_handle *trans,
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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, u64 bytenr,
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u64 num_bytes, 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 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 extent_buffer *root_eb,
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u64 root_gen, int root_level);
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int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
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u64 num_bytes, struct ulist *old_roots,
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struct ulist *new_roots);
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int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans);
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int btrfs_run_qgroups(struct btrfs_trans_handle *trans);
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int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
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u64 objectid, 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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enum btrfs_qgroup_rsv_type type);
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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 btrfs_inode *inode,
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struct extent_changeset **reserved, u64 start, u64 len);
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int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len);
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int btrfs_qgroup_free_data(struct btrfs_inode *inode,
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struct extent_changeset *reserved, u64 start,
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u64 len);
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int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
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enum btrfs_qgroup_rsv_type type, bool enforce);
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int __btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
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enum btrfs_qgroup_rsv_type type, bool enforce,
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bool noflush);
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/* Reserve metadata space for pertrans and prealloc type */
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static inline int btrfs_qgroup_reserve_meta_pertrans(struct btrfs_root *root,
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int num_bytes, bool enforce)
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{
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return __btrfs_qgroup_reserve_meta(root, num_bytes,
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BTRFS_QGROUP_RSV_META_PERTRANS,
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enforce, false);
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}
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static inline int btrfs_qgroup_reserve_meta_prealloc(struct btrfs_root *root,
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int num_bytes, bool enforce,
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bool noflush)
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{
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return __btrfs_qgroup_reserve_meta(root, num_bytes,
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BTRFS_QGROUP_RSV_META_PREALLOC,
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enforce, noflush);
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}
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void __btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes,
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enum btrfs_qgroup_rsv_type type);
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/* Free per-transaction meta reservation for error handling */
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static inline void btrfs_qgroup_free_meta_pertrans(struct btrfs_root *root,
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int num_bytes)
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{
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__btrfs_qgroup_free_meta(root, num_bytes,
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BTRFS_QGROUP_RSV_META_PERTRANS);
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}
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/* Pre-allocated meta reservation can be freed at need */
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static inline void btrfs_qgroup_free_meta_prealloc(struct btrfs_root *root,
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int num_bytes)
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{
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__btrfs_qgroup_free_meta(root, num_bytes,
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BTRFS_QGROUP_RSV_META_PREALLOC);
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}
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/*
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* Per-transaction meta reservation should be all freed at transaction commit
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* time
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*/
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void btrfs_qgroup_free_meta_all_pertrans(struct btrfs_root *root);
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/*
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* Convert @num_bytes of META_PREALLOCATED reservation to META_PERTRANS.
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*
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* This is called when preallocated meta reservation needs to be used.
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* Normally after btrfs_join_transaction() call.
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*/
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void btrfs_qgroup_convert_reserved_meta(struct btrfs_root *root, int num_bytes);
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void btrfs_qgroup_check_reserved_leak(struct btrfs_inode *inode);
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/* btrfs_qgroup_swapped_blocks related functions */
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void btrfs_qgroup_init_swapped_blocks(
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struct btrfs_qgroup_swapped_blocks *swapped_blocks);
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void btrfs_qgroup_clean_swapped_blocks(struct btrfs_root *root);
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int btrfs_qgroup_add_swapped_blocks(struct btrfs_trans_handle *trans,
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struct btrfs_root *subvol_root,
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struct btrfs_block_group *bg,
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struct extent_buffer *subvol_parent, int subvol_slot,
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struct extent_buffer *reloc_parent, int reloc_slot,
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u64 last_snapshot);
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int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, struct extent_buffer *eb);
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void btrfs_qgroup_destroy_extent_records(struct btrfs_transaction *trans);
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bool btrfs_check_quota_leak(struct btrfs_fs_info *fs_info);
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#endif
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