| Message ID | 920701be19f36b4f7ed84efd53a3d0550700f047.1618494550.git.johannes.thumshirn@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: zoned: automatic BG reclaim | expand |
On 4/15/21 9:58 AM, Johannes Thumshirn wrote: > When a file gets deleted on a zoned file system, the space freed is not > returned back into the block group's free space, but is migrated to > zone_unusable. > > As this zone_unusable space is behind the current write pointer it is not > possible to use it for new allocations. In the current implementation a > zone is reset once all of the block group's space is accounted as zone > unusable. > > This behaviour can lead to premature ENOSPC errors on a busy file system. > > Instead of only reclaiming the zone once it is completely unusable, > kick off a reclaim job once the amount of unusable bytes exceeds a user > configurable threshold between 51% and 100%. It can be set per mounted > filesystem via the sysfs tunable bg_reclaim_threshold which is set to 75% > per default. > > Similar to reclaiming unused block groups, these dirty block groups are > added to a to_reclaim list and then on a transaction commit, the reclaim > process is triggered but after we deleted unused block groups, which will > free space for the relocation process. > > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> > --- > fs/btrfs/block-group.c | 96 ++++++++++++++++++++++++++++++++++++ > fs/btrfs/block-group.h | 3 ++ > fs/btrfs/ctree.h | 6 +++ > fs/btrfs/disk-io.c | 13 +++++ > fs/btrfs/free-space-cache.c | 9 +++- > fs/btrfs/sysfs.c | 35 +++++++++++++ > fs/btrfs/volumes.c | 2 +- > fs/btrfs/volumes.h | 1 + > include/trace/events/btrfs.h | 12 +++++ > 9 files changed, 175 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c > index bbb5a6e170c7..3f06ea42c013 100644 > --- a/fs/btrfs/block-group.c > +++ b/fs/btrfs/block-group.c > @@ -1485,6 +1485,92 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg) > spin_unlock(&fs_info->unused_bgs_lock); > } > > +void btrfs_reclaim_bgs_work(struct work_struct *work) > +{ > + struct btrfs_fs_info *fs_info = > + container_of(work, struct btrfs_fs_info, reclaim_bgs_work); > + struct btrfs_block_group *bg; > + struct btrfs_space_info *space_info; > + int ret = 0; > + > + if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags)) > + return; > + > + if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) > + return; > + > + mutex_lock(&fs_info->reclaim_bgs_lock); > + spin_lock(&fs_info->unused_bgs_lock); > + while (!list_empty(&fs_info->reclaim_bgs)) { > + bg = list_first_entry(&fs_info->reclaim_bgs, > + struct btrfs_block_group, > + bg_list); > + list_del_init(&bg->bg_list); > + > + space_info = bg->space_info; > + spin_unlock(&fs_info->unused_bgs_lock); > + > + /* Don't want to race with allocators so take the groups_sem */ > + down_write(&space_info->groups_sem); > + > + spin_lock(&bg->lock); > + if (bg->reserved || bg->pinned || bg->ro) { > + /* > + * We want to bail if we made new allocations or have > + * outstanding allocations in this block group. We do > + * the ro check in case balance is currently acting on > + * this block group. > + */ > + spin_unlock(&bg->lock); > + up_write(&space_info->groups_sem); > + goto next; > + } > + spin_unlock(&bg->lock); > + Here I think we want a if (btrfs_fs_closing()) goto next; so we don't block out a umount for all eternity. Thanks, Josef
On 15/04/2021 20:37, Josef Bacik wrote: > On 4/15/21 9:58 AM, Johannes Thumshirn wrote: >> When a file gets deleted on a zoned file system, the space freed is not >> returned back into the block group's free space, but is migrated to >> zone_unusable. >> >> As this zone_unusable space is behind the current write pointer it is not >> possible to use it for new allocations. In the current implementation a >> zone is reset once all of the block group's space is accounted as zone >> unusable. >> >> This behaviour can lead to premature ENOSPC errors on a busy file system. >> >> Instead of only reclaiming the zone once it is completely unusable, >> kick off a reclaim job once the amount of unusable bytes exceeds a user >> configurable threshold between 51% and 100%. It can be set per mounted >> filesystem via the sysfs tunable bg_reclaim_threshold which is set to 75% >> per default. >> >> Similar to reclaiming unused block groups, these dirty block groups are >> added to a to_reclaim list and then on a transaction commit, the reclaim >> process is triggered but after we deleted unused block groups, which will >> free space for the relocation process. >> >> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> >> --- >> fs/btrfs/block-group.c | 96 ++++++++++++++++++++++++++++++++++++ >> fs/btrfs/block-group.h | 3 ++ >> fs/btrfs/ctree.h | 6 +++ >> fs/btrfs/disk-io.c | 13 +++++ >> fs/btrfs/free-space-cache.c | 9 +++- >> fs/btrfs/sysfs.c | 35 +++++++++++++ >> fs/btrfs/volumes.c | 2 +- >> fs/btrfs/volumes.h | 1 + >> include/trace/events/btrfs.h | 12 +++++ >> 9 files changed, 175 insertions(+), 2 deletions(-) >> >> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c >> index bbb5a6e170c7..3f06ea42c013 100644 >> --- a/fs/btrfs/block-group.c >> +++ b/fs/btrfs/block-group.c >> @@ -1485,6 +1485,92 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg) >> spin_unlock(&fs_info->unused_bgs_lock); >> } >> >> +void btrfs_reclaim_bgs_work(struct work_struct *work) >> +{ >> + struct btrfs_fs_info *fs_info = >> + container_of(work, struct btrfs_fs_info, reclaim_bgs_work); >> + struct btrfs_block_group *bg; >> + struct btrfs_space_info *space_info; >> + int ret = 0; >> + >> + if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags)) >> + return; >> + >> + if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) >> + return; >> + >> + mutex_lock(&fs_info->reclaim_bgs_lock); >> + spin_lock(&fs_info->unused_bgs_lock); >> + while (!list_empty(&fs_info->reclaim_bgs)) { >> + bg = list_first_entry(&fs_info->reclaim_bgs, >> + struct btrfs_block_group, >> + bg_list); >> + list_del_init(&bg->bg_list); >> + >> + space_info = bg->space_info; >> + spin_unlock(&fs_info->unused_bgs_lock); >> + >> + /* Don't want to race with allocators so take the groups_sem */ >> + down_write(&space_info->groups_sem); >> + >> + spin_lock(&bg->lock); >> + if (bg->reserved || bg->pinned || bg->ro) { >> + /* >> + * We want to bail if we made new allocations or have >> + * outstanding allocations in this block group. We do >> + * the ro check in case balance is currently acting on >> + * this block group. >> + */ >> + spin_unlock(&bg->lock); >> + up_write(&space_info->groups_sem); >> + goto next; >> + } >> + spin_unlock(&bg->lock); >> + > > Here I think we want a > > if (btrfs_fs_closing()) > goto next; > > so we don't block out a umount for all eternity. Thanks, Right, will add.
On Thu, Apr 15, 2021 at 3:00 PM Johannes Thumshirn <johannes.thumshirn@wdc.com> wrote: > > When a file gets deleted on a zoned file system, the space freed is not > returned back into the block group's free space, but is migrated to > zone_unusable. > > As this zone_unusable space is behind the current write pointer it is not > possible to use it for new allocations. In the current implementation a > zone is reset once all of the block group's space is accounted as zone > unusable. > > This behaviour can lead to premature ENOSPC errors on a busy file system. > > Instead of only reclaiming the zone once it is completely unusable, > kick off a reclaim job once the amount of unusable bytes exceeds a user > configurable threshold between 51% and 100%. It can be set per mounted > filesystem via the sysfs tunable bg_reclaim_threshold which is set to 75% > per default. > > Similar to reclaiming unused block groups, these dirty block groups are > added to a to_reclaim list and then on a transaction commit, the reclaim > process is triggered but after we deleted unused block groups, which will > free space for the relocation process. > > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> > --- > fs/btrfs/block-group.c | 96 ++++++++++++++++++++++++++++++++++++ > fs/btrfs/block-group.h | 3 ++ > fs/btrfs/ctree.h | 6 +++ > fs/btrfs/disk-io.c | 13 +++++ > fs/btrfs/free-space-cache.c | 9 +++- > fs/btrfs/sysfs.c | 35 +++++++++++++ > fs/btrfs/volumes.c | 2 +- > fs/btrfs/volumes.h | 1 + > include/trace/events/btrfs.h | 12 +++++ > 9 files changed, 175 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c > index bbb5a6e170c7..3f06ea42c013 100644 > --- a/fs/btrfs/block-group.c > +++ b/fs/btrfs/block-group.c > @@ -1485,6 +1485,92 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg) > spin_unlock(&fs_info->unused_bgs_lock); > } > > +void btrfs_reclaim_bgs_work(struct work_struct *work) > +{ > + struct btrfs_fs_info *fs_info = > + container_of(work, struct btrfs_fs_info, reclaim_bgs_work); > + struct btrfs_block_group *bg; > + struct btrfs_space_info *space_info; > + int ret = 0; > + > + if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags)) > + return; > + > + if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) > + return; > + > + mutex_lock(&fs_info->reclaim_bgs_lock); > + spin_lock(&fs_info->unused_bgs_lock); > + while (!list_empty(&fs_info->reclaim_bgs)) { > + bg = list_first_entry(&fs_info->reclaim_bgs, > + struct btrfs_block_group, > + bg_list); > + list_del_init(&bg->bg_list); > + > + space_info = bg->space_info; > + spin_unlock(&fs_info->unused_bgs_lock); > + > + /* Don't want to race with allocators so take the groups_sem */ > + down_write(&space_info->groups_sem); > + > + spin_lock(&bg->lock); > + if (bg->reserved || bg->pinned || bg->ro) { > + /* > + * We want to bail if we made new allocations or have > + * outstanding allocations in this block group. We do > + * the ro check in case balance is currently acting on > + * this block group. > + */ > + spin_unlock(&bg->lock); > + up_write(&space_info->groups_sem); > + goto next; > + } > + spin_unlock(&bg->lock); > + > + ret = inc_block_group_ro(bg, 0); > + up_write(&space_info->groups_sem); > + if (ret < 0) { > + ret = 0; It's pointless to set ret to 0. > + goto next; > + } > + > + btrfs_info(fs_info, "reclaiming chunk %llu", bg->start); > + trace_btrfs_reclaim_block_group(bg); > + ret = btrfs_relocate_chunk(fs_info, bg->start); > + if (ret) > + btrfs_err(fs_info, "error relocating chunk %llu", > + bg->start); > + > +next: > + btrfs_put_block_group(bg); > + spin_lock(&fs_info->unused_bgs_lock); > + } > + spin_unlock(&fs_info->unused_bgs_lock); > + mutex_unlock(&fs_info->reclaim_bgs_lock); > + btrfs_exclop_finish(fs_info); > +} > + > +void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info) > +{ > + spin_lock(&fs_info->unused_bgs_lock); > + if (!list_empty(&fs_info->reclaim_bgs)) > + queue_work(system_unbound_wq, &fs_info->reclaim_bgs_work); > + spin_unlock(&fs_info->unused_bgs_lock); > +} > + > +void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg) > +{ > + struct btrfs_fs_info *fs_info = bg->fs_info; > + > + spin_lock(&fs_info->unused_bgs_lock); > + if (list_empty(&bg->bg_list)) { > + btrfs_get_block_group(bg); > + trace_btrfs_add_reclaim_block_group(bg); > + list_add_tail(&bg->bg_list, &fs_info->reclaim_bgs); > + } > + spin_unlock(&fs_info->unused_bgs_lock); > +} > + > static int read_bg_from_eb(struct btrfs_fs_info *fs_info, struct btrfs_key *key, > struct btrfs_path *path) > { > @@ -3446,6 +3532,16 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info) > } > spin_unlock(&info->unused_bgs_lock); > > + spin_lock(&info->unused_bgs_lock); > + while (!list_empty(&info->reclaim_bgs)) { > + block_group = list_first_entry(&info->reclaim_bgs, > + struct btrfs_block_group, > + bg_list); > + list_del_init(&block_group->bg_list); > + btrfs_put_block_group(block_group); > + } > + spin_unlock(&info->unused_bgs_lock); > + > spin_lock(&info->block_group_cache_lock); > while ((n = rb_last(&info->block_group_cache_tree)) != NULL) { > block_group = rb_entry(n, struct btrfs_block_group, > diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h > index 3ecc3372a5ce..7b927425dc71 100644 > --- a/fs/btrfs/block-group.h > +++ b/fs/btrfs/block-group.h > @@ -264,6 +264,9 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans, > u64 group_start, struct extent_map *em); > void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info); > void btrfs_mark_bg_unused(struct btrfs_block_group *bg); > +void btrfs_reclaim_bgs_work(struct work_struct *work); > +void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info); > +void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg); > int btrfs_read_block_groups(struct btrfs_fs_info *info); > int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used, > u64 type, u64 chunk_offset, u64 size); > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > index c80302564e6b..88531c1fbcdf 100644 > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -954,10 +954,14 @@ struct btrfs_fs_info { > struct work_struct async_data_reclaim_work; > struct work_struct preempt_reclaim_work; > > + /* Used to reclaim data space in the background */ Not just data, metadata block groups too. Perhaps saying it's used to reclaim partially filled block groups is more meaningful. Other than that it looks good. With Josef's suggestion to not slow down unmount too much, you can add Reviewed-by: Filipe Manana <fdmanana@suse.com> Thanks. > + struct work_struct reclaim_bgs_work; > + > spinlock_t unused_bgs_lock; > struct list_head unused_bgs; > struct mutex unused_bg_unpin_mutex; > struct mutex reclaim_bgs_lock; > + struct list_head reclaim_bgs; > > /* Cached block sizes */ > u32 nodesize; > @@ -998,6 +1002,8 @@ struct btrfs_fs_info { > spinlock_t treelog_bg_lock; > u64 treelog_bg; > > + int bg_reclaim_threshold; > + > #ifdef CONFIG_BTRFS_FS_REF_VERIFY > spinlock_t ref_verify_lock; > struct rb_root block_tree; > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index e52b89ad0a61..942d894ec175 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -1898,6 +1898,13 @@ static int cleaner_kthread(void *arg) > * unused block groups. > */ > btrfs_delete_unused_bgs(fs_info); > + > + /* > + * Reclaim block groups in the reclaim_bgs list after we deleted > + * all unused block_groups. This possibly gives us some more free > + * space. > + */ > + btrfs_reclaim_bgs(fs_info); > sleep: > clear_and_wake_up_bit(BTRFS_FS_CLEANER_RUNNING, &fs_info->flags); > if (kthread_should_park()) > @@ -2886,6 +2893,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) > INIT_LIST_HEAD(&fs_info->space_info); > INIT_LIST_HEAD(&fs_info->tree_mod_seq_list); > INIT_LIST_HEAD(&fs_info->unused_bgs); > + INIT_LIST_HEAD(&fs_info->reclaim_bgs); > #ifdef CONFIG_BTRFS_DEBUG > INIT_LIST_HEAD(&fs_info->allocated_roots); > INIT_LIST_HEAD(&fs_info->allocated_ebs); > @@ -2974,6 +2982,9 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) > fs_info->swapfile_pins = RB_ROOT; > > fs_info->send_in_progress = 0; > + > + fs_info->bg_reclaim_threshold = 75; > + INIT_WORK(&fs_info->reclaim_bgs_work, btrfs_reclaim_bgs_work); > } > > static int init_mount_fs_info(struct btrfs_fs_info *fs_info, struct super_block *sb) > @@ -4332,6 +4343,8 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info) > cancel_work_sync(&fs_info->async_data_reclaim_work); > cancel_work_sync(&fs_info->preempt_reclaim_work); > > + cancel_work_sync(&fs_info->reclaim_bgs_work); > + > /* Cancel or finish ongoing discard work */ > btrfs_discard_cleanup(fs_info); > > diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c > index 9988decd5717..e54466fc101f 100644 > --- a/fs/btrfs/free-space-cache.c > +++ b/fs/btrfs/free-space-cache.c > @@ -11,6 +11,7 @@ > #include <linux/ratelimit.h> > #include <linux/error-injection.h> > #include <linux/sched/mm.h> > +#include "misc.h" > #include "ctree.h" > #include "free-space-cache.h" > #include "transaction.h" > @@ -2539,6 +2540,7 @@ int __btrfs_add_free_space(struct btrfs_fs_info *fs_info, > static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, > u64 bytenr, u64 size, bool used) > { > + struct btrfs_fs_info *fs_info = block_group->fs_info; > struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; > u64 offset = bytenr - block_group->start; > u64 to_free, to_unusable; > @@ -2569,8 +2571,13 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, > } > > /* All the region is now unusable. Mark it as unused and reclaim */ > - if (block_group->zone_unusable == block_group->length) > + if (block_group->zone_unusable == block_group->length) { > btrfs_mark_bg_unused(block_group); > + } else if (block_group->zone_unusable >= > + div_factor_fine(block_group->length, > + fs_info->bg_reclaim_threshold)) { > + btrfs_mark_bg_to_reclaim(block_group); > + } > > return 0; > } > diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c > index a99d1f415a7f..436ac7b4b334 100644 > --- a/fs/btrfs/sysfs.c > +++ b/fs/btrfs/sysfs.c > @@ -980,6 +980,40 @@ static ssize_t btrfs_read_policy_store(struct kobject *kobj, > } > BTRFS_ATTR_RW(, read_policy, btrfs_read_policy_show, btrfs_read_policy_store); > > +static ssize_t btrfs_bg_reclaim_threshold_show(struct kobject *kobj, > + struct kobj_attribute *a, > + char *buf) > +{ > + struct btrfs_fs_info *fs_info = to_fs_info(kobj); > + ssize_t ret; > + > + ret = scnprintf(buf, PAGE_SIZE, "%d\n", fs_info->bg_reclaim_threshold); > + > + return ret; > +} > + > +static ssize_t btrfs_bg_reclaim_threshold_store(struct kobject *kobj, > + struct kobj_attribute *a, > + const char *buf, size_t len) > +{ > + struct btrfs_fs_info *fs_info = to_fs_info(kobj); > + int thresh; > + int ret; > + > + ret = kstrtoint(buf, 10, &thresh); > + if (ret) > + return ret; > + > + if (thresh <= 50 || thresh > 100) > + return -EINVAL; > + > + fs_info->bg_reclaim_threshold = thresh; > + > + return len; > +} > +BTRFS_ATTR_RW(, bg_reclaim_threshold, btrfs_bg_reclaim_threshold_show, > + btrfs_bg_reclaim_threshold_store); > + > static const struct attribute *btrfs_attrs[] = { > BTRFS_ATTR_PTR(, label), > BTRFS_ATTR_PTR(, nodesize), > @@ -991,6 +1025,7 @@ static const struct attribute *btrfs_attrs[] = { > BTRFS_ATTR_PTR(, exclusive_operation), > BTRFS_ATTR_PTR(, generation), > BTRFS_ATTR_PTR(, read_policy), > + BTRFS_ATTR_PTR(, bg_reclaim_threshold), > NULL, > }; > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index a2a7f5ab0a3e..527324154e3e 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -3098,7 +3098,7 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset) > return ret; > } > > -static int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) > +int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) > { > struct btrfs_root *root = fs_info->chunk_root; > struct btrfs_trans_handle *trans; > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h > index d4c3e0dd32b8..9c0d84e5ec06 100644 > --- a/fs/btrfs/volumes.h > +++ b/fs/btrfs/volumes.h > @@ -484,6 +484,7 @@ void btrfs_describe_block_groups(u64 flags, char *buf, u32 size_buf); > int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info); > int btrfs_recover_balance(struct btrfs_fs_info *fs_info); > int btrfs_pause_balance(struct btrfs_fs_info *fs_info); > +int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset); > int btrfs_cancel_balance(struct btrfs_fs_info *fs_info); > int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info); > int btrfs_uuid_scan_kthread(void *data); > diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h > index 0551ea65374f..a41dd8a0c730 100644 > --- a/include/trace/events/btrfs.h > +++ b/include/trace/events/btrfs.h > @@ -1903,6 +1903,18 @@ DEFINE_EVENT(btrfs__block_group, btrfs_add_unused_block_group, > TP_ARGS(bg_cache) > ); > > +DEFINE_EVENT(btrfs__block_group, btrfs_add_reclaim_block_group, > + TP_PROTO(const struct btrfs_block_group *bg_cache), > + > + TP_ARGS(bg_cache) > +); > + > +DEFINE_EVENT(btrfs__block_group, btrfs_reclaim_block_group, > + TP_PROTO(const struct btrfs_block_group *bg_cache), > + > + TP_ARGS(bg_cache) > +); > + > DEFINE_EVENT(btrfs__block_group, btrfs_skip_unused_block_group, > TP_PROTO(const struct btrfs_block_group *bg_cache), > > -- > 2.30.0 >
On Thu, Apr 15, 2021 at 10:58:35PM +0900, Johannes Thumshirn wrote: > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -954,10 +954,14 @@ struct btrfs_fs_info { > struct work_struct async_data_reclaim_work; > struct work_struct preempt_reclaim_work; > > + /* Used to reclaim data space in the background */ > + struct work_struct reclaim_bgs_work; > + > spinlock_t unused_bgs_lock; > struct list_head unused_bgs; > struct mutex unused_bg_unpin_mutex; > struct mutex reclaim_bgs_lock; > + struct list_head reclaim_bgs; > > /* Cached block sizes */ > u32 nodesize; > @@ -998,6 +1002,8 @@ struct btrfs_fs_info { > spinlock_t treelog_bg_lock; > u64 treelog_bg; > > + int bg_reclaim_threshold; That's spreading related members over too many lines, please put them together with comments what they mean if that's not obvious (like for the work struct).
On Thu, Apr 15, 2021 at 10:58:35PM +0900, Johannes Thumshirn wrote: > @@ -2974,6 +2982,9 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) > fs_info->swapfile_pins = RB_ROOT; > > fs_info->send_in_progress = 0; > + > + fs_info->bg_reclaim_threshold = 75; The value should be a named constant visible defined in zoned.h with a comment what it means.
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index bbb5a6e170c7..3f06ea42c013 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1485,6 +1485,92 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg) spin_unlock(&fs_info->unused_bgs_lock); } +void btrfs_reclaim_bgs_work(struct work_struct *work) +{ + struct btrfs_fs_info *fs_info = + container_of(work, struct btrfs_fs_info, reclaim_bgs_work); + struct btrfs_block_group *bg; + struct btrfs_space_info *space_info; + int ret = 0; + + if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags)) + return; + + if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) + return; + + mutex_lock(&fs_info->reclaim_bgs_lock); + spin_lock(&fs_info->unused_bgs_lock); + while (!list_empty(&fs_info->reclaim_bgs)) { + bg = list_first_entry(&fs_info->reclaim_bgs, + struct btrfs_block_group, + bg_list); + list_del_init(&bg->bg_list); + + space_info = bg->space_info; + spin_unlock(&fs_info->unused_bgs_lock); + + /* Don't want to race with allocators so take the groups_sem */ + down_write(&space_info->groups_sem); + + spin_lock(&bg->lock); + if (bg->reserved || bg->pinned || bg->ro) { + /* + * We want to bail if we made new allocations or have + * outstanding allocations in this block group. We do + * the ro check in case balance is currently acting on + * this block group. + */ + spin_unlock(&bg->lock); + up_write(&space_info->groups_sem); + goto next; + } + spin_unlock(&bg->lock); + + ret = inc_block_group_ro(bg, 0); + up_write(&space_info->groups_sem); + if (ret < 0) { + ret = 0; + goto next; + } + + btrfs_info(fs_info, "reclaiming chunk %llu", bg->start); + trace_btrfs_reclaim_block_group(bg); + ret = btrfs_relocate_chunk(fs_info, bg->start); + if (ret) + btrfs_err(fs_info, "error relocating chunk %llu", + bg->start); + +next: + btrfs_put_block_group(bg); + spin_lock(&fs_info->unused_bgs_lock); + } + spin_unlock(&fs_info->unused_bgs_lock); + mutex_unlock(&fs_info->reclaim_bgs_lock); + btrfs_exclop_finish(fs_info); +} + +void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info) +{ + spin_lock(&fs_info->unused_bgs_lock); + if (!list_empty(&fs_info->reclaim_bgs)) + queue_work(system_unbound_wq, &fs_info->reclaim_bgs_work); + spin_unlock(&fs_info->unused_bgs_lock); +} + +void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg) +{ + struct btrfs_fs_info *fs_info = bg->fs_info; + + spin_lock(&fs_info->unused_bgs_lock); + if (list_empty(&bg->bg_list)) { + btrfs_get_block_group(bg); + trace_btrfs_add_reclaim_block_group(bg); + list_add_tail(&bg->bg_list, &fs_info->reclaim_bgs); + } + spin_unlock(&fs_info->unused_bgs_lock); +} + static int read_bg_from_eb(struct btrfs_fs_info *fs_info, struct btrfs_key *key, struct btrfs_path *path) { @@ -3446,6 +3532,16 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info) } spin_unlock(&info->unused_bgs_lock); + spin_lock(&info->unused_bgs_lock); + while (!list_empty(&info->reclaim_bgs)) { + block_group = list_first_entry(&info->reclaim_bgs, + struct btrfs_block_group, + bg_list); + list_del_init(&block_group->bg_list); + btrfs_put_block_group(block_group); + } + spin_unlock(&info->unused_bgs_lock); + spin_lock(&info->block_group_cache_lock); while ((n = rb_last(&info->block_group_cache_tree)) != NULL) { block_group = rb_entry(n, struct btrfs_block_group, diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h index 3ecc3372a5ce..7b927425dc71 100644 --- a/fs/btrfs/block-group.h +++ b/fs/btrfs/block-group.h @@ -264,6 +264,9 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans, u64 group_start, struct extent_map *em); void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info); void btrfs_mark_bg_unused(struct btrfs_block_group *bg); +void btrfs_reclaim_bgs_work(struct work_struct *work); +void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info); +void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg); int btrfs_read_block_groups(struct btrfs_fs_info *info); int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used, u64 type, u64 chunk_offset, u64 size); diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index c80302564e6b..88531c1fbcdf 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -954,10 +954,14 @@ struct btrfs_fs_info { struct work_struct async_data_reclaim_work; struct work_struct preempt_reclaim_work; + /* Used to reclaim data space in the background */ + struct work_struct reclaim_bgs_work; + spinlock_t unused_bgs_lock; struct list_head unused_bgs; struct mutex unused_bg_unpin_mutex; struct mutex reclaim_bgs_lock; + struct list_head reclaim_bgs; /* Cached block sizes */ u32 nodesize; @@ -998,6 +1002,8 @@ struct btrfs_fs_info { spinlock_t treelog_bg_lock; u64 treelog_bg; + int bg_reclaim_threshold; + #ifdef CONFIG_BTRFS_FS_REF_VERIFY spinlock_t ref_verify_lock; struct rb_root block_tree; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index e52b89ad0a61..942d894ec175 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1898,6 +1898,13 @@ static int cleaner_kthread(void *arg) * unused block groups. */ btrfs_delete_unused_bgs(fs_info); + + /* + * Reclaim block groups in the reclaim_bgs list after we deleted + * all unused block_groups. This possibly gives us some more free + * space. + */ + btrfs_reclaim_bgs(fs_info); sleep: clear_and_wake_up_bit(BTRFS_FS_CLEANER_RUNNING, &fs_info->flags); if (kthread_should_park()) @@ -2886,6 +2893,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) INIT_LIST_HEAD(&fs_info->space_info); INIT_LIST_HEAD(&fs_info->tree_mod_seq_list); INIT_LIST_HEAD(&fs_info->unused_bgs); + INIT_LIST_HEAD(&fs_info->reclaim_bgs); #ifdef CONFIG_BTRFS_DEBUG INIT_LIST_HEAD(&fs_info->allocated_roots); INIT_LIST_HEAD(&fs_info->allocated_ebs); @@ -2974,6 +2982,9 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) fs_info->swapfile_pins = RB_ROOT; fs_info->send_in_progress = 0; + + fs_info->bg_reclaim_threshold = 75; + INIT_WORK(&fs_info->reclaim_bgs_work, btrfs_reclaim_bgs_work); } static int init_mount_fs_info(struct btrfs_fs_info *fs_info, struct super_block *sb) @@ -4332,6 +4343,8 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info) cancel_work_sync(&fs_info->async_data_reclaim_work); cancel_work_sync(&fs_info->preempt_reclaim_work); + cancel_work_sync(&fs_info->reclaim_bgs_work); + /* Cancel or finish ongoing discard work */ btrfs_discard_cleanup(fs_info); diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 9988decd5717..e54466fc101f 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -11,6 +11,7 @@ #include <linux/ratelimit.h> #include <linux/error-injection.h> #include <linux/sched/mm.h> +#include "misc.h" #include "ctree.h" #include "free-space-cache.h" #include "transaction.h" @@ -2539,6 +2540,7 @@ int __btrfs_add_free_space(struct btrfs_fs_info *fs_info, static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, u64 bytenr, u64 size, bool used) { + struct btrfs_fs_info *fs_info = block_group->fs_info; struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl; u64 offset = bytenr - block_group->start; u64 to_free, to_unusable; @@ -2569,8 +2571,13 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, } /* All the region is now unusable. Mark it as unused and reclaim */ - if (block_group->zone_unusable == block_group->length) + if (block_group->zone_unusable == block_group->length) { btrfs_mark_bg_unused(block_group); + } else if (block_group->zone_unusable >= + div_factor_fine(block_group->length, + fs_info->bg_reclaim_threshold)) { + btrfs_mark_bg_to_reclaim(block_group); + } return 0; } diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index a99d1f415a7f..436ac7b4b334 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -980,6 +980,40 @@ static ssize_t btrfs_read_policy_store(struct kobject *kobj, } BTRFS_ATTR_RW(, read_policy, btrfs_read_policy_show, btrfs_read_policy_store); +static ssize_t btrfs_bg_reclaim_threshold_show(struct kobject *kobj, + struct kobj_attribute *a, + char *buf) +{ + struct btrfs_fs_info *fs_info = to_fs_info(kobj); + ssize_t ret; + + ret = scnprintf(buf, PAGE_SIZE, "%d\n", fs_info->bg_reclaim_threshold); + + return ret; +} + +static ssize_t btrfs_bg_reclaim_threshold_store(struct kobject *kobj, + struct kobj_attribute *a, + const char *buf, size_t len) +{ + struct btrfs_fs_info *fs_info = to_fs_info(kobj); + int thresh; + int ret; + + ret = kstrtoint(buf, 10, &thresh); + if (ret) + return ret; + + if (thresh <= 50 || thresh > 100) + return -EINVAL; + + fs_info->bg_reclaim_threshold = thresh; + + return len; +} +BTRFS_ATTR_RW(, bg_reclaim_threshold, btrfs_bg_reclaim_threshold_show, + btrfs_bg_reclaim_threshold_store); + static const struct attribute *btrfs_attrs[] = { BTRFS_ATTR_PTR(, label), BTRFS_ATTR_PTR(, nodesize), @@ -991,6 +1025,7 @@ static const struct attribute *btrfs_attrs[] = { BTRFS_ATTR_PTR(, exclusive_operation), BTRFS_ATTR_PTR(, generation), BTRFS_ATTR_PTR(, read_policy), + BTRFS_ATTR_PTR(, bg_reclaim_threshold), NULL, }; diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index a2a7f5ab0a3e..527324154e3e 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3098,7 +3098,7 @@ int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset) return ret; } -static int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) +int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset) { struct btrfs_root *root = fs_info->chunk_root; struct btrfs_trans_handle *trans; diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index d4c3e0dd32b8..9c0d84e5ec06 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -484,6 +484,7 @@ void btrfs_describe_block_groups(u64 flags, char *buf, u32 size_buf); int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info); int btrfs_recover_balance(struct btrfs_fs_info *fs_info); int btrfs_pause_balance(struct btrfs_fs_info *fs_info); +int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset); int btrfs_cancel_balance(struct btrfs_fs_info *fs_info); int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info); int btrfs_uuid_scan_kthread(void *data); diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index 0551ea65374f..a41dd8a0c730 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -1903,6 +1903,18 @@ DEFINE_EVENT(btrfs__block_group, btrfs_add_unused_block_group, TP_ARGS(bg_cache) ); +DEFINE_EVENT(btrfs__block_group, btrfs_add_reclaim_block_group, + TP_PROTO(const struct btrfs_block_group *bg_cache), + + TP_ARGS(bg_cache) +); + +DEFINE_EVENT(btrfs__block_group, btrfs_reclaim_block_group, + TP_PROTO(const struct btrfs_block_group *bg_cache), + + TP_ARGS(bg_cache) +); + DEFINE_EVENT(btrfs__block_group, btrfs_skip_unused_block_group, TP_PROTO(const struct btrfs_block_group *bg_cache),
When a file gets deleted on a zoned file system, the space freed is not returned back into the block group's free space, but is migrated to zone_unusable. As this zone_unusable space is behind the current write pointer it is not possible to use it for new allocations. In the current implementation a zone is reset once all of the block group's space is accounted as zone unusable. This behaviour can lead to premature ENOSPC errors on a busy file system. Instead of only reclaiming the zone once it is completely unusable, kick off a reclaim job once the amount of unusable bytes exceeds a user configurable threshold between 51% and 100%. It can be set per mounted filesystem via the sysfs tunable bg_reclaim_threshold which is set to 75% per default. Similar to reclaiming unused block groups, these dirty block groups are added to a to_reclaim list and then on a transaction commit, the reclaim process is triggered but after we deleted unused block groups, which will free space for the relocation process. Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> --- fs/btrfs/block-group.c | 96 ++++++++++++++++++++++++++++++++++++ fs/btrfs/block-group.h | 3 ++ fs/btrfs/ctree.h | 6 +++ fs/btrfs/disk-io.c | 13 +++++ fs/btrfs/free-space-cache.c | 9 +++- fs/btrfs/sysfs.c | 35 +++++++++++++ fs/btrfs/volumes.c | 2 +- fs/btrfs/volumes.h | 1 + include/trace/events/btrfs.h | 12 +++++ 9 files changed, 175 insertions(+), 2 deletions(-)