diff mbox series

[1/2] btrfs: zoned: reserve relocation zone on mount

Message ID 20240514-zoned-gc-v1-1-109f1a6c7447@kernel.org (mailing list archive)
State New, archived
Headers show
Series btrfs: zoned: always set aside a zone for relocation | expand

Commit Message

Johannes Thumshirn May 14, 2024, 9:13 p.m. UTC
From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Reserve one zone as a data relocation target on each mount. If we already
find one empty block group, there's no need to force a chunk allocation,
but we can use this empty data block group as our relocation target.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/disk-io.c |  2 ++
 fs/btrfs/zoned.c   | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/zoned.h   |  3 +++
 3 files changed, 65 insertions(+)

Comments

Naohiro Aota May 15, 2024, 5:58 p.m. UTC | #1
On Tue, May 14, 2024 at 11:13:21PM +0200, Johannes Thumshirn wrote:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> 
> Reserve one zone as a data relocation target on each mount. If we already
> find one empty block group, there's no need to force a chunk allocation,
> but we can use this empty data block group as our relocation target.
> 
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  fs/btrfs/disk-io.c |  2 ++
>  fs/btrfs/zoned.c   | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/btrfs/zoned.h   |  3 +++
>  3 files changed, 65 insertions(+)
> 
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index a91a8056758a..0490f2f45fb1 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3558,6 +3558,8 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
>  	}
>  	btrfs_discard_resume(fs_info);
>  
> +	btrfs_reserve_relocation_zone(fs_info);
> +
>  	if (fs_info->uuid_root &&
>  	    (btrfs_test_opt(fs_info, RESCAN_UUID_TREE) ||
>  	     fs_info->generation != btrfs_super_uuid_tree_generation(disk_super))) {
> diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
> index 4cba80b34387..b752f8c95f40 100644
> --- a/fs/btrfs/zoned.c
> +++ b/fs/btrfs/zoned.c
> @@ -17,6 +17,7 @@
>  #include "fs.h"
>  #include "accessors.h"
>  #include "bio.h"
> +#include "transaction.h"
>  
>  /* Maximum number of zones to report per blkdev_report_zones() call */
>  #define BTRFS_REPORT_NR_ZONES   4096
> @@ -2634,3 +2635,62 @@ void btrfs_check_active_zone_reservation(struct btrfs_fs_info *fs_info)
>  	}
>  	spin_unlock(&fs_info->zone_active_bgs_lock);
>  }
> +
> +static u64 find_empty_block_group(struct btrfs_space_info *sinfo, u64 flags)
> +{
> +	struct btrfs_block_group *bg;
> +
> +	for (int i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
> +		list_for_each_entry(bg, &sinfo->block_groups[i], list) {
> +			if (bg->flags != flags)
> +				continue;
> +			if (bg->used == 0)
> +				return bg->start;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +void btrfs_reserve_relocation_zone(struct btrfs_fs_info *fs_info)

This function reserves the data relocation block group but not a zone. So,
I'd prefer "btrfs_reserve_relocation_block_group" or "..._bg".

> +{
> +	struct btrfs_root *tree_root = fs_info->tree_root;
> +	struct btrfs_space_info *sinfo = fs_info->data_sinfo;
> +	struct btrfs_trans_handle *trans;
> +	u64 flags = btrfs_get_alloc_profile(fs_info, sinfo->flags);
> +	u64 bytenr = 0;
> +
> +	lockdep_assert_not_held(&fs_info->relocation_bg_lock);
> +
> +	if (!btrfs_is_zoned(fs_info))
> +		return;
> +

Don't we need to check fs_info->data_reloc_bg first? If we don't find an
empty BG and we fail to allocate a new BG, this is going to kill the
existing data reloc BG. It's OK for mount time. But, this is going to be
called on runtime in the next patch.

> +	bytenr = find_empty_block_group(sinfo, flags);
> +	if (!bytenr) {
> +		int ret;
> +
> +		trans = btrfs_join_transaction(tree_root);
> +		if (IS_ERR(trans))
> +			return;
> +
> +		ret = btrfs_chunk_alloc(trans, flags, CHUNK_ALLOC_FORCE);
> +		btrfs_end_transaction(trans);

I'd like to have a comment on the error case, especially relates to the
above point. Is it OK to override fs_info->data_reloc_bg to 0 in the error
case?

> +
> +		if (!ret) {
> +			struct btrfs_block_group *bg;
> +
> +			bytenr = find_empty_block_group(sinfo, flags);
> +			if (!bytenr)

Maybe, same here. This is a case of someone stealing the allocated
chunk. Isn't it worth retrying? Especially when this function is called on
runtime?

> +				goto out;
> +			bg = btrfs_lookup_block_group(fs_info, bytenr);
> +			ASSERT(bg);
> +
> +			if (!btrfs_zone_activate(bg))
> +				bytenr = 0;
> +			btrfs_put_block_group(bg);
> +		}
> +	}
> +
> +out:
> +	fs_info->data_reloc_bg = bytenr;
> +}
> diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
> index 77c4321e331f..048ffada4549 100644
> --- a/fs/btrfs/zoned.h
> +++ b/fs/btrfs/zoned.h
> @@ -97,6 +97,7 @@ int btrfs_zone_finish_one_bg(struct btrfs_fs_info *fs_info);
>  int btrfs_zoned_activate_one_bg(struct btrfs_fs_info *fs_info,
>  				struct btrfs_space_info *space_info, bool do_finish);
>  void btrfs_check_active_zone_reservation(struct btrfs_fs_info *fs_info);
> +void btrfs_reserve_relocation_zone(struct btrfs_fs_info *fs_info);
>  #else /* CONFIG_BLK_DEV_ZONED */
>  static inline int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
>  				     struct blk_zone *zone)
> @@ -271,6 +272,8 @@ static inline int btrfs_zoned_activate_one_bg(struct btrfs_fs_info *fs_info,
>  
>  static inline void btrfs_check_active_zone_reservation(struct btrfs_fs_info *fs_info) { }
>  
> +static inline void btrfs_reserve_relocation_zone(struct btrfs_fs_info *fs_info) { }
> +
>  #endif
>  
>  static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)
> 
> -- 
> 2.35.3
>
diff mbox series

Patch

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a91a8056758a..0490f2f45fb1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3558,6 +3558,8 @@  int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	}
 	btrfs_discard_resume(fs_info);
 
+	btrfs_reserve_relocation_zone(fs_info);
+
 	if (fs_info->uuid_root &&
 	    (btrfs_test_opt(fs_info, RESCAN_UUID_TREE) ||
 	     fs_info->generation != btrfs_super_uuid_tree_generation(disk_super))) {
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 4cba80b34387..b752f8c95f40 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -17,6 +17,7 @@ 
 #include "fs.h"
 #include "accessors.h"
 #include "bio.h"
+#include "transaction.h"
 
 /* Maximum number of zones to report per blkdev_report_zones() call */
 #define BTRFS_REPORT_NR_ZONES   4096
@@ -2634,3 +2635,62 @@  void btrfs_check_active_zone_reservation(struct btrfs_fs_info *fs_info)
 	}
 	spin_unlock(&fs_info->zone_active_bgs_lock);
 }
+
+static u64 find_empty_block_group(struct btrfs_space_info *sinfo, u64 flags)
+{
+	struct btrfs_block_group *bg;
+
+	for (int i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
+		list_for_each_entry(bg, &sinfo->block_groups[i], list) {
+			if (bg->flags != flags)
+				continue;
+			if (bg->used == 0)
+				return bg->start;
+		}
+	}
+
+	return 0;
+}
+
+void btrfs_reserve_relocation_zone(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_root *tree_root = fs_info->tree_root;
+	struct btrfs_space_info *sinfo = fs_info->data_sinfo;
+	struct btrfs_trans_handle *trans;
+	u64 flags = btrfs_get_alloc_profile(fs_info, sinfo->flags);
+	u64 bytenr = 0;
+
+	lockdep_assert_not_held(&fs_info->relocation_bg_lock);
+
+	if (!btrfs_is_zoned(fs_info))
+		return;
+
+	bytenr = find_empty_block_group(sinfo, flags);
+	if (!bytenr) {
+		int ret;
+
+		trans = btrfs_join_transaction(tree_root);
+		if (IS_ERR(trans))
+			return;
+
+		ret = btrfs_chunk_alloc(trans, flags, CHUNK_ALLOC_FORCE);
+		btrfs_end_transaction(trans);
+
+		if (!ret) {
+			struct btrfs_block_group *bg;
+
+			bytenr = find_empty_block_group(sinfo, flags);
+			if (!bytenr)
+				goto out;
+			bg = btrfs_lookup_block_group(fs_info, bytenr);
+			ASSERT(bg);
+
+			if (!btrfs_zone_activate(bg))
+				bytenr = 0;
+			btrfs_put_block_group(bg);
+		}
+	}
+
+out:
+	fs_info->data_reloc_bg = bytenr;
+}
diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index 77c4321e331f..048ffada4549 100644
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -97,6 +97,7 @@  int btrfs_zone_finish_one_bg(struct btrfs_fs_info *fs_info);
 int btrfs_zoned_activate_one_bg(struct btrfs_fs_info *fs_info,
 				struct btrfs_space_info *space_info, bool do_finish);
 void btrfs_check_active_zone_reservation(struct btrfs_fs_info *fs_info);
+void btrfs_reserve_relocation_zone(struct btrfs_fs_info *fs_info);
 #else /* CONFIG_BLK_DEV_ZONED */
 static inline int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 				     struct blk_zone *zone)
@@ -271,6 +272,8 @@  static inline int btrfs_zoned_activate_one_bg(struct btrfs_fs_info *fs_info,
 
 static inline void btrfs_check_active_zone_reservation(struct btrfs_fs_info *fs_info) { }
 
+static inline void btrfs_reserve_relocation_zone(struct btrfs_fs_info *fs_info) { }
+
 #endif
 
 static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)