[PATCH v2] btrfs: zoned: make auto-reclaim less aggressive

[PATCH v2] btrfs: zoned: make auto-reclaim less aggressive

[Johannes Thumshirn]

The current auto-reclaim algorithm starts reclaiming all block-group's
with a zone_unusable value above a configured threshold. This is causing a
lot of reclaim IO even if there would be enough free zones on the device.

Instead of only accounting a block-group's zone_unusable value, also take
the number of empty zones into account.

Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

---
Changes since RFC:
* Fix logic error
* Skip unavailable devices
* Use different metric working for non-zoned devices as well
---
 fs/btrfs/block-group.c |  3 +++
 fs/btrfs/zoned.c       | 30 ++++++++++++++++++++++++++++++
 fs/btrfs/zoned.h       |  6 ++++++
 3 files changed, 39 insertions(+)

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index c22d287e020b..2e77b38c538b 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1522,6 +1522,9 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
 	if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))
 		return;
 
+	if (!btrfs_zoned_should_reclaim(fs_info))
+		return;
+
 	sb_start_write(fs_info->sb);
 
 	if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) {
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 49446bb5a5d1..e60fa3c9be7c 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -15,6 +15,7 @@
 #include "transaction.h"
 #include "dev-replace.h"
 #include "space-info.h"
+#include "misc.h"
 
 /* Maximum number of zones to report per blkdev_report_zones() call */
 #define BTRFS_REPORT_NR_ZONES   4096
@@ -2078,3 +2079,32 @@ void btrfs_free_zone_cache(struct btrfs_fs_info *fs_info)
 	}
 	mutex_unlock(&fs_devices->device_list_mutex);
 }
+
+bool btrfs_zoned_should_reclaim(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+	struct btrfs_device *device;
+	u64 bytes_used = 0;
+	u64 total_bytes = 0;
+	u64 factor;
+
+	if (!btrfs_is_zoned(fs_info))
+		return false;
+
+	if (!fs_info->bg_reclaim_threshold)
+		return false;
+
+	mutex_lock(&fs_devices->device_list_mutex);
+	list_for_each_entry(device, &fs_devices->devices, dev_list) {
+		if (!device->bdev)
+			continue;
+
+		total_bytes += device->disk_total_bytes;
+		bytes_used += device->bytes_used;
+
+	}
+	mutex_unlock(&fs_devices->device_list_mutex);
+
+	factor = (bytes_used * 100) / total_bytes;
+	return factor >= fs_info->bg_reclaim_threshold;
+}
diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index cbf016a7bb5d..d0d0e5c02606 100644
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h
@@ -78,6 +78,7 @@ void btrfs_zone_finish_endio(struct btrfs_fs_info *fs_info, u64 logical,
 			     u64 length);
 void btrfs_clear_data_reloc_bg(struct btrfs_block_group *bg);
 void btrfs_free_zone_cache(struct btrfs_fs_info *fs_info);
+bool btrfs_zoned_should_reclaim(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)
@@ -236,6 +237,11 @@ static inline void btrfs_zone_finish_endio(struct btrfs_fs_info *fs_info,
 static inline void btrfs_clear_data_reloc_bg(struct btrfs_block_group *bg) { }
 
 static inline void btrfs_free_zone_cache(struct btrfs_fs_info *fs_info) { }
+
+static inline bool btrfs_zoned_should_reclaim(struct btrfs_fs_info *fs_info)
+{
+	return false;
+}
 #endif
 
 static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)
-- 
2.35.1

Re: [PATCH v2] btrfs: zoned: make auto-reclaim less aggressive

[kernel test robot]

Hi Johannes,

I love your patch! Yet something to improve:

[auto build test ERROR on kdave/for-next]
[also build test ERROR on next-20220310]
[cannot apply to v5.17-rc8]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Johannes-Thumshirn/btrfs-zoned-make-auto-reclaim-less-aggressive/20220314-231037
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: hexagon-randconfig-r041-20220313 (https://download.01.org/0day-ci/archive/20220315/202203150504.VbCtEy3b-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 3e4950d7fa78ac83f33bbf1658e2f49a73719236)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/e742bf2051b5066cae517342b8bbe81eb44809a4
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Johannes-Thumshirn/btrfs-zoned-make-auto-reclaim-less-aggressive/20220314-231037
        git checkout e742bf2051b5066cae517342b8bbe81eb44809a4
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: __hexagon_udivdi3
   >>> referenced by zoned.c
   >>>               btrfs/zoned.o:(btrfs_zoned_should_reclaim) in archive fs/built-in.a
   >>> referenced by zoned.c
   >>>               btrfs/zoned.o:(btrfs_zoned_should_reclaim) in archive fs/built-in.a
   >>> did you mean: __hexagon_udivsi3
   >>> defined in: arch/hexagon/built-in.a(lib/udivsi3.o)

---
0-DAY CI Kernel Test Service
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org