From 01e86008aaa534867a7fb0fcbc116ab085e2b2c6 Mon Sep 17 00:00:00 2001
From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Date: Mon, 19 Apr 2021 16:41:00 +0900
Subject: [PATCH] btrfs: zoned: reset zones of relocated block groups
When relocating a block group the freed up space is not discarded in one
big block, but each extent is discarded on its own with -odisard=sync.
For a zoned filesystem we need to discard the whole block group at once,
so btrfs_discard_extent() will translate the discard into a
REQ_OP_ZONE_RESET operation, which then resets the device's zone.
Failure to reset the zone is not fatal error.
Discussion about the approach and regarding transaction blocking:
https://lore.kernel.org/linux-btrfs/CAL3q7H4SjS_d5rBepfTMhU8Th3bJzdmyYd0g4Z60yUgC_rC_ZA@mail.gmail.com/
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
fs/btrfs/volumes.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 517b40439235c..42377afdeb4de 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3103,6 +3103,7 @@ static 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;
struct btrfs_block_group *block_group;
+ u64 length;
int ret;
/*
@@ -3130,8 +3131,23 @@ static int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset)
if (!block_group)
return -ENOENT;
btrfs_discard_cancel_work(&fs_info->discard_ctl, block_group);
+ length = block_group->length;
btrfs_put_block_group(block_group);
+ /*
+ * On a zoned file system, discard the whole block group, this will
+ * trigger a REQ_OP_ZONE_RESET operation on the device zone. If
+ * resetting the zone fails, don't treat it as a fatal problem from the
+ * filesystem's point of view.
+ */
+ if (btrfs_is_zoned(fs_info)) {
+ ret = btrfs_discard_extent(fs_info, chunk_offset, length, NULL);
+ if (ret)
+ btrfs_info(fs_info,
+ "failed to reset zone %llu after relocation",
+ chunk_offset);
+ }
+
trans = btrfs_start_trans_remove_block_group(root->fs_info,
chunk_offset);
if (IS_ERR(trans)) {
--
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