btrfs: zoned: activate metadata block group on flush_space

For metadata space on zoned filesystem, reaching ALLOC_CHUNK{,_FORCE}
means we don't have enough space left in the active_total_bytes. Before
allocating a new chunk, we can try to activate an existing block group
in this case.

Also, allocating a chunk is not enough to grant a ticket for metadata
space on zoned filesystem we need to activate the block group to
increase the active_total_bytes.

btrfs_zoned_activate_one_bg() implements the activation feature. It will
activate a block group by (maybe) finishing a block group. It will give up
activating a block group if it cannot finish any block group.

CC: stable@vger.kernel.org # 5.16+
Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking")
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 5284312aad04..d0cbeb7ae81c 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -9,6 +9,7 @@
 #include "ordered-data.h"
 #include "transaction.h"
 #include "block-group.h"
+#include "zoned.h"
 
 /*
  * HOW DOES SPACE RESERVATION WORK
@@ -724,6 +725,18 @@ static void flush_space(struct btrfs_fs_info *fs_info,
 		break;
 	case ALLOC_CHUNK:
 	case ALLOC_CHUNK_FORCE:
+		/*
+		 * For metadata space on zoned filesystem, reaching here means we
+		 * don't have enough space left in active_total_bytes. Try to
+		 * activate a block group first, because we may have inactive
+		 * block group already allocated.
+		 */
+		ret = btrfs_zoned_activate_one_bg(fs_info, space_info, false);
+		if (ret < 0)
+			break;
+		else if (ret == 1)
+			break;
+
 		trans = btrfs_join_transaction(root);
 		if (IS_ERR(trans)) {
 			ret = PTR_ERR(trans);
@@ -734,6 +747,23 @@ static void flush_space(struct btrfs_fs_info *fs_info,
 				(state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
 					CHUNK_ALLOC_FORCE);
 		btrfs_end_transaction(trans);
+
+		/*
+		 * For metadata space on zoned filesystem, allocating a new chunk
+		 * is not enough. We still need to activate the block * group.
+		 * Active the newly allocated block group by (maybe) finishing
+		 * a block group.
+		 */
+		if (ret == 1) {
+			ret = btrfs_zoned_activate_one_bg(fs_info, space_info, true);
+			/*
+			 * Revert to the original ret regardless we could finish
+			 * one block group or not.
+			 */
+			if (ret >= 0)
+				ret = 1;
+		}
+
 		if (ret > 0 || ret == -ENOSPC)
 			ret = 0;
 		break;