FAILED: patch "[PATCH] btrfs: zoned: enable metadata over-commit for non-ZNS setup" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Possible dependencies:

85e79ec7b78f ("btrfs: zoned: enable metadata over-commit for non-ZNS setup") c52cc7b7acfb ("btrfs: add a BTRFS_FS_NEED_TRANS_COMMIT flag") 7966a6b5959b ("btrfs: move fs_info::flags enum to fs.h") fc97a410bd78 ("btrfs: move mount option definitions to fs.h") 0d3a9cf8c306 ("btrfs: convert incompat and compat flag test helpers to macros") ec8eb376e271 ("btrfs: move BTRFS_FS_STATE* definitions and helpers to fs.h") 9b569ea0be6f ("btrfs: move the printk helpers out of ctree.h") e118578a8df7 ("btrfs: move assert helpers out of ctree.h") c7f13d428ea1 ("btrfs: move fs wide helpers out of ctree.h") 63a7cb130718 ("btrfs: auto enable discard=async when possible") f1e5c6185ca1 ("btrfs: move flush related definitions to space-info.h") 4300c58f8090 ("btrfs: move btrfs on-disk definitions out of ctree.h") d60d956eb41f ("btrfs: remove unused set/clear_pending_info helpers")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 85e79ec7b78f863178ca488fd8cb5b3de6347756 Mon Sep 17 00:00:00 2001
From: Naohiro Aota <[email protected]>
Date: Tue, 10 Jan 2023 15:04:32 +0900
Subject: [PATCH] btrfs: zoned: enable metadata over-commit for non-ZNS setup

The commit 79417d040f4f ("btrfs: zoned: disable metadata overcommit for zoned") disabled the metadata over-commit to track active zones properly.

However, it also introduced a heavy overhead by allocating new metadata block groups and/or flushing dirty buffers to release the space reservations. Specifically, a workload (write only without any sync operations) worsen its performance from 343.77 MB/sec (v5.19) to 182.89 MB/sec (v6.0).

The performance is still bad on current misc-next which is 187.95 MB/sec. And, with this patch applied, it improves back to 326.70 MB/sec (+73.82%).

This patch introduces a new fs_info->flag BTRFS_FS_NO_OVERCOMMIT to indicate it needs to disable the metadata over-commit. The flag is enabled when a device with max active zones limit is loaded into a file-system.

index a749367e5ae2..37b86acfcbcf 100644
@@ -119,6 +119,12 @@ enum {
 	/* Indicate that we want to commit the transaction. */
 	BTRFS_FS_NEED_TRANS_COMMIT,
 
+	/*
+	 * Indicate metadata over-commit is disabled. This is set when active
+	 * zone tracking is needed.
+	 */
+	BTRFS_FS_NO_OVERCOMMIT,
+
 #if BITS_PER_LONG == 32
 	/* Indicate if we have error/warn message printed on 32bit systems */
 	BTRFS_FS_32BIT_ERROR,

index d28ee4e36f3d..69c09508afb5 100644
@@ -407,7 +407,8 @@ int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
 		return 0;
 
 	used = btrfs_space_info_used(space_info, true);
-	if (btrfs_is_zoned(fs_info) && (space_info->flags & BTRFS_BLOCK_GROUP_METADATA))
+	if (test_bit(BTRFS_FS_NO_OVERCOMMIT, &fs_info->flags) &&
+	    (space_info->flags & BTRFS_BLOCK_GROUP_METADATA))
 		avail = 0;
 	else
 		avail = calc_available_free_space(fs_info, space_info, flush);

index a759668477bb..1f503e8e42d4 100644
@@ -539,6 +539,8 @@ int btrfs_get_dev_zone_info(struct btrfs_device *device, bool populate_cache)
 		}
 		atomic_set(&zone_info->active_zones_left,
 			   max_active_zones - nactive);
+		/* Overcommit does not work well with active zone tacking. */
+		set_bit(BTRFS_FS_NO_OVERCOMMIT, &fs_info->flags);
 	}
 
 	/* Validate superblock log */