This is a note to let you know that I've just added the patch titled
btrfs: zoned: do not enable async discard
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-zoned-do-not-enable-async-discard.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 95ca6599a589ee84c69f02d0e1d928c8d1367fb1 Mon Sep 17 00:00:00 2001
From: Naohiro Aota <naohiro.aota@xxxxxxx>
Date: Thu, 29 Jun 2023 17:37:31 +0900
Subject: btrfs: zoned: do not enable async discard
From: Naohiro Aota <naohiro.aota@xxxxxxx>
commit 95ca6599a589ee84c69f02d0e1d928c8d1367fb1 upstream.
The zoned mode need to reset a zone before using it. We rely on btrfs's
original discard functionality (discarding unused block group range) to do
the resetting.
While the commit 63a7cb130718 ("btrfs: auto enable discard=async when
possible") made the discard done in an async manner, a zoned reset do not
need to be async, as it is fast enough.
Even worth, delaying zone rests prevents using those zones again. So, let's
disable async discard on the zoned mode.
Fixes: 63a7cb130718 ("btrfs: auto enable discard=async when possible")
CC: stable@xxxxxxxxxxxxxxx # 6.3+
Reviewed-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
[ update message text ]
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/disk-io.c | 7 ++++++-
fs/btrfs/zoned.c | 3 +++
2 files changed, 9 insertions(+), 1 deletion(-)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3692,11 +3692,16 @@ int __cold open_ctree(struct super_block
* For devices supporting discard turn on discard=async automatically,
* unless it's already set or disabled. This could be turned off by
* nodiscard for the same mount.
+ *
+ * The zoned mode piggy backs on the discard functionality for
+ * resetting a zone. There is no reason to delay the zone reset as it is
+ * fast enough. So, do not enable async discard for zoned mode.
*/
if (!(btrfs_test_opt(fs_info, DISCARD_SYNC) ||
btrfs_test_opt(fs_info, DISCARD_ASYNC) ||
btrfs_test_opt(fs_info, NODISCARD)) &&
- fs_info->fs_devices->discardable) {
+ fs_info->fs_devices->discardable &&
+ !btrfs_is_zoned(fs_info)) {
btrfs_set_and_info(fs_info, DISCARD_ASYNC,
"auto enabling async discard");
}
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -804,6 +804,9 @@ int btrfs_check_mountopts_zoned(struct b
return -EINVAL;
}
+ btrfs_clear_and_info(info, DISCARD_ASYNC,
+ "zoned: async discard ignored and disabled for zoned mode");
+
return 0;
}
Patches currently in stable-queue which might be from naohiro.aota@xxxxxxx are
queue-6.4/btrfs-zoned-do-not-enable-async-discard.patch
