This is a note to let you know that I've just added the patch titled
btrfs: reinterpret async discard iops_limit=0 as no delay
to the 6.2-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-reinterpret-async-discard-iops_limit-0-as-no-delay.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ef9cddfe57d86aac6b509b550136395669159b30 Mon Sep 17 00:00:00 2001
From: Boris Burkov <boris@xxxxxx>
Date: Wed, 5 Apr 2023 12:43:59 -0700
Subject: btrfs: reinterpret async discard iops_limit=0 as no delay
From: Boris Burkov <boris@xxxxxx>
commit ef9cddfe57d86aac6b509b550136395669159b30 upstream.
Currently, a limit of 0 results in a hard coded metering over 6 hours.
Since the default is a set limit, I suspect no one truly depends on this
rather arbitrary setting. Repurpose it for an arguably more useful
"unlimited" mode, where the delay is 0.
Note that if block groups are too new, or go fully empty, there is still
a delay associated with those conditions. Those delays implement
heuristics for not trimming a region we are relatively likely to fully
overwrite soon.
CC: stable@xxxxxxxxxxxxxxx # 6.2+
Reviewed-by: Neal Gompa <neal@xxxxxxxxx>
Signed-off-by: Boris Burkov <boris@xxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/discard.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
--- a/fs/btrfs/discard.c
+++ b/fs/btrfs/discard.c
@@ -56,8 +56,6 @@
#define BTRFS_DISCARD_DELAY (120ULL * NSEC_PER_SEC)
#define BTRFS_DISCARD_UNUSED_DELAY (10ULL * NSEC_PER_SEC)
-/* Target completion latency of discarding all discardable extents */
-#define BTRFS_DISCARD_TARGET_MSEC (6 * 60 * 60UL * MSEC_PER_SEC)
#define BTRFS_DISCARD_MIN_DELAY_MSEC (1UL)
#define BTRFS_DISCARD_MAX_DELAY_MSEC (1000UL)
#define BTRFS_DISCARD_MAX_IOPS (1000U)
@@ -577,6 +575,7 @@ void btrfs_discard_calc_delay(struct btr
s32 discardable_extents;
s64 discardable_bytes;
u32 iops_limit;
+ unsigned long min_delay = BTRFS_DISCARD_MIN_DELAY_MSEC;
unsigned long delay;
discardable_extents = atomic_read(&discard_ctl->discardable_extents);
@@ -607,13 +606,19 @@ void btrfs_discard_calc_delay(struct btr
}
iops_limit = READ_ONCE(discard_ctl->iops_limit);
- if (iops_limit)
+
+ if (iops_limit) {
delay = MSEC_PER_SEC / iops_limit;
- else
- delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents;
+ } else {
+ /*
+ * Unset iops_limit means go as fast as possible, so allow a
+ * delay of 0.
+ */
+ delay = 0;
+ min_delay = 0;
+ }
- delay = clamp(delay, BTRFS_DISCARD_MIN_DELAY_MSEC,
- BTRFS_DISCARD_MAX_DELAY_MSEC);
+ delay = clamp(delay, min_delay, BTRFS_DISCARD_MAX_DELAY_MSEC);
discard_ctl->delay_ms = delay;
spin_unlock(&discard_ctl->lock);
Patches currently in stable-queue which might be from boris@xxxxxx are
queue-6.2/btrfs-reinterpret-async-discard-iops_limit-0-as-no-delay.patch
queue-6.2/btrfs-set-default-discard-iops_limit-to-1000.patch
