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btrfs: don't miss async discards after scheduled work override 

If btrfs_discard_schedule_work() is called with override=true, it sets
delay anew regardless how much time is left until the timer should have
fired. If delays are long (that can happen, for example, with low
kbps_limit), they might get constantly overridden without having a
chance to run the discard work.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Pavel Begunkov 2020-11-04 09:45:53 +00:00 committed by David Sterba
parent 6e88f116bd
commit df903e5d29
2 changed files with 16 additions and 0 deletions
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1
fs/btrfs/ctree.h
View File

@ -469,6 +469,7 @@ struct btrfs_discard_ctl {
struct btrfs_block_group *block_group;
struct list_head discard_list[BTRFS_NR_DISCARD_LISTS];
u64 prev_discard;
u64 prev_discard_time;
atomic_t discardable_extents;
atomic64_t discardable_bytes;
u64 max_discard_size;

15
fs/btrfs/discard.c
View File

@ -381,6 +381,15 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl,
delay = max(delay, bg_timeout);
}
if (override && discard_ctl->prev_discard) {
u64 elapsed = now - discard_ctl->prev_discard_time;
if (delay > elapsed)
delay -= elapsed;
else
delay = 0;
}
mod_delayed_work(discard_ctl->discard_workers,
&discard_ctl->work, nsecs_to_jiffies(delay));
}
@ -465,7 +474,12 @@ static void btrfs_discard_workfn(struct work_struct *work)
discard_ctl->discard_extent_bytes += trimmed;
}
/*
* Updated without locks as this is inside the workfn and nothing else
* is reading the values
*/
discard_ctl->prev_discard = trimmed;
discard_ctl->prev_discard_time = ktime_get_ns();
/* Determine next steps for a block_group */
if (block_group->discard_cursor >= btrfs_block_group_end(block_group)) {
@ -685,6 +699,7 @@ void btrfs_discard_init(struct btrfs_fs_info *fs_info)
INIT_LIST_HEAD(&discard_ctl->discard_list[i]);
discard_ctl->prev_discard = 0;
discard_ctl->prev_discard_time = 0;
atomic_set(&discard_ctl->discardable_extents, 0);
atomic64_set(&discard_ctl->discardable_bytes, 0);
discard_ctl->max_discard_size = BTRFS_ASYNC_DISCARD_DEFAULT_MAX_SIZE;