From dfb79ddb130e0a239e3e90aaf5f5b908555f52bb Mon Sep 17 00:00:00 2001 From: Dennis Zhou Date: Fri, 13 Dec 2019 16:22:20 -0800 Subject: btrfs: track discardable extents for async discard The number of discardable extents will serve as the rate limiting metric for how often we should discard. This keeps track of discardable extents in the free space caches by maintaining deltas and propagating them to the global count. The deltas are calculated from 2 values stored in PREV and CURR entries, then propagated up to the global discard ctl. The current counter value becomes the previous counter value after update. Signed-off-by: Dennis Zhou Reviewed-by: David Sterba [ update changelog ] Signed-off-by: David Sterba --- fs/btrfs/sysfs.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'fs/btrfs/sysfs.c') diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 0eec1a8d45bd..0ac122c67065 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -12,6 +12,7 @@ #include #include "ctree.h" +#include "discard.h" #include "disk-io.h" #include "transaction.h" #include "sysfs.h" @@ -341,7 +342,21 @@ static const struct attribute_group btrfs_static_feature_attr_group = { /* * Discard statistics and tunables */ +#define discard_to_fs_info(_kobj) to_fs_info((_kobj)->parent->parent) + +static ssize_t btrfs_discardable_extents_show(struct kobject *kobj, + struct kobj_attribute *a, + char *buf) +{ + struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj); + + return snprintf(buf, PAGE_SIZE, "%d\n", + atomic_read(&fs_info->discard_ctl.discardable_extents)); +} +BTRFS_ATTR(discard, discardable_extents, btrfs_discardable_extents_show); + static const struct attribute *discard_debug_attrs[] = { + BTRFS_ATTR_PTR(discard, discardable_extents), NULL, }; -- cgit v1.2.3