btrfs: keep track of discard reuse stats

Keep track of how much we are discarding and how often we are reusing
with async discard. The discard_*_bytes values don't need any special
protection because the work item provides the single threaded access.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 486b9d1532eb37f8f8e4c23a96c3e922b898786c..569931dd0ce55bd58655c3121c26924b30cf00cf 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -473,6 +473,9 @@ struct btrfs_discard_ctl {
        unsigned long delay;
        u32 iops_limit;
        u32 kbps_limit;
+       u64 discard_extent_bytes;
+       u64 discard_bitmap_bytes;
+       atomic64_t discard_bytes_saved;
 };
 
 /* delayed seq elem */

diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
index 5af42e0317b7d95dbd6f5777f3beab84668ac3bc..40dcb5dcdc9573b088ed22391aaa97c2f837c072 100644 (file)
--- a/fs/btrfs/discard.c
+++ b/fs/btrfs/discard.c
@@ -417,11 +417,13 @@ static void btrfs_discard_workfn(struct work_struct *work)
                                       block_group->discard_cursor,
                                       btrfs_block_group_end(block_group),
                                       minlen, maxlen, true);
+               discard_ctl->discard_bitmap_bytes += trimmed;
        } else {
                btrfs_trim_block_group_extents(block_group, &trimmed,
                                       block_group->discard_cursor,
                                       btrfs_block_group_end(block_group),
                                       minlen, true);
+               discard_ctl->discard_extent_bytes += trimmed;
        }
 
        discard_ctl->prev_discard = trimmed;
@@ -626,6 +628,9 @@ void btrfs_discard_init(struct btrfs_fs_info *fs_info)
        discard_ctl->delay = BTRFS_DISCARD_MAX_DELAY_MSEC;
        discard_ctl->iops_limit = BTRFS_DISCARD_MAX_IOPS;
        discard_ctl->kbps_limit = 0;
+       discard_ctl->discard_extent_bytes = 0;
+       discard_ctl->discard_bitmap_bytes = 0;
+       atomic64_set(&discard_ctl->discard_bytes_saved, 0);
 }
 
 void btrfs_discard_cleanup(struct btrfs_fs_info *fs_info)

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index a4340657b7f1566b1fad6d6eb8838fff5ddb7bc6..802e06d6303dcc692e95464e5498dbd165258d9a 100644 (file)
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2842,6 +2842,8 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group *block_group,
                               u64 *max_extent_size)
 {
        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+       struct btrfs_discard_ctl *discard_ctl =
+                                       &block_group->fs_info->discard_ctl;
        struct btrfs_free_space *entry = NULL;
        u64 bytes_search = bytes + empty_size;
        u64 ret = 0;
@@ -2858,6 +2860,10 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group *block_group,
        ret = offset;
        if (entry->bitmap) {
                bitmap_clear_bits(ctl, entry, offset, bytes);
+
+               if (!btrfs_free_space_trimmed(entry))
+                       atomic64_add(bytes, &discard_ctl->discard_bytes_saved);
+
                if (!entry->bytes)
                        free_bitmap(ctl, entry);
        } else {
@@ -2866,6 +2872,9 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group *block_group,
                align_gap = entry->offset;
                align_gap_trim_state = entry->trim_state;
 
+               if (!btrfs_free_space_trimmed(entry))
+                       atomic64_add(bytes, &discard_ctl->discard_bytes_saved);
+
                entry->offset = offset + bytes;
                WARN_ON(entry->bytes < bytes + align_gap_len);
 
@@ -2969,6 +2978,8 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group,
                             u64 min_start, u64 *max_extent_size)
 {
        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+       struct btrfs_discard_ctl *discard_ctl =
+                                       &block_group->fs_info->discard_ctl;
        struct btrfs_free_space *entry = NULL;
        struct rb_node *node;
        u64 ret = 0;
@@ -3033,6 +3044,9 @@ out:
 
        spin_lock(&ctl->tree_lock);
 
+       if (!btrfs_free_space_trimmed(entry))
+               atomic64_add(bytes, &discard_ctl->discard_bytes_saved);
+
        ctl->free_space -= bytes;
        if (!entry->bitmap && !btrfs_free_space_trimmed(entry))
                ctl->discardable_bytes[BTRFS_STAT_CURR] -= bytes;

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index eac0155bf8c7765a2a66848e7674d86cca0cefb6..55e4ed1af29cf9b5a5ae72732cf910d6530a926f 100644 (file)
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -366,6 +366,39 @@ static ssize_t btrfs_discardable_extents_show(struct kobject *kobj,
 }
 BTRFS_ATTR(discard, discardable_extents, btrfs_discardable_extents_show);
 
+static ssize_t btrfs_discard_bitmap_bytes_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, "%lld\n",
+                       fs_info->discard_ctl.discard_bitmap_bytes);
+}
+BTRFS_ATTR(discard, discard_bitmap_bytes, btrfs_discard_bitmap_bytes_show);
+
+static ssize_t btrfs_discard_bytes_saved_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, "%lld\n",
+               atomic64_read(&fs_info->discard_ctl.discard_bytes_saved));
+}
+BTRFS_ATTR(discard, discard_bytes_saved, btrfs_discard_bytes_saved_show);
+
+static ssize_t btrfs_discard_extent_bytes_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, "%lld\n",
+                       fs_info->discard_ctl.discard_extent_bytes);
+}
+BTRFS_ATTR(discard, discard_extent_bytes, btrfs_discard_extent_bytes_show);
+
 static ssize_t btrfs_discard_iops_limit_show(struct kobject *kobj,
                                             struct kobj_attribute *a,
                                             char *buf)
@@ -459,6 +492,9 @@ BTRFS_ATTR_RW(discard, max_discard_size, btrfs_discard_max_discard_size_show,
 static const struct attribute *discard_debug_attrs[] = {
        BTRFS_ATTR_PTR(discard, discardable_bytes),
        BTRFS_ATTR_PTR(discard, discardable_extents),
+       BTRFS_ATTR_PTR(discard, discard_bitmap_bytes),
+       BTRFS_ATTR_PTR(discard, discard_bytes_saved),
+       BTRFS_ATTR_PTR(discard, discard_extent_bytes),
        BTRFS_ATTR_PTR(discard, iops_limit),
        BTRFS_ATTR_PTR(discard, kbps_limit),
        BTRFS_ATTR_PTR(discard, max_discard_size),