diff mbox series

[04/12] btrfs: make max async discard size tunable

Message ID 786ac88afbfaa7993449811b282ea8790ba02338.1577999991.git.dennis@kernel.org
State New, archived
Headers show
Series btrfs: async discard follow up | expand

Commit Message

Dennis Zhou Jan. 2, 2020, 9:26 p.m. UTC
Expose max_discard_size as a tunable via sysfs.

Signed-off-by: Dennis Zhou <dennis@kernel.org>
---
 fs/btrfs/ctree.h            |  1 +
 fs/btrfs/discard.c          |  1 +
 fs/btrfs/discard.h          |  2 +-
 fs/btrfs/free-space-cache.c | 19 ++++++++++++-------
 fs/btrfs/sysfs.c            | 31 +++++++++++++++++++++++++++++++
 5 files changed, 46 insertions(+), 8 deletions(-)

Comments

David Sterba Jan. 3, 2020, 2:44 p.m. UTC | #1
On Thu, Jan 02, 2020 at 04:26:38PM -0500, Dennis Zhou wrote:
> -#define BTRFS_ASYNC_DISCARD_MAX_SIZE	(SZ_64M)
> +#define BTRFS_ASYNC_DISCARD_DFL_MAX_SIZE	(SZ_64M)

I'd prefer to spell DEFAULT, so changed it to that. The identifier
would be long in both cases so let's pick the descriptive version.
diff mbox series

Patch

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2485cf94b628..9328a0398678 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -469,6 +469,7 @@  struct btrfs_discard_ctl {
 	u64 prev_discard;
 	atomic_t discardable_extents;
 	atomic64_t discardable_bytes;
+	u64 max_discard_size;
 	unsigned long delay;
 	unsigned iops_limit;
 	u32 kbps_limit;
diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c
index eb148ca9a508..822b888d90e3 100644
--- a/fs/btrfs/discard.c
+++ b/fs/btrfs/discard.c
@@ -527,6 +527,7 @@  void btrfs_discard_init(struct btrfs_fs_info *fs_info)
 	discard_ctl->prev_discard = 0;
 	atomic_set(&discard_ctl->discardable_extents, 0);
 	atomic64_set(&discard_ctl->discardable_bytes, 0);
+	discard_ctl->max_discard_size = BTRFS_ASYNC_DISCARD_DFL_MAX_SIZE;
 	discard_ctl->delay = BTRFS_DISCARD_MAX_DELAY_MSEC;
 	discard_ctl->iops_limit = BTRFS_DISCARD_MAX_IOPS;
 	discard_ctl->kbps_limit = 0;
diff --git a/fs/btrfs/discard.h b/fs/btrfs/discard.h
index 562c60fab77a..72816e479416 100644
--- a/fs/btrfs/discard.h
+++ b/fs/btrfs/discard.h
@@ -10,7 +10,7 @@  struct btrfs_discard_ctl;
 struct btrfs_block_group;
 
 /* Discard size limits */
-#define BTRFS_ASYNC_DISCARD_MAX_SIZE	(SZ_64M)
+#define BTRFS_ASYNC_DISCARD_DFL_MAX_SIZE	(SZ_64M)
 
 /* Work operations */
 void btrfs_discard_cancel_work(struct btrfs_discard_ctl *discard_ctl,
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 34291c777998..fb1a53f9b39c 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3428,6 +3428,8 @@  static int trim_no_bitmap(struct btrfs_block_group *block_group,
 			  u64 *total_trimmed, u64 start, u64 end, u64 minlen,
 			  bool async)
 {
+	struct btrfs_discard_ctl *discard_ctl =
+					&block_group->fs_info->discard_ctl;
 	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 	struct btrfs_free_space *entry;
 	struct rb_node *node;
@@ -3436,6 +3438,7 @@  static int trim_no_bitmap(struct btrfs_block_group *block_group,
 	u64 extent_bytes;
 	enum btrfs_trim_state extent_trim_state;
 	u64 bytes;
+	u64 max_discard_size = READ_ONCE(discard_ctl->max_discard_size);
 
 	while (start < end) {
 		struct btrfs_trim_range trim_entry;
@@ -3475,11 +3478,10 @@  static int trim_no_bitmap(struct btrfs_block_group *block_group,
 				goto next;
 			}
 			unlink_free_space(ctl, entry);
-			if (bytes > BTRFS_ASYNC_DISCARD_MAX_SIZE) {
-				bytes = extent_bytes =
-					BTRFS_ASYNC_DISCARD_MAX_SIZE;
-				entry->offset += BTRFS_ASYNC_DISCARD_MAX_SIZE;
-				entry->bytes -= BTRFS_ASYNC_DISCARD_MAX_SIZE;
+			if (max_discard_size && bytes > max_discard_size) {
+				bytes = extent_bytes = max_discard_size;
+				entry->offset += max_discard_size;
+				entry->bytes -= max_discard_size;
 				link_free_space(ctl, entry);
 			} else {
 				kmem_cache_free(btrfs_free_space_cachep, entry);
@@ -3584,12 +3586,15 @@  static int trim_bitmaps(struct btrfs_block_group *block_group,
 			u64 *total_trimmed, u64 start, u64 end, u64 minlen,
 			bool async)
 {
+	struct btrfs_discard_ctl *discard_ctl =
+					&block_group->fs_info->discard_ctl;
 	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 	struct btrfs_free_space *entry;
 	int ret = 0;
 	int ret2;
 	u64 bytes;
 	u64 offset = offset_to_bitmap(ctl, start);
+	u64 max_discard_size = READ_ONCE(discard_ctl->max_discard_size);
 
 	while (offset < end) {
 		bool next_bitmap = false;
@@ -3659,8 +3664,8 @@  static int trim_bitmaps(struct btrfs_block_group *block_group,
 			goto next;
 		}
 
-		if (async && bytes > BTRFS_ASYNC_DISCARD_MAX_SIZE)
-			bytes = BTRFS_ASYNC_DISCARD_MAX_SIZE;
+		if (async && max_discard_size && bytes > max_discard_size)
+			bytes = max_discard_size;
 
 		bitmap_clear_bits(ctl, entry, start, bytes);
 		if (entry->bytes == 0)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 39b59f368f06..8b0fd8557438 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -404,6 +404,36 @@  static ssize_t btrfs_discard_kbps_limit_store(struct kobject *kobj,
 BTRFS_ATTR_RW(discard, kbps_limit, btrfs_discard_kbps_limit_show,
 	      btrfs_discard_kbps_limit_store);
 
+static ssize_t btrfs_discard_max_discard_size_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, "%llu\n",
+			READ_ONCE(fs_info->discard_ctl.max_discard_size));
+}
+
+static ssize_t btrfs_discard_max_discard_size_store(struct kobject *kobj,
+						    struct kobj_attribute *a,
+						    const char *buf, size_t len)
+{
+	struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
+	struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl;
+	u64 max_discard_size;
+	int ret;
+
+	ret = kstrtou64(buf, 10, &max_discard_size);
+	if (ret)
+		return -EINVAL;
+
+	WRITE_ONCE(discard_ctl->max_discard_size, max_discard_size);
+
+	return len;
+}
+BTRFS_ATTR_RW(discard, max_discard_size, btrfs_discard_max_discard_size_show,
+	      btrfs_discard_max_discard_size_store);
+
 static ssize_t btrfs_discardable_extents_show(struct kobject *kobj,
 					      struct kobj_attribute *a,
 					      char *buf)
@@ -429,6 +459,7 @@  BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show);
 static const struct attribute *discard_debug_attrs[] = {
 	BTRFS_ATTR_PTR(discard, iops_limit),
 	BTRFS_ATTR_PTR(discard, kbps_limit),
+	BTRFS_ATTR_PTR(discard, max_discard_size),
 	BTRFS_ATTR_PTR(discard, discardable_extents),
 	BTRFS_ATTR_PTR(discard, discardable_bytes),
 	NULL,