Btrfs: account for crcs in delayed ref processing
As we delete large extents, we end up doing huge amounts of COW in order
to delete the corresponding crcs. This adds accounting so that we keep
track of that space and flushing of delayed refs so that we don't build
up too much delayed crc work.
This helps limit the delayed work that must be done at commit time and
tries to avoid ENOSPC aborts because the crcs eat all the global
reserves.
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 6d16bea..8f8ed7d 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -489,11 +489,13 @@
* existing and update must have the same bytenr
*/
static noinline void
-update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
+update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
+ struct btrfs_delayed_ref_node *existing,
struct btrfs_delayed_ref_node *update)
{
struct btrfs_delayed_ref_head *existing_ref;
struct btrfs_delayed_ref_head *ref;
+ int old_ref_mod;
existing_ref = btrfs_delayed_node_to_head(existing);
ref = btrfs_delayed_node_to_head(update);
@@ -541,7 +543,20 @@
* only need the lock for this case cause we could be processing it
* currently, for refs we just added we know we're a-ok.
*/
+ old_ref_mod = existing_ref->total_ref_mod;
existing->ref_mod += update->ref_mod;
+ existing_ref->total_ref_mod += update->ref_mod;
+
+ /*
+ * If we are going to from a positive ref mod to a negative or vice
+ * versa we need to make sure to adjust pending_csums accordingly.
+ */
+ if (existing_ref->is_data) {
+ if (existing_ref->total_ref_mod >= 0 && old_ref_mod < 0)
+ delayed_refs->pending_csums -= existing->num_bytes;
+ if (existing_ref->total_ref_mod < 0 && old_ref_mod >= 0)
+ delayed_refs->pending_csums += existing->num_bytes;
+ }
spin_unlock(&existing_ref->lock);
}
@@ -605,6 +620,7 @@
head_ref->is_data = is_data;
head_ref->ref_root = RB_ROOT;
head_ref->processing = 0;
+ head_ref->total_ref_mod = count_mod;
spin_lock_init(&head_ref->lock);
mutex_init(&head_ref->mutex);
@@ -614,7 +630,7 @@
existing = htree_insert(&delayed_refs->href_root,
&head_ref->href_node);
if (existing) {
- update_existing_head_ref(&existing->node, ref);
+ update_existing_head_ref(delayed_refs, &existing->node, ref);
/*
* we've updated the existing ref, free the newly
* allocated ref
@@ -622,6 +638,8 @@
kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
head_ref = existing;
} else {
+ if (is_data && count_mod < 0)
+ delayed_refs->pending_csums += num_bytes;
delayed_refs->num_heads++;
delayed_refs->num_heads_ready++;
atomic_inc(&delayed_refs->num_entries);
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index a764e23..5eb0892 100644
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -88,6 +88,14 @@
struct rb_node href_node;
struct btrfs_delayed_extent_op *extent_op;
+
+ /*
+ * This is used to track the final ref_mod from all the refs associated
+ * with this head ref, this is not adjusted as delayed refs are run,
+ * this is meant to track if we need to do the csum accounting or not.
+ */
+ int total_ref_mod;
+
/*
* when a new extent is allocated, it is just reserved in memory
* The actual extent isn't inserted into the extent allocation tree
@@ -138,6 +146,8 @@
/* total number of head nodes ready for processing */
unsigned long num_heads_ready;
+ u64 pending_csums;
+
/*
* set when the tree is flushing before a transaction commit,
* used by the throttling code to decide if new updates need
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 41e5812..a6f88eb 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2538,6 +2538,12 @@
* list before we release it.
*/
if (btrfs_delayed_ref_is_head(ref)) {
+ if (locked_ref->is_data &&
+ locked_ref->total_ref_mod < 0) {
+ spin_lock(&delayed_refs->lock);
+ delayed_refs->pending_csums -= ref->num_bytes;
+ spin_unlock(&delayed_refs->lock);
+ }
btrfs_delayed_ref_unlock(locked_ref);
locked_ref = NULL;
}
@@ -2626,11 +2632,31 @@
return div_u64(num_bytes, BTRFS_LEAF_DATA_SIZE(root));
}
+/*
+ * Takes the number of bytes to be csumm'ed and figures out how many leaves it
+ * would require to store the csums for that many bytes.
+ */
+static u64 csum_bytes_to_leaves(struct btrfs_root *root, u64 csum_bytes)
+{
+ u64 csum_size;
+ u64 num_csums_per_leaf;
+ u64 num_csums;
+
+ csum_size = BTRFS_LEAF_DATA_SIZE(root) - sizeof(struct btrfs_item);
+ num_csums_per_leaf = div64_u64(csum_size,
+ (u64)btrfs_super_csum_size(root->fs_info->super_copy));
+ num_csums = div64_u64(csum_bytes, root->sectorsize);
+ num_csums += num_csums_per_leaf - 1;
+ num_csums = div64_u64(num_csums, num_csums_per_leaf);
+ return num_csums;
+}
+
int btrfs_check_space_for_delayed_refs(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_block_rsv *global_rsv;
u64 num_heads = trans->transaction->delayed_refs.num_heads_ready;
+ u64 csum_bytes = trans->transaction->delayed_refs.pending_csums;
u64 num_bytes;
int ret = 0;
@@ -2639,6 +2665,7 @@
if (num_heads > 1)
num_bytes += (num_heads - 1) * root->nodesize;
num_bytes <<= 1;
+ num_bytes += csum_bytes_to_leaves(root, csum_bytes) * root->nodesize;
global_rsv = &root->fs_info->global_block_rsv;
/*
@@ -5065,30 +5092,19 @@
int reserve)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
- u64 csum_size;
- int num_csums_per_leaf;
- int num_csums;
- int old_csums;
+ u64 old_csums, num_csums;
if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM &&
BTRFS_I(inode)->csum_bytes == 0)
return 0;
- old_csums = (int)div_u64(BTRFS_I(inode)->csum_bytes, root->sectorsize);
+ old_csums = csum_bytes_to_leaves(root, BTRFS_I(inode)->csum_bytes);
+
if (reserve)
BTRFS_I(inode)->csum_bytes += num_bytes;
else
BTRFS_I(inode)->csum_bytes -= num_bytes;
- csum_size = BTRFS_LEAF_DATA_SIZE(root) - sizeof(struct btrfs_item);
- num_csums_per_leaf = (int)div_u64(csum_size,
- sizeof(struct btrfs_csum_item) +
- sizeof(struct btrfs_disk_key));
- num_csums = (int)div_u64(BTRFS_I(inode)->csum_bytes, root->sectorsize);
- num_csums = num_csums + num_csums_per_leaf - 1;
- num_csums = num_csums / num_csums_per_leaf;
-
- old_csums = old_csums + num_csums_per_leaf - 1;
- old_csums = old_csums / num_csums_per_leaf;
+ num_csums = csum_bytes_to_leaves(root, BTRFS_I(inode)->csum_bytes);
/* No change, no need to reserve more */
if (old_csums == num_csums)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e3fe137f..cec23cf 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4197,9 +4197,10 @@
int extent_type = -1;
int ret;
int err = 0;
- int be_nice = 0;
u64 ino = btrfs_ino(inode);
u64 bytes_deleted = 0;
+ bool be_nice = 0;
+ bool should_throttle = 0;
BUG_ON(new_size > 0 && min_type != BTRFS_EXTENT_DATA_KEY);
@@ -4405,19 +4406,20 @@
btrfs_header_owner(leaf),
ino, extent_offset, 0);
BUG_ON(ret);
- if (be_nice && pending_del_nr &&
- (pending_del_nr % 16 == 0) &&
- bytes_deleted > 1024 * 1024) {
+ if (btrfs_should_throttle_delayed_refs(trans, root))
btrfs_async_run_delayed_refs(root,
trans->delayed_ref_updates * 2, 0);
- }
}
if (found_type == BTRFS_INODE_ITEM_KEY)
break;
+ should_throttle =
+ btrfs_should_throttle_delayed_refs(trans, root);
+
if (path->slots[0] == 0 ||
- path->slots[0] != pending_del_slot) {
+ path->slots[0] != pending_del_slot ||
+ (be_nice && should_throttle)) {
if (pending_del_nr) {
ret = btrfs_del_items(trans, root, path,
pending_del_slot,
@@ -4430,6 +4432,15 @@
pending_del_nr = 0;
}
btrfs_release_path(path);
+ if (be_nice && should_throttle) {
+ unsigned long updates = trans->delayed_ref_updates;
+ if (updates) {
+ trans->delayed_ref_updates = 0;
+ ret = btrfs_run_delayed_refs(trans, root, updates * 2);
+ if (ret && !err)
+ err = ret;
+ }
+ }
goto search_again;
} else {
path->slots[0]--;
@@ -4449,7 +4460,7 @@
btrfs_free_path(path);
- if (be_nice && bytes_deleted > 32 * 1024 * 1024) {
+ if (be_nice && btrfs_should_throttle_delayed_refs(trans, root)) {
unsigned long updates = trans->delayed_ref_updates;
if (updates) {
trans->delayed_ref_updates = 0;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index ba831ee..8b9eea8 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -64,6 +64,9 @@
if (atomic_dec_and_test(&transaction->use_count)) {
BUG_ON(!list_empty(&transaction->list));
WARN_ON(!RB_EMPTY_ROOT(&transaction->delayed_refs.href_root));
+ if (transaction->delayed_refs.pending_csums)
+ printk(KERN_ERR "pending csums is %llu\n",
+ transaction->delayed_refs.pending_csums);
while (!list_empty(&transaction->pending_chunks)) {
struct extent_map *em;
@@ -223,6 +226,7 @@
cur_trans->delayed_refs.href_root = RB_ROOT;
atomic_set(&cur_trans->delayed_refs.num_entries, 0);
cur_trans->delayed_refs.num_heads_ready = 0;
+ cur_trans->delayed_refs.pending_csums = 0;
cur_trans->delayed_refs.num_heads = 0;
cur_trans->delayed_refs.flushing = 0;
cur_trans->delayed_refs.run_delayed_start = 0;