Btrfs: don't preallocate metadata blocks during btrfs_search_slot
In order to avoid doing expensive extent management with tree locks held,
btrfs_search_slot will preallocate tree blocks for use by COW without
any tree locks held.
A later commit moves all of the extent allocation work for COW into
a delayed update mechanism, and this preallocation will no longer be
required.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 37f31b5..87c9038 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -254,18 +254,13 @@
* empty_size -- a hint that you plan on doing more cow. This is the size in
* bytes the allocator should try to find free next to the block it returns.
* This is just a hint and may be ignored by the allocator.
- *
- * prealloc_dest -- if you have already reserved a destination for the cow,
- * this uses that block instead of allocating a new one.
- * btrfs_alloc_reserved_extent is used to finish the allocation.
*/
static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
struct extent_buffer **cow_ret,
- u64 search_start, u64 empty_size,
- u64 prealloc_dest)
+ u64 search_start, u64 empty_size)
{
u64 parent_start;
struct extent_buffer *cow;
@@ -291,26 +286,10 @@
level = btrfs_header_level(buf);
nritems = btrfs_header_nritems(buf);
- if (prealloc_dest) {
- struct btrfs_key ins;
-
- ins.objectid = prealloc_dest;
- ins.offset = buf->len;
- ins.type = BTRFS_EXTENT_ITEM_KEY;
-
- ret = btrfs_alloc_reserved_extent(trans, root, parent_start,
- root->root_key.objectid,
- trans->transid, level, &ins);
- BUG_ON(ret);
- cow = btrfs_init_new_buffer(trans, root, prealloc_dest,
- buf->len, level);
- } else {
- cow = btrfs_alloc_free_block(trans, root, buf->len,
- parent_start,
- root->root_key.objectid,
- trans->transid, level,
- search_start, empty_size);
- }
+ cow = btrfs_alloc_free_block(trans, root, buf->len,
+ parent_start, root->root_key.objectid,
+ trans->transid, level,
+ search_start, empty_size);
if (IS_ERR(cow))
return PTR_ERR(cow);
@@ -413,7 +392,7 @@
noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
- struct extent_buffer **cow_ret, u64 prealloc_dest)
+ struct extent_buffer **cow_ret)
{
u64 search_start;
int ret;
@@ -436,7 +415,6 @@
btrfs_header_owner(buf) == root->root_key.objectid &&
!btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
*cow_ret = buf;
- WARN_ON(prealloc_dest);
return 0;
}
@@ -447,8 +425,7 @@
btrfs_set_lock_blocking(buf);
ret = __btrfs_cow_block(trans, root, buf, parent,
- parent_slot, cow_ret, search_start, 0,
- prealloc_dest);
+ parent_slot, cow_ret, search_start, 0);
return ret;
}
@@ -617,7 +594,7 @@
err = __btrfs_cow_block(trans, root, cur, parent, i,
&cur, search_start,
min(16 * blocksize,
- (end_slot - i) * blocksize), 0);
+ (end_slot - i) * blocksize));
if (err) {
btrfs_tree_unlock(cur);
free_extent_buffer(cur);
@@ -937,7 +914,7 @@
BUG_ON(!child);
btrfs_tree_lock(child);
btrfs_set_lock_blocking(child);
- ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0);
+ ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
BUG_ON(ret);
spin_lock(&root->node_lock);
@@ -979,7 +956,7 @@
btrfs_tree_lock(left);
btrfs_set_lock_blocking(left);
wret = btrfs_cow_block(trans, root, left,
- parent, pslot - 1, &left, 0);
+ parent, pslot - 1, &left);
if (wret) {
ret = wret;
goto enospc;
@@ -990,7 +967,7 @@
btrfs_tree_lock(right);
btrfs_set_lock_blocking(right);
wret = btrfs_cow_block(trans, root, right,
- parent, pslot + 1, &right, 0);
+ parent, pslot + 1, &right);
if (wret) {
ret = wret;
goto enospc;
@@ -1171,7 +1148,7 @@
wret = 1;
} else {
ret = btrfs_cow_block(trans, root, left, parent,
- pslot - 1, &left, 0);
+ pslot - 1, &left);
if (ret)
wret = 1;
else {
@@ -1222,7 +1199,7 @@
} else {
ret = btrfs_cow_block(trans, root, right,
parent, pslot + 1,
- &right, 0);
+ &right);
if (ret)
wret = 1;
else {
@@ -1492,7 +1469,6 @@
u8 lowest_level = 0;
u64 blocknr;
u64 gen;
- struct btrfs_key prealloc_block;
lowest_level = p->lowest_level;
WARN_ON(lowest_level && ins_len > 0);
@@ -1501,8 +1477,6 @@
if (ins_len < 0)
lowest_unlock = 2;
- prealloc_block.objectid = 0;
-
again:
if (p->skip_locking)
b = btrfs_root_node(root);
@@ -1529,44 +1503,11 @@
!btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
goto cow_done;
}
-
- /* ok, we have to cow, is our old prealloc the right
- * size?
- */
- if (prealloc_block.objectid &&
- prealloc_block.offset != b->len) {
- btrfs_release_path(root, p);
- btrfs_free_reserved_extent(root,
- prealloc_block.objectid,
- prealloc_block.offset);
- prealloc_block.objectid = 0;
- goto again;
- }
-
- /*
- * for higher level blocks, try not to allocate blocks
- * with the block and the parent locks held.
- */
- if (level > 0 && !prealloc_block.objectid) {
- u32 size = b->len;
- u64 hint = b->start;
-
- btrfs_release_path(root, p);
- ret = btrfs_reserve_extent(trans, root,
- size, size, 0,
- hint, (u64)-1,
- &prealloc_block, 0);
- BUG_ON(ret);
- goto again;
- }
-
btrfs_set_path_blocking(p);
wret = btrfs_cow_block(trans, root, b,
p->nodes[level + 1],
- p->slots[level + 1],
- &b, prealloc_block.objectid);
- prealloc_block.objectid = 0;
+ p->slots[level + 1], &b);
if (wret) {
free_extent_buffer(b);
ret = wret;
@@ -1743,11 +1684,6 @@
* from here on, so for now just mark it as blocking
*/
btrfs_set_path_blocking(p);
- if (prealloc_block.objectid) {
- btrfs_free_reserved_extent(root,
- prealloc_block.objectid,
- prealloc_block.offset);
- }
return ret;
}
@@ -1768,7 +1704,7 @@
int ret;
eb = btrfs_lock_root_node(root);
- ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb, 0);
+ ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb);
BUG_ON(ret);
btrfs_set_lock_blocking(eb);
@@ -1826,7 +1762,7 @@
}
ret = btrfs_cow_block(trans, root, eb, parent, slot,
- &eb, 0);
+ &eb);
BUG_ON(ret);
if (root->root_key.objectid ==
@@ -2377,7 +2313,7 @@
/* cow and double check */
ret = btrfs_cow_block(trans, root, right, upper,
- slot + 1, &right, 0);
+ slot + 1, &right);
if (ret)
goto out_unlock;
@@ -2576,7 +2512,7 @@
/* cow and double check */
ret = btrfs_cow_block(trans, root, left,
- path->nodes[1], slot - 1, &left, 0);
+ path->nodes[1], slot - 1, &left);
if (ret) {
/* we hit -ENOSPC, but it isn't fatal here */
ret = 1;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 5e1d4e3..3a37ba7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1838,7 +1838,7 @@
int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,
- struct extent_buffer **cow_ret, u64 prealloc_dest);
+ struct extent_buffer **cow_ret);
int btrfs_copy_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 4112d53..d638c54 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -463,7 +463,7 @@
btrfs_extent_post_op(trans, fs_info->tree_root);
eb = btrfs_lock_root_node(fs_info->tree_root);
- btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, 0);
+ btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
@@ -766,7 +766,7 @@
btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
old = btrfs_lock_root_node(root);
- btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
+ btrfs_cow_block(trans, root, old, NULL, 0, &old);
btrfs_copy_root(trans, root, old, &tmp, objectid);
btrfs_tree_unlock(old);