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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>
This commit is contained in:
Chris Mason
parent
8e0ee43bc2
commit
9fa8cfe706
100
fs/btrfs/ctree.c
100
fs/btrfs/ctree.c
@ -254,18 +254,13 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
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* empty_size -- a hint that you plan on doing more cow. This is the size in
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* bytes the allocator should try to find free next to the block it returns.
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* This is just a hint and may be ignored by the allocator.
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*
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* prealloc_dest -- if you have already reserved a destination for the cow,
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* this uses that block instead of allocating a new one.
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* btrfs_alloc_reserved_extent is used to finish the allocation.
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*/
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static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct extent_buffer *buf,
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struct extent_buffer *parent, int parent_slot,
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struct extent_buffer **cow_ret,
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u64 search_start, u64 empty_size,
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u64 prealloc_dest)
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u64 search_start, u64 empty_size)
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{
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u64 parent_start;
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struct extent_buffer *cow;
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@ -291,26 +286,10 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
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level = btrfs_header_level(buf);
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nritems = btrfs_header_nritems(buf);
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if (prealloc_dest) {
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struct btrfs_key ins;
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ins.objectid = prealloc_dest;
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ins.offset = buf->len;
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ins.type = BTRFS_EXTENT_ITEM_KEY;
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ret = btrfs_alloc_reserved_extent(trans, root, parent_start,
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root->root_key.objectid,
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trans->transid, level, &ins);
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BUG_ON(ret);
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cow = btrfs_init_new_buffer(trans, root, prealloc_dest,
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buf->len, level);
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} else {
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cow = btrfs_alloc_free_block(trans, root, buf->len,
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parent_start,
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root->root_key.objectid,
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trans->transid, level,
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search_start, empty_size);
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}
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cow = btrfs_alloc_free_block(trans, root, buf->len,
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parent_start, root->root_key.objectid,
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trans->transid, level,
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search_start, empty_size);
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if (IS_ERR(cow))
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return PTR_ERR(cow);
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@ -413,7 +392,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
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noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, struct extent_buffer *buf,
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struct extent_buffer *parent, int parent_slot,
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struct extent_buffer **cow_ret, u64 prealloc_dest)
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struct extent_buffer **cow_ret)
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{
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u64 search_start;
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int ret;
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@ -436,7 +415,6 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
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btrfs_header_owner(buf) == root->root_key.objectid &&
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!btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
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*cow_ret = buf;
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WARN_ON(prealloc_dest);
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return 0;
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}
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@ -447,8 +425,7 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
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btrfs_set_lock_blocking(buf);
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ret = __btrfs_cow_block(trans, root, buf, parent,
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parent_slot, cow_ret, search_start, 0,
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prealloc_dest);
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parent_slot, cow_ret, search_start, 0);
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return ret;
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}
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@ -617,7 +594,7 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
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err = __btrfs_cow_block(trans, root, cur, parent, i,
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&cur, search_start,
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min(16 * blocksize,
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(end_slot - i) * blocksize), 0);
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(end_slot - i) * blocksize));
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if (err) {
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btrfs_tree_unlock(cur);
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free_extent_buffer(cur);
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@ -937,7 +914,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
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BUG_ON(!child);
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btrfs_tree_lock(child);
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btrfs_set_lock_blocking(child);
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ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0);
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ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
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BUG_ON(ret);
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spin_lock(&root->node_lock);
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@ -979,7 +956,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
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btrfs_tree_lock(left);
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btrfs_set_lock_blocking(left);
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wret = btrfs_cow_block(trans, root, left,
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parent, pslot - 1, &left, 0);
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parent, pslot - 1, &left);
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if (wret) {
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ret = wret;
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goto enospc;
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@ -990,7 +967,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
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btrfs_tree_lock(right);
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btrfs_set_lock_blocking(right);
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wret = btrfs_cow_block(trans, root, right,
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parent, pslot + 1, &right, 0);
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parent, pslot + 1, &right);
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if (wret) {
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ret = wret;
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goto enospc;
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@ -1171,7 +1148,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
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wret = 1;
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} else {
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ret = btrfs_cow_block(trans, root, left, parent,
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pslot - 1, &left, 0);
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pslot - 1, &left);
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if (ret)
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wret = 1;
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else {
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@ -1222,7 +1199,7 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
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} else {
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ret = btrfs_cow_block(trans, root, right,
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parent, pslot + 1,
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&right, 0);
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&right);
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if (ret)
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wret = 1;
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else {
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@ -1492,7 +1469,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
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u8 lowest_level = 0;
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u64 blocknr;
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u64 gen;
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struct btrfs_key prealloc_block;
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lowest_level = p->lowest_level;
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WARN_ON(lowest_level && ins_len > 0);
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@ -1501,8 +1477,6 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
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if (ins_len < 0)
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lowest_unlock = 2;
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prealloc_block.objectid = 0;
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again:
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if (p->skip_locking)
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b = btrfs_root_node(root);
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@ -1529,44 +1503,11 @@ again:
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!btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
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goto cow_done;
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}
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/* ok, we have to cow, is our old prealloc the right
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* size?
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*/
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if (prealloc_block.objectid &&
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prealloc_block.offset != b->len) {
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btrfs_release_path(root, p);
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btrfs_free_reserved_extent(root,
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prealloc_block.objectid,
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prealloc_block.offset);
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prealloc_block.objectid = 0;
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goto again;
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}
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/*
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* for higher level blocks, try not to allocate blocks
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* with the block and the parent locks held.
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*/
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if (level > 0 && !prealloc_block.objectid) {
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u32 size = b->len;
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u64 hint = b->start;
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btrfs_release_path(root, p);
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ret = btrfs_reserve_extent(trans, root,
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size, size, 0,
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hint, (u64)-1,
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&prealloc_block, 0);
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BUG_ON(ret);
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goto again;
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}
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btrfs_set_path_blocking(p);
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wret = btrfs_cow_block(trans, root, b,
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p->nodes[level + 1],
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p->slots[level + 1],
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&b, prealloc_block.objectid);
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prealloc_block.objectid = 0;
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p->slots[level + 1], &b);
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if (wret) {
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free_extent_buffer(b);
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ret = wret;
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@ -1743,11 +1684,6 @@ done:
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* from here on, so for now just mark it as blocking
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*/
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btrfs_set_path_blocking(p);
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if (prealloc_block.objectid) {
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btrfs_free_reserved_extent(root,
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prealloc_block.objectid,
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prealloc_block.offset);
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}
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return ret;
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}
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@ -1768,7 +1704,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans,
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int ret;
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eb = btrfs_lock_root_node(root);
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ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb, 0);
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ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb);
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BUG_ON(ret);
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btrfs_set_lock_blocking(eb);
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@ -1826,7 +1762,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans,
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}
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ret = btrfs_cow_block(trans, root, eb, parent, slot,
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&eb, 0);
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&eb);
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BUG_ON(ret);
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if (root->root_key.objectid ==
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@ -2377,7 +2313,7 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
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/* cow and double check */
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ret = btrfs_cow_block(trans, root, right, upper,
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slot + 1, &right, 0);
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slot + 1, &right);
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if (ret)
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goto out_unlock;
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@ -2576,7 +2512,7 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
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/* cow and double check */
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ret = btrfs_cow_block(trans, root, left,
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path->nodes[1], slot - 1, &left, 0);
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path->nodes[1], slot - 1, &left);
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if (ret) {
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/* we hit -ENOSPC, but it isn't fatal here */
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ret = 1;
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@ -1838,7 +1838,7 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
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int btrfs_cow_block(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, struct extent_buffer *buf,
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struct extent_buffer *parent, int parent_slot,
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struct extent_buffer **cow_ret, u64 prealloc_dest);
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struct extent_buffer **cow_ret);
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int btrfs_copy_root(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct extent_buffer *buf,
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@ -463,7 +463,7 @@ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
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btrfs_extent_post_op(trans, fs_info->tree_root);
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eb = btrfs_lock_root_node(fs_info->tree_root);
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btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, 0);
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btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
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btrfs_tree_unlock(eb);
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free_extent_buffer(eb);
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@ -766,7 +766,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
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btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
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old = btrfs_lock_root_node(root);
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btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
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btrfs_cow_block(trans, root, old, NULL, 0, &old);
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btrfs_copy_root(trans, root, old, &tmp, objectid);
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btrfs_tree_unlock(old);
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