Btrfs: avoid starting a transaction in the write path
I noticed while looking at a deadlock that we are always starting a transaction
in cow_file_range(). This isn't really needed since we only need a transaction
if we are doing an inline extent, or if the allocator needs to allocate a chunk.
So push down all the transaction start stuff to be closer to where we actually
need a transaction in all of these cases. This will hopefully reduce our write
latency when we are committing often. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 277d2c2..f1c1694d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6121,8 +6121,7 @@
* ins->offset == number of blocks
* Any available blocks before search_start are skipped.
*/
-static noinline int find_free_extent(struct btrfs_trans_handle *trans,
- struct btrfs_root *orig_root,
+static noinline int find_free_extent(struct btrfs_root *orig_root,
u64 num_bytes, u64 empty_size,
u64 hint_byte, struct btrfs_key *ins,
u64 flags)
@@ -6345,10 +6344,10 @@
block_group->full_stripe_len);
/* allocate a cluster in this block group */
- ret = btrfs_find_space_cluster(trans, root,
- block_group, last_ptr,
- search_start, num_bytes,
- aligned_cluster);
+ ret = btrfs_find_space_cluster(root, block_group,
+ last_ptr, search_start,
+ num_bytes,
+ aligned_cluster);
if (ret == 0) {
/*
* now pull our allocation out of this
@@ -6479,17 +6478,28 @@
index = 0;
loop++;
if (loop == LOOP_ALLOC_CHUNK) {
+ struct btrfs_trans_handle *trans;
+
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto out;
+ }
+
ret = do_chunk_alloc(trans, root, flags,
CHUNK_ALLOC_FORCE);
/*
* Do not bail out on ENOSPC since we
* can do more things.
*/
- if (ret < 0 && ret != -ENOSPC) {
+ if (ret < 0 && ret != -ENOSPC)
btrfs_abort_transaction(trans,
root, ret);
+ else
+ ret = 0;
+ btrfs_end_transaction(trans, root);
+ if (ret)
goto out;
- }
}
if (loop == LOOP_NO_EMPTY_SIZE) {
@@ -6553,8 +6563,7 @@
up_read(&info->groups_sem);
}
-int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
- struct btrfs_root *root,
+int btrfs_reserve_extent(struct btrfs_root *root,
u64 num_bytes, u64 min_alloc_size,
u64 empty_size, u64 hint_byte,
struct btrfs_key *ins, int is_data)
@@ -6566,8 +6575,8 @@
flags = btrfs_get_alloc_profile(root, is_data);
again:
WARN_ON(num_bytes < root->sectorsize);
- ret = find_free_extent(trans, root, num_bytes, empty_size,
- hint_byte, ins, flags);
+ ret = find_free_extent(root, num_bytes, empty_size, hint_byte, ins,
+ flags);
if (ret == -ENOSPC) {
if (!final_tried) {
@@ -6955,7 +6964,7 @@
if (IS_ERR(block_rsv))
return ERR_CAST(block_rsv);
- ret = btrfs_reserve_extent(trans, root, blocksize, blocksize,
+ ret = btrfs_reserve_extent(root, blocksize, blocksize,
empty_size, hint, &ins, 0);
if (ret) {
unuse_block_rsv(root->fs_info, block_rsv, blocksize);