Btrfs: Optimize csum insertion to create larger items when possible
This reduces the number of calls to btrfs_extend_item and greatly lowers
the cpu usage while writing large files.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 10a4c74..482a2b6 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -133,17 +133,22 @@
int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
+ struct inode *inode,
u64 objectid, u64 offset,
char *data, size_t len)
{
int ret;
struct btrfs_key file_key;
struct btrfs_key found_key;
+ u64 next_offset = (u64)-1;
+ int found_next = 0;
struct btrfs_path *path;
struct btrfs_csum_item *item;
struct extent_buffer *leaf = NULL;
u64 csum_offset;
u32 csum_result = ~(u32)0;
+ u32 nritems;
+ u32 ins_size;
path = btrfs_alloc_path();
BUG_ON(!path);
@@ -168,7 +173,27 @@
goto insert;
}
} else {
+ int slot = path->slots[0] + 1;
/* we didn't find a csum item, insert one */
+ nritems = btrfs_header_nritems(path->nodes[0]);
+ if (path->slots[0] >= nritems - 1) {
+ ret = btrfs_next_leaf(root, path);
+ if (ret == 1) {
+ found_next = 1;
+ } else if (ret == 0) {
+ slot = 0;
+ } else {
+ goto insert;
+ }
+ }
+ btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
+ if (found_key.objectid != objectid ||
+ found_key.type != BTRFS_CSUM_ITEM_KEY) {
+ found_next = 1;
+ goto insert;
+ }
+ next_offset = found_key.offset;
+ found_next = 1;
goto insert;
}
@@ -211,8 +236,18 @@
insert:
btrfs_release_path(root, path);
csum_offset = 0;
+ if (found_next) {
+ u64 tmp = min((u64)i_size_read(inode), next_offset);
+ tmp -= offset + root->sectorsize - 1;
+ tmp >>= root->fs_info->sb->s_blocksize_bits;
+ tmp = max((u64)1, tmp);
+ tmp = min(tmp, (u64)MAX_CSUM_ITEMS(root));
+ ins_size = BTRFS_CRC32_SIZE * tmp;
+ } else {
+ ins_size = BTRFS_CRC32_SIZE;
+ }
ret = btrfs_insert_empty_item(trans, root, path, &file_key,
- BTRFS_CRC32_SIZE);
+ ins_size);
if (ret < 0)
goto fail;
if (ret != 0) {