Btrfs: Lower contention on the csum mutex

This takes the csum mutex deeper in the call chain and releases it
more often.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 51aba8cee7ce..9454e0a07c89 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -321,6 +321,7 @@ again:
         file_key.offset = offset;
         btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
 
+        mutex_lock(&BTRFS_I(inode)->csum_mutex);
         item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);
         if (!IS_ERR(item)) {
                 leaf = path->nodes[0];
@@ -367,7 +368,7 @@ again:
         ret = btrfs_search_slot(trans, root, &file_key, path,
                                 BTRFS_CRC32_SIZE, 1);
         if (ret < 0)
-                goto fail;
+                goto fail_unlock;
         if (ret == 0) {
                 BUG();
         }
@@ -411,10 +412,10 @@ insert:
         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
                                       ins_size);
         if (ret < 0)
-                goto fail;
+                goto fail_unlock;
         if (ret != 0) {
                 WARN_ON(1);
-                goto fail;
+                goto fail_unlock;
         }
 csum:
         leaf = path->nodes[0];
@@ -427,6 +428,8 @@ found:
         item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +
                                       btrfs_item_size_nr(leaf, path->slots[0]));
         eb_token = NULL;
+        mutex_unlock(&BTRFS_I(inode)->csum_mutex);
+        cond_resched();
 next_sector:
 
         if (!eb_token ||
@@ -467,13 +470,18 @@ next_sector:
                 eb_token = NULL;
         }
         btrfs_mark_buffer_dirty(path->nodes[0]);
+        cond_resched();
         if (total_bytes < sums->len) {
                 btrfs_release_path(root, path);
                 goto again;
         }
-fail:
+out:
         btrfs_free_path(path);
         return ret;
+
+fail_unlock:
+        mutex_unlock(&BTRFS_I(inode)->csum_mutex);
+        goto out;
 }
 
 int btrfs_csum_truncate(struct btrfs_trans_handle *trans,