1 files changed, 18 insertions, 15 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 28e667052ec3..0e90315ea803 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -611,22 +611,25 @@ int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)
             btrfs_test_flag(inode, NODATASUM))
                 return 0;
 
+        /*
+         * It is possible there is an ordered extent that has
+         * not yet finished for this range in the file.  If so,
+         * that extent will have a csum cached, and it will insert
+         * the sum after all the blocks in the extent are fully
+         * on disk.  So, look for an ordered extent and use the
+         * sum if found.  We have to do this before looking in the
+         * btree because csum items are pre-inserted based on
+         * the file size.  btrfs_lookup_csum might find an item
+         * that still hasn't been fully filled.
+         */
+        ret = btrfs_find_ordered_sum(inode, start, &csum);
+        if (ret == 0)
+                goto found;
+
+        ret = 0;
         path = btrfs_alloc_path();
-        mutex_lock(&BTRFS_I(inode)->csum_mutex);
         item = btrfs_lookup_csum(NULL, root, path, inode->i_ino, start, 0);
         if (IS_ERR(item)) {
-                /*
-                 * It is possible there is an ordered extent that has
-                 * not yet finished for this range in the file.  If so,
-                 * that extent will have a csum cached, and it will insert
-                 * the sum after all the blocks in the extent are fully
-                 * on disk.  So, look for an ordered extent and use the
-                 * sum if found.
-                 */
-                ret = btrfs_find_ordered_sum(inode, start, &csum);
-                if (ret == 0)
-                        goto found;
-
                 ret = PTR_ERR(item);
                 /* a csum that isn't present is a preallocated region. */
                 if (ret == -ENOENT || ret == -EFBIG)
@@ -641,7 +644,6 @@ int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)
 found:
         set_state_private(io_tree, start, csum);
 out:
-        mutex_unlock(&BTRFS_I(inode)->csum_mutex);
         if (path)
                 btrfs_free_path(path);
         return ret;
@@ -1375,7 +1377,7 @@ again:
                 }
                 if (!PageUptodate(page)) {
                         ret = -EIO;
-                        goto out;
+                        goto out_unlock;
                 }
         }
         wait_on_page_writeback(page);
@@ -1406,6 +1408,7 @@ again:
         set_page_dirty(page);
         unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
 
+out_unlock:
         unlock_page(page);
         page_cache_release(page);
 out: