Btrfs: Take the csum mutex while reading checksums

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

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3da12a4d913d..28e667052ec3 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -612,6 +612,7 @@ int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)
                 return 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)) {
                 /*
@@ -640,6 +641,7 @@ 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;