Btrfs: fix race in check-integrity caused by usage of bitfield

[firefly-linux-kernel-4.4.55.git] / fs / btrfs / free-space-cache.c

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 1027b854b90cec02b9d2328804bc12f23f9bc00b..efdd1d3f441c9659154a2464fdb7991556562ea7 100644 (file)
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -307,7 +307,6 @@ static void io_ctl_unmap_page(struct io_ctl *io_ctl)
 
 static void io_ctl_map_page(struct io_ctl *io_ctl, int clear)
 {
-       WARN_ON(io_ctl->cur);
        BUG_ON(io_ctl->index >= io_ctl->num_pages);
        io_ctl->page = io_ctl->pages[io_ctl->index++];
        io_ctl->cur = kmap(io_ctl->page);
@@ -1250,18 +1249,13 @@ tree_search_offset(struct btrfs_free_space_ctl *ctl,
                         * if previous extent entry covers the offset,
                         * we should return it instead of the bitmap entry
                         */
-                       n = &entry->offset_index;
-                       while (1) {
-                               n = rb_prev(n);
-                               if (!n)
-                                       break;
+                       n = rb_prev(&entry->offset_index);
+                       if (n) {
                                prev = rb_entry(n, struct btrfs_free_space,
                                                offset_index);
-                               if (!prev->bitmap) {
-                                       if (prev->offset + prev->bytes > offset)
-                                               entry = prev;
-                                       break;
-                               }
+                               if (!prev->bitmap &&
+                                   prev->offset + prev->bytes > offset)
+                                       entry = prev;
                        }
                }
                return entry;
@@ -1287,18 +1281,13 @@ tree_search_offset(struct btrfs_free_space_ctl *ctl,
        }
 
        if (entry->bitmap) {
-               n = &entry->offset_index;
-               while (1) {
-                       n = rb_prev(n);
-                       if (!n)
-                               break;
+               n = rb_prev(&entry->offset_index);
+               if (n) {
                        prev = rb_entry(n, struct btrfs_free_space,
                                        offset_index);
-                       if (!prev->bitmap) {
-                               if (prev->offset + prev->bytes > offset)
-                                       return prev;
-                               break;
-                       }
+                       if (!prev->bitmap &&
+                           prev->offset + prev->bytes > offset)
+                               return prev;
                }
                if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
                        return entry;