Btrfs: memset to avoid stale content in btree leaf

This is an additional patch to
"Btrfs: memset to avoid stale content in btree node block".

This uses memset to initialize the unused space in a leaf to avoid
potential stale content, which may be incurred by pushing items
between sibling leaves.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 284cc9d..8f67a14 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1715,20 +1715,6 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
        return err;
 }
 
-/*
- * The leaf data grows from end-to-front in the node.
- * this returns the address of the start of the last item,
- * which is the stop of the leaf data stack
- */
-static inline unsigned int leaf_data_end(struct btrfs_root *root,
-                                        struct extent_buffer *leaf)
-{
-       u32 nr = btrfs_header_nritems(leaf);
-       if (nr == 0)
-               return BTRFS_LEAF_DATA_SIZE(root);
-       return btrfs_item_offset_nr(leaf, nr - 1);
-}
-
 
 /*
  * search for key in the extent_buffer.  The items start at offset p,

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index cb0ae90..5f1408b 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2293,6 +2293,21 @@ static inline unsigned long btrfs_leaf_data(struct extent_buffer *l)
        return offsetof(struct btrfs_leaf, items);
 }
 
+/*
+ * The leaf data grows from end-to-front in the node.
+ * this returns the address of the start of the last item,
+ * which is the stop of the leaf data stack
+ */
+static inline unsigned int leaf_data_end(struct btrfs_root *root,
+                                        struct extent_buffer *leaf)
+{
+       u32 nr = btrfs_header_nritems(leaf);
+
+       if (nr == 0)
+               return BTRFS_LEAF_DATA_SIZE(root);
+       return btrfs_item_offset_nr(leaf, nr - 1);
+}
+
 /* struct btrfs_file_extent_item */
 BTRFS_SETGET_FUNCS(file_extent_type, struct btrfs_file_extent_item, type, 8);
 BTRFS_SETGET_STACK_FUNCS(stack_file_extent_disk_bytenr,

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 0d1876c..ee40384 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3725,8 +3725,10 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
        struct block_device *bdev = fs_info->fs_devices->latest_bdev;
        struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
        u64 offset = eb->start;
+       u32 nritems;
        unsigned long i, num_pages;
        unsigned long bio_flags = 0;
+       unsigned long start, end;
        int write_flags = (epd->sync_io ? WRITE_SYNC : 0) | REQ_META;
        int ret = 0;
 
@@ -3736,15 +3738,21 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
        if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
                bio_flags = EXTENT_BIO_TREE_LOG;
 
-       /* set btree node beyond nritems with 0 to avoid stale content */
+       /* set btree blocks beyond nritems with 0 to avoid stale content. */
+       nritems = btrfs_header_nritems(eb);
        if (btrfs_header_level(eb) > 0) {
-               u32 nritems;
-               unsigned long end;
-
-               nritems = btrfs_header_nritems(eb);
                end = btrfs_node_key_ptr_offset(nritems);
 
                memset_extent_buffer(eb, 0, end, eb->len - end);
+       } else {
+               /*
+                * leaf:
+                * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0
+                */
+               start = btrfs_item_nr_offset(nritems);
+               end = btrfs_leaf_data(eb) +
+                     leaf_data_end(fs_info->tree_root, eb);
+               memset_extent_buffer(eb, 0, start, end - start);
        }
 
        for (i = 0; i < num_pages; i++) {