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>

1 files changed, 13 insertions, 5 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 0d1876c76732..ee40384c394d 100644
--- 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++) {