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Btrfs: memset to avoid stale content in btree leaf

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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>
This commit is contained in:
Liu Bo
2016-09-23 13:44:44 -07:00
committed by David Sterba
parent 0f5053eb90
commit 851cd173f0
3 changed files with 28 additions and 19 deletions
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18
fs/btrfs/extent_io.c
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@@ -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++) {