Josef Bacik
2014-Oct-03 14:38 UTC
[PATCH] Btrfs-progs: add shift_items to btrfs-corrupt-block V2
A user had a corrupted fs where his items where shifted oddly. This adds the
functionality I needed to btrfs-corrupt-block in order to reproduce this
corruption in order to make fsck fix this sort of problem. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
---
V1->V2: fix shift issue, we need to use btrfs_leaf_data() in our math.
btrfs-corrupt-block.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/btrfs-corrupt-block.c b/btrfs-corrupt-block.c
index 474d48f..bb735cc 100644
--- a/btrfs-corrupt-block.c
+++ b/btrfs-corrupt-block.c
@@ -303,6 +303,7 @@ enum btrfs_file_extent_field {
enum btrfs_metadata_block_field {
BTRFS_METADATA_BLOCK_GENERATION,
+ BTRFS_METADATA_BLOCK_SHIFT_ITEMS,
BTRFS_METADATA_BLOCK_BAD,
};
@@ -332,6 +333,8 @@ convert_metadata_block_field(char *field)
{
if (!strncmp(field, "generation", FIELD_BUF_LEN))
return BTRFS_METADATA_BLOCK_GENERATION;
+ if (!strncmp(field, "shift_items", FIELD_BUF_LEN))
+ return BTRFS_METADATA_BLOCK_SHIFT_ITEMS;
return BTRFS_METADATA_BLOCK_BAD;
}
@@ -538,6 +541,27 @@ out:
return ret;
}
+static void shift_items(struct btrfs_root *root, struct extent_buffer *eb)
+{
+ int nritems = btrfs_header_nritems(eb);
+ int shift_space = btrfs_leaf_free_space(root, eb) / 2;
+ int slot = nritems / 2;
+ int i = 0;
+ unsigned int data_end = btrfs_item_offset_nr(eb, nritems - 1);
+
+ /* Shift the item data up to and including slot back by shift space */
+ memmove_extent_buffer(eb, btrfs_leaf_data(eb) + data_end - shift_space,
+ btrfs_leaf_data(eb) + data_end,
+ btrfs_item_offset_nr(eb, slot - 1) - data_end);
+
+ /* Now update the item pointers. */
+ for (i = nritems - 1; i >= slot; i--) {
+ u32 offset = btrfs_item_offset_nr(eb, i);
+ offset -= shift_space;
+ btrfs_set_item_offset(eb, btrfs_item_nr(i), offset);
+ }
+}
+
static int corrupt_metadata_block(struct btrfs_root *root, u64 block,
char *field)
{
@@ -608,6 +632,9 @@ static int corrupt_metadata_block(struct btrfs_root *root,
u64 block,
bogus = generate_u64(orig);
btrfs_set_header_generation(eb, bogus);
break;
+ case BTRFS_METADATA_BLOCK_SHIFT_ITEMS:
+ shift_items(root, path->nodes[level]);
+ break;
default:
ret = -EINVAL;
break;
--
1.8.3.1
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