redonkable/alistair23-linux
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btrfs: Refactor check_leaf function for later expansion

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Current check_leaf() function does a good job checking key order and
item offset/size.

However it only checks from slot 0 to the last but one slot, this is
good but makes later expansion hard.

So this refactoring iterates from slot 0 to the last slot.
For key comparison, it uses a key with all 0 as initial key, so all
valid keys should be larger than that.

And for item size/offset checks, it compares current item end with
previous item offset.
For slot 0, use leaf end as a special case.

This makes later item/key offset checks and item size checks easier to
be implemented.

Also, makes check_leaf() to return -EUCLEAN other than -EIO to indicate
error.

Signed-off-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2017-08-23 16:57:56 +09:00 committed by David Sterba
parent 6018ba0a0e
commit c3267bbaa9
1 changed files with 27 additions and 23 deletions
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50
fs/btrfs/disk-io.c
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@ -553,8 +553,9 @@ static noinline int check_leaf(struct btrfs_root *root,
struct extent_buffer *leaf)
{
struct btrfs_fs_info *fs_info = root->fs_info;
/* No valid key type is 0, so all key should be larger than this key */
struct btrfs_key prev_key = {0, 0, 0};
struct btrfs_key key;
struct btrfs_key leaf_key;
u32 nritems = btrfs_header_nritems(leaf);
int slot;
@ -587,7 +588,7 @@ static noinline int check_leaf(struct btrfs_root *root,
CORRUPT("non-root leaf's nritems is 0",
leaf, check_root, 0);
free_extent_buffer(eb);
return -EIO;
return -EUCLEAN;
}
free_extent_buffer(eb);
}
@ -597,28 +598,23 @@ static noinline int check_leaf(struct btrfs_root *root,
if (nritems == 0)
return 0;
/* Check the 0 item */
if (btrfs_item_offset_nr(leaf, 0) + btrfs_item_size_nr(leaf, 0) !=
BTRFS_LEAF_DATA_SIZE(fs_info)) {
CORRUPT("invalid item offset size pair", leaf, root, 0);
return -EIO;
}
/*
* Check to make sure each items keys are in the correct order and their
* offsets make sense. We only have to loop through nritems-1 because
* we check the current slot against the next slot, which verifies the
* next slot's offset+size makes sense and that the current's slot
* offset is correct.
* Check the following things to make sure this is a good leaf, and
* leaf users won't need to bother with similar sanity checks:
*
* 1) key order
* 2) item offset and size
* No overlap, no hole, all inside the leaf.
*/
for (slot = 0; slot < nritems - 1; slot++) {
btrfs_item_key_to_cpu(leaf, &leaf_key, slot);
btrfs_item_key_to_cpu(leaf, &key, slot + 1);
for (slot = 0; slot < nritems; slot++) {
u32 item_end_expected;
btrfs_item_key_to_cpu(leaf, &key, slot);
/* Make sure the keys are in the right order */
if (btrfs_comp_cpu_keys(&leaf_key, &key) >= 0) {
if (btrfs_comp_cpu_keys(&prev_key, &key) >= 0) {
CORRUPT("bad key order", leaf, root, slot);
return -EIO;
return -EUCLEAN;
}
/*
@ -626,10 +622,14 @@ static noinline int check_leaf(struct btrfs_root *root,
* item data starts at the end of the leaf and grows towards the
* front.
*/
if (btrfs_item_offset_nr(leaf, slot) !=
btrfs_item_end_nr(leaf, slot + 1)) {
if (slot == 0)
item_end_expected = BTRFS_LEAF_DATA_SIZE(fs_info);
else
item_end_expected = btrfs_item_offset_nr(leaf,
slot - 1);
if (btrfs_item_end_nr(leaf, slot) != item_end_expected) {
CORRUPT("slot offset bad", leaf, root, slot);
return -EIO;
return -EUCLEAN;
}
/*
@ -640,8 +640,12 @@ static noinline int check_leaf(struct btrfs_root *root,
if (btrfs_item_end_nr(leaf, slot) >
BTRFS_LEAF_DATA_SIZE(fs_info)) {
CORRUPT("slot end outside of leaf", leaf, root, slot);
return -EIO;
return -EUCLEAN;
}
prev_key.objectid = key.objectid;
prev_key.type = key.type;
prev_key.offset = key.offset;
}
return 0;