/*
* deletes the csum items from the csum tree for a given
* range of bytes.
*/
int btrfs_del_csums(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 bytenr, u64 len)
{
struct btrfs_path *path;
struct btrfs_key key;
u64 end_byte = bytenr + len;
u64 csum_end;
struct extent_buffer *leaf;
int ret;
u16 csum_size =
btrfs_super_csum_size(&root->fs_info->super_copy);
int blocksize = root->sectorsize;
root = root->fs_info->csum_root;
path = btrfs_alloc_path();
while (1) {
key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
key.offset = end_byte - 1;
key.type = BTRFS_EXTENT_CSUM_KEY;
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret > 0) {
if (path->slots[0] == 0)
goto out;
path->slots[0]--;
}
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
key.type != BTRFS_EXTENT_CSUM_KEY) {
break;
}
if (key.offset >= end_byte)
break;
csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
csum_end *= blocksize;
csum_end += key.offset;
/* this csum ends before we start, we're done */
if (csum_end <= bytenr)
break;
/* delete the entire item, it is inside our range */
if (key.offset >= bytenr && csum_end <= end_byte) {
ret = btrfs_del_item(trans, root, path);
BUG_ON(ret);
} else if (key.offset < bytenr && csum_end > end_byte) {
unsigned long offset;
unsigned long shift_len;
unsigned long item_offset;
/*
* [ bytenr - len ]
* [csum ]
*
* Our bytes are in the middle of the csum,
* we need to split this item and insert a new one.
*
* But we can't drop the path because the
* csum could change, get removed, extended etc.
*
* The trick here is the max size of a csum item leaves
* enough room in the tree block for a single
* item header. So, we split the item in place,
* adding a new header pointing to the existing
* bytes. Then we loop around again and we have
* a nicely formed csum item that we can neatly
* truncate.
*/
offset = (bytenr - key.offset) / blocksize;
offset *= csum_size;
shift_len = (len / blocksize) * csum_size;
item_offset = btrfs_item_ptr_offset(leaf,
path->slots[0]);
memset_extent_buffer(leaf, 0, item_offset + offset,
shift_len);
key.offset = bytenr;
/*
* btrfs_split_item returns -EAGAIN when the
* item changed size or key
*/
ret = btrfs_split_item(trans, root, path, &key, offset);
BUG_ON(ret && ret != -EAGAIN);
key.offset = end_byte - 1;
} else {
ret = truncate_one_csum(trans, root, path,
&key, bytenr, len);
BUG_ON(ret);
}
btrfs_release_path(root, path);
}
out:
btrfs_free_path(path);
return 0;
}
static int test_btrfs_split_item(u32 sectorsize, u32 nodesize)
{
struct btrfs_fs_info *fs_info;
struct btrfs_path *path = NULL;
struct btrfs_root *root = NULL;
struct extent_buffer *eb;
struct btrfs_item *item;
char *value = "mary had a little lamb";
char *split1 = "mary had a little";
char *split2 = " lamb";
char *split3 = "mary";
char *split4 = " had a little";
char buf[32];
struct btrfs_key key;
u32 value_len = strlen(value);
int ret = 0;
test_msg("Running btrfs_split_item tests\n");
fs_info = btrfs_alloc_dummy_fs_info();
if (!fs_info) {
test_msg("Could not allocate fs_info\n");
return -ENOMEM;
}
root = btrfs_alloc_dummy_root(fs_info, sectorsize, nodesize);
if (IS_ERR(root)) {
test_msg("Could not allocate root\n");
ret = PTR_ERR(root);
goto out;
}
path = btrfs_alloc_path();
if (!path) {
test_msg("Could not allocate path\n");
ret = -ENOMEM;
goto out;
}
path->nodes[0] = eb = alloc_dummy_extent_buffer(NULL, nodesize,
nodesize);
if (!eb) {
test_msg("Could not allocate dummy buffer\n");
ret = -ENOMEM;
goto out;
}
path->slots[0] = 0;
key.objectid = 0;
key.type = BTRFS_EXTENT_CSUM_KEY;
key.offset = 0;
setup_items_for_insert(root, path, &key, &value_len, value_len,
value_len + sizeof(struct btrfs_item), 1);
item = btrfs_item_nr(0);
write_extent_buffer(eb, value, btrfs_item_ptr_offset(eb, 0),
value_len);
key.offset = 3;
/*
* Passing NULL trans here should be safe because we have plenty of
* space in this leaf to split the item without having to split the
* leaf.
*/
ret = btrfs_split_item(NULL, root, path, &key, 17);
if (ret) {
test_msg("Split item failed %d\n", ret);
goto out;
}
/*
* Read the first slot, it should have the original key and contain only
* 'mary had a little'
*/
btrfs_item_key_to_cpu(eb, &key, 0);
if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
key.offset != 0) {
test_msg("Invalid key at slot 0\n");
ret = -EINVAL;
goto out;
}
item = btrfs_item_nr(0);
if (btrfs_item_size(eb, item) != strlen(split1)) {
test_msg("Invalid len in the first split\n");
ret = -EINVAL;
goto out;
}
read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 0),
strlen(split1));
if (memcmp(buf, split1, strlen(split1))) {
test_msg("Data in the buffer doesn't match what it should "
"in the first split have='%.*s' want '%s'\n",
(int)strlen(split1), buf, split1);
ret = -EINVAL;
goto out;
}
btrfs_item_key_to_cpu(eb, &key, 1);
if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
key.offset != 3) {
test_msg("Invalid key at slot 1\n");
ret = -EINVAL;
goto out;
}
item = btrfs_item_nr(1);
if (btrfs_item_size(eb, item) != strlen(split2)) {
test_msg("Invalid len in the second split\n");
ret = -EINVAL;
goto out;
}
read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 1),
strlen(split2));
if (memcmp(buf, split2, strlen(split2))) {
test_msg("Data in the buffer doesn't match what it should "
"in the second split\n");
ret = -EINVAL;
goto out;
}
key.offset = 1;
/* Do it again so we test memmoving the other items in the leaf */
ret = btrfs_split_item(NULL, root, path, &key, 4);
if (ret) {
test_msg("Second split item failed %d\n", ret);
goto out;
}
btrfs_item_key_to_cpu(eb, &key, 0);
if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
key.offset != 0) {
test_msg("Invalid key at slot 0\n");
ret = -EINVAL;
goto out;
}
item = btrfs_item_nr(0);
if (btrfs_item_size(eb, item) != strlen(split3)) {
test_msg("Invalid len in the first split\n");
ret = -EINVAL;
goto out;
}
read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 0),
strlen(split3));
if (memcmp(buf, split3, strlen(split3))) {
test_msg("Data in the buffer doesn't match what it should "
"in the third split");
ret = -EINVAL;
goto out;
}
btrfs_item_key_to_cpu(eb, &key, 1);
if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
key.offset != 1) {
test_msg("Invalid key at slot 1\n");
ret = -EINVAL;
goto out;
}
item = btrfs_item_nr(1);
if (btrfs_item_size(eb, item) != strlen(split4)) {
test_msg("Invalid len in the second split\n");
ret = -EINVAL;
goto out;
}
read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 1),
strlen(split4));
if (memcmp(buf, split4, strlen(split4))) {
test_msg("Data in the buffer doesn't match what it should "
"in the fourth split\n");
ret = -EINVAL;
goto out;
}
btrfs_item_key_to_cpu(eb, &key, 2);
if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
key.offset != 3) {
test_msg("Invalid key at slot 2\n");
ret = -EINVAL;
goto out;
}
item = btrfs_item_nr(2);
if (btrfs_item_size(eb, item) != strlen(split2)) {
test_msg("Invalid len in the second split\n");
ret = -EINVAL;
goto out;
}
read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 2),
strlen(split2));
if (memcmp(buf, split2, strlen(split2))) {
test_msg("Data in the buffer doesn't match what it should "
"in the last chunk\n");
ret = -EINVAL;
goto out;
}
out:
btrfs_free_path(path);
btrfs_free_dummy_root(root);
btrfs_free_dummy_fs_info(fs_info);
return ret;
}
