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Btrfs: Properly handle overlapping extent in shrink_extent_tree
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The patch fixes the overlapping extent issue in shrink_extent_tree.
It checks whether there is an overlapping extent by using
find_previous_extent. If there is an overlapping extent, it setups
key.objectid and cur_byte properly.

---

Signed-off-by: Chris Mason <[email protected]>
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@ukernel @chrismason-xx
ukernel authored and chrismason-xx committed Sep 25, 2008
1 parent d548ee5 commit 73e48b2
Showing 1 changed file with 56 additions and 84 deletions.
140 changes: 56 additions & 84 deletions fs/btrfs/extent-tree.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2317,36 +2317,6 @@ static int noinline relocate_one_extent(struct btrfs_root *extent_root,
return ret;
}

static int find_overlapping_extent(struct btrfs_root *root,
struct btrfs_path *path, u64 new_size)
{
struct btrfs_key found_key;
struct extent_buffer *leaf;
int ret;

while(1) {
if (path->slots[0] == 0) {
ret = btrfs_prev_leaf(root, path);
if (ret == 1) {
return 1;
}
if (ret < 0)
return ret;
} else {
path->slots[0]--;
}
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (found_key.type == BTRFS_EXTENT_ITEM_KEY) {
if (found_key.objectid + found_key.offset > new_size)
return 0;
else
return 1;
}
}
return 1;
}

int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
{
struct btrfs_trans_handle *trans;
Expand All @@ -2357,11 +2327,10 @@ int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
struct btrfs_fs_info *info = root->fs_info;
struct extent_map_tree *block_group_cache;
struct btrfs_key key;
struct btrfs_key found_key = { 0, 0, 0 };
struct btrfs_key found_key;
struct extent_buffer *leaf;
u32 nritems;
int ret;
int slot;

btrfs_set_super_total_bytes(&info->super_copy, new_size);
block_group_cache = &info->block_group_cache;
Expand All @@ -2372,48 +2341,54 @@ int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
again:
total_found = 0;
key.objectid = new_size;
cur_byte = key.objectid;
key.offset = 0;
key.type = 0;
while(1) {
cur_byte = key.objectid;

ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
goto out;

ret = find_previous_extent(root, path);
if (ret < 0)
goto out;
if (ret == 0) {
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (found_key.objectid + found_key.offset > new_size) {
cur_byte = found_key.objectid;
key.objectid = cur_byte;
}
}
btrfs_release_path(root, path);

while(1) {
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
goto out;
next:

leaf = path->nodes[0];
if (key.objectid == new_size - 1) {
ret = find_overlapping_extent(root, path, new_size);
if (ret != 0) {
btrfs_release_path(root, path);
ret = btrfs_search_slot(NULL, root, &key,
path, 0, 0);
if (ret < 0)
goto out;
nritems = btrfs_header_nritems(leaf);
next:
if (path->slots[0] >= nritems) {
ret = btrfs_next_leaf(root, path);
if (ret < 0)
goto out;
if (ret == 1) {
ret = 0;
break;
}
leaf = path->nodes[0];
nritems = btrfs_header_nritems(leaf);
}
nritems = btrfs_header_nritems(leaf);
ret = 0;
slot = path->slots[0];
if (slot < nritems)
btrfs_item_key_to_cpu(leaf, &found_key, slot);
if (slot == nritems ||
btrfs_key_type(&found_key) != BTRFS_EXTENT_ITEM_KEY) {

btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (btrfs_key_type(&found_key) != BTRFS_EXTENT_ITEM_KEY ||
found_key.objectid + found_key.offset <= cur_byte) {
path->slots[0]++;
if (path->slots[0] >= nritems) {
ret = btrfs_next_leaf(root, path);
if (ret < 0)
goto out;
if (ret == 1) {
ret = 0;
break;
}
}
goto next;
}
btrfs_item_key_to_cpu(leaf, &found_key, slot);
if (found_key.objectid + found_key.offset <= cur_byte)
continue;

total_found++;
cur_byte = found_key.objectid + found_key.offset;
key.objectid = cur_byte;
Expand Down Expand Up @@ -2446,33 +2421,30 @@ int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret < 0)
goto out;
bg_next:

leaf = path->nodes[0];
nritems = btrfs_header_nritems(leaf);
ret = 0;
slot = path->slots[0];
if (slot < nritems)
btrfs_item_key_to_cpu(leaf, &found_key, slot);
if (slot == nritems ||
btrfs_key_type(&found_key) != BTRFS_BLOCK_GROUP_ITEM_KEY) {
if (slot < nritems) {
printk("shrinker found key %Lu %u %Lu\n",
found_key.objectid, found_key.type,
found_key.offset);
path->slots[0]++;
}
if (path->slots[0] >= nritems) {
ret = btrfs_next_leaf(root, path);
if (ret < 0)
break;
if (ret == 1) {
ret = 0;
break;
}
bg_next:
if (path->slots[0] >= nritems) {
ret = btrfs_next_leaf(root, path);
if (ret < 0)
break;
if (ret == 1) {
ret = 0;
break;
}
leaf = path->nodes[0];
nritems = btrfs_header_nritems(leaf);
}

btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (btrfs_key_type(&found_key) != BTRFS_BLOCK_GROUP_ITEM_KEY) {
printk("shrinker found key %Lu %u %Lu\n",
found_key.objectid, found_key.type,
found_key.offset);
path->slots[0]++;
goto bg_next;
}
btrfs_item_key_to_cpu(leaf, &found_key, slot);
ret = get_state_private(&info->block_group_cache,
found_key.objectid, &ptr);
if (!ret)
Expand Down

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