Btrfs: online shrinking fixes

While shrinking the FS, the allocation functions need to make sure
they don't try to allocate bytes past the end of the FS.

nodatacow needed an extra check to force cows when the existing extents are
past the end of the FS.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 23 insertions, 9 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 660b05a4baf5..99a8b0f0d318 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -192,11 +192,13 @@ static u64 noinline find_search_start(struct btrfs_root *root,
 	u64 start = 0;
 	u64 end = 0;
 	u64 cache_miss = 0;
+	u64 total_fs_bytes;
 	int wrapped = 0;
 
 	if (!cache) {
 		goto out;
 	}
+	total_fs_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
 again:
 	ret = cache_block_group(root, cache);
 	if (ret)
@@ -223,6 +225,8 @@ again:
 		if (data != BTRFS_BLOCK_GROUP_MIXED &&
 		    start + num > cache->key.objectid + cache->key.offset)
 			goto new_group;
+		if (start + num  > total_fs_bytes)
+			goto new_group;
 		return start;
 	}
 out:
@@ -239,7 +243,7 @@ new_group:
 	last = cache->key.objectid + cache->key.offset;
 wrapped:
 	cache = btrfs_lookup_block_group(root->fs_info, last);
-	if (!cache) {
+	if (!cache || cache->key.objectid >= total_fs_bytes) {
 no_cache:
 		if (!wrapped) {
 			wrapped = 1;
@@ -287,6 +291,7 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 	u64 end;
 	u64 free_check;
 	u64 ptr;
+	u64 total_fs_bytes;
 	int bit;
 	int ret;
 	int full_search = 0;
@@ -294,6 +299,7 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 	int data_swap = 0;
 
 	block_group_cache = &info->block_group_cache;
+	total_fs_bytes = btrfs_super_total_bytes(&root->fs_info->super_copy);
 
 	if (!owner)
 		factor = 8;
@@ -306,7 +312,7 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 	else
 		bit = BLOCK_GROUP_METADATA;
 
-	if (search_start) {
+	if (search_start && search_start < total_fs_bytes) {
 		struct btrfs_block_group_cache *shint;
 		shint = btrfs_lookup_block_group(info, search_start);
 		if (shint && (shint->data == data ||
@@ -318,8 +324,8 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 			}
 		}
 	}
-	if (hint && (hint->data == data ||
-		     hint->data == BTRFS_BLOCK_GROUP_MIXED)) {
+	if (hint && hint->key.objectid < total_fs_bytes &&
+	    (hint->data == data || hint->data == BTRFS_BLOCK_GROUP_MIXED)) {
 		used = btrfs_block_group_used(&hint->item);
 		if (used + hint->pinned <
 		    div_factor(hint->key.offset, factor)) {
@@ -333,6 +339,8 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 		else
 			hint_last = search_start;
 
+		if (hint_last >= total_fs_bytes)
+			hint_last = search_start;
 		last = hint_last;
 	}
 again:
@@ -350,6 +358,9 @@ again:
 		last = cache->key.objectid + cache->key.offset;
 		used = btrfs_block_group_used(&cache->item);
 
+		if (cache->key.objectid > total_fs_bytes)
+			break;
+
 		if (full_search)
 			free_check = cache->key.offset;
 		else
@@ -1420,8 +1431,8 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
 		data = BTRFS_BLOCK_GROUP_MIXED;
 	}
 
-	if (search_end == (u64)-1)
-		search_end = btrfs_super_total_bytes(&info->super_copy);
+	search_end = min(search_end,
+			 btrfs_super_total_bytes(&info->super_copy));
 	if (hint_byte) {
 		block_group = btrfs_lookup_block_group(info, hint_byte);
 		if (!block_group)
@@ -1617,7 +1628,8 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 {
 	int ret;
 	int pending_ret;
-	u64 super_used, root_used;
+	u64 super_used;
+	u64 root_used;
 	u64 search_start = 0;
 	u64 new_hint;
 	struct btrfs_fs_info *info = root->fs_info;
@@ -1636,6 +1648,8 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 			       search_start, search_end, hint_byte, ins,
 			       trans->alloc_exclude_start,
 			       trans->alloc_exclude_nr, data);
+if (ret)
+printk("find free extent returns %d\n", ret);
 	BUG_ON(ret);
 	if (ret)
 		return ret;
@@ -2292,8 +2306,6 @@ static int noinline relocate_one_extent(struct btrfs_root *extent_root,
 	while(1) {
 		ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
 
-		BUG_ON(ret == 0);
-
 		if (ret < 0)
 			goto out;
 
@@ -2340,6 +2352,8 @@ int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
 	int progress = 0;
 
 	btrfs_set_super_total_bytes(&info->super_copy, new_size);
+	clear_extent_dirty(&info->free_space_cache, new_size, (u64)-1,
+			   GFP_NOFS);
 	block_group_cache = &info->block_group_cache;
 	path = btrfs_alloc_path();
 	root = root->fs_info->extent_root;