diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/btrfs/free-space-tree.c | 1585 |
1 files changed, 1585 insertions, 0 deletions
diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c new file mode 100644 index 000000000..6cf2f7bb3 --- /dev/null +++ b/fs/btrfs/free-space-tree.c @@ -0,0 +1,1585 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015 Facebook. All rights reserved. + */ + +#include <linux/kernel.h> +#include <linux/sched/mm.h> +#include "ctree.h" +#include "disk-io.h" +#include "locking.h" +#include "free-space-tree.h" +#include "transaction.h" +#include "block-group.h" + +static int __add_block_group_free_space(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path); + +void set_free_space_tree_thresholds(struct btrfs_block_group *cache) +{ + u32 bitmap_range; + size_t bitmap_size; + u64 num_bitmaps, total_bitmap_size; + + if (WARN_ON(cache->length == 0)) + btrfs_warn(cache->fs_info, "block group %llu length is zero", + cache->start); + + /* + * We convert to bitmaps when the disk space required for using extents + * exceeds that required for using bitmaps. + */ + bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS; + num_bitmaps = div_u64(cache->length + bitmap_range - 1, bitmap_range); + bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE; + total_bitmap_size = num_bitmaps * bitmap_size; + cache->bitmap_high_thresh = div_u64(total_bitmap_size, + sizeof(struct btrfs_item)); + + /* + * We allow for a small buffer between the high threshold and low + * threshold to avoid thrashing back and forth between the two formats. + */ + if (cache->bitmap_high_thresh > 100) + cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100; + else + cache->bitmap_low_thresh = 0; +} + +static int add_new_free_space_info(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path) +{ + struct btrfs_root *root = trans->fs_info->free_space_root; + struct btrfs_free_space_info *info; + struct btrfs_key key; + struct extent_buffer *leaf; + int ret; + + key.objectid = block_group->start; + key.type = BTRFS_FREE_SPACE_INFO_KEY; + key.offset = block_group->length; + + ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info)); + if (ret) + goto out; + + leaf = path->nodes[0]; + info = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_free_space_info); + btrfs_set_free_space_extent_count(leaf, info, 0); + btrfs_set_free_space_flags(leaf, info, 0); + btrfs_mark_buffer_dirty(leaf); + + ret = 0; +out: + btrfs_release_path(path); + return ret; +} + +EXPORT_FOR_TESTS +struct btrfs_free_space_info *search_free_space_info( + struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path, int cow) +{ + struct btrfs_fs_info *fs_info = block_group->fs_info; + struct btrfs_root *root = fs_info->free_space_root; + struct btrfs_key key; + int ret; + + key.objectid = block_group->start; + key.type = BTRFS_FREE_SPACE_INFO_KEY; + key.offset = block_group->length; + + ret = btrfs_search_slot(trans, root, &key, path, 0, cow); + if (ret < 0) + return ERR_PTR(ret); + if (ret != 0) { + btrfs_warn(fs_info, "missing free space info for %llu", + block_group->start); + ASSERT(0); + return ERR_PTR(-ENOENT); + } + + return btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_free_space_info); +} + +/* + * btrfs_search_slot() but we're looking for the greatest key less than the + * passed key. + */ +static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct btrfs_key *key, struct btrfs_path *p, + int ins_len, int cow) +{ + int ret; + + ret = btrfs_search_slot(trans, root, key, p, ins_len, cow); + if (ret < 0) + return ret; + + if (ret == 0) { + ASSERT(0); + return -EIO; + } + + if (p->slots[0] == 0) { + ASSERT(0); + return -EIO; + } + p->slots[0]--; + + return 0; +} + +static inline u32 free_space_bitmap_size(u64 size, u32 sectorsize) +{ + return DIV_ROUND_UP((u32)div_u64(size, sectorsize), BITS_PER_BYTE); +} + +static unsigned long *alloc_bitmap(u32 bitmap_size) +{ + unsigned long *ret; + unsigned int nofs_flag; + u32 bitmap_rounded_size = round_up(bitmap_size, sizeof(unsigned long)); + + /* + * GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse + * into the filesystem as the free space bitmap can be modified in the + * critical section of a transaction commit. + * + * TODO: push the memalloc_nofs_{save,restore}() to the caller where we + * know that recursion is unsafe. + */ + nofs_flag = memalloc_nofs_save(); + ret = kvzalloc(bitmap_rounded_size, GFP_KERNEL); + memalloc_nofs_restore(nofs_flag); + return ret; +} + +static void le_bitmap_set(unsigned long *map, unsigned int start, int len) +{ + u8 *p = ((u8 *)map) + BIT_BYTE(start); + const unsigned int size = start + len; + int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE); + u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start); + + while (len - bits_to_set >= 0) { + *p |= mask_to_set; + len -= bits_to_set; + bits_to_set = BITS_PER_BYTE; + mask_to_set = ~0; + p++; + } + if (len) { + mask_to_set &= BITMAP_LAST_BYTE_MASK(size); + *p |= mask_to_set; + } +} + +EXPORT_FOR_TESTS +int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_root *root = fs_info->free_space_root; + struct btrfs_free_space_info *info; + struct btrfs_key key, found_key; + struct extent_buffer *leaf; + unsigned long *bitmap; + char *bitmap_cursor; + u64 start, end; + u64 bitmap_range, i; + u32 bitmap_size, flags, expected_extent_count; + u32 extent_count = 0; + int done = 0, nr; + int ret; + + bitmap_size = free_space_bitmap_size(block_group->length, + fs_info->sectorsize); + bitmap = alloc_bitmap(bitmap_size); + if (!bitmap) { + ret = -ENOMEM; + goto out; + } + + start = block_group->start; + end = block_group->start + block_group->length; + + key.objectid = end - 1; + key.type = (u8)-1; + key.offset = (u64)-1; + + while (!done) { + ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1); + if (ret) + goto out; + + leaf = path->nodes[0]; + nr = 0; + path->slots[0]++; + while (path->slots[0] > 0) { + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1); + + if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) { + ASSERT(found_key.objectid == block_group->start); + ASSERT(found_key.offset == block_group->length); + done = 1; + break; + } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) { + u64 first, last; + + ASSERT(found_key.objectid >= start); + ASSERT(found_key.objectid < end); + ASSERT(found_key.objectid + found_key.offset <= end); + + first = div_u64(found_key.objectid - start, + fs_info->sectorsize); + last = div_u64(found_key.objectid + found_key.offset - start, + fs_info->sectorsize); + le_bitmap_set(bitmap, first, last - first); + + extent_count++; + nr++; + path->slots[0]--; + } else { + ASSERT(0); + } + } + + ret = btrfs_del_items(trans, root, path, path->slots[0], nr); + if (ret) + goto out; + btrfs_release_path(path); + } + + info = search_free_space_info(trans, block_group, path, 1); + if (IS_ERR(info)) { + ret = PTR_ERR(info); + goto out; + } + leaf = path->nodes[0]; + flags = btrfs_free_space_flags(leaf, info); + flags |= BTRFS_FREE_SPACE_USING_BITMAPS; + btrfs_set_free_space_flags(leaf, info, flags); + expected_extent_count = btrfs_free_space_extent_count(leaf, info); + btrfs_mark_buffer_dirty(leaf); + btrfs_release_path(path); + + if (extent_count != expected_extent_count) { + btrfs_err(fs_info, + "incorrect extent count for %llu; counted %u, expected %u", + block_group->start, extent_count, + expected_extent_count); + ASSERT(0); + ret = -EIO; + goto out; + } + + bitmap_cursor = (char *)bitmap; + bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS; + i = start; + while (i < end) { + unsigned long ptr; + u64 extent_size; + u32 data_size; + + extent_size = min(end - i, bitmap_range); + data_size = free_space_bitmap_size(extent_size, + fs_info->sectorsize); + + key.objectid = i; + key.type = BTRFS_FREE_SPACE_BITMAP_KEY; + key.offset = extent_size; + + ret = btrfs_insert_empty_item(trans, root, path, &key, + data_size); + if (ret) + goto out; + + leaf = path->nodes[0]; + ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); + write_extent_buffer(leaf, bitmap_cursor, ptr, + data_size); + btrfs_mark_buffer_dirty(leaf); + btrfs_release_path(path); + + i += extent_size; + bitmap_cursor += data_size; + } + + ret = 0; +out: + kvfree(bitmap); + if (ret) + btrfs_abort_transaction(trans, ret); + return ret; +} + +EXPORT_FOR_TESTS +int convert_free_space_to_extents(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_root *root = fs_info->free_space_root; + struct btrfs_free_space_info *info; + struct btrfs_key key, found_key; + struct extent_buffer *leaf; + unsigned long *bitmap; + u64 start, end; + u32 bitmap_size, flags, expected_extent_count; + unsigned long nrbits, start_bit, end_bit; + u32 extent_count = 0; + int done = 0, nr; + int ret; + + bitmap_size = free_space_bitmap_size(block_group->length, + fs_info->sectorsize); + bitmap = alloc_bitmap(bitmap_size); + if (!bitmap) { + ret = -ENOMEM; + goto out; + } + + start = block_group->start; + end = block_group->start + block_group->length; + + key.objectid = end - 1; + key.type = (u8)-1; + key.offset = (u64)-1; + + while (!done) { + ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1); + if (ret) + goto out; + + leaf = path->nodes[0]; + nr = 0; + path->slots[0]++; + while (path->slots[0] > 0) { + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1); + + if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) { + ASSERT(found_key.objectid == block_group->start); + ASSERT(found_key.offset == block_group->length); + done = 1; + break; + } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) { + unsigned long ptr; + char *bitmap_cursor; + u32 bitmap_pos, data_size; + + ASSERT(found_key.objectid >= start); + ASSERT(found_key.objectid < end); + ASSERT(found_key.objectid + found_key.offset <= end); + + bitmap_pos = div_u64(found_key.objectid - start, + fs_info->sectorsize * + BITS_PER_BYTE); + bitmap_cursor = ((char *)bitmap) + bitmap_pos; + data_size = free_space_bitmap_size(found_key.offset, + fs_info->sectorsize); + + ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1); + read_extent_buffer(leaf, bitmap_cursor, ptr, + data_size); + + nr++; + path->slots[0]--; + } else { + ASSERT(0); + } + } + + ret = btrfs_del_items(trans, root, path, path->slots[0], nr); + if (ret) + goto out; + btrfs_release_path(path); + } + + info = search_free_space_info(trans, block_group, path, 1); + if (IS_ERR(info)) { + ret = PTR_ERR(info); + goto out; + } + leaf = path->nodes[0]; + flags = btrfs_free_space_flags(leaf, info); + flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS; + btrfs_set_free_space_flags(leaf, info, flags); + expected_extent_count = btrfs_free_space_extent_count(leaf, info); + btrfs_mark_buffer_dirty(leaf); + btrfs_release_path(path); + + nrbits = div_u64(block_group->length, block_group->fs_info->sectorsize); + start_bit = find_next_bit_le(bitmap, nrbits, 0); + + while (start_bit < nrbits) { + end_bit = find_next_zero_bit_le(bitmap, nrbits, start_bit); + ASSERT(start_bit < end_bit); + + key.objectid = start + start_bit * block_group->fs_info->sectorsize; + key.type = BTRFS_FREE_SPACE_EXTENT_KEY; + key.offset = (end_bit - start_bit) * block_group->fs_info->sectorsize; + + ret = btrfs_insert_empty_item(trans, root, path, &key, 0); + if (ret) + goto out; + btrfs_release_path(path); + + extent_count++; + + start_bit = find_next_bit_le(bitmap, nrbits, end_bit); + } + + if (extent_count != expected_extent_count) { + btrfs_err(fs_info, + "incorrect extent count for %llu; counted %u, expected %u", + block_group->start, extent_count, + expected_extent_count); + ASSERT(0); + ret = -EIO; + goto out; + } + + ret = 0; +out: + kvfree(bitmap); + if (ret) + btrfs_abort_transaction(trans, ret); + return ret; +} + +static int update_free_space_extent_count(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path, + int new_extents) +{ + struct btrfs_free_space_info *info; + u32 flags; + u32 extent_count; + int ret = 0; + + if (new_extents == 0) + return 0; + + info = search_free_space_info(trans, block_group, path, 1); + if (IS_ERR(info)) { + ret = PTR_ERR(info); + goto out; + } + flags = btrfs_free_space_flags(path->nodes[0], info); + extent_count = btrfs_free_space_extent_count(path->nodes[0], info); + + extent_count += new_extents; + btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count); + btrfs_mark_buffer_dirty(path->nodes[0]); + btrfs_release_path(path); + + if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) && + extent_count > block_group->bitmap_high_thresh) { + ret = convert_free_space_to_bitmaps(trans, block_group, path); + } else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) && + extent_count < block_group->bitmap_low_thresh) { + ret = convert_free_space_to_extents(trans, block_group, path); + } + +out: + return ret; +} + +EXPORT_FOR_TESTS +int free_space_test_bit(struct btrfs_block_group *block_group, + struct btrfs_path *path, u64 offset) +{ + struct extent_buffer *leaf; + struct btrfs_key key; + u64 found_start, found_end; + unsigned long ptr, i; + + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY); + + found_start = key.objectid; + found_end = key.objectid + key.offset; + ASSERT(offset >= found_start && offset < found_end); + + ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); + i = div_u64(offset - found_start, + block_group->fs_info->sectorsize); + return !!extent_buffer_test_bit(leaf, ptr, i); +} + +static void free_space_set_bits(struct btrfs_block_group *block_group, + struct btrfs_path *path, u64 *start, u64 *size, + int bit) +{ + struct btrfs_fs_info *fs_info = block_group->fs_info; + struct extent_buffer *leaf; + struct btrfs_key key; + u64 end = *start + *size; + u64 found_start, found_end; + unsigned long ptr, first, last; + + leaf = path->nodes[0]; + btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); + ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY); + + found_start = key.objectid; + found_end = key.objectid + key.offset; + ASSERT(*start >= found_start && *start < found_end); + ASSERT(end > found_start); + + if (end > found_end) + end = found_end; + + ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); + first = div_u64(*start - found_start, fs_info->sectorsize); + last = div_u64(end - found_start, fs_info->sectorsize); + if (bit) + extent_buffer_bitmap_set(leaf, ptr, first, last - first); + else + extent_buffer_bitmap_clear(leaf, ptr, first, last - first); + btrfs_mark_buffer_dirty(leaf); + + *size -= end - *start; + *start = end; +} + +/* + * We can't use btrfs_next_item() in modify_free_space_bitmap() because + * btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy + * tree walking in btrfs_next_leaf() anyways because we know exactly what we're + * looking for. + */ +static int free_space_next_bitmap(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct btrfs_path *p) +{ + struct btrfs_key key; + + if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) { + p->slots[0]++; + return 0; + } + + btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]); + btrfs_release_path(p); + + key.objectid += key.offset; + key.type = (u8)-1; + key.offset = (u64)-1; + + return btrfs_search_prev_slot(trans, root, &key, p, 0, 1); +} + +/* + * If remove is 1, then we are removing free space, thus clearing bits in the + * bitmap. If remove is 0, then we are adding free space, thus setting bits in + * the bitmap. + */ +static int modify_free_space_bitmap(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path, + u64 start, u64 size, int remove) +{ + struct btrfs_root *root = block_group->fs_info->free_space_root; + struct btrfs_key key; + u64 end = start + size; + u64 cur_start, cur_size; + int prev_bit, next_bit; + int new_extents; + int ret; + + /* + * Read the bit for the block immediately before the extent of space if + * that block is within the block group. + */ + if (start > block_group->start) { + u64 prev_block = start - block_group->fs_info->sectorsize; + + key.objectid = prev_block; + key.type = (u8)-1; + key.offset = (u64)-1; + + ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1); + if (ret) + goto out; + + prev_bit = free_space_test_bit(block_group, path, prev_block); + + /* The previous block may have been in the previous bitmap. */ + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + if (start >= key.objectid + key.offset) { + ret = free_space_next_bitmap(trans, root, path); + if (ret) + goto out; + } + } else { + key.objectid = start; + key.type = (u8)-1; + key.offset = (u64)-1; + + ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1); + if (ret) + goto out; + + prev_bit = -1; + } + + /* + * Iterate over all of the bitmaps overlapped by the extent of space, + * clearing/setting bits as required. + */ + cur_start = start; + cur_size = size; + while (1) { + free_space_set_bits(block_group, path, &cur_start, &cur_size, + !remove); + if (cur_size == 0) + break; + ret = free_space_next_bitmap(trans, root, path); + if (ret) + goto out; + } + + /* + * Read the bit for the block immediately after the extent of space if + * that block is within the block group. + */ + if (end < block_group->start + block_group->length) { + /* The next block may be in the next bitmap. */ + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + if (end >= key.objectid + key.offset) { + ret = free_space_next_bitmap(trans, root, path); + if (ret) + goto out; + } + + next_bit = free_space_test_bit(block_group, path, end); + } else { + next_bit = -1; + } + + if (remove) { + new_extents = -1; + if (prev_bit == 1) { + /* Leftover on the left. */ + new_extents++; + } + if (next_bit == 1) { + /* Leftover on the right. */ + new_extents++; + } + } else { + new_extents = 1; + if (prev_bit == 1) { + /* Merging with neighbor on the left. */ + new_extents--; + } + if (next_bit == 1) { + /* Merging with neighbor on the right. */ + new_extents--; + } + } + + btrfs_release_path(path); + ret = update_free_space_extent_count(trans, block_group, path, + new_extents); + +out: + return ret; +} + +static int remove_free_space_extent(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path, + u64 start, u64 size) +{ + struct btrfs_root *root = trans->fs_info->free_space_root; + struct btrfs_key key; + u64 found_start, found_end; + u64 end = start + size; + int new_extents = -1; + int ret; + + key.objectid = start; + key.type = (u8)-1; + key.offset = (u64)-1; + + ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1); + if (ret) + goto out; + + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + + ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY); + + found_start = key.objectid; + found_end = key.objectid + key.offset; + ASSERT(start >= found_start && end <= found_end); + + /* + * Okay, now that we've found the free space extent which contains the + * free space that we are removing, there are four cases: + * + * 1. We're using the whole extent: delete the key we found and + * decrement the free space extent count. + * 2. We are using part of the extent starting at the beginning: delete + * the key we found and insert a new key representing the leftover at + * the end. There is no net change in the number of extents. + * 3. We are using part of the extent ending at the end: delete the key + * we found and insert a new key representing the leftover at the + * beginning. There is no net change in the number of extents. + * 4. We are using part of the extent in the middle: delete the key we + * found and insert two new keys representing the leftovers on each + * side. Where we used to have one extent, we now have two, so increment + * the extent count. We may need to convert the block group to bitmaps + * as a result. + */ + + /* Delete the existing key (cases 1-4). */ + ret = btrfs_del_item(trans, root, path); + if (ret) + goto out; + + /* Add a key for leftovers at the beginning (cases 3 and 4). */ + if (start > found_start) { + key.objectid = found_start; + key.type = BTRFS_FREE_SPACE_EXTENT_KEY; + key.offset = start - found_start; + + btrfs_release_path(path); + ret = btrfs_insert_empty_item(trans, root, path, &key, 0); + if (ret) + goto out; + new_extents++; + } + + /* Add a key for leftovers at the end (cases 2 and 4). */ + if (end < found_end) { + key.objectid = end; + key.type = BTRFS_FREE_SPACE_EXTENT_KEY; + key.offset = found_end - end; + + btrfs_release_path(path); + ret = btrfs_insert_empty_item(trans, root, path, &key, 0); + if (ret) + goto out; + new_extents++; + } + + btrfs_release_path(path); + ret = update_free_space_extent_count(trans, block_group, path, + new_extents); + +out: + return ret; +} + +EXPORT_FOR_TESTS +int __remove_from_free_space_tree(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path, u64 start, u64 size) +{ + struct btrfs_free_space_info *info; + u32 flags; + int ret; + + if (block_group->needs_free_space) { + ret = __add_block_group_free_space(trans, block_group, path); + if (ret) + return ret; + } + + info = search_free_space_info(NULL, block_group, path, 0); + if (IS_ERR(info)) + return PTR_ERR(info); + flags = btrfs_free_space_flags(path->nodes[0], info); + btrfs_release_path(path); + + if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) { + return modify_free_space_bitmap(trans, block_group, path, + start, size, 1); + } else { + return remove_free_space_extent(trans, block_group, path, + start, size); + } +} + +int remove_from_free_space_tree(struct btrfs_trans_handle *trans, + u64 start, u64 size) +{ + struct btrfs_block_group *block_group; + struct btrfs_path *path; + int ret; + + if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE)) + return 0; + + path = btrfs_alloc_path(); + if (!path) { + ret = -ENOMEM; + goto out; + } + + block_group = btrfs_lookup_block_group(trans->fs_info, start); + if (!block_group) { + ASSERT(0); + ret = -ENOENT; + goto out; + } + + mutex_lock(&block_group->free_space_lock); + ret = __remove_from_free_space_tree(trans, block_group, path, start, + size); + mutex_unlock(&block_group->free_space_lock); + + btrfs_put_block_group(block_group); +out: + btrfs_free_path(path); + if (ret) + btrfs_abort_transaction(trans, ret); + return ret; +} + +static int add_free_space_extent(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path, + u64 start, u64 size) +{ + struct btrfs_root *root = trans->fs_info->free_space_root; + struct btrfs_key key, new_key; + u64 found_start, found_end; + u64 end = start + size; + int new_extents = 1; + int ret; + + /* + * We are adding a new extent of free space, but we need to merge + * extents. There are four cases here: + * + * 1. The new extent does not have any immediate neighbors to merge + * with: add the new key and increment the free space extent count. We + * may need to convert the block group to bitmaps as a result. + * 2. The new extent has an immediate neighbor before it: remove the + * previous key and insert a new key combining both of them. There is no + * net change in the number of extents. + * 3. The new extent has an immediate neighbor after it: remove the next + * key and insert a new key combining both of them. There is no net + * change in the number of extents. + * 4. The new extent has immediate neighbors on both sides: remove both + * of the keys and insert a new key combining all of them. Where we used + * to have two extents, we now have one, so decrement the extent count. + */ + + new_key.objectid = start; + new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY; + new_key.offset = size; + + /* Search for a neighbor on the left. */ + if (start == block_group->start) + goto right; + key.objectid = start - 1; + key.type = (u8)-1; + key.offset = (u64)-1; + + ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1); + if (ret) + goto out; + + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + + if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) { + ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY); + btrfs_release_path(path); + goto right; + } + + found_start = key.objectid; + found_end = key.objectid + key.offset; + ASSERT(found_start >= block_group->start && + found_end > block_group->start); + ASSERT(found_start < start && found_end <= start); + + /* + * Delete the neighbor on the left and absorb it into the new key (cases + * 2 and 4). + */ + if (found_end == start) { + ret = btrfs_del_item(trans, root, path); + if (ret) + goto out; + new_key.objectid = found_start; + new_key.offset += key.offset; + new_extents--; + } + btrfs_release_path(path); + +right: + /* Search for a neighbor on the right. */ + if (end == block_group->start + block_group->length) + goto insert; + key.objectid = end; + key.type = (u8)-1; + key.offset = (u64)-1; + + ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1); + if (ret) + goto out; + + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + + if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) { + ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY); + btrfs_release_path(path); + goto insert; + } + + found_start = key.objectid; + found_end = key.objectid + key.offset; + ASSERT(found_start >= block_group->start && + found_end > block_group->start); + ASSERT((found_start < start && found_end <= start) || + (found_start >= end && found_end > end)); + + /* + * Delete the neighbor on the right and absorb it into the new key + * (cases 3 and 4). + */ + if (found_start == end) { + ret = btrfs_del_item(trans, root, path); + if (ret) + goto out; + new_key.offset += key.offset; + new_extents--; + } + btrfs_release_path(path); + +insert: + /* Insert the new key (cases 1-4). */ + ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0); + if (ret) + goto out; + + btrfs_release_path(path); + ret = update_free_space_extent_count(trans, block_group, path, + new_extents); + +out: + return ret; +} + +EXPORT_FOR_TESTS +int __add_to_free_space_tree(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path, u64 start, u64 size) +{ + struct btrfs_free_space_info *info; + u32 flags; + int ret; + + if (block_group->needs_free_space) { + ret = __add_block_group_free_space(trans, block_group, path); + if (ret) + return ret; + } + + info = search_free_space_info(NULL, block_group, path, 0); + if (IS_ERR(info)) + return PTR_ERR(info); + flags = btrfs_free_space_flags(path->nodes[0], info); + btrfs_release_path(path); + + if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) { + return modify_free_space_bitmap(trans, block_group, path, + start, size, 0); + } else { + return add_free_space_extent(trans, block_group, path, start, + size); + } +} + +int add_to_free_space_tree(struct btrfs_trans_handle *trans, + u64 start, u64 size) +{ + struct btrfs_block_group *block_group; + struct btrfs_path *path; + int ret; + + if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE)) + return 0; + + path = btrfs_alloc_path(); + if (!path) { + ret = -ENOMEM; + goto out; + } + + block_group = btrfs_lookup_block_group(trans->fs_info, start); + if (!block_group) { + ASSERT(0); + ret = -ENOENT; + goto out; + } + + mutex_lock(&block_group->free_space_lock); + ret = __add_to_free_space_tree(trans, block_group, path, start, size); + mutex_unlock(&block_group->free_space_lock); + + btrfs_put_block_group(block_group); +out: + btrfs_free_path(path); + if (ret) + btrfs_abort_transaction(trans, ret); + return ret; +} + +/* + * Populate the free space tree by walking the extent tree. Operations on the + * extent tree that happen as a result of writes to the free space tree will go + * through the normal add/remove hooks. + */ +static int populate_free_space_tree(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group) +{ + struct btrfs_root *extent_root = trans->fs_info->extent_root; + struct btrfs_path *path, *path2; + struct btrfs_key key; + u64 start, end; + int ret; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + path->reada = READA_FORWARD; + + path2 = btrfs_alloc_path(); + if (!path2) { + btrfs_free_path(path); + return -ENOMEM; + } + + ret = add_new_free_space_info(trans, block_group, path2); + if (ret) + goto out; + + mutex_lock(&block_group->free_space_lock); + + /* + * Iterate through all of the extent and metadata items in this block + * group, adding the free space between them and the free space at the + * end. Note that EXTENT_ITEM and METADATA_ITEM are less than + * BLOCK_GROUP_ITEM, so an extent may precede the block group that it's + * contained in. + */ + key.objectid = block_group->start; + key.type = BTRFS_EXTENT_ITEM_KEY; + key.offset = 0; + + ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0); + if (ret < 0) + goto out_locked; + ASSERT(ret == 0); + + start = block_group->start; + end = block_group->start + block_group->length; + while (1) { + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + + if (key.type == BTRFS_EXTENT_ITEM_KEY || + key.type == BTRFS_METADATA_ITEM_KEY) { + if (key.objectid >= end) + break; + + if (start < key.objectid) { + ret = __add_to_free_space_tree(trans, + block_group, + path2, start, + key.objectid - + start); + if (ret) + goto out_locked; + } + start = key.objectid; + if (key.type == BTRFS_METADATA_ITEM_KEY) + start += trans->fs_info->nodesize; + else + start += key.offset; + } else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) { + if (key.objectid != block_group->start) + break; + } + + ret = btrfs_next_item(extent_root, path); + if (ret < 0) + goto out_locked; + if (ret) + break; + } + if (start < end) { + ret = __add_to_free_space_tree(trans, block_group, path2, + start, end - start); + if (ret) + goto out_locked; + } + + ret = 0; +out_locked: + mutex_unlock(&block_group->free_space_lock); +out: + btrfs_free_path(path2); + btrfs_free_path(path); + return ret; +} + +int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info) +{ + struct btrfs_trans_handle *trans; + struct btrfs_root *tree_root = fs_info->tree_root; + struct btrfs_root *free_space_root; + struct btrfs_block_group *block_group; + struct rb_node *node; + int ret; + + trans = btrfs_start_transaction(tree_root, 0); + if (IS_ERR(trans)) + return PTR_ERR(trans); + + set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags); + set_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags); + free_space_root = btrfs_create_tree(trans, + BTRFS_FREE_SPACE_TREE_OBJECTID); + if (IS_ERR(free_space_root)) { + ret = PTR_ERR(free_space_root); + goto abort; + } + fs_info->free_space_root = free_space_root; + + node = rb_first(&fs_info->block_group_cache_tree); + while (node) { + block_group = rb_entry(node, struct btrfs_block_group, + cache_node); + ret = populate_free_space_tree(trans, block_group); + if (ret) + goto abort; + node = rb_next(node); + } + + btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE); + btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID); + clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags); + ret = btrfs_commit_transaction(trans); + + /* + * Now that we've committed the transaction any reading of our commit + * root will be safe, so we can cache from the free space tree now. + */ + clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags); + return ret; + +abort: + clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags); + clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags); + btrfs_abort_transaction(trans, ret); + btrfs_end_transaction(trans); + return ret; +} + +static int clear_free_space_tree(struct btrfs_trans_handle *trans, + struct btrfs_root *root) +{ + struct btrfs_path *path; + struct btrfs_key key; + int nr; + int ret; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + path->leave_spinning = 1; + + key.objectid = 0; + key.type = 0; + key.offset = 0; + + while (1) { + ret = btrfs_search_slot(trans, root, &key, path, -1, 1); + if (ret < 0) + goto out; + + nr = btrfs_header_nritems(path->nodes[0]); + if (!nr) + break; + + path->slots[0] = 0; + ret = btrfs_del_items(trans, root, path, 0, nr); + if (ret) + goto out; + + btrfs_release_path(path); + } + + ret = 0; +out: + btrfs_free_path(path); + return ret; +} + +int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info) +{ + struct btrfs_trans_handle *trans; + struct btrfs_root *tree_root = fs_info->tree_root; + struct btrfs_root *free_space_root = fs_info->free_space_root; + int ret; + + trans = btrfs_start_transaction(tree_root, 0); + if (IS_ERR(trans)) + return PTR_ERR(trans); + + btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE); + btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID); + fs_info->free_space_root = NULL; + + ret = clear_free_space_tree(trans, free_space_root); + if (ret) + goto abort; + + ret = btrfs_del_root(trans, &free_space_root->root_key); + if (ret) + goto abort; + + list_del(&free_space_root->dirty_list); + + btrfs_tree_lock(free_space_root->node); + btrfs_clean_tree_block(free_space_root->node); + btrfs_tree_unlock(free_space_root->node); + btrfs_free_tree_block(trans, free_space_root, free_space_root->node, + 0, 1); + + btrfs_put_root(free_space_root); + + return btrfs_commit_transaction(trans); + +abort: + btrfs_abort_transaction(trans, ret); + btrfs_end_transaction(trans); + return ret; +} + +static int __add_block_group_free_space(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group, + struct btrfs_path *path) +{ + int ret; + + block_group->needs_free_space = 0; + + ret = add_new_free_space_info(trans, block_group, path); + if (ret) + return ret; + + return __add_to_free_space_tree(trans, block_group, path, + block_group->start, + block_group->length); +} + +int add_block_group_free_space(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_path *path = NULL; + int ret = 0; + + if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) + return 0; + + mutex_lock(&block_group->free_space_lock); + if (!block_group->needs_free_space) + goto out; + + path = btrfs_alloc_path(); + if (!path) { + ret = -ENOMEM; + goto out; + } + + ret = __add_block_group_free_space(trans, block_group, path); + +out: + btrfs_free_path(path); + mutex_unlock(&block_group->free_space_lock); + if (ret) + btrfs_abort_transaction(trans, ret); + return ret; +} + +int remove_block_group_free_space(struct btrfs_trans_handle *trans, + struct btrfs_block_group *block_group) +{ + struct btrfs_root *root = trans->fs_info->free_space_root; + struct btrfs_path *path; + struct btrfs_key key, found_key; + struct extent_buffer *leaf; + u64 start, end; + int done = 0, nr; + int ret; + + if (!btrfs_fs_compat_ro(trans->fs_info, FREE_SPACE_TREE)) + return 0; + + if (block_group->needs_free_space) { + /* We never added this block group to the free space tree. */ + return 0; + } + + path = btrfs_alloc_path(); + if (!path) { + ret = -ENOMEM; + goto out; + } + + start = block_group->start; + end = block_group->start + block_group->length; + + key.objectid = end - 1; + key.type = (u8)-1; + key.offset = (u64)-1; + + while (!done) { + ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1); + if (ret) + goto out; + + leaf = path->nodes[0]; + nr = 0; + path->slots[0]++; + while (path->slots[0] > 0) { + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1); + + if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) { + ASSERT(found_key.objectid == block_group->start); + ASSERT(found_key.offset == block_group->length); + done = 1; + nr++; + path->slots[0]--; + break; + } else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY || + found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) { + ASSERT(found_key.objectid >= start); + ASSERT(found_key.objectid < end); + ASSERT(found_key.objectid + found_key.offset <= end); + nr++; + path->slots[0]--; + } else { + ASSERT(0); + } + } + + ret = btrfs_del_items(trans, root, path, path->slots[0], nr); + if (ret) + goto out; + btrfs_release_path(path); + } + + ret = 0; +out: + btrfs_free_path(path); + if (ret) + btrfs_abort_transaction(trans, ret); + return ret; +} + +static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl, + struct btrfs_path *path, + u32 expected_extent_count) +{ + struct btrfs_block_group *block_group; + struct btrfs_fs_info *fs_info; + struct btrfs_root *root; + struct btrfs_key key; + int prev_bit = 0, bit; + /* Initialize to silence GCC. */ + u64 extent_start = 0; + u64 end, offset; + u64 total_found = 0; + u32 extent_count = 0; + int ret; + + block_group = caching_ctl->block_group; + fs_info = block_group->fs_info; + root = fs_info->free_space_root; + + end = block_group->start + block_group->length; + + while (1) { + ret = btrfs_next_item(root, path); + if (ret < 0) + goto out; + if (ret) + break; + + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + + if (key.type == BTRFS_FREE_SPACE_INFO_KEY) + break; + + ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY); + ASSERT(key.objectid < end && key.objectid + key.offset <= end); + + caching_ctl->progress = key.objectid; + + offset = key.objectid; + while (offset < key.objectid + key.offset) { + bit = free_space_test_bit(block_group, path, offset); + if (prev_bit == 0 && bit == 1) { + extent_start = offset; + } else if (prev_bit == 1 && bit == 0) { + total_found += add_new_free_space(block_group, + extent_start, + offset); + if (total_found > CACHING_CTL_WAKE_UP) { + total_found = 0; + wake_up(&caching_ctl->wait); + } + extent_count++; + } + prev_bit = bit; + offset += fs_info->sectorsize; + } + } + if (prev_bit == 1) { + total_found += add_new_free_space(block_group, extent_start, + end); + extent_count++; + } + + if (extent_count != expected_extent_count) { + btrfs_err(fs_info, + "incorrect extent count for %llu; counted %u, expected %u", + block_group->start, extent_count, + expected_extent_count); + ASSERT(0); + ret = -EIO; + goto out; + } + + caching_ctl->progress = (u64)-1; + + ret = 0; +out: + return ret; +} + +static int load_free_space_extents(struct btrfs_caching_control *caching_ctl, + struct btrfs_path *path, + u32 expected_extent_count) +{ + struct btrfs_block_group *block_group; + struct btrfs_fs_info *fs_info; + struct btrfs_root *root; + struct btrfs_key key; + u64 end; + u64 total_found = 0; + u32 extent_count = 0; + int ret; + + block_group = caching_ctl->block_group; + fs_info = block_group->fs_info; + root = fs_info->free_space_root; + + end = block_group->start + block_group->length; + + while (1) { + ret = btrfs_next_item(root, path); + if (ret < 0) + goto out; + if (ret) + break; + + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + + if (key.type == BTRFS_FREE_SPACE_INFO_KEY) + break; + + ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY); + ASSERT(key.objectid < end && key.objectid + key.offset <= end); + + caching_ctl->progress = key.objectid; + + total_found += add_new_free_space(block_group, key.objectid, + key.objectid + key.offset); + if (total_found > CACHING_CTL_WAKE_UP) { + total_found = 0; + wake_up(&caching_ctl->wait); + } + extent_count++; + } + + if (extent_count != expected_extent_count) { + btrfs_err(fs_info, + "incorrect extent count for %llu; counted %u, expected %u", + block_group->start, extent_count, + expected_extent_count); + ASSERT(0); + ret = -EIO; + goto out; + } + + caching_ctl->progress = (u64)-1; + + ret = 0; +out: + return ret; +} + +int load_free_space_tree(struct btrfs_caching_control *caching_ctl) +{ + struct btrfs_block_group *block_group; + struct btrfs_free_space_info *info; + struct btrfs_path *path; + u32 extent_count, flags; + int ret; + + block_group = caching_ctl->block_group; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + /* + * Just like caching_thread() doesn't want to deadlock on the extent + * tree, we don't want to deadlock on the free space tree. + */ + path->skip_locking = 1; + path->search_commit_root = 1; + path->reada = READA_FORWARD; + + info = search_free_space_info(NULL, block_group, path, 0); + if (IS_ERR(info)) { + ret = PTR_ERR(info); + goto out; + } + extent_count = btrfs_free_space_extent_count(path->nodes[0], info); + flags = btrfs_free_space_flags(path->nodes[0], info); + + /* + * We left path pointing to the free space info item, so now + * load_free_space_foo can just iterate through the free space tree from + * there. + */ + if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) + ret = load_free_space_bitmaps(caching_ctl, path, extent_count); + else + ret = load_free_space_extents(caching_ctl, path, extent_count); + +out: + btrfs_free_path(path); + return ret; +} |