Btrfs: rewrite btrfs_trim_block_group()
There are various bugs in block group trimming: - It may trim from offset smaller than user-specified offset. - It may trim beyond user-specified range. - It may leak free space for extents smaller than specified minlen. - It may truncate the last trimmed extent thus leak free space. - With mixed extents+bitmaps, some extents may not be trimmed. - With mixed extents+bitmaps, some bitmaps may not be trimmed (even none will be trimmed). Even for those trimmed, not all the free space in the bitmaps will be trimmed. I rewrite btrfs_trim_block_group() and break it into two functions. One is to trim extents only, and the other is to trim bitmaps only. Before patching: # fstrim -v /mnt/ /mnt/: 1496465408 bytes were trimmed After patching: # fstrim -v /mnt/ /mnt/: 2193768448 bytes were trimmed And this matches the total free space: # btrfs fi df /mnt Data: total=3.58GB, used=1.79GB System, DUP: total=8.00MB, used=4.00KB System: total=4.00MB, used=0.00 Metadata, DUP: total=205.12MB, used=97.14MB Metadata: total=8.00MB, used=0.00 Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
This commit is contained in:
Li Zefan
parent
ec9ef7a13b
commit
7fe1e64150
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@ -2594,17 +2594,57 @@ void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
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cluster->block_group = NULL;
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}
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int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
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u64 *trimmed, u64 start, u64 end, u64 minlen)
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static int do_trimming(struct btrfs_block_group_cache *block_group,
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u64 *total_trimmed, u64 start, u64 bytes,
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u64 reserved_start, u64 reserved_bytes)
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{
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struct btrfs_space_info *space_info = block_group->space_info;
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struct btrfs_fs_info *fs_info = block_group->fs_info;
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int ret;
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int update = 0;
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u64 trimmed = 0;
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spin_lock(&space_info->lock);
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spin_lock(&block_group->lock);
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if (!block_group->ro) {
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block_group->reserved += reserved_bytes;
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space_info->bytes_reserved += reserved_bytes;
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update = 1;
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}
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spin_unlock(&block_group->lock);
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spin_unlock(&space_info->lock);
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ret = btrfs_error_discard_extent(fs_info->extent_root,
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start, bytes, &trimmed);
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if (!ret)
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*total_trimmed += trimmed;
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btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
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if (update) {
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spin_lock(&space_info->lock);
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spin_lock(&block_group->lock);
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if (block_group->ro)
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space_info->bytes_readonly += reserved_bytes;
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block_group->reserved -= reserved_bytes;
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space_info->bytes_reserved -= reserved_bytes;
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spin_unlock(&space_info->lock);
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spin_unlock(&block_group->lock);
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}
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return ret;
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}
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static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
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u64 *total_trimmed, u64 start, u64 end, u64 minlen)
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{
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struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
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struct btrfs_free_space *entry = NULL;
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struct btrfs_fs_info *fs_info = block_group->fs_info;
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u64 bytes = 0;
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u64 actually_trimmed;
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struct btrfs_free_space *entry;
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struct rb_node *node;
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int ret = 0;
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*trimmed = 0;
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u64 extent_start;
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u64 extent_bytes;
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u64 bytes;
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while (start < end) {
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spin_lock(&ctl->tree_lock);
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@ -2615,81 +2655,47 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
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}
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entry = tree_search_offset(ctl, start, 0, 1);
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if (!entry)
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entry = tree_search_offset(ctl,
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offset_to_bitmap(ctl, start),
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1, 1);
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if (!entry || entry->offset >= end) {
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if (!entry) {
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spin_unlock(&ctl->tree_lock);
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break;
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}
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if (entry->bitmap) {
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ret = search_bitmap(ctl, entry, &start, &bytes);
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if (!ret) {
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if (start >= end) {
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spin_unlock(&ctl->tree_lock);
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break;
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}
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bytes = min(bytes, end - start);
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bitmap_clear_bits(ctl, entry, start, bytes);
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if (entry->bytes == 0)
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free_bitmap(ctl, entry);
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} else {
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start = entry->offset + BITS_PER_BITMAP *
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block_group->sectorsize;
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/* skip bitmaps */
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while (entry->bitmap) {
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node = rb_next(&entry->offset_index);
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if (!node) {
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spin_unlock(&ctl->tree_lock);
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ret = 0;
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continue;
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goto out;
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}
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} else {
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start = entry->offset;
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bytes = min(entry->bytes, end - start);
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unlink_free_space(ctl, entry);
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kmem_cache_free(btrfs_free_space_cachep, entry);
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entry = rb_entry(node, struct btrfs_free_space,
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offset_index);
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}
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if (entry->offset >= end) {
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spin_unlock(&ctl->tree_lock);
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break;
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}
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extent_start = entry->offset;
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extent_bytes = entry->bytes;
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start = max(start, extent_start);
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bytes = min(extent_start + extent_bytes, end) - start;
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if (bytes < minlen) {
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spin_unlock(&ctl->tree_lock);
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goto next;
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}
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unlink_free_space(ctl, entry);
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kmem_cache_free(btrfs_free_space_cachep, entry);
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spin_unlock(&ctl->tree_lock);
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if (bytes >= minlen) {
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struct btrfs_space_info *space_info;
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int update = 0;
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space_info = block_group->space_info;
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spin_lock(&space_info->lock);
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spin_lock(&block_group->lock);
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if (!block_group->ro) {
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block_group->reserved += bytes;
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space_info->bytes_reserved += bytes;
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update = 1;
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}
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spin_unlock(&block_group->lock);
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spin_unlock(&space_info->lock);
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ret = btrfs_error_discard_extent(fs_info->extent_root,
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start,
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bytes,
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&actually_trimmed);
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btrfs_add_free_space(block_group, start, bytes);
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if (update) {
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spin_lock(&space_info->lock);
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spin_lock(&block_group->lock);
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if (block_group->ro)
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space_info->bytes_readonly += bytes;
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block_group->reserved -= bytes;
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space_info->bytes_reserved -= bytes;
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spin_unlock(&space_info->lock);
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spin_unlock(&block_group->lock);
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}
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if (ret)
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break;
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*trimmed += actually_trimmed;
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}
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ret = do_trimming(block_group, total_trimmed, start, bytes,
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extent_start, extent_bytes);
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if (ret)
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break;
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next:
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start += bytes;
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bytes = 0;
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if (fatal_signal_pending(current)) {
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ret = -ERESTARTSYS;
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@ -2698,6 +2704,93 @@ int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
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cond_resched();
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}
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out:
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return ret;
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}
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static int trim_bitmaps(struct btrfs_block_group_cache *block_group,
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u64 *total_trimmed, u64 start, u64 end, u64 minlen)
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{
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struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
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struct btrfs_free_space *entry;
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int ret = 0;
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int ret2;
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u64 bytes;
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u64 offset = offset_to_bitmap(ctl, start);
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while (offset < end) {
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bool next_bitmap = false;
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spin_lock(&ctl->tree_lock);
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if (ctl->free_space < minlen) {
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spin_unlock(&ctl->tree_lock);
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break;
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}
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entry = tree_search_offset(ctl, offset, 1, 0);
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if (!entry) {
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spin_unlock(&ctl->tree_lock);
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next_bitmap = true;
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goto next;
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}
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bytes = minlen;
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ret2 = search_bitmap(ctl, entry, &start, &bytes);
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if (ret2 || start >= end) {
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spin_unlock(&ctl->tree_lock);
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next_bitmap = true;
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goto next;
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}
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bytes = min(bytes, end - start);
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if (bytes < minlen) {
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spin_unlock(&ctl->tree_lock);
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goto next;
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}
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bitmap_clear_bits(ctl, entry, start, bytes);
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if (entry->bytes == 0)
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free_bitmap(ctl, entry);
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spin_unlock(&ctl->tree_lock);
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ret = do_trimming(block_group, total_trimmed, start, bytes,
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start, bytes);
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if (ret)
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break;
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next:
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if (next_bitmap) {
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offset += BITS_PER_BITMAP * ctl->unit;
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} else {
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start += bytes;
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if (start >= offset + BITS_PER_BITMAP * ctl->unit)
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offset += BITS_PER_BITMAP * ctl->unit;
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}
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if (fatal_signal_pending(current)) {
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ret = -ERESTARTSYS;
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break;
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}
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cond_resched();
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}
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return ret;
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}
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int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
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u64 *trimmed, u64 start, u64 end, u64 minlen)
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{
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int ret;
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*trimmed = 0;
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ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
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if (ret)
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return ret;
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ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
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return ret;
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}
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