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.
Signed-off-by: Li Zefan
---
fs/btrfs/free-space-cache.c | 235 ++-
1 files changed, 164 insertions(+), 71 deletions(-)
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 8c32434..89cc54e 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2575,17 +2575,57 @@ void btrfs_init_free_cluster(struct btrfs_free_cluster
*cluster)
cluster->block_group = NULL;
}
-int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
- u64 *trimmed, u64 start, u64 end, u64 minlen)
+static int do_trimming(struct btrfs_block_group_cache *block_group,
+ u64 *total_trimmed, u64 start, u64 bytes,
+ u64 reserved_start, u64 reserved_bytes)
{
- struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
- struct btrfs_free_space *entry = NULL;
+ struct btrfs_space_info *space_info = block_group->space_info;
struct btrfs_fs_info *fs_info = block_group->fs_info;
- u64 bytes = 0;
- u64 actually_trimmed;
- int ret = 0;
+ int ret;
+ int update = 0;
+ u64 trimmed = 0;
- *trimmed = 0;
+ spin_lock(&space_info->lock);
+ spin_lock(&block_group->lock);
+ if (!block_group->ro) {
+ block_group->reserved += reserved_bytes;
+ space_info->bytes_reserved += reserved_bytes;
+ update = 1;
+ }
+ spin_unlock(&block_group->lock);
+ spin_unlock(&space_info->lock);
+
+ ret = btrfs_error_discard_extent(fs_info->extent_root,
+start, bytes, &trimmed);
+ if (!ret)
+ *total_trimmed += trimmed;
+
+ btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
+
+ if (update) {
+ spin_lock(&space_info->lock);
+ spin_lock(&block_group->lock);
+ if (block_group->ro)
+ space_info->bytes_readonly += reserved_bytes;
+ block_group->reserved -= reserved_bytes;
+ space_info->bytes_reserved -= reserved_bytes;
+ spin_unlock(&space_info->lock);
+ spin_unlock(&block_group->lock);
+ }
+
+ return ret;
+}
+
+static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
+ u64 *total_trimmed, u64 start, u64 end, u64 minlen)
+{
+ struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+ struct btrfs_free_space *entry;
+ struct rb_node *node;
+ int ret;
+ u64 extent_start;
+ u64 extent_bytes;
+ u64 bytes;
while (start < end) {
spin_lock(&ctl->tree_lock);
@@ -2596,81 +2636,118 @@ int btrfs_trim_block_group(struct
btrfs_block_group_cache *block_group,
}
entry = tree_search_offset(ctl, start, 0, 1);
- if (!entry)
- entry = tree_search_offset(ctl,
- offset_to_bitmap(ctl, start),
- 1, 1);
-
- if (!entry || entry->offset >= end) {
+ if (!entry) {
spin_unlock(&ctl->tree_lock);
break;
}
- if (entry->bitmap) {
- ret = search_bitmap(ctl, entry, &start, &bytes);
- if (!ret) {
- if (start >= end) {
- spin_unlock(&ctl->tree_lock);
- break;
- }
- bytes = min(bytes, end - start);
- bitmap_clear_bits(ctl, entry, start, bytes);
- if (entry->bytes == 0)
- free_bitmap(ctl, entry);
- } else {
- start = entry->offset + BITS_PER_BITMAP *
- block_group->sectorsize;
+ /* skip bitmaps */
+ while (entry->bitmap) {
+ node = rb_next(&entry->offset_index);
+ if (!node) {
