btrfs: add missing discards when unpinning extents with -o discard
When we clear the dirty bits in btrfs_delete_unused_bgs for extents
in the empty block group, it results in btrfs_finish_extent_commit being
unable to discard the freed extents.
The block group removal patch added an alternate path to forget extents
other than btrfs_finish_extent_commit. As a result, any extents that
would be freed when the block group is removed aren't discarded. In my
test run, with a large copy of mixed sized files followed by removal, it
left nearly 2/3 of extents undiscarded.
To clean up the block groups, we add the removed block group onto a list
that will be discarded after transaction commit.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Tested-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index aac314e..19ef3f3 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3437,6 +3437,8 @@
struct btrfs_root *root, u64 group_start,
struct extent_map *em);
void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info);
+void btrfs_get_block_group_trimming(struct btrfs_block_group_cache *cache);
+void btrfs_put_block_group_trimming(struct btrfs_block_group_cache *cache);
void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
u64 btrfs_get_alloc_profile(struct btrfs_root *root, int data);
@@ -4073,6 +4075,7 @@
void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
unsigned int line, int errno, const char *fmt, ...);
+const char *btrfs_decode_error(int errno);
__cold
void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 15411ae..6b791f3 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6131,20 +6131,19 @@
struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_block_group_cache *block_group, *tmp;
+ struct list_head *deleted_bgs;
struct extent_io_tree *unpin;
u64 start;
u64 end;
int ret;
- if (trans->aborted)
- return 0;
-
if (fs_info->pinned_extents == &fs_info->freed_extents[0])
unpin = &fs_info->freed_extents[1];
else
unpin = &fs_info->freed_extents[0];
- while (1) {
+ while (!trans->aborted) {
mutex_lock(&fs_info->unused_bg_unpin_mutex);
ret = find_first_extent_bit(unpin, 0, &start, &end,
EXTENT_DIRTY, NULL);
@@ -6163,6 +6162,34 @@
cond_resched();
}
+ /*
+ * Transaction is finished. We don't need the lock anymore. We
+ * do need to clean up the block groups in case of a transaction
+ * abort.
+ */
+ deleted_bgs = &trans->transaction->deleted_bgs;
+ list_for_each_entry_safe(block_group, tmp, deleted_bgs, bg_list) {
+ u64 trimmed = 0;
+
+ ret = -EROFS;
+ if (!trans->aborted)
+ ret = btrfs_discard_extent(root,
+ block_group->key.objectid,
+ block_group->key.offset,
+ &trimmed);
+
+ list_del_init(&block_group->bg_list);
+ btrfs_put_block_group_trimming(block_group);
+ btrfs_put_block_group(block_group);
+
+ if (ret) {
+ const char *errstr = btrfs_decode_error(ret);
+ btrfs_warn(fs_info,
+ "Discard failed while removing blockgroup: errno=%d %s\n",
+ ret, errstr);
+ }
+ }
+
return 0;
}
@@ -9903,6 +9930,11 @@
* currently running transaction might finish and a new one start,
* allowing for new block groups to be created that can reuse the same
* physical device locations unless we take this special care.
+ *
+ * There may also be an implicit trim operation if the file system
+ * is mounted with -odiscard. The same protections must remain
+ * in place until the extents have been discarded completely when
+ * the transaction commit has completed.
*/
remove_em = (atomic_read(&block_group->trimming) == 0);
/*
@@ -9977,6 +10009,7 @@
spin_lock(&fs_info->unused_bgs_lock);
while (!list_empty(&fs_info->unused_bgs)) {
u64 start, end;
+ int trimming;
block_group = list_first_entry(&fs_info->unused_bgs,
struct btrfs_block_group_cache,
@@ -10076,12 +10109,39 @@
spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
+ /* DISCARD can flip during remount */
+ trimming = btrfs_test_opt(root, DISCARD);
+
+ /* Implicit trim during transaction commit. */
+ if (trimming)
+ btrfs_get_block_group_trimming(block_group);
+
/*
* Btrfs_remove_chunk will abort the transaction if things go
* horribly wrong.
*/
ret = btrfs_remove_chunk(trans, root,
block_group->key.objectid);
+
+ if (ret) {
+ if (trimming)
+ btrfs_put_block_group_trimming(block_group);
+ goto end_trans;
+ }
+
+ /*
+ * If we're not mounted with -odiscard, we can just forget
+ * about this block group. Otherwise we'll need to wait
+ * until transaction commit to do the actual discard.
+ */
+ if (trimming) {
+ WARN_ON(!list_empty(&block_group->bg_list));
+ spin_lock(&trans->transaction->deleted_bgs_lock);
+ list_move(&block_group->bg_list,
+ &trans->transaction->deleted_bgs);
+ spin_unlock(&trans->transaction->deleted_bgs_lock);
+ btrfs_get_block_group(block_group);
+ }
end_trans:
btrfs_end_transaction(trans, root);
next:
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index fb5a6b1..abe3a66 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3272,35 +3272,23 @@
return ret;
}
-int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
- u64 *trimmed, u64 start, u64 end, u64 minlen)
+void btrfs_get_block_group_trimming(struct btrfs_block_group_cache *cache)
{
- int ret;
+ atomic_inc(&cache->trimming);
+}
- *trimmed = 0;
+void btrfs_put_block_group_trimming(struct btrfs_block_group_cache *block_group)
+{
+ struct extent_map_tree *em_tree;
+ struct extent_map *em;
+ bool cleanup;
spin_lock(&block_group->lock);
- if (block_group->removed) {
- spin_unlock(&block_group->lock);
- return 0;
- }
- atomic_inc(&block_group->trimming);
+ cleanup = (atomic_dec_and_test(&block_group->trimming) &&
+ block_group->removed);
spin_unlock(&block_group->lock);
- ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
- if (ret)
- goto out;
-
- ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
-out:
- spin_lock(&block_group->lock);
- if (atomic_dec_and_test(&block_group->trimming) &&
- block_group->removed) {
- struct extent_map_tree *em_tree;
- struct extent_map *em;
-
- spin_unlock(&block_group->lock);
-
+ if (cleanup) {
lock_chunks(block_group->fs_info->chunk_root);
em_tree = &block_group->fs_info->mapping_tree.map_tree;
write_lock(&em_tree->lock);
@@ -3324,10 +3312,31 @@
* this block group have left 1 entry each one. Free them.
*/
__btrfs_remove_free_space_cache(block_group->free_space_ctl);
- } else {
- spin_unlock(&block_group->lock);
}
+}
+int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
+ u64 *trimmed, u64 start, u64 end, u64 minlen)
+{
+ int ret;
+
+ *trimmed = 0;
+
+ spin_lock(&block_group->lock);
+ if (block_group->removed) {
+ spin_unlock(&block_group->lock);
+ return 0;
+ }
+ btrfs_get_block_group_trimming(block_group);
+ spin_unlock(&block_group->lock);
+
+ ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
+ if (ret)
+ goto out;
+
+ ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
+out:
+ btrfs_put_block_group_trimming(block_group);
return ret;
}
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index a1077e0..8da24e2 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -69,7 +69,7 @@
static int btrfs_remount(struct super_block *sb, int *flags, char *data);
-static const char *btrfs_decode_error(int errno)
+const char *btrfs_decode_error(int errno)
{
char *errstr = "unknown";
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index f5021fc..44da929 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -258,6 +258,8 @@
mutex_init(&cur_trans->cache_write_mutex);
cur_trans->num_dirty_bgs = 0;
spin_lock_init(&cur_trans->dirty_bgs_lock);
+ INIT_LIST_HEAD(&cur_trans->deleted_bgs);
+ spin_lock_init(&cur_trans->deleted_bgs_lock);
list_add_tail(&cur_trans->list, &fs_info->trans_list);
extent_io_tree_init(&cur_trans->dirty_pages,
fs_info->btree_inode->i_mapping);
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index eb09c20..edc2fbc 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -74,6 +74,8 @@
*/
struct mutex cache_write_mutex;
spinlock_t dirty_bgs_lock;
+ struct list_head deleted_bgs;
+ spinlock_t deleted_bgs_lock;
struct btrfs_delayed_ref_root delayed_refs;
int aborted;
int dirty_bg_run;