1 files changed, 159 insertions, 52 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 47c1ba141082..222d6aea4a8a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -315,12 +315,6 @@ get_caching_control(struct btrfs_block_group_cache *cache)
 	struct btrfs_caching_control *ctl;
 
 	spin_lock(&cache->lock);
-	if (cache->cached != BTRFS_CACHE_STARTED) {
-		spin_unlock(&cache->lock);
-		return NULL;
-	}
-
-	/* We're loading it the fast way, so we don't have a caching_ctl. */
 	if (!cache->caching_ctl) {
 		spin_unlock(&cache->lock);
 		return NULL;
@@ -594,6 +588,7 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
 	spin_unlock(&cache->lock);
 
 	if (fs_info->mount_opt & BTRFS_MOUNT_SPACE_CACHE) {
+		mutex_lock(&caching_ctl->mutex);
 		ret = load_free_space_cache(fs_info, cache);
 
 		spin_lock(&cache->lock);
@@ -601,15 +596,19 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
 			cache->caching_ctl = NULL;
 			cache->cached = BTRFS_CACHE_FINISHED;
 			cache->last_byte_to_unpin = (u64)-1;
+			caching_ctl->progress = (u64)-1;
 		} else {
 			if (load_cache_only) {
 				cache->caching_ctl = NULL;
 				cache->cached = BTRFS_CACHE_NO;
 			} else {
 				cache->cached = BTRFS_CACHE_STARTED;
+				cache->has_caching_ctl = 1;
 			}
 		}
 		spin_unlock(&cache->lock);
+		mutex_unlock(&caching_ctl->mutex);
+
 		wake_up(&caching_ctl->wait);
 		if (ret == 1) {
 			put_caching_control(caching_ctl);
@@ -627,6 +626,7 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
 			cache->cached = BTRFS_CACHE_NO;
 		} else {
 			cache->cached = BTRFS_CACHE_STARTED;
+			cache->has_caching_ctl = 1;
 		}
 		spin_unlock(&cache->lock);
 		wake_up(&caching_ctl->wait);
@@ -3162,7 +3162,19 @@ next_block_group(struct btrfs_root *root,
 		 struct btrfs_block_group_cache *cache)
 {
 	struct rb_node *node;
+
 	spin_lock(&root->fs_info->block_group_cache_lock);
+
+	/* If our block group was removed, we need a full search. */
+	if (RB_EMPTY_NODE(&cache->cache_node)) {
+		const u64 next_bytenr = cache->key.objectid + cache->key.offset;
+
+		spin_unlock(&root->fs_info->block_group_cache_lock);
+		btrfs_put_block_group(cache);
+		cache = btrfs_lookup_first_block_group(root->fs_info,
+						       next_bytenr);
+		return cache;
+	}
 	node = rb_next(&cache->cache_node);
 	btrfs_put_block_group(cache);
 	if (node) {
@@ -3504,6 +3516,7 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
 	found->chunk_alloc = 0;
 	found->flush = 0;
 	init_waitqueue_head(&found->wait);
+	INIT_LIST_HEAD(&found->ro_bgs);
 
 	ret = kobject_init_and_add(&found->kobj, &space_info_ktype,
 				    info->space_info_kobj, "%s",
@@ -5425,7 +5438,17 @@ static int update_block_group(struct btrfs_root *root,
 			spin_unlock(&cache->space_info->lock);
 		} else {
 			old_val -= num_bytes;
+			btrfs_set_block_group_used(&cache->item, old_val);
+			cache->pinned += num_bytes;
+			cache->space_info->bytes_pinned += num_bytes;
+			cache->space_info->bytes_used -= num_bytes;
+			cache->space_info->disk_used -= num_bytes * factor;
+			spin_unlock(&cache->lock);
+			spin_unlock(&cache->space_info->lock);
 
+			set_extent_dirty(info->pinned_extents,
+					 bytenr, bytenr + num_bytes - 1,
+					 GFP_NOFS | __GFP_NOFAIL);
 			/*
 			 * No longer have used bytes in this block group, queue
 			 * it for deletion.
@@ -5439,17 +5462,6 @@ static int update_block_group(struct btrfs_root *root,
 				}
 				spin_unlock(&info->unused_bgs_lock);
 			}
-			btrfs_set_block_group_used(&cache->item, old_val);
-			cache->pinned += num_bytes;
-			cache->space_info->bytes_pinned += num_bytes;
-			cache->space_info->bytes_used -= num_bytes;
-			cache->space_info->disk_used -= num_bytes * factor;
-			spin_unlock(&cache->lock);
-			spin_unlock(&cache->space_info->lock);
-
-			set_extent_dirty(info->pinned_extents,
-					 bytenr, bytenr + num_bytes - 1,
-					 GFP_NOFS | __GFP_NOFAIL);
 		}
 		btrfs_put_block_group(cache);
 		total -= num_bytes;
@@ -8511,6 +8523,7 @@ static int set_block_group_ro(struct btrfs_block_group_cache *cache, int force)
 	    min_allocable_bytes <= sinfo->total_bytes) {
 		sinfo->bytes_readonly += num_bytes;
 		cache->ro = 1;
+		list_add_tail(&cache->ro_list, &sinfo->ro_bgs);
 		ret = 0;
 	}
 out:
@@ -8565,15 +8578,20 @@ int btrfs_force_chunk_alloc(struct btrfs_trans_handle *trans,
 
 /*
  * helper to account the unused space of all the readonly block group in the
- * list. takes mirrors into account.
+ * space_info. takes mirrors into account.
  */
-static u64 __btrfs_get_ro_block_group_free_space(struct list_head *groups_list)
+u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
 {
 	struct btrfs_block_group_cache *block_group;
 	u64 free_bytes = 0;
 	int factor;
 
-	list_for_each_entry(block_group, groups_list, list) {
+	/* It's df, we don't care if it's racey */
+	if (list_empty(&sinfo->ro_bgs))
+		return 0;
+
+	spin_lock(&sinfo->lock);
+	list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
 		spin_lock(&block_group->lock);
 
 		if (!block_group->ro) {
@@ -8594,26 +8612,6 @@ static u64 __btrfs_get_ro_block_group_free_space(struct list_head *groups_list)
 
 		spin_unlock(&block_group->lock);
 	}
-
-	return free_bytes;
-}
-
-/*
- * helper to account the unused space of all the readonly block group in the
- * space_info. takes mirrors into account.
- */
-u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
-{
-	int i;
-	u64 free_bytes = 0;
-
-	spin_lock(&sinfo->lock);
-
-	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
-		if (!list_empty(&sinfo->block_groups[i]))
-			free_bytes += __btrfs_get_ro_block_group_free_space(
-						&sinfo->block_groups[i]);
-
 	spin_unlock(&sinfo->lock);
 
 	return free_bytes;
@@ -8633,6 +8631,7 @@ void btrfs_set_block_group_rw(struct btrfs_root *root,
 		    cache->bytes_super - btrfs_block_group_used(&cache->item);
 	sinfo->bytes_readonly -= num_bytes;
 	cache->ro = 0;
+	list_del_init(&cache->ro_list);
 	spin_unlock(&cache->lock);
 	spin_unlock(&sinfo->lock);
 }
@@ -9002,7 +9001,9 @@ btrfs_create_block_group_cache(struct btrfs_root *root, u64 start, u64 size)
 	INIT_LIST_HEAD(&cache->list);
 	INIT_LIST_HEAD(&cache->cluster_list);
 	INIT_LIST_HEAD(&cache->bg_list);
+	INIT_LIST_HEAD(&cache->ro_list);
 	btrfs_init_free_space_ctl(cache);
+	atomic_set(&cache->trimming, 0);
 
 	return cache;
 }
@@ -9195,9 +9196,8 @@ void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans,
 	int ret = 0;
 
 	list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {
-		list_del_init(&block_group->bg_list);
 		if (ret)
-			continue;
+			goto next;
 
 		spin_lock(&block_group->lock);
 		memcpy(&item, &block_group->item, sizeof(item));
@@ -9212,6 +9212,8 @@ void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans,
 					       key.objectid, key.offset);
 		if (ret)
 			btrfs_abort_transaction(trans, extent_root, ret);
+next:
+		list_del_init(&block_group->bg_list);
 	}
 }
 
@@ -9304,7 +9306,8 @@ static void clear_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
 }
 
 int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
-			     struct btrfs_root *root, u64 group_start)
+			     struct btrfs_root *root, u64 group_start,
+			     struct extent_map *em)
 {
 	struct btrfs_path *path;
 	struct btrfs_block_group_cache *block_group;
@@ -9316,6 +9319,8 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 	int ret;
 	int index;
 	int factor;
+	struct btrfs_caching_control *caching_ctl = NULL;
+	bool remove_em;
 
 	root = root->fs_info->extent_root;
 
@@ -9400,6 +9405,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 	spin_lock(&root->fs_info->block_group_cache_lock);
 	rb_erase(&block_group->cache_node,
 		 &root->fs_info->block_group_cache_tree);
+	RB_CLEAR_NODE(&block_group->cache_node);
 
 	if (root->fs_info->first_logical_byte == block_group->key.objectid)
 		root->fs_info->first_logical_byte = (u64)-1;
@@ -9411,6 +9417,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 	 * are still on the list after taking the semaphore
 	 */
 	list_del_init(&block_group->list);
+	list_del_init(&block_group->ro_list);
 	if (list_empty(&block_group->space_info->block_groups[index])) {
 		kobj = block_group->space_info->block_group_kobjs[index];
 		block_group->space_info->block_group_kobjs[index] = NULL;
@@ -9422,8 +9429,32 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 		kobject_put(kobj);
 	}
 
+	if (block_group->has_caching_ctl)
+		caching_ctl = get_caching_control(block_group);
 	if (block_group->cached == BTRFS_CACHE_STARTED)
 		wait_block_group_cache_done(block_group);
+	if (block_group->has_caching_ctl) {
+		down_write(&root->fs_info->commit_root_sem);
+		if (!caching_ctl) {
+			struct btrfs_caching_control *ctl;
+
+			list_for_each_entry(ctl,
+				    &root->fs_info->caching_block_groups, list)
+				if (ctl->block_group == block_group) {
+					caching_ctl = ctl;
+					atomic_inc(&caching_ctl->count);
+					break;
+				}
+		}
+		if (caching_ctl)
+			list_del_init(&caching_ctl->list);
+		up_write(&root->fs_info->commit_root_sem);
+		if (caching_ctl) {
+			/* Once for the caching bgs list and once for us. */
+			put_caching_control(caching_ctl);
+			put_caching_control(caching_ctl);
+		}
+	}
 
 	btrfs_remove_free_space_cache(block_group);
 
@@ -9435,6 +9466,71 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 
 	memcpy(&key, &block_group->key, sizeof(key));
 
+	lock_chunks(root);
+	if (!list_empty(&em->list)) {
+		/* We're in the transaction->pending_chunks list. */
+		free_extent_map(em);
+	}
+	spin_lock(&block_group->lock);
+	block_group->removed = 1;
+	/*
+	 * At this point trimming can't start on this block group, because we
+	 * removed the block group from the tree fs_info->block_group_cache_tree
+	 * so no one can't find it anymore and even if someone already got this
+	 * block group before we removed it from the rbtree, they have already
+	 * incremented block_group->trimming - if they didn't, they won't find
+	 * any free space entries because we already removed them all when we
+	 * called btrfs_remove_free_space_cache().
+	 *
+	 * And we must not remove the extent map from the fs_info->mapping_tree
+	 * to prevent the same logical address range and physical device space
+	 * ranges from being reused for a new block group. This is because our
+	 * fs trim operation (btrfs_trim_fs() / btrfs_ioctl_fitrim()) is
+	 * completely transactionless, so while it is trimming a range the
+	 * 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.
+	 */
+	remove_em = (atomic_read(&block_group->trimming) == 0);
+	/*
+	 * Make sure a trimmer task always sees the em in the pinned_chunks list
+	 * if it sees block_group->removed == 1 (needs to lock block_group->lock
+	 * before checking block_group->removed).
+	 */
+	if (!remove_em) {
+		/*
+		 * Our em might be in trans->transaction->pending_chunks which
+		 * is protected by fs_info->chunk_mutex ([lock|unlock]_chunks),
+		 * and so is the fs_info->pinned_chunks list.
+		 *
+		 * So at this point we must be holding the chunk_mutex to avoid
+		 * any races with chunk allocation (more specifically at
+		 * volumes.c:contains_pending_extent()), to ensure it always
+		 * sees the em, either in the pending_chunks list or in the
+		 * pinned_chunks list.
+		 */
+		list_move_tail(&em->list, &root->fs_info->pinned_chunks);
+	}
+	spin_unlock(&block_group->lock);
+
+	if (remove_em) {
+		struct extent_map_tree *em_tree;
+
+		em_tree = &root->fs_info->mapping_tree.map_tree;
+		write_lock(&em_tree->lock);
+		/*
+		 * The em might be in the pending_chunks list, so make sure the
+		 * chunk mutex is locked, since remove_extent_mapping() will
+		 * delete us from that list.
+		 */
+		remove_extent_mapping(em_tree, em);
+		write_unlock(&em_tree->lock);
+		/* once for the tree */
+		free_extent_map(em);
+	}
+
+	unlock_chunks(root);
+
 	btrfs_put_block_group(block_group);
 	btrfs_put_block_group(block_group);
 
@@ -9523,10 +9619,18 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
 		 */
 		start = block_group->key.objectid;
 		end = start + block_group->key.offset - 1;
-		clear_extent_bits(&fs_info->freed_extents[0], start, end,
+		ret = clear_extent_bits(&fs_info->freed_extents[0], start, end,
 				  EXTENT_DIRTY, GFP_NOFS);
-		clear_extent_bits(&fs_info->freed_extents[1], start, end,
+		if (ret) {
+			btrfs_set_block_group_rw(root, block_group);
+			goto end_trans;
+		}
+		ret = clear_extent_bits(&fs_info->freed_extents[1], start, end,
 				  EXTENT_DIRTY, GFP_NOFS);
+		if (ret) {
+			btrfs_set_block_group_rw(root, block_group);
+			goto end_trans;
+		}
 
 		/* Reset pinned so btrfs_put_block_group doesn't complain */
 		block_group->pinned = 0;
@@ -9537,6 +9641,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
 		 */
 		ret = btrfs_remove_chunk(trans, root,
 					 block_group->key.objectid);
+end_trans:
 		btrfs_end_transaction(trans, root);
 next:
 		btrfs_put_block_group(block_group);
@@ -9657,12 +9762,14 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
 }
 
 /*
- * btrfs_{start,end}_write() is similar to mnt_{want, drop}_write(),
- * they are used to prevent the some tasks writing data into the page cache
- * by nocow before the subvolume is snapshoted, but flush the data into
- * the disk after the snapshot creation.
+ * btrfs_{start,end}_write_no_snapshoting() are similar to
+ * mnt_{want,drop}_write(), they are used to prevent some tasks from writing
+ * data into the page cache through nocow before the subvolume is snapshoted,
+ * but flush the data into disk after the snapshot creation, or to prevent
+ * operations while snapshoting is ongoing and that cause the snapshot to be
+ * inconsistent (writes followed by expanding truncates for example).
  */
-void btrfs_end_nocow_write(struct btrfs_root *root)
+void btrfs_end_write_no_snapshoting(struct btrfs_root *root)
 {
 	percpu_counter_dec(&root->subv_writers->counter);
 	/*
@@ -9674,7 +9781,7 @@ void btrfs_end_nocow_write(struct btrfs_root *root)
 		wake_up(&root->subv_writers->wait);
 }
 
-int btrfs_start_nocow_write(struct btrfs_root *root)
+int btrfs_start_write_no_snapshoting(struct btrfs_root *root)
 {
 	if (atomic_read(&root->will_be_snapshoted))
 		return 0;
@@ -9685,7 +9792,7 @@ int btrfs_start_nocow_write(struct btrfs_root *root)
 	 */
 	smp_mb();
 	if (atomic_read(&root->will_be_snapshoted)) {
-		btrfs_end_nocow_write(root);
+		btrfs_end_write_no_snapshoting(root);
 		return 0;
 	}
 	return 1;