Merge tag 'for-5.10-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "A few fixes for various warnings that accumulated over past two weeks:

   - tree-checker: add missing return values for some errors

   - lockdep fixes
      - when reading qgroup config and starting quota rescan
      - reverse order of quota ioctl lock and VFS freeze lock

   - avoid accessing potentially stale fs info during device scan,
     reported by syzbot

   - add scope NOFS protection around qgroup relation changes

   - check for running transaction before flushing qgroups

   - fix tracking of new delalloc ranges for some cases"

* tag 'for-5.10-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix lockdep splat when enabling and disabling qgroups
  btrfs: do nofs allocations when adding and removing qgroup relations
  btrfs: fix lockdep splat when reading qgroup config on mount
  btrfs: tree-checker: add missing returns after data_ref alignment checks
  btrfs: don't access possibly stale fs_info data for printing duplicate device
  btrfs: tree-checker: add missing return after error in root_item
  btrfs: qgroup: don't commit transaction when we already hold the handle
  btrfs: fix missing delalloc new bit for new delalloc ranges

7 files changed, 158 insertions, 73 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0378933d163c..0b29bdb25105 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -878,7 +878,10 @@ struct btrfs_fs_info {
 	 */
 	struct ulist *qgroup_ulist;
 
-	/* protect user change for quota operations */
+	/*
+	 * Protect user change for quota operations. If a transaction is needed,
+	 * it must be started before locking this lock.
+	 */
 	struct mutex qgroup_ioctl_lock;
 
 	/* list of dirty qgroups to be written at next commit */
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 87355a38a654..4373da7bcc0d 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -452,46 +452,6 @@ static void btrfs_drop_pages(struct page **pages, size_t num_pages)
 	}
 }
 
-static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode,
-					 const u64 start,
-					 const u64 len,
-					 struct extent_state **cached_state)
-{
-	u64 search_start = start;
-	const u64 end = start + len - 1;
-
-	while (search_start < end) {
-		const u64 search_len = end - search_start + 1;
-		struct extent_map *em;
-		u64 em_len;
-		int ret = 0;
-
-		em = btrfs_get_extent(inode, NULL, 0, search_start, search_len);
-		if (IS_ERR(em))
-			return PTR_ERR(em);
-
-		if (em->block_start != EXTENT_MAP_HOLE)
-			goto next;
-
-		em_len = em->len;
-		if (em->start < search_start)
-			em_len -= search_start - em->start;
-		if (em_len > search_len)
-			em_len = search_len;
-
-		ret = set_extent_bit(&inode->io_tree, search_start,
-				     search_start + em_len - 1,
-				     EXTENT_DELALLOC_NEW,
-				     NULL, cached_state, GFP_NOFS);
-next:
-		search_start = extent_map_end(em);
-		free_extent_map(em);
-		if (ret)
-			return ret;
-	}
-	return 0;
-}
-
 /*
  * after copy_from_user, pages need to be dirtied and we need to make
  * sure holes are created between the current EOF and the start of
@@ -528,23 +488,6 @@ int btrfs_dirty_pages(struct btrfs_inode *inode, struct page **pages,
 			 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
 			 0, 0, cached);
 
-	if (!btrfs_is_free_space_inode(inode)) {
-		if (start_pos >= isize &&
-		    !(inode->flags & BTRFS_INODE_PREALLOC)) {
-			/*
-			 * There can't be any extents following eof in this case
-			 * so just set the delalloc new bit for the range
-			 * directly.
-			 */
-			extra_bits |= EXTENT_DELALLOC_NEW;
-		} else {
-			err = btrfs_find_new_delalloc_bytes(inode, start_pos,
-							    num_bytes, cached);
-			if (err)
-				return err;
-		}
-	}
-
 	err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
 					extra_bits, cached);
 	if (err)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index da58c58ef9aa..7e8d8169779d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2253,11 +2253,69 @@ static int add_pending_csums(struct btrfs_trans_handle *trans,
 	return 0;
 }
 
+static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode,
+					 const u64 start,
+					 const u64 len,
+					 struct extent_state **cached_state)
+{
+	u64 search_start = start;
+	const u64 end = start + len - 1;
+
+	while (search_start < end) {
+		const u64 search_len = end - search_start + 1;
+		struct extent_map *em;
+		u64 em_len;
+		int ret = 0;
+
+		em = btrfs_get_extent(inode, NULL, 0, search_start, search_len);
+		if (IS_ERR(em))
+			return PTR_ERR(em);
+
+		if (em->block_start != EXTENT_MAP_HOLE)
+			goto next;
+
+		em_len = em->len;
+		if (em->start < search_start)
+			em_len -= search_start - em->start;
+		if (em_len > search_len)
+			em_len = search_len;
+
+		ret = set_extent_bit(&inode->io_tree, search_start,
+				     search_start + em_len - 1,
+				     EXTENT_DELALLOC_NEW,
+				     NULL, cached_state, GFP_NOFS);
+next:
+		search_start = extent_map_end(em);
+		free_extent_map(em);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
 int btrfs_set_extent_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
 			      unsigned int extra_bits,
 			      struct extent_state **cached_state)
 {
 	WARN_ON(PAGE_ALIGNED(end));
+
+	if (start >= i_size_read(&inode->vfs_inode) &&
+	    !(inode->flags & BTRFS_INODE_PREALLOC)) {
+		/*
+		 * There can't be any extents following eof in this case so just
+		 * set the delalloc new bit for the range directly.
+		 */
+		extra_bits |= EXTENT_DELALLOC_NEW;
+	} else {
+		int ret;
+
+		ret = btrfs_find_new_delalloc_bytes(inode, start,
+						    end + 1 - start,
+						    cached_state);
+		if (ret)
+			return ret;
+	}
+
 	return set_extent_delalloc(&inode->io_tree, start, end, extra_bits,
 				   cached_state);
 }
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 77c54749f432..87bd37b70738 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 #include <linux/btrfs.h>
+#include <linux/sched/mm.h>
 
 #include "ctree.h"
 #include "transaction.h"
@@ -497,13 +498,13 @@ next2:
 			break;
 	}
 out:
+	btrfs_free_path(path);
 	fs_info->qgroup_flags |= flags;
 	if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))
 		clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
 	else if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN &&
 		 ret >= 0)
 		ret = qgroup_rescan_init(fs_info, rescan_progress, 0);
-	btrfs_free_path(path);
 
 	if (ret < 0) {
 		ulist_free(fs_info->qgroup_ulist);
@@ -936,6 +937,7 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
 	struct btrfs_key found_key;
 	struct btrfs_qgroup *qgroup = NULL;
 	struct btrfs_trans_handle *trans = NULL;
+	struct ulist *ulist = NULL;
 	int ret = 0;
 	int slot;
 
@@ -943,8 +945,8 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
 	if (fs_info->quota_root)
 		goto out;
 
-	fs_info->qgroup_ulist = ulist_alloc(GFP_KERNEL);
-	if (!fs_info->qgroup_ulist) {
+	ulist = ulist_alloc(GFP_KERNEL);
+	if (!ulist) {
 		ret = -ENOMEM;
 		goto out;
 	}
@@ -952,6 +954,22 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
 	ret = btrfs_sysfs_add_qgroups(fs_info);
 	if (ret < 0)
 		goto out;
+
+	/*
+	 * Unlock qgroup_ioctl_lock before starting the transaction. This is to
+	 * avoid lock acquisition inversion problems (reported by lockdep) between
+	 * qgroup_ioctl_lock and the vfs freeze semaphores, acquired when we
+	 * start a transaction.
+	 * After we started the transaction lock qgroup_ioctl_lock again and
+	 * check if someone else created the quota root in the meanwhile. If so,
+	 * just return success and release the transaction handle.
+	 *
+	 * Also we don't need to worry about someone else calling
+	 * btrfs_sysfs_add_qgroups() after we unlock and getting an error because
+	 * that function returns 0 (success) when the sysfs entries already exist.
+	 */
+	mutex_unlock(&fs_info->qgroup_ioctl_lock);
+
 	/*
 	 * 1 for quota root item
 	 * 1 for BTRFS_QGROUP_STATUS item
@@ -961,12 +979,20 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
 	 * would be a lot of overkill.
 	 */
 	trans = btrfs_start_transaction(tree_root, 2);
+
+	mutex_lock(&fs_info->qgroup_ioctl_lock);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
 		trans = NULL;
 		goto out;
 	}
 
+	if (fs_info->quota_root)
+		goto out;
+
+	fs_info->qgroup_ulist = ulist;
+	ulist = NULL;
+
 	/*
 	 * initially create the quota tree
 	 */
@@ -1124,11 +1150,14 @@ out:
 	if (ret) {
 		ulist_free(fs_info->qgroup_ulist);
 		fs_info->qgroup_ulist = NULL;
-		if (trans)
-			btrfs_end_transaction(trans);
 		btrfs_sysfs_del_qgroups(fs_info);
 	}
 	mutex_unlock(&fs_info->qgroup_ioctl_lock);
+	if (ret && trans)
+		btrfs_end_transaction(trans);
+	else if (trans)
+		ret = btrfs_end_transaction(trans);
+	ulist_free(ulist);
 	return ret;
 }
 
@@ -1141,19 +1170,29 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
 	mutex_lock(&fs_info->qgroup_ioctl_lock);
 	if (!fs_info->quota_root)
 		goto out;
+	mutex_unlock(&fs_info->qgroup_ioctl_lock);
 
 	/*
 	 * 1 For the root item
 	 *
 	 * We should also reserve enough items for the quota tree deletion in
 	 * btrfs_clean_quota_tree but this is not done.
+	 *
+	 * Also, we must always start a transaction without holding the mutex
+	 * qgroup_ioctl_lock, see btrfs_quota_enable().
 	 */
 	trans = btrfs_start_transaction(fs_info->tree_root, 1);
+
+	mutex_lock(&fs_info->qgroup_ioctl_lock);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
+		trans = NULL;
 		goto out;
 	}
 
+	if (!fs_info->quota_root)
+		goto out;
+
 	clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
 	btrfs_qgroup_wait_for_completion(fs_info, false);
 	spin_lock(&fs_info->qgroup_lock);
@@ -1167,13 +1206,13 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
 	ret = btrfs_clean_quota_tree(trans, quota_root);
 	if (ret) {
 		btrfs_abort_transaction(trans, ret);
-		goto end_trans;
+		goto out;
 	}
 
 	ret = btrfs_del_root(trans, &quota_root->root_key);
 	if (ret) {
 		btrfs_abort_transaction(trans, ret);
-		goto end_trans;
+		goto out;
 	}
 
 	list_del(&quota_root->dirty_list);
@@ -1185,10 +1224,13 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
 
 	btrfs_put_root(quota_root);
 
-end_trans:
-	ret = btrfs_end_transaction(trans);
 out:
 	mutex_unlock(&fs_info->qgroup_ioctl_lock);
+	if (ret && trans)
+		btrfs_end_transaction(trans);
+	else if (trans)
+		ret = btrfs_end_transaction(trans);
+
 	return ret;
 }
 
@@ -1324,13 +1366,17 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
 	struct btrfs_qgroup *member;
 	struct btrfs_qgroup_list *list;
 	struct ulist *tmp;
+	unsigned int nofs_flag;
 	int ret = 0;
 
 	/* Check the level of src and dst first */
 	if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))
 		return -EINVAL;
 
+	/* We hold a transaction handle open, must do a NOFS allocation. */
+	nofs_flag = memalloc_nofs_save();
 	tmp = ulist_alloc(GFP_KERNEL);
+	memalloc_nofs_restore(nofs_flag);
 	if (!tmp)
 		return -ENOMEM;
 
@@ -1387,10 +1433,14 @@ static int __del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
 	struct btrfs_qgroup_list *list;
 	struct ulist *tmp;
 	bool found = false;
+	unsigned int nofs_flag;
 	int ret = 0;
 	int ret2;
 
+	/* We hold a transaction handle open, must do a NOFS allocation. */
+	nofs_flag = memalloc_nofs_save();
 	tmp = ulist_alloc(GFP_KERNEL);
+	memalloc_nofs_restore(nofs_flag);
 	if (!tmp)
 		return -ENOMEM;
 
@@ -3512,6 +3562,7 @@ static int try_flush_qgroup(struct btrfs_root *root)
 {
 	struct btrfs_trans_handle *trans;
 	int ret;
+	bool can_commit = true;
 
 	/*
 	 * We don't want to run flush again and again, so if there is a running
@@ -3523,6 +3574,20 @@ static int try_flush_qgroup(struct btrfs_root *root)
 		return 0;
 	}
 
+	/*
+	 * If current process holds a transaction, we shouldn't flush, as we
+	 * assume all space reservation happens before a transaction handle is
+	 * held.
+	 *
+	 * But there are cases like btrfs_delayed_item_reserve_metadata() where
+	 * we try to reserve space with one transction handle already held.
+	 * In that case we can't commit transaction, but at least try to end it
+	 * and hope the started data writes can free some space.
+	 */
+	if (current->journal_info &&
+	    current->journal_info != BTRFS_SEND_TRANS_STUB)
+		can_commit = false;
+
 	ret = btrfs_start_delalloc_snapshot(root);
 	if (ret < 0)
 		goto out;
@@ -3534,7 +3599,10 @@ static int try_flush_qgroup(struct btrfs_root *root)
 		goto out;
 	}
 
-	ret = btrfs_commit_transaction(trans);
+	if (can_commit)
+		ret = btrfs_commit_transaction(trans);
+	else
+		ret = btrfs_end_transaction(trans);
 out:
 	clear_bit(BTRFS_ROOT_QGROUP_FLUSHING, &root->state);
 	wake_up(&root->qgroup_flush_wait);
diff --git a/fs/btrfs/tests/inode-tests.c b/fs/btrfs/tests/inode-tests.c
index e6719f7db386..04022069761d 100644
--- a/fs/btrfs/tests/inode-tests.c
+++ b/fs/btrfs/tests/inode-tests.c
@@ -983,7 +983,8 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 	ret = clear_extent_bit(&BTRFS_I(inode)->io_tree,
 			       BTRFS_MAX_EXTENT_SIZE >> 1,
 			       (BTRFS_MAX_EXTENT_SIZE >> 1) + sectorsize - 1,
-			       EXTENT_DELALLOC | EXTENT_UPTODATE, 0, 0, NULL);
+			       EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+			       EXTENT_UPTODATE, 0, 0, NULL);
 	if (ret) {
 		test_err("clear_extent_bit returned %d", ret);
 		goto out;
@@ -1050,7 +1051,8 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 	ret = clear_extent_bit(&BTRFS_I(inode)->io_tree,
 			       BTRFS_MAX_EXTENT_SIZE + sectorsize,
 			       BTRFS_MAX_EXTENT_SIZE + 2 * sectorsize - 1,
-			       EXTENT_DELALLOC | EXTENT_UPTODATE, 0, 0, NULL);
+			       EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+			       EXTENT_UPTODATE, 0, 0, NULL);
 	if (ret) {
 		test_err("clear_extent_bit returned %d", ret);
 		goto out;
@@ -1082,7 +1084,8 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 
 	/* Empty */
 	ret = clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, (u64)-1,
-			       EXTENT_DELALLOC | EXTENT_UPTODATE, 0, 0, NULL);
+			       EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+			       EXTENT_UPTODATE, 0, 0, NULL);
 	if (ret) {
 		test_err("clear_extent_bit returned %d", ret);
 		goto out;
@@ -1097,7 +1100,8 @@ static int test_extent_accounting(u32 sectorsize, u32 nodesize)
 out:
 	if (ret)
 		clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, (u64)-1,
-				 EXTENT_DELALLOC | EXTENT_UPTODATE, 0, 0, NULL);
+				 EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
+				 EXTENT_UPTODATE, 0, 0, NULL);
 	iput(inode);
 	btrfs_free_dummy_root(root);
 	btrfs_free_dummy_fs_info(fs_info);
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 8784b74f5232..ea2bb4cb5890 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -1068,6 +1068,7 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key,
 			    "invalid root item size, have %u expect %zu or %u",
 			    btrfs_item_size_nr(leaf, slot), sizeof(ri),
 			    btrfs_legacy_root_item_size());
+		return -EUCLEAN;
 	}
 
 	/*
@@ -1423,6 +1424,7 @@ static int check_extent_data_ref(struct extent_buffer *leaf,
 	"invalid item size, have %u expect aligned to %zu for key type %u",
 			    btrfs_item_size_nr(leaf, slot),
 			    sizeof(*dref), key->type);
+		return -EUCLEAN;
 	}
 	if (!IS_ALIGNED(key->objectid, leaf->fs_info->sectorsize)) {
 		generic_err(leaf, slot,
@@ -1451,6 +1453,7 @@ static int check_extent_data_ref(struct extent_buffer *leaf,
 			extent_err(leaf, slot,
 	"invalid extent data backref offset, have %llu expect aligned to %u",
 				   offset, leaf->fs_info->sectorsize);
+			return -EUCLEAN;
 		}
 	}
 	return 0;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a6406b3b8c2b..78637665166e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -940,7 +940,13 @@ static noinline struct btrfs_device *device_list_add(const char *path,
 			if (device->bdev != path_bdev) {
 				bdput(path_bdev);
 				mutex_unlock(&fs_devices->device_list_mutex);
-				btrfs_warn_in_rcu(device->fs_info,
+				/*
+				 * device->fs_info may not be reliable here, so
+				 * pass in a NULL instead. This avoids a
+				 * possible use-after-free when the fs_info and
+				 * fs_info->sb are already torn down.
+				 */
+				btrfs_warn_in_rcu(NULL,
 	"duplicate device %s devid %llu generation %llu scanned by %s (%d)",
 						  path, devid, found_transid,
 						  current->comm,