btrfs: fix qgroup_free_reserved_data int overflow

The reserved data counter and input parameter is a u64, but we
inadvertently accumulate it in an int. Overflowing that int results in
freeing the wrong amount of data and breaking reserve accounting.

Unfortunately, this overflow rot spreads from there, as the qgroup
release/free functions rely on returning an int to take advantage of
negative values for error codes.

Therefore, the full fix is to return the "released" or "freed" amount by
a u64 argument and to return 0 or negative error code via the return
value.

Most of the call sites simply ignore the return value, though some
of them handle the error and count the returned bytes. Change all of
them accordingly.

CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

6 files changed, 31 insertions, 25 deletions

diff --git a/fs/btrfs/delalloc-space.c b/fs/btrfs/delalloc-space.c
index 51453d4928fa..2833e8ef4c09 100644
--- a/fs/btrfs/delalloc-space.c
+++ b/fs/btrfs/delalloc-space.c
@@ -199,7 +199,7 @@ void btrfs_free_reserved_data_space(struct btrfs_inode *inode,
 	start = round_down(start, fs_info->sectorsize);
 
 	btrfs_free_reserved_data_space_noquota(fs_info, len);
-	btrfs_qgroup_free_data(inode, reserved, start, len);
+	btrfs_qgroup_free_data(inode, reserved, start, len, NULL);
 }
 
 /*
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 92419cb8508a..33587c7ac859 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3190,7 +3190,7 @@ static long btrfs_fallocate(struct file *file, int mode,
 			qgroup_reserved -= range->len;
 		} else if (qgroup_reserved > 0) {
 			btrfs_qgroup_free_data(BTRFS_I(inode), data_reserved,
-					       range->start, range->len);
+					       range->start, range->len, NULL);
 			qgroup_reserved -= range->len;
 		}
 		list_del(&range->list);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 137c4824ff91..b9a31df58744 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -688,7 +688,7 @@ out:
 	 * And at reserve time, it's always aligned to page size, so
 	 * just free one page here.
 	 */
-	btrfs_qgroup_free_data(inode, NULL, 0, PAGE_SIZE);
+	btrfs_qgroup_free_data(inode, NULL, 0, PAGE_SIZE, NULL);
 	btrfs_free_path(path);
 	btrfs_end_transaction(trans);
 	return ret;
@@ -5132,7 +5132,7 @@ static void evict_inode_truncate_pages(struct inode *inode)
 		 */
 		if (state_flags & EXTENT_DELALLOC)
 			btrfs_qgroup_free_data(BTRFS_I(inode), NULL, start,
-					       end - start + 1);
+					       end - start + 1, NULL);
 
 		clear_extent_bit(io_tree, start, end,
 				 EXTENT_CLEAR_ALL_BITS | EXTENT_DO_ACCOUNTING,
@@ -8055,7 +8055,7 @@ next:
 		 *    reserved data space.
 		 *    Since the IO will never happen for this page.
 		 */
-		btrfs_qgroup_free_data(inode, NULL, cur, range_end + 1 - cur);
+		btrfs_qgroup_free_data(inode, NULL, cur, range_end + 1 - cur, NULL);
 		if (!inode_evicting) {
 			clear_extent_bit(tree, cur, range_end, EXTENT_LOCKED |
 				 EXTENT_DELALLOC | EXTENT_UPTODATE |
@@ -9487,7 +9487,7 @@ static struct btrfs_trans_handle *insert_prealloc_file_extent(
 	struct btrfs_path *path;
 	u64 start = ins->objectid;
 	u64 len = ins->offset;
-	int qgroup_released;
+	u64 qgroup_released = 0;
 	int ret;
 
 	memset(&stack_fi, 0, sizeof(stack_fi));
@@ -9500,9 +9500,9 @@ static struct btrfs_trans_handle *insert_prealloc_file_extent(
 	btrfs_set_stack_file_extent_compression(&stack_fi, BTRFS_COMPRESS_NONE);
 	/* Encryption and other encoding is reserved and all 0 */
 
-	qgroup_released = btrfs_qgroup_release_data(inode, file_offset, len);
-	if (qgroup_released < 0)
-		return ERR_PTR(qgroup_released);
+	ret = btrfs_qgroup_release_data(inode, file_offset, len, &qgroup_released);
+	if (ret < 0)
+		return ERR_PTR(ret);
 
 	if (trans) {
 		ret = insert_reserved_file_extent(trans, inode,
@@ -10397,7 +10397,7 @@ out_delalloc_release:
 	btrfs_delalloc_release_metadata(inode, disk_num_bytes, ret < 0);
 out_qgroup_free_data:
 	if (ret < 0)
-		btrfs_qgroup_free_data(inode, data_reserved, start, num_bytes);
+		btrfs_qgroup_free_data(inode, data_reserved, start, num_bytes, NULL);
 out_free_data_space:
 	/*
 	 * If btrfs_reserve_extent() succeeded, then we already decremented
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 8620ff402de4..a82e1417c4d2 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -152,11 +152,12 @@ static struct btrfs_ordered_extent *alloc_ordered_extent(
 {
 	struct btrfs_ordered_extent *entry;
 	int ret;
+	u64 qgroup_rsv = 0;
 
 	if (flags &
 	    ((1 << BTRFS_ORDERED_NOCOW) | (1 << BTRFS_ORDERED_PREALLOC))) {
 		/* For nocow write, we can release the qgroup rsv right now */
-		ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes);
+		ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes, &qgroup_rsv);
 		if (ret < 0)
 			return ERR_PTR(ret);
 	} else {
@@ -164,7 +165,7 @@ static struct btrfs_ordered_extent *alloc_ordered_extent(
 		 * The ordered extent has reserved qgroup space, release now
 		 * and pass the reserved number for qgroup_record to free.
 		 */
-		ret = btrfs_qgroup_release_data(inode, file_offset, num_bytes);
+		ret = btrfs_qgroup_release_data(inode, file_offset, num_bytes, &qgroup_rsv);
 		if (ret < 0)
 			return ERR_PTR(ret);
 	}
@@ -182,7 +183,7 @@ static struct btrfs_ordered_extent *alloc_ordered_extent(
 	entry->inode = igrab(&inode->vfs_inode);
 	entry->compress_type = compress_type;
 	entry->truncated_len = (u64)-1;
-	entry->qgroup_rsv = ret;
+	entry->qgroup_rsv = qgroup_rsv;
 	entry->flags = flags;
 	refcount_set(&entry->refs, 1);
 	init_waitqueue_head(&entry->wait);
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index ce446d9d7f23..a953c16c7eb8 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -4057,13 +4057,14 @@ int btrfs_qgroup_reserve_data(struct btrfs_inode *inode,
 
 /* Free ranges specified by @reserved, normally in error path */
 static int qgroup_free_reserved_data(struct btrfs_inode *inode,
-			struct extent_changeset *reserved, u64 start, u64 len)
+				     struct extent_changeset *reserved,
+				     u64 start, u64 len, u64 *freed_ret)
 {
 	struct btrfs_root *root = inode->root;
 	struct ulist_node *unode;
 	struct ulist_iterator uiter;
 	struct extent_changeset changeset;
-	int freed = 0;
+	u64 freed = 0;
 	int ret;
 
 	extent_changeset_init(&changeset);
@@ -4104,7 +4105,9 @@ static int qgroup_free_reserved_data(struct btrfs_inode *inode,
 	}
 	btrfs_qgroup_free_refroot(root->fs_info, root->root_key.objectid, freed,
 				  BTRFS_QGROUP_RSV_DATA);
-	ret = freed;
+	if (freed_ret)
+		*freed_ret = freed;
+	ret = 0;
 out:
 	extent_changeset_release(&changeset);
 	return ret;
@@ -4112,7 +4115,7 @@ out:
 
 static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
 			struct extent_changeset *reserved, u64 start, u64 len,
-			int free)
+			u64 *released, int free)
 {
 	struct extent_changeset changeset;
 	int trace_op = QGROUP_RELEASE;
@@ -4128,7 +4131,7 @@ static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
 	/* In release case, we shouldn't have @reserved */
 	WARN_ON(!free && reserved);
 	if (free && reserved)
-		return qgroup_free_reserved_data(inode, reserved, start, len);
+		return qgroup_free_reserved_data(inode, reserved, start, len, released);
 	extent_changeset_init(&changeset);
 	ret = clear_record_extent_bits(&inode->io_tree, start, start + len -1,
 				       EXTENT_QGROUP_RESERVED, &changeset);
@@ -4143,7 +4146,8 @@ static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
 		btrfs_qgroup_free_refroot(inode->root->fs_info,
 				inode->root->root_key.objectid,
 				changeset.bytes_changed, BTRFS_QGROUP_RSV_DATA);
-	ret = changeset.bytes_changed;
+	if (released)
+		*released = changeset.bytes_changed;
 out:
 	extent_changeset_release(&changeset);
 	return ret;
@@ -4162,9 +4166,10 @@ out:
  * NOTE: This function may sleep for memory allocation.
  */
 int btrfs_qgroup_free_data(struct btrfs_inode *inode,
-			struct extent_changeset *reserved, u64 start, u64 len)
+			   struct extent_changeset *reserved,
+			   u64 start, u64 len, u64 *freed)
 {
-	return __btrfs_qgroup_release_data(inode, reserved, start, len, 1);
+	return __btrfs_qgroup_release_data(inode, reserved, start, len, freed, 1);
 }
 
 /*
@@ -4182,9 +4187,9 @@ int btrfs_qgroup_free_data(struct btrfs_inode *inode,
  *
  * NOTE: This function may sleep for memory allocation.
  */
-int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len)
+int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len, u64 *released)
 {
-	return __btrfs_qgroup_release_data(inode, NULL, start, len, 0);
+	return __btrfs_qgroup_release_data(inode, NULL, start, len, released, 0);
 }
 
 static void add_root_meta_rsv(struct btrfs_root *root, int num_bytes,
diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
index 855a4f978761..15b485506104 100644
--- a/fs/btrfs/qgroup.h
+++ b/fs/btrfs/qgroup.h
@@ -358,10 +358,10 @@ int btrfs_verify_qgroup_counts(struct btrfs_fs_info *fs_info, u64 qgroupid,
 /* New io_tree based accurate qgroup reserve API */
 int btrfs_qgroup_reserve_data(struct btrfs_inode *inode,
 			struct extent_changeset **reserved, u64 start, u64 len);
-int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len);
+int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len, u64 *released);
 int btrfs_qgroup_free_data(struct btrfs_inode *inode,
 			   struct extent_changeset *reserved, u64 start,
-			   u64 len);
+			   u64 len, u64 *freed);
 int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
 			      enum btrfs_qgroup_rsv_type type, bool enforce);
 int __btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,