[PATCH] btrfs: free pages on error on 'btrfs_uring_read_extent'

[Miquel Sabaté Solà]

In this function the 'pages' object is never freed in the hopes that is
picked up by btrfs_uring_read_finished() whenever that executes in the
future. But that's just the happy path. Along the way previous
allocations might have gone wrong, or we might not get -EIOCBQUEUED from
btrfs_encoded_read_regular_fill_pages(). In all these cases, we go to a
cleanup section that frees all memory allocated by this function without
assuming any deferred execution, and this also needs to happen for the
'pages' allocation.

Signed-off-by: Miquel Sabaté Solà <mssola@xxxxxxxxxx>
---
 fs/btrfs/ioctl.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 38d93dae71ca..b3e8a8d9b19d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4651,7 +4651,7 @@ static int btrfs_uring_read_extent(struct kiocb *iocb, struct iov_iter *iter,
 {
 	struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
 	struct extent_io_tree *io_tree = &inode->io_tree;
-	struct page **pages;
+	struct page **pages = NULL;
 	struct btrfs_uring_priv *priv = NULL;
 	unsigned long nr_pages;
 	int ret;
@@ -4709,6 +4709,11 @@ static int btrfs_uring_read_extent(struct kiocb *iocb, struct iov_iter *iter,
 	btrfs_unlock_extent(io_tree, start, lockend, &cached_state);
 	btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);
 	kfree(priv);
+	for (int i = 0; i < nr_pages; i++) {
+		if (pages[i])
+			__free_page(pages[i]);
+	}
+	kfree(pages);
 	return ret;
 }
 
-- 
2.53.0