From: Filipe Manana <fdmanana@suse.com>
Date: Thu, 6 Feb 2025 16:22:17 +0000 (+0900)
Subject: btrfs: avoid monopolizing a core when activating a swap file
X-Git-Tag: v6.12.14~13
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=926a16e39d8672cb57d52586e16cd67094fa6fa3;p=thirdparty%2Fkernel%2Fstable.git

btrfs: avoid monopolizing a core when activating a swap file

commit 2c8507c63f5498d4ee4af404a8e44ceae4345056 upstream.

This commit re-attempts the backport of the change to the linux-6.12.y
branch. Commit 9f372e86b9bd ("btrfs: avoid monopolizing a core when
activating a swap file") on this branch was reverted.

During swap activation we iterate over the extents of a file and we can
have many thousands of them, so we can end up in a busy loop monopolizing
a core. Avoid this by doing a voluntary reschedule after processing each
extent.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 197ba9be97187..f7e7d864f4144 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -10142,6 +10142,8 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
 			ret = -EINTR;
 			goto out;
 		}
+
+		cond_resched();
 	}
 
 	if (bsi.block_len)