From: Filipe Manana <fdmanana@suse.com>
Date: Mon, 9 Dec 2024 16:43:44 +0000 (+0000)
Subject: btrfs: avoid monopolizing a core when activating a swap file
X-Git-Tag: v6.1.123~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bb8e287f596b62fac18ed84cc03a9f1752f6b3b8;p=thirdparty%2Fkernel%2Fstable.git

btrfs: avoid monopolizing a core when activating a swap file

commit 2c8507c63f5498d4ee4af404a8e44ceae4345056 upstream.

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index eb5f03c3336cf..16789490078ff 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7387,6 +7387,8 @@ noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
 			ret = -EAGAIN;
 			goto out;
 		}
+
+		cond_resched();
 	}
 
 	if (orig_start)