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Commit 41d3c605 authored by Filipe Manana's avatar Filipe Manana Committed by Greg Kroah-Hartman
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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-5.4.y
branch. Commit 3d770d44 ("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: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarKoichiro Den <koichiro.den@canonical.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ed0c0c7d

fs/btrfs/inode.c

+2 −0
Original line number Diff line number Diff line
@@ -11079,6 +11079,8 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, 
		}



		start += len;



		cond_resched();

	}



	if (bsi.block_len)