On Thu, May 14, 2015 at 08:41:07PM +0100, Filipe Manana wrote:
> When we clear an extent state's EXTENT_LOCKED bit with clear_extent_bits()
> through free_io_failure(), we weren't waking up any tasks waiting for the
> extent's state EXTENT_LOCKED bit, leading to an hang.
>
> So make sure clear_extent_bits() ends up waking up any waiters if the
> bit EXTENT_LOCKED is supplied by its callers.
>
> Zygo Blaxell was experiencing such hangs at inode eviction time after
> file unlinks. Thanks to him for a set of scripts to reproduce the issue.
Good catch!
Reviewed-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Thanks,
-liubo
>
> Reported-by: Zygo Blaxell <ce3g8jdj@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
> ---
> fs/btrfs/extent_io.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index c32d226..856c2e8 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -1277,7 +1277,12 @@ int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
> int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
> unsigned bits, gfp_t mask)
> {
> - return clear_extent_bit(tree, start, end, bits, 0, 0, NULL, mask);
> + int wake = 0;
> +
> + if (bits & EXTENT_LOCKED)
> + wake = 1;
> +
> + return clear_extent_bit(tree, start, end, bits, wake, 0, NULL, mask);
> }
>
> int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
> --
> 2.1.3
>
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