On Thu, Feb 18, 2021 at 03:14:58PM -0500, Brian Foster wrote:
> fstest xfs/167 produced a lockdep splat that complained about a
> nested transaction acquiring freeze protection during an eofblocks
> scan. Drop freeze protection around the block reclaim scan in the
> transaction allocation code to avoid this problem.
>
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
I think it seems reasonable, though I really wish that other patchset to
clean up all the "modify thread state when we start/end transactions"
had landed.
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_trans.c | 19 ++++++++++++++-----
> 1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
> index 44f72c09c203..c32c62d3b77a 100644
> --- a/fs/xfs/xfs_trans.c
> +++ b/fs/xfs/xfs_trans.c
> @@ -261,6 +261,7 @@ xfs_trans_alloc(
> {
> struct xfs_trans *tp;
> int error;
> + bool retried = false;
>
> /*
> * Allocate the handle before we do our freeze accounting and setting up
> @@ -288,19 +289,27 @@ xfs_trans_alloc(
> INIT_LIST_HEAD(&tp->t_dfops);
> tp->t_firstblock = NULLFSBLOCK;
>
> +retry:
> error = xfs_trans_reserve(tp, resp, blocks, rtextents);
> - if (error == -ENOSPC) {
> + if (error == -ENOSPC && !retried) {
> /*
> * We weren't able to reserve enough space for the transaction.
> * Flush the other speculative space allocations to free space.
> * Do not perform a synchronous scan because callers can hold
> * other locks.
> */
> + retried = true;
> + if (!(flags & XFS_TRANS_NO_WRITECOUNT))
> + sb_end_intwrite(mp->m_super);
> error = xfs_blockgc_free_space(mp, NULL);
> - if (!error)
> - error = xfs_trans_reserve(tp, resp, blocks, rtextents);
> - }
> - if (error) {
> + if (error) {
> + kmem_cache_free(xfs_trans_zone, tp);
> + return error;
> + }
> + if (!(flags & XFS_TRANS_NO_WRITECOUNT))
> + sb_start_intwrite(mp->m_super);
> + goto retry;
> + } else if (error) {
> xfs_trans_cancel(tp);
> return error;
> }
> --
> 2.26.2
>
