On Thu, Jan 23, 2020 at 09:20:01PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Refactor xfs_read_agf and xfs_alloc_read_agf to return EAGAIN if the
> caller passed TRYLOCK and we weren't able to get the lock; and change
> the callers to recognize this.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_alloc.c | 36 ++++++++++++++----------------------
> fs/xfs/libxfs/xfs_bmap.c | 11 ++++++-----
> fs/xfs/xfs_filestream.c | 11 +++++------
> 3 files changed, 25 insertions(+), 33 deletions(-)
>
>
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 34b65635ee34..d8053bc96c4d 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2502,12 +2502,11 @@ xfs_alloc_fix_freelist(
>
> if (!pag->pagf_init) {
> error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> - if (error)
> + if (error) {
> + /* Couldn't lock the AGF so skip this AG. */
> + if (error == -EAGAIN)
> + error = 0;
> goto out_no_agbp;
> - if (!pag->pagf_init) {
> - ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> - ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> - goto out_agbp_relse;
> }
> }
>
> @@ -2533,11 +2532,10 @@ xfs_alloc_fix_freelist(
> */
> if (!agbp) {
> error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);
> - if (error)
> - goto out_no_agbp;
> - if (!agbp) {
> - ASSERT(flags & XFS_ALLOC_FLAG_TRYLOCK);
> - ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING));
> + if (error) {
> + /* Couldn't lock the AGF so skip this AG. */
> + if (error == -EAGAIN)
> + error = 0;
> goto out_no_agbp;
> }
> }
> @@ -2768,11 +2766,10 @@ xfs_alloc_pagf_init(
> xfs_buf_t *bp;
> int error;
>
> - if ((error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp)))
> - return error;
> - if (bp)
> + error = xfs_alloc_read_agf(mp, tp, agno, flags, &bp);
> + if (!error)
> xfs_trans_brelse(tp, bp);
> - return 0;
> + return error;
> }
>
> /*
> @@ -2961,12 +2958,6 @@ xfs_read_agf(
> error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
> XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
> XFS_FSS_TO_BB(mp, 1), flags, bpp, &xfs_agf_buf_ops);
> - /*
> - * Callers of xfs_read_agf() currently interpret a NULL bpp as EAGAIN
> - * and need to be converted to check for EAGAIN specifically.
> - */
> - if (error == -EAGAIN)
> - return 0;
> if (error)
> return error;
>
> @@ -2992,14 +2983,15 @@ xfs_alloc_read_agf(
>
> trace_xfs_alloc_read_agf(mp, agno);
>
> + /* We don't support trylock when freeing. */
> + ASSERT((flags & (XFS_ALLOC_FLAG_FREEING | XFS_ALLOC_FLAG_TRYLOCK)) !=
> + (XFS_ALLOC_FLAG_FREEING | XFS_ALLOC_FLAG_TRYLOCK));
Does this assert really work? Shouldn't it be
ASSERT(!(flags & XFS_ALLOC_FLAG_FREEING) ||
!(flags & XFS_ALLOC_FLAG_TRYLOCK));
Otherwise looks good:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
