Re: [PATCH 17/22] xfs: simplify xfs_dialloc_select_ag() return values

Brian Foster
2021-05-12T12:49:42Z

On Thu, May 06, 2021 at 05:20:49PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> The only caller of xfs_dialloc_select_ag() will always return
> -ENOSPC to it's caller if the agbp returned from
> xfs_dialloc_select_ag() is NULL. IOWs, failure to find a candidate
> AGI we can allocate inodes from is always an ENOSPC condition, so
> move this logic up into xfs_dialloc_select_ag() so we can simplify
> the return logic in this function.
>
> xfs_dialloc_select_ag() now only ever returns 0 with a locked
> agbp, or an error with no agbp.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

> fs/xfs/libxfs/xfs_ialloc.c | 23 ++++++++---------------
> fs/xfs/xfs_inode.c | 3 ---
> 2 files changed, 8 insertions(+), 18 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
> index 4540fbcd68a3..872591e8f5cb 100644
> --- a/fs/xfs/libxfs/xfs_ialloc.c
> +++ b/fs/xfs/libxfs/xfs_ialloc.c
> @@ -1717,7 +1717,7 @@ xfs_dialloc_roll(
> * This function will ensure that the selected AG has free inodes available to
> * allocate from. The selected AGI will be returned locked to the caller, and it
> * will allocate more free inodes if required. If no free inodes are found or
> - * can be allocated, no AGI will be returned.
> + * can be allocated, -ENOSPC be returned.
> */
> int
> xfs_dialloc_select_ag(
> @@ -1730,7 +1730,6 @@ xfs_dialloc_select_ag(
> struct xfs_buf *agbp;
> xfs_agnumber_t agno;
> int error;
> - bool noroom = false;
> xfs_agnumber_t start_agno;
> struct xfs_perag *pag;
> struct xfs_ino_geometry *igeo = M_IGEO(mp);
> @@ -1744,7 +1743,7 @@ xfs_dialloc_select_ag(
> */
> start_agno = xfs_ialloc_ag_select(*tpp, parent, mode);
> if (start_agno == NULLAGNUMBER)
> - return 0;
> + return -ENOSPC;
>
> /*
> * If we have already hit the ceiling of inode blocks then clear
> @@ -1757,7 +1756,6 @@ xfs_dialloc_select_ag(
> if (igeo->maxicount &&
> percpu_counter_read_positive(&mp->m_icount) + igeo->ialloc_inos
> > igeo->maxicount) {
> - noroom = true;
> okalloc = false;
> }
>
> @@ -1794,10 +1792,8 @@ xfs_dialloc_select_ag(
> if (error)
> break;
>
> - if (pag->pagi_freecount) {
> - xfs_perag_put(pag);
> + if (pag->pagi_freecount)
> goto found_ag;
> - }
>
> if (!okalloc)
> goto nextag_relse_buffer;
> @@ -1805,9 +1801,6 @@ xfs_dialloc_select_ag(
> error = xfs_ialloc_ag_alloc(*tpp, agbp, pag);
> if (error < 0) {
> xfs_trans_brelse(*tpp, agbp);
> -
> - if (error == -ENOSPC)
> - error = 0;
> break;
> }
>
> @@ -1818,12 +1811,11 @@ xfs_dialloc_select_ag(
> * allocate one of the new inodes.
> */
> ASSERT(pag->pagi_freecount > 0);
> - xfs_perag_put(pag);
>
> error = xfs_dialloc_roll(tpp, agbp);
> if (error) {
> xfs_buf_relse(agbp);
> - return error;
> + break;
> }
> goto found_ag;
> }
> @@ -1831,16 +1823,17 @@ xfs_dialloc_select_ag(
> nextag_relse_buffer:
> xfs_trans_brelse(*tpp, agbp);
> nextag:
> - xfs_perag_put(pag);
> if (++agno == mp->m_sb.sb_agcount)
> agno = 0;
> if (agno == start_agno)
> - return noroom ? -ENOSPC : 0;
> + break;
> + xfs_perag_put(pag);
> }
>
> xfs_perag_put(pag);
> - return error;
> + return error ? error : -ENOSPC;
> found_ag:
> + xfs_perag_put(pag);
> *IO_agbp = agbp;
> return 0;
> }
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 25910b145d70..3918c99fa95b 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -923,9 +923,6 @@ xfs_dir_ialloc(
> if (error)
> return error;
>
> - if (!agibp)
> - return -ENOSPC;
> -
> /* Allocate an inode from the selected AG */
> error = xfs_dialloc_ag(*tpp, agibp, parent_ino, &ino);
> if (error)
> --
> 2.31.1
>