On Thu, Jun 04, 2020 at 05:46:05PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> xfs_iflush_done() does 3 distinct operations to the inodes attached
> to the buffer. Separate these operations out into functions so that
> it is easier to modify these operations independently in future.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_inode_item.c | 154 +++++++++++++++++++++-------------------
> 1 file changed, 81 insertions(+), 73 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
> index dee7385466f83..3894d190ea5b9 100644
> --- a/fs/xfs/xfs_inode_item.c
> +++ b/fs/xfs/xfs_inode_item.c
> @@ -640,101 +640,64 @@ xfs_inode_item_destroy(
>
>
> /*
> - * This is the inode flushing I/O completion routine. It is called
> - * from interrupt level when the buffer containing the inode is
> - * flushed to disk. It is responsible for removing the inode item
> - * from the AIL if it has not been re-logged, and unlocking the inode's
> - * flush lock.
> - *
> - * To reduce AIL lock traffic as much as possible, we scan the buffer log item
> - * list for other inodes that will run this function. We remove them from the
> - * buffer list so we can process all the inode IO completions in one AIL lock
> - * traversal.
> - *
> - * Note: Now that we attach the log item to the buffer when we first log the
> - * inode in memory, we can have unflushed inodes on the buffer list here. These
> - * inodes will have a zero ili_last_fields, so skip over them here.
> + * We only want to pull the item from the AIL if it is actually there
> + * and its location in the log has not changed since we started the
> + * flush. Thus, we only bother if the inode's lsn has not changed.
> */
> void
> -xfs_iflush_done(
> - struct xfs_buf *bp)
> +xfs_iflush_ail_updates(
> + struct xfs_ail *ailp,
> + struct list_head *list)
> {
> - struct xfs_inode_log_item *iip;
> - struct xfs_log_item *lip, *n;
> - struct xfs_ail *ailp = bp->b_mount->m_ail;
> - int need_ail = 0;
> - LIST_HEAD(tmp);
> + struct xfs_log_item *lip;
> + xfs_lsn_t tail_lsn = 0;
>
> - /*
> - * Pull the attached inodes from the buffer one at a time and take the
> - * appropriate action on them.
> - */
> - list_for_each_entry_safe(lip, n, &bp->b_li_list, li_bio_list) {
> - iip = INODE_ITEM(lip);
> + /* this is an opencoded batch version of xfs_trans_ail_delete */
> + spin_lock(&ailp->ail_lock);
> + list_for_each_entry(lip, list, li_bio_list) {
> + xfs_lsn_t lsn;
>
> - if (xfs_iflags_test(iip->ili_inode, XFS_ISTALE)) {
> - xfs_iflush_abort(iip->ili_inode);
> + if (INODE_ITEM(lip)->ili_flush_lsn != lip->li_lsn) {
> + clear_bit(XFS_LI_FAILED, &lip->li_flags);
> continue;
> }
That seems like strange logic. Shouldn't we clear LI_FAILED regardless?
>
> - if (!iip->ili_last_fields)
> - continue;
> -
> - list_move_tail(&lip->li_bio_list, &tmp);
> -
> - /* Do an unlocked check for needing the AIL lock. */
> - if (iip->ili_flush_lsn == lip->li_lsn ||
> - test_bit(XFS_LI_FAILED, &lip->li_flags))
> - need_ail++;
> + lsn = xfs_ail_delete_one(ailp, lip);
> + if (!tail_lsn && lsn)
> + tail_lsn = lsn;
> }
> + xfs_ail_update_finish(ailp, tail_lsn);
> +}
>
...
> @@ -745,6 +708,51 @@ xfs_iflush_done(
> }
> }
>
> +/*
> + * Inode buffer IO completion routine. It is responsible for removing inodes
> + * attached to the buffer from the AIL if they have not been re-logged, as well
> + * as completing the flush and unlocking the inode.
> + */
> +void
> +xfs_iflush_done(
> + struct xfs_buf *bp)
> +{
> + struct xfs_log_item *lip, *n;
> + LIST_HEAD(flushed_inodes);
> + LIST_HEAD(ail_updates);
> +
> + /*
> + * Pull the attached inodes from the buffer one at a time and take the
> + * appropriate action on them.
> + */
> + list_for_each_entry_safe(lip, n, &bp->b_li_list, li_bio_list) {
> + struct xfs_inode_log_item *iip = INODE_ITEM(lip);
> +
> + if (xfs_iflags_test(iip->ili_inode, XFS_ISTALE)) {
> + xfs_iflush_abort(iip->ili_inode);
> + continue;
> + }
> + if (!iip->ili_last_fields)
> + continue;
> +
> + /* Do an unlocked check for needing the AIL lock. */
> + if (iip->ili_flush_lsn == lip->li_lsn ||
> + test_bit(XFS_LI_FAILED, &lip->li_flags))
> + list_move_tail(&lip->li_bio_list, &ail_updates);
> + else
> + list_move_tail(&lip->li_bio_list, &flushed_inodes);
Not sure I see the point of having two lists here, particularly since
this is all based on lockless logic. At the very least it's a subtle
change in AIL processing logic and I don't think that should be buried
in a refactoring patch.
Brian
> + }
> +
> + if (!list_empty(&ail_updates)) {
> + xfs_iflush_ail_updates(bp->b_mount->m_ail, &ail_updates);
> + list_splice_tail(&ail_updates, &flushed_inodes);
> + }
> +
> + xfs_iflush_finish(bp, &flushed_inodes);
> + if (!list_empty(&flushed_inodes))
> + list_splice_tail(&flushed_inodes, &bp->b_li_list);
> +}
> +
> /*
> * This is the inode flushing abort routine. It is called from xfs_iflush when
> * the filesystem is shutting down to clean up the inode state. It is
> --
> 2.26.2.761.g0e0b3e54be
>
