Re: [PATCH 23/24] xfs: factor xfs_iflush_done

Darrick J. Wong
2020-05-23T00:23:34Z

On Fri, May 22, 2020 at 01:50:28PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> 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@redhat.com>

Seems like a fairly simple refactoring,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> fs/xfs/xfs_inode_item.c | 156 +++++++++++++++++++++-------------------
> 1 file changed, 82 insertions(+), 74 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
> index af4764f97a339..4dd4f45dcc46e 100644
> --- a/fs/xfs/xfs_inode_item.c
> +++ b/fs/xfs/xfs_inode_item.c
> @@ -662,104 +662,67 @@ 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);
> - if (!iip->ili_last_fields)
> - continue;
> + /* 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) {
> + struct xfs_inode_log_item *iip = INODE_ITEM(lip);
> + xfs_lsn_t lsn;
>
> - if (xfs_iflags_test(iip->ili_inode, XFS_ISTALE)) {
> - xfs_iflush_abort(iip->ili_inode);
> + if (iip->ili_flush_lsn != lip->li_lsn) {
> + xfs_clear_li_failed(lip);
> 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);
> +}
>
> - /*
> - * 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.
> - */
> - if (need_ail) {
> - xfs_lsn_t tail_lsn = 0;
> -
> - /* this is an opencoded batch version of xfs_trans_ail_delete */
> - spin_lock(&ailp->ail_lock);
> - list_for_each_entry(lip, &tmp, li_bio_list) {
> - iip = INODE_ITEM(lip);
> - if (iip->ili_flush_lsn == lip->li_lsn) {
> - xfs_lsn_t lsn = xfs_ail_delete_one(ailp, lip);
> - if (!tail_lsn && lsn)
> - tail_lsn = lsn;
> - } else {
> - xfs_clear_li_failed(lip);
> - }
> - }
> - xfs_ail_update_finish(ailp, tail_lsn);
> - }
> +/*
> + * Walk the list of inodes that have completed their IOs. If they are clean
> + * remove them from the list and dissociate them from the buffer. Buffers that
> + * are still dirty remain linked to the buffer and on the list. Caller must
> + * handle them appropriately.
> + */
> +void
> +xfs_iflush_finish(
> + struct xfs_buf *bp,
> + struct list_head *list)
> +{
> + struct xfs_log_item *lip, *n;
>
> - /*
> - * Clean up and unlock the flush lock now we are done. We can clear the
> - * ili_last_fields bits now that we know that the data corresponding to
> - * them is safely on disk.
> - */
> - list_for_each_entry_safe(lip, n, &tmp, li_bio_list) {
> + list_for_each_entry_safe(lip, n, list, li_bio_list) {
> + struct xfs_inode_log_item *iip = INODE_ITEM(lip);
> bool drop_buffer = false;
>
> - list_del_init(&lip->li_bio_list);
> - iip = INODE_ITEM(lip);
> -
> spin_lock(&iip->ili_lock);
> iip->ili_last_fields = 0;
> iip->ili_flush_lsn = 0;
>
> /*
> * Remove the reference to the cluster buffer if the inode is
> - * clean in memory. Drop the buffer reference once we've dropped
> - * the locks we hold. If the inode is dirty in memory, we need
> - * to put the inode item back on the buffer list for another
> - * pass through the flush machinery.
> + * clean in memory and drop the buffer reference once we've
> + * dropped the locks we hold.
> */
> ASSERT(iip->ili_item.li_buf == bp);
> if (!iip->ili_fields) {
> iip->ili_item.li_buf = NULL;
> + list_del_init(&lip->li_bio_list);
> drop_buffer = true;
> - } else {
> - list_add(&lip->li_bio_list, &bp->b_li_list);
> }
> spin_unlock(&iip->ili_lock);
> xfs_ifunlock(iip->ili_inode);
> @@ -768,6 +731,51 @@ 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 (!iip->ili_last_fields)
> + continue;
> +
> + if (xfs_iflags_test(iip->ili_inode, XFS_ISTALE)) {
> + xfs_iflush_abort(iip->ili_inode);
> + 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);
> + }
> +
> + 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
>