Re: [PATCH 23/26] xfs: reclaim inodes from the LRU

Christoph Hellwig
2019-10-11T10:56:20Z

> +++ b/fs/xfs/xfs_icache.c
> @@ -1193,7 +1193,7 @@ xfs_reclaim_inode(
> *
> * Return the number of inodes freed.
> */
> -STATIC int
> +int
> xfs_reclaim_inodes_ag(
> struct xfs_mount *mp,
> int flags,

This looks odd. This function actually is unused now. I think you
want to fold in the patch that removes it instead of this little hack
to make the compiler happy.

> - xfs_reclaim_inodes_ag(mp, SYNC_WAIT, INT_MAX);
> + struct xfs_ireclaim_args *ra = arg;
> + struct inode *inode = container_of(item, struct inode, i_lru);
> + struct xfs_inode *ip = XFS_I(inode);

Whitespace damage, and a line > 80 chars.

> +out_ifunlock:
> + xfs_ifunlock(ip);

This error path will instantly deadlock, given that xfs_ifunlock takes
i_flags_lock through xfs_iflags_clear, and we already hold it here.

> + /*
> + * Remove the inode from the per-AG radix tree.
> + *
> + * Because radix_tree_delete won't complain even if the item was never
> + * added to the tree assert that it's been there before to catch
> + * problems with the inode life time early on.
> + */
> + pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
> + spin_lock(&pag->pag_ici_lock);
> + if (!radix_tree_delete(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ino)))
> + ASSERT(0);

Well, it "complains" by returning NULL instead of the entry. So I think
that comment could use some updates or simply be removed.

> +void
> +xfs_dispose_inodes(
> + struct list_head *freeable)
> +{
> + while (!list_empty(freeable)) {
> + struct inode *inode;
> +
> + inode = list_first_entry(freeable, struct inode, i_lru);

This could use list_first_entry_or_null in the while loop, or not.
Or list_pop_entry if we had it, but Linus hates that :)

> +xfs_reclaim_inodes(
> + struct xfs_mount *mp)
> +{
> + while (list_lru_count(&mp->m_inode_lru)) {
> + struct xfs_ireclaim_args ra;
> + long freed, to_free;
> +
> + INIT_LIST_HEAD(&ra.freeable);
> + ra.lowest_lsn = NULLCOMMITLSN;
> + to_free = list_lru_count(&mp->m_inode_lru);

Do we want a helper to initialize the xfs_ireclaim_args? That would
solve the "issue" of not initializing dirty_skipped in a few users
and make it a little easier to use.

> +
> + freed = list_lru_walk(&mp->m_inode_lru, xfs_inode_reclaim_isolate,

Line > 80 chars.

> +static inline int __xfs_iflock_nowait(struct xfs_inode *ip)
> +{
> + if (ip->i_flags & XFS_IFLOCK)
> + return false;
> + ip->i_flags |= XFS_IFLOCK;
> + return true;
> +}

I wonder if simply open coding this would be simpler, given how magic
xfs_inode_reclaim_isolate already is, and given that we really shouldn't
use this helper anywhere else.