On Mon, May 31, 2021 at 03:41:07PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Disentangle the dqrele_all inode grab code from the "generic" inode walk
> grabbing code, and and use the opportunity to document why the dqrele
> grab function does what it does.
>
> Since dqrele_all is the only user of XFS_ICI_NO_TAG, rename it to
> something more specific for what we're doing.
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_icache.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++---
> fs/xfs/xfs_icache.h | 4 ++-
> 2 files changed, 62 insertions(+), 6 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 34b8b5fbd60d..5501318b5db0 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -26,6 +26,8 @@
>
> #include <linux/iversion.h>
>
> +static bool xfs_dqrele_inode_grab(struct xfs_inode *ip);
> +
Just mov the function higher up in the file rather than add forward
declarations....
> /*
> * Allocate and initialise an xfs_inode.
> */
> @@ -765,6 +767,22 @@ xfs_inode_walk_ag_grab(
> return false;
> }
>
> +static inline bool
> +xfs_grabbed_for_walk(
> + int tag,
> + struct xfs_inode *ip,
> + int iter_flags)
> +{
> + switch (tag) {
> + case XFS_ICI_BLOCKGC_TAG:
> + return xfs_inode_walk_ag_grab(ip, iter_flags);
> + case XFS_ICI_DQRELE_NONTAG:
> + return xfs_dqrele_inode_grab(ip);
> + default:
> + return false;
> + }
> +}
Not really a fan of this XFS_ICI_DQRELE_NONTAG rename. It kinda
smears caller context across the walk API. We really have two
different things here - we want a tagless lookup, and we want a
dquot specific grab function.
This API change just means we're going to have to rename the "no
tag" lookup yet again when we need some other non tag-based lookup.
And I think this is redundant, because....
> +/* Decide if we want to grab this inode to drop its dquots. */
> +static bool
> +xfs_dqrele_inode_grab(
> + struct xfs_inode *ip)
> +{
> + bool ret = false;
> +
> + ASSERT(rcu_read_lock_held());
> +
> + /* Check for stale RCU freed inode */
> + spin_lock(&ip->i_flags_lock);
> + if (!ip->i_ino)
> + goto out_unlock;
> +
> + /*
> + * Skip inodes that are anywhere in the reclaim machinery because we
> + * drop dquots before tagging an inode for reclamation.
> + */
> + if (ip->i_flags & (XFS_IRECLAIM | XFS_IRECLAIMABLE))
> + goto out_unlock;
> +
> + /*
> + * The inode looks alive; try to grab a VFS reference so that it won't
> + * get destroyed. If we got the reference, return true to say that
> + * we grabbed the inode.
> + *
> + * If we can't get the reference, then we know the inode had its VFS
> + * state torn down and hasn't yet entered the reclaim machinery. Since
> + * we also know that dquots are detached from an inode before it enters
> + * reclaim, we can skip the inode.
> + */
> + ret = igrab(VFS_I(ip)) != NULL;
> +
> +out_unlock:
> + spin_unlock(&ip->i_flags_lock);
> + return ret;
> +}
This is basically just duplication of xfs_inode_walk_ag_grab()
without the XFS_INODE_WALK_INEW_WAIT check in it. At this point I
just don't see a reason for this function or the
XFS_ICI_DQRELE_NONTAG rename just to use this grab function...
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
