Re: [PATCH v13 06/10] xfs: Add xfs_attr_set_deferred and xfs_attr_remove_deferred

Darrick J. Wong
2020-11-14T02:05:30Z

On Thu, Nov 12, 2020 at 06:27:38PM -0700, Allison Henderson wrote:
>
>
> On 11/10/20 1:15 PM, Darrick J. Wong wrote:
> > On Thu, Oct 22, 2020 at 11:34:31PM -0700, Allison Henderson wrote:
> > > From: Allison Collins <allison.henderson@oracle.com>
> > >
> > > These routines to set up and start a new deferred attribute operations.
> > > These functions are meant to be called by any routine needing to
> > > initiate a deferred attribute operation as opposed to the existing
> > > inline operations. New helper function xfs_attr_item_init also added.
> > >
> > > Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> > > ---
> > > fs/xfs/libxfs/xfs_attr.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
> > > fs/xfs/libxfs/xfs_attr.h | 2 ++
> > > 2 files changed, 56 insertions(+)
> > >
> > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > > index 760383c..7fe5554 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.c
> > > +++ b/fs/xfs/libxfs/xfs_attr.c
> > > @@ -25,6 +25,7 @@
> > > #include "xfs_trans_space.h"
> > > #include "xfs_trace.h"
> > > #include "xfs_attr_item.h"
> > > +#include "xfs_attr.h"
> > > /*
> > > * xfs_attr.c
> > > @@ -643,6 +644,59 @@ xfs_attr_set(
> > > goto out_unlock;
> > > }
> > > +STATIC int
> > > +xfs_attr_item_init(
> > > + struct xfs_da_args *args,
> > > + unsigned int op_flags, /* op flag (set or remove) */
> > > + struct xfs_attr_item **attr) /* new xfs_attr_item */
> > > +{
> > > +
> > > + struct xfs_attr_item *new;
> > > +
> > > + new = kmem_alloc_large(sizeof(struct xfs_attr_item), KM_NOFS);
> >
> > I don't think we need _large allocations for struct xfs_attr_item, right?
> I will try it and see, I think it should be ok, one of the new test cases
> I'm using does try to progressively add larger and larger attrs. If it
> doesnt work, I'll make a note of it though.

Ok. Note that kmem_alloc will only return heap objects from memory
that's directly addressable by the kerneli (and can't be larger than a
page), whereas kmem_alloc_large can fall back to virtually mapped
memory, which is scarce on 32-bit systems.

--D

> >
> > > + memset(new, 0, sizeof(struct xfs_attr_item));
> >
> > Use kmem_zalloc and you won't have to memset. Better yet, zalloc will
> > get you memory that's been pre-zeroed in the background.
> >
> > > + new->xattri_op_flags = op_flags;
> > > + new->xattri_dac.da_args = args;
> > > +
> > > + *attr = new;
> > > + return 0;
> > > +}
> > > +
> > > +/* Sets an attribute for an inode as a deferred operation */
> > > +int
> > > +xfs_attr_set_deferred(
> > > + struct xfs_da_args *args)
> > > +{
> > > + struct xfs_attr_item *new;
> > > + int error = 0;
> > > +
> > > + error = xfs_attr_item_init(args, XFS_ATTR_OP_FLAGS_SET, &new);
> > > + if (error)
> > > + return error;
> > > +
> > > + xfs_defer_add(args->trans, XFS_DEFER_OPS_TYPE_ATTR, &new->xattri_list);
> > > +
> > > + return 0;
> > > +}
> >
> > The changes in "xfs: enable delayed attributes" should be moved to this
> > patch so that these new functions immediately have callers.
> Sure, will merge those patches together then
>
> >
> > (Also see the reply I sent to the next patch, which will avoid weird
> > regressions if someone's bisect lands in the middle of this series...)
> >
> > --D
> >
> > > +
> > > +/* Removes an attribute for an inode as a deferred operation */
> > > +int
> > > +xfs_attr_remove_deferred(
> > > + struct xfs_da_args *args)
> > > +{
> > > +
> > > + struct xfs_attr_item *new;
> > > + int error;
> > > +
> > > + error = xfs_attr_item_init(args, XFS_ATTR_OP_FLAGS_REMOVE, &new);
> > > + if (error)
> > > + return error;
> > > +
> > > + xfs_defer_add(args->trans, XFS_DEFER_OPS_TYPE_ATTR, &new->xattri_list);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > /*========================================================================
> > > * External routines when attribute list is inside the inode
> > > *========================================================================*/
> > > diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> > > index 5b4a1ca..8a08411 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.h
> > > +++ b/fs/xfs/libxfs/xfs_attr.h
> > > @@ -307,5 +307,7 @@ bool xfs_attr_namecheck(const void *name, size_t length);
> > > void xfs_delattr_context_init(struct xfs_delattr_context *dac,
> > > struct xfs_da_args *args);
> > > int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
> > > +int xfs_attr_set_deferred(struct xfs_da_args *args);
> > > +int xfs_attr_remove_deferred(struct xfs_da_args *args);
> > > #endif /* __XFS_ATTR_H__ */
> > > --
> > > 2.7.4
> > >