Re: [PATCH v10 6/7] nfs/localio: add tracepoints for misaligned DIO READ and WRITE support

[Mike Snitzer <snitzer@kernel.org>]

On Thu, Sep 18, 2025 at 01:33:30PM -0400, Anna Schumaker wrote:
> Hi Mike,
> 
> On 9/17/25 2:18 PM, Mike Snitzer wrote:
> > Add nfs_local_dio_class and use it to create nfs_local_dio_read,
> > nfs_local_dio_write and nfs_local_dio_misaligned trace events.
> > 
> > These trace events show how NFS LOCALIO splits a given misaligned
> > IO into a mix of misaligned head and/or tail extents and a DIO-aligned
> > middle extent.  The misaligned head and/or tail extents are issued
> > using buffered IO and the DIO-aligned middle is issued using O_DIRECT.
> > 
> > This combination of trace events is useful for LOCALIO DIO READs:
> > 
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_local_dio_read/enable
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_local_dio_misaligned/enable
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_initiate_read/enable
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_readpage_done/enable
> >   echo 1 > /sys/kernel/tracing/events/xfs/xfs_file_direct_read/enable
> > 
> > This combination of trace events is useful for LOCALIO DIO WRITEs:
> > 
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_local_dio_write/enable
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_local_dio_misaligned/enable
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_initiate_write/enable
> >   echo 1 > /sys/kernel/tracing/events/nfs/nfs_writeback_done/enable
> >   echo 1 > /sys/kernel/tracing/events/xfs/xfs_file_direct_write/enable
> 
> I'm having a lot of trouble compiling this patch. I'm seeing errors like this:
> 
> 
> fs/nfs/nfstrace.h:1800:1: error: declaration of 'struct nfs_local_dio' will not be visible outside of this function [-Werror,-Wvisibility]
>  1800 | DEFINE_NFS_LOCAL_DIO_EVENT(write);
>       | ^
> fs/nfs/nfstrace.h:1796:17: note: expanded from macro 'DEFINE_NFS_LOCAL_DIO_EVENT'
>  1796 |                  const struct nfs_local_dio *local_dio),\
>       |                               ^
> fs/nfs/nfstrace.h:1800:1: error: declaration of 'struct nfs_local_dio' will not be visible outside of this function [-Werror,-Wvisibility]
> fs/nfs/nfstrace.h:1796:17: note: expanded from macro 'DEFINE_NFS_LOCAL_DIO_EVENT'
>  1796 |                  const struct nfs_local_dio *local_dio),\
>       |                               ^
> fs/nfs/nfstrace.h:1800:1: error: declaration of 'struct nfs_local_dio' will not be visible outside of this function [-Werror,-Wvisibility]
> fs/nfs/nfstrace.h:1796:17: note: expanded from macro 'DEFINE_NFS_LOCAL_DIO_EVENT'
>  1796 |                  const struct nfs_local_dio *local_dio),\
>       |                               ^
> fs/nfs/nfstrace.h:1800:1: error: declaration of 'struct nfs_local_dio' will not be visible outside of this function [-Werror,-Wvisibility]
> fs/nfs/nfstrace.h:1796:17: note: expanded from macro 'DEFINE_NFS_LOCAL_DIO_EVENT'
>  1796 |                  const struct nfs_local_dio *local_dio),\
>       |                               ^
> fs/nfs/nfstrace.h:1800:1: error: declaration of 'struct nfs_local_dio' will not be visible outside of this function [-Werror,-Wvisibility]
> fs/nfs/nfstrace.h:1796:17: note: expanded from macro 'DEFINE_NFS_LOCAL_DIO_EVENT'
>  1796 |                  const struct nfs_local_dio *local_dio),\
>       |                               ^
> fs/nfs/nfstrace.h:1800:1: error: declaration of 'struct nfs_local_dio' will not be visible outside of this function [-Werror,-Wvisibility]
> fs/nfs/nfstrace.h:1796:17: note: expanded from macro 'DEFINE_NFS_LOCAL_DIO_EVENT'
>  1796 |                  const struct nfs_local_dio *local_dio),\
>       |                               ^
> fs/nfs/nfstrace.h:1800:1: error: declaration of 'struct nfs_local_dio' will not be visible outside of this function [-Werror,-Wvisibility]
> fs/nfs/nfstrace.h:1796:17: note: expanded from macro 'DEFINE_NFS_LOCAL_DIO_EVENT'
>  1796 |                  const struct nfs_local_dio *local_dio),\
>       |                               ^
> fs/nfs/nfstrace.h:1800:1: error: incompatible pointer types passing 'const struct nfs_local_dio *' to parameter of type 'const struct nfs_local_dio *' [-Werror,-Wincompatible-pointer-types]
>  1800 | DEFINE_NFS_LOCAL_DIO_EVENT(write);
> 
> 
> Am I missing a patch somewhere along the line?
> 
> Thanks,
> Anna
> 
> > 
> > Signed-off-by: Mike Snitzer <snitzer@kernel.org>
> > ---
> >  fs/nfs/internal.h | 10 +++++++
> >  fs/nfs/localio.c  | 19 ++++++-------
> >  fs/nfs/nfs3xdr.c  |  2 +-
> >  fs/nfs/nfstrace.h | 70 +++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 89 insertions(+), 12 deletions(-)
> > 
> > diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> > index d44233cfd7949..3d380c45b5ef3 100644
> > --- a/fs/nfs/internal.h
> > +++ b/fs/nfs/internal.h
> > @@ -456,6 +456,16 @@ extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
> >  
> >  #if IS_ENABLED(CONFIG_NFS_LOCALIO)
> >  /* localio.c */
> > +struct nfs_local_dio {
> > +	u32 mem_align;
> > +	u32 offset_align;
> > +	loff_t middle_offset;
> > +	loff_t end_offset;
> > +	ssize_t	start_len;	/* Length for misaligned first extent */
> > +	ssize_t	middle_len;	/* Length for DIO-aligned middle extent */
> > +	ssize_t	end_len;	/* Length for misaligned last extent */
> > +};
> > +
> >  extern void nfs_local_probe_async(struct nfs_client *);
> >  extern void nfs_local_probe_async_work(struct work_struct *);
> >  extern struct nfsd_file *nfs_local_open_fh(struct nfs_client *,
> > diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
> > index 768af570183af..cf1533759646e 100644
> > --- a/fs/nfs/localio.c
> > +++ b/fs/nfs/localio.c
> > @@ -322,16 +322,6 @@ nfs_local_iocb_alloc(struct nfs_pgio_header *hdr,
> >  	return iocb;
> >  }
> >  
> > -struct nfs_local_dio {
> > -	u32 mem_align;
> > -	u32 offset_align;
> > -	loff_t middle_offset;
> > -	loff_t end_offset;
> > -	ssize_t	start_len;	/* Length for misaligned first extent */
> > -	ssize_t	middle_len;	/* Length for DIO-aligned middle extent */
> > -	ssize_t	end_len;	/* Length for misaligned last extent */
> > -};
> > -
> >  static bool
> >  nfs_is_local_dio_possible(struct nfs_local_kiocb *iocb, int rw,
> >  			  size_t len, struct nfs_local_dio *local_dio)
> > @@ -367,6 +357,10 @@ nfs_is_local_dio_possible(struct nfs_local_kiocb *iocb, int rw,
> >  	local_dio->middle_len = middle_end - start_end;
> >  	local_dio->end_len = orig_end - middle_end;
> >  
> > +	if (rw == ITER_DEST)
> > +		trace_nfs_local_dio_read(hdr->inode, offset, len, local_dio);
> > +	else
> > +		trace_nfs_local_dio_write(hdr->inode, offset, len, local_dio);
> >  	return true;
> >  }
> >  
> > @@ -446,8 +440,11 @@ nfs_local_iters_setup_dio(struct nfs_local_kiocb *iocb, int rw,
> >  		nfs_iov_iter_aligned_bvec(&iters[n_iters],
> >  			local_dio->mem_align-1, local_dio->offset_align-1);
> >  
> > -	if (unlikely(!iocb->iter_is_dio_aligned[n_iters]))
> > +	if (unlikely(!iocb->iter_is_dio_aligned[n_iters])) {
> > +		trace_nfs_local_dio_misaligned(iocb->hdr->inode,
> > +			iocb->hdr->args.offset, len, local_dio);
> >  		return 0; /* no DIO-aligned IO possible */
> > +	}
> >  	++n_iters;
> >  
> >  	iocb->n_iters = n_iters;
> > diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
> > index 4ae01c10b7e28..e17d729084125 100644
> > --- a/fs/nfs/nfs3xdr.c
> > +++ b/fs/nfs/nfs3xdr.c
> > @@ -23,8 +23,8 @@
> >  #include <linux/nfsacl.h>
> >  #include <linux/nfs_common.h>
> >  
> > -#include "nfstrace.h"
> >  #include "internal.h"
> > +#include "nfstrace.h"
> >  
> >  #define NFSDBG_FACILITY		NFSDBG_XDR
> >  

This change ^ was critical for fixing unknown type issues for 'struct
nfs_local_dio' issues on my build. But I haven't seen the issue you've
reported above. I'll try applying my changes on very latest upstream
tree.

Which tree/branch are you using for your baseline?  Also, which
version of gcc (which distro even) are you using?

(I even tried including "internal.h" directly in "nfstrace.h" but that
caused all sorts of different compiler issues). 

Thanks,
Mike