Re: [PATCH 05/11] xfs: Remove kmem_zone_alloc() wrapper

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Nov 13, 2019 at 09:28:20AM -0800, Darrick J. Wong wrote:
> On Wed, Nov 13, 2019 at 03:23:29PM +0100, Carlos Maiolino wrote:
> > Use kmem_cache_alloc() directly.
> > 
> > Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> > ---
> >  fs/xfs/kmem.c             | 21 ---------------------
> >  fs/xfs/kmem.h             |  2 --
> >  fs/xfs/libxfs/xfs_alloc.c |  3 ++-
> >  fs/xfs/libxfs/xfs_bmap.c  |  3 ++-
> >  fs/xfs/xfs_icache.c       |  2 +-
> >  fs/xfs/xfs_trace.h        |  1 -
> >  6 files changed, 5 insertions(+), 27 deletions(-)
> > 
> > diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
> > index 1da94237a8cf..2644fdaa0549 100644
> > --- a/fs/xfs/kmem.c
> > +++ b/fs/xfs/kmem.c
> > @@ -115,24 +115,3 @@ kmem_realloc(const void *old, size_t newsize, xfs_km_flags_t flags)
> >  		congestion_wait(BLK_RW_ASYNC, HZ/50);
> >  	} while (1);
> >  }
> > -
> > -void *
> > -kmem_zone_alloc(kmem_zone_t *zone, xfs_km_flags_t flags)
> > -{
> > -	int	retries = 0;
> > -	gfp_t	lflags = kmem_flags_convert(flags);
> > -	void	*ptr;
> > -
> > -	trace_kmem_zone_alloc(kmem_cache_size(zone), flags, _RET_IP_);
> > -	do {
> > -		ptr = kmem_cache_alloc(zone, lflags);
> > -		if (ptr || (flags & KM_MAYFAIL))
> 
> Heh, nobody was using KM_MAYFAIL here at all? :)
> 
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

Bah, I got the logic backwards.  Why is it ok to remove this retry
loop?

/me hands himself another cup of coffee and says to see the reply to
patch #9.

--D

> --D
> 
> > -			return ptr;
> > -		if (!(++retries % 100))
> > -			xfs_err(NULL,
> > -		"%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
> > -				current->comm, current->pid,
> > -				__func__, lflags);
> > -		congestion_wait(BLK_RW_ASYNC, HZ/50);
> > -	} while (1);
> > -}
> > diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h
> > index c12ab170c396..33523a0b5801 100644
> > --- a/fs/xfs/kmem.h
> > +++ b/fs/xfs/kmem.h
> > @@ -81,8 +81,6 @@ kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
> >  #define kmem_zone	kmem_cache
> >  #define kmem_zone_t	struct kmem_cache
> >  
> > -extern void *kmem_zone_alloc(kmem_zone_t *, xfs_km_flags_t);
> > -
> >  static inline struct page *
> >  kmem_to_page(void *addr)
> >  {
> > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> > index 675613c7bacb..42cae87bdd2d 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.c
> > +++ b/fs/xfs/libxfs/xfs_alloc.c
> > @@ -2351,7 +2351,8 @@ xfs_defer_agfl_block(
> >  	ASSERT(xfs_bmap_free_item_zone != NULL);
> >  	ASSERT(oinfo != NULL);
> >  
> > -	new = kmem_zone_alloc(xfs_bmap_free_item_zone, 0);
> > +	new = kmem_cache_alloc(xfs_bmap_free_item_zone,
> > +			       GFP_KERNEL | __GFP_NOFAIL);
> >  	new->xefi_startblock = XFS_AGB_TO_FSB(mp, agno, agbno);
> >  	new->xefi_blockcount = 1;
> >  	new->xefi_oinfo = *oinfo;
> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > index 9fbdca183465..37596e49b92e 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.c
> > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > @@ -554,7 +554,8 @@ __xfs_bmap_add_free(
> >  #endif
> >  	ASSERT(xfs_bmap_free_item_zone != NULL);
> >  
> > -	new = kmem_zone_alloc(xfs_bmap_free_item_zone, 0);
> > +	new = kmem_cache_alloc(xfs_bmap_free_item_zone,
> > +			       GFP_KERNEL | __GFP_NOFAIL);
> >  	new->xefi_startblock = bno;
> >  	new->xefi_blockcount = (xfs_extlen_t)len;
> >  	if (oinfo)
> > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> > index 950e8a51ec66..985f48e3795f 100644
> > --- a/fs/xfs/xfs_icache.c
> > +++ b/fs/xfs/xfs_icache.c
> > @@ -40,7 +40,7 @@ xfs_inode_alloc(
> >  	 * KM_MAYFAIL and return NULL here on ENOMEM. Set the
> 
> Comment needs updating.  How about:
> 
> 	/*
> 	 * If this didn't occur in transactions, we could omit
> 	 * __GFP_NOFAIL and return NULL here on ENOMEM. Set the
> 	 * code up to do this anyway.
> 	 */
> 
> Looks ok other than that, though even with the full series applied I
> still see a few mentions of KM_* flags in comments.
> 
> --D
> 
> >  	 * code up to do this anyway.
> >  	 */
> > -	ip = kmem_zone_alloc(xfs_inode_zone, 0);
> > +	ip = kmem_cache_alloc(xfs_inode_zone, GFP_KERNEL | __GFP_NOFAIL);
> >  	if (!ip)
> >  		return NULL;
> >  	if (inode_init_always(mp->m_super, VFS_I(ip))) {
> > diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> > index c13bb3655e48..192f499ccd7e 100644
> > --- a/fs/xfs/xfs_trace.h
> > +++ b/fs/xfs/xfs_trace.h
> > @@ -3571,7 +3571,6 @@ DEFINE_KMEM_EVENT(kmem_alloc);
> >  DEFINE_KMEM_EVENT(kmem_alloc_io);
> >  DEFINE_KMEM_EVENT(kmem_alloc_large);
> >  DEFINE_KMEM_EVENT(kmem_realloc);
> > -DEFINE_KMEM_EVENT(kmem_zone_alloc);
> >  
> >  #endif /* _TRACE_XFS_H */
> >  
> > -- 
> > 2.23.0
> >