Re: [PATCH v2 1/3] xfs: add bmapi nodiscard flag

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

On Tue, May 08, 2018 at 11:12:42AM -0700, Darrick J. Wong wrote:
> On Tue, May 08, 2018 at 01:22:29PM -0400, Brian Foster wrote:
> > Freed extents are unconditionally discarded when online discard is
> > enabled. Define XFS_BMAPI_NODISCARD to allow callers to bypass
> > discards when unnecessary. For example, this will be useful for
> > eofblocks trimming.
> > 
> > This patch does not change behavior.
> > 
> > Signed-off-by: Brian Foster <bfoster@redhat.com>
> > ---
> >  fs/xfs/libxfs/xfs_alloc.c  | 10 +++++++---
> >  fs/xfs/libxfs/xfs_alloc.h  | 27 +++++++++++++++++++++++++--
> >  fs/xfs/libxfs/xfs_bmap.c   | 17 +++++++++++++----
> >  fs/xfs/libxfs/xfs_bmap.h   | 30 ++++++++++++++++++++++++++++--
> >  fs/xfs/xfs_extfree_item.c  |  2 +-
> >  fs/xfs/xfs_trans.h         |  3 ++-
> >  fs/xfs/xfs_trans_extfree.c | 13 +++++++++----
> >  7 files changed, 85 insertions(+), 17 deletions(-)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> > index 4bcc095fe44a..06e4b0c47c01 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.c
> > +++ b/fs/xfs/libxfs/xfs_alloc.c
> > @@ -2949,18 +2949,20 @@ xfs_free_extent_fix_freelist(
> >   * after fixing up the freelist.
> >   */
> >  int				/* error */
> > -xfs_free_extent(
> > +__xfs_free_extent(
> >  	struct xfs_trans	*tp,	/* transaction pointer */
> >  	xfs_fsblock_t		bno,	/* starting block number of extent */
> >  	xfs_extlen_t		len,	/* length of extent */
> >  	struct xfs_owner_info	*oinfo,	/* extent owner */
> > -	enum xfs_ag_resv_type	type)	/* block reservation type */
> > +	enum xfs_ag_resv_type	type,	/* block reservation type */
> > +	bool			skip_discard)
> >  {
> >  	struct xfs_mount	*mp = tp->t_mountp;
> >  	struct xfs_buf		*agbp;
> >  	xfs_agnumber_t		agno = XFS_FSB_TO_AGNO(mp, bno);
> >  	xfs_agblock_t		agbno = XFS_FSB_TO_AGBNO(mp, bno);
> >  	int			error;
> > +	unsigned int		busy_flags = 0;
> >  
> >  	ASSERT(len != 0);
> >  	ASSERT(type != XFS_AG_RESV_AGFL);
> > @@ -2984,7 +2986,9 @@ xfs_free_extent(
> >  	if (error)
> >  		goto err;
> >  
> > -	xfs_extent_busy_insert(tp, agno, agbno, len, 0);
> > +	if (skip_discard)
> > +		busy_flags |= XFS_EXTENT_BUSY_SKIP_DISCARD;
> > +	xfs_extent_busy_insert(tp, agno, agbno, len, busy_flags);
> >  	return 0;
> >  
> >  err:
> > diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
> > index cbf789ea5a4e..4a8e8dcaf352 100644
> > --- a/fs/xfs/libxfs/xfs_alloc.h
> > +++ b/fs/xfs/libxfs/xfs_alloc.h
> > @@ -191,12 +191,35 @@ xfs_alloc_vextent(
> >   * Free an extent.
> >   */
> >  int				/* error */
> > -xfs_free_extent(
> > +__xfs_free_extent(
> >  	struct xfs_trans	*tp,	/* transaction pointer */
> >  	xfs_fsblock_t		bno,	/* starting block number of extent */
> >  	xfs_extlen_t		len,	/* length of extent */
> >  	struct xfs_owner_info	*oinfo,	/* extent owner */
> > -	enum xfs_ag_resv_type	type);	/* block reservation type */
> > +	enum xfs_ag_resv_type	type,	/* block reservation type */
> > +	bool			skip_discard);
> > +
> > +static inline int
> > +xfs_free_extent(
> > +	struct xfs_trans	*tp,
> > +	xfs_fsblock_t		bno,
> > +	xfs_extlen_t		len,
> > +	struct xfs_owner_info	*oinfo,
> > +	enum xfs_ag_resv_type	type)
> > +{
> > +	return __xfs_free_extent(tp, bno, len, oinfo, type, false);
> > +}
> > +
> > +static inline int
> > +xfs_free_extent_nodiscard(
> > +	struct xfs_trans	*tp,
> > +	xfs_fsblock_t		bno,
> > +	xfs_extlen_t		len,
> > +	struct xfs_owner_info	*oinfo,
> > +	enum xfs_ag_resv_type	type)
> > +{
> > +	return __xfs_free_extent(tp, bno, len, oinfo, type, true);
> > +}
> >  
> >  int				/* error */
> >  xfs_alloc_lookup_le(
> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > index 040eeda8426f..dfec27b10e7a 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.c
> > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > @@ -542,12 +542,13 @@ xfs_bmap_validate_ret(
> >   * The list is maintained sorted (by block number).
> >   */
> >  void
> > -xfs_bmap_add_free(
> > +__xfs_bmap_add_free(
> >  	struct xfs_mount		*mp,
> >  	struct xfs_defer_ops		*dfops,
> >  	xfs_fsblock_t			bno,
> >  	xfs_filblks_t			len,
> > -	struct xfs_owner_info		*oinfo)
> > +	struct xfs_owner_info		*oinfo,
> > +	bool				skip_discard)
> >  {
> >  	struct xfs_extent_free_item	*new;		/* new element */
> >  #ifdef DEBUG
> > @@ -574,6 +575,7 @@ xfs_bmap_add_free(
> >  		new->xefi_oinfo = *oinfo;
> >  	else
> >  		xfs_rmap_skip_owner_update(&new->xefi_oinfo);
> > +	new->xefi_skip_discard = skip_discard;
> >  	trace_xfs_bmap_free_defer(mp, XFS_FSB_TO_AGNO(mp, bno), 0,
> >  			XFS_FSB_TO_AGBNO(mp, bno), len);
> >  	xfs_defer_add(dfops, XFS_DEFER_OPS_TYPE_FREE, &new->xefi_list);
> > @@ -5104,9 +5106,16 @@ xfs_bmap_del_extent_real(
> >  			error = xfs_refcount_decrease_extent(mp, dfops, del);
> >  			if (error)
> >  				goto done;
> > -		} else
> > -			xfs_bmap_add_free(mp, dfops, del->br_startblock,
> > +		} else {
> > +			if (bflags & XFS_BMAPI_NODISCARD) {
> > +				xfs_bmap_add_free_nodiscard(mp, dfops,
> > +					del->br_startblock, del->br_blockcount,
> > +					NULL);
> > +			} else {
> > +				xfs_bmap_add_free(mp, dfops, del->br_startblock,
> >  					del->br_blockcount, NULL);
> > +			}
> > +		}
> >  	}
> >  
> >  	/*
> > diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> > index 2b766b37096d..d8832e049636 100644
> > --- a/fs/xfs/libxfs/xfs_bmap.h
> > +++ b/fs/xfs/libxfs/xfs_bmap.h
> > @@ -68,6 +68,7 @@ struct xfs_extent_free_item
> >  	xfs_extlen_t		xefi_blockcount;/* number of blocks in extent */
> >  	struct list_head	xefi_list;
> >  	struct xfs_owner_info	xefi_oinfo;	/* extent owner */
> > +	bool			xefi_skip_discard;
> >  };
> >  
> >  #define	XFS_BMAP_MAX_NMAP	4
> > @@ -116,6 +117,9 @@ struct xfs_extent_free_item
> >  /* Only convert unwritten extents, don't allocate new blocks */
> >  #define XFS_BMAPI_CONVERT_ONLY	0x800
> >  
> > +/* Skip online discard of freed extents */
> > +#define XFS_BMAPI_NODISCARD	0x1000
> > +
> >  #define XFS_BMAPI_FLAGS \
> >  	{ XFS_BMAPI_ENTIRE,	"ENTIRE" }, \
> >  	{ XFS_BMAPI_METADATA,	"METADATA" }, \
> 
> XFS_BMAPI_FLAGS needs to be updated ot have XFS_BMAPI_NODISCARD.

Ok, truncated thought there...

XFS_BMAPI_FLAGS needs to be updated to include a string for
XFS_BMAPI_NODISCARD.

Should I just add:

	{ XFS_BMAPI_NODISCARD,	"NODISCARD" }, \

at the end of XFS_BMAPI_FLAGS?

Granted I kinda hate these, because the C definition is emitted as a
string as part of every tracepoint definition in the xfs module and again
for every trace point definition in the ftrace binary stream, but I
guess people find the flags translation useful?  I ripped all of mine
out prior to submitting reflink/rmap/scrub...

--D

> 
> Looks ok otherwise,
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> --D
> 
> > @@ -192,9 +196,9 @@ void	xfs_trim_extent(struct xfs_bmbt_irec *irec, xfs_fileoff_t bno,
> >  void	xfs_trim_extent_eof(struct xfs_bmbt_irec *, struct xfs_inode *);
> >  int	xfs_bmap_add_attrfork(struct xfs_inode *ip, int size, int rsvd);
> >  void	xfs_bmap_local_to_extents_empty(struct xfs_inode *ip, int whichfork);
> > -void	xfs_bmap_add_free(struct xfs_mount *mp, struct xfs_defer_ops *dfops,
> > +void	__xfs_bmap_add_free(struct xfs_mount *mp, struct xfs_defer_ops *dfops,
> >  			  xfs_fsblock_t bno, xfs_filblks_t len,
> > -			  struct xfs_owner_info *oinfo);
> > +			  struct xfs_owner_info *oinfo, bool skip_discard);
> >  void	xfs_bmap_compute_maxlevels(struct xfs_mount *mp, int whichfork);
> >  int	xfs_bmap_first_unused(struct xfs_trans *tp, struct xfs_inode *ip,
> >  		xfs_extlen_t len, xfs_fileoff_t *unused, int whichfork);
> > @@ -240,6 +244,28 @@ int	xfs_bmapi_reserve_delalloc(struct xfs_inode *ip, int whichfork,
> >  		struct xfs_bmbt_irec *got, struct xfs_iext_cursor *cur,
> >  		int eof);
> >  
> > +static inline void
> > +xfs_bmap_add_free(
> > +	struct xfs_mount		*mp,
> > +	struct xfs_defer_ops		*dfops,
> > +	xfs_fsblock_t			bno,
> > +	xfs_filblks_t			len,
> > +	struct xfs_owner_info		*oinfo)
> > +{
> > +	__xfs_bmap_add_free(mp, dfops, bno, len, oinfo, false);
> > +}
> > +
> > +static inline void
> > +xfs_bmap_add_free_nodiscard(
> > +	struct xfs_mount		*mp,
> > +	struct xfs_defer_ops		*dfops,
> > +	xfs_fsblock_t			bno,
> > +	xfs_filblks_t			len,
> > +	struct xfs_owner_info		*oinfo)
> > +{
> > +	__xfs_bmap_add_free(mp, dfops, bno, len, oinfo, true);
> > +}
> > +
> >  enum xfs_bmap_intent_type {
> >  	XFS_BMAP_MAP = 1,
> >  	XFS_BMAP_UNMAP,
> > diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
> > index b5b1e567b9f4..4735a31793b0 100644
> > --- a/fs/xfs/xfs_extfree_item.c
> > +++ b/fs/xfs/xfs_extfree_item.c
> > @@ -542,7 +542,7 @@ xfs_efi_recover(
> >  	for (i = 0; i < efip->efi_format.efi_nextents; i++) {
> >  		extp = &efip->efi_format.efi_extents[i];
> >  		error = xfs_trans_free_extent(tp, efdp, extp->ext_start,
> > -					      extp->ext_len, &oinfo);
> > +					      extp->ext_len, &oinfo, false);
> >  		if (error)
> >  			goto abort_error;
> >  
> > diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
> > index 9d542dfe0052..d5be3f6a3e8f 100644
> > --- a/fs/xfs/xfs_trans.h
> > +++ b/fs/xfs/xfs_trans.h
> > @@ -228,7 +228,8 @@ struct xfs_efd_log_item	*xfs_trans_get_efd(struct xfs_trans *,
> >  				  uint);
> >  int		xfs_trans_free_extent(struct xfs_trans *,
> >  				      struct xfs_efd_log_item *, xfs_fsblock_t,
> > -				      xfs_extlen_t, struct xfs_owner_info *);
> > +				      xfs_extlen_t, struct xfs_owner_info *,
> > +				      bool);
> >  int		xfs_trans_commit(struct xfs_trans *);
> >  int		xfs_trans_roll(struct xfs_trans **);
> >  int		xfs_trans_roll_inode(struct xfs_trans **, struct xfs_inode *);
> > diff --git a/fs/xfs/xfs_trans_extfree.c b/fs/xfs/xfs_trans_extfree.c
> > index ab438647592a..dab8b3b7a9b8 100644
> > --- a/fs/xfs/xfs_trans_extfree.c
> > +++ b/fs/xfs/xfs_trans_extfree.c
> > @@ -68,7 +68,8 @@ xfs_trans_free_extent(
> >  	struct xfs_efd_log_item	*efdp,
> >  	xfs_fsblock_t		start_block,
> >  	xfs_extlen_t		ext_len,
> > -	struct xfs_owner_info	*oinfo)
> > +	struct xfs_owner_info	*oinfo,
> > +	bool			skip_discard)
> >  {
> >  	struct xfs_mount	*mp = tp->t_mountp;
> >  	uint			next_extent;
> > @@ -79,8 +80,12 @@ xfs_trans_free_extent(
> >  
> >  	trace_xfs_bmap_free_deferred(tp->t_mountp, agno, 0, agbno, ext_len);
> >  
> > -	error = xfs_free_extent(tp, start_block, ext_len, oinfo,
> > -			XFS_AG_RESV_NONE);
> > +	if (skip_discard)
> > +		error = xfs_free_extent_nodiscard(tp, start_block, ext_len,
> > +						  oinfo, XFS_AG_RESV_NONE);
> > +	else
> > +		error = xfs_free_extent(tp, start_block, ext_len, oinfo,
> > +					XFS_AG_RESV_NONE);
> >  
> >  	/*
> >  	 * Mark the transaction dirty, even on error. This ensures the
> > @@ -195,7 +200,7 @@ xfs_extent_free_finish_item(
> >  	error = xfs_trans_free_extent(tp, done_item,
> >  			free->xefi_startblock,
> >  			free->xefi_blockcount,
> > -			&free->xefi_oinfo);
> > +			&free->xefi_oinfo, free->xefi_skip_discard);
> >  	kmem_free(free);
> >  	return error;
> >  }
> > -- 
> > 2.14.3
> > 
> > --
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