Re: [PATCH 02/17] Set up infastructure for deferred attribute operations

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

On Wed, Oct 18, 2017 at 03:55:18PM -0700, Allison Henderson wrote:
> This patch adds two new log item types for setting or
> removing attributes as deferred operations.  The
> xfs_attri_log_item logs an intent to set or remove an
> attribute.  The corresponding xfs_attrd_log_item holds
> a reference to the xfs_attri_log_item and is freed once
> the transaction is done.  Both log items use a generic
> xfs_attr_log_format structure that contains the attribute
> name, value, flags, inode, and an op_flag that indicates
> if the operations is a set or remove.
> 
> At the moment, this feature will only be used by the parent
> pointer patch set which uses attributes to store information
> about an inodes parent.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
>  fs/xfs/Makefile                |   2 +
>  fs/xfs/libxfs/xfs_attr.c       |   2 +-
>  fs/xfs/libxfs/xfs_defer.h      |   1 +
>  fs/xfs/libxfs/xfs_log_format.h |  36 ++-
>  fs/xfs/libxfs/xfs_types.h      |   1 +
>  fs/xfs/xfs_attr.h              |  20 +-
>  fs/xfs/xfs_attr_item.c         | 512 +++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/xfs_attr_item.h         | 111 +++++++++
>  fs/xfs/xfs_log_recover.c       | 140 +++++++++++
>  fs/xfs/xfs_super.c             |   1 +
>  fs/xfs/xfs_trans.h             |  13 ++
>  fs/xfs/xfs_trans_attr.c        | 286 +++++++++++++++++++++++
>  12 files changed, 1121 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
> index a6e955b..ec6486b 100644
> --- a/fs/xfs/Makefile
> +++ b/fs/xfs/Makefile
> @@ -106,6 +106,7 @@ xfs-y				+= xfs_log.o \
>  				   xfs_bmap_item.o \
>  				   xfs_buf_item.o \
>  				   xfs_extfree_item.o \
> +				   xfs_attr_item.o \
>  				   xfs_icreate_item.o \
>  				   xfs_inode_item.o \
>  				   xfs_refcount_item.o \
> @@ -115,6 +116,7 @@ xfs-y				+= xfs_log.o \
>  				   xfs_trans_bmap.o \
>  				   xfs_trans_buf.o \
>  				   xfs_trans_extfree.o \
> +				   xfs_trans_attr.o \
>  				   xfs_trans_inode.o \
>  				   xfs_trans_refcount.o \
>  				   xfs_trans_rmap.o \
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index b00ec1f..5325ec2 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -74,7 +74,7 @@ STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
>  STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
>  
>  
> -STATIC int
> +int
>  xfs_attr_args_init(
>  	struct xfs_da_args	*args,
>  	struct xfs_inode	*dp,
> diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
> index d4f046d..ef0f8bf 100644
> --- a/fs/xfs/libxfs/xfs_defer.h
> +++ b/fs/xfs/libxfs/xfs_defer.h
> @@ -55,6 +55,7 @@ enum xfs_defer_ops_type {
>  	XFS_DEFER_OPS_TYPE_REFCOUNT,
>  	XFS_DEFER_OPS_TYPE_RMAP,
>  	XFS_DEFER_OPS_TYPE_FREE,
> +	XFS_DEFER_OPS_TYPE_ATTR,
>  	XFS_DEFER_OPS_TYPE_MAX,
>  };
>  
> diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
> index 8372e9b..b0ce87e 100644
> --- a/fs/xfs/libxfs/xfs_log_format.h
> +++ b/fs/xfs/libxfs/xfs_log_format.h
> @@ -18,6 +18,8 @@
>  #ifndef	__XFS_LOG_FORMAT_H__
>  #define __XFS_LOG_FORMAT_H__
>  
> +#include "xfs_attr.h"
> +
>  struct xfs_mount;
>  struct xfs_trans_res;
>  
> @@ -116,7 +118,12 @@ static inline uint xlog_get_cycle(char *ptr)
>  #define XLOG_REG_TYPE_CUD_FORMAT	24
>  #define XLOG_REG_TYPE_BUI_FORMAT	25
>  #define XLOG_REG_TYPE_BUD_FORMAT	26
> -#define XLOG_REG_TYPE_MAX		26
> +#define XLOG_REG_TYPE_ATTRI_FORMAT	27
> +#define XLOG_REG_TYPE_ATTRD_FORMAT	28
> +#define XLOG_REG_TYPE_ATTR_NAME		29
> +#define XLOG_REG_TYPE_ATTR_VALUE	30
> +#define XLOG_REG_TYPE_MAX		31
> +
>  
>  /*
>   * Flags to log operation header
> @@ -239,6 +246,8 @@ typedef struct xfs_trans_header {
>  #define	XFS_LI_CUD		0x1243
>  #define	XFS_LI_BUI		0x1244	/* bmbt update intent */
>  #define	XFS_LI_BUD		0x1245
> +#define	XFS_LI_ATTRI		0x1246  /* attr set/remove intent*/
> +#define	XFS_LI_ATTRD		0x1247  /* attr set/remove done */
>  
>  #define XFS_LI_TYPE_DESC \
>  	{ XFS_LI_EFI,		"XFS_LI_EFI" }, \
> @@ -254,7 +263,9 @@ typedef struct xfs_trans_header {
>  	{ XFS_LI_CUI,		"XFS_LI_CUI" }, \
>  	{ XFS_LI_CUD,		"XFS_LI_CUD" }, \
>  	{ XFS_LI_BUI,		"XFS_LI_BUI" }, \
> -	{ XFS_LI_BUD,		"XFS_LI_BUD" }
> +	{ XFS_LI_BUD,		"XFS_LI_BUD" }, \
> +	{ XFS_LI_ATTRI,		"XFS_LI_ATTRI" }, \
> +	{ XFS_LI_ATTRD,		"XFS_LI_ATTRD" }
>  
>  /*
>   * Inode Log Item Format definitions.
> @@ -863,4 +874,25 @@ struct xfs_icreate_log {
>  	__be32		icl_gen;	/* inode generation number to use */
>  };
>  
> +/* Flags for deferred attribute operations */
> +#define ATTR_OP_FLAGS_SET	0x01	/* Set the attribute */

The names need to have "XFS_" prefixed here because this is a public
header file, e.g. XFS_ATTR_OP_FLAGS_SET.

> +#define ATTR_OP_FLAGS_REMOVE	0x02	/* Remove the attribute */
> +#define ATTR_OP_FLAGS_MAX	0x02	/* Max flags */

I would be a little more explicit about which bits of op_flags are
actual bit flags and which parts are mutually exclusive type codes.
IOWs, from just these definitions here it's not clear that _SET and
_REMOVE can't both be set at the same time.

/* upper bits are flags, lower byte is type code */
#define XFS_ATTR_OP_FLAGS_SET		1
#define XFS_ATTR_OP_FLAGS_REMOVE	2
#define XFS_ATTR_OP_FLAGS_TYPE_MASK	0xFF

(TBH this opcode part could be an enum defined elsewhere like what RUI
pe_flags does...)

#define XFS_ATTR_OP_FLAGS_AFLAG		(1U << 31)
#define XFS_ATTR_OP_FLAGS_SOMEOTHERFLAG	(1U << 30)

> +
> +/*
> + * This is the structure used to lay out an attr log item in the
> + * log.
> + */
> +struct xfs_attr_log_format {
> +	uint64_t	id;		/* attri identifier */
> +	xfs_ino_t       ino;		/* the inode for this attr operation */
> +	uint32_t        op_flags;	/* marks the op as a set or remove */
> +	uint32_t        name_len;	/* attr name length */
> +	uint32_t        value_len;	/* attr value length */
> +	uint32_t        attr_flags;	/* attr flags */
> +	uint16_t	type;		/* attri log item type */
> +	uint16_t	size;		/* size of this item */
> +	uint32_t	pad;		/* pad to 64 bit aligned */

The names ought to have structure prefixes because this is a public header.

uint64_t	alf_id;
uint64_t	alf_ino;
...
uint32_t	alf_pad;

> +};
> +
>  #endif /* __XFS_LOG_FORMAT_H__ */
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index 0220159..5372063 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -23,6 +23,7 @@ typedef uint32_t	prid_t;		/* project ID */
>  typedef uint32_t	xfs_agblock_t;	/* blockno in alloc. group */
>  typedef uint32_t	xfs_agino_t;	/* inode # within allocation grp */
>  typedef uint32_t	xfs_extlen_t;	/* extent length in blocks */
> +typedef uint32_t	xfs_attrlen_t;	/* attr length */
>  typedef uint32_t	xfs_agnumber_t;	/* allocation group number */
>  typedef int32_t		xfs_extnum_t;	/* # of extents in a file */
>  typedef int16_t		xfs_aextnum_t;	/* # extents in an attribute fork */
> diff --git a/fs/xfs/xfs_attr.h b/fs/xfs/xfs_attr.h
> index 8542606..34bb4cb 100644
> --- a/fs/xfs/xfs_attr.h
> +++ b/fs/xfs/xfs_attr.h
> @@ -18,6 +18,8 @@
>  #ifndef __XFS_ATTR_H__
>  #define	__XFS_ATTR_H__
>  
> +#include "libxfs/xfs_defer.h"

What does this header file need from xfs_defer.h?

>  struct xfs_inode;
>  struct xfs_da_args;
>  struct xfs_attr_list_context;
> @@ -87,6 +89,20 @@ typedef struct attrlist_ent {	/* data from attr_list() */
>  } attrlist_ent_t;
>  
>  /*
> + * List of attrs to commit later.
> + */
> +struct xfs_attr_item {
> +	xfs_ino_t	  xattri_ino;
> +	uint32_t	  xattri_op_flags;
> +	uint32_t	  xattri_value_len;   /* length of name and val */
> +	uint32_t	  xattri_name_len;    /* length of name */
> +	uint32_t	  xattri_flags;       /* attr flags */
> +	char		  xattri_name[XATTR_NAME_MAX];
> +	char              xattri_value[XATTR_SIZE_MAX];

MAXNAMELEN and XFS_XATTR_SIZE_MAX ?

(Ugh, really, we should just clean that up to XFS_MAXNAMELEN...)

> +	struct list_head  xattri_list;
> +};
> +
> +/*
>   * Given a pointer to the (char*) buffer containing the attr_list() result,
>   * and an index, return a pointer to the indicated attribute in the buffer.
>   */
> @@ -154,6 +170,8 @@ int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name, int flags);
>  int xfs_attr_remove_args(struct xfs_da_args *args, int flags);
>  int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
>  		  int flags, struct attrlist_cursor_kern *cursor);
> -
> +int xfs_attr_args_init(struct xfs_da_args *args, struct xfs_inode *dp,
> +		       const unsigned char *name, int flags);
> +int xfs_attr_calc_size(struct xfs_da_args *args, int *local);
>  
>  #endif	/* __XFS_ATTR_H__ */
> diff --git a/fs/xfs/xfs_attr_item.c b/fs/xfs/xfs_attr_item.c
> new file mode 100644
> index 0000000..8cbe9b0
> --- /dev/null
> +++ b/fs/xfs/xfs_attr_item.c
> @@ -0,0 +1,512 @@
> +/*
> + * Copyright (c) 2017 Oracle, Inc.
> + * All Rights Reserved.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it would be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write the Free Software Foundation Inc.
> + */
> +#include "xfs.h"
> +#include "xfs_fs.h"
> +#include "xfs_format.h"
> +#include "xfs_log_format.h"
> +#include "xfs_trans_resv.h"
> +#include "xfs_bit.h"
> +#include "xfs_mount.h"
> +#include "xfs_trans.h"
> +#include "xfs_trans_priv.h"
> +#include "xfs_buf_item.h"
> +#include "xfs_attr_item.h"
> +#include "xfs_log.h"
> +#include "xfs_btree.h"
> +#include "xfs_rmap.h"
> +
> +
> +static inline struct xfs_attri_log_item *ATTRI_ITEM(struct xfs_log_item *lip)
> +{
> +	return container_of(lip, struct xfs_attri_log_item, item);
> +}
> +
> +void
> +xfs_attri_item_free(
> +	struct xfs_attri_log_item	*attrip)
> +{
> +	kmem_free(attrip->item.li_lv_shadow);
> +	kmem_free(attrip);
> +}
> +
> +/*
> + * This returns the number of iovecs needed to log the given attri item.
> + * We only need 1 iovec for an attri item.  It just logs the attr_log_format
> + * structure.
> + */
> +static inline int
> +xfs_attri_item_sizeof(
> +	struct xfs_attri_log_item *attrip)
> +{
> +	return sizeof(struct xfs_attr_log_format);
> +}
> +
> +STATIC void
> +xfs_attri_item_size(
> +	struct xfs_log_item	*lip,
> +	int			*nvecs,
> +	int			*nbytes)
> +{
> +	struct xfs_attri_log_item       *attrip = ATTRI_ITEM(lip);
> +
> +	*nvecs += 1;
> +	*nbytes += xfs_attri_item_sizeof(attrip);
> +
> +	if (attrip->name_len > 0) {
> +		*nvecs += 1;
> +		nbytes += attrip->name_len;
> +	}
> +
> +	if (attrip->value_len > 0) {
> +		*nvecs += 1;
> +		nbytes += attrip->value_len;
> +	}
> +}
> +
> +/*
> + * This is called to fill in the vector of log iovecs for the
> + * given attri log item. We use only 1 iovec, and we point that
> + * at the attri_log_format structure embedded in the attri item.
> + * It is at this point that we assert that all of the attr
> + * slots in the attri item have been filled.
> + */
> +STATIC void
> +xfs_attri_item_format(
> +	struct xfs_log_item	*lip,
> +	struct xfs_log_vec	*lv)
> +{
> +	struct xfs_attri_log_item	*attrip = ATTRI_ITEM(lip);
> +	struct xfs_log_iovec	*vecp = NULL;
> +
> +	attrip->format.type = XFS_LI_ATTRI;
> +	attrip->format.size = 1;
> +
> +	xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTRI_FORMAT,
> +			&attrip->format,
> +			xfs_attri_item_sizeof(attrip));
> +	if (attrip->name_len > 0)
> +		xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTR_NAME,
> +				attrip->name, attrip->name_len);
> +
> +	if (attrip->value_len > 0)
> +		xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTR_VALUE,
> +				attrip->value, attrip->value_len);
> +}
> +
> +
> +/*
> + * Pinning has no meaning for an attri item, so just return.
> + */
> +STATIC void
> +xfs_attri_item_pin(
> +	struct xfs_log_item	*lip)
> +{
> +}
> +
> +/*
> + * The unpin operation is the last place an ATTRI is manipulated in the log. It
> + * is either inserted in the AIL or aborted in the event of a log I/O error. In
> + * either case, the EFI transaction has been successfully committed to make it

EFI?

> + * this far. Therefore, we expect whoever committed the ATTRI to either
> + * construct and commit the ATTRD or drop the ATTRD's reference in the event of
> + * error. Simply drop the log's ATTRI reference now that the log is done with
> + * it.
> + */
> +STATIC void
> +xfs_attri_item_unpin(
> +	struct xfs_log_item	*lip,
> +	int			remove)
> +{
> +	struct xfs_attri_log_item	*attrip = ATTRI_ITEM(lip);
> +
> +	xfs_attri_release(attrip);
> +}
> +
> +/*
> + * attri items have no locking or pushing.  However, since ATTRIs are pulled
> + * from the AIL when their corresponding ATTRDs are committed to disk, their
> + * situation is very similar to being pinned.  Return XFS_ITEM_PINNED so that
> + * the caller will eventually flush the log.  This should help in getting the
> + * ATTRI out of the AIL.
> + */
> +STATIC uint
> +xfs_attri_item_push(
> +	struct xfs_log_item	*lip,
> +	struct list_head	*buffer_list)
> +{
> +	return XFS_ITEM_PINNED;
> +}
> +
> +/*
> + * The ATTRI has been either committed or aborted if the transaction has been
> + * cancelled. If the transaction was cancelled, an ATTRD isn't going to be
> + * constructed and thus we free the ATTRI here directly.
> + */
> +STATIC void
> +xfs_attri_item_unlock(
> +	struct xfs_log_item	*lip)
> +{
> +	if (lip->li_flags & XFS_LI_ABORTED)
> +		xfs_attri_item_free(ATTRI_ITEM(lip));
> +}
> +
> +/*
> + * The ATTRI is logged only once and cannot be moved in the log, so simply
> + * return the lsn at which it's been logged.
> + */
> +STATIC xfs_lsn_t
> +xfs_attri_item_committed(
> +	struct xfs_log_item	*lip,
> +	xfs_lsn_t		lsn)
> +{
> +	return lsn;
> +}
> +
> +STATIC void
> +xfs_attri_item_committing(
> +	struct xfs_log_item	*lip,
> +	xfs_lsn_t		lsn)
> +{
> +}
> +
> +/*
> + * This is the ops vector shared by all attri log items.
> + */
> +static const struct xfs_item_ops xfs_attri_item_ops = {
> +	.iop_size	= xfs_attri_item_size,
> +	.iop_format	= xfs_attri_item_format,
> +	.iop_pin	= xfs_attri_item_pin,
> +	.iop_unpin	= xfs_attri_item_unpin,
> +	.iop_unlock	= xfs_attri_item_unlock,
> +	.iop_committed	= xfs_attri_item_committed,
> +	.iop_push	= xfs_attri_item_push,
> +	.iop_committing = xfs_attri_item_committing
> +};
> +
> +
> +/*
> + * Allocate and initialize an attri item
> + */
> +struct xfs_attri_log_item *
> +xfs_attri_init(
> +	struct xfs_mount	*mp)
> +
> +{
> +	struct xfs_attri_log_item	*attrip;
> +	uint			size;
> +
> +	size = (uint)(sizeof(struct xfs_attri_log_item));
> +	attrip = kmem_zalloc(size, KM_SLEEP);
> +
> +	xfs_log_item_init(mp, &(attrip->item), XFS_LI_ATTRI,
> +			  &xfs_attri_item_ops);
> +	attrip->format.id = (uintptr_t)(void *)attrip;
> +	atomic_set(&attrip->refcount, 2);
> +
> +	return attrip;
> +}
> +
> +/*
> + * Copy an attr format buffer from the given buf, and into the destination
> + * attr format structure.
> + */
> +int
> +xfs_attr_copy_format(struct xfs_log_iovec *buf,
> +		      struct xfs_attr_log_format *dst_attr_fmt)
> +{
> +	struct xfs_attr_log_format *src_attr_fmt = buf->i_addr;
> +	uint len = sizeof(struct xfs_attr_log_format);
> +
> +	if (buf->i_len == len) {
> +		memcpy((char *)dst_attr_fmt, (char *)src_attr_fmt, len);
> +		return 0;
> +	}
> +	return -EFSCORRUPTED;
> +}
> +
> +/*
> + * Freeing the attri requires that we remove it from the AIL if it has already
> + * been placed there. However, the ATTRI may not yet have been placed in the
> + * AIL when called by xfs_attri_release() from ATTRD processing due to the
> + * ordering of committed vs unpin operations in bulk insert operations. Hence
> + * the reference count to ensure only the last caller frees the ATTRI.
> + */
> +void
> +xfs_attri_release(
> +	struct xfs_attri_log_item	*attrip)
> +{
> +	ASSERT(atomic_read(&attrip->refcount) > 0);
> +	if (atomic_dec_and_test(&attrip->refcount)) {
> +		xfs_trans_ail_remove(&attrip->item,
> +				     SHUTDOWN_LOG_IO_ERROR);
> +		xfs_attri_item_free(attrip);
> +	}
> +}
> +
> +static inline struct xfs_attrd_log_item *ATTRD_ITEM(struct xfs_log_item *lip)
> +{
> +	return container_of(lip, struct xfs_attrd_log_item, item);
> +}
> +
> +STATIC void
> +xfs_attrd_item_free(struct xfs_attrd_log_item *attrdp)
> +{
> +	kmem_free(attrdp->item.li_lv_shadow);
> +	kmem_free(attrdp);
> +}
> +
> +/*
> + * This returns the number of iovecs needed to log the given attrd item.
> + * We only need 1 iovec for an attrd item.  It just logs the attr_log_format
> + * structure.
> + */
> +static inline int
> +xfs_attrd_item_sizeof(
> +	struct xfs_attrd_log_item *attrdp)
> +{
> +	return sizeof(struct xfs_attr_log_format);
> +}
> +
> +STATIC void
> +xfs_attrd_item_size(
> +	struct xfs_log_item	*lip,
> +	int			*nvecs,
> +	int			*nbytes)
> +{
> +	struct xfs_attrd_log_item	*attrdp = ATTRD_ITEM(lip);
> +	*nvecs += 1;
> +	*nbytes += xfs_attrd_item_sizeof(attrdp);
> +
> +	if (attrdp->name_len > 0) {
> +		*nvecs += 1;
> +		nbytes += attrdp->name_len;
> +	}
> +
> +	if (attrdp->value_len > 0) {
> +		*nvecs += 1;
> +		nbytes += attrdp->value_len;
> +	}
> +}
> +
> +/*
> + * This is called to fill in the vector of log iovecs for the
> + * given attrd log item. We use only 1 iovec, and we point that
> + * at the attr_log_format structure embedded in the attrd item.
> + * It is at this point that we assert that all of the attr
> + * slots in the attrd item have been filled.
> + */
> +STATIC void
> +xfs_attrd_item_format(
> +	struct xfs_log_item	*lip,
> +	struct xfs_log_vec	*lv)
> +{
> +	struct xfs_attrd_log_item	*attrdp = ATTRD_ITEM(lip);
> +	struct xfs_log_iovec	*vecp = NULL;
> +
> +	attrdp->format.type = XFS_LI_ATTRD;
> +	attrdp->format.size = 1;
> +
> +	xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTRD_FORMAT,
> +			&attrdp->format,
> +			xfs_attrd_item_sizeof(attrdp));
> +
> +	if (attrdp->name_len > 0)
> +		xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTR_NAME,
> +				attrdp->name, attrdp->name_len);
> +
> +	if (attrdp->value_len > 0)
> +		xlog_copy_iovec(lv, &vecp, XLOG_REG_TYPE_ATTR_VALUE,
> +				attrdp->value, attrdp->value_len);

No need to log name/value for ATTRD items, since we only care about
matching alf_id between ATTRI and ATTRD items.

> +}
> +
> +/*
> + * Pinning has no meaning for an attrd item, so just return.
> + */
> +STATIC void
> +xfs_attrd_item_pin(
> +	struct xfs_log_item	*lip)
> +{
> +}
> +
> +/*
> + * Since pinning has no meaning for an attrd item, unpinning does
> + * not either.
> + */
> +STATIC void
> +xfs_attrd_item_unpin(
> +	struct xfs_log_item	*lip,
> +	int			remove)
> +{
> +}
> +
> +/*
> + * There isn't much you can do to push on an attrd item.  It is simply stuck
> + * waiting for the log to be flushed to disk.
> + */
> +STATIC uint
> +xfs_attrd_item_push(
> +	struct xfs_log_item	*lip,
> +	struct list_head	*buffer_list)
> +{
> +	return XFS_ITEM_PINNED;
> +}
> +
> +/*
> + * The ATTRD is either committed or aborted if the transaction is cancelled. If
> + * the transaction is cancelled, drop our reference to the ATTRI and free the
> + * ATTRD.
> + */
> +STATIC void
> +xfs_attrd_item_unlock(
> +	struct xfs_log_item	*lip)
> +{
> +	struct xfs_attrd_log_item	*attrdp = ATTRD_ITEM(lip);
> +
> +	if (lip->li_flags & XFS_LI_ABORTED) {
> +		xfs_attri_release(attrdp->attrip);
> +		xfs_attrd_item_free(attrdp);
> +	}
> +}
> +
> +/*
> + * When the attrd item is committed to disk, all we need to do is delete our
> + * reference to our partner attri item and then free ourselves. Since we're
> + * freeing ourselves we must return -1 to keep the transaction code from
> + * further referencing this item.
> + */
> +STATIC xfs_lsn_t
> +xfs_attrd_item_committed(
> +	struct xfs_log_item	*lip,
> +	xfs_lsn_t		lsn)
> +{
> +	struct xfs_attrd_log_item	*attrdp = ATTRD_ITEM(lip);
> +
> +	/*
> +	 * Drop the ATTRI reference regardless of whether the ATTRD has been
> +	 * aborted. Once the ATTRD transaction is constructed, it is the sole
> +	 * responsibility of the ATTRD to release the ATTRI (even if the ATTRI
> +	 * is aborted due to log I/O error).
> +	 */
> +	xfs_attri_release(attrdp->attrip);
> +	xfs_attrd_item_free(attrdp);
> +
> +	return (xfs_lsn_t)-1;
> +}
> +
> +STATIC void
> +xfs_attrd_item_committing(
> +	struct xfs_log_item	*lip,
> +	xfs_lsn_t		lsn)
> +{
> +}
> +
> +/*
> + * This is the ops vector shared by all attrd log items.
> + */
> +static const struct xfs_item_ops xfs_attrd_item_ops = {
> +	.iop_size	= xfs_attrd_item_size,
> +	.iop_format	= xfs_attrd_item_format,
> +	.iop_pin	= xfs_attrd_item_pin,
> +	.iop_unpin	= xfs_attrd_item_unpin,
> +	.iop_unlock	= xfs_attrd_item_unlock,
> +	.iop_committed	= xfs_attrd_item_committed,
> +	.iop_push	= xfs_attrd_item_push,
> +	.iop_committing = xfs_attrd_item_committing
> +};
> +
> +/*
> + * Allocate and initialize an attrd item
> + */
> +struct xfs_attrd_log_item *
> +xfs_attrd_init(
> +	struct xfs_mount	*mp,
> +	struct xfs_attri_log_item	*attrip)
> +
> +{
> +	struct xfs_attrd_log_item	*attrdp;
> +	uint			size;
> +
> +	size = (uint)(sizeof(struct xfs_attrd_log_item));
> +	attrdp = kmem_zalloc(size, KM_SLEEP);
> +
> +	xfs_log_item_init(mp, &attrdp->item, XFS_LI_ATTRD,
> +			  &xfs_attrd_item_ops);
> +	attrdp->attrip = attrip;
> +	attrdp->format.id = attrip->format.id;
> +
> +	return attrdp;
> +}
> +
> +/*
> + * Process an attr intent item that was recovered from
> + * the log.  We need to delete the attr that it describes.
> + */
> +int
> +xfs_attri_recover(
> +	struct xfs_mount	*mp,
> +	struct xfs_attri_log_item	*attrip)
> +{
> +	struct xfs_attrd_log_item	*attrdp;
> +	struct xfs_trans	*tp;
> +	int			error = 0;
> +	struct xfs_attr_log_format	*attrp;
> +
> +	ASSERT(!test_bit(XFS_ATTRI_RECOVERED, &attrip->flags));
> +
> +	/*
> +	 * First check the validity of the attr described by the
> +	 * ATTRI.  If any are bad, then assume that all are bad and
> +	 * just toss the ATTRI.
> +	 */
> +	attrp = &attrip->format;
> +	if (attrp->value_len == 0 ||
> +	    attrp->name_len == 0 ||
> +	    attrp->op_flags > ATTR_OP_FLAGS_MAX) {
> +		/*
> +		 * This will pull the ATTRI from the AIL and
> +		 * free the memory associated with it.
> +		 */
> +		set_bit(XFS_ATTRI_RECOVERED, &attrip->flags);
> +		xfs_attri_release(attrip);
> +		return -EIO;
> +	}
> +
> +	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
> +	if (error)
> +		return error;
> +	attrdp = xfs_trans_get_attrd(tp, attrip);
> +	attrp = &attrip->format;
> +
> +	error = xfs_trans_attr(tp, attrdp, attrp->ino,
> +				attrp->op_flags,
> +				attrp->attr_flags,
> +				attrp->name_len,
> +				attrp->value_len,
> +				attrip->name,
> +				attrip->value);
> +	if (error)
> +		goto abort_error;
> +
> +
> +	set_bit(XFS_ATTRI_RECOVERED, &attrip->flags);
> +	error = xfs_trans_commit(tp);
> +	return error;
> +
> +abort_error:
> +	xfs_trans_cancel(tp);
> +	return error;
> +}
> diff --git a/fs/xfs/xfs_attr_item.h b/fs/xfs/xfs_attr_item.h
> new file mode 100644
> index 0000000..023675d
> --- /dev/null
> +++ b/fs/xfs/xfs_attr_item.h
> @@ -0,0 +1,111 @@
> +/*
> + * Copyright (c) 2017 Oracle, Inc.
> + * All Rights Reserved.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it would be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write the Free Software Foundation Inc.
> + */
> +#ifndef	__XFS_ATTR_ITEM_H__
> +#define	__XFS_ATTR_ITEM_H__
> +
> +/* kernel only ATTRI/ATTRD definitions */
> +
> +struct xfs_mount;
> +struct kmem_zone;
> +
> +/*
> + * Max number of attrs in fast allocation path.
> + */
> +#define XFS_ATTRI_MAX_FAST_ATTRS        16

Daaaang, we can cram *sixteen* different attribute name/value updates in
a single defer_ops item? :)

Each defer_ops item gets its own transaction to make changes and log the
done item.  Sixteen attr updates is a /lot/ to be pushing through one
transaction since (AFAICT) the static log reservations provide worst
case space for one update.  I think this ought to be 1, especially since
the actual attr log item structure only appears to have space to store
one name and one value.

> +
> +
> +/*
> + * Define ATTR flag bits. Manipulated by set/clear/test_bit operators.
> + */
> +#define	XFS_ATTRI_RECOVERED	1
> +
> +/*
> + * This is the "attr intention" log item.  It is used to log the fact
> + * that some attrs need to be processed.  It is used in conjunction with the
> + * "attr done" log item described below.
> + *
> + * The ATTRI is reference counted so that it is not freed prior to both the
> + * ATTRI and ATTRD being committed and unpinned. This ensures the ATTRI is
> + * inserted into the AIL even in the event of out of order ATTRI/ATTRD
> + * processing. In other words, an ATTRI is born with two references:
> + *
> + *      1.) an ATTRI held reference to track ATTRI AIL insertion
> + *      2.) an ATTRD held reference to track ATTRD commit
> + *
> + * On allocation, both references are the responsibility of the caller. Once
> + * the ATTRI is added to and dirtied in a transaction, ownership of reference
> + * one transfers to the transaction. The reference is dropped once the ATTRI is
> + * inserted to the AIL or in the event of failure along the way (e.g., commit
> + * failure, log I/O error, etc.). Note that the caller remains responsible for
> + * the ATTRD reference under all circumstances to this point. The caller has no
> + * means to detect failure once the transaction is committed, however.
> + * Therefore, an ATTRD is required after this point, even in the event of
> + * unrelated failure.
> + *
> + * Once an ATTRD is allocated and dirtied in a transaction, reference two
> + * transfers to the transaction. The ATTRD reference is dropped once it reaches
> + * the unpin handler. Similar to the ATTRI, the reference also drops in the
> + * event of commit failure or log I/O errors. Note that the ATTRD is not
> + * inserted in the AIL, so at this point both the ATTI and ATTRD are freed.
> + */
> +struct xfs_attri_log_item {
> +	xfs_log_item_t			item;
> +	atomic_t			refcount;
> +	unsigned long			flags;	/* misc flags */
> +	int				name_len;
> +	void				*name;
> +	int				value_len;
> +	void				*value;
> +	struct xfs_attr_log_format	format;
> +};
> +
> +/*
> + * This is the "attr done" log item.  It is used to log
> + * the fact that some attrs earlier mentioned in an attri item
> + * have been freed.
> + */
> +struct xfs_attrd_log_item {
> +	struct xfs_log_item		item;
> +	struct xfs_attri_log_item	*attrip;
> +	uint				next_attr;
> +	int				name_len;
> +	void				*name;
> +	int				value_len;
> +	void				*value;
> +	struct xfs_attr_log_format	format;
> +};
> +
> +/*
> + * Max number of attrs in fast allocation path.
> + */
> +#define	XFS_ATTRD_MAX_FAST_ATTRS	16
> +
> +extern struct kmem_zone	*xfs_attri_zone;
> +extern struct kmem_zone	*xfs_attrd_zone;
> +
> +struct xfs_attri_log_item	*xfs_attri_init(struct xfs_mount *mp);
> +struct xfs_attrd_log_item	*xfs_attrd_init(struct xfs_mount *mp,
> +					struct xfs_attri_log_item *attrip);
> +int xfs_attr_copy_format(struct xfs_log_iovec *buf,
> +			 struct xfs_attr_log_format *dst_attri_fmt);
> +void			xfs_attri_item_free(struct xfs_attri_log_item *attrip);
> +void			xfs_attri_release(struct xfs_attri_log_item *attrip);
> +
> +int			xfs_attri_recover(struct xfs_mount *mp,
> +					struct xfs_attri_log_item *attrip);
> +
> +#endif	/* __XFS_ATTR_ITEM_H__ */
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index ee34899..8326f56 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -33,6 +33,7 @@
>  #include "xfs_log_recover.h"
>  #include "xfs_inode_item.h"
>  #include "xfs_extfree_item.h"
> +#include "xfs_attr_item.h"
>  #include "xfs_trans_priv.h"
>  #include "xfs_alloc.h"
>  #include "xfs_ialloc.h"
> @@ -1956,6 +1957,8 @@ xlog_recover_reorder_trans(
>  		case XFS_LI_CUD:
>  		case XFS_LI_BUI:
>  		case XFS_LI_BUD:
> +		case XFS_LI_ATTRI:
> +		case XFS_LI_ATTRD:
>  			trace_xfs_log_recover_item_reorder_tail(log,
>  							trans, item, pass);
>  			list_move_tail(&item->ri_list, &inode_list);
> @@ -3489,6 +3492,92 @@ xlog_recover_efd_pass2(
>  	return 0;
>  }
>  
> +STATIC int
> +xlog_recover_attri_pass2(
> +	struct xlog                     *log,
> +	struct xlog_recover_item        *item,
> +	xfs_lsn_t                       lsn)
> +{
> +	int                             error;
> +	struct xfs_mount                *mp = log->l_mp;
> +	struct xfs_attri_log_item       *attrip;
> +	struct xfs_attr_log_format     *attri_formatp;
> +
> +	attri_formatp = item->ri_buf[0].i_addr;
> +
> +	attrip = xfs_attri_init(mp);
> +	error = xfs_attr_copy_format(&item->ri_buf[0], &attrip->format);
> +	if (error) {
> +		xfs_attri_item_free(attrip);
> +		return error;
> +	}
> +
> +	spin_lock(&log->l_ailp->xa_lock);
> +	/*
> +	 * The ATTRI has two references. One for the ATTRD and one for ATTRI to
> +	 * ensure it makes it into the AIL. Insert the ATTRI into the AIL
> +	 * directly and drop the ATTRI reference. Note that
> +	 * xfs_trans_ail_update() drops the AIL lock.
> +	 */
> +	xfs_trans_ail_update(log->l_ailp, &attrip->item, lsn);
> +	xfs_attri_release(attrip);
> +	return 0;
> +}
> +
> +
> +/*
> + * This routine is called when an ATTRD format structure is found in a committed
> + * transaction in the log. Its purpose is to cancel the corresponding ATTRI if
> + * it was still in the log. To do this it searches the AIL for the ATTRI with
> + * an id equal to that in the ATTRD format structure. If we find it we drop
> + * the ATTRD reference, which removes the ATTRI from the AIL and frees it.
> + */
> +STATIC int
> +xlog_recover_attrd_pass2(
> +	struct xlog                     *log,
> +	struct xlog_recover_item        *item)
> +{
> +	struct xfs_attr_log_format    *attrd_formatp;
> +	struct xfs_attri_log_item      *attrip = NULL;
> +	struct xfs_log_item          *lip;
> +	uint64_t                attri_id;
> +	struct xfs_ail_cursor   cur;
> +	struct xfs_ail          *ailp = log->l_ailp;
> +
> +	attrd_formatp = item->ri_buf[0].i_addr;
> +	ASSERT((item->ri_buf[0].i_len ==
> +				(sizeof(struct xfs_attr_log_format))));
> +	attri_id = attrd_formatp->id;
> +
> +	/*
> +	 * Search for the ATTRI with the id in the ATTRD format structure in the
> +	 * AIL.
> +	 */
> +	spin_lock(&ailp->xa_lock);
> +	lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
> +	while (lip != NULL) {
> +		if (lip->li_type == XFS_LI_ATTRI) {
> +			attrip = (struct xfs_attri_log_item *)lip;
> +			if (attrip->format.id == attri_id) {
> +				/*
> +				 * Drop the ATTRD reference to the ATTRI. This
> +				 * removes the ATTRI from the AIL and frees it.
> +				 */
> +				spin_unlock(&ailp->xa_lock);
> +				xfs_attri_release(attrip);
> +				spin_lock(&ailp->xa_lock);
> +				break;
> +			}
> +		}
> +		lip = xfs_trans_ail_cursor_next(ailp, &cur);
> +	}
> +
> +	xfs_trans_ail_cursor_done(&cur);
> +	spin_unlock(&ailp->xa_lock);
> +
> +	return 0;
> +}
> +
>  /*
>   * This routine is called to create an in-core extent rmap update
>   * item from the rui format structure which was logged on disk.
> @@ -4108,6 +4197,10 @@ xlog_recover_commit_pass2(
>  		return xlog_recover_efi_pass2(log, item, trans->r_lsn);
>  	case XFS_LI_EFD:
>  		return xlog_recover_efd_pass2(log, item);
> +	case XFS_LI_ATTRI:
> +		return xlog_recover_attri_pass2(log, item, trans->r_lsn);
> +	case XFS_LI_ATTRD:
> +		return xlog_recover_attrd_pass2(log, item);
>  	case XFS_LI_RUI:
>  		return xlog_recover_rui_pass2(log, item, trans->r_lsn);
>  	case XFS_LI_RUD:
> @@ -4669,6 +4762,49 @@ xlog_recover_cancel_efi(
>  	spin_lock(&ailp->xa_lock);
>  }
>  
> +/* Recover the ATTRI if necessary. */
> +STATIC int
> +xlog_recover_process_attri(
> +	struct xfs_mount                *mp,
> +	struct xfs_ail                  *ailp,
> +	struct xfs_log_item             *lip)
> +{
> +	struct xfs_attri_log_item       *attrip;
> +	int                             error;
> +
> +	/*
> +	 * Skip ATTRIs that we've already processed.
> +	 */
> +	attrip = container_of(lip, struct xfs_attri_log_item, item);
> +	if (test_bit(XFS_ATTRI_RECOVERED, &attrip->flags))
> +		return 0;
> +
> +	spin_unlock(&ailp->xa_lock);
> +	error = xfs_attri_recover(mp, attrip);
> +	spin_lock(&ailp->xa_lock);
> +
> +	return error;
> +}
> +
> +/* Release the ATTRI since we're cancelling everything. */
> +STATIC void
> +xlog_recover_cancel_attri(
> +	struct xfs_mount                *mp,
> +	struct xfs_ail                  *ailp,
> +	struct xfs_log_item             *lip)
> +{
> +	struct xfs_attri_log_item         *attrip;
> +
> +	attrip = container_of(lip, struct xfs_attri_log_item, item);
> +
> +	spin_unlock(&ailp->xa_lock);
> +	xfs_attri_release(attrip);
> +	spin_lock(&ailp->xa_lock);
> +}
> +
> +
> +
> +
>  /* Recover the RUI if necessary. */
>  STATIC int
>  xlog_recover_process_rui(
> @@ -4861,6 +4997,10 @@ xlog_recover_process_intents(
>  		case XFS_LI_EFI:
>  			error = xlog_recover_process_efi(log->l_mp, ailp, lip);
>  			break;
> +		case XFS_LI_ATTRI:
> +			error = xlog_recover_process_attri(log->l_mp,
> +							   ailp, lip);

FWIW you're allowed (in xfs land only) to use the double-indent
convention:

error = xlog_recover_process_attri(log->l_mp,
		ailp, lip);

Instead of spending time lining things up with the '('.

> +			break;
>  		case XFS_LI_RUI:
>  			error = xlog_recover_process_rui(log->l_mp, ailp, lip);
>  			break;
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 584cf2d..046ced4 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -2024,6 +2024,7 @@ init_xfs_fs(void)
>  	xfs_rmap_update_init_defer_op();
>  	xfs_refcount_update_init_defer_op();
>  	xfs_bmap_update_init_defer_op();
> +	xfs_attr_init_defer_op();
>  
>  	xfs_dir_startup();
>  
> diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
> index 815b53d2..d003637 100644
> --- a/fs/xfs/xfs_trans.h
> +++ b/fs/xfs/xfs_trans.h
> @@ -40,6 +40,9 @@ struct xfs_cud_log_item;
>  struct xfs_defer_ops;
>  struct xfs_bui_log_item;
>  struct xfs_bud_log_item;
> +struct xfs_attrd_log_item;
> +struct xfs_attri_log_item;
> +
>  
>  typedef struct xfs_log_item {
>  	struct list_head		li_ail;		/* AIL pointers */
> @@ -223,12 +226,22 @@ void		xfs_trans_dirty_buf(struct xfs_trans *, struct xfs_buf *);
>  void		xfs_trans_log_inode(xfs_trans_t *, struct xfs_inode *, uint);
>  
>  void		xfs_extent_free_init_defer_op(void);
> +void            xfs_attr_init_defer_op(void);
> +
>  struct xfs_efd_log_item	*xfs_trans_get_efd(struct xfs_trans *,
>  				  struct xfs_efi_log_item *,
>  				  uint);
>  int		xfs_trans_free_extent(struct xfs_trans *,
>  				      struct xfs_efd_log_item *, xfs_fsblock_t,
>  				      xfs_extlen_t, struct xfs_owner_info *);
> +struct xfs_attrd_log_item *
> +xfs_trans_get_attrd(struct xfs_trans *tp,
> +		    struct xfs_attri_log_item *attrip);
> +int xfs_trans_attr(struct xfs_trans *tp, struct xfs_attrd_log_item *attrdp,
> +			xfs_ino_t ino, uint32_t attr_op_flags, uint32_t flags,
> +			uint32_t name_len, uint32_t value_len,
> +			char *name, char *value);
> +
>  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_attr.c b/fs/xfs/xfs_trans_attr.c
> new file mode 100644
> index 0000000..39eb18d
> --- /dev/null
> +++ b/fs/xfs/xfs_trans_attr.c
> @@ -0,0 +1,286 @@
> +/*
> + * Copyright (c) 2017, Oracle Inc.
> + * All Rights Reserved.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it would be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write the Free Software Foundation Inc.
> + */
> +#include "xfs.h"
> +#include "xfs_fs.h"
> +#include "xfs_shared.h"
> +#include "xfs_format.h"
> +#include "xfs_log_format.h"
> +#include "xfs_trans_resv.h"
> +#include "xfs_bit.h"
> +#include "xfs_mount.h"
> +#include "xfs_defer.h"
> +#include "xfs_trans.h"
> +#include "xfs_trans_priv.h"
> +#include "xfs_attr_item.h"
> +#include "xfs_alloc.h"
> +#include "xfs_bmap.h"
> +#include "xfs_trace.h"
> +#include "libxfs/xfs_da_format.h"
> +#include "xfs_da_btree.h"
> +#include "xfs_attr.h"
> +#include "xfs_inode.h"
> +#include "xfs_icache.h"
> +
> +/*
> + * This routine is called to allocate an "extent free done"
> + * log item that will hold nextents worth of extents.  The
> + * caller must use all nextents extents, because we are not
> + * flexible about this at all.
> + */
> +struct xfs_attrd_log_item *
> +xfs_trans_get_attrd(struct xfs_trans		*tp,
> +		  struct xfs_attri_log_item	*attrip)
> +{
> +	struct xfs_attrd_log_item			*attrdp;
> +
> +	ASSERT(tp != NULL);
> +
> +	attrdp = xfs_attrd_init(tp->t_mountp, attrip);
> +	ASSERT(attrdp != NULL);
> +
> +	/*
> +	 * Get a log_item_desc to point at the new item.
> +	 */
> +	xfs_trans_add_item(tp, &attrdp->item);
> +	return attrdp;
> +}
> +
> +/*
> + * Delete an attr and log it to the ATTRD. Note that the transaction is marked
> + * dirty regardless of whether the attr delete succeeds or fails to support the
> + * ATTRI/ATTRD lifecycle rules.
> + */
> +int
> +xfs_trans_attr(
> +	struct xfs_trans	*tp,
> +	struct xfs_attrd_log_item	*attrdp,
> +	xfs_ino_t		ino,
> +	uint32_t		op_flags,
> +	uint32_t                flags,
> +	uint32_t		name_len,
> +	uint32_t		value_len,
> +	char			*name,
> +	char			*value)
> +{
> +	uint			next_attr;
> +	struct xfs_attr_log_format *attrp;
> +	int			error;
> +	int                     local;
> +	struct xfs_da_args      args;
> +	struct xfs_inode	*dp;
> +	struct xfs_defer_ops    dfops;
> +	xfs_fsblock_t		firstblock = NULLFSBLOCK;
> +	struct xfs_mount	*mp = tp->t_mountp;
> +
> +	error = xfs_iget(mp, tp, ino, flags, 0, &dp);
> +	if (error)
> +		return error;
> +
> +	ASSERT(XFS_IFORK_Q((dp)));
> +	tp->t_flags |= XFS_TRANS_RESERVE;
> +
> +	error = xfs_attr_args_init(&args, dp, name, flags);
> +	if (error)
> +		return error;
> +
> +	args.name = name;
> +	args.namelen = name_len;
> +	args.hashval = xfs_da_hashname(args.name, args.namelen);
> +	args.value = value;
> +	args.valuelen = value_len;
> +	args.dfops = &dfops;

dfops needs an xfs_defer_init().

Oh, the initialization of dfops is after where we start using it.
Please move it up (or the args.dfops assignment down).

> +	args.firstblock = &firstblock;
> +	args.op_flags = XFS_DA_OP_OKNOENT;
> +	args.total = xfs_attr_calc_size(&args, &local);
> +	args.trans = tp;
> +	ASSERT(local);
> +
> +	xfs_ilock(dp, XFS_ILOCK_EXCL);
> +	xfs_defer_init(args.dfops, args.firstblock);
> +
> +	if (op_flags & ATTR_OP_FLAGS_SET) {

switch (op_flags & XFS_ATTR_OP_FLAGS_TYPE_MASK) {
case XFS_ATTR_OP_FLAGS_SET:
	...
case XFS_ATTR_OP_FLAGS_REMOVE:
	...
default:
	...
}

> +		args.op_flags |= XFS_DA_OP_ADDNAME;
> +		error = xfs_attr_set_args(&args, flags, false);
> +	} else if (op_flags & ATTR_OP_FLAGS_REMOVE) {
> +		error = xfs_attr_remove_args(&args, flags);
> +	} else {
> +		ASSERT(0);

We're reading and processing log items off the disk, so cleaning up and
returning -EFSCORRUPTED is more appropriate here.

> +	}
> +
> +	if (error)
> +		xfs_defer_cancel(&dfops);
> +
> +	xfs_iunlock(dp, XFS_ILOCK_EXCL);
> +
> +	/*
> +	 * Mark the transaction dirty, even on error. This ensures the
> +	 * transaction is aborted, which:
> +	 *
> +	 * 1.) releases the ATTRI and frees the ATTRD
> +	 * 2.) shuts down the filesystem
> +	 */
> +	tp->t_flags |= XFS_TRANS_DIRTY;
> +	attrdp->item.li_desc->lid_flags |= XFS_LID_DIRTY;
> +
> +	next_attr = attrdp->next_attr;
> +	attrp = &(attrdp->format);
> +	attrp->ino = ino;
> +	attrp->op_flags = op_flags;
> +	attrp->value_len = value_len;
> +	attrp->name_len = name_len;
> +	attrp->attr_flags = flags;
> +
> +	attrdp->name = name;
> +	attrdp->value = value;
> +	attrdp->name_len = name_len;
> +	attrdp->value_len = value_len;
> +	attrdp->next_attr++;
> +
> +	return error;
> +}
> +
> +static int
> +xfs_attr_diff_items(
> +	void				*priv,
> +	struct list_head		*a,
> +	struct list_head		*b)
> +{
> +	return 0;
> +}
> +
> +/* Get an ATTRI. */
> +STATIC void *
> +xfs_attr_create_intent(
> +	struct xfs_trans		*tp,
> +	unsigned int			count)
> +{
> +	struct xfs_attri_log_item		*attrip;
> +
> +	ASSERT(tp != NULL);
> +	ASSERT(count > 0);
> +
> +	attrip = xfs_attri_init(tp->t_mountp);
> +	ASSERT(attrip != NULL);
> +
> +	/*
> +	 * Get a log_item_desc to point at the new item.
> +	 */
> +	xfs_trans_add_item(tp, &attrip->item);
> +	return attrip;
> +}
> +
> +/* Log an attr to the intent item. */
> +STATIC void
> +xfs_attr_log_item(
> +	struct xfs_trans		*tp,
> +	void				*intent,
> +	struct list_head		*item)
> +{
> +	struct xfs_attri_log_item	*attrip = intent;
> +	struct xfs_attr_item		*free;
> +	struct xfs_attr_log_format	*attrp;
> +
> +	free = container_of(item, struct xfs_attr_item, xattri_list);
> +
> +	tp->t_flags |= XFS_TRANS_DIRTY;
> +	attrip->item.li_desc->lid_flags |= XFS_LID_DIRTY;
> +
> +	attrp = &attrip->format;
> +	attrp->ino = free->xattri_ino;
> +	attrp->op_flags = free->xattri_op_flags;
> +	attrp->value_len = free->xattri_value_len;
> +	attrp->name_len = free->xattri_name_len;
> +	attrp->attr_flags = free->xattri_flags;
> +
> +	attrip->name = &(free->xattri_name[0]);
> +	attrip->value = &(free->xattri_value[0]);
> +	attrip->name_len = free->xattri_name_len;
> +	attrip->value_len = free->xattri_value_len;
> +}
> +
> +/* Get an ATTRD so we can process all the attrs. */
> +STATIC void *
> +xfs_attr_create_done(
> +	struct xfs_trans		*tp,
> +	void				*intent,
> +	unsigned int			count)
> +{
> +	return xfs_trans_get_attrd(tp, intent);
> +}
> +
> +/* Process an attr. */
> +STATIC int
> +xfs_attr_finish_item(
> +	struct xfs_trans		*tp,
> +	struct xfs_defer_ops		*dop,
> +	struct list_head		*item,
> +	void				*done_item,
> +	void				**state)
> +{
> +	struct xfs_attr_item	*free;
> +	int				error;
> +
> +	free = container_of(item, struct xfs_attr_item, xattri_list);
> +	error = xfs_trans_attr(tp, done_item,
> +			free->xattri_ino,
> +			free->xattri_op_flags,
> +			free->xattri_flags,
> +			free->xattri_name_len,
> +			free->xattri_value_len,
> +			free->xattri_name,
> +			free->xattri_value);
> +	kmem_free(free);
> +	return error;
> +}
> +
> +/* Abort all pending EFIs. */

EFIs?

--D

> +STATIC void
> +xfs_attr_abort_intent(
> +	void				*intent)
> +{
> +	xfs_attri_release(intent);
> +}
> +
> +/* Cancel an attr */
> +STATIC void
> +xfs_attr_cancel_item(
> +	struct list_head		*item)
> +{
> +	struct xfs_attr_item	*free;
> +
> +	free = container_of(item, struct xfs_attr_item, xattri_list);
> +	kmem_free(free);
> +}
> +
> +static const struct xfs_defer_op_type xfs_attr_defer_type = {
> +	.type		= XFS_DEFER_OPS_TYPE_ATTR,
> +	.max_items	= XFS_ATTRI_MAX_FAST_ATTRS,
> +	.diff_items	= xfs_attr_diff_items,
> +	.create_intent	= xfs_attr_create_intent,
> +	.abort_intent	= xfs_attr_abort_intent,
> +	.log_item	= xfs_attr_log_item,
> +	.create_done	= xfs_attr_create_done,
> +	.finish_item	= xfs_attr_finish_item,
> +	.cancel_item	= xfs_attr_cancel_item,
> +};
> +
> +/* Register the deferred op type. */
> +void
> +xfs_attr_init_defer_op(void)
> +{
> +	xfs_defer_init_op_type(&xfs_attr_defer_type);
> +}
> -- 
> 2.7.4
> 
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