Re: [PATCH v22 09/16] xfs: Implement attr logging and replay

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jul 26, 2021 at 11:20:46PM -0700, Allison Henderson wrote:
> This patch adds the needed routines to create, log and recover logged
> extended attribute intents.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_defer.c  |   1 +
>  fs/xfs/libxfs/xfs_defer.h  |   1 +
>  fs/xfs/libxfs/xfs_format.h |  10 +-
>  fs/xfs/xfs_attr_item.c     | 377 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 388 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
> index eff4a12..e9caff7 100644
> --- a/fs/xfs/libxfs/xfs_defer.c
> +++ b/fs/xfs/libxfs/xfs_defer.c
> @@ -178,6 +178,7 @@ static const struct xfs_defer_op_type *defer_op_types[] = {
>  	[XFS_DEFER_OPS_TYPE_RMAP]	= &xfs_rmap_update_defer_type,
>  	[XFS_DEFER_OPS_TYPE_FREE]	= &xfs_extent_free_defer_type,
>  	[XFS_DEFER_OPS_TYPE_AGFL_FREE]	= &xfs_agfl_free_defer_type,
> +	[XFS_DEFER_OPS_TYPE_ATTR]	= &xfs_attr_defer_type,
>  };
>  
>  static void
> diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
> index 0ed9dfa..72a5789 100644
> --- a/fs/xfs/libxfs/xfs_defer.h
> +++ b/fs/xfs/libxfs/xfs_defer.h
> @@ -19,6 +19,7 @@ enum xfs_defer_ops_type {
>  	XFS_DEFER_OPS_TYPE_RMAP,
>  	XFS_DEFER_OPS_TYPE_FREE,
>  	XFS_DEFER_OPS_TYPE_AGFL_FREE,
> +	XFS_DEFER_OPS_TYPE_ATTR,
>  	XFS_DEFER_OPS_TYPE_MAX,
>  };
>  
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index 3a4da111..93c1263 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -485,7 +485,9 @@ xfs_sb_has_incompat_feature(
>  	return (sbp->sb_features_incompat & feature) != 0;
>  }
>  
> -#define XFS_SB_FEAT_INCOMPAT_LOG_ALL 0
> +#define XFS_SB_FEAT_INCOMPAT_LOG_DELATTR   (1 << 0)	/* Delayed Attributes */

Echoing the conversation going on in IRC, can we change the name of this
feature bit/flag/function?  What we're really describing here is using
log-intent-based extended attribute updates.

IOWS, how about XFS_SB_FEAT_INCOMPAT_LOG_XATTRS?

> +#define XFS_SB_FEAT_INCOMPAT_LOG_ALL \
> +	(XFS_SB_FEAT_INCOMPAT_LOG_DELATTR)
>  #define XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN	~XFS_SB_FEAT_INCOMPAT_LOG_ALL
>  static inline bool
>  xfs_sb_has_incompat_log_feature(
> @@ -590,6 +592,12 @@ static inline bool xfs_sb_version_hasbigtime(struct xfs_sb *sbp)
>  		(sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_BIGTIME);
>  }
>  
> +static inline bool xfs_sb_version_hasdelattr(struct xfs_sb *sbp)

sb_version_haslogxattrs?

> +{
> +	return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
> +		(sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_LOG_DELATTR);

sb_features_log_incompat, as Chandan pointed out.

> +}
> +
>  /*
>   * Inode btree block counter.  We record the number of inobt and finobt blocks
>   * in the AGI header so that we can skip the finobt walk at mount time when
> diff --git a/fs/xfs/xfs_attr_item.c b/fs/xfs/xfs_attr_item.c
> index a810c2a..44c44d9 100644
> --- a/fs/xfs/xfs_attr_item.c
> +++ b/fs/xfs/xfs_attr_item.c
> @@ -275,6 +275,182 @@ xfs_attrd_item_release(
>  	xfs_attrd_item_free(attrdp);
>  }
>  
> +/*
> + * Performs one step of an attribute update intent and marks the attrd item
> + * dirty..  An attr operation may be a set or a remove.  Note that the
> + * transaction is marked dirty regardless of whether the operation succeeds or
> + * fails to support the ATTRI/ATTRD lifecycle rules.
> + */
> +STATIC int
> +xfs_trans_attr_finish_update(
> +	struct xfs_delattr_context	*dac,
> +	struct xfs_attrd_log_item	*attrdp,
> +	struct xfs_buf			**leaf_bp,
> +	uint32_t			op_flags)
> +{
> +	struct xfs_da_args		*args = dac->da_args;
> +	unsigned int			op = op_flags &
> +					     XFS_ATTR_OP_FLAGS_TYPE_MASK;
> +	int				error;
> +
> +	error = xfs_qm_dqattach_locked(args->dp, 0);
> +	if (error)
> +		return error;

We already attached dquots in xlog_recover_iget, so you can remove this
entirely.

> +
> +	switch (op) {
> +	case XFS_ATTR_OP_FLAGS_SET:
> +		args->op_flags |= XFS_DA_OP_ADDNAME;
> +		error = xfs_attr_set_iter(dac, leaf_bp);
> +		break;
> +	case XFS_ATTR_OP_FLAGS_REMOVE:
> +		ASSERT(XFS_IFORK_Q(args->dp));
> +		error = xfs_attr_remove_iter(dac);
> +		break;
> +	default:
> +		error = -EFSCORRUPTED;
> +		break;
> +	}
> +
> +	/*
> +	 * 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
> +	 */
> +	args->trans->t_flags |= XFS_TRANS_DIRTY;
> +
> +	/*
> +	 * attr intent/done items are null when delayed attributes are disabled
> +	 */
> +	if (attrdp)
> +		set_bit(XFS_LI_DIRTY, &attrdp->attrd_item.li_flags);
> +
> +	return error;
> +}
> +
> +/* Log an attr to the intent item. */
> +STATIC void
> +xfs_attr_log_item(
> +	struct xfs_trans		*tp,
> +	struct xfs_attri_log_item	*attrip,
> +	struct xfs_attr_item		*attr)
> +{
> +	struct xfs_attri_log_format	*attrp;
> +
> +	tp->t_flags |= XFS_TRANS_DIRTY;
> +	set_bit(XFS_LI_DIRTY, &attrip->attri_item.li_flags);
> +
> +	/*
> +	 * At this point the xfs_attr_item has been constructed, and we've
> +	 * created the log intent. Fill in the attri log item and log format
> +	 * structure with fields from this xfs_attr_item
> +	 */
> +	attrp = &attrip->attri_format;
> +	attrp->alfi_ino = attr->xattri_dac.da_args->dp->i_ino;
> +	attrp->alfi_op_flags = attr->xattri_op_flags;
> +	attrp->alfi_value_len = attr->xattri_dac.da_args->valuelen;
> +	attrp->alfi_name_len = attr->xattri_dac.da_args->namelen;
> +	attrp->alfi_attr_flags = attr->xattri_dac.da_args->attr_filter;
> +
> +	attrip->attri_name = (void *)attr->xattri_dac.da_args->name;
> +	attrip->attri_value = attr->xattri_dac.da_args->value;
> +	attrip->attri_name_len = attr->xattri_dac.da_args->namelen;
> +	attrip->attri_value_len = attr->xattri_dac.da_args->valuelen;
> +}
> +
> +/* Get an ATTRI. */
> +static struct xfs_log_item *
> +xfs_attr_create_intent(
> +	struct xfs_trans		*tp,
> +	struct list_head		*items,
> +	unsigned int			count,
> +	bool				sort)
> +{
> +	struct xfs_mount		*mp = tp->t_mountp;
> +	struct xfs_attri_log_item	*attrip;
> +	struct xfs_attr_item		*attr;
> +
> +	ASSERT(count == 1);
> +
> +	if (!xfs_hasdelattr(mp))

At this point we should already have turned on the log incompat feature
bit if the sysadmin used the secret mount option, correct?  In that
case, I think this check should be

	if (!xfs_sb_version_haslogxattrs(&mp->m_sb))
		return NULL;

> +		return NULL;
> +
> +	attrip = xfs_attri_init(mp, 0);
> +	if (attrip == NULL)
> +		return NULL;
> +
> +	xfs_trans_add_item(tp, &attrip->attri_item);
> +	list_for_each_entry(attr, items, xattri_list)
> +		xfs_attr_log_item(tp, attrip, attr);
> +	return &attrip->attri_item;
> +}
> +
> +/* Process an attr. */
> +STATIC int
> +xfs_attr_finish_item(
> +	struct xfs_trans		*tp,
> +	struct xfs_log_item		*done,
> +	struct list_head		*item,
> +	struct xfs_btree_cur		**state)
> +{
> +	struct xfs_attr_item		*attr;
> +	struct xfs_attrd_log_item	*done_item = NULL;
> +	int				error;
> +	struct xfs_delattr_context	*dac;
> +
> +	attr = container_of(item, struct xfs_attr_item, xattri_list);
> +	dac = &attr->xattri_dac;
> +	if (done)
> +		done_item = ATTRD_ITEM(done);
> +
> +	/*
> +	 * Corner case that can happen during a recovery.  Because the first
> +	 * iteration of a multi part delay op happens in xfs_attri_item_recover
> +	 * to maintain the order of the log replay items.  But the new
> +	 * transactions do not automatically rejoin during a recovery as they do
> +	 * in a standard delay op, so we need to catch this here and rejoin the
> +	 * leaf to the new transaction
> +	 */
> +	if (attr->xattri_dac.leaf_bp &&
> +	    attr->xattri_dac.leaf_bp->b_transp != tp) {
> +		xfs_trans_bjoin(tp, attr->xattri_dac.leaf_bp);
> +		xfs_trans_bhold(tp, attr->xattri_dac.leaf_bp);
> +	}

This is subtle.  The attri recovery function makes a direct call to
xfs_trans_attr_finish_update before doing the capture-and-commit dance.
When the captured items get replayed (separately) the defer ops
mechanism calls this function, and that's the point at which we end up
here needing to join and hold the leaf_bp to the transaction.

Do we have a reference to leaf_bp at this point?  When we return from
xfs_trans_attr_finish_update in xfs_attri_item_recover, the leaf_bp (if
any) is joined and held to the transaction that is committed in the
"commit and capture".  Following the transaction commit I /think/ it's
the case that we still have a reference to the leaf_bp?

So we have a reference to the leaf_bp and eventually we need to join it
to the transaction that's used to continue the recovery.  What if the
capture and commit function detected buffers that are bheld to the
transaction and recorded them in the capture structure so that
xlog_finish_defer_ops could do this part for you?

> +
> +	/*
> +	 * Always reset trans after EAGAIN cycle
> +	 * since the transaction is new
> +	 */
> +	dac->da_args->trans = tp;
> +
> +	error = xfs_trans_attr_finish_update(dac, done_item, &dac->leaf_bp,
> +					     attr->xattri_op_flags);
> +	if (error != -EAGAIN)
> +		kmem_free(attr);
> +
> +	return error;
> +}
> +
> +/* Abort all pending ATTRs. */
> +STATIC void
> +xfs_attr_abort_intent(
> +	struct xfs_log_item		*intent)
> +{
> +	xfs_attri_release(ATTRI_ITEM(intent));
> +}
> +
> +/* Cancel an attr */
> +STATIC void
> +xfs_attr_cancel_item(
> +	struct list_head		*item)
> +{
> +	struct xfs_attr_item		*attr;
> +
> +	attr = container_of(item, struct xfs_attr_item, xattri_list);
> +	kmem_free(attr);
> +}
> +
>  STATIC xfs_lsn_t
>  xfs_attri_item_committed(
>  	struct xfs_log_item		*lip,
> @@ -306,6 +482,30 @@ xfs_attri_item_match(
>  	return ATTRI_ITEM(lip)->attri_format.alfi_id == intent_id;
>  }
>  
> +/*
> + * This routine is called to allocate an "attr free done" log item.
> + */
> +static 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;
> +	uint					size;
> +
> +	ASSERT(tp != NULL);
> +
> +	size = sizeof(struct xfs_attrd_log_item);
> +	attrdp = kmem_zalloc(size, 0);
> +
> +	xfs_log_item_init(tp->t_mountp, &attrdp->attrd_item, XFS_LI_ATTRD,
> +			  &xfs_attrd_item_ops);
> +	attrdp->attrd_attrip = attrip;
> +	attrdp->attrd_format.alfd_alf_id = attrip->attri_format.alfi_id;
> +
> +	xfs_trans_add_item(tp, &attrdp->attrd_item);
> +	return attrdp;
> +}
> +
>  static const struct xfs_item_ops xfs_attrd_item_ops = {
>  	.flags		= XFS_ITEM_RELEASE_WHEN_COMMITTED,
>  	.iop_size	= xfs_attrd_item_size,
> @@ -313,6 +513,29 @@ static const struct xfs_item_ops xfs_attrd_item_ops = {
>  	.iop_release    = xfs_attrd_item_release,
>  };
>  
> +
> +/* Get an ATTRD so we can process all the attrs. */
> +static struct xfs_log_item *
> +xfs_attr_create_done(
> +	struct xfs_trans		*tp,
> +	struct xfs_log_item		*intent,
> +	unsigned int			count)
> +{
> +	if (!intent)
> +		return NULL;
> +
> +	return &xfs_trans_get_attrd(tp, ATTRI_ITEM(intent))->attrd_item;
> +}
> +
> +const struct xfs_defer_op_type xfs_attr_defer_type = {
> +	.max_items	= 1,
> +	.create_intent	= xfs_attr_create_intent,
> +	.abort_intent	= xfs_attr_abort_intent,
> +	.create_done	= xfs_attr_create_done,
> +	.finish_item	= xfs_attr_finish_item,
> +	.cancel_item	= xfs_attr_cancel_item,
> +};
> +
>  /* Is this recovered ATTRI ok? */
>  static inline bool
>  xfs_attri_validate(
> @@ -340,13 +563,167 @@ xfs_attri_validate(
>  	return xfs_hasdelattr(mp);
>  }
>  
> +/*
> + * Process an attr intent item that was recovered from the log.  We need to
> + * delete the attr that it describes.
> + */
> +STATIC int
> +xfs_attri_item_recover(
> +	struct xfs_log_item		*lip,
> +	struct list_head		*capture_list)
> +{
> +	struct xfs_attri_log_item	*attrip = ATTRI_ITEM(lip);
> +	struct xfs_attr_item		*attr;
> +	struct xfs_mount		*mp = lip->li_mountp;
> +	struct xfs_inode		*ip;
> +	struct xfs_da_args		*args;
> +	struct xfs_trans		*tp;
> +	struct xfs_trans_res		tres;
> +	struct xfs_attri_log_format	*attrp;
> +	int				error, ret = 0;
> +	int				total;
> +	int				local;
> +	struct xfs_attrd_log_item	*done_item = NULL;
> +
> +	/*
> +	 * 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->attri_format;
> +	if (!xfs_attri_validate(mp, attrip))
> +		return -EFSCORRUPTED;
> +
> +	error = xlog_recover_iget(mp,  attrp->alfi_ino, &ip);
> +	if (error)
> +		return error;
> +
> +	attr = kmem_zalloc(sizeof(struct xfs_attr_item) +
> +			   sizeof(struct xfs_da_args), KM_NOFS);
> +	args = (struct xfs_da_args *)((char *)attr +
> +		   sizeof(struct xfs_attr_item));

	args = (struct xfs_da_args *)(attr + 1); ?

--D

> +
> +	attr->xattri_dac.da_args = args;
> +	attr->xattri_op_flags = attrp->alfi_op_flags;
> +
> +	args->dp = ip;
> +	args->geo = mp->m_attr_geo;
> +	args->op_flags = attrp->alfi_op_flags;
> +	args->whichfork = XFS_ATTR_FORK;
> +	args->name = attrip->attri_name;
> +	args->namelen = attrp->alfi_name_len;
> +	args->hashval = xfs_da_hashname(args->name, args->namelen);
> +	args->attr_filter = attrp->alfi_attr_flags;
> +
> +	if (attrp->alfi_op_flags == XFS_ATTR_OP_FLAGS_SET) {
> +		args->value = attrip->attri_value;
> +		args->valuelen = attrp->alfi_value_len;
> +		args->total = xfs_attr_calc_size(args, &local);
> +
> +		tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
> +				 M_RES(mp)->tr_attrsetrt.tr_logres *
> +					args->total;
> +		tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
> +		tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
> +		total = args->total;
> +	} else {
> +		tres = M_RES(mp)->tr_attrrm;
> +		total = XFS_ATTRRM_SPACE_RES(mp);
> +	}
> +	error = xfs_trans_alloc(mp, &tres, total, 0, XFS_TRANS_RESERVE, &tp);
> +	if (error)
> +		goto out;
> +
> +	args->trans = tp;
> +	done_item = xfs_trans_get_attrd(tp, attrip);
> +
> +	xfs_ilock(ip, XFS_ILOCK_EXCL);
> +	xfs_trans_ijoin(tp, ip, 0);
> +
> +	ret = xfs_trans_attr_finish_update(&attr->xattri_dac, done_item,
> +					   &attr->xattri_dac.leaf_bp,
> +					   attrp->alfi_op_flags);
> +	if (ret == -EAGAIN) {
> +		/* There's more work to do, so add it to this transaction */
> +		xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_ATTR, &attr->xattri_list);
> +	} else
> +		error = ret;
> +
> +	if (error) {
> +		xfs_trans_cancel(tp);
> +		goto out_unlock;
> +	}
> +
> +	error = xfs_defer_ops_capture_and_commit(tp, ip, capture_list);
> +
> +out_unlock:
> +	xfs_iunlock(ip, XFS_ILOCK_EXCL);
> +	xfs_irele(ip);
> +out:
> +	if (ret != -EAGAIN)
> +		kmem_free(attr);
> +	return error;
> +}
> +
> +/* Re-log an intent item to push the log tail forward. */
> +static struct xfs_log_item *
> +xfs_attri_item_relog(
> +	struct xfs_log_item		*intent,
> +	struct xfs_trans		*tp)
> +{
> +	struct xfs_attrd_log_item	*attrdp;
> +	struct xfs_attri_log_item	*old_attrip;
> +	struct xfs_attri_log_item	*new_attrip;
> +	struct xfs_attri_log_format	*new_attrp;
> +	struct xfs_attri_log_format	*old_attrp;
> +	int				buffer_size;
> +
> +	old_attrip = ATTRI_ITEM(intent);
> +	old_attrp = &old_attrip->attri_format;
> +	buffer_size = old_attrp->alfi_value_len + old_attrp->alfi_name_len;
> +
> +	tp->t_flags |= XFS_TRANS_DIRTY;
> +	attrdp = xfs_trans_get_attrd(tp, old_attrip);
> +	set_bit(XFS_LI_DIRTY, &attrdp->attrd_item.li_flags);
> +
> +	new_attrip = xfs_attri_init(tp->t_mountp, buffer_size);
> +	new_attrp = &new_attrip->attri_format;
> +
> +	new_attrp->alfi_ino = old_attrp->alfi_ino;
> +	new_attrp->alfi_op_flags = old_attrp->alfi_op_flags;
> +	new_attrp->alfi_value_len = old_attrp->alfi_value_len;
> +	new_attrp->alfi_name_len = old_attrp->alfi_name_len;
> +	new_attrp->alfi_attr_flags = old_attrp->alfi_attr_flags;
> +
> +	new_attrip->attri_name_len = old_attrip->attri_name_len;
> +	new_attrip->attri_name = ((char *)new_attrip) +
> +				 sizeof(struct xfs_attri_log_item);
> +	memcpy(new_attrip->attri_name, old_attrip->attri_name,
> +		new_attrip->attri_name_len);
> +
> +	new_attrip->attri_value_len = old_attrip->attri_value_len;
> +	if (new_attrip->attri_value_len > 0) {
> +		new_attrip->attri_value = new_attrip->attri_name +
> +					  new_attrip->attri_name_len;
> +
> +		memcpy(new_attrip->attri_value, old_attrip->attri_value,
> +		       new_attrip->attri_value_len);
> +	}
> +
> +	xfs_trans_add_item(tp, &new_attrip->attri_item);
> +	set_bit(XFS_LI_DIRTY, &new_attrip->attri_item.li_flags);
> +
> +	return &new_attrip->attri_item;
> +}
> +
>  static const struct xfs_item_ops xfs_attri_item_ops = {
>  	.iop_size	= xfs_attri_item_size,
>  	.iop_format	= xfs_attri_item_format,
>  	.iop_unpin	= xfs_attri_item_unpin,
>  	.iop_committed	= xfs_attri_item_committed,
>  	.iop_release    = xfs_attri_item_release,
> +	.iop_recover	= xfs_attri_item_recover,
>  	.iop_match	= xfs_attri_item_match,
> +	.iop_relog	= xfs_attri_item_relog,
>  };
>  
>  
> -- 
> 2.7.4
>