fs/xfs/xfs_filestream.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2006-2007 Silicon Graphics, Inc.
  * Copyright (c) 2014 Christoph Hellwig.
  * All Rights Reserved.
  */
 #include "xfs.h"
 #include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
 #include "xfs_inode.h"
 #include "xfs_bmap.h"
 #include "xfs_bmap_util.h"
 #include "xfs_alloc.h"
 #include "xfs_mru_cache.h"
 #include "xfs_trace.h"
 #include "xfs_ag.h"
 #include "xfs_ag_resv.h"
 #include "xfs_trans.h"
 #include "xfs_filestream.h"

 struct xfs_fstrm_item {
 	struct xfs_mru_cache_elem	mru;
 	struct xfs_perag		*pag; /* AG in use for this directory */
 };

 enum xfs_fstrm_alloc {
 	XFS_PICK_USERDATA = 1,
 	XFS_PICK_LOWSPACE = 2,
 };

 static void
 xfs_fstrm_free_func(
 	void			*data,
 	struct xfs_mru_cache_elem *mru)
 {
 	struct xfs_fstrm_item	*item =
 		container_of(mru, struct xfs_fstrm_item, mru);
 	struct xfs_perag	*pag = item->pag;

 	trace_xfs_filestream_free(pag, mru->key);
 	atomic_dec(&pag->pagf_fstrms);
 	xfs_perag_rele(pag);

 	kfree(item);
 }

 /*
  * Scan the AGs starting at start_agno looking for an AG that isn't in use and
  * has at least minlen blocks free. If no AG is found to match the allocation
  * requirements, pick the AG with the most free space in it.
  */
 static int
 xfs_filestream_pick_ag(
 	struct xfs_alloc_arg	*args,
 	xfs_ino_t		pino,
 	xfs_agnumber_t		start_agno,
 	int			flags,
 	xfs_extlen_t		*longest)
 {
 	struct xfs_mount	*mp = args->mp;
 	struct xfs_perag	*pag;
 	struct xfs_perag	*max_pag = NULL;
 	xfs_extlen_t		minlen = *longest;
 	xfs_extlen_t		minfree, maxfree = 0;
 	xfs_agnumber_t		agno;
 	bool			first_pass = true;

 	/* 2% of an AG's blocks must be free for it to be chosen. */
 	minfree = mp->m_sb.sb_agblocks / 50;

 restart:
 	for_each_perag_wrap(mp, start_agno, agno, pag) {
 		int		err;

 		trace_xfs_filestream_scan(pag, pino);

 		*longest = 0;
 		err = xfs_bmap_longest_free_extent(pag, NULL, longest);
 		if (err) {
 			if (err == -EAGAIN) {
 				/* Couldn't lock the AGF, skip this AG. */
 				err = 0;
 				continue;
 			}
 			xfs_perag_rele(pag);
 			if (max_pag)
 				xfs_perag_rele(max_pag);
 			return err;
 		}

 		/* Keep track of the AG with the most free blocks. */
 		if (pag->pagf_freeblks > maxfree) {
 			maxfree = pag->pagf_freeblks;
 			if (max_pag)
 				xfs_perag_rele(max_pag);
 			atomic_inc(&pag_group(pag)->xg_active_ref);
 			max_pag = pag;
 		}

 		/*
 		 * The AG reference count does two things: it enforces mutual
 		 * exclusion when examining the suitability of an AG in this
 		 * loop, and it guards against two filestreams being established
 		 * in the same AG as each other.
 		 */
 		if (atomic_inc_return(&pag->pagf_fstrms) <= 1) {
 			if (((minlen && *longest >= minlen) ||
 			     (!minlen && pag->pagf_freeblks >= minfree)) &&
 			    (!xfs_perag_prefers_metadata(pag) ||
 			     !(flags & XFS_PICK_USERDATA) ||
 			     (flags & XFS_PICK_LOWSPACE))) {
 				/* Break out, retaining the reference on the AG. */
 				if (max_pag)
 					xfs_perag_rele(max_pag);
 				goto done;
 			}
 		}

 		/* Drop the reference on this AG, it's not usable. */
 		atomic_dec(&pag->pagf_fstrms);
 	}

 	/*
 	 * Allow a second pass to give xfs_bmap_longest_free_extent() another
 	 * attempt at locking AGFs that it might have skipped over before we
 	 * fail.
 	 */
 	if (first_pass) {
 		first_pass = false;
 		goto restart;
 	}

 	/*
 	 * We must be low on data space, so run a final lowspace optimised
 	 * selection pass if we haven't already.
 	 */
 	if (!(flags & XFS_PICK_LOWSPACE)) {
 		flags |= XFS_PICK_LOWSPACE;
 		goto restart;
 	}

 	/*
 	 * No unassociated AGs are available, so select the AG with the most
 	 * free space, regardless of whether it's already in use by another
 	 * filestream. It none suit, just use whatever AG we can grab.
 	 */
 	if (!max_pag) {
 		for_each_perag_wrap(args->mp, 0, start_agno, pag) {
 			max_pag = pag;
 			break;
 		}

 		/* Bail if there are no AGs at all to select from. */
 		if (!max_pag)
 			return -ENOSPC;
 	}

 	pag = max_pag;
 	atomic_inc(&pag->pagf_fstrms);
 done:
 	trace_xfs_filestream_pick(pag, pino);
 	args->pag = pag;
 	return 0;
 }

 static struct xfs_inode *
 xfs_filestream_get_parent(
 	struct xfs_inode	*ip)
 {
 	struct inode		*inode = VFS_I(ip), *dir = NULL;
 	struct dentry		*dentry, *parent;

 	dentry = d_find_alias(inode);
 	if (!dentry)
 		goto out;

 	parent = dget_parent(dentry);
 	if (!parent)
 		goto out_dput;

 	dir = igrab(d_inode(parent));
 	dput(parent);

 out_dput:
 	dput(dentry);
 out:
 	return dir ? XFS_I(dir) : NULL;
 }

 /*
  * Lookup the mru cache for an existing association. If one exists and we can
  * use it, return with an active perag reference indicating that the allocation
  * will proceed with that association.
  *
  * If we have no association, or we cannot use the current one and have to
  * destroy it, return with longest = 0 to tell the caller to create a new
  * association.
  */
 static int
 xfs_filestream_lookup_association(
 	struct xfs_bmalloca	*ap,
 	struct xfs_alloc_arg	*args,
 	xfs_ino_t		pino,
 	xfs_extlen_t		*longest)
 {
 	struct xfs_mount	*mp = args->mp;
 	struct xfs_perag	*pag;
 	struct xfs_mru_cache_elem *mru;
 	int			error = 0;

 	*longest = 0;
 	mru = xfs_mru_cache_lookup(mp->m_filestream, pino);
 	if (!mru)
 		return 0;
 	/*
 	 * Grab the pag and take an extra active reference for the caller whilst
 	 * the mru item cannot go away. This means we'll pin the perag with
 	 * the reference we get here even if the filestreams association is torn
 	 * down immediately after we mark the lookup as done.
 	 */
 	pag = container_of(mru, struct xfs_fstrm_item, mru)->pag;
 	atomic_inc(&pag_group(pag)->xg_active_ref);
 	xfs_mru_cache_done(mp->m_filestream);

 	trace_xfs_filestream_lookup(pag, ap->ip->i_ino);

 	ap->blkno = xfs_agbno_to_fsb(pag, 0);
 	xfs_bmap_adjacent(ap);

 	/*
 	 * If there is very little free space before we start a filestreams
 	 * allocation, we're almost guaranteed to fail to find a large enough
 	 * free space available so just use the cached AG.
 	 */
 	if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
 		*longest = 1;
 		goto out_done;
 	}

 	error = xfs_bmap_longest_free_extent(pag, args->tp, longest);
 	if (error == -EAGAIN)
 		error = 0;
 	if (error || *longest < args->maxlen) {
 		/* We aren't going to use this perag */
 		*longest = 0;
 		xfs_perag_rele(pag);
 		return error;
 	}

 out_done:
 	args->pag = pag;
 	return 0;
 }

 static int
 xfs_filestream_create_association(
 	struct xfs_bmalloca	*ap,
 	struct xfs_alloc_arg	*args,
 	xfs_ino_t		pino,
 	xfs_extlen_t		*longest)
 {
 	struct xfs_mount	*mp = args->mp;
 	struct xfs_mru_cache_elem *mru;
 	struct xfs_fstrm_item	*item;
 	xfs_agnumber_t		agno = XFS_INO_TO_AGNO(mp, pino);
 	int			flags = 0;
 	int			error;

 	/* Changing parent AG association now, so remove the existing one. */
 	mru = xfs_mru_cache_remove(mp->m_filestream, pino);
 	if (mru) {
 		struct xfs_fstrm_item *item =
 			container_of(mru, struct xfs_fstrm_item, mru);

 		agno = (pag_agno(item->pag) + 1) % mp->m_sb.sb_agcount;
 		xfs_fstrm_free_func(mp, mru);
 	} else if (xfs_is_inode32(mp)) {
 		xfs_agnumber_t	 rotorstep = xfs_rotorstep;

 		agno = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount;
 		mp->m_agfrotor = (mp->m_agfrotor + 1) %
 				 (mp->m_sb.sb_agcount * rotorstep);
 	}

 	ap->blkno = XFS_AGB_TO_FSB(args->mp, agno, 0);
 	xfs_bmap_adjacent(ap);

 	if (ap->datatype & XFS_ALLOC_USERDATA)
 		flags |= XFS_PICK_USERDATA;
 	if (ap->tp->t_flags & XFS_TRANS_LOWMODE)
 		flags |= XFS_PICK_LOWSPACE;

 	*longest = ap->length;
 	error = xfs_filestream_pick_ag(args, pino, agno, flags, longest);
 	if (error)
 		return error;

 	/*
 	 * We are going to use this perag now, so create an assoication for it.
 	 * xfs_filestream_pick_ag() has already bumped the perag fstrms counter
 	 * for us, so all we need to do here is take another active reference to
 	 * the perag for the cached association.
 	 *
 	 * If we fail to store the association, we need to drop the fstrms
 	 * counter as well as drop the perag reference we take here for the
 	 * item. We do not need to return an error for this failure - as long as
 	 * we return a referenced AG, the allocation can still go ahead just
 	 * fine.
 	 */
 	item = kmalloc(sizeof(*item), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 	if (!item)
 		goto out_put_fstrms;

 	atomic_inc(&pag_group(args->pag)->xg_active_ref);
 	item->pag = args->pag;
 	error = xfs_mru_cache_insert(mp->m_filestream, pino, &item->mru);
 	if (error)
 		goto out_free_item;
 	return 0;

 out_free_item:
 	xfs_perag_rele(item->pag);
 	kfree(item);
 out_put_fstrms:
 	atomic_dec(&args->pag->pagf_fstrms);
 	return 0;
 }

 /*
  * Search for an allocation group with a single extent large enough for
  * the request. First we look for an existing association and use that if it
  * is found. Otherwise, we create a new association by selecting an AG that fits
  * the allocation criteria.
  *
  * We return with a referenced perag in args->pag to indicate which AG we are
  * allocating into or an error with no references held.
  */
 int
 xfs_filestream_select_ag(
 	struct xfs_bmalloca	*ap,
 	struct xfs_alloc_arg	*args,
 	xfs_extlen_t		*longest)
 {
 	struct xfs_inode	*pip;
 	xfs_ino_t		ino = 0;
 	int			error = 0;

 	*longest = 0;
 	args->total = ap->total;
 	pip = xfs_filestream_get_parent(ap->ip);
 	if (pip) {
 		ino = pip->i_ino;
 		error = xfs_filestream_lookup_association(ap, args, ino,
 				longest);
 		xfs_irele(pip);
 		if (error)
 			return error;
 		if (*longest >= args->maxlen)
 			goto out_select;
 		if (ap->tp->t_flags & XFS_TRANS_LOWMODE)
 			goto out_select;
 	}

 	error = xfs_filestream_create_association(ap, args, ino, longest);
 	if (error)
 		return error;

 out_select:
 	ap->blkno = xfs_agbno_to_fsb(args->pag, 0);
 	return 0;
 }

 void
 xfs_filestream_deassociate(
 	struct xfs_inode	*ip)
 {
 	xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino);
 }

 int
 xfs_filestream_mount(
 	xfs_mount_t	*mp)
 {
 	/*
 	 * The filestream timer tunable is currently fixed within the range of
 	 * one second to four minutes, with five seconds being the default.  The
 	 * group count is somewhat arbitrary, but it'd be nice to adhere to the
 	 * timer tunable to within about 10 percent.  This requires at least 10
 	 * groups.
 	 */
 	return xfs_mru_cache_create(&mp->m_filestream, mp,
 			xfs_fstrm_centisecs * 10, 10, xfs_fstrm_free_func);
 }

 void
 xfs_filestream_unmount(
 	xfs_mount_t	*mp)
 {
 	xfs_mru_cache_destroy(mp->m_filestream);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (c) 2006-2007 Silicon Graphics, Inc.
	* Copyright (c) 2014 Christoph Hellwig.
	* All Rights Reserved.
	*/
	#include "xfs.h"
	#include "xfs_shared.h"
	#include "xfs_format.h"
	#include "xfs_log_format.h"
	#include "xfs_trans_resv.h"
	#include "xfs_mount.h"
	#include "xfs_inode.h"
	#include "xfs_bmap.h"
	#include "xfs_bmap_util.h"
	#include "xfs_alloc.h"
	#include "xfs_mru_cache.h"
	#include "xfs_trace.h"
	#include "xfs_ag.h"
	#include "xfs_ag_resv.h"
	#include "xfs_trans.h"
	#include "xfs_filestream.h"

	struct xfs_fstrm_item {
	struct xfs_mru_cache_elem mru;
	struct xfs_perag pag; / AG in use for this directory */
	};

	enum xfs_fstrm_alloc {
	XFS_PICK_USERDATA = 1,
	XFS_PICK_LOWSPACE = 2,
	};

	static void
	xfs_fstrm_free_func(
	void *data,
	struct xfs_mru_cache_elem *mru)
	{
	struct xfs_fstrm_item *item =
	container_of(mru, struct xfs_fstrm_item, mru);
	struct xfs_perag *pag = item->pag;

	trace_xfs_filestream_free(pag, mru->key);
	atomic_dec(&pag->pagf_fstrms);
	xfs_perag_rele(pag);

	kfree(item);
	}

	/*
	* Scan the AGs starting at start_agno looking for an AG that isn't in use and
	* has at least minlen blocks free. If no AG is found to match the allocation
	* requirements, pick the AG with the most free space in it.
	*/
	static int
	xfs_filestream_pick_ag(
	struct xfs_alloc_arg *args,
	xfs_ino_t pino,
	xfs_agnumber_t start_agno,
	int flags,
	xfs_extlen_t *longest)
	{
	struct xfs_mount *mp = args->mp;
	struct xfs_perag *pag;
	struct xfs_perag *max_pag = NULL;
	xfs_extlen_t minlen = *longest;
	xfs_extlen_t minfree, maxfree = 0;
	xfs_agnumber_t agno;
	bool first_pass = true;

	/* 2% of an AG's blocks must be free for it to be chosen. */
	minfree = mp->m_sb.sb_agblocks / 50;

	restart:
	for_each_perag_wrap(mp, start_agno, agno, pag) {
	int err;

	trace_xfs_filestream_scan(pag, pino);

	*longest = 0;
	err = xfs_bmap_longest_free_extent(pag, NULL, longest);
	if (err) {
	if (err == -EAGAIN) {
	/* Couldn't lock the AGF, skip this AG. */
	err = 0;
	continue;
	}
	xfs_perag_rele(pag);
	if (max_pag)
	xfs_perag_rele(max_pag);
	return err;
	}

	/* Keep track of the AG with the most free blocks. */
	if (pag->pagf_freeblks > maxfree) {
	maxfree = pag->pagf_freeblks;
	if (max_pag)
	xfs_perag_rele(max_pag);
	atomic_inc(&pag_group(pag)->xg_active_ref);
	max_pag = pag;
	}

	/*
	* The AG reference count does two things: it enforces mutual
	* exclusion when examining the suitability of an AG in this
	* loop, and it guards against two filestreams being established
	* in the same AG as each other.
	*/
	if (atomic_inc_return(&pag->pagf_fstrms) <= 1) {
	if (((minlen && *longest >= minlen) \|\|
	(!minlen && pag->pagf_freeblks >= minfree)) &&
	(!xfs_perag_prefers_metadata(pag) \|\|
	!(flags & XFS_PICK_USERDATA) \|\|
	(flags & XFS_PICK_LOWSPACE))) {
	/* Break out, retaining the reference on the AG. */
	if (max_pag)
	xfs_perag_rele(max_pag);
	goto done;
	}
	}

	/* Drop the reference on this AG, it's not usable. */
	atomic_dec(&pag->pagf_fstrms);
	}

	/*
	* Allow a second pass to give xfs_bmap_longest_free_extent() another
	* attempt at locking AGFs that it might have skipped over before we
	* fail.
	*/
	if (first_pass) {
	first_pass = false;
	goto restart;
	}

	/*
	* We must be low on data space, so run a final lowspace optimised
	* selection pass if we haven't already.
	*/
	if (!(flags & XFS_PICK_LOWSPACE)) {
	flags \|= XFS_PICK_LOWSPACE;
	goto restart;
	}

	/*
	* No unassociated AGs are available, so select the AG with the most
	* free space, regardless of whether it's already in use by another
	* filestream. It none suit, just use whatever AG we can grab.
	*/
	if (!max_pag) {
	for_each_perag_wrap(args->mp, 0, start_agno, pag) {
	max_pag = pag;
	break;
	}

	/* Bail if there are no AGs at all to select from. */
	if (!max_pag)
	return -ENOSPC;
	}

	pag = max_pag;
	atomic_inc(&pag->pagf_fstrms);
	done:
	trace_xfs_filestream_pick(pag, pino);
	args->pag = pag;
	return 0;
	}

	static struct xfs_inode *
	xfs_filestream_get_parent(
	struct xfs_inode *ip)
	{
	struct inode inode = VFS_I(ip), dir = NULL;
	struct dentry dentry, parent;

	dentry = d_find_alias(inode);
	if (!dentry)
	goto out;

	parent = dget_parent(dentry);
	if (!parent)
	goto out_dput;

	dir = igrab(d_inode(parent));
	dput(parent);

	out_dput:
	dput(dentry);
	out:
	return dir ? XFS_I(dir) : NULL;
	}

	/*
	* Lookup the mru cache for an existing association. If one exists and we can
	* use it, return with an active perag reference indicating that the allocation
	* will proceed with that association.
	*
	* If we have no association, or we cannot use the current one and have to
	* destroy it, return with longest = 0 to tell the caller to create a new
	* association.
	*/
	static int
	xfs_filestream_lookup_association(
	struct xfs_bmalloca *ap,
	struct xfs_alloc_arg *args,
	xfs_ino_t pino,
	xfs_extlen_t *longest)
	{
	struct xfs_mount *mp = args->mp;
	struct xfs_perag *pag;
	struct xfs_mru_cache_elem *mru;
	int error = 0;

	*longest = 0;
	mru = xfs_mru_cache_lookup(mp->m_filestream, pino);
	if (!mru)
	return 0;
	/*
	* Grab the pag and take an extra active reference for the caller whilst
	* the mru item cannot go away. This means we'll pin the perag with
	* the reference we get here even if the filestreams association is torn
	* down immediately after we mark the lookup as done.
	*/
	pag = container_of(mru, struct xfs_fstrm_item, mru)->pag;
	atomic_inc(&pag_group(pag)->xg_active_ref);
	xfs_mru_cache_done(mp->m_filestream);

	trace_xfs_filestream_lookup(pag, ap->ip->i_ino);

	ap->blkno = xfs_agbno_to_fsb(pag, 0);
	xfs_bmap_adjacent(ap);

	/*
	* If there is very little free space before we start a filestreams
	* allocation, we're almost guaranteed to fail to find a large enough
	* free space available so just use the cached AG.
	*/
	if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
	*longest = 1;
	goto out_done;
	}

	error = xfs_bmap_longest_free_extent(pag, args->tp, longest);
	if (error == -EAGAIN)
	error = 0;
	if (error \|\| *longest < args->maxlen) {
	/* We aren't going to use this perag */
	*longest = 0;
	xfs_perag_rele(pag);
	return error;
	}

	out_done:
	args->pag = pag;
	return 0;
	}

	static int
	xfs_filestream_create_association(
	struct xfs_bmalloca *ap,
	struct xfs_alloc_arg *args,
	xfs_ino_t pino,
	xfs_extlen_t *longest)
	{
	struct xfs_mount *mp = args->mp;
	struct xfs_mru_cache_elem *mru;
	struct xfs_fstrm_item *item;
	xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, pino);
	int flags = 0;
	int error;

	/* Changing parent AG association now, so remove the existing one. */
	mru = xfs_mru_cache_remove(mp->m_filestream, pino);
	if (mru) {
	struct xfs_fstrm_item *item =
	container_of(mru, struct xfs_fstrm_item, mru);

	agno = (pag_agno(item->pag) + 1) % mp->m_sb.sb_agcount;
	xfs_fstrm_free_func(mp, mru);
	} else if (xfs_is_inode32(mp)) {
	xfs_agnumber_t rotorstep = xfs_rotorstep;

	agno = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount;
	mp->m_agfrotor = (mp->m_agfrotor + 1) %
	(mp->m_sb.sb_agcount * rotorstep);
	}

	ap->blkno = XFS_AGB_TO_FSB(args->mp, agno, 0);
	xfs_bmap_adjacent(ap);

	if (ap->datatype & XFS_ALLOC_USERDATA)
	flags \|= XFS_PICK_USERDATA;
	if (ap->tp->t_flags & XFS_TRANS_LOWMODE)
	flags \|= XFS_PICK_LOWSPACE;

	*longest = ap->length;
	error = xfs_filestream_pick_ag(args, pino, agno, flags, longest);
	if (error)
	return error;

	/*
	* We are going to use this perag now, so create an assoication for it.
	* xfs_filestream_pick_ag() has already bumped the perag fstrms counter
	* for us, so all we need to do here is take another active reference to
	* the perag for the cached association.
	*
	* If we fail to store the association, we need to drop the fstrms
	* counter as well as drop the perag reference we take here for the
	* item. We do not need to return an error for this failure - as long as
	* we return a referenced AG, the allocation can still go ahead just
	* fine.
	*/
	item = kmalloc(sizeof(*item), GFP_KERNEL \| __GFP_RETRY_MAYFAIL);
	if (!item)
	goto out_put_fstrms;

	atomic_inc(&pag_group(args->pag)->xg_active_ref);
	item->pag = args->pag;
	error = xfs_mru_cache_insert(mp->m_filestream, pino, &item->mru);
	if (error)
	goto out_free_item;
	return 0;

	out_free_item:
	xfs_perag_rele(item->pag);
	kfree(item);
	out_put_fstrms:
	atomic_dec(&args->pag->pagf_fstrms);
	return 0;
	}

	/*
	* Search for an allocation group with a single extent large enough for
	* the request. First we look for an existing association and use that if it
	* is found. Otherwise, we create a new association by selecting an AG that fits
	* the allocation criteria.
	*
	* We return with a referenced perag in args->pag to indicate which AG we are
	* allocating into or an error with no references held.
	*/
	int
	xfs_filestream_select_ag(
	struct xfs_bmalloca *ap,
	struct xfs_alloc_arg *args,
	xfs_extlen_t *longest)
	{
	struct xfs_inode *pip;
	xfs_ino_t ino = 0;
	int error = 0;

	*longest = 0;
	args->total = ap->total;
	pip = xfs_filestream_get_parent(ap->ip);
	if (pip) {
	ino = pip->i_ino;
	error = xfs_filestream_lookup_association(ap, args, ino,
	longest);
	xfs_irele(pip);
	if (error)
	return error;
	if (*longest >= args->maxlen)
	goto out_select;
	if (ap->tp->t_flags & XFS_TRANS_LOWMODE)
	goto out_select;
	}

	error = xfs_filestream_create_association(ap, args, ino, longest);
	if (error)
	return error;

	out_select:
	ap->blkno = xfs_agbno_to_fsb(args->pag, 0);
	return 0;
	}

	void
	xfs_filestream_deassociate(
	struct xfs_inode *ip)
	{
	xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino);
	}

	int
	xfs_filestream_mount(
	xfs_mount_t *mp)
	{
	/*
	* The filestream timer tunable is currently fixed within the range of
	* one second to four minutes, with five seconds being the default. The
	* group count is somewhat arbitrary, but it'd be nice to adhere to the
	* timer tunable to within about 10 percent. This requires at least 10
	* groups.
	*/
	return xfs_mru_cache_create(&mp->m_filestream, mp,
	xfs_fstrm_centisecs * 10, 10, xfs_fstrm_free_func);
	}

	void
	xfs_filestream_unmount(
	xfs_mount_t *mp)
	{
	xfs_mru_cache_destroy(mp->m_filestream);
	}