upload tizen1.0 sourceHEADmaster2.0alpha

1 files changed, 818 insertions, 0 deletions

diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
new file mode 100644
index 00000000..9b715dce
--- /dev/null
+++ b/fs/xfs/xfs_filestream.c
@@ -0,0 +1,818 @@
+/*
+ * Copyright (c) 2006-2007 Silicon Graphics, 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.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include "xfs.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inum.h"
+#include "xfs_dinode.h"
+#include "xfs_inode.h"
+#include "xfs_ag.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_bmap.h"
+#include "xfs_alloc.h"
+#include "xfs_utils.h"
+#include "xfs_mru_cache.h"
+#include "xfs_filestream.h"
+#include "xfs_trace.h"
+
+#ifdef XFS_FILESTREAMS_TRACE
+
+ktrace_t *xfs_filestreams_trace_buf;
+
+STATIC void
+xfs_filestreams_trace(
+	xfs_mount_t	*mp,	/* mount point */
+	int		type,	/* type of trace */
+	const char	*func,	/* source function */
+	int		line,	/* source line number */
+	__psunsigned_t	arg0,
+	__psunsigned_t	arg1,
+	__psunsigned_t	arg2,
+	__psunsigned_t	arg3,
+	__psunsigned_t	arg4,
+	__psunsigned_t	arg5)
+{
+	ktrace_enter(xfs_filestreams_trace_buf,
+		(void *)(__psint_t)(type | (line << 16)),
+		(void *)func,
+		(void *)(__psunsigned_t)current_pid(),
+		(void *)mp,
+		(void *)(__psunsigned_t)arg0,
+		(void *)(__psunsigned_t)arg1,
+		(void *)(__psunsigned_t)arg2,
+		(void *)(__psunsigned_t)arg3,
+		(void *)(__psunsigned_t)arg4,
+		(void *)(__psunsigned_t)arg5,
+		NULL, NULL, NULL, NULL, NULL, NULL);
+}
+
+#define TRACE0(mp,t)			TRACE6(mp,t,0,0,0,0,0,0)
+#define TRACE1(mp,t,a0)			TRACE6(mp,t,a0,0,0,0,0,0)
+#define TRACE2(mp,t,a0,a1)		TRACE6(mp,t,a0,a1,0,0,0,0)
+#define TRACE3(mp,t,a0,a1,a2)		TRACE6(mp,t,a0,a1,a2,0,0,0)
+#define TRACE4(mp,t,a0,a1,a2,a3)	TRACE6(mp,t,a0,a1,a2,a3,0,0)
+#define TRACE5(mp,t,a0,a1,a2,a3,a4)	TRACE6(mp,t,a0,a1,a2,a3,a4,0)
+#define TRACE6(mp,t,a0,a1,a2,a3,a4,a5) \
+	xfs_filestreams_trace(mp, t, __func__, __LINE__, \
+				(__psunsigned_t)a0, (__psunsigned_t)a1, \
+				(__psunsigned_t)a2, (__psunsigned_t)a3, \
+				(__psunsigned_t)a4, (__psunsigned_t)a5)
+
+#define TRACE_AG_SCAN(mp, ag, ag2) \
+		TRACE2(mp, XFS_FSTRM_KTRACE_AGSCAN, ag, ag2);
+#define TRACE_AG_PICK1(mp, max_ag, maxfree) \
+		TRACE2(mp, XFS_FSTRM_KTRACE_AGPICK1, max_ag, maxfree);
+#define TRACE_AG_PICK2(mp, ag, ag2, cnt, free, scan, flag) \
+		TRACE6(mp, XFS_FSTRM_KTRACE_AGPICK2, ag, ag2, \
+			 cnt, free, scan, flag)
+#define TRACE_UPDATE(mp, ip, ag, cnt, ag2, cnt2) \
+		TRACE5(mp, XFS_FSTRM_KTRACE_UPDATE, ip, ag, cnt, ag2, cnt2)
+#define TRACE_FREE(mp, ip, pip, ag, cnt) \
+		TRACE4(mp, XFS_FSTRM_KTRACE_FREE, ip, pip, ag, cnt)
+#define TRACE_LOOKUP(mp, ip, pip, ag, cnt) \
+		TRACE4(mp, XFS_FSTRM_KTRACE_ITEM_LOOKUP, ip, pip, ag, cnt)
+#define TRACE_ASSOCIATE(mp, ip, pip, ag, cnt) \
+		TRACE4(mp, XFS_FSTRM_KTRACE_ASSOCIATE, ip, pip, ag, cnt)
+#define TRACE_MOVEAG(mp, ip, pip, oag, ocnt, nag, ncnt) \
+		TRACE6(mp, XFS_FSTRM_KTRACE_MOVEAG, ip, pip, oag, ocnt, nag, ncnt)
+#define TRACE_ORPHAN(mp, ip, ag) \
+		TRACE2(mp, XFS_FSTRM_KTRACE_ORPHAN, ip, ag);
+
+
+#else
+#define TRACE_AG_SCAN(mp, ag, ag2)
+#define TRACE_AG_PICK1(mp, max_ag, maxfree)
+#define TRACE_AG_PICK2(mp, ag, ag2, cnt, free, scan, flag)
+#define TRACE_UPDATE(mp, ip, ag, cnt, ag2, cnt2)
+#define TRACE_FREE(mp, ip, pip, ag, cnt)
+#define TRACE_LOOKUP(mp, ip, pip, ag, cnt)
+#define TRACE_ASSOCIATE(mp, ip, pip, ag, cnt)
+#define TRACE_MOVEAG(mp, ip, pip, oag, ocnt, nag, ncnt)
+#define TRACE_ORPHAN(mp, ip, ag)
+#endif
+
+static kmem_zone_t *item_zone;
+
+/*
+ * Structure for associating a file or a directory with an allocation group.
+ * The parent directory pointer is only needed for files, but since there will
+ * generally be vastly more files than directories in the cache, using the same
+ * data structure simplifies the code with very little memory overhead.
+ */
+typedef struct fstrm_item
+{
+	xfs_agnumber_t	ag;	/* AG currently in use for the file/directory. */
+	xfs_inode_t	*ip;	/* inode self-pointer. */
+	xfs_inode_t	*pip;	/* Parent directory inode pointer. */
+} fstrm_item_t;
+
+/*
+ * Allocation group filestream associations are tracked with per-ag atomic
+ * counters.  These counters allow _xfs_filestream_pick_ag() to tell whether a
+ * particular AG already has active filestreams associated with it. The mount
+ * point's m_peraglock is used to protect these counters from per-ag array
+ * re-allocation during a growfs operation.  When xfs_growfs_data_private() is
+ * about to reallocate the array, it calls xfs_filestream_flush() with the
+ * m_peraglock held in write mode.
+ *
+ * Since xfs_mru_cache_flush() guarantees that all the free functions for all
+ * the cache elements have finished executing before it returns, it's safe for
+ * the free functions to use the atomic counters without m_peraglock protection.
+ * This allows the implementation of xfs_fstrm_free_func() to be agnostic about
+ * whether it was called with the m_peraglock held in read mode, write mode or
+ * not held at all.  The race condition this addresses is the following:
+ *
+ *  - The work queue scheduler fires and pulls a filestream directory cache
+ *    element off the LRU end of the cache for deletion, then gets pre-empted.
+ *  - A growfs operation grabs the m_peraglock in write mode, flushes all the
+ *    remaining items from the cache and reallocates the mount point's per-ag
+ *    array, resetting all the counters to zero.
+ *  - The work queue thread resumes and calls the free function for the element
+ *    it started cleaning up earlier.  In the process it decrements the
+ *    filestreams counter for an AG that now has no references.
+ *
+ * With a shrinkfs feature, the above scenario could panic the system.
+ *
+ * All other uses of the following macros should be protected by either the
+ * m_peraglock held in read mode, or the cache's internal locking exposed by the
+ * interval between a call to xfs_mru_cache_lookup() and a call to
+ * xfs_mru_cache_done().  In addition, the m_peraglock must be held in read mode
+ * when new elements are added to the cache.
+ *
+ * Combined, these locking rules ensure that no associations will ever exist in
+ * the cache that reference per-ag array elements that have since been
+ * reallocated.
+ */
+static int
+xfs_filestream_peek_ag(
+	xfs_mount_t	*mp,
+	xfs_agnumber_t	agno)
+{
+	struct xfs_perag *pag;
+	int		ret;
+
+	pag = xfs_perag_get(mp, agno);
+	ret = atomic_read(&pag->pagf_fstrms);
+	xfs_perag_put(pag);
+	return ret;
+}
+
+static int
+xfs_filestream_get_ag(
+	xfs_mount_t	*mp,
+	xfs_agnumber_t	agno)
+{
+	struct xfs_perag *pag;
+	int		ret;
+
+	pag = xfs_perag_get(mp, agno);
+	ret = atomic_inc_return(&pag->pagf_fstrms);
+	xfs_perag_put(pag);
+	return ret;
+}
+
+static void
+xfs_filestream_put_ag(
+	xfs_mount_t	*mp,
+	xfs_agnumber_t	agno)
+{
+	struct xfs_perag *pag;
+
+	pag = xfs_perag_get(mp, agno);
+	atomic_dec(&pag->pagf_fstrms);
+	xfs_perag_put(pag);
+}
+
+/*
+ * Scan the AGs starting at startag looking for an AG that isn't in use and has
+ * at least minlen blocks free.
+ */
+static int
+_xfs_filestream_pick_ag(
+	xfs_mount_t	*mp,
+	xfs_agnumber_t	startag,
+	xfs_agnumber_t	*agp,
+	int		flags,
+	xfs_extlen_t	minlen)
+{
+	int		streams, max_streams;
+	int		err, trylock, nscan;
+	xfs_extlen_t	longest, free, minfree, maxfree = 0;
+	xfs_agnumber_t	ag, max_ag = NULLAGNUMBER;
+	struct xfs_perag *pag;
+
+	/* 2% of an AG's blocks must be free for it to be chosen. */
+	minfree = mp->m_sb.sb_agblocks / 50;
+
+	ag = startag;
+	*agp = NULLAGNUMBER;
+
+	/* For the first pass, don't sleep trying to init the per-AG. */
+	trylock = XFS_ALLOC_FLAG_TRYLOCK;
+
+	for (nscan = 0; 1; nscan++) {
+		pag = xfs_perag_get(mp, ag);
+		TRACE_AG_SCAN(mp, ag, atomic_read(&pag->pagf_fstrms));
+
+		if (!pag->pagf_init) {
+			err = xfs_alloc_pagf_init(mp, NULL, ag, trylock);
+			if (err && !trylock) {
+				xfs_perag_put(pag);
+				return err;
+			}
+		}
+
+		/* Might fail sometimes during the 1st pass with trylock set. */
+		if (!pag->pagf_init)
+			goto next_ag;
+
+		/* Keep track of the AG with the most free blocks. */
+		if (pag->pagf_freeblks > maxfree) {
+			maxfree = pag->pagf_freeblks;
+			max_streams = atomic_read(&pag->pagf_fstrms);
+			max_ag = ag;
+		}
+
+		/*
+		 * 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 (xfs_filestream_get_ag(mp, ag) > 1) {
+			xfs_filestream_put_ag(mp, ag);
+			goto next_ag;
+		}
+
+		longest = xfs_alloc_longest_free_extent(mp, pag);
+		if (((minlen && longest >= minlen) ||
+		     (!minlen && pag->pagf_freeblks >= minfree)) &&
+		    (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) ||
+		     (flags & XFS_PICK_LOWSPACE))) {
+
+			/* Break out, retaining the reference on the AG. */
+			free = pag->pagf_freeblks;
+			streams = atomic_read(&pag->pagf_fstrms);
+			xfs_perag_put(pag);
+			*agp = ag;
+			break;
+		}
+
+		/* Drop the reference on this AG, it's not usable. */
+		xfs_filestream_put_ag(mp, ag);
+next_ag:
+		xfs_perag_put(pag);
+		/* Move to the next AG, wrapping to AG 0 if necessary. */
+		if (++ag >= mp->m_sb.sb_agcount)
+			ag = 0;
+
+		/* If a full pass of the AGs hasn't been done yet, continue. */
+		if (ag != startag)
+			continue;
+
+		/* Allow sleeping in xfs_alloc_pagf_init() on the 2nd pass. */
+		if (trylock != 0) {
+			trylock = 0;
+			continue;
+		}
+
+		/* Finally, if lowspace wasn't set, set it for the 3rd pass. */
+		if (!(flags & XFS_PICK_LOWSPACE)) {
+			flags |= XFS_PICK_LOWSPACE;
+			continue;
+		}
+
+		/*
+		 * Take the AG with the most free space, regardless of whether
+		 * it's already in use by another filestream.
+		 */
+		if (max_ag != NULLAGNUMBER) {
+			xfs_filestream_get_ag(mp, max_ag);
+			TRACE_AG_PICK1(mp, max_ag, maxfree);
+			streams = max_streams;
+			free = maxfree;
+			*agp = max_ag;
+			break;
+		}
+
+		/* take AG 0 if none matched */
+		TRACE_AG_PICK1(mp, max_ag, maxfree);
+		*agp = 0;
+		return 0;
+	}
+
+	TRACE_AG_PICK2(mp, startag, *agp, streams, free, nscan, flags);
+
+	return 0;
+}
+
+/*
+ * Set the allocation group number for a file or a directory, updating inode
+ * references and per-AG references as appropriate.
+ */
+static int
+_xfs_filestream_update_ag(
+	xfs_inode_t	*ip,
+	xfs_inode_t	*pip,
+	xfs_agnumber_t	ag)
+{
+	int		err = 0;
+	xfs_mount_t	*mp;
+	xfs_mru_cache_t	*cache;
+	fstrm_item_t	*item;
+	xfs_agnumber_t	old_ag;
+	xfs_inode_t	*old_pip;
+
+	/*
+	 * Either ip is a regular file and pip is a directory, or ip is a
+	 * directory and pip is NULL.
+	 */
+	ASSERT(ip && (((ip->i_d.di_mode & S_IFREG) && pip &&
+	               (pip->i_d.di_mode & S_IFDIR)) ||
+	              ((ip->i_d.di_mode & S_IFDIR) && !pip)));
+
+	mp = ip->i_mount;
+	cache = mp->m_filestream;
+
+	item = xfs_mru_cache_lookup(cache, ip->i_ino);
+	if (item) {
+		ASSERT(item->ip == ip);
+		old_ag = item->ag;
+		item->ag = ag;
+		old_pip = item->pip;
+		item->pip = pip;
+		xfs_mru_cache_done(cache);
+
+		/*
+		 * If the AG has changed, drop the old ref and take a new one,
+		 * effectively transferring the reference from old to new AG.
+		 */
+		if (ag != old_ag) {
+			xfs_filestream_put_ag(mp, old_ag);
+			xfs_filestream_get_ag(mp, ag);
+		}
+
+		/*
+		 * If ip is a file and its pip has changed, drop the old ref and
+		 * take a new one.
+		 */
+		if (pip && pip != old_pip) {
+			IRELE(old_pip);
+			IHOLD(pip);
+		}
+
+		TRACE_UPDATE(mp, ip, old_ag, xfs_filestream_peek_ag(mp, old_ag),
+				ag, xfs_filestream_peek_ag(mp, ag));
+		return 0;
+	}
+
+	item = kmem_zone_zalloc(item_zone, KM_MAYFAIL);
+	if (!item)
+		return ENOMEM;
+
+	item->ag = ag;
+	item->ip = ip;
+	item->pip = pip;
+
+	err = xfs_mru_cache_insert(cache, ip->i_ino, item);
+	if (err) {
+		kmem_zone_free(item_zone, item);
+		return err;
+	}
+
+	/* Take a reference on the AG. */
+	xfs_filestream_get_ag(mp, ag);
+
+	/*
+	 * Take a reference on the inode itself regardless of whether it's a
+	 * regular file or a directory.
+	 */
+	IHOLD(ip);
+
+	/*
+	 * In the case of a regular file, take a reference on the parent inode
+	 * as well to ensure it remains in-core.
+	 */
+	if (pip)
+		IHOLD(pip);
+
+	TRACE_UPDATE(mp, ip, ag, xfs_filestream_peek_ag(mp, ag),
+			ag, xfs_filestream_peek_ag(mp, ag));
+
+	return 0;
+}
+
+/* xfs_fstrm_free_func(): callback for freeing cached stream items. */
+STATIC void
+xfs_fstrm_free_func(
+	unsigned long	ino,
+	void		*data)
+{
+	fstrm_item_t	*item  = (fstrm_item_t *)data;
+	xfs_inode_t	*ip = item->ip;
+
+	ASSERT(ip->i_ino == ino);
+
+	xfs_iflags_clear(ip, XFS_IFILESTREAM);
+
+	/* Drop the reference taken on the AG when the item was added. */
+	xfs_filestream_put_ag(ip->i_mount, item->ag);
+
+	TRACE_FREE(ip->i_mount, ip, item->pip, item->ag,
+		xfs_filestream_peek_ag(ip->i_mount, item->ag));
+
+	/*
+	 * _xfs_filestream_update_ag() always takes a reference on the inode
+	 * itself, whether it's a file or a directory.  Release it here.
+	 * This can result in the inode being freed and so we must
+	 * not hold any inode locks when freeing filesstreams objects
+	 * otherwise we can deadlock here.
+	 */
+	IRELE(ip);
+
+	/*
+	 * In the case of a regular file, _xfs_filestream_update_ag() also
+	 * takes a ref on the parent inode to keep it in-core.  Release that
+	 * too.
+	 */
+	if (item->pip)
+		IRELE(item->pip);
+
+	/* Finally, free the memory allocated for the item. */
+	kmem_zone_free(item_zone, item);
+}
+
+/*
+ * xfs_filestream_init() is called at xfs initialisation time to set up the
+ * memory zone that will be used for filestream data structure allocation.
+ */
+int
+xfs_filestream_init(void)
+{
+	item_zone = kmem_zone_init(sizeof(fstrm_item_t), "fstrm_item");
+	if (!item_zone)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/*
+ * xfs_filestream_uninit() is called at xfs termination time to destroy the
+ * memory zone that was used for filestream data structure allocation.
+ */
+void
+xfs_filestream_uninit(void)
+{
+	kmem_zone_destroy(item_zone);
+}
+
+/*
+ * xfs_filestream_mount() is called when a file system is mounted with the
+ * filestream option.  It is responsible for allocating the data structures
+ * needed to track the new file system's file streams.
+ */
+int
+xfs_filestream_mount(
+	xfs_mount_t	*mp)
+{
+	int		err;
+	unsigned int	lifetime, grp_count;
+
+	/*
+	 * 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.
+	 */
+	lifetime  = xfs_fstrm_centisecs * 10;
+	grp_count = 10;
+
+	err = xfs_mru_cache_create(&mp->m_filestream, lifetime, grp_count,
+	                     xfs_fstrm_free_func);
+
+	return err;
+}
+
+/*
+ * xfs_filestream_unmount() is called when a file system that was mounted with
+ * the filestream option is unmounted.  It drains the data structures created
+ * to track the file system's file streams and frees all the memory that was
+ * allocated.
+ */
+void
+xfs_filestream_unmount(
+	xfs_mount_t	*mp)
+{
+	xfs_mru_cache_destroy(mp->m_filestream);
+}
+
+/*
+ * Return the AG of the filestream the file or directory belongs to, or
+ * NULLAGNUMBER otherwise.
+ */
+xfs_agnumber_t
+xfs_filestream_lookup_ag(
+	xfs_inode_t	*ip)
+{
+	xfs_mru_cache_t	*cache;
+	fstrm_item_t	*item;
+	xfs_agnumber_t	ag;
+	int		ref;
+
+	if (!(ip->i_d.di_mode & (S_IFREG | S_IFDIR))) {
+		ASSERT(0);
+		return NULLAGNUMBER;
+	}
+
+	cache = ip->i_mount->m_filestream;
+	item = xfs_mru_cache_lookup(cache, ip->i_ino);
+	if (!item) {
+		TRACE_LOOKUP(ip->i_mount, ip, NULL, NULLAGNUMBER, 0);
+		return NULLAGNUMBER;
+	}
+
+	ASSERT(ip == item->ip);
+	ag = item->ag;
+	ref = xfs_filestream_peek_ag(ip->i_mount, ag);
+	xfs_mru_cache_done(cache);
+
+	TRACE_LOOKUP(ip->i_mount, ip, item->pip, ag, ref);
+	return ag;
+}
+
+/*
+ * xfs_filestream_associate() should only be called to associate a regular file
+ * with its parent directory.  Calling it with a child directory isn't
+ * appropriate because filestreams don't apply to entire directory hierarchies.
+ * Creating a file in a child directory of an existing filestream directory
+ * starts a new filestream with its own allocation group association.
+ *
+ * Returns < 0 on error, 0 if successful association occurred, > 0 if
+ * we failed to get an association because of locking issues.
+ */
+int
+xfs_filestream_associate(
+	xfs_inode_t	*pip,
+	xfs_inode_t	*ip)
+{
+	xfs_mount_t	*mp;
+	xfs_mru_cache_t	*cache;
+	fstrm_item_t	*item;
+	xfs_agnumber_t	ag, rotorstep, startag;
+	int		err = 0;
+
+	ASSERT(pip->i_d.di_mode & S_IFDIR);
+	ASSERT(ip->i_d.di_mode & S_IFREG);
+	if (!(pip->i_d.di_mode & S_IFDIR) || !(ip->i_d.di_mode & S_IFREG))
+		return -EINVAL;
+
+	mp = pip->i_mount;
+	cache = mp->m_filestream;
+
+	/*
+	 * We have a problem, Houston.
+	 *
+	 * Taking the iolock here violates inode locking order - we already
+	 * hold the ilock. Hence if we block getting this lock we may never
+	 * wake. Unfortunately, that means if we can't get the lock, we're
+	 * screwed in terms of getting a stream association - we can't spin
+	 * waiting for the lock because someone else is waiting on the lock we
+	 * hold and we cannot drop that as we are in a transaction here.
+	 *
+	 * Lucky for us, this inversion is not a problem because it's a
+	 * directory inode that we are trying to lock here.
+	 *
+	 * So, if we can't get the iolock without sleeping then just give up
+	 */
+	if (!xfs_ilock_nowait(pip, XFS_IOLOCK_EXCL))
+		return 1;
+
+	/* If the parent directory is already in the cache, use its AG. */
+	item = xfs_mru_cache_lookup(cache, pip->i_ino);
+	if (item) {
+		ASSERT(item->ip == pip);
+		ag = item->ag;
+		xfs_mru_cache_done(cache);
+
+		TRACE_LOOKUP(mp, pip, pip, ag, xfs_filestream_peek_ag(mp, ag));
+		err = _xfs_filestream_update_ag(ip, pip, ag);
+
+		goto exit;
+	}
+
+	/*
+	 * Set the starting AG using the rotor for inode32, otherwise
+	 * use the directory inode's AG.
+	 */
+	if (mp->m_flags & XFS_MOUNT_32BITINODES) {
+		rotorstep = xfs_rotorstep;
+		startag = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount;
+		mp->m_agfrotor = (mp->m_agfrotor + 1) %
+		                 (mp->m_sb.sb_agcount * rotorstep);
+	} else
+		startag = XFS_INO_TO_AGNO(mp, pip->i_ino);
+
+	/* Pick a new AG for the parent inode starting at startag. */
+	err = _xfs_filestream_pick_ag(mp, startag, &ag, 0, 0);
+	if (err || ag == NULLAGNUMBER)
+		goto exit_did_pick;
+
+	/* Associate the parent inode with the AG. */
+	err = _xfs_filestream_update_ag(pip, NULL, ag);
+	if (err)
+		goto exit_did_pick;
+
+	/* Associate the file inode with the AG. */
+	err = _xfs_filestream_update_ag(ip, pip, ag);
+	if (err)
+		goto exit_did_pick;
+
+	TRACE_ASSOCIATE(mp, ip, pip, ag, xfs_filestream_peek_ag(mp, ag));
+
+exit_did_pick:
+	/*
+	 * If _xfs_filestream_pick_ag() returned a valid AG, remove the
+	 * reference it took on it, since the file and directory will have taken
+	 * their own now if they were successfully cached.
+	 */
+	if (ag != NULLAGNUMBER)
+		xfs_filestream_put_ag(mp, ag);
+
+exit:
+	xfs_iunlock(pip, XFS_IOLOCK_EXCL);
+	return -err;
+}
+
+/*
+ * Pick a new allocation group for the current file and its file stream.  This
+ * function is called by xfs_bmap_filestreams() with the mount point's per-ag
+ * lock held.
+ */
+int
+xfs_filestream_new_ag(
+	xfs_bmalloca_t	*ap,
+	xfs_agnumber_t	*agp)
+{
+	int		flags, err;
+	xfs_inode_t	*ip, *pip = NULL;
+	xfs_mount_t	*mp;
+	xfs_mru_cache_t	*cache;
+	xfs_extlen_t	minlen;
+	fstrm_item_t	*dir, *file;
+	xfs_agnumber_t	ag = NULLAGNUMBER;
+
+	ip = ap->ip;
+	mp = ip->i_mount;
+	cache = mp->m_filestream;
+	minlen = ap->alen;
+	*agp = NULLAGNUMBER;
+
+	/*
+	 * Look for the file in the cache, removing it if it's found.  Doing
+	 * this allows it to be held across the dir lookup that follows.
+	 */
+	file = xfs_mru_cache_remove(cache, ip->i_ino);
+	if (file) {
+		ASSERT(ip == file->ip);
+
+		/* Save the file's parent inode and old AG number for later. */
+		pip = file->pip;
+		ag = file->ag;
+
+		/* Look for the file's directory in the cache. */
+		dir = xfs_mru_cache_lookup(cache, pip->i_ino);
+		if (dir) {
+			ASSERT(pip == dir->ip);
+
+			/*
+			 * If the directory has already moved on to a new AG,
+			 * use that AG as the new AG for the file. Don't
+			 * forget to twiddle the AG refcounts to match the
+			 * movement.
+			 */
+			if (dir->ag != file->ag) {
+				xfs_filestream_put_ag(mp, file->ag);
+				xfs_filestream_get_ag(mp, dir->ag);
+				*agp = file->ag = dir->ag;
+			}
+
+			xfs_mru_cache_done(cache);
+		}
+
+		/*
+		 * Put the file back in the cache.  If this fails, the free
+		 * function needs to be called to tidy up in the same way as if
+		 * the item had simply expired from the cache.
+		 */
+		err = xfs_mru_cache_insert(cache, ip->i_ino, file);
+		if (err) {
+			xfs_fstrm_free_func(ip->i_ino, file);
+			return err;
+		}
+
+		/*
+		 * If the file's AG was moved to the directory's new AG, there's
+		 * nothing more to be done.
+		 */
+		if (*agp != NULLAGNUMBER) {
+			TRACE_MOVEAG(mp, ip, pip,
+					ag, xfs_filestream_peek_ag(mp, ag),
+					*agp, xfs_filestream_peek_ag(mp, *agp));
+			return 0;
+		}
+	}
+
+	/*
+	 * If the file's parent directory is known, take its iolock in exclusive
+	 * mode to prevent two sibling files from racing each other to migrate
+	 * themselves and their parent to different AGs.
+	 */
+	if (pip)
+		xfs_ilock(pip, XFS_IOLOCK_EXCL);
+
+	/*
+	 * A new AG needs to be found for the file.  If the file's parent
+	 * directory is also known, it will be moved to the new AG as well to
+	 * ensure that files created inside it in future use the new AG.
+	 */
+	ag = (ag == NULLAGNUMBER) ? 0 : (ag + 1) % mp->m_sb.sb_agcount;
+	flags = (ap->userdata ? XFS_PICK_USERDATA : 0) |
+	        (ap->low ? XFS_PICK_LOWSPACE : 0);
+
+	err = _xfs_filestream_pick_ag(mp, ag, agp, flags, minlen);
+	if (err || *agp == NULLAGNUMBER)
+		goto exit;
+
+	/*
+	 * If the file wasn't found in the file cache, then its parent directory
+	 * inode isn't known.  For this to have happened, the file must either
+	 * be pre-existing, or it was created long enough ago that its cache
+	 * entry has expired.  This isn't the sort of usage that the filestreams
+	 * allocator is trying to optimise, so there's no point trying to track
+	 * its new AG somehow in the filestream data structures.
+	 */
+	if (!pip) {
+		TRACE_ORPHAN(mp, ip, *agp);
+		goto exit;
+	}
+
+	/* Associate the parent inode with the AG. */
+	err = _xfs_filestream_update_ag(pip, NULL, *agp);
+	if (err)
+		goto exit;
+
+	/* Associate the file inode with the AG. */
+	err = _xfs_filestream_update_ag(ip, pip, *agp);
+	if (err)
+		goto exit;
+
+	TRACE_MOVEAG(mp, ip, pip, NULLAGNUMBER, 0,
+			*agp, xfs_filestream_peek_ag(mp, *agp));
+
+exit:
+	/*
+	 * If _xfs_filestream_pick_ag() returned a valid AG, remove the
+	 * reference it took on it, since the file and directory will have taken
+	 * their own now if they were successfully cached.
+	 */
+	if (*agp != NULLAGNUMBER)
+		xfs_filestream_put_ag(mp, *agp);
+	else
+		*agp = 0;
+
+	if (pip)
+		xfs_iunlock(pip, XFS_IOLOCK_EXCL);
+
+	return err;
+}
+
+/*
+ * Remove an association between an inode and a filestream object.
+ * Typically this is done on last close of an unlinked file.
+ */
+void
+xfs_filestream_deassociate(
+	xfs_inode_t	*ip)
+{
+	xfs_mru_cache_t	*cache = ip->i_mount->m_filestream;
+
+	xfs_mru_cache_delete(cache, ip->i_ino);
+}