xfs: rewrite the filestream allocator using the dentry cache

In Linux we will always be able to find a parent inode for file that are
undergoing I/O.  Use this to simply the file stream allocator by only
keeping track of parent inodes.

Signed-off-by: Christoph Hellwig <hch@lst.de>

3 files changed, 171 insertions, 544 deletions

diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index c422110c7c43..ff6f90215c8a 100644
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2006-2007 Silicon Graphics, Inc.
+ * Copyright (c) 2014 Christoph Hellwig.
  * All Rights Reserved.
  *
  * This program is free software; you can redistribute it and/or
@@ -32,101 +33,28 @@
 #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
-{
-        struct xfs_mru_cache_elem mru;
-        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;
+struct xfs_fstrm_item {
+        struct xfs_mru_cache_elem       mru;
+        struct xfs_inode                *ip;
+        xfs_agnumber_t                  ag; /* AG in use for this directory */
+};
+
+enum xfs_fstrm_alloc {
+        XFS_PICK_USERDATA = 1,
+        XFS_PICK_LOWSPACE = 2,
+};
 
 /*
  * Allocation group filestream associations are tracked with per-ag atomic
- * counters.  These counters allow _xfs_filestream_pick_ag() to tell whether a
+ * 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
@@ -201,23 +129,42 @@ xfs_filestream_put_ag(
         xfs_perag_put(pag);
 }
 
+static void
+xfs_fstrm_free_func(
+        struct xfs_mru_cache_elem *mru)
+{
+        struct xfs_fstrm_item   *item =
+                container_of(mru, struct xfs_fstrm_item, mru);
+
+        xfs_filestream_put_ag(item->ip->i_mount, item->ag);
+
+        TRACE_FREE(mp, ip, NULL, item->ag,
+                   xfs_filestream_peek_ag(mp, item->ag));
+
+        kmem_zone_free(item_zone, item);
+}
+
 /*
  * 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)
+xfs_filestream_pick_ag(
+        struct xfs_inode        *ip,
+        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;
+        struct xfs_mount        *mp = ip->i_mount;
+        struct xfs_fstrm_item   *item;
+        struct xfs_perag        *pag;
+        xfs_extlen_t            longest, free, minfree, maxfree = 0;
+        xfs_agnumber_t          ag, max_ag = NULLAGNUMBER;
+        int                     streams, max_streams;
+        int                     err, trylock, nscan;
+
+        ASSERT(S_ISDIR(ip->i_d.di_mode));
 
         /* 2% of an AG's blocks must be free for it to be chosen. */
         minfree = mp->m_sb.sb_agblocks / 50;
@@ -321,205 +268,55 @@ next_ag:
 
         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;
-        fstrm_item_t    *item;
-        xfs_agnumber_t  old_ag;
-        xfs_inode_t     *old_pip;
-        struct xfs_mru_cache_elem *mru;
-
-        /*
-         * Either ip is a regular file and pip is a directory, or ip is a
-         * directory and pip is NULL.
-         */
-        ASSERT(ip && ((S_ISREG(ip->i_d.di_mode) && pip &&
-                       S_ISDIR(pip->i_d.di_mode)) ||
-                      (S_ISDIR(ip->i_d.di_mode) && !pip)));
-
-        mp = ip->i_mount;
-
-        mru = xfs_mru_cache_lookup(mp->m_filestream, ip->i_ino);
-        if (mru) {
-                item = container_of(mru, fstrm_item_t, mru);
-
-                ASSERT(item->ip == ip);
-                old_ag = item->ag;
-                item->ag = ag;
-                old_pip = item->pip;
-                item->pip = pip;
-                xfs_mru_cache_done(mp->m_filestream);
-
-                /*
-                 * 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));
+        if (*agp == NULLAGNUMBER)
                 return 0;
-        }
 
+        err = ENOMEM;
         item = kmem_zone_zalloc(item_zone, KM_MAYFAIL);
         if (!item)
-                return ENOMEM;
+                goto out_put_ag;
 
-        item->ag = ag;
+        item->ag = *agp;
         item->ip = ip;
-        item->pip = pip;
 
         err = xfs_mru_cache_insert(mp->m_filestream, ip->i_ino, &item->mru);
         if (err) {
-                kmem_zone_free(item_zone, item);
-                return err;
+                if (err == EEXIST)
+                        err = 0;
+                goto out_free_item;
         }
 
-        /* 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(
-        struct xfs_mru_cache_elem *mru)
-{
-        fstrm_item_t    *item =
-                container_of(mru, fstrm_item_t, mru);
-        xfs_inode_t     *ip = item->ip;
-
-        /* 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. */
+out_free_item:
         kmem_zone_free(item_zone, item);
+out_put_ag:
+        xfs_filestream_put_ag(mp, *agp);
+        return err;
 }
 
-/*
- * 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)
+static struct xfs_inode *
+xfs_filestream_get_parent(
+        struct xfs_inode        *ip)
 {
-        kmem_zone_destroy(item_zone);
-}
+        struct inode            *inode = VFS_I(ip), *dir = NULL;
+        struct dentry           *dentry, *parent;
 
-/*
- * 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;
+        dentry = d_find_alias(inode);
+        if (!dentry)
+                goto out;
 
-        /*
-         * 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;
+        parent = dget_parent(dentry);
+        if (!parent)
+                goto out_dput;
 
-        err = xfs_mru_cache_create(&mp->m_filestream, lifetime, grp_count,
-                             xfs_fstrm_free_func);
+        dir = igrab(parent->d_inode);
+        dput(parent);
 
-        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);
+out_dput:
+        dput(dentry);
+out:
+        return dir ? XFS_I(dir) : NULL;
 }
 
 /*
@@ -528,94 +325,61 @@ xfs_filestream_unmount(
  */
 xfs_agnumber_t
 xfs_filestream_lookup_ag(
-        xfs_inode_t     *ip)
+        struct xfs_inode        *ip)
 {
-        struct xfs_mount *mp = ip->i_mount;
+        struct xfs_mount        *mp = ip->i_mount;
+        struct xfs_fstrm_item   *item;
+        struct xfs_inode        *pip = NULL;
+        xfs_agnumber_t          ag = NULLAGNUMBER;
+        int                     ref = 0;
         struct xfs_mru_cache_elem *mru;
-        fstrm_item_t    *item;
-        xfs_agnumber_t  ag;
-        int             ref;
 
-        if (!S_ISREG(ip->i_d.di_mode) && !S_ISDIR(ip->i_d.di_mode)) {
-                ASSERT(0);
-                return NULLAGNUMBER;
-        }
+        ASSERT(S_ISREG(ip->i_d.di_mode));
 
-        mru = xfs_mru_cache_lookup(mp->m_filestream, ip->i_ino);
-        if (!mru) {
-                TRACE_LOOKUP(ip->i_mount, ip, NULL, NULLAGNUMBER, 0);
-                return NULLAGNUMBER;
-        }
+        pip = xfs_filestream_get_parent(ip);
+        if (!pip)
+                goto out;
+
+        mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino);
+        if (!mru)
+                goto out;
+
+        item = container_of(mru, struct xfs_fstrm_item, mru);
 
-        item = container_of(mru, fstrm_item_t, mru);
-        ASSERT(ip == item->ip);
         ag = item->ag;
-        ref = xfs_filestream_peek_ag(ip->i_mount, ag);
         xfs_mru_cache_done(mp->m_filestream);
 
-        TRACE_LOOKUP(ip->i_mount, ip, item->pip, ag, ref);
+        ref = xfs_filestream_peek_ag(ip->i_mount, ag);
+out:
+        TRACE_LOOKUP(mp, ip, pip, ag, ref);
+        IRELE(pip);
         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.
+ * Make sure a directory has a filestream associated with it.
  *
- * Returns < 0 on error, 0 if successful association occurred, > 0 if
- * we failed to get an association because of locking issues.
+ * This is called when creating regular files in an directory that has
+ * filestreams enabled, so that a stream is ready by the time we need it
+ * in the allocator for the files inside the directory.
  */
 int
 xfs_filestream_associate(
-        xfs_inode_t     *pip,
-        xfs_inode_t     *ip)
+        struct xfs_inode        *pip)
 {
+        struct xfs_mount        *mp = pip->i_mount;
         struct xfs_mru_cache_elem *mru;
-        xfs_mount_t     *mp;
-        fstrm_item_t    *item;
-        xfs_agnumber_t  ag, rotorstep, startag;
-        int             err = 0;
+        xfs_agnumber_t          startag, ag;
 
         ASSERT(S_ISDIR(pip->i_d.di_mode));
-        ASSERT(S_ISREG(ip->i_d.di_mode));
-        if (!S_ISDIR(pip->i_d.di_mode) || !S_ISREG(ip->i_d.di_mode))
-                return -EINVAL;
-
-        mp = pip->i_mount;
 
         /*
-         * 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 the directory already has a file stream associated we're done.
          */
-        if (!xfs_ilock_nowait(pip, XFS_IOLOCK_EXCL))
-                return 1;
-
-        /* If the parent directory is already in the cache, use its AG. */
         mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino);
         if (mru) {
-                item = container_of(mru, fstrm_item_t, mru);
-
-                ASSERT(item->ip == pip);
-                ag = item->ag;
                 xfs_mru_cache_done(mp->m_filestream);
-
-                TRACE_LOOKUP(mp, pip, pip, ag, xfs_filestream_peek_ag(mp, ag));
-                err = _xfs_filestream_update_ag(ip, pip, ag);
-
-                goto exit;
+                return 0;
         }
 
         /*
@@ -623,201 +387,107 @@ xfs_filestream_associate(
          * use the directory inode's AG.
          */
         if (mp->m_flags & XFS_MOUNT_32BITINODES) {
-                rotorstep = xfs_rotorstep;
+                xfs_agnumber_t   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;
+        return xfs_filestream_pick_ag(pip, startag, &ag, 0, 0);
 }
 
 /*
- * 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.
+ * Pick a new allocation group for the current file and its file stream.
+ *
+ * This is called when the allocator can't find a suitable extent in the
+ * current AG, and we have to move the stream into a new AG with more space.
  */
 int
 xfs_filestream_new_ag(
         struct xfs_bmalloca     *ap,
         xfs_agnumber_t          *agp)
 {
-        struct xfs_mru_cache_elem *mru, *mru2;
-        int             flags, err;
-        xfs_inode_t     *ip, *pip = NULL;
-        xfs_mount_t     *mp;
-        xfs_extlen_t    minlen;
-        fstrm_item_t    *dir, *file;
-        xfs_agnumber_t  ag = NULLAGNUMBER;
-
-        ip = ap->ip;
-        mp = ip->i_mount;
-        minlen = ap->length;
-        *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.
-         */
-        mru = xfs_mru_cache_remove(mp->m_filestream, ip->i_ino);
-        if (mru) {
-                file = container_of(mru, fstrm_item_t, mru);
-                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. */
-                mru2 = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino);
-                if (mru2) {
-                        dir = container_of(mru2, fstrm_item_t, mru);
-                        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;
-                        }
+        struct xfs_inode        *ip = ap->ip, *pip;
+        struct xfs_mount        *mp = ip->i_mount;
+        xfs_extlen_t            minlen = ap->length;
+        xfs_agnumber_t          startag = 0;
+        int                     flags, err = 0;
+        struct xfs_mru_cache_elem *mru;
 
-                        xfs_mru_cache_done(mp->m_filestream);
-                }
+        *agp = NULLAGNUMBER;
 
-                /*
-                 * 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(mp->m_filestream, ip->i_ino, mru);
-                if (err) {
-                        xfs_fstrm_free_func(mru);
-                        return err;
-                }
+        pip = xfs_filestream_get_parent(ip);
+        if (!pip)
+                goto exit;
 
-                /*
-                 * 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;
-                }
+        mru = xfs_mru_cache_remove(mp->m_filestream, pip->i_ino);
+        if (mru) {
+                struct xfs_fstrm_item *item =
+                        container_of(mru, struct xfs_fstrm_item, mru);
+                startag = (item->ag + 1) % mp->m_sb.sb_agcount;
         }
 
-        /*
-         * 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.
-         *
-         * Note that we lock the parent directory iolock inside the child
-         * iolock here.  That's fine as we never hold both parent and child
-         * iolock in any other place.  This is different from the ilock,
-         * which requires locking of the child after the parent for namespace
-         * operations.
-         */
-        if (pip)
-                xfs_ilock(pip, XFS_IOLOCK_EXCL | XFS_IOLOCK_PARENT);
-
-        /*
-         * 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->flist->xbf_low ? XFS_PICK_LOWSPACE : 0);
 
-        err = _xfs_filestream_pick_ag(mp, ag, agp, flags, minlen);
-        if (err || *agp == NULLAGNUMBER)
-                goto exit;
+        err = xfs_filestream_pick_ag(pip, startag, agp, flags, minlen);
 
         /*
-         * 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.
+         * Only free the item here so we skip over the old AG earlier.
          */
-        if (!pip) {
-                TRACE_ORPHAN(mp, ip, *agp);
-                goto exit;
-        }
+        if (mru)
+                xfs_fstrm_free_func(mru);
 
-        /* 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;
+        IRELE(pip);
+exit:
+        if (*agp == NULLAGNUMBER)
+                *agp = 0;
+        return err;
+}
 
-        TRACE_MOVEAG(mp, ip, pip, NULLAGNUMBER, 0,
-                        *agp, xfs_filestream_peek_ag(mp, *agp));
+void
+xfs_filestream_deassociate(
+        struct xfs_inode        *ip)
+{
+        xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino);
+}
 
-exit:
+int
+xfs_filestream_mount(
+        xfs_mount_t     *mp)
+{
         /*
-         * 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.
+         * 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.
          */
-        if (*agp != NULLAGNUMBER)
-                xfs_filestream_put_ag(mp, *agp);
-        else
-                *agp = 0;
+        return xfs_mru_cache_create(&mp->m_filestream, xfs_fstrm_centisecs * 10,
+                                    10, xfs_fstrm_free_func);
+}
 
-        if (pip)
-                xfs_iunlock(pip, XFS_IOLOCK_EXCL);
+void
+xfs_filestream_unmount(
+        xfs_mount_t     *mp)
+{
+        xfs_mru_cache_destroy(mp->m_filestream);
+}
 
-        return err;
+
+/* needs to return a positive errno for the init path */
+int
+xfs_filestream_init(void)
+{
+        item_zone = kmem_zone_init(sizeof(struct xfs_fstrm_item), "fstrm_item");
+        if (!item_zone)
+                return -ENOMEM;
+        return 0;
 }
 
-/*
- * 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_filestream_uninit(void)
 {
-        xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino);
+        kmem_zone_destroy(item_zone);
 }
diff --git a/fs/xfs/xfs_filestream.h b/fs/xfs/xfs_filestream.h
index c4fa9a0cd62f..e3a25f891d08 100644
--- a/fs/xfs/xfs_filestream.h
+++ b/fs/xfs/xfs_filestream.h
@@ -20,44 +20,17 @@
 
 struct xfs_mount;
 struct xfs_inode;
-struct xfs_perag;
 struct xfs_bmalloca;
 
-#ifdef XFS_FILESTREAMS_TRACE
-#define XFS_FSTRM_KTRACE_INFO           1
-#define XFS_FSTRM_KTRACE_AGSCAN         2
-#define XFS_FSTRM_KTRACE_AGPICK1        3
-#define XFS_FSTRM_KTRACE_AGPICK2        4
-#define XFS_FSTRM_KTRACE_UPDATE         5
-#define XFS_FSTRM_KTRACE_FREE           6
-#define XFS_FSTRM_KTRACE_ITEM_LOOKUP    7
-#define XFS_FSTRM_KTRACE_ASSOCIATE      8
-#define XFS_FSTRM_KTRACE_MOVEAG         9
-#define XFS_FSTRM_KTRACE_ORPHAN         10
-
-#define XFS_FSTRM_KTRACE_SIZE   16384
-extern ktrace_t *xfs_filestreams_trace_buf;
-
-#endif
-
-/* allocation selection flags */
-typedef enum xfs_fstrm_alloc {
-        XFS_PICK_USERDATA = 1,
-        XFS_PICK_LOWSPACE = 2,
-} xfs_fstrm_alloc_t;
-
-/* prototypes for filestream.c */
 int xfs_filestream_init(void);
 void xfs_filestream_uninit(void);
 int xfs_filestream_mount(struct xfs_mount *mp);
 void xfs_filestream_unmount(struct xfs_mount *mp);
-xfs_agnumber_t xfs_filestream_lookup_ag(struct xfs_inode *ip);
-int xfs_filestream_associate(struct xfs_inode *dip, struct xfs_inode *ip);
 void xfs_filestream_deassociate(struct xfs_inode *ip);
+xfs_agnumber_t xfs_filestream_lookup_ag(struct xfs_inode *ip);
+int xfs_filestream_associate(struct xfs_inode *dip);
 int xfs_filestream_new_ag(struct xfs_bmalloca *ap, xfs_agnumber_t *agp);
 
-
-/* filestreams for the inode? */
 static inline int
 xfs_inode_is_filestream(
         struct xfs_inode        *ip)
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 3328320592a6..b9b531f7fa3d 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -846,9 +846,9 @@ xfs_ialloc(
 
         /* now we have set up the vfs inode we can associate the filestream */
         if (filestreams) {
-                error = xfs_filestream_associate(pip, ip);
-                if (error < 0)
-                        return -error;
+                error = xfs_filestream_associate(pip);
+                if (error)
+                        return error;
         }
 
         *ipp = ip;
@@ -1696,16 +1696,6 @@ xfs_release(
                 int truncated;
 
                 /*
-                 * If we are using filestreams, and we have an unlinked
-                 * file that we are processing the last close on, then nothing
-                 * will be able to reopen and write to this file. Purge this
-                 * inode from the filestreams cache so that it doesn't delay
-                 * teardown of the inode.
-                 */
-                if ((ip->i_d.di_nlink == 0) && xfs_inode_is_filestream(ip))
-                        xfs_filestream_deassociate(ip);
-
-                /*
                  * If we previously truncated this file and removed old data
                  * in the process, we want to initiate "early" writeout on
                  * the last close.  This is an attempt to combat the notorious
@@ -2661,13 +2651,7 @@ xfs_remove(
         if (error)
                 goto std_return;
 
-        /*
-         * If we are using filestreams, kill the stream association.
-         * If the file is still open it may get a new one but that
-         * will get killed on last close in xfs_close() so we don't
-         * have to worry about that.
-         */
-        if (!is_dir && link_zero && xfs_inode_is_filestream(ip))
+        if (is_dir && xfs_inode_is_filestream(ip))
                 xfs_filestream_deassociate(ip);
 
         return 0;