xfs: rename xfs_sync.[ch] to xfs_icache.[ch]

xfs_sync.c now only contains inode reclaim functions and inode cache
iteration functions. It is not related to sync operations anymore.
Rename to xfs_icache.c to reflect it's contents and prepare for
consolidation with the other inode cache file that exists
(xfs_iget.c).

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 715 insertions, 0 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
new file mode 100644
index 000000000000..eba216f11d5e
--- /dev/null
+++ b/fs/xfs/xfs_icache.c
@@ -0,0 +1,715 @@
+/*
+ * Copyright (c) 2000-2005 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_fs.h"
+#include "xfs_types.h"
+#include "xfs_log.h"
+#include "xfs_log_priv.h"
+#include "xfs_inum.h"
+#include "xfs_trans.h"
+#include "xfs_trans_priv.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_mount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inode.h"
+#include "xfs_dinode.h"
+#include "xfs_error.h"
+#include "xfs_filestream.h"
+#include "xfs_vnodeops.h"
+#include "xfs_inode_item.h"
+#include "xfs_quota.h"
+#include "xfs_trace.h"
+#include "xfs_fsops.h"
+#include "xfs_icache.h"
+
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+
+/*
+ * The inode lookup is done in batches to keep the amount of lock traffic and
+ * radix tree lookups to a minimum. The batch size is a trade off between
+ * lookup reduction and stack usage. This is in the reclaim path, so we can't
+ * be too greedy.
+ */
+#define XFS_LOOKUP_BATCH        32
+
+STATIC int
+xfs_inode_ag_walk_grab(
+        struct xfs_inode        *ip)
+{
+        struct inode            *inode = VFS_I(ip);
+
+        ASSERT(rcu_read_lock_held());
+
+        /*
+         * check for stale RCU freed inode
+         *
+         * If the inode has been reallocated, it doesn't matter if it's not in
+         * the AG we are walking - we are walking for writeback, so if it
+         * passes all the "valid inode" checks and is dirty, then we'll write
+         * it back anyway.  If it has been reallocated and still being
+         * initialised, the XFS_INEW check below will catch it.
+         */
+        spin_lock(&ip->i_flags_lock);
+        if (!ip->i_ino)
+                goto out_unlock_noent;
+
+        /* avoid new or reclaimable inodes. Leave for reclaim code to flush */
+        if (__xfs_iflags_test(ip, XFS_INEW | XFS_IRECLAIMABLE | XFS_IRECLAIM))
+                goto out_unlock_noent;
+        spin_unlock(&ip->i_flags_lock);
+
+        /* nothing to sync during shutdown */
+        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
+                return EFSCORRUPTED;
+
+        /* If we can't grab the inode, it must on it's way to reclaim. */
+        if (!igrab(inode))
+                return ENOENT;
+
+        if (is_bad_inode(inode)) {
+                IRELE(ip);
+                return ENOENT;
+        }
+
+        /* inode is valid */
+        return 0;
+
+out_unlock_noent:
+        spin_unlock(&ip->i_flags_lock);
+        return ENOENT;
+}
+
+STATIC int
+xfs_inode_ag_walk(
+        struct xfs_mount        *mp,
+        struct xfs_perag        *pag,
+        int                     (*execute)(struct xfs_inode *ip,
+                                           struct xfs_perag *pag, int flags),
+        int                     flags)
+{
+        uint32_t                first_index;
+        int                     last_error = 0;
+        int                     skipped;
+        int                     done;
+        int                     nr_found;
+
+restart:
+        done = 0;
+        skipped = 0;
+        first_index = 0;
+        nr_found = 0;
+        do {
+                struct xfs_inode *batch[XFS_LOOKUP_BATCH];
+                int             error = 0;
+                int             i;
+
+                rcu_read_lock();
+                nr_found = radix_tree_gang_lookup(&pag->pag_ici_root,
+                                        (void **)batch, first_index,
+                                        XFS_LOOKUP_BATCH);
+                if (!nr_found) {
+                        rcu_read_unlock();
+                        break;
+                }
+
+                /*
+                 * Grab the inodes before we drop the lock. if we found
+                 * nothing, nr == 0 and the loop will be skipped.
+                 */
+                for (i = 0; i < nr_found; i++) {
+                        struct xfs_inode *ip = batch[i];
+
+                        if (done || xfs_inode_ag_walk_grab(ip))
+                                batch[i] = NULL;
+
+                        /*
+                         * Update the index for the next lookup. Catch
+                         * overflows into the next AG range which can occur if
+                         * we have inodes in the last block of the AG and we
+                         * are currently pointing to the last inode.
+                         *
+                         * Because we may see inodes that are from the wrong AG
+                         * due to RCU freeing and reallocation, only update the
+                         * index if it lies in this AG. It was a race that lead
+                         * us to see this inode, so another lookup from the
+                         * same index will not find it again.
+                         */
+                        if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno)
+                                continue;
+                        first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
+                        if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
+                                done = 1;
+                }
+
+                /* unlock now we've grabbed the inodes. */
+                rcu_read_unlock();
+
+                for (i = 0; i < nr_found; i++) {
+                        if (!batch[i])
+                                continue;
+                        error = execute(batch[i], pag, flags);
+                        IRELE(batch[i]);
+                        if (error == EAGAIN) {
+                                skipped++;
+                                continue;
+                        }
+                        if (error && last_error != EFSCORRUPTED)
+                                last_error = error;
+                }
+
+                /* bail out if the filesystem is corrupted.  */
+                if (error == EFSCORRUPTED)
+                        break;
+
+                cond_resched();
+
+        } while (nr_found && !done);
+
+        if (skipped) {
+                delay(1);
+                goto restart;
+        }
+        return last_error;
+}
+
+int
+xfs_inode_ag_iterator(
+        struct xfs_mount        *mp,
+        int                     (*execute)(struct xfs_inode *ip,
+                                           struct xfs_perag *pag, int flags),
+        int                     flags)
+{
+        struct xfs_perag        *pag;
+        int                     error = 0;
+        int                     last_error = 0;
+        xfs_agnumber_t          ag;
+
+        ag = 0;
+        while ((pag = xfs_perag_get(mp, ag))) {
+                ag = pag->pag_agno + 1;
+                error = xfs_inode_ag_walk(mp, pag, execute, flags);
+                xfs_perag_put(pag);
+                if (error) {
+                        last_error = error;
+                        if (error == EFSCORRUPTED)
+                                break;
+                }
+        }
+        return XFS_ERROR(last_error);
+}
+
+/*
+ * Queue a new inode reclaim pass if there are reclaimable inodes and there
+ * isn't a reclaim pass already in progress. By default it runs every 5s based
+ * on the xfs periodic sync default of 30s. Perhaps this should have it's own
+ * tunable, but that can be done if this method proves to be ineffective or too
+ * aggressive.
+ */
+static void
+xfs_reclaim_work_queue(
+        struct xfs_mount        *mp)
+{
+
+        rcu_read_lock();
+        if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+                queue_delayed_work(mp->m_reclaim_workqueue, &mp->m_reclaim_work,
+                        msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10));
+        }
+        rcu_read_unlock();
+}
+
+/*
+ * This is a fast pass over the inode cache to try to get reclaim moving on as
+ * many inodes as possible in a short period of time. It kicks itself every few
+ * seconds, as well as being kicked by the inode cache shrinker when memory
+ * goes low. It scans as quickly as possible avoiding locked inodes or those
+ * already being flushed, and once done schedules a future pass.
+ */
+void
+xfs_reclaim_worker(
+        struct work_struct *work)
+{
+        struct xfs_mount *mp = container_of(to_delayed_work(work),
+                                        struct xfs_mount, m_reclaim_work);
+
+        xfs_reclaim_inodes(mp, SYNC_TRYLOCK);
+        xfs_reclaim_work_queue(mp);
+}
+
+void
+__xfs_inode_set_reclaim_tag(
+        struct xfs_perag        *pag,
+        struct xfs_inode        *ip)
+{
+        radix_tree_tag_set(&pag->pag_ici_root,
+                           XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
+                           XFS_ICI_RECLAIM_TAG);
+
+        if (!pag->pag_ici_reclaimable) {
+                /* propagate the reclaim tag up into the perag radix tree */
+                spin_lock(&ip->i_mount->m_perag_lock);
+                radix_tree_tag_set(&ip->i_mount->m_perag_tree,
+                                XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+                                XFS_ICI_RECLAIM_TAG);
+                spin_unlock(&ip->i_mount->m_perag_lock);
+
+                /* schedule periodic background inode reclaim */
+                xfs_reclaim_work_queue(ip->i_mount);
+
+                trace_xfs_perag_set_reclaim(ip->i_mount, pag->pag_agno,
+                                                        -1, _RET_IP_);
+        }
+        pag->pag_ici_reclaimable++;
+}
+
+/*
+ * We set the inode flag atomically with the radix tree tag.
+ * Once we get tag lookups on the radix tree, this inode flag
+ * can go away.
+ */
+void
+xfs_inode_set_reclaim_tag(
+        xfs_inode_t     *ip)
+{
+        struct xfs_mount *mp = ip->i_mount;
+        struct xfs_perag *pag;
+
+        pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
+        spin_lock(&pag->pag_ici_lock);
+        spin_lock(&ip->i_flags_lock);
+        __xfs_inode_set_reclaim_tag(pag, ip);
+        __xfs_iflags_set(ip, XFS_IRECLAIMABLE);
+        spin_unlock(&ip->i_flags_lock);
+        spin_unlock(&pag->pag_ici_lock);
+        xfs_perag_put(pag);
+}
+
+STATIC void
+__xfs_inode_clear_reclaim(
+        xfs_perag_t     *pag,
+        xfs_inode_t     *ip)
+{
+        pag->pag_ici_reclaimable--;
+        if (!pag->pag_ici_reclaimable) {
+                /* clear the reclaim tag from the perag radix tree */
+                spin_lock(&ip->i_mount->m_perag_lock);
+                radix_tree_tag_clear(&ip->i_mount->m_perag_tree,
+                                XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
+                                XFS_ICI_RECLAIM_TAG);
+                spin_unlock(&ip->i_mount->m_perag_lock);
+                trace_xfs_perag_clear_reclaim(ip->i_mount, pag->pag_agno,
+                                                        -1, _RET_IP_);
+        }
+}
+
+void
+__xfs_inode_clear_reclaim_tag(
+        xfs_mount_t     *mp,
+        xfs_perag_t     *pag,
+        xfs_inode_t     *ip)
+{
+        radix_tree_tag_clear(&pag->pag_ici_root,
+                        XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
+        __xfs_inode_clear_reclaim(pag, ip);
+}
+
+/*
+ * Grab the inode for reclaim exclusively.
+ * Return 0 if we grabbed it, non-zero otherwise.
+ */
+STATIC int
+xfs_reclaim_inode_grab(
+        struct xfs_inode        *ip,
+        int                     flags)
+{
+        ASSERT(rcu_read_lock_held());
+
+        /* quick check for stale RCU freed inode */
+        if (!ip->i_ino)
+                return 1;
+
+        /*
+         * If we are asked for non-blocking operation, do unlocked checks to
+         * see if the inode already is being flushed or in reclaim to avoid
+         * lock traffic.
+         */
+        if ((flags & SYNC_TRYLOCK) &&
+            __xfs_iflags_test(ip, XFS_IFLOCK | XFS_IRECLAIM))
+                return 1;
+
+        /*
+         * The radix tree lock here protects a thread in xfs_iget from racing
+         * with us starting reclaim on the inode.  Once we have the
+         * XFS_IRECLAIM flag set it will not touch us.
+         *
+         * Due to RCU lookup, we may find inodes that have been freed and only
+         * have XFS_IRECLAIM set.  Indeed, we may see reallocated inodes that
+         * aren't candidates for reclaim at all, so we must check the
+         * XFS_IRECLAIMABLE is set first before proceeding to reclaim.
+         */
+        spin_lock(&ip->i_flags_lock);
+        if (!__xfs_iflags_test(ip, XFS_IRECLAIMABLE) ||
+            __xfs_iflags_test(ip, XFS_IRECLAIM)) {
+                /* not a reclaim candidate. */
+                spin_unlock(&ip->i_flags_lock);
+                return 1;
+        }
+        __xfs_iflags_set(ip, XFS_IRECLAIM);
+        spin_unlock(&ip->i_flags_lock);
+        return 0;
+}
+
+/*
+ * Inodes in different states need to be treated differently. The following
+ * table lists the inode states and the reclaim actions necessary:
+ *
+ *      inode state          iflush ret         required action
+ *      ---------------      ----------         ---------------
+ *      bad                     -               reclaim
+ *      shutdown                EIO             unpin and reclaim
+ *      clean, unpinned         0               reclaim
+ *      stale, unpinned         0               reclaim
+ *      clean, pinned(*)        0               requeue
+ *      stale, pinned           EAGAIN          requeue
+ *      dirty, async            -               requeue
+ *      dirty, sync             0               reclaim
+ *
+ * (*) dgc: I don't think the clean, pinned state is possible but it gets
+ * handled anyway given the order of checks implemented.
+ *
+ * Also, because we get the flush lock first, we know that any inode that has
+ * been flushed delwri has had the flush completed by the time we check that
+ * the inode is clean.
+ *
+ * Note that because the inode is flushed delayed write by AIL pushing, the
+ * flush lock may already be held here and waiting on it can result in very
+ * long latencies.  Hence for sync reclaims, where we wait on the flush lock,
+ * the caller should push the AIL first before trying to reclaim inodes to
+ * minimise the amount of time spent waiting.  For background relaim, we only
+ * bother to reclaim clean inodes anyway.
+ *
+ * Hence the order of actions after gaining the locks should be:
+ *      bad             => reclaim
+ *      shutdown        => unpin and reclaim
+ *      pinned, async   => requeue
+ *      pinned, sync    => unpin
+ *      stale           => reclaim
+ *      clean           => reclaim
+ *      dirty, async    => requeue
+ *      dirty, sync     => flush, wait and reclaim
+ */
+STATIC int
+xfs_reclaim_inode(
+        struct xfs_inode        *ip,
+        struct xfs_perag        *pag,
+        int                     sync_mode)
+{
+        struct xfs_buf          *bp = NULL;
+        int                     error;
+
+restart:
+        error = 0;
+        xfs_ilock(ip, XFS_ILOCK_EXCL);
+        if (!xfs_iflock_nowait(ip)) {
+                if (!(sync_mode & SYNC_WAIT))
+                        goto out;
+                xfs_iflock(ip);
+        }
+
+        if (is_bad_inode(VFS_I(ip)))
+                goto reclaim;
+        if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+                xfs_iunpin_wait(ip);
+                xfs_iflush_abort(ip, false);
+                goto reclaim;
+        }
+        if (xfs_ipincount(ip)) {
+                if (!(sync_mode & SYNC_WAIT))
+                        goto out_ifunlock;
+                xfs_iunpin_wait(ip);
+        }
+        if (xfs_iflags_test(ip, XFS_ISTALE))
+                goto reclaim;
+        if (xfs_inode_clean(ip))
+                goto reclaim;
+
+        /*
+         * Never flush out dirty data during non-blocking reclaim, as it would
+         * just contend with AIL pushing trying to do the same job.
+         */
+        if (!(sync_mode & SYNC_WAIT))
+                goto out_ifunlock;
+
+        /*
+         * Now we have an inode that needs flushing.
+         *
+         * Note that xfs_iflush will never block on the inode buffer lock, as
+         * xfs_ifree_cluster() can lock the inode buffer before it locks the
+         * ip->i_lock, and we are doing the exact opposite here.  As a result,
+         * doing a blocking xfs_imap_to_bp() to get the cluster buffer would
+         * result in an ABBA deadlock with xfs_ifree_cluster().
+         *
+         * As xfs_ifree_cluser() must gather all inodes that are active in the
+         * cache to mark them stale, if we hit this case we don't actually want
+         * to do IO here - we want the inode marked stale so we can simply
+         * reclaim it.  Hence if we get an EAGAIN error here,  just unlock the
+         * inode, back off and try again.  Hopefully the next pass through will
+         * see the stale flag set on the inode.
+         */
+        error = xfs_iflush(ip, &bp);
+        if (error == EAGAIN) {
+                xfs_iunlock(ip, XFS_ILOCK_EXCL);
+                /* backoff longer than in xfs_ifree_cluster */
+                delay(2);
+                goto restart;
+        }
+
+        if (!error) {
+                error = xfs_bwrite(bp);
+                xfs_buf_relse(bp);
+        }
+
+        xfs_iflock(ip);
+reclaim:
+        xfs_ifunlock(ip);
+        xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+        XFS_STATS_INC(xs_ig_reclaims);
+        /*
+         * Remove the inode from the per-AG radix tree.
+         *
+         * Because radix_tree_delete won't complain even if the item was never
+         * added to the tree assert that it's been there before to catch
+         * problems with the inode life time early on.
+         */
+        spin_lock(&pag->pag_ici_lock);
+        if (!radix_tree_delete(&pag->pag_ici_root,
+                                XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino)))
+                ASSERT(0);
+        __xfs_inode_clear_reclaim(pag, ip);
+        spin_unlock(&pag->pag_ici_lock);
+
+        /*
+         * Here we do an (almost) spurious inode lock in order to coordinate
+         * with inode cache radix tree lookups.  This is because the lookup
+         * can reference the inodes in the cache without taking references.
+         *
+         * We make that OK here by ensuring that we wait until the inode is
+         * unlocked after the lookup before we go ahead and free it.
+         */
+        xfs_ilock(ip, XFS_ILOCK_EXCL);
+        xfs_qm_dqdetach(ip);
+        xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+        xfs_inode_free(ip);
+        return error;
+
+out_ifunlock:
+        xfs_ifunlock(ip);
+out:
+        xfs_iflags_clear(ip, XFS_IRECLAIM);
+        xfs_iunlock(ip, XFS_ILOCK_EXCL);
+        /*
+         * We could return EAGAIN here to make reclaim rescan the inode tree in
+         * a short while. However, this just burns CPU time scanning the tree
+         * waiting for IO to complete and the reclaim work never goes back to
+         * the idle state. Instead, return 0 to let the next scheduled
+         * background reclaim attempt to reclaim the inode again.
+         */
+        return 0;
+}
+
+/*
+ * Walk the AGs and reclaim the inodes in them. Even if the filesystem is
+ * corrupted, we still want to try to reclaim all the inodes. If we don't,
+ * then a shut down during filesystem unmount reclaim walk leak all the
+ * unreclaimed inodes.
+ */
+int
+xfs_reclaim_inodes_ag(
+        struct xfs_mount        *mp,
+        int                     flags,
+        int                     *nr_to_scan)
+{
+        struct xfs_perag        *pag;
+        int                     error = 0;
+        int                     last_error = 0;
+        xfs_agnumber_t          ag;
+        int                     trylock = flags & SYNC_TRYLOCK;
+        int                     skipped;
+
+restart:
+        ag = 0;
+        skipped = 0;
+        while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
+                unsigned long   first_index = 0;
+                int             done = 0;
+                int             nr_found = 0;
+
+                ag = pag->pag_agno + 1;
+
+                if (trylock) {
+                        if (!mutex_trylock(&pag->pag_ici_reclaim_lock)) {
+                                skipped++;
+                                xfs_perag_put(pag);
+                                continue;
+                        }
+                        first_index = pag->pag_ici_reclaim_cursor;
+                } else
+                        mutex_lock(&pag->pag_ici_reclaim_lock);
+
+                do {
+                        struct xfs_inode *batch[XFS_LOOKUP_BATCH];
+                        int     i;
+
+                        rcu_read_lock();
+                        nr_found = radix_tree_gang_lookup_tag(
+                                        &pag->pag_ici_root,
+                                        (void **)batch, first_index,
+                                        XFS_LOOKUP_BATCH,
+                                        XFS_ICI_RECLAIM_TAG);
+                        if (!nr_found) {
+                                done = 1;
+                                rcu_read_unlock();
+                                break;
+                        }
+
+                        /*
+                         * Grab the inodes before we drop the lock. if we found
+                         * nothing, nr == 0 and the loop will be skipped.
+                         */
+                        for (i = 0; i < nr_found; i++) {
+                                struct xfs_inode *ip = batch[i];
+
+                                if (done || xfs_reclaim_inode_grab(ip, flags))
+                                        batch[i] = NULL;
+
+                                /*
+                                 * Update the index for the next lookup. Catch
+                                 * overflows into the next AG range which can
+                                 * occur if we have inodes in the last block of
+                                 * the AG and we are currently pointing to the
+                                 * last inode.
+                                 *
+                                 * Because we may see inodes that are from the
+                                 * wrong AG due to RCU freeing and
+                                 * reallocation, only update the index if it
+                                 * lies in this AG. It was a race that lead us
+                                 * to see this inode, so another lookup from
+                                 * the same index will not find it again.
+                                 */
+                                if (XFS_INO_TO_AGNO(mp, ip->i_ino) !=
+                                                                pag->pag_agno)
+                                        continue;
+                                first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
+                                if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
+                                        done = 1;
+                        }
+
+                        /* unlock now we've grabbed the inodes. */
+                        rcu_read_unlock();
+
+                        for (i = 0; i < nr_found; i++) {
+                                if (!batch[i])
+                                        continue;
+                                error = xfs_reclaim_inode(batch[i], pag, flags);
+                                if (error && last_error != EFSCORRUPTED)
+                                        last_error = error;
+                        }
+
+                        *nr_to_scan -= XFS_LOOKUP_BATCH;
+
+                        cond_resched();
+
+                } while (nr_found && !done && *nr_to_scan > 0);
+
+                if (trylock && !done)
+                        pag->pag_ici_reclaim_cursor = first_index;
+                else
+                        pag->pag_ici_reclaim_cursor = 0;
+                mutex_unlock(&pag->pag_ici_reclaim_lock);
+                xfs_perag_put(pag);
+        }
+
+        /*
+         * if we skipped any AG, and we still have scan count remaining, do
+         * another pass this time using blocking reclaim semantics (i.e
+         * waiting on the reclaim locks and ignoring the reclaim cursors). This
+         * ensure that when we get more reclaimers than AGs we block rather
+         * than spin trying to execute reclaim.
+         */
+        if (skipped && (flags & SYNC_WAIT) && *nr_to_scan > 0) {
+                trylock = 0;
+                goto restart;
+        }
+        return XFS_ERROR(last_error);
+}
+
+int
+xfs_reclaim_inodes(
+        xfs_mount_t     *mp,
+        int             mode)
+{
+        int             nr_to_scan = INT_MAX;
+
+        return xfs_reclaim_inodes_ag(mp, mode, &nr_to_scan);
+}
+
+/*
+ * Scan a certain number of inodes for reclaim.
+ *
+ * When called we make sure that there is a background (fast) inode reclaim in
+ * progress, while we will throttle the speed of reclaim via doing synchronous
+ * reclaim of inodes. That means if we come across dirty inodes, we wait for
+ * them to be cleaned, which we hope will not be very long due to the
+ * background walker having already kicked the IO off on those dirty inodes.
+ */
+void
+xfs_reclaim_inodes_nr(
+        struct xfs_mount        *mp,
+        int                     nr_to_scan)
+{
+        /* kick background reclaimer and push the AIL */
+        xfs_reclaim_work_queue(mp);
+        xfs_ail_push_all(mp->m_ail);
+
+        xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK | SYNC_WAIT, &nr_to_scan);
+}
+
+/*
+ * Return the number of reclaimable inodes in the filesystem for
+ * the shrinker to determine how much to reclaim.
+ */
+int
+xfs_reclaim_inodes_count(
+        struct xfs_mount        *mp)
+{
+        struct xfs_perag        *pag;
+        xfs_agnumber_t          ag = 0;
+        int                     reclaimable = 0;
+
+        while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
+                ag = pag->pag_agno + 1;
+                reclaimable += pag->pag_ici_reclaimable;
+                xfs_perag_put(pag);
+        }
+        return reclaimable;
+}
+