3 files changed, 116 insertions, 8 deletions

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 52e06b487ced..29f1edca76de 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1209,6 +1209,7 @@ xfs_fs_put_super(
 
         xfs_unmountfs(mp);
         xfs_freesb(mp);
+        xfs_inode_shrinker_unregister(mp);
         xfs_icsb_destroy_counters(mp);
         xfs_close_devices(mp);
         xfs_dmops_put(mp);
@@ -1622,6 +1623,8 @@ xfs_fs_fill_super(
         if (error)
                 goto fail_vnrele;
 
+        xfs_inode_shrinker_register(mp);
+
         kfree(mtpt);
         return 0;
 
@@ -1867,6 +1870,7 @@ init_xfs_fs(void)
                 goto out_cleanup_procfs;
 
         vfs_initquota();
+        xfs_inode_shrinker_init();
 
         error = register_filesystem(&xfs_fs_type);
         if (error)
@@ -1894,6 +1898,7 @@ exit_xfs_fs(void)
 {
         vfs_exitquota();
         unregister_filesystem(&xfs_fs_type);
+        xfs_inode_shrinker_destroy();
         xfs_sysctl_unregister();
         xfs_cleanup_procfs();
         xfs_buf_terminate();
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index fd9698215759..a427c638d909 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -95,7 +95,8 @@ xfs_inode_ag_walk(
                                            struct xfs_perag *pag, int flags),
         int                     flags,
         int                     tag,
-        int                     exclusive)
+        int                     exclusive,
+        int                     *nr_to_scan)
 {
         uint32_t                first_index;
         int                     last_error = 0;
@@ -134,7 +135,7 @@ restart:
                 if (error == EFSCORRUPTED)
                         break;
 
-        } while (1);
+        } while ((*nr_to_scan)--);
 
         if (skipped) {
                 delay(1);
@@ -150,12 +151,15 @@ xfs_inode_ag_iterator(
                                            struct xfs_perag *pag, int flags),
         int                     flags,
         int                     tag,
-        int                     exclusive)
+        int                     exclusive,
+        int                     *nr_to_scan)
 {
         int                     error = 0;
         int                     last_error = 0;
         xfs_agnumber_t          ag;
+        int                     nr;
 
+        nr = nr_to_scan ? *nr_to_scan : INT_MAX;
         for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
                 struct xfs_perag        *pag;
 
@@ -165,14 +169,18 @@ xfs_inode_ag_iterator(
                         continue;
                 }
                 error = xfs_inode_ag_walk(mp, pag, execute, flags, tag,
-                                                exclusive);
+                                                exclusive, &nr);
                 xfs_perag_put(pag);
                 if (error) {
                         last_error = error;
                         if (error == EFSCORRUPTED)
                                 break;
                 }
+                if (nr <= 0)
+                        break;
         }
+        if (nr_to_scan)
+                *nr_to_scan = nr;
         return XFS_ERROR(last_error);
 }
 
@@ -291,7 +299,7 @@ xfs_sync_data(
         ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT)) == 0);
 
         error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags,
-                                      XFS_ICI_NO_TAG, 0);
+                                      XFS_ICI_NO_TAG, 0, NULL);
         if (error)
                 return XFS_ERROR(error);
 
@@ -310,7 +318,7 @@ xfs_sync_attr(
         ASSERT((flags & ~SYNC_WAIT) == 0);
 
         return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags,
-                                     XFS_ICI_NO_TAG, 0);
+                                     XFS_ICI_NO_TAG, 0, NULL);
 }
 
 STATIC int
@@ -673,6 +681,7 @@ __xfs_inode_set_reclaim_tag(
         radix_tree_tag_set(&pag->pag_ici_root,
                            XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
                            XFS_ICI_RECLAIM_TAG);
+        pag->pag_ici_reclaimable++;
 }
 
 /*
@@ -705,6 +714,7 @@ __xfs_inode_clear_reclaim_tag(
 {
         radix_tree_tag_clear(&pag->pag_ici_root,
                         XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
+        pag->pag_ici_reclaimable--;
 }
 
 /*
@@ -854,5 +864,93 @@ xfs_reclaim_inodes(
         int             mode)
 {
         return xfs_inode_ag_iterator(mp, xfs_reclaim_inode, mode,
-                                        XFS_ICI_RECLAIM_TAG, 1);
+                                        XFS_ICI_RECLAIM_TAG, 1, NULL);
+}
+
+/*
+ * Shrinker infrastructure.
+ *
+ * This is all far more complex than it needs to be. It adds a global list of
+ * mounts because the shrinkers can only call a global context. We need to make
+ * the shrinkers pass a context to avoid the need for global state.
+ */
+static LIST_HEAD(xfs_mount_list);
+static struct rw_semaphore xfs_mount_list_lock;
+
+static int
+xfs_reclaim_inode_shrink(
+        int             nr_to_scan,
+        gfp_t           gfp_mask)
+{
+        struct xfs_mount *mp;
+        struct xfs_perag *pag;
+        xfs_agnumber_t  ag;
+        int             reclaimable = 0;
+
+        if (nr_to_scan) {
+                if (!(gfp_mask & __GFP_FS))
+                        return -1;
+
+                down_read(&xfs_mount_list_lock);
+                list_for_each_entry(mp, &xfs_mount_list, m_mplist) {
+                        xfs_inode_ag_iterator(mp, xfs_reclaim_inode, 0,
+                                        XFS_ICI_RECLAIM_TAG, 1, &nr_to_scan);
+                        if (nr_to_scan <= 0)
+                                break;
+                }
+                up_read(&xfs_mount_list_lock);
+        }
+
+        down_read(&xfs_mount_list_lock);
+        list_for_each_entry(mp, &xfs_mount_list, m_mplist) {
+                for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
+
+                        pag = xfs_perag_get(mp, ag);
+                        if (!pag->pag_ici_init) {
+                                xfs_perag_put(pag);
+                                continue;
+                        }
+                        reclaimable += pag->pag_ici_reclaimable;
+                        xfs_perag_put(pag);
+                }
+        }
+        up_read(&xfs_mount_list_lock);
+        return reclaimable;
+}
+
+static struct shrinker xfs_inode_shrinker = {
+        .shrink = xfs_reclaim_inode_shrink,
+        .seeks = DEFAULT_SEEKS,
+};
+
+void __init
+xfs_inode_shrinker_init(void)
+{
+        init_rwsem(&xfs_mount_list_lock);
+        register_shrinker(&xfs_inode_shrinker);
+}
+
+void
+xfs_inode_shrinker_destroy(void)
+{
+        ASSERT(list_empty(&xfs_mount_list));
+        unregister_shrinker(&xfs_inode_shrinker);
+}
+
+void
+xfs_inode_shrinker_register(
+        struct xfs_mount        *mp)
+{
+        down_write(&xfs_mount_list_lock);
+        list_add_tail(&mp->m_mplist, &xfs_mount_list);
+        up_write(&xfs_mount_list_lock);
+}
+
+void
+xfs_inode_shrinker_unregister(
+        struct xfs_mount        *mp)
+{
+        down_write(&xfs_mount_list_lock);
+        list_del(&mp->m_mplist);
+        up_write(&xfs_mount_list_lock);
 }
diff --git a/fs/xfs/linux-2.6/xfs_sync.h b/fs/xfs/linux-2.6/xfs_sync.h
index d480c346cabb..cdcbaaca9880 100644
--- a/fs/xfs/linux-2.6/xfs_sync.h
+++ b/fs/xfs/linux-2.6/xfs_sync.h
@@ -53,6 +53,11 @@ void __xfs_inode_clear_reclaim_tag(struct xfs_mount *mp, struct xfs_perag *pag,
 int xfs_sync_inode_valid(struct xfs_inode *ip, struct xfs_perag *pag);
 int xfs_inode_ag_iterator(struct xfs_mount *mp,
         int (*execute)(struct xfs_inode *ip, struct xfs_perag *pag, int flags),
-        int flags, int tag, int write_lock);
+        int flags, int tag, int write_lock, int *nr_to_scan);
+
+void xfs_inode_shrinker_init(void);
+void xfs_inode_shrinker_destroy(void);
+void xfs_inode_shrinker_register(struct xfs_mount *mp);
+void xfs_inode_shrinker_unregister(struct xfs_mount *mp);
 
 #endif