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[PATCH 5/5] xfs: make use of new shrinker callout

To: linux-kernel@xxxxxxxxxxxxxxx
Subject: [PATCH 5/5] xfs: make use of new shrinker callout
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 25 May 2010 18:53:08 +1000
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <1274777588-21494-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1274777588-21494-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

Convert the inode reclaim shrinker to use the new per-sb shrinker
operations.  This fixes a bunch of lockdep warnings about the
xfs_mount_list_lock being taken in different reclaim contexts by
removing it, and allows the reclaim to be proportioned across
filesystems with no extra code.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/linux-2.6/xfs_super.c   |   23 ++++++--
 fs/xfs/linux-2.6/xfs_sync.c    |  124 +++++++++++-----------------------------
 fs/xfs/linux-2.6/xfs_sync.h    |   16 +++--
 fs/xfs/quota/xfs_qm_syscalls.c |    2 +-
 fs/xfs/xfs_mount.h             |    1 -
 5 files changed, 61 insertions(+), 105 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index f24dbe5..b59886a 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1212,7 +1212,6 @@ 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);
@@ -1626,8 +1625,6 @@ xfs_fs_fill_super(
        if (error)
                goto fail_vnrele;
 
-       xfs_inode_shrinker_register(mp);
-
        kfree(mtpt);
        return 0;
 
@@ -1681,6 +1678,22 @@ xfs_fs_get_sb(
                           mnt);
 }
 
+static int
+xfs_fs_nr_cached_objects(
+       struct super_block      *sb)
+{
+       return xfs_reclaim_inodes_count(XFS_M(sb));
+}
+
+static int
+xfs_fs_free_cached_objects(
+       struct super_block      *sb,
+       int                     nr_to_scan)
+{
+       xfs_reclaim_inodes_nr(XFS_M(sb), 0, nr_to_scan);
+       return 0;
+}
+
 static const struct super_operations xfs_super_operations = {
        .alloc_inode            = xfs_fs_alloc_inode,
        .destroy_inode          = xfs_fs_destroy_inode,
@@ -1694,6 +1707,8 @@ static const struct super_operations xfs_super_operations 
= {
        .statfs                 = xfs_fs_statfs,
        .remount_fs             = xfs_fs_remount,
        .show_options           = xfs_fs_show_options,
+       .nr_cached_objects      = xfs_fs_nr_cached_objects,
+       .free_cached_objects    = xfs_fs_free_cached_objects,
 };
 
 static struct file_system_type xfs_fs_type = {
@@ -1873,7 +1888,6 @@ init_xfs_fs(void)
                goto out_cleanup_procfs;
 
        vfs_initquota();
-       xfs_inode_shrinker_init();
 
        error = register_filesystem(&xfs_fs_type);
        if (error)
@@ -1901,7 +1915,6 @@ 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 c881a0c..6d74a0d 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -137,7 +137,7 @@ restart:
 
        } while ((*nr_to_scan)--);
 
-       if (skipped) {
+       if (skipped && *nr_to_scan > 0) {
                delay(1);
                goto restart;
        }
@@ -152,14 +152,14 @@ xfs_inode_ag_iterator(
        int                     flags,
        int                     tag,
        int                     exclusive,
-       int                     *nr_to_scan)
+       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;
+       if (nr_to_scan <= 0)
+               nr_to_scan = INT_MAX;
        for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
                struct xfs_perag        *pag;
 
@@ -169,18 +169,16 @@ xfs_inode_ag_iterator(
                        continue;
                }
                error = xfs_inode_ag_walk(mp, pag, execute, flags, tag,
-                                               exclusive, &nr);
+                                               exclusive, &nr_to_scan);
                xfs_perag_put(pag);
                if (error) {
                        last_error = error;
                        if (error == EFSCORRUPTED)
                                break;
                }
-               if (nr <= 0)
+               if (nr_to_scan <= 0)
                        break;
        }
-       if (nr_to_scan)
-               *nr_to_scan = nr;
        return XFS_ERROR(last_error);
 }
 
@@ -299,7 +297,7 @@ 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, NULL);
+                                     XFS_ICI_NO_TAG, 0, 0);
        if (error)
                return XFS_ERROR(error);
 
@@ -318,7 +316,7 @@ xfs_sync_attr(
        ASSERT((flags & ~SYNC_WAIT) == 0);
 
        return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags,
-                                    XFS_ICI_NO_TAG, 0, NULL);
+                                    XFS_ICI_NO_TAG, 0, 0);
 }
 
 STATIC int
@@ -821,100 +819,44 @@ reclaim:
 
 }
 
+/*
+ * Scan a certain number of inodes for reclaim. nr_to_scan <= 0 means reclaim
+ * every inode that has the reclaim tag set.
+ */
 int
-xfs_reclaim_inodes(
+xfs_reclaim_inodes_nr(
        xfs_mount_t     *mp,
-       int             mode)
+       int             mode,
+       int             nr_to_scan)
 {
        return xfs_inode_ag_iterator(mp, xfs_reclaim_inode, mode,
-                                       XFS_ICI_RECLAIM_TAG, 1, NULL);
+                                       XFS_ICI_RECLAIM_TAG, 1, nr_to_scan);
 }
 
 /*
- * Shrinker infrastructure.
+ * Return the number of reclaimable inodes in the filesystem for
+ * the shrinker to determine how much to reclaim.
  *
- * 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.
+ * Because the inode cache may not have any reclaimable inodes in it, but will
+ * be populated as part of the higher level cleaning, we need to count all
+ * those inodes as reclaimable here as well.
  */
-static LIST_HEAD(xfs_mount_list);
-static struct rw_semaphore xfs_mount_list_lock;
-
-static int
-xfs_reclaim_inode_shrink(
-       struct shrinker *shrink,
-       int             nr_to_scan,
-       gfp_t           gfp_mask)
+int
+xfs_reclaim_inodes_count(
+       xfs_mount_t     *mp)
 {
-       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++) {
+       xfs_agnumber_t          ag;
+       int                     reclaimable = 0;
 
-                       pag = xfs_perag_get(mp, ag);
-                       if (!pag->pag_ici_init) {
-                               xfs_perag_put(pag);
-                               continue;
-                       }
-                       reclaimable += pag->pag_ici_reclaimable;
+       for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
+               struct xfs_perag *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);
+       return reclaimable + mp->m_super->s_nr_inodes_unused;
 }
 
-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 cdcbaac..c55f645 100644
--- a/fs/xfs/linux-2.6/xfs_sync.h
+++ b/fs/xfs/linux-2.6/xfs_sync.h
@@ -43,7 +43,14 @@ void xfs_quiesce_attr(struct xfs_mount *mp);
 
 void xfs_flush_inodes(struct xfs_inode *ip);
 
-int xfs_reclaim_inodes(struct xfs_mount *mp, int mode);
+int xfs_reclaim_inodes_count(struct xfs_mount *mp);
+int xfs_reclaim_inodes_nr(struct xfs_mount *mp, int mode, int nr_to_scan);
+
+static inline int
+xfs_reclaim_inodes(struct xfs_mount *mp, int mode)
+{
+       return xfs_reclaim_inodes_nr(mp, mode, 0);
+}
 
 void xfs_inode_set_reclaim_tag(struct xfs_inode *ip);
 void __xfs_inode_set_reclaim_tag(struct xfs_perag *pag, struct xfs_inode *ip);
@@ -53,11 +60,6 @@ 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 *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);
+       int flags, int tag, int write_lock, int nr_to_scan);
 
 #endif
diff --git a/fs/xfs/quota/xfs_qm_syscalls.c b/fs/xfs/quota/xfs_qm_syscalls.c
index 92b002f..f5b0e4e 100644
--- a/fs/xfs/quota/xfs_qm_syscalls.c
+++ b/fs/xfs/quota/xfs_qm_syscalls.c
@@ -894,7 +894,7 @@ xfs_qm_dqrele_all_inodes(
 {
        ASSERT(mp->m_quotainfo);
        xfs_inode_ag_iterator(mp, xfs_dqrele_inode, flags,
-                               XFS_ICI_NO_TAG, 0, NULL);
+                               XFS_ICI_NO_TAG, 0, 0);
 }
 
 /*------------------------------------------------------------------------*/
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 9ff48a1..4fa0bc7 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -259,7 +259,6 @@ typedef struct xfs_mount {
        wait_queue_head_t       m_wait_single_sync_task;
        __int64_t               m_update_flags; /* sb flags we need to update
                                                   on the next remount,rw */
-       struct list_head        m_mplist;       /* inode shrinker mount list */
 } xfs_mount_t;
 
 /*
-- 
1.5.6.5

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