xfs: add background scanning to clear eofblocks inodes

Create a new mount workqueue and delayed_work to enable background
scanning and freeing of eofblocks inodes. The scanner kicks in once
speculative preallocation occurs and stops requeueing itself when
no eofblocks inodes exist.

The scan interval is based on the new
'speculative_prealloc_lifetime' tunable (default to 5m). The
background scanner performs unfiltered, best effort scans (which
skips inodes under lock contention or with a dirty cache mapping).

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

9 files changed, 58 insertions, 1 deletions

diff --git a/fs/xfs/xfs_globals.c b/fs/xfs/xfs_globals.c
index 76e81cff70b9..5399ef222dd7 100644
--- a/fs/xfs/xfs_globals.c
+++ b/fs/xfs/xfs_globals.c
@@ -21,7 +21,8 @@
 /*
  * Tunable XFS parameters.  xfs_params is required even when CONFIG_SYSCTL=n,
  * other XFS code uses these values.  Times are measured in centisecs (i.e.
- * 100ths of a second).
+ * 100ths of a second) with the exception of eofb_timer, which is measured in
+ * seconds.
  */
 xfs_param_t xfs_params = {
                           /*    MIN             DFLT            MAX     */
@@ -40,4 +41,5 @@ xfs_param_t xfs_params = {
         .rotorstep      = {     1,              1,              255     },
         .inherit_nodfrg = {     0,              1,              1       },
         .fstrm_timer    = {     1,              30*100,         3600*100},
+        .eofb_timer     = {     1,              300,            3600*24},
 };
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 906e6dcd2c55..96e344e3e927 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -615,6 +615,32 @@ restart:
         return last_error;
 }
 
+/*
+ * Background scanning to trim post-EOF preallocated space. This is queued
+ * based on the 'background_prealloc_discard_period' tunable (5m by default).
+ */
+STATIC void
+xfs_queue_eofblocks(
+        struct xfs_mount *mp)
+{
+        rcu_read_lock();
+        if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_EOFBLOCKS_TAG))
+                queue_delayed_work(mp->m_eofblocks_workqueue,
+                                   &mp->m_eofblocks_work,
+                                   msecs_to_jiffies(xfs_eofb_secs * 1000));
+        rcu_read_unlock();
+}
+
+void
+xfs_eofblocks_worker(
+        struct work_struct *work)
+{
+        struct xfs_mount *mp = container_of(to_delayed_work(work),
+                                struct xfs_mount, m_eofblocks_work);
+        xfs_icache_free_eofblocks(mp, NULL);
+        xfs_queue_eofblocks(mp);
+}
+
 int
 xfs_inode_ag_iterator(
         struct xfs_mount        *mp,
@@ -1273,6 +1299,9 @@ xfs_inode_set_eofblocks_tag(
                                    XFS_ICI_EOFBLOCKS_TAG);
                 spin_unlock(&ip->i_mount->m_perag_lock);
 
+                /* kick off background trimming */
+                xfs_queue_eofblocks(ip->i_mount);
+
                 trace_xfs_perag_set_eofblocks(ip->i_mount, pag->pag_agno,
                                               -1, _RET_IP_);
         }
diff --git a/fs/xfs/xfs_icache.h b/fs/xfs/xfs_icache.h
index 4934a77024cf..e0f138c70a2f 100644
--- a/fs/xfs/xfs_icache.h
+++ b/fs/xfs/xfs_icache.h
@@ -38,6 +38,7 @@ void xfs_inode_set_reclaim_tag(struct xfs_inode *ip);
 void xfs_inode_set_eofblocks_tag(struct xfs_inode *ip);
 void xfs_inode_clear_eofblocks_tag(struct xfs_inode *ip);
 int xfs_icache_free_eofblocks(struct xfs_mount *, struct xfs_eofblocks *);
+void xfs_eofblocks_worker(struct work_struct *);
 
 int xfs_sync_inode_grab(struct xfs_inode *ip);
 int xfs_inode_ag_iterator(struct xfs_mount *mp,
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index 828662f70d64..0a134ca5211c 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -118,6 +118,7 @@
 #define xfs_rotorstep           xfs_params.rotorstep.val
 #define xfs_inherit_nodefrag    xfs_params.inherit_nodfrg.val
 #define xfs_fstrm_centisecs     xfs_params.fstrm_timer.val
+#define xfs_eofb_secs           xfs_params.eofb_timer.val
 
 #define current_cpu()           (raw_smp_processor_id())
 #define current_pid()           (current->pid)
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 6f1c997704cd..41ae7e1590f5 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1428,6 +1428,8 @@ xfs_unmountfs(
         __uint64_t              resblks;
         int                     error;
 
+        cancel_delayed_work_sync(&mp->m_eofblocks_work);
+
         xfs_qm_unmount_quotas(mp);
         xfs_rtunmount_inodes(mp);
         IRELE(mp->m_rootip);
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index a631ca3b9065..dc306a09f56f 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -196,6 +196,8 @@ typedef struct xfs_mount {
 #endif
         struct xfs_mru_cache    *m_filestream;  /* per-mount filestream data */
         struct delayed_work     m_reclaim_work; /* background inode reclaim */
+        struct delayed_work     m_eofblocks_work; /* background eof blocks
+                                                     trimming */
         __int64_t               m_update_flags; /* sb flags we need to update
                                                    on the next remount,rw */
         struct shrinker         m_inode_shrink; /* inode reclaim shrinker */
@@ -207,6 +209,7 @@ typedef struct xfs_mount {
         struct workqueue_struct *m_cil_workqueue;
         struct workqueue_struct *m_reclaim_workqueue;
         struct workqueue_struct *m_log_workqueue;
+        struct workqueue_struct *m_eofblocks_workqueue;
 } xfs_mount_t;
 
 /*
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 3d9ea947e9f8..ab8839b26272 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -874,8 +874,15 @@ xfs_init_mount_workqueues(
         if (!mp->m_log_workqueue)
                 goto out_destroy_reclaim;
 
+        mp->m_eofblocks_workqueue = alloc_workqueue("xfs-eofblocks/%s",
+                        WQ_NON_REENTRANT, 0, mp->m_fsname);
+        if (!mp->m_eofblocks_workqueue)
+                goto out_destroy_log;
+
         return 0;
 
+out_destroy_log:
+        destroy_workqueue(mp->m_log_workqueue);
 out_destroy_reclaim:
         destroy_workqueue(mp->m_reclaim_workqueue);
 out_destroy_cil:
@@ -892,6 +899,7 @@ STATIC void
 xfs_destroy_mount_workqueues(
         struct xfs_mount        *mp)
 {
+        destroy_workqueue(mp->m_eofblocks_workqueue);
         destroy_workqueue(mp->m_log_workqueue);
         destroy_workqueue(mp->m_reclaim_workqueue);
         destroy_workqueue(mp->m_cil_workqueue);
@@ -1393,6 +1401,7 @@ xfs_fs_fill_super(
         mutex_init(&mp->m_growlock);
         atomic_set(&mp->m_active_trans, 0);
         INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker);
+        INIT_DELAYED_WORK(&mp->m_eofblocks_work, xfs_eofblocks_worker);
 
         mp->m_super = sb;
         sb->s_fs_info = mp;
diff --git a/fs/xfs/xfs_sysctl.c b/fs/xfs/xfs_sysctl.c
index ee2d2adaa438..2801b5ce6cdb 100644
--- a/fs/xfs/xfs_sysctl.c
+++ b/fs/xfs/xfs_sysctl.c
@@ -202,6 +202,15 @@ static ctl_table xfs_table[] = {
                 .extra1         = &xfs_params.fstrm_timer.min,
                 .extra2         = &xfs_params.fstrm_timer.max,
         },
+        {
+                .procname       = "speculative_prealloc_lifetime",
+                .data           = &xfs_params.eofb_timer.val,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &xfs_params.eofb_timer.min,
+                .extra2         = &xfs_params.eofb_timer.max,
+        },
         /* please keep this the last entry */
 #ifdef CONFIG_PROC_FS
         {
diff --git a/fs/xfs/xfs_sysctl.h b/fs/xfs/xfs_sysctl.h
index b9937d450f8e..bd8e157c20ef 100644
--- a/fs/xfs/xfs_sysctl.h
+++ b/fs/xfs/xfs_sysctl.h
@@ -47,6 +47,7 @@ typedef struct xfs_param {
         xfs_sysctl_val_t rotorstep;     /* inode32 AG rotoring control knob */
         xfs_sysctl_val_t inherit_nodfrg;/* Inherit the "nodefrag" inode flag. */
         xfs_sysctl_val_t fstrm_timer;   /* Filestream dir-AG assoc'n timeout. */
+        xfs_sysctl_val_t eofb_timer;    /* Interval between eofb scan wakeups */
 } xfs_param_t;
 
 /*