shrinker: convert superblock shrinkers to new API

Convert superblock shrinker to use the new count/scan API, and propagate
the API changes through to the filesystem callouts.  The filesystem
callouts already use a count/scan API, so it's just changing counters to
longs to match the VM API.

This requires the dentry and inode shrinker callouts to be converted to
the count/scan API.  This is mainly a mechanical change.

[glommer@openvz.org: use mult_frac for fractional proportions, build fixes]
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Glauber Costa <glommer@openvz.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Rientjes <rientjes@google.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: J. Bruce Fields <bfields@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 49 insertions, 31 deletions

diff --git a/fs/super.c b/fs/super.c
index 3c5318694ccd..8aa2660642b9 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -53,11 +53,15 @@ static char *sb_writers_name[SB_FREEZE_LEVELS] = {
  * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we
  * take a passive reference to the superblock to avoid this from occurring.
  */
-static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
+static unsigned long super_cache_scan(struct shrinker *shrink,
+                                      struct shrink_control *sc)
 {
         struct super_block *sb;
-        int     fs_objects = 0;
-        int     total_objects;
+        long    fs_objects = 0;
+        long    total_objects;
+        long    freed = 0;
+        long    dentries;
+        long    inodes;
 
         sb = container_of(shrink, struct super_block, s_shrink);
 
@@ -65,11 +69,11 @@ static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
          * Deadlock avoidance.  We may hold various FS locks, and we don't want
          * to recurse into the FS that called us in clear_inode() and friends..
          */
-        if (sc->nr_to_scan && !(sc->gfp_mask & __GFP_FS))
-                return -1;
+        if (!(sc->gfp_mask & __GFP_FS))
+                return SHRINK_STOP;
 
         if (!grab_super_passive(sb))
-                return -1;
+                return SHRINK_STOP;
 
         if (sb->s_op->nr_cached_objects)
                 fs_objects = sb->s_op->nr_cached_objects(sb);
@@ -77,33 +81,46 @@ static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
         total_objects = sb->s_nr_dentry_unused +
                         sb->s_nr_inodes_unused + fs_objects + 1;
 
-        if (sc->nr_to_scan) {
-                int     dentries;
-                int     inodes;
-
-                /* proportion the scan between the caches */
-                dentries = mult_frac(sc->nr_to_scan, sb->s_nr_dentry_unused,
-                                                        total_objects);
-                inodes = mult_frac(sc->nr_to_scan, sb->s_nr_inodes_unused,
-                                                        total_objects);
-                if (fs_objects)
-                        fs_objects = mult_frac(sc->nr_to_scan, fs_objects,
-                                                        total_objects);
-                /*
-                 * prune the dcache first as the icache is pinned by it, then
-                 * prune the icache, followed by the filesystem specific caches
-                 */
-                prune_dcache_sb(sb, dentries);
-                prune_icache_sb(sb, inodes);
+        /* proportion the scan between the caches */
+        dentries = mult_frac(sc->nr_to_scan, sb->s_nr_dentry_unused,
+                                                                total_objects);
+        inodes = mult_frac(sc->nr_to_scan, sb->s_nr_inodes_unused,
+                                                                total_objects);
 
-                if (fs_objects && sb->s_op->free_cached_objects) {
-                        sb->s_op->free_cached_objects(sb, fs_objects);
-                        fs_objects = sb->s_op->nr_cached_objects(sb);
-                }
-                total_objects = sb->s_nr_dentry_unused +
-                                sb->s_nr_inodes_unused + fs_objects;
+        /*
+         * prune the dcache first as the icache is pinned by it, then
+         * prune the icache, followed by the filesystem specific caches
+         */
+        freed = prune_dcache_sb(sb, dentries);
+        freed += prune_icache_sb(sb, inodes);
+
+        if (fs_objects) {
+                fs_objects = mult_frac(sc->nr_to_scan, fs_objects,
+                                                                total_objects);
+                freed += sb->s_op->free_cached_objects(sb, fs_objects);
         }
 
+        drop_super(sb);
+        return freed;
+}
+
+static unsigned long super_cache_count(struct shrinker *shrink,
+                                       struct shrink_control *sc)
+{
+        struct super_block *sb;
+        long    total_objects = 0;
+
+        sb = container_of(shrink, struct super_block, s_shrink);
+
+        if (!grab_super_passive(sb))
+                return 0;
+
+        if (sb->s_op && sb->s_op->nr_cached_objects)
+                total_objects = sb->s_op->nr_cached_objects(sb);
+
+        total_objects += sb->s_nr_dentry_unused;
+        total_objects += sb->s_nr_inodes_unused;
+
         total_objects = vfs_pressure_ratio(total_objects);
         drop_super(sb);
         return total_objects;
@@ -211,7 +228,8 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
                 s->cleancache_poolid = -1;
 
                 s->s_shrink.seeks = DEFAULT_SEEKS;
-                s->s_shrink.shrink = prune_super;
+                s->s_shrink.scan_objects = super_cache_scan;
+                s->s_shrink.count_objects = super_cache_count;
                 s->s_shrink.batch = 1024;
         }
 out: