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 3c5318694cc..8aa2660642b 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: