superblock: add filesystem shrinker operations
Now we have a per-superblock shrinker implementation, we can add a
filesystem specific callout to it to allow filesystem internal
caches to be shrunk by the superblock shrinker.
Rather than perpetuate the multipurpose shrinker callback API (i.e.
nr_to_scan == 0 meaning "tell me how many objects freeable in the
cache), two operations will be added. The first will return the
number of objects that are freeable, the second is the actual
shrinker call.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/super.c b/fs/super.c
index 37a7541..5101f05 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -48,7 +48,8 @@
static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
{
struct super_block *sb;
- int count;
+ int fs_objects = 0;
+ int total_objects;
sb = container_of(shrink, struct super_block, s_shrink);
@@ -62,22 +63,42 @@
if (!grab_super_passive(sb))
return -1;
+ if (sb->s_op && sb->s_op->nr_cached_objects)
+ fs_objects = sb->s_op->nr_cached_objects(sb);
+
+ total_objects = sb->s_nr_dentry_unused +
+ sb->s_nr_inodes_unused + fs_objects + 1;
+
if (sc->nr_to_scan) {
- /* proportion the scan between the two caches */
- int total;
+ int dentries;
+ int inodes;
- total = sb->s_nr_dentry_unused + sb->s_nr_inodes_unused + 1;
- count = (sc->nr_to_scan * sb->s_nr_dentry_unused) / total;
+ /* proportion the scan between the caches */
+ dentries = (sc->nr_to_scan * sb->s_nr_dentry_unused) /
+ total_objects;
+ inodes = (sc->nr_to_scan * sb->s_nr_inodes_unused) /
+ total_objects;
+ if (fs_objects)
+ fs_objects = (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);
- /* prune dcache first as icache is pinned by it */
- prune_dcache_sb(sb, count);
- prune_icache_sb(sb, sc->nr_to_scan - count);
+ 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;
}
- count = ((sb->s_nr_dentry_unused + sb->s_nr_inodes_unused) / 100)
- * sysctl_vfs_cache_pressure;
+ total_objects = (total_objects / 100) * sysctl_vfs_cache_pressure;
drop_super(sb);
- return count;
+ return total_objects;
}
/**