dcache: allocate external names from reclaimable kmalloc caches

We can use the newly introduced kmalloc-reclaimable-X caches, to allocate
external names in dcache, which will take care of the proper accounting
automatically, and also improve anti-fragmentation page grouping.

This effectively reverts commit 1a2ebe8410cb ("dcache: account external
names as indirectly reclaimable memory") and instead passes
__GFP_RECLAIMABLE to kmalloc().  The accounting thus moves from
NR_INDIRECTLY_RECLAIMABLE_BYTES to NR_SLAB_RECLAIMABLE, which is also
considered in MemAvailable calculation and overcommit decisions.

Link: http://lkml.kernel.org/r/20180731090649.16028-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/dcache.c b/fs/dcache.c
index 2e7e8d85e9b408a2296ca3d2510a2815dc78067f..c2e443fb76ae85bd22973a888c785e524de1f41a 100644 (file)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -257,24 +257,10 @@ static void __d_free(struct rcu_head *head)
        kmem_cache_free(dentry_cache, dentry); 
 }
 
-static void __d_free_external_name(struct rcu_head *head)
-{
-       struct external_name *name = container_of(head, struct external_name,
-                                                 u.head);
-
-       mod_node_page_state(page_pgdat(virt_to_page(name)),
-                           NR_INDIRECTLY_RECLAIMABLE_BYTES,
-                           -ksize(name));
-
-       kfree(name);
-}
-
 static void __d_free_external(struct rcu_head *head)
 {
        struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
-
-       __d_free_external_name(&external_name(dentry)->u.head);
-
+       kfree(external_name(dentry));
        kmem_cache_free(dentry_cache, dentry);
 }
 
@@ -306,7 +292,7 @@ void release_dentry_name_snapshot(struct name_snapshot *name)
                struct external_name *p;
                p = container_of(name->name, struct external_name, name[0]);
                if (unlikely(atomic_dec_and_test(&p->u.count)))
-                       call_rcu(&p->u.head, __d_free_external_name);
+                       kfree_rcu(p, u.head);
        }
 }
 EXPORT_SYMBOL(release_dentry_name_snapshot);
@@ -1606,7 +1592,6 @@ EXPORT_SYMBOL(d_invalidate);
  
 struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 {
-       struct external_name *ext = NULL;
        struct dentry *dentry;
        char *dname;
        int err;
@@ -1627,14 +1612,15 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
                dname = dentry->d_iname;
        } else if (name->len > DNAME_INLINE_LEN-1) {
                size_t size = offsetof(struct external_name, name[1]);
-
-               ext = kmalloc(size + name->len, GFP_KERNEL_ACCOUNT);
-               if (!ext) {
+               struct external_name *p = kmalloc(size + name->len,
+                                                 GFP_KERNEL_ACCOUNT |
+                                                 __GFP_RECLAIMABLE);
+               if (!p) {
                        kmem_cache_free(dentry_cache, dentry); 
                        return NULL;
                }
-               atomic_set(&ext->u.count, 1);
-               dname = ext->name;
+               atomic_set(&p->u.count, 1);
+               dname = p->name;
        } else  {
                dname = dentry->d_iname;
        }       
@@ -1673,12 +1659,6 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
                }
        }
 
-       if (unlikely(ext)) {
-               pg_data_t *pgdat = page_pgdat(virt_to_page(ext));
-               mod_node_page_state(pgdat, NR_INDIRECTLY_RECLAIMABLE_BYTES,
-                                   ksize(ext));
-       }
-
        this_cpu_inc(nr_dentry);
 
        return dentry;
@@ -2707,7 +2687,7 @@ static void copy_name(struct dentry *dentry, struct dentry *target)
                dentry->d_name.hash_len = target->d_name.hash_len;
        }
        if (old_name && likely(atomic_dec_and_test(&old_name->u.count)))
-               call_rcu(&old_name->u.head, __d_free_external_name);
+               kfree_rcu(old_name, u.head);
 }
 
 /*