ceph: optimize memory usage

In current code, regular file and directory use same struct
ceph_file_info to store fs specific data so the struct has to
include some fields which are only used for directory
(e.g., readdir related info), when having plenty of regular files,
it will lead to memory waste.

This patch introduces dedicated ceph_dir_file_info cache for
readdir related thins. So that regular file does not include those
unused fields anymore.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 62 insertions, 26 deletions

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index a1f0aee29c27..4a92acba1e9c 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -161,13 +161,50 @@ out:
         return req;
 }
 
+static int ceph_init_file_info(struct inode *inode, struct file *file,
+                                        int fmode, bool isdir)
+{
+        struct ceph_file_info *fi;
+
+        dout("%s %p %p 0%o (%s)\n", __func__, inode, file,
+                        inode->i_mode, isdir ? "dir" : "regular");
+        BUG_ON(inode->i_fop->release != ceph_release);
+
+        if (isdir) {
+                struct ceph_dir_file_info *dfi =
+                        kmem_cache_zalloc(ceph_dir_file_cachep, GFP_KERNEL);
+                if (!dfi) {
+                        ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+                        return -ENOMEM;
+                }
+
+                file->private_data = dfi;
+                fi = &dfi->file_info;
+                dfi->next_offset = 2;
+                dfi->readdir_cache_idx = -1;
+        } else {
+                fi = kmem_cache_zalloc(ceph_file_cachep, GFP_KERNEL);
+                if (!fi) {
+                        ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+                        return -ENOMEM;
+                }
+
+                file->private_data = fi;
+        }
+
+        fi->fmode = fmode;
+        spin_lock_init(&fi->rw_contexts_lock);
+        INIT_LIST_HEAD(&fi->rw_contexts);
+
+        return 0;
+}
+
 /*
  * initialize private struct file data.
  * if we fail, clean up by dropping fmode reference on the ceph_inode
  */
 static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
 {
-        struct ceph_file_info *fi;
         int ret = 0;
 
         switch (inode->i_mode & S_IFMT) {
@@ -175,22 +212,10 @@ static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
                 ceph_fscache_register_inode_cookie(inode);
                 ceph_fscache_file_set_cookie(inode, file);
         case S_IFDIR:
-                dout("init_file %p %p 0%o (regular)\n", inode, file,
-                     inode->i_mode);
-                fi = kmem_cache_zalloc(ceph_file_cachep, GFP_KERNEL);
-                if (!fi) {
-                        ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
-                        return -ENOMEM;
-                }
-                fi->fmode = fmode;
-
-                spin_lock_init(&fi->rw_contexts_lock);
-                INIT_LIST_HEAD(&fi->rw_contexts);
-
-                fi->next_offset = 2;
-                fi->readdir_cache_idx = -1;
-                file->private_data = fi;
-                BUG_ON(inode->i_fop->release != ceph_release);
+                ret = ceph_init_file_info(inode, file, fmode,
+                                                S_ISDIR(inode->i_mode));
+                if (ret)
+                        return ret;
                 break;
 
         case S_IFLNK:
@@ -462,16 +487,27 @@ out_acl:
 int ceph_release(struct inode *inode, struct file *file)
 {
         struct ceph_inode_info *ci = ceph_inode(inode);
-        struct ceph_file_info *fi = file->private_data;
 
-        dout("release inode %p file %p\n", inode, file);
-        ceph_put_fmode(ci, fi->fmode);
-        if (fi->last_readdir)
-                ceph_mdsc_put_request(fi->last_readdir);
-        kfree(fi->last_name);
-        kfree(fi->dir_info);
-        WARN_ON(!list_empty(&fi->rw_contexts));
-        kmem_cache_free(ceph_file_cachep, fi);
+        if (S_ISDIR(inode->i_mode)) {
+                struct ceph_dir_file_info *dfi = file->private_data;
+                dout("release inode %p dir file %p\n", inode, file);
+                WARN_ON(!list_empty(&dfi->file_info.rw_contexts));
+
+                ceph_put_fmode(ci, dfi->file_info.fmode);
+
+                if (dfi->last_readdir)
+                        ceph_mdsc_put_request(dfi->last_readdir);
+                kfree(dfi->last_name);
+                kfree(dfi->dir_info);
+                kmem_cache_free(ceph_dir_file_cachep, dfi);
+        } else {
+                struct ceph_file_info *fi = file->private_data;
+                dout("release inode %p regular file %p\n", inode, file);
+                WARN_ON(!list_empty(&fi->rw_contexts));
+
+                ceph_put_fmode(ci, fi->fmode);
+                kmem_cache_free(ceph_file_cachep, fi);
+        }
 
         /* wake up anyone waiting for caps on this inode */
         wake_up_all(&ci->i_cap_wq);