ceph: preallocate buffer for readdir reply

Preallocate buffer for readdir reply. Limit number of entries in
readdir reply according to the buffer size.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

1 files changed, 51 insertions, 15 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 77640ada487a..19fbfc496137 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3,6 +3,7 @@
 #include <linux/fs.h>
 #include <linux/wait.h>
 #include <linux/slab.h>
+#include <linux/gfp.h>
 #include <linux/sched.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -165,21 +166,18 @@ static int parse_reply_info_dir(void **p, void *end,
         if (num == 0)
                 goto done;
 
-        /* alloc large array */
-        info->dir_nr = num;
-        info->dir_in = kcalloc(num, sizeof(*info->dir_in) +
-                               sizeof(*info->dir_dname) +
-                               sizeof(*info->dir_dname_len) +
-                               sizeof(*info->dir_dlease),
-                               GFP_NOFS);
-        if (info->dir_in == NULL) {
-                err = -ENOMEM;
-                goto out_bad;
-        }
+        BUG_ON(!info->dir_in);
         info->dir_dname = (void *)(info->dir_in + num);
         info->dir_dname_len = (void *)(info->dir_dname + num);
         info->dir_dlease = (void *)(info->dir_dname_len + num);
+        if ((unsigned long)(info->dir_dlease + num) >
+            (unsigned long)info->dir_in + info->dir_buf_size) {
+                pr_err("dir contents are larger than expected\n");
+                WARN_ON(1);
+                goto bad;
+        }
 
+        info->dir_nr = num;
         while (num) {
                 /* dentry */
                 ceph_decode_need(p, end, sizeof(u32)*2, bad);
@@ -327,7 +325,9 @@ out_bad:
 
 static void destroy_reply_info(struct ceph_mds_reply_info_parsed *info)
 {
-        kfree(info->dir_in);
+        if (!info->dir_in)
+                return;
+        free_pages((unsigned long)info->dir_in, get_order(info->dir_buf_size));
 }
 
 
@@ -512,12 +512,11 @@ void ceph_mdsc_release_request(struct kref *kref)
         struct ceph_mds_request *req = container_of(kref,
                                                     struct ceph_mds_request,
                                                     r_kref);
+        destroy_reply_info(&req->r_reply_info);
         if (req->r_request)
                 ceph_msg_put(req->r_request);
-        if (req->r_reply) {
+        if (req->r_reply)
                 ceph_msg_put(req->r_reply);
-                destroy_reply_info(&req->r_reply_info);
-        }
         if (req->r_inode) {
                 ceph_put_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
                 iput(req->r_inode);
@@ -1496,6 +1495,43 @@ static void discard_cap_releases(struct ceph_mds_client *mdsc,
  * requests
  */
 
+int ceph_alloc_readdir_reply_buffer(struct ceph_mds_request *req,
+                                    struct inode *dir)
+{
+        struct ceph_inode_info *ci = ceph_inode(dir);
+        struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
+        struct ceph_mount_options *opt = req->r_mdsc->fsc->mount_options;
+        size_t size = sizeof(*rinfo->dir_in) + sizeof(*rinfo->dir_dname_len) +
+                      sizeof(*rinfo->dir_dname) + sizeof(*rinfo->dir_dlease);
+        int order, num_entries;
+
+        spin_lock(&ci->i_ceph_lock);
+        num_entries = ci->i_files + ci->i_subdirs;
+        spin_unlock(&ci->i_ceph_lock);
+        num_entries = max(num_entries, 1);
+        num_entries = min(num_entries, opt->max_readdir);
+
+        order = get_order(size * num_entries);
+        while (order >= 0) {
+                rinfo->dir_in = (void*)__get_free_pages(GFP_NOFS | __GFP_NOWARN,
+                                                        order);
+                if (rinfo->dir_in)
+                        break;
+                order--;
+        }
+        if (!rinfo->dir_in)
+                return -ENOMEM;
+
+        num_entries = (PAGE_SIZE << order) / size;
+        num_entries = min(num_entries, opt->max_readdir);
+
+        rinfo->dir_buf_size = PAGE_SIZE << order;
+        req->r_num_caps = num_entries + 1;
+        req->r_args.readdir.max_entries = cpu_to_le32(num_entries);
+        req->r_args.readdir.max_bytes = cpu_to_le32(opt->max_readdir_bytes);
+        return 0;
+}
+
 /*
  * Create an mds request.
  */