kclient: preallocated buffer for the xattr blob

diff --git a/src/kernel/inode.c b/src/kernel/inode.c
index 81bcd46d7fbdd5b731392e04673839c056aef42b..97dcf21551bd665b99e21cd8b1fcb3d51a6129dc 100644 (file)
--- a/src/kernel/inode.c
+++ b/src/kernel/inode.c
@@ -266,6 +266,7 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
        ci->i_xattrs.xattrs = RB_ROOT;
        ci->i_xattrs.len = 0;
        ci->i_xattrs.data = NULL;
+       ci->i_xattrs.count = 0;
        ci->i_xattrs.names_size = 0;
        ci->i_xattrs.prealloc_blob = 0;
        ci->i_xattrs.prealloc_size = 0;
@@ -1664,6 +1665,8 @@ static int __set_xattr(struct ceph_inode_info *ci,
                xattr->name = name;
                xattr->name_len = name_len;
                xattr->should_free_name = should_free_name;
+
+               ci->i_xattrs.count++;
        } else {
                kfree(*newxattr);
                *newxattr = NULL;
@@ -1756,6 +1759,7 @@ static void __remove_xattr(struct ceph_inode_info *ci,
 
        ci->i_xattrs.names_size -= (xattr->name_len + 1);
        ci->i_xattrs.vals_size -= (xattr->val_len + 1);
+       ci->i_xattrs.count--;
        kfree(xattr);
 }
 
@@ -1822,7 +1826,7 @@ static int __build_xattrs(struct inode *inode)
        const char *name, *val;
        struct ceph_inode_info *ci = ceph_inode(inode);
        int xattr_version;
-       struct ceph_inode_xattr **xattrs;
+       struct ceph_inode_xattr **xattrs = NULL;
        int err;
        int i;
 
@@ -1890,6 +1894,40 @@ bad:
        return err;
 }
 
+void *__ceph_build_xattrs_blob(struct ceph_inode_info *ci)
+{
+       struct rb_node *p;
+       struct ceph_inode_xattr *xattr = NULL;
+       void *dest;
+
+       if (ci->i_xattrs.names_size) {
+               BUG_ON(!ci->i_xattrs.prealloc_blob);
+
+               p = rb_first(&ci->i_xattrs.xattrs);
+
+               dest = ci->i_xattrs.prealloc_blob;
+               ceph_encode_32(&dest, ci->i_xattrs.count);
+
+               while (p) {
+                       xattr = rb_entry(p, struct ceph_inode_xattr, node);
+
+                       ceph_encode_32(&dest, xattr->name_len);
+                       memcpy(dest, xattr->name, xattr->name_len);
+                       dest += xattr->name_len;
+                       ceph_encode_32(&dest, xattr->val_len);
+                       memcpy(dest, xattr->val, xattr->val_len);
+                       dest += xattr->val_len;
+
+                       p = rb_next(p);
+               }
+       
+               return ci->i_xattrs.prealloc_blob;
+       } else {
+               /*just use the blob that we hold */
+               return ci->i_xattrs.data;
+       }
+}
+
 ssize_t ceph_getxattr(struct dentry *dentry, const char *name, void *value,
                      size_t size)
 {
@@ -2045,6 +2083,13 @@ out:
        return err;
 }
 
+int __get_required_blob_size(struct ceph_inode_info *ci)
+{
+       return  4 + ci->i_xattrs.count*(4 + 4) +
+                            ci->i_xattrs.names_size +
+                            ci->i_xattrs.vals_size;
+}
+
 int ceph_setxattr(struct dentry *dentry, const char *name,
                  const void *value, size_t size, int flags)
 {
@@ -2058,6 +2103,9 @@ int ceph_setxattr(struct dentry *dentry, const char *name,
        int issued;
        int dirtied = 0;
        struct ceph_inode_xattr *xattr;
+       int required_blob_size, cur_blob_size;
+       int need_alloc = 0;
+       void *prealloc_blob = NULL;
 
        if (ceph_snap(inode) != CEPH_NOSNAP)
                return -EROFS;
@@ -2089,8 +2137,41 @@ int ceph_setxattr(struct dentry *dentry, const char *name,
        if (!xattr)
                goto out;
 
+       spin_lock(&inode->i_lock);
+       required_blob_size = __get_required_blob_size(ci);
+alloc_buf:
+
+       if (required_blob_size > ci->i_xattrs.prealloc_size)
+               need_alloc = 1;
+
+       spin_unlock(&inode->i_lock);
+
+       if (need_alloc) {
+               prealloc_blob = kmalloc(required_blob_size, GFP_NOFS);
+
+               if (!prealloc_blob)
+                       goto out;
+       }
+
        dout(0, "setxattr newname=%s\n", newname);
        spin_lock(&inode->i_lock);
+       cur_blob_size = __get_required_blob_size(ci);
+
+       if (need_alloc &&
+           required_blob_size < cur_blob_size) {
+               /* lost a race, preallocated buffer is too small */
+               kfree(prealloc_blob);
+               required_blob_size = cur_blob_size;
+               goto alloc_buf;
+       }
+
+       if (need_alloc) {
+               void *old_buf = ci->i_xattrs.prealloc_blob;
+               ci->i_xattrs.prealloc_blob = prealloc_blob;
+               if (old_buf)
+                       kfree(old_buf);
+       }
+
        issued = __ceph_caps_issued(ci, NULL);
        dout(10, "setxattr %p issued %s\n", inode, ceph_cap_string(issued));
 

diff --git a/src/kernel/super.h b/src/kernel/super.h
index c8343174ac697ce9ac77f0a4a0bd34cc2c241321..d93f4ccce951eea1a982e1a3251500e9c0032f6a 100644 (file)
--- a/src/kernel/super.h
+++ b/src/kernel/super.h
@@ -252,6 +252,7 @@ struct ceph_inode_xattrs_info {
        */
        int len;
        char *data;
+       int count;
        int names_size;
        int vals_size;
        u64 version;