ovl: don't use a temp buf for encoding real fh

We can allocate maximum fh size and encode into it directly.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 7f744a9..6220642 100644 (file)
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -227,13 +227,17 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
 {
        struct ovl_fh *fh;
-       int fh_type, fh_len, dwords;
-       void *buf;
+       int fh_type, dwords;
        int buflen = MAX_HANDLE_SZ;
        uuid_t *uuid = &real->d_sb->s_uuid;
+       int err;
 
-       buf = kmalloc(buflen, GFP_KERNEL);
-       if (!buf)
+       /* Make sure the real fid stays 32bit aligned */
+       BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4);
+       BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255);
+
+       fh = kzalloc(buflen + OVL_FH_FID_OFFSET, GFP_KERNEL);
+       if (!fh)
                return ERR_PTR(-ENOMEM);
 
        /*
@@ -242,24 +246,14 @@ struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
         * the price or reconnecting the dentry.
         */
        dwords = buflen >> 2;
-       fh_type = exportfs_encode_fh(real, buf, &dwords, 0);
+       fh_type = exportfs_encode_fh(real, (void *)fh->fb.fid, &dwords, 0);
        buflen = (dwords << 2);
 
-       fh = ERR_PTR(-EIO);
+       err = -EIO;
        if (WARN_ON(fh_type < 0) ||
            WARN_ON(buflen > MAX_HANDLE_SZ) ||
            WARN_ON(fh_type == FILEID_INVALID))
-               goto out;
-
-       /* Make sure the real fid stays 32bit aligned */
-       BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4);
-       BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255);
-       fh_len = OVL_FH_FID_OFFSET + buflen;
-       fh = kzalloc(fh_len, GFP_KERNEL);
-       if (!fh) {
-               fh = ERR_PTR(-ENOMEM);
-               goto out;
-       }
+               goto out_err;
 
        fh->fb.version = OVL_FH_VERSION;
        fh->fb.magic = OVL_FH_MAGIC;
@@ -273,13 +267,14 @@ struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
         */
        if (is_upper)
                fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER;
-       fh->fb.len = fh_len - OVL_FH_WIRE_OFFSET;
+       fh->fb.len = sizeof(fh->fb) + buflen;
        fh->fb.uuid = *uuid;
-       memcpy(fh->fb.fid, buf, buflen);
 
-out:
-       kfree(buf);
        return fh;
+
+out_err:
+       kfree(fh);
+       return ERR_PTR(err);
 }
 
 int ovl_set_origin(struct dentry *dentry, struct dentry *lower,