staging: erofs: add inode operations

This adds core functions to get, read an inode.

Signed-off-by: Miao Xie <miaoxie@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
new file mode 100644 (file)
index 0000000..74e65be
--- /dev/null
+++ b/drivers/staging/erofs/inode.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/drivers/staging/erofs/inode.c
+ *
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ *             http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+#include "internal.h"
+
+/* no locking */
+static int read_inode(struct inode *inode, void *data)
+{
+       struct erofs_vnode *vi = EROFS_V(inode);
+       struct erofs_inode_v1 *v1 = data;
+       const unsigned advise = le16_to_cpu(v1->i_advise);
+
+       vi->data_mapping_mode = __inode_data_mapping(advise);
+
+       if (unlikely(vi->data_mapping_mode >= EROFS_INODE_LAYOUT_MAX)) {
+               errln("unknown data mapping mode %u of nid %llu",
+                       vi->data_mapping_mode, vi->nid);
+               DBG_BUGON(1);
+               return -EIO;
+       }
+
+       if (__inode_version(advise) == EROFS_INODE_LAYOUT_V2) {
+               struct erofs_inode_v2 *v2 = data;
+
+               vi->inode_isize = sizeof(struct erofs_inode_v2);
+               vi->xattr_isize = ondisk_xattr_ibody_size(v2->i_xattr_icount);
+
+               vi->raw_blkaddr = le32_to_cpu(v2->i_u.raw_blkaddr);
+               inode->i_mode = le16_to_cpu(v2->i_mode);
+
+               i_uid_write(inode, le32_to_cpu(v2->i_uid));
+               i_gid_write(inode, le32_to_cpu(v2->i_gid));
+               set_nlink(inode, le32_to_cpu(v2->i_nlink));
+
+               /* ns timestamp */
+               inode->i_mtime.tv_sec = inode->i_ctime.tv_sec =
+                       le64_to_cpu(v2->i_ctime);
+               inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec =
+                       le32_to_cpu(v2->i_ctime_nsec);
+
+               inode->i_size = le64_to_cpu(v2->i_size);
+       } else if (__inode_version(advise) == EROFS_INODE_LAYOUT_V1) {
+               struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
+
+               vi->inode_isize = sizeof(struct erofs_inode_v1);
+               vi->xattr_isize = ondisk_xattr_ibody_size(v1->i_xattr_icount);
+
+               vi->raw_blkaddr = le32_to_cpu(v1->i_u.raw_blkaddr);
+               inode->i_mode = le16_to_cpu(v1->i_mode);
+
+               i_uid_write(inode, le16_to_cpu(v1->i_uid));
+               i_gid_write(inode, le16_to_cpu(v1->i_gid));
+               set_nlink(inode, le16_to_cpu(v1->i_nlink));
+
+               /* use build time to derive all file time */
+               inode->i_mtime.tv_sec = inode->i_ctime.tv_sec =
+                       sbi->build_time;
+               inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec =
+                       sbi->build_time_nsec;
+
+               inode->i_size = le32_to_cpu(v1->i_size);
+       } else {
+               errln("unsupported on-disk inode version %u of nid %llu",
+                       __inode_version(advise), vi->nid);
+               DBG_BUGON(1);
+               return -EIO;
+       }
+
+       /* measure inode.i_blocks as the generic filesystem */
+       inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;
+       return 0;
+}
+
+/*
+ * try_lock can be required since locking order is:
+ *   file data(fs_inode)
+ *        meta(bd_inode)
+ * but the majority of the callers is "iget",
+ * in that case we are pretty sure no deadlock since
+ * no data operations exist. However I tend to
+ * try_lock since it takes no much overhead and
+ * will success immediately.
+ */
+static int fill_inline_data(struct inode *inode, void *data, unsigned m_pofs)
+{
+       struct erofs_vnode *vi = EROFS_V(inode);
+       int mode = vi->data_mapping_mode;
+
+       DBG_BUGON(mode >= EROFS_INODE_LAYOUT_MAX);
+
+       /* should be inode inline C */
+       if (mode != EROFS_INODE_LAYOUT_INLINE)
+               return 0;
+
+       /* fast symlink (following ext4) */
+       if (S_ISLNK(inode->i_mode) && inode->i_size < PAGE_SIZE) {
+               char *lnk = kmalloc(inode->i_size + 1, GFP_KERNEL);
+
+               if (unlikely(lnk == NULL))
+                       return -ENOMEM;
+
+               m_pofs += vi->inode_isize + vi->xattr_isize;
+               BUG_ON(m_pofs + inode->i_size > PAGE_SIZE);
+
+               /* get in-page inline data */
+               memcpy(lnk, data + m_pofs, inode->i_size);
+               lnk[inode->i_size] = '\0';
+
+               inode->i_link = lnk;
+               set_inode_fast_symlink(inode);
+       }
+       return -EAGAIN;
+}
+
+static int fill_inode(struct inode *inode, int isdir)
+{
+       struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
+       struct erofs_vnode *vi = EROFS_V(inode);
+       struct page *page;
+       void *data;
+       int err;
+       erofs_blk_t blkaddr;
+       unsigned ofs;
+
+       blkaddr = erofs_blknr(iloc(sbi, vi->nid));
+       ofs = erofs_blkoff(iloc(sbi, vi->nid));
+
+       debugln("%s, reading inode nid %llu at %u of blkaddr %u",
+               __func__, vi->nid, ofs, blkaddr);
+
+       page = erofs_get_meta_page(inode->i_sb, blkaddr, isdir);
+
+       if (IS_ERR(page)) {
+               errln("failed to get inode (nid: %llu) page, err %ld",
+                       vi->nid, PTR_ERR(page));
+               return PTR_ERR(page);
+       }
+
+       BUG_ON(!PageUptodate(page));
+       data = page_address(page);
+
+       err = read_inode(inode, data + ofs);
+       if (!err) {
+               /* setup the new inode */
+               if (S_ISREG(inode->i_mode)) {
+                       inode->i_fop = &generic_ro_fops;
+               } else if (S_ISDIR(inode->i_mode)) {
+                       inode->i_op =
+                               &erofs_dir_iops;
+                       inode->i_fop = &erofs_dir_fops;
+               } else if (S_ISLNK(inode->i_mode)) {
+                       /* by default, page_get_link is used for symlink */
+                       inode->i_op =
+                               &page_symlink_inode_operations;
+                       inode_nohighmem(inode);
+               } else {
+                       err = -EIO;
+                       goto out_unlock;
+               }
+
+               if (is_inode_layout_compression(inode)) {
+                       err = -ENOTSUPP;
+                       goto out_unlock;
+               }
+
+               inode->i_mapping->a_ops = &erofs_raw_access_aops;
+
+               /* fill last page if inline data is available */
+               fill_inline_data(inode, data, ofs);
+       }
+
+out_unlock:
+       unlock_page(page);
+       put_page(page);
+       return err;
+}
+
+struct inode *erofs_iget(struct super_block *sb,
+       erofs_nid_t nid, bool isdir)
+{
+       struct inode *inode = iget_locked(sb, nid);
+
+       if (unlikely(inode == NULL))
+               return ERR_PTR(-ENOMEM);
+
+       if (inode->i_state & I_NEW) {
+               int err;
+               struct erofs_vnode *vi = EROFS_V(inode);
+               vi->nid = nid;
+
+               err = fill_inode(inode, isdir);
+               if (likely(!err))
+                       unlock_new_inode(inode);
+               else {
+                       iget_failed(inode);
+                       inode = ERR_PTR(err);
+               }
+       }
+       return inode;
+}
+