[RFC PATCH 05/25] staging: erofs: add inode operations
Gao Xiang
gaoxiang25 at huawei.com
Tue Jul 24 12:36:25 AEST 2018
This adds core functions to get, read an inode.
Signed-off-by: Miao Xie <miaoxie at huawei.com>
Signed-off-by: Chao Yu <yuchao0 at huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
drivers/staging/erofs/inode.c | 231 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 231 insertions(+)
create mode 100644 drivers/staging/erofs/inode.c
diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c
new file mode 100644
index 0000000..b9a9d2c
--- /dev/null
+++ b/drivers/staging/erofs/inode.c
@@ -0,0 +1,231 @@
+// 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 at 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.
+ */
+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';
+
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0))
+ vi->i_link = lnk;
+#else
+ inode->i_link = lnk;
+#endif
+ set_inode_fast_symlink(inode);
+ }
+ return -EAGAIN;
+}
+
+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;
+}
+
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0))
+#include <linux/namei.h>
+
+static void *erofs_follow_fast_link(struct dentry *dentry, struct nameidata *nd)
+{
+ struct erofs_vnode *vi = EROFS_V(d_inode(dentry));
+
+ nd_set_link(nd, (char *)vi->i_link);
+ return NULL;
+}
+
+const struct inode_operations simple_symlink_inode_operations = {
+ .follow_link = erofs_follow_fast_link,
+ .readlink = generic_readlink
+};
+#endif
+
--
1.9.1
More information about the Linux-erofs
mailing list