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Subject[PATCH 06/25] staging: erofs: add directory operations
Date
This adds functions for directory, mainly readdir.

Signed-off-by: Miao Xie <miaoxie@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
drivers/staging/erofs/dir.c | 145 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 145 insertions(+)
create mode 100644 drivers/staging/erofs/dir.c

diff --git a/drivers/staging/erofs/dir.c b/drivers/staging/erofs/dir.c
new file mode 100644
index 0000000..be6ae3b
--- /dev/null
+++ b/drivers/staging/erofs/dir.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/drivers/staging/erofs/dir.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"
+
+static const unsigned char erofs_filetype_table[EROFS_FT_MAX] = {
+ [EROFS_FT_UNKNOWN] = DT_UNKNOWN,
+ [EROFS_FT_REG_FILE] = DT_REG,
+ [EROFS_FT_DIR] = DT_DIR,
+ [EROFS_FT_CHRDEV] = DT_CHR,
+ [EROFS_FT_BLKDEV] = DT_BLK,
+ [EROFS_FT_FIFO] = DT_FIFO,
+ [EROFS_FT_SOCK] = DT_SOCK,
+ [EROFS_FT_SYMLINK] = DT_LNK,
+};
+
+static int erofs_fill_dentries(struct dir_context *ctx,
+ void *dentry_blk, unsigned *ofs,
+ unsigned nameoff, unsigned maxsize)
+{
+ struct erofs_dirent *de = dentry_blk;
+ const struct erofs_dirent *end = dentry_blk + nameoff;
+
+ de = dentry_blk + *ofs;
+ while (de < end) {
+ const char *de_name;
+ int de_namelen;
+ unsigned char d_type;
+#ifdef CONFIG_EROFS_FS_DEBUG
+ unsigned dbg_namelen;
+ unsigned char dbg_namebuf[EROFS_NAME_LEN];
+#endif
+
+ if (unlikely(de->file_type < EROFS_FT_MAX))
+ d_type = erofs_filetype_table[de->file_type];
+ else
+ d_type = DT_UNKNOWN;
+
+ nameoff = le16_to_cpu(de->nameoff);
+ de_name = (char *)dentry_blk + nameoff;
+
+ de_namelen = unlikely(de + 1 >= end) ?
+ /* last directory entry */
+ strnlen(de_name, maxsize - nameoff) :
+ le16_to_cpu(de[1].nameoff) - nameoff;
+
+ /* the corrupted directory found */
+ BUG_ON(de_namelen < 0);
+
+#ifdef CONFIG_EROFS_FS_DEBUG
+ dbg_namelen = min(EROFS_NAME_LEN - 1, de_namelen);
+ memcpy(dbg_namebuf, de_name, dbg_namelen);
+ dbg_namebuf[dbg_namelen] = '\0';
+
+ debugln("%s, found de_name %s de_len %d d_type %d", __func__,
+ dbg_namebuf, de_namelen, d_type);
+#endif
+
+ if (!dir_emit(ctx, de_name, de_namelen,
+ le64_to_cpu(de->nid), d_type))
+ /* stoped by some reason */
+ return 1;
+ ++de;
+ *ofs += sizeof(struct erofs_dirent);
+ }
+ *ofs = maxsize;
+ return 0;
+}
+
+static int erofs_readdir(struct file *f, struct dir_context *ctx)
+{
+ struct inode *dir = file_inode(f);
+ struct address_space *mapping = dir->i_mapping;
+ const size_t dirsize = i_size_read(dir);
+ unsigned i = ctx->pos / EROFS_BLKSIZ;
+ unsigned ofs = ctx->pos % EROFS_BLKSIZ;
+ int err = 0;
+ bool initial = true;
+
+ while (ctx->pos < dirsize) {
+ struct page *dentry_page;
+ struct erofs_dirent *de;
+ unsigned nameoff, maxsize;
+
+ dentry_page = read_mapping_page(mapping, i, NULL);
+ if (IS_ERR(dentry_page))
+ continue;
+
+ lock_page(dentry_page);
+ de = (struct erofs_dirent *)kmap(dentry_page);
+
+ nameoff = le16_to_cpu(de->nameoff);
+
+ if (unlikely(nameoff < sizeof(struct erofs_dirent) ||
+ nameoff >= PAGE_SIZE)) {
+ errln("%s, invalid de[0].nameoff %u",
+ __func__, nameoff);
+
+ err = -EIO;
+ goto skip_this;
+ }
+
+ maxsize = min_t(unsigned, dirsize - ctx->pos + ofs, PAGE_SIZE);
+
+ /* search dirents at the arbitrary position */
+ if (unlikely(initial)) {
+ initial = false;
+
+ ofs = roundup(ofs, sizeof(struct erofs_dirent));
+ if (unlikely(ofs >= nameoff))
+ goto skip_this;
+ }
+
+ err = erofs_fill_dentries(ctx, de, &ofs, nameoff, maxsize);
+skip_this:
+ kunmap(dentry_page);
+
+ unlock_page(dentry_page);
+ put_page(dentry_page);
+
+ ctx->pos = blknr_to_addr(i) + ofs;
+
+ if (unlikely(err))
+ break;
+ ++i;
+ ofs = 0;
+ }
+ return err < 0 ? err : 0;
+}
+
+const struct file_operations erofs_dir_fops = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .iterate = erofs_readdir,
+};
+
--
1.9.1
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