This adds functions for directory, mainly readdir. Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx> --- fs/erofs/dir.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 147 insertions(+) create mode 100644 fs/erofs/dir.c diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c new file mode 100644 index 000000000000..7cf7da8574c4 --- /dev/null +++ b/fs/erofs/dir.c @@ -0,0 +1,147 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/fs/erofs/dir.c + * + * Copyright (C) 2017-2018 HUAWEI, Inc. + * http://www.huawei.com/ + * Created by Gao Xiang <gaoxiang25@xxxxxxxxxx> + */ +#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 void debug_one_dentry(unsigned char d_type, const char *de_name, + unsigned int de_namelen) +{ +#ifdef CONFIG_EROFS_FS_DEBUG + /* since the on-disk name could not have the trailing '\0' */ + unsigned char dbg_namebuf[EROFS_NAME_LEN + 1]; + + memcpy(dbg_namebuf, de_name, de_namelen); + dbg_namebuf[de_namelen] = '\0'; + + debugln("found dirent %s de_len %u d_type %d", dbg_namebuf, + de_namelen, d_type); +#endif +} + +static int erofs_fill_dentries(struct dir_context *ctx, + void *dentry_blk, unsigned int *ofs, + unsigned int nameoff, unsigned int maxsize) +{ + struct erofs_dirent *de = dentry_blk + *ofs; + const struct erofs_dirent *end = dentry_blk + nameoff; + + while (de < end) { + const char *de_name; + unsigned int de_namelen; + unsigned char d_type; + + if (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; + + /* the last dirent in the block? */ + if (de + 1 >= end) + de_namelen = strnlen(de_name, maxsize - nameoff); + else + de_namelen = le16_to_cpu(de[1].nameoff) - nameoff; + + /* a corrupted entry is found */ + if (unlikely(nameoff + de_namelen > maxsize || + de_namelen > EROFS_NAME_LEN)) { + DBG_BUGON(1); + return -EIO; + } + + debug_one_dentry(d_type, de_name, de_namelen); + if (!dir_emit(ctx, de_name, de_namelen, + le64_to_cpu(de->nid), d_type)) + /* stopped 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 int i = ctx->pos / EROFS_BLKSIZ; + unsigned int ofs = ctx->pos % EROFS_BLKSIZ; + int err = 0; + bool initial = true; + + while (ctx->pos < dirsize) { + struct page *dentry_page; + struct erofs_dirent *de; + unsigned int nameoff, maxsize; + + dentry_page = read_mapping_page(mapping, i, NULL); + if (IS_ERR(dentry_page)) + continue; + + 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 int, + 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); + + 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_shared = erofs_readdir, +}; + -- 2.17.1
