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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2017-2018 HUAWEI, Inc.
* https://www.huawei.com/
* Copyright (C) 2022, Alibaba Cloud
*/
#include "internal.h"
static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
void *dentry_blk, struct erofs_dirent *de,
unsigned int nameoff0, unsigned int maxsize)
{
const struct erofs_dirent *end = dentry_blk + nameoff0;
while (de < end) {
unsigned char d_type = fs_ftype_to_dtype(de->file_type);
unsigned int nameoff = le16_to_cpu(de->nameoff);
const char *de_name = (char *)dentry_blk + nameoff;
unsigned int de_namelen;
/* 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 (nameoff + de_namelen > maxsize ||
de_namelen > EROFS_NAME_LEN) {
erofs_err(dir->i_sb, "bogus dirent @ nid %llu",
EROFS_I(dir)->nid);
DBG_BUGON(1);
return -EFSCORRUPTED;
}
if (!dir_emit(ctx, de_name, de_namelen,
erofs_nid_to_ino64(EROFS_SB(dir->i_sb),
le64_to_cpu(de->nid)), d_type))
return 1;
++de;
ctx->pos += sizeof(struct erofs_dirent);
}
return 0;
}
static int erofs_readdir(struct file *f, struct dir_context *ctx)
{
struct inode *dir = file_inode(f);
struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
struct super_block *sb = dir->i_sb;
struct file_ra_state *ra = &f->f_ra;
unsigned long bsz = sb->s_blocksize;
unsigned int ofs = erofs_blkoff(sb, ctx->pos);
pgoff_t ra_pages = DIV_ROUND_UP_POW2(
EROFS_I_SB(dir)->dir_ra_bytes, PAGE_SIZE);
pgoff_t nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
int err = 0;
bool initial = true;
buf.mapping = dir->i_mapping;
while (ctx->pos < dir->i_size) {
erofs_off_t dbstart = ctx->pos - ofs;
struct erofs_dirent *de;
unsigned int nameoff, maxsize;
if (fatal_signal_pending(current)) {
err = -ERESTARTSYS;
break;
}
/* readahead blocks to enhance performance for large directories */
if (ra_pages) {
pgoff_t idx = DIV_ROUND_UP_POW2(ctx->pos, PAGE_SIZE);
pgoff_t pages = min(nr_pages - idx, ra_pages);
if (pages > 1 && !ra_has_index(ra, idx))
page_cache_sync_readahead(dir->i_mapping, ra,
f, idx, pages);
}
de = erofs_bread(&buf, dbstart, true);
if (IS_ERR(de)) {
erofs_err(sb, "failed to readdir of logical block %llu of nid %llu",
erofs_blknr(sb, dbstart), EROFS_I(dir)->nid);
err = PTR_ERR(de);
break;
}
nameoff = le16_to_cpu(de->nameoff);
if (nameoff < sizeof(struct erofs_dirent) || nameoff >= bsz) {
erofs_err(sb, "invalid de[0].nameoff %u @ nid %llu",
nameoff, EROFS_I(dir)->nid);
err = -EFSCORRUPTED;
break;
}
maxsize = min_t(unsigned int, dir->i_size - dbstart, bsz);
/* search dirents at the arbitrary position */
if (initial) {
initial = false;
ofs = roundup(ofs, sizeof(struct erofs_dirent));
ctx->pos = dbstart + ofs;
}
err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
nameoff, maxsize);
if (err)
break;
ctx->pos = dbstart + maxsize;
ofs = 0;
cond_resched();
}
erofs_put_metabuf(&buf);
if (EROFS_I(dir)->dot_omitted && ctx->pos == dir->i_size) {
if (!dir_emit_dot(f, ctx))
return 0;
++ctx->pos;
}
return err < 0 ? err : 0;
}
const struct file_operations erofs_dir_fops = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = erofs_readdir,
.unlocked_ioctl = erofs_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = erofs_compat_ioctl,
#endif
};
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