Revision 98bda63e20daab95bdc084ce00459a4f622a0505 authored by Roman Kiryanov on 19 February 2020, 21:40:06 UTC, committed by David S. Miller on 20 February 2020, 23:02:02 UTC
The description says 'If unsure, say N.' but the module is built as M by default (once the dependencies are satisfied). When the module is selected (Y or M), it enables NETFILTER_FAMILY_BRIDGE and SKB_EXTENSIONS which alter kernel internal structures. We (Android Studio Emulator) currently do not use this module and think this it is more consistent to have it disabled by default as opposite to disabling it explicitly to prevent enabling NETFILTER_FAMILY_BRIDGE and SKB_EXTENSIONS. Signed-off-by: Roman Kiryanov <rkir@google.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent ac2fcfa
namei.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2017-2018 HUAWEI, Inc.
* http://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*/
#include "xattr.h"
#include <trace/events/erofs.h>
struct erofs_qstr {
const unsigned char *name;
const unsigned char *end;
};
/* based on the end of qn is accurate and it must have the trailing '\0' */
static inline int erofs_dirnamecmp(const struct erofs_qstr *qn,
const struct erofs_qstr *qd,
unsigned int *matched)
{
unsigned int i = *matched;
/*
* on-disk error, let's only BUG_ON in the debugging mode.
* otherwise, it will return 1 to just skip the invalid name
* and go on (in consideration of the lookup performance).
*/
DBG_BUGON(qd->name > qd->end);
/* qd could not have trailing '\0' */
/* However it is absolutely safe if < qd->end */
while (qd->name + i < qd->end && qd->name[i] != '\0') {
if (qn->name[i] != qd->name[i]) {
*matched = i;
return qn->name[i] > qd->name[i] ? 1 : -1;
}
++i;
}
*matched = i;
/* See comments in __d_alloc on the terminating NUL character */
return qn->name[i] == '\0' ? 0 : 1;
}
#define nameoff_from_disk(off, sz) (le16_to_cpu(off) & ((sz) - 1))
static struct erofs_dirent *find_target_dirent(struct erofs_qstr *name,
u8 *data,
unsigned int dirblksize,
const int ndirents)
{
int head, back;
unsigned int startprfx, endprfx;
struct erofs_dirent *const de = (struct erofs_dirent *)data;
/* since the 1st dirent has been evaluated previously */
head = 1;
back = ndirents - 1;
startprfx = endprfx = 0;
while (head <= back) {
const int mid = head + (back - head) / 2;
const int nameoff = nameoff_from_disk(de[mid].nameoff,
dirblksize);
unsigned int matched = min(startprfx, endprfx);
struct erofs_qstr dname = {
.name = data + nameoff,
.end = mid >= ndirents - 1 ?
data + dirblksize :
data + nameoff_from_disk(de[mid + 1].nameoff,
dirblksize)
};
/* string comparison without already matched prefix */
int ret = erofs_dirnamecmp(name, &dname, &matched);
if (!ret) {
return de + mid;
} else if (ret > 0) {
head = mid + 1;
startprfx = matched;
} else {
back = mid - 1;
endprfx = matched;
}
}
return ERR_PTR(-ENOENT);
}
static struct page *find_target_block_classic(struct inode *dir,
struct erofs_qstr *name,
int *_ndirents)
{
unsigned int startprfx, endprfx;
int head, back;
struct address_space *const mapping = dir->i_mapping;
struct page *candidate = ERR_PTR(-ENOENT);
startprfx = endprfx = 0;
head = 0;
back = erofs_inode_datablocks(dir) - 1;
while (head <= back) {
const int mid = head + (back - head) / 2;
struct page *page = read_mapping_page(mapping, mid, NULL);
if (!IS_ERR(page)) {
struct erofs_dirent *de = kmap_atomic(page);
const int nameoff = nameoff_from_disk(de->nameoff,
EROFS_BLKSIZ);
const int ndirents = nameoff / sizeof(*de);
int diff;
unsigned int matched;
struct erofs_qstr dname;
if (!ndirents) {
kunmap_atomic(de);
put_page(page);
erofs_err(dir->i_sb,
"corrupted dir block %d @ nid %llu",
mid, EROFS_I(dir)->nid);
DBG_BUGON(1);
page = ERR_PTR(-EFSCORRUPTED);
goto out;
}
matched = min(startprfx, endprfx);
dname.name = (u8 *)de + nameoff;
if (ndirents == 1)
dname.end = (u8 *)de + EROFS_BLKSIZ;
else
dname.end = (u8 *)de +
nameoff_from_disk(de[1].nameoff,
EROFS_BLKSIZ);
/* string comparison without already matched prefix */
diff = erofs_dirnamecmp(name, &dname, &matched);
kunmap_atomic(de);
if (!diff) {
*_ndirents = 0;
goto out;
} else if (diff > 0) {
head = mid + 1;
startprfx = matched;
if (!IS_ERR(candidate))
put_page(candidate);
candidate = page;
*_ndirents = ndirents;
} else {
put_page(page);
back = mid - 1;
endprfx = matched;
}
continue;
}
out: /* free if the candidate is valid */
if (!IS_ERR(candidate))
put_page(candidate);
return page;
}
return candidate;
}
int erofs_namei(struct inode *dir,
struct qstr *name,
erofs_nid_t *nid, unsigned int *d_type)
{
int ndirents;
struct page *page;
void *data;
struct erofs_dirent *de;
struct erofs_qstr qn;
if (!dir->i_size)
return -ENOENT;
qn.name = name->name;
qn.end = name->name + name->len;
ndirents = 0;
page = find_target_block_classic(dir, &qn, &ndirents);
if (IS_ERR(page))
return PTR_ERR(page);
data = kmap_atomic(page);
/* the target page has been mapped */
if (ndirents)
de = find_target_dirent(&qn, data, EROFS_BLKSIZ, ndirents);
else
de = (struct erofs_dirent *)data;
if (!IS_ERR(de)) {
*nid = le64_to_cpu(de->nid);
*d_type = de->file_type;
}
kunmap_atomic(data);
put_page(page);
return PTR_ERR_OR_ZERO(de);
}
/* NOTE: i_mutex is already held by vfs */
static struct dentry *erofs_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags)
{
int err;
erofs_nid_t nid;
unsigned int d_type;
struct inode *inode;
DBG_BUGON(!d_really_is_negative(dentry));
/* dentry must be unhashed in lookup, no need to worry about */
DBG_BUGON(!d_unhashed(dentry));
trace_erofs_lookup(dir, dentry, flags);
/* file name exceeds fs limit */
if (dentry->d_name.len > EROFS_NAME_LEN)
return ERR_PTR(-ENAMETOOLONG);
/* false uninitialized warnings on gcc 4.8.x */
err = erofs_namei(dir, &dentry->d_name, &nid, &d_type);
if (err == -ENOENT) {
/* negative dentry */
inode = NULL;
} else if (err) {
inode = ERR_PTR(err);
} else {
erofs_dbg("%s, %s (nid %llu) found, d_type %u", __func__,
dentry->d_name.name, nid, d_type);
inode = erofs_iget(dir->i_sb, nid, d_type == FT_DIR);
}
return d_splice_alias(inode, dentry);
}
const struct inode_operations erofs_dir_iops = {
.lookup = erofs_lookup,
.getattr = erofs_getattr,
#ifdef CONFIG_EROFS_FS_XATTR
.listxattr = erofs_listxattr,
#endif
.get_acl = erofs_get_acl,
};
![swh spinner](/static/img/swh-spinner.gif)
Computing file changes ...