/usr/src/aufs-4.9+20161219/fs/aufs/export.c is in aufs-dkms 4.9+20161219-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* Copyright (C) 2005-2016 Junjiro R. Okajima
*
* This program, aufs is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* export via nfs
*/
#include <linux/exportfs.h>
#include <linux/fs_struct.h>
#include <linux/namei.h>
#include <linux/nsproxy.h>
#include <linux/random.h>
#include <linux/writeback.h>
#include "aufs.h"
union conv {
#ifdef CONFIG_AUFS_INO_T_64
__u32 a[2];
#else
__u32 a[1];
#endif
ino_t ino;
};
static ino_t decode_ino(__u32 *a)
{
union conv u;
BUILD_BUG_ON(sizeof(u.ino) != sizeof(u.a));
u.a[0] = a[0];
#ifdef CONFIG_AUFS_INO_T_64
u.a[1] = a[1];
#endif
return u.ino;
}
static void encode_ino(__u32 *a, ino_t ino)
{
union conv u;
u.ino = ino;
a[0] = u.a[0];
#ifdef CONFIG_AUFS_INO_T_64
a[1] = u.a[1];
#endif
}
/* NFS file handle */
enum {
Fh_br_id,
Fh_sigen,
#ifdef CONFIG_AUFS_INO_T_64
/* support 64bit inode number */
Fh_ino1,
Fh_ino2,
Fh_dir_ino1,
Fh_dir_ino2,
#else
Fh_ino1,
Fh_dir_ino1,
#endif
Fh_igen,
Fh_h_type,
Fh_tail,
Fh_ino = Fh_ino1,
Fh_dir_ino = Fh_dir_ino1
};
static int au_test_anon(struct dentry *dentry)
{
/* note: read d_flags without d_lock */
return !!(dentry->d_flags & DCACHE_DISCONNECTED);
}
int au_test_nfsd(void)
{
int ret;
struct task_struct *tsk = current;
char comm[sizeof(tsk->comm)];
ret = 0;
if (tsk->flags & PF_KTHREAD) {
get_task_comm(comm, tsk);
ret = !strcmp(comm, "nfsd");
}
return ret;
}
/* ---------------------------------------------------------------------- */
/* inode generation external table */
void au_xigen_inc(struct inode *inode)
{
loff_t pos;
ssize_t sz;
__u32 igen;
struct super_block *sb;
struct au_sbinfo *sbinfo;
sb = inode->i_sb;
AuDebugOn(!au_opt_test(au_mntflags(sb), XINO));
sbinfo = au_sbi(sb);
pos = inode->i_ino;
pos *= sizeof(igen);
igen = inode->i_generation + 1;
sz = xino_fwrite(sbinfo->si_xwrite, sbinfo->si_xigen, &igen,
sizeof(igen), &pos);
if (sz == sizeof(igen))
return; /* success */
if (unlikely(sz >= 0))
AuIOErr("xigen error (%zd)\n", sz);
}
int au_xigen_new(struct inode *inode)
{
int err;
loff_t pos;
ssize_t sz;
struct super_block *sb;
struct au_sbinfo *sbinfo;
struct file *file;
err = 0;
/* todo: dirty, at mount time */
if (inode->i_ino == AUFS_ROOT_INO)
goto out;
sb = inode->i_sb;
SiMustAnyLock(sb);
if (unlikely(!au_opt_test(au_mntflags(sb), XINO)))
goto out;
err = -EFBIG;
pos = inode->i_ino;
if (unlikely(au_loff_max / sizeof(inode->i_generation) - 1 < pos)) {
AuIOErr1("too large i%lld\n", pos);
goto out;
}
pos *= sizeof(inode->i_generation);
err = 0;
sbinfo = au_sbi(sb);
file = sbinfo->si_xigen;
BUG_ON(!file);
if (vfsub_f_size_read(file)
< pos + sizeof(inode->i_generation)) {
inode->i_generation = atomic_inc_return(&sbinfo->si_xigen_next);
sz = xino_fwrite(sbinfo->si_xwrite, file, &inode->i_generation,
sizeof(inode->i_generation), &pos);
} else
sz = xino_fread(sbinfo->si_xread, file, &inode->i_generation,
sizeof(inode->i_generation), &pos);
if (sz == sizeof(inode->i_generation))
goto out; /* success */
err = sz;
if (unlikely(sz >= 0)) {
err = -EIO;
AuIOErr("xigen error (%zd)\n", sz);
}
out:
return err;
}
int au_xigen_set(struct super_block *sb, struct file *base)
{
int err;
struct au_sbinfo *sbinfo;
struct file *file;
SiMustWriteLock(sb);
sbinfo = au_sbi(sb);
file = au_xino_create2(base, sbinfo->si_xigen);
err = PTR_ERR(file);
if (IS_ERR(file))
goto out;
err = 0;
if (sbinfo->si_xigen)
fput(sbinfo->si_xigen);
sbinfo->si_xigen = file;
out:
return err;
}
void au_xigen_clr(struct super_block *sb)
{
struct au_sbinfo *sbinfo;
SiMustWriteLock(sb);
sbinfo = au_sbi(sb);
if (sbinfo->si_xigen) {
fput(sbinfo->si_xigen);
sbinfo->si_xigen = NULL;
}
}
/* ---------------------------------------------------------------------- */
static struct dentry *decode_by_ino(struct super_block *sb, ino_t ino,
ino_t dir_ino)
{
struct dentry *dentry, *d;
struct inode *inode;
unsigned int sigen;
dentry = NULL;
inode = ilookup(sb, ino);
if (!inode)
goto out;
dentry = ERR_PTR(-ESTALE);
sigen = au_sigen(sb);
if (unlikely(au_is_bad_inode(inode)
|| IS_DEADDIR(inode)
|| sigen != au_iigen(inode, NULL)))
goto out_iput;
dentry = NULL;
if (!dir_ino || S_ISDIR(inode->i_mode))
dentry = d_find_alias(inode);
else {
spin_lock(&inode->i_lock);
hlist_for_each_entry(d, &inode->i_dentry, d_u.d_alias) {
spin_lock(&d->d_lock);
if (!au_test_anon(d)
&& d_inode(d->d_parent)->i_ino == dir_ino) {
dentry = dget_dlock(d);
spin_unlock(&d->d_lock);
break;
}
spin_unlock(&d->d_lock);
}
spin_unlock(&inode->i_lock);
}
if (unlikely(dentry && au_digen_test(dentry, sigen))) {
/* need to refresh */
dput(dentry);
dentry = NULL;
}
out_iput:
iput(inode);
out:
AuTraceErrPtr(dentry);
return dentry;
}
/* ---------------------------------------------------------------------- */
/* todo: dirty? */
/* if exportfs_decode_fh() passed vfsmount*, we could be happy */
struct au_compare_mnt_args {
/* input */
struct super_block *sb;
/* output */
struct vfsmount *mnt;
};
static int au_compare_mnt(struct vfsmount *mnt, void *arg)
{
struct au_compare_mnt_args *a = arg;
if (mnt->mnt_sb != a->sb)
return 0;
a->mnt = mntget(mnt);
return 1;
}
static struct vfsmount *au_mnt_get(struct super_block *sb)
{
int err;
struct path root;
struct au_compare_mnt_args args = {
.sb = sb
};
get_fs_root(current->fs, &root);
rcu_read_lock();
err = iterate_mounts(au_compare_mnt, &args, root.mnt);
rcu_read_unlock();
path_put(&root);
AuDebugOn(!err);
AuDebugOn(!args.mnt);
return args.mnt;
}
struct au_nfsd_si_lock {
unsigned int sigen;
aufs_bindex_t bindex, br_id;
unsigned char force_lock;
};
static int si_nfsd_read_lock(struct super_block *sb,
struct au_nfsd_si_lock *nsi_lock)
{
int err;
aufs_bindex_t bindex;
si_read_lock(sb, AuLock_FLUSH);
/* branch id may be wrapped around */
err = 0;
bindex = au_br_index(sb, nsi_lock->br_id);
if (bindex >= 0 && nsi_lock->sigen + AUFS_BRANCH_MAX > au_sigen(sb))
goto out; /* success */
err = -ESTALE;
bindex = -1;
if (!nsi_lock->force_lock)
si_read_unlock(sb);
out:
nsi_lock->bindex = bindex;
return err;
}
struct find_name_by_ino {
struct dir_context ctx;
int called, found;
ino_t ino;
char *name;
int namelen;
};
static int
find_name_by_ino(struct dir_context *ctx, const char *name, int namelen,
loff_t offset, u64 ino, unsigned int d_type)
{
struct find_name_by_ino *a = container_of(ctx, struct find_name_by_ino,
ctx);
a->called++;
if (a->ino != ino)
return 0;
memcpy(a->name, name, namelen);
a->namelen = namelen;
a->found = 1;
return 1;
}
static struct dentry *au_lkup_by_ino(struct path *path, ino_t ino,
struct au_nfsd_si_lock *nsi_lock)
{
struct dentry *dentry, *parent;
struct file *file;
struct inode *dir;
struct find_name_by_ino arg = {
.ctx = {
.actor = find_name_by_ino
}
};
int err;
parent = path->dentry;
if (nsi_lock)
si_read_unlock(parent->d_sb);
file = vfsub_dentry_open(path, au_dir_roflags);
dentry = (void *)file;
if (IS_ERR(file))
goto out;
dentry = ERR_PTR(-ENOMEM);
arg.name = (void *)__get_free_page(GFP_NOFS);
if (unlikely(!arg.name))
goto out_file;
arg.ino = ino;
arg.found = 0;
do {
arg.called = 0;
/* smp_mb(); */
err = vfsub_iterate_dir(file, &arg.ctx);
} while (!err && !arg.found && arg.called);
dentry = ERR_PTR(err);
if (unlikely(err))
goto out_name;
/* instead of ENOENT */
dentry = ERR_PTR(-ESTALE);
if (!arg.found)
goto out_name;
/* do not call vfsub_lkup_one() */
dir = d_inode(parent);
dentry = vfsub_lookup_one_len_unlocked(arg.name, parent, arg.namelen);
AuTraceErrPtr(dentry);
if (IS_ERR(dentry))
goto out_name;
AuDebugOn(au_test_anon(dentry));
if (unlikely(d_really_is_negative(dentry))) {
dput(dentry);
dentry = ERR_PTR(-ENOENT);
}
out_name:
au_delayed_free_page((unsigned long)arg.name);
out_file:
fput(file);
out:
if (unlikely(nsi_lock
&& si_nfsd_read_lock(parent->d_sb, nsi_lock) < 0))
if (!IS_ERR(dentry)) {
dput(dentry);
dentry = ERR_PTR(-ESTALE);
}
AuTraceErrPtr(dentry);
return dentry;
}
static struct dentry *decode_by_dir_ino(struct super_block *sb, ino_t ino,
ino_t dir_ino,
struct au_nfsd_si_lock *nsi_lock)
{
struct dentry *dentry;
struct path path;
if (dir_ino != AUFS_ROOT_INO) {
path.dentry = decode_by_ino(sb, dir_ino, 0);
dentry = path.dentry;
if (!path.dentry || IS_ERR(path.dentry))
goto out;
AuDebugOn(au_test_anon(path.dentry));
} else
path.dentry = dget(sb->s_root);
path.mnt = au_mnt_get(sb);
dentry = au_lkup_by_ino(&path, ino, nsi_lock);
path_put(&path);
out:
AuTraceErrPtr(dentry);
return dentry;
}
/* ---------------------------------------------------------------------- */
static int h_acceptable(void *expv, struct dentry *dentry)
{
return 1;
}
static char *au_build_path(struct dentry *h_parent, struct path *h_rootpath,
char *buf, int len, struct super_block *sb)
{
char *p;
int n;
struct path path;
p = d_path(h_rootpath, buf, len);
if (IS_ERR(p))
goto out;
n = strlen(p);
path.mnt = h_rootpath->mnt;
path.dentry = h_parent;
p = d_path(&path, buf, len);
if (IS_ERR(p))
goto out;
if (n != 1)
p += n;
path.mnt = au_mnt_get(sb);
path.dentry = sb->s_root;
p = d_path(&path, buf, len - strlen(p));
mntput(path.mnt);
if (IS_ERR(p))
goto out;
if (n != 1)
p[strlen(p)] = '/';
out:
AuTraceErrPtr(p);
return p;
}
static
struct dentry *decode_by_path(struct super_block *sb, ino_t ino, __u32 *fh,
int fh_len, struct au_nfsd_si_lock *nsi_lock)
{
struct dentry *dentry, *h_parent, *root;
struct super_block *h_sb;
char *pathname, *p;
struct vfsmount *h_mnt;
struct au_branch *br;
int err;
struct path path;
br = au_sbr(sb, nsi_lock->bindex);
h_mnt = au_br_mnt(br);
h_sb = h_mnt->mnt_sb;
/* todo: call lower fh_to_dentry()? fh_to_parent()? */
lockdep_off();
h_parent = exportfs_decode_fh(h_mnt, (void *)(fh + Fh_tail),
fh_len - Fh_tail, fh[Fh_h_type],
h_acceptable, /*context*/NULL);
lockdep_on();
dentry = h_parent;
if (unlikely(!h_parent || IS_ERR(h_parent))) {
AuWarn1("%s decode_fh failed, %ld\n",
au_sbtype(h_sb), PTR_ERR(h_parent));
goto out;
}
dentry = NULL;
if (unlikely(au_test_anon(h_parent))) {
AuWarn1("%s decode_fh returned a disconnected dentry\n",
au_sbtype(h_sb));
goto out_h_parent;
}
dentry = ERR_PTR(-ENOMEM);
pathname = (void *)__get_free_page(GFP_NOFS);
if (unlikely(!pathname))
goto out_h_parent;
root = sb->s_root;
path.mnt = h_mnt;
di_read_lock_parent(root, !AuLock_IR);
path.dentry = au_h_dptr(root, nsi_lock->bindex);
di_read_unlock(root, !AuLock_IR);
p = au_build_path(h_parent, &path, pathname, PAGE_SIZE, sb);
dentry = (void *)p;
if (IS_ERR(p))
goto out_pathname;
si_read_unlock(sb);
err = vfsub_kern_path(p, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
dentry = ERR_PTR(err);
if (unlikely(err))
goto out_relock;
dentry = ERR_PTR(-ENOENT);
AuDebugOn(au_test_anon(path.dentry));
if (unlikely(d_really_is_negative(path.dentry)))
goto out_path;
if (ino != d_inode(path.dentry)->i_ino)
dentry = au_lkup_by_ino(&path, ino, /*nsi_lock*/NULL);
else
dentry = dget(path.dentry);
out_path:
path_put(&path);
out_relock:
if (unlikely(si_nfsd_read_lock(sb, nsi_lock) < 0))
if (!IS_ERR(dentry)) {
dput(dentry);
dentry = ERR_PTR(-ESTALE);
}
out_pathname:
au_delayed_free_page((unsigned long)pathname);
out_h_parent:
dput(h_parent);
out:
AuTraceErrPtr(dentry);
return dentry;
}
/* ---------------------------------------------------------------------- */
static struct dentry *
aufs_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len,
int fh_type)
{
struct dentry *dentry;
__u32 *fh = fid->raw;
struct au_branch *br;
ino_t ino, dir_ino;
struct au_nfsd_si_lock nsi_lock = {
.force_lock = 0
};
dentry = ERR_PTR(-ESTALE);
/* it should never happen, but the file handle is unreliable */
if (unlikely(fh_len < Fh_tail))
goto out;
nsi_lock.sigen = fh[Fh_sigen];
nsi_lock.br_id = fh[Fh_br_id];
/* branch id may be wrapped around */
br = NULL;
if (unlikely(si_nfsd_read_lock(sb, &nsi_lock)))
goto out;
nsi_lock.force_lock = 1;
/* is this inode still cached? */
ino = decode_ino(fh + Fh_ino);
/* it should never happen */
if (unlikely(ino == AUFS_ROOT_INO))
goto out_unlock;
dir_ino = decode_ino(fh + Fh_dir_ino);
dentry = decode_by_ino(sb, ino, dir_ino);
if (IS_ERR(dentry))
goto out_unlock;
if (dentry)
goto accept;
/* is the parent dir cached? */
br = au_sbr(sb, nsi_lock.bindex);
au_br_get(br);
dentry = decode_by_dir_ino(sb, ino, dir_ino, &nsi_lock);
if (IS_ERR(dentry))
goto out_unlock;
if (dentry)
goto accept;
/* lookup path */
dentry = decode_by_path(sb, ino, fh, fh_len, &nsi_lock);
if (IS_ERR(dentry))
goto out_unlock;
if (unlikely(!dentry))
/* todo?: make it ESTALE */
goto out_unlock;
accept:
if (!au_digen_test(dentry, au_sigen(sb))
&& d_inode(dentry)->i_generation == fh[Fh_igen])
goto out_unlock; /* success */
dput(dentry);
dentry = ERR_PTR(-ESTALE);
out_unlock:
if (br)
au_br_put(br);
si_read_unlock(sb);
out:
AuTraceErrPtr(dentry);
return dentry;
}
#if 0 /* reserved for future use */
/* support subtreecheck option */
static struct dentry *aufs_fh_to_parent(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
struct dentry *parent;
__u32 *fh = fid->raw;
ino_t dir_ino;
dir_ino = decode_ino(fh + Fh_dir_ino);
parent = decode_by_ino(sb, dir_ino, 0);
if (IS_ERR(parent))
goto out;
if (!parent)
parent = decode_by_path(sb, au_br_index(sb, fh[Fh_br_id]),
dir_ino, fh, fh_len);
out:
AuTraceErrPtr(parent);
return parent;
}
#endif
/* ---------------------------------------------------------------------- */
static int aufs_encode_fh(struct inode *inode, __u32 *fh, int *max_len,
struct inode *dir)
{
int err;
aufs_bindex_t bindex;
struct super_block *sb, *h_sb;
struct dentry *dentry, *parent, *h_parent;
struct inode *h_dir;
struct au_branch *br;
err = -ENOSPC;
if (unlikely(*max_len <= Fh_tail)) {
AuWarn1("NFSv2 client (max_len %d)?\n", *max_len);
goto out;
}
err = FILEID_ROOT;
if (inode->i_ino == AUFS_ROOT_INO) {
AuDebugOn(inode->i_ino != AUFS_ROOT_INO);
goto out;
}
h_parent = NULL;
sb = inode->i_sb;
err = si_read_lock(sb, AuLock_FLUSH);
if (unlikely(err))
goto out;
#ifdef CONFIG_AUFS_DEBUG
if (unlikely(!au_opt_test(au_mntflags(sb), XINO)))
AuWarn1("NFS-exporting requires xino\n");
#endif
err = -EIO;
parent = NULL;
ii_read_lock_child(inode);
bindex = au_ibtop(inode);
if (!dir) {
dentry = d_find_any_alias(inode);
if (unlikely(!dentry))
goto out_unlock;
AuDebugOn(au_test_anon(dentry));
parent = dget_parent(dentry);
dput(dentry);
if (unlikely(!parent))
goto out_unlock;
if (d_really_is_positive(parent))
dir = d_inode(parent);
}
ii_read_lock_parent(dir);
h_dir = au_h_iptr(dir, bindex);
ii_read_unlock(dir);
if (unlikely(!h_dir))
goto out_parent;
h_parent = d_find_any_alias(h_dir);
if (unlikely(!h_parent))
goto out_hparent;
err = -EPERM;
br = au_sbr(sb, bindex);
h_sb = au_br_sb(br);
if (unlikely(!h_sb->s_export_op)) {
AuErr1("%s branch is not exportable\n", au_sbtype(h_sb));
goto out_hparent;
}
fh[Fh_br_id] = br->br_id;
fh[Fh_sigen] = au_sigen(sb);
encode_ino(fh + Fh_ino, inode->i_ino);
encode_ino(fh + Fh_dir_ino, dir->i_ino);
fh[Fh_igen] = inode->i_generation;
*max_len -= Fh_tail;
fh[Fh_h_type] = exportfs_encode_fh(h_parent, (void *)(fh + Fh_tail),
max_len,
/*connectable or subtreecheck*/0);
err = fh[Fh_h_type];
*max_len += Fh_tail;
/* todo: macros? */
if (err != FILEID_INVALID)
err = 99;
else
AuWarn1("%s encode_fh failed\n", au_sbtype(h_sb));
out_hparent:
dput(h_parent);
out_parent:
dput(parent);
out_unlock:
ii_read_unlock(inode);
si_read_unlock(sb);
out:
if (unlikely(err < 0))
err = FILEID_INVALID;
return err;
}
/* ---------------------------------------------------------------------- */
static int aufs_commit_metadata(struct inode *inode)
{
int err;
aufs_bindex_t bindex;
struct super_block *sb;
struct inode *h_inode;
int (*f)(struct inode *inode);
sb = inode->i_sb;
si_read_lock(sb, AuLock_FLUSH | AuLock_NOPLMW);
ii_write_lock_child(inode);
bindex = au_ibtop(inode);
AuDebugOn(bindex < 0);
h_inode = au_h_iptr(inode, bindex);
f = h_inode->i_sb->s_export_op->commit_metadata;
if (f)
err = f(h_inode);
else {
struct writeback_control wbc = {
.sync_mode = WB_SYNC_ALL,
.nr_to_write = 0 /* metadata only */
};
err = sync_inode(h_inode, &wbc);
}
au_cpup_attr_timesizes(inode);
ii_write_unlock(inode);
si_read_unlock(sb);
return err;
}
/* ---------------------------------------------------------------------- */
static struct export_operations aufs_export_op = {
.fh_to_dentry = aufs_fh_to_dentry,
/* .fh_to_parent = aufs_fh_to_parent, */
.encode_fh = aufs_encode_fh,
.commit_metadata = aufs_commit_metadata
};
void au_export_init(struct super_block *sb)
{
struct au_sbinfo *sbinfo;
__u32 u;
BUILD_BUG_ON_MSG(IS_BUILTIN(CONFIG_AUFS_FS)
&& IS_MODULE(CONFIG_EXPORTFS),
AUFS_NAME ": unsupported configuration "
"CONFIG_EXPORTFS=m and CONFIG_AUFS_FS=y");
sb->s_export_op = &aufs_export_op;
sbinfo = au_sbi(sb);
sbinfo->si_xigen = NULL;
get_random_bytes(&u, sizeof(u));
BUILD_BUG_ON(sizeof(u) != sizeof(int));
atomic_set(&sbinfo->si_xigen_next, u);
}
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