/usr/src/aufs-4.9+20161219/fs/aufs/dynop.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) 2010-2016 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/>.
*/
/*
* dynamically customizable operations for regular files
*/
#include "aufs.h"
#define DyPrSym(key) AuDbgSym(key->dk_op.dy_hop)
/*
* How large will these lists be?
* Usually just a few elements, 20-30 at most for each, I guess.
*/
static struct au_sphlhead dynop[AuDyLast];
static struct au_dykey *dy_gfind_get(struct au_sphlhead *sphl, const void *h_op)
{
struct au_dykey *key, *tmp;
struct hlist_head *head;
key = NULL;
head = &sphl->head;
rcu_read_lock();
hlist_for_each_entry_rcu(tmp, head, dk_hnode)
if (tmp->dk_op.dy_hop == h_op) {
key = tmp;
kref_get(&key->dk_kref);
break;
}
rcu_read_unlock();
return key;
}
static struct au_dykey *dy_bradd(struct au_branch *br, struct au_dykey *key)
{
struct au_dykey **k, *found;
const void *h_op = key->dk_op.dy_hop;
int i;
found = NULL;
k = br->br_dykey;
for (i = 0; i < AuBrDynOp; i++)
if (k[i]) {
if (k[i]->dk_op.dy_hop == h_op) {
found = k[i];
break;
}
} else
break;
if (!found) {
spin_lock(&br->br_dykey_lock);
for (; i < AuBrDynOp; i++)
if (k[i]) {
if (k[i]->dk_op.dy_hop == h_op) {
found = k[i];
break;
}
} else {
k[i] = key;
break;
}
spin_unlock(&br->br_dykey_lock);
BUG_ON(i == AuBrDynOp); /* expand the array */
}
return found;
}
/* kref_get() if @key is already added */
static struct au_dykey *dy_gadd(struct au_sphlhead *sphl, struct au_dykey *key)
{
struct au_dykey *tmp, *found;
struct hlist_head *head;
const void *h_op = key->dk_op.dy_hop;
found = NULL;
head = &sphl->head;
spin_lock(&sphl->spin);
hlist_for_each_entry(tmp, head, dk_hnode)
if (tmp->dk_op.dy_hop == h_op) {
kref_get(&tmp->dk_kref);
found = tmp;
break;
}
if (!found)
hlist_add_head_rcu(&key->dk_hnode, head);
spin_unlock(&sphl->spin);
if (!found)
DyPrSym(key);
return found;
}
static void dy_free_rcu(struct rcu_head *rcu)
{
struct au_dykey *key;
key = container_of(rcu, struct au_dykey, dk_rcu);
DyPrSym(key);
kfree(key); /* not delayed */
}
static void dy_free(struct kref *kref)
{
struct au_dykey *key;
struct au_sphlhead *sphl;
key = container_of(kref, struct au_dykey, dk_kref);
sphl = dynop + key->dk_op.dy_type;
au_sphl_del_rcu(&key->dk_hnode, sphl);
call_rcu(&key->dk_rcu, dy_free_rcu);
}
void au_dy_put(struct au_dykey *key)
{
kref_put(&key->dk_kref, dy_free);
}
/* ---------------------------------------------------------------------- */
#define DyDbgSize(cnt, op) AuDebugOn(cnt != sizeof(op)/sizeof(void *))
#ifdef CONFIG_AUFS_DEBUG
#define DyDbgDeclare(cnt) unsigned int cnt = 0
#define DyDbgInc(cnt) do { cnt++; } while (0)
#else
#define DyDbgDeclare(cnt) do {} while (0)
#define DyDbgInc(cnt) do {} while (0)
#endif
#define DySet(func, dst, src, h_op, h_sb) do { \
DyDbgInc(cnt); \
if (h_op->func) { \
if (src.func) \
dst.func = src.func; \
else \
AuDbg("%s %s\n", au_sbtype(h_sb), #func); \
} \
} while (0)
#define DySetForce(func, dst, src) do { \
AuDebugOn(!src.func); \
DyDbgInc(cnt); \
dst.func = src.func; \
} while (0)
#define DySetAop(func) \
DySet(func, dyaop->da_op, aufs_aop, h_aop, h_sb)
#define DySetAopForce(func) \
DySetForce(func, dyaop->da_op, aufs_aop)
static void dy_aop(struct au_dykey *key, const void *h_op,
struct super_block *h_sb __maybe_unused)
{
struct au_dyaop *dyaop = (void *)key;
const struct address_space_operations *h_aop = h_op;
DyDbgDeclare(cnt);
AuDbg("%s\n", au_sbtype(h_sb));
DySetAop(writepage);
DySetAopForce(readpage); /* force */
DySetAop(writepages);
DySetAop(set_page_dirty);
DySetAop(readpages);
DySetAop(write_begin);
DySetAop(write_end);
DySetAop(bmap);
DySetAop(invalidatepage);
DySetAop(releasepage);
DySetAop(freepage);
/* this one will be changed according to an aufs mount option */
DySetAop(direct_IO);
DySetAop(migratepage);
DySetAop(isolate_page);
DySetAop(putback_page);
DySetAop(launder_page);
DySetAop(is_partially_uptodate);
DySetAop(is_dirty_writeback);
DySetAop(error_remove_page);
DySetAop(swap_activate);
DySetAop(swap_deactivate);
DyDbgSize(cnt, *h_aop);
}
/* ---------------------------------------------------------------------- */
static void dy_bug(struct kref *kref)
{
BUG();
}
static struct au_dykey *dy_get(struct au_dynop *op, struct au_branch *br)
{
struct au_dykey *key, *old;
struct au_sphlhead *sphl;
struct op {
unsigned int sz;
void (*set)(struct au_dykey *key, const void *h_op,
struct super_block *h_sb __maybe_unused);
};
static const struct op a[] = {
[AuDy_AOP] = {
.sz = sizeof(struct au_dyaop),
.set = dy_aop
}
};
const struct op *p;
sphl = dynop + op->dy_type;
key = dy_gfind_get(sphl, op->dy_hop);
if (key)
goto out_add; /* success */
p = a + op->dy_type;
key = kzalloc(p->sz, GFP_NOFS);
if (unlikely(!key)) {
key = ERR_PTR(-ENOMEM);
goto out;
}
key->dk_op.dy_hop = op->dy_hop;
kref_init(&key->dk_kref);
p->set(key, op->dy_hop, au_br_sb(br));
old = dy_gadd(sphl, key);
if (old) {
au_delayed_kfree(key);
key = old;
}
out_add:
old = dy_bradd(br, key);
if (old)
/* its ref-count should never be zero here */
kref_put(&key->dk_kref, dy_bug);
out:
return key;
}
/* ---------------------------------------------------------------------- */
/*
* Aufs prohibits O_DIRECT by defaut even if the branch supports it.
* This behaviour is necessary to return an error from open(O_DIRECT) instead
* of the succeeding I/O. The dio mount option enables O_DIRECT and makes
* open(O_DIRECT) always succeed, but the succeeding I/O may return an error.
* See the aufs manual in detail.
*/
static void dy_adx(struct au_dyaop *dyaop, int do_dx)
{
if (!do_dx)
dyaop->da_op.direct_IO = NULL;
else
dyaop->da_op.direct_IO = aufs_aop.direct_IO;
}
static struct au_dyaop *dy_aget(struct au_branch *br,
const struct address_space_operations *h_aop,
int do_dx)
{
struct au_dyaop *dyaop;
struct au_dynop op;
op.dy_type = AuDy_AOP;
op.dy_haop = h_aop;
dyaop = (void *)dy_get(&op, br);
if (IS_ERR(dyaop))
goto out;
dy_adx(dyaop, do_dx);
out:
return dyaop;
}
int au_dy_iaop(struct inode *inode, aufs_bindex_t bindex,
struct inode *h_inode)
{
int err, do_dx;
struct super_block *sb;
struct au_branch *br;
struct au_dyaop *dyaop;
AuDebugOn(!S_ISREG(h_inode->i_mode));
IiMustWriteLock(inode);
sb = inode->i_sb;
br = au_sbr(sb, bindex);
do_dx = !!au_opt_test(au_mntflags(sb), DIO);
dyaop = dy_aget(br, h_inode->i_mapping->a_ops, do_dx);
err = PTR_ERR(dyaop);
if (IS_ERR(dyaop))
/* unnecessary to call dy_fput() */
goto out;
err = 0;
inode->i_mapping->a_ops = &dyaop->da_op;
out:
return err;
}
/*
* Is it safe to replace a_ops during the inode/file is in operation?
* Yes, I hope so.
*/
int au_dy_irefresh(struct inode *inode)
{
int err;
aufs_bindex_t btop;
struct inode *h_inode;
err = 0;
if (S_ISREG(inode->i_mode)) {
btop = au_ibtop(inode);
h_inode = au_h_iptr(inode, btop);
err = au_dy_iaop(inode, btop, h_inode);
}
return err;
}
void au_dy_arefresh(int do_dx)
{
struct au_sphlhead *sphl;
struct hlist_head *head;
struct au_dykey *key;
sphl = dynop + AuDy_AOP;
head = &sphl->head;
spin_lock(&sphl->spin);
hlist_for_each_entry(key, head, dk_hnode)
dy_adx((void *)key, do_dx);
spin_unlock(&sphl->spin);
}
/* ---------------------------------------------------------------------- */
void __init au_dy_init(void)
{
int i;
/* make sure that 'struct au_dykey *' can be any type */
BUILD_BUG_ON(offsetof(struct au_dyaop, da_key));
for (i = 0; i < AuDyLast; i++)
au_sphl_init(dynop + i);
}
void au_dy_fin(void)
{
int i;
for (i = 0; i < AuDyLast; i++)
WARN_ON(!hlist_empty(&dynop[i].head));
}
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