--- /dev/null
+/*
+ * Copyright (C) 2010-2011 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/*
+ * 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_splhead dynop[AuDyLast];
+
+static struct au_dykey *dy_gfind_get(struct au_splhead *spl, const void *h_op)
+{
+ struct au_dykey *key, *tmp;
+ struct list_head *head;
+
+ key = NULL;
+ head = &spl->head;
+ rcu_read_lock();
+ list_for_each_entry_rcu(tmp, head, dk_list)
+ 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_splhead *spl, struct au_dykey *key)
+{
+ struct au_dykey *tmp, *found;
+ struct list_head *head;
+ const void *h_op = key->dk_op.dy_hop;
+
+ found = NULL;
+ head = &spl->head;
+ spin_lock(&spl->spin);
+ list_for_each_entry(tmp, head, dk_list)
+ if (tmp->dk_op.dy_hop == h_op) {
+ kref_get(&tmp->dk_kref);
+ found = tmp;
+ break;
+ }
+ if (!found)
+ list_add_rcu(&key->dk_list, head);
+ spin_unlock(&spl->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);
+}
+
+static void dy_free(struct kref *kref)
+{
+ struct au_dykey *key;
+ struct au_splhead *spl;
+
+ key = container_of(kref, struct au_dykey, dk_kref);
+ spl = dynop + key->dk_op.dy_type;
+ au_spl_del_rcu(&key->dk_list, spl);
+ 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);
+ /* these two will be changed according to an aufs mount option */
+ DySetAop(direct_IO);
+ DySetAop(get_xip_mem);
+ DySetAop(migratepage);
+ DySetAop(launder_page);
+ DySetAop(is_partially_uptodate);
+ DySetAop(error_remove_page);
+
+ DyDbgSize(cnt, *h_aop);
+ dyaop->da_get_xip_mem = h_aop->get_xip_mem;
+}
+
+#define DySetVmop(func) \
+ DySet(func, dyvmop->dv_op, aufs_vm_ops, h_vmop, h_sb)
+#define DySetVmopForce(func) \
+ DySetForce(func, dyvmop->dv_op, aufs_vm_ops)
+
+static void dy_vmop(struct au_dykey *key, const void *h_op,
+ struct super_block *h_sb __maybe_unused)
+{
+ struct au_dyvmop *dyvmop = (void *)key;
+ const struct vm_operations_struct *h_vmop = h_op;
+ DyDbgDeclare(cnt);
+
+ AuDbg("%s\n", au_sbtype(h_sb));
+
+ DySetVmop(open);
+ DySetVmop(close);
+ DySetVmop(fault);
+ DySetVmop(page_mkwrite);
+ DySetVmop(access);
+#ifdef CONFIG_NUMA
+ DySetVmop(set_policy);
+ DySetVmop(get_policy);
+ DySetVmop(migrate);
+#endif
+
+ DyDbgSize(cnt, *h_vmop);
+}
+
+/* ---------------------------------------------------------------------- */
+
+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_splhead *spl;
+ 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
+ },
+ [AuDy_VMOP] = {
+ .sz = sizeof(struct au_dyvmop),
+ .set = dy_vmop
+ }
+ };
+ const struct op *p;
+
+ spl = dynop + op->dy_type;
+ key = dy_gfind_get(spl, 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, br->br_mnt->mnt_sb);
+ old = dy_gadd(spl, key);
+ if (old) {
+ 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 neccessary 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.
+ *
+ * To keep this behaviour, aufs has to set NULL to ->get_xip_mem too, and the
+ * performance of fadvise() and madvise() may be affected.
+ */
+static void dy_adx(struct au_dyaop *dyaop, int do_dx)
+{
+ if (!do_dx) {
+ dyaop->da_op.direct_IO = NULL;
+ dyaop->da_op.get_xip_mem = NULL;
+ } else {
+ dyaop->da_op.direct_IO = aufs_aop.direct_IO;
+ dyaop->da_op.get_xip_mem = aufs_aop.get_xip_mem;
+ if (!dyaop->da_get_xip_mem)
+ dyaop->da_op.get_xip_mem = NULL;
+ }
+}
+
+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 bstart;
+ struct inode *h_inode;
+
+ err = 0;
+ if (S_ISREG(inode->i_mode)) {
+ bstart = au_ibstart(inode);
+ h_inode = au_h_iptr(inode, bstart);
+ err = au_dy_iaop(inode, bstart, h_inode);
+ }
+ return err;
+}
+
+void au_dy_arefresh(int do_dx)
+{
+ struct au_splhead *spl;
+ struct list_head *head;
+ struct au_dykey *key;
+
+ spl = dynop + AuDy_AOP;
+ head = &spl->head;
+ spin_lock(&spl->spin);
+ list_for_each_entry(key, head, dk_list)
+ dy_adx((void *)key, do_dx);
+ spin_unlock(&spl->spin);
+}
+
+const struct vm_operations_struct *
+au_dy_vmop(struct file *file, struct au_branch *br,
+ const struct vm_operations_struct *h_vmop)
+{
+ struct au_dyvmop *dyvmop;
+ struct au_dynop op;
+
+ op.dy_type = AuDy_VMOP;
+ op.dy_hvmop = h_vmop;
+ dyvmop = (void *)dy_get(&op, br);
+ if (IS_ERR(dyvmop))
+ return (void *)dyvmop;
+ return &dyvmop->dv_op;
+}
+
+/* ---------------------------------------------------------------------- */
+
+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));
+ BUILD_BUG_ON(offsetof(struct au_dyvmop, dv_key));
+
+ for (i = 0; i < AuDyLast; i++)
+ au_spl_init(dynop + i);
+}
+
+void au_dy_fin(void)
+{
+ int i;
+
+ for (i = 0; i < AuDyLast; i++)
+ WARN_ON(!list_empty(&dynop[i].head));
+}
git.openpandora.org / pandora-kernel.git / blobdiff