[PATCH] reduce sizeof(struct file)
Now that RCU applied on 'struct file' seems stable, we can place f_rcuhead
in a memory location that is not anymore used at call_rcu(&f->f_rcuhead,
file_free_rcu) time, to reduce the size of this critical kernel object.
The trick I used is to move f_rcuhead and f_list in an union called f_u
The callers are changed so that f_rcuhead becomes f_u.fu_rcuhead and f_list
becomes f_u.f_list
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index f5649a3..c586bfa 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -809,7 +809,7 @@
check_tty_count(tty, "do_tty_hangup");
file_list_lock();
/* This breaks for file handles being sent over AF_UNIX sockets ? */
- list_for_each_entry(filp, &tty->tty_files, f_list) {
+ list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
if (filp->f_op->write == redirected_tty_write)
cons_filp = filp;
if (filp->f_op->write != tty_write)
diff --git a/fs/dquot.c b/fs/dquot.c
index 05f3327..ea76442 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -662,7 +662,7 @@
restart:
file_list_lock();
list_for_each(p, &sb->s_files) {
- struct file *filp = list_entry(p, struct file, f_list);
+ struct file *filp = list_entry(p, struct file, f_u.fu_list);
struct inode *inode = filp->f_dentry->d_inode;
if (filp->f_mode & FMODE_WRITE && dqinit_needed(inode, type)) {
struct dentry *dentry = dget(filp->f_dentry);
diff --git a/fs/file_table.c b/fs/file_table.c
index 86ec8ae..4dc2055 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -56,13 +56,13 @@
static inline void file_free_rcu(struct rcu_head *head)
{
- struct file *f = container_of(head, struct file, f_rcuhead);
+ struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
kmem_cache_free(filp_cachep, f);
}
static inline void file_free(struct file *f)
{
- call_rcu(&f->f_rcuhead, file_free_rcu);
+ call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
}
/* Find an unused file structure and return a pointer to it.
@@ -95,7 +95,7 @@
f->f_gid = current->fsgid;
rwlock_init(&f->f_owner.lock);
/* f->f_version: 0 */
- INIT_LIST_HEAD(&f->f_list);
+ INIT_LIST_HEAD(&f->f_u.fu_list);
return f;
over:
@@ -225,15 +225,15 @@
if (!list)
return;
file_list_lock();
- list_move(&file->f_list, list);
+ list_move(&file->f_u.fu_list, list);
file_list_unlock();
}
void file_kill(struct file *file)
{
- if (!list_empty(&file->f_list)) {
+ if (!list_empty(&file->f_u.fu_list)) {
file_list_lock();
- list_del_init(&file->f_list);
+ list_del_init(&file->f_u.fu_list);
file_list_unlock();
}
}
@@ -245,7 +245,7 @@
/* Check that no files are currently opened for writing. */
file_list_lock();
list_for_each(p, &sb->s_files) {
- struct file *file = list_entry(p, struct file, f_list);
+ struct file *file = list_entry(p, struct file, f_u.fu_list);
struct inode *inode = file->f_dentry->d_inode;
/* File with pending delete? */
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 8a8c344..b638fb5 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -533,7 +533,7 @@
*/
file_list_lock();
list_for_each(p, &sb->s_files) {
- struct file * filp = list_entry(p, struct file, f_list);
+ struct file * filp = list_entry(p, struct file, f_u.fu_list);
struct dentry * dentry = filp->f_dentry;
struct inode * inode;
struct file_operations *fops;
diff --git a/fs/super.c b/fs/super.c
index 6e57ee2..f60155e 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -513,7 +513,7 @@
struct file *f;
file_list_lock();
- list_for_each_entry(f, &sb->s_files, f_list) {
+ list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
f->f_mode &= ~FMODE_WRITE;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f83d997..6d62267 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -574,7 +574,14 @@
#define RA_FLAG_INCACHE 0x02 /* file is already in cache */
struct file {
- struct list_head f_list;
+ /*
+ * fu_list becomes invalid after file_free is called and queued via
+ * fu_rcuhead for RCU freeing
+ */
+ union {
+ struct list_head fu_list;
+ struct rcu_head fu_rcuhead;
+ } f_u;
struct dentry *f_dentry;
struct vfsmount *f_vfsmnt;
struct file_operations *f_op;
@@ -598,7 +605,6 @@
spinlock_t f_ep_lock;
#endif /* #ifdef CONFIG_EPOLL */
struct address_space *f_mapping;
- struct rcu_head f_rcuhead;
};
extern spinlock_t files_lock;
#define file_list_lock() spin_lock(&files_lock);
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d50d7a7..bb62838 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1609,7 +1609,7 @@
if (tty) {
file_list_lock();
- file = list_entry(tty->tty_files.next, typeof(*file), f_list);
+ file = list_entry(tty->tty_files.next, typeof(*file), f_u.fu_list);
if (file) {
/* Revalidate access to controlling tty.
Use inode_has_perm on the tty inode directly rather
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 7a387fe..fdc3823 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -914,7 +914,7 @@
file_list_lock();
list_for_each(p, &sb->s_files) {
- struct file * filp = list_entry(p, struct file, f_list);
+ struct file * filp = list_entry(p, struct file, f_u.fu_list);
struct dentry * dentry = filp->f_dentry;
if (dentry->d_parent != de) {