[PATCH 3.10 02/22] get rid of s_files and files_lock

Greg Kroah-Hartman
2015-07-01T18:53:39Z

From: Al Viro <viro@zeniv.linux.org.uk>

commit eee5cc2702929fd41cce28058dc6d6717f723f87 upstream.

The only thing we need it for is alt-sysrq-r (emergency remount r/o)
and these days we can do just as well without going through the
list of files.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[wangkai: backport to 3.10: adjust context]
Signed-off-by: Wang Kai <morgan.wang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/file_table.c | 123 -----------------------------------------------------
fs/internal.h | 3 -
fs/open.c | 2
fs/super.c | 23 ---------
include/linux/fs.h | 13 -----
5 files changed, 2 insertions(+), 162 deletions(-)

--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -36,8 +36,6 @@ struct files_stat_struct files_stat = {
.max_files = NR_FILE
};

-DEFINE_STATIC_LGLOCK(files_lglock);
-
/* SLAB cache for file structures */
static struct kmem_cache *filp_cachep __read_mostly;

@@ -134,7 +132,6 @@ struct file *get_empty_filp(void)
return ERR_PTR(error);
}

- INIT_LIST_HEAD(&f->f_u.fu_list);
atomic_long_set(&f->f_count, 1);
rwlock_init(&f->f_owner.lock);
spin_lock_init(&f->f_lock);
@@ -304,7 +301,6 @@ void fput(struct file *file)
if (atomic_long_dec_and_test(&file->f_count)) {
struct task_struct *task = current;

- file_sb_list_del(file);
if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
init_task_work(&file->f_u.fu_rcuhead, ____fput);
if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
@@ -328,7 +324,6 @@ void __fput_sync(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
struct task_struct *task = current;
- file_sb_list_del(file);
BUG_ON(!(task->flags & PF_KTHREAD));
__fput(file);
}
@@ -340,127 +335,10 @@ void put_filp(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
security_file_free(file);
- file_sb_list_del(file);
file_free(file);
}
}

-static inline int file_list_cpu(struct file *file)
-{
-#ifdef CONFIG_SMP
- return file->f_sb_list_cpu;
-#else
- return smp_processor_id();
-#endif
-}
-
-/* helper for file_sb_list_add to reduce ifdefs */
-static inline void __file_sb_list_add(struct file *file, struct super_block *sb)
-{
- struct list_head *list;
-#ifdef CONFIG_SMP
- int cpu;
- cpu = smp_processor_id();
- file->f_sb_list_cpu = cpu;
- list = per_cpu_ptr(sb->s_files, cpu);
-#else
- list = &sb->s_files;
-#endif
- list_add(&file->f_u.fu_list, list);
-}
-
-/**
- * file_sb_list_add - add a file to the sb's file list
- * @file: file to add
- * @sb: sb to add it to
- *
- * Use this function to associate a file with the superblock of the inode it
- * refers to.
- */
-void file_sb_list_add(struct file *file, struct super_block *sb)
-{
- lg_local_lock(&files_lglock);
- __file_sb_list_add(file, sb);
- lg_local_unlock(&files_lglock);
-}
-
-/**
- * file_sb_list_del - remove a file from the sb's file list
- * @file: file to remove
- * @sb: sb to remove it from
- *
- * Use this function to remove a file from its superblock.
- */
-void file_sb_list_del(struct file *file)
-{
- if (!list_empty(&file->f_u.fu_list)) {
- lg_local_lock_cpu(&files_lglock, file_list_cpu(file));
- list_del_init(&file->f_u.fu_list);
- lg_local_unlock_cpu(&files_lglock, file_list_cpu(file));
- }
-}
-
-#ifdef CONFIG_SMP
-
-/*
- * These macros iterate all files on all CPUs for a given superblock.
- * files_lglock must be held globally.
- */
-#define do_file_list_for_each_entry(__sb, __file) \
-{ \
- int i; \
- for_each_possible_cpu(i) { \
- struct list_head *list; \
- list = per_cpu_ptr((__sb)->s_files, i); \
- list_for_each_entry((__file), list, f_u.fu_list)
-
-#define while_file_list_for_each_entry \
- } \
-}
-
-#else
-
-#define do_file_list_for_each_entry(__sb, __file) \
-{ \
- struct list_head *list; \
- list = &(sb)->s_files; \
- list_for_each_entry((__file), list, f_u.fu_list)
-
-#define while_file_list_for_each_entry \
-}
-
-#endif
-
-/**
- * mark_files_ro - mark all files read-only
- * @sb: superblock in question
- *
- * All files are marked read-only. We don't care about pending
- * delete files so this should be used in 'force' mode only.
- */
-void mark_files_ro(struct super_block *sb)
-{
- struct file *f;
-
- lg_global_lock(&files_lglock);
- do_file_list_for_each_entry(sb, f) {
- if (!S_ISREG(file_inode(f)->i_mode))
- continue;
- if (!file_count(f))
- continue;
- if (!(f->f_mode & FMODE_WRITE))
- continue;
- spin_lock(&f->f_lock);
- f->f_mode &= ~FMODE_WRITE;
- spin_unlock(&f->f_lock);
- if (file_check_writeable(f) != 0)
- continue;
- __mnt_drop_write(f->f_path.mnt);
- file_release_write(f);
- } while_file_list_for_each_entry;
- lg_global_unlock(&files_lglock);
-}
-
void __init files_init(unsigned long mempages)
{
unsigned long n;
@@ -476,6 +354,5 @@ void __init files_init(unsigned long mem
n = (mempages * (PAGE_SIZE / 1024)) / 10;
files_stat.max_files = max_t(unsigned long, n, NR_FILE);
files_defer_init();
- lg_lock_init(&files_lglock, "files_lglock");
percpu_counter_init(&nr_files, 0);
}
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -74,9 +74,6 @@ extern void chroot_fs_refs(const struct
/*
* file_table.c
*/
-extern void file_sb_list_add(struct file *f, struct super_block *sb);
-extern void file_sb_list_del(struct file *f);
-extern void mark_files_ro(struct super_block *);
extern struct file *get_empty_filp(void);

/*
--- a/fs/open.c
+++ b/fs/open.c
@@ -674,7 +674,6 @@ static int do_dentry_open(struct file *f
}

f->f_mapping = inode->i_mapping;
- file_sb_list_add(f, inode->i_sb);

if (unlikely(f->f_mode & FMODE_PATH)) {
f->f_op = &empty_fops;
@@ -709,7 +708,6 @@ static int do_dentry_open(struct file *f

cleanup_all:
fops_put(f->f_op);
- file_sb_list_del(f);
if (f->f_mode & FMODE_WRITE) {
if (!special_file(inode->i_mode)) {
/*
--- a/fs/super.c
+++ b/fs/super.c
@@ -163,19 +163,6 @@ static struct super_block *alloc_super(s
s = NULL;
goto out;
}
-#ifdef CONFIG_SMP
- s->s_files = alloc_percpu(struct list_head);
- if (!s->s_files)
- goto err_out;
- else {
- int i;
-
- for_each_possible_cpu(i)
- INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
- }
-#else
- INIT_LIST_HEAD(&s->s_files);
-#endif
if (init_sb_writers(s, type))
goto err_out;
s->s_flags = flags;
@@ -225,10 +212,6 @@ out:
return s;
err_out:
security_sb_free(s);
-#ifdef CONFIG_SMP
- if (s->s_files)
- free_percpu(s->s_files);
-#endif
destroy_sb_writers(s);
kfree(s);
s = NULL;
@@ -243,9 +226,6 @@ err_out:
*/
static inline void destroy_super(struct super_block *s)
{
-#ifdef CONFIG_SMP
- free_percpu(s->s_files);
-#endif
destroy_sb_writers(s);
security_sb_free(s);
WARN_ON(!list_empty(&s->s_mounts));
@@ -727,7 +707,8 @@ int do_remount_sb(struct super_block *sb
make sure there are no rw files opened */
if (remount_ro) {
if (force) {
- mark_files_ro(sb);
+ sb->s_readonly_remount = 1;
+ smp_wmb();
} else {
retval = sb_prepare_remount_readonly(sb);
if (retval)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -762,12 +762,7 @@ static inline int ra_has_index(struct fi
#define FILE_MNT_WRITE_RELEASED 2

struct file {
- /*
- * fu_list becomes invalid after file_free is called and queued via
- * fu_rcuhead for RCU freeing
- */
union {
- struct list_head fu_list;
struct llist_node fu_llist;
struct rcu_head fu_rcuhead;
} f_u;
@@ -781,9 +776,6 @@ struct file {
* Must not be taken from IRQ context.
*/
spinlock_t f_lock;
-#ifdef CONFIG_SMP
- int f_sb_list_cpu;
-#endif
atomic_long_t f_count;
unsigned int f_flags;
fmode_t f_mode;
@@ -1259,11 +1251,6 @@ struct super_block {

struct list_head s_inodes; /* all inodes */
struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */
-#ifdef CONFIG_SMP
- struct list_head __percpu *s_files;
-#else
- struct list_head s_files;
-#endif
struct list_head s_mounts; /* list of mounts; _not_ for fs use */
/* s_dentry_lru, s_nr_dentry_unused protected by dcache.c lru locks */
struct list_head s_dentry_lru; /* unused dentry lru */