[PATCH 3.4 090/107] get rid of s_files and files_lock

lizf
2016-03-16T08:18:52Z

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

3.4.111-rc1 review patch. If anyone has any objections, please let me know.

------------------

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>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
fs/file_table.c | 130 -----------------------------------------------------
fs/internal.h | 3 --
fs/open.c | 2 -
fs/super.c | 21 +--------
include/linux/fs.h | 13 ------
5 files changed, 2 insertions(+), 167 deletions(-)

diff --git a/fs/file_table.c b/fs/file_table.c
index 70f2a0f..a01710a 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -34,9 +34,6 @@ struct files_stat_struct files_stat = {
.max_files = NR_FILE
};

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

@@ -129,7 +126,6 @@ struct file *get_empty_filp(void)
if (security_file_alloc(f))
goto fail_sec;

- 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);
@@ -252,7 +248,6 @@ static void __fput(struct file *file)
}
fops_put(file->f_op);
put_pid(file->f_owner.pid);
- file_sb_list_del(file);
if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
i_readcount_dec(inode);
if (file->f_mode & FMODE_WRITE)
@@ -382,134 +377,10 @@ 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;
-
-retry:
- lg_global_lock(files_lglock);
- do_file_list_for_each_entry(sb, f) {
- struct vfsmount *mnt;
- if (!S_ISREG(f->f_path.dentry->d_inode->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;
- file_release_write(f);
- mnt = mntget(f->f_path.mnt);
- /* This can sleep, so we can't hold the spinlock. */
- lg_global_unlock(files_lglock);
- mnt_drop_write(mnt);
- mntput(mnt);
- goto retry;
- } while_file_list_for_each_entry;
- lg_global_unlock(files_lglock);
-}
-
void __init files_init(unsigned long mempages)
{
unsigned long n;
@@ -525,6 +396,5 @@ void __init files_init(unsigned long mempages)
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);
percpu_counter_init(&nr_files, 0);
}
diff --git a/fs/internal.h b/fs/internal.h
index 9962c59..ed005c5 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -67,9 +67,6 @@ extern void chroot_fs_refs(struct path *, struct path *);
/*
* 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);

/*
diff --git a/fs/open.c b/fs/open.c
index cf1d34f..703b051 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -672,7 +672,6 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_path.dentry = dentry;
f->f_path.mnt = mnt;
f->f_pos = 0;
- file_sb_list_add(f, inode->i_sb);

if (unlikely(f->f_mode & FMODE_PATH)) {
f->f_op = &empty_fops;
@@ -730,7 +729,6 @@ cleanup_all:
mnt_drop_write(mnt);
}
}
- file_sb_list_del(f);
f->f_path.dentry = NULL;
f->f_path.mnt = NULL;
cleanup_file:
diff --git a/fs/super.c b/fs/super.c
index d0154e5..36fbe27 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -122,22 +122,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
s = NULL;
goto out;
}
-#ifdef CONFIG_SMP
- s->s_files = alloc_percpu(struct list_head);
- if (!s->s_files) {
- security_sb_free(s);
- kfree(s);
- s = NULL;
- goto 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
s->s_bdi = &default_backing_dev_info;
INIT_HLIST_NODE(&s->s_instances);
INIT_HLIST_BL_HEAD(&s->s_anon);
@@ -200,9 +185,6 @@ out:
*/
static inline void destroy_super(struct super_block *s)
{
-#ifdef CONFIG_SMP
- free_percpu(s->s_files);
-#endif
security_sb_free(s);
WARN_ON(!list_empty(&s->s_mounts));
kfree(s->s_subtype);
@@ -744,7 +726,8 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
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)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 210c347..e7bbe99 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -976,12 +976,7 @@ static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
#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 rcu_head fu_rcuhead;
} f_u;
struct path f_path;
@@ -994,9 +989,6 @@ 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;
@@ -1443,11 +1435,6 @@ 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 */
--
1.9.1