get rid of s_files and files_lock

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>

4 files changed, 2 insertions, 143 deletions

diff --git a/fs/file_table.c b/fs/file_table.c
index e61e5529fa9d..23b6dca03ba0 100644
--- 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))
@@ -333,7 +329,6 @@ 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);
         }
@@ -345,129 +340,10 @@ 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)
-{
-        if (likely(!(file->f_mode & FMODE_WRITE)))
-                return;
-        if (!S_ISREG(file_inode(file)->i_mode))
-                return;
-        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 (!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;
@@ -483,6 +359,5 @@ 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, "files_lglock");
         percpu_counter_init(&nr_files, 0);
 } 
diff --git a/fs/internal.h b/fs/internal.h
index 4a11e75ce14d..465742407466 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -73,9 +73,6 @@ extern void chroot_fs_refs(const struct path *, const 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 a1465b1ec8c7..fffbed40dbe9 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -685,7 +685,6 @@ 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;
@@ -724,7 +723,6 @@ 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) {
                 put_write_access(inode);
                 if (!special_file(inode->i_mode)) {
diff --git a/fs/super.c b/fs/super.c
index 743bb7118053..e5f6c2cfac38 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -140,9 +140,6 @@ static void destroy_super(struct super_block *s)
         int i;
         list_lru_destroy(&s->s_dentry_lru);
         list_lru_destroy(&s->s_inode_lru);
-#ifdef CONFIG_SMP
-        free_percpu(s->s_files);
-#endif
         for (i = 0; i < SB_FREEZE_LEVELS; i++)
                 percpu_counter_destroy(&s->s_writers.counter[i]);
         security_sb_free(s);
@@ -172,15 +169,6 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
         if (security_sb_alloc(s))
                 goto fail;
 
-#ifdef CONFIG_SMP
-        s->s_files = alloc_percpu(struct list_head);
-        if (!s->s_files)
-                goto fail;
-        for_each_possible_cpu(i)
-                INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
-#else
-        INIT_LIST_HEAD(&s->s_files);
-#endif
         for (i = 0; i < SB_FREEZE_LEVELS; i++) {
                 if (percpu_counter_init(&s->s_writers.counter[i], 0) < 0)
                         goto fail;
@@ -722,7 +710,8 @@ 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)