get rid of s_files and files_lock

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>
[sw0312.kim: cherry-pick from linux-3.10.y to fix CVE-2014-8172]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: Id0c1179c0f3b250c2a2928ff816aa080dd10c117

diff --git a/fs/file_table.c b/fs/file_table.c
index cd4ef34..28f02a7 100644 (file)
--- 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 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 6812158..2ffa65a 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -74,9 +74,6 @@ 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 86092bd..5f12968 100644 (file)
--- 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)) {
                        /*

diff --git a/fs/super.c b/fs/super.c
index e028b50..97280e7 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -163,19 +163,6 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags)
                        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, 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 5d02413..b92d11f 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -762,12 +762,7 @@ 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 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 */