diff options
Diffstat (limited to 'fs/file_table.c')
| -rw-r--r-- | fs/file_table.c | 143 |
1 files changed, 109 insertions, 34 deletions
diff --git a/fs/file_table.c b/fs/file_table.c index 5c7d10ead4ad..a04bdd81c11c 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -20,7 +20,9 @@ #include <linux/cdev.h> #include <linux/fsnotify.h> #include <linux/sysctl.h> +#include <linux/lglock.h> #include <linux/percpu_counter.h> +#include <linux/percpu.h> #include <linux/ima.h> #include <asm/atomic.h> @@ -32,8 +34,8 @@ struct files_stat_struct files_stat = { .max_files = NR_FILE }; -/* public. Not pretty! */ -__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); +DECLARE_LGLOCK(files_lglock); +DEFINE_LGLOCK(files_lglock); /* SLAB cache for file structures */ static struct kmem_cache *filp_cachep __read_mostly; @@ -249,7 +251,7 @@ static void __fput(struct file *file) cdev_put(inode->i_cdev); fops_put(file->f_op); put_pid(file->f_owner.pid); - file_kill(file); + file_sb_list_del(file); if (file->f_mode & FMODE_WRITE) drop_file_write_access(file); file->f_path.dentry = NULL; @@ -289,11 +291,20 @@ struct file *fget(unsigned int fd) EXPORT_SYMBOL(fget); /* - * Lightweight file lookup - no refcnt increment if fd table isn't shared. - * You can use this only if it is guranteed that the current task already - * holds a refcnt to that file. That check has to be done at fget() only - * and a flag is returned to be passed to the corresponding fput_light(). - * There must not be a cloning between an fget_light/fput_light pair. + * Lightweight file lookup - no refcnt increment if fd table isn't shared. + * + * You can use this instead of fget if you satisfy all of the following + * conditions: + * 1) You must call fput_light before exiting the syscall and returning control + * to userspace (i.e. you cannot remember the returned struct file * after + * returning to userspace). + * 2) You must not call filp_close on the returned struct file * in between + * calls to fget_light and fput_light. + * 3) You must not clone the current task in between the calls to fget_light + * and fput_light. + * + * The fput_needed flag returned by fget_light should be passed to the + * corresponding fput_light. */ struct file *fget_light(unsigned int fd, int *fput_needed) { @@ -319,41 +330,107 @@ struct file *fget_light(unsigned int fd, int *fput_needed) return file; } - void put_filp(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) { security_file_free(file); - file_kill(file); + file_sb_list_del(file); file_free(file); } } -void file_move(struct file *file, struct list_head *list) +static inline int file_list_cpu(struct file *file) { - if (!list) - return; - file_list_lock(); - list_move(&file->f_u.fu_list, list); - file_list_unlock(); +#ifdef CONFIG_SMP + return file->f_sb_list_cpu; +#else + return smp_processor_id(); +#endif } -void file_kill(struct file *file) +/* 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)) { - file_list_lock(); + lg_local_lock_cpu(files_lglock, file_list_cpu(file)); list_del_init(&file->f_u.fu_list); - file_list_unlock(); + 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 + int fs_may_remount_ro(struct super_block *sb) { struct file *file; - /* Check that no files are currently opened for writing. */ - file_list_lock(); - list_for_each_entry(file, &sb->s_files, f_u.fu_list) { + lg_global_lock(files_lglock); + do_file_list_for_each_entry(sb, file) { struct inode *inode = file->f_path.dentry->d_inode; /* File with pending delete? */ @@ -363,11 +440,11 @@ int fs_may_remount_ro(struct super_block *sb) /* Writeable file? */ if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE)) goto too_bad; - } - file_list_unlock(); + } while_file_list_for_each_entry; + lg_global_unlock(files_lglock); return 1; /* Tis' cool bro. */ too_bad: - file_list_unlock(); + lg_global_unlock(files_lglock); return 0; } @@ -383,8 +460,8 @@ void mark_files_ro(struct super_block *sb) struct file *f; retry: - file_list_lock(); - list_for_each_entry(f, &sb->s_files, f_u.fu_list) { + 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; @@ -399,16 +476,13 @@ retry: continue; file_release_write(f); mnt = mntget(f->f_path.mnt); - file_list_unlock(); - /* - * This can sleep, so we can't hold - * the file_list_lock() spinlock. - */ + /* This can sleep, so we can't hold the spinlock. */ + lg_global_unlock(files_lglock); mnt_drop_write(mnt); mntput(mnt); goto retry; - } - file_list_unlock(); + } while_file_list_for_each_entry; + lg_global_unlock(files_lglock); } void __init files_init(unsigned long mempages) @@ -428,5 +502,6 @@ void __init files_init(unsigned long mempages) if (files_stat.max_files < NR_FILE) files_stat.max_files = NR_FILE; files_defer_init(); + lg_lock_init(files_lglock); percpu_counter_init(&nr_files, 0); } |