kernel/git/torvalds/linux.git - Linux kernel source tree

Age	Commit message (Expand)	Author	Files	Lines
2006-06-26	[PATCH] Add new generic HW RNG core	Michael Buesch	1	-0/+5

/* * linux/fs/file_table.c * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu) */ #include <linux/string.h> #include <linux/slab.h> #include <linux/file.h> #include <linux/init.h> #include <linux/module.h> #include <linux/smp_lock.h> #include <linux/fs.h> #include <linux/security.h> #include <linux/eventpoll.h> #include <linux/rcupdate.h> #include <linux/mount.h> #include <linux/cdev.h> #include <linux/fsnotify.h> /* sysctl tunables... */ struct files_stat_struct files_stat = { .max_files = NR_FILE }; EXPORT_SYMBOL(files_stat); /* Needed by unix.o */ /* public. Not pretty! */ __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); static DEFINE_SPINLOCK(filp_count_lock); /* slab constructors and destructors are called from arbitrary * context and must be fully threaded - use a local spinlock * to protect files_stat.nr_files */ void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags) { if ((cflags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) { unsigned long flags; spin_lock_irqsave(&filp_count_lock, flags); files_stat.nr_files++; spin_unlock_irqrestore(&filp_count_lock, flags); } } void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags) { unsigned long flags; spin_lock_irqsave(&filp_count_lock, flags); files_stat.nr_files--; spin_unlock_irqrestore(&filp_count_lock, flags); } static inline void file_free_rcu(struct rcu_head *head) { struct file *f = container_of(head, struct file, f_rcuhead); kmem_cache_free(filp_cachep, f); } static inline void file_free(struct file *f) { call_rcu(&f->f_rcuhead, file_free_rcu); } /* Find an unused file structure and return a pointer to it. * Returns NULL, if there are no more free file structures or * we run out of memory. */ struct file *get_empty_filp(void) { static int old_max; struct file * f; /* * Privileged users can go above max_files */ if (files_stat.nr_files >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) goto over; f = kmem_cache_alloc(filp_cachep, GFP_KERNEL); if (f == NULL) goto fail; memset(f, 0, sizeof(*f)); if (security_file_alloc(f)) goto fail_sec; eventpoll_init_file(f); atomic_set(&f->f_count, 1); f->f_uid = current->fsuid; f->f_gid = current->fsgid; rwlock_init(&f->f_owner.lock); /* f->f_version: 0 */ INIT_LIST_HEAD(&f->f_list); return f; over: /* Ran out of filps - report that */ if (files_stat.nr_files > old_max) { printk(KERN_INFO "VFS: file-max limit %d reached\n", files_stat.max_files); old_max = files_stat.nr_files; } goto fail; fail_sec: file_free(f); fail: return NULL; } EXPORT_SYMBOL(get_empty_filp); void fastcall fput(struct file *file) { if (rcuref_dec_and_test(&file->f_count)) __fput(file); } EXPORT_SYMBOL(fput); /* __fput is called from task context when aio completion releases the last * last use of a struct file *. Do not use otherwise. */ void fastcall __fput(struct file *file) { struct dentry *dentry = file->f_dentry; struct vfsmount *mnt = file->f_vfsmnt; struct inode *inode = dentry->d_inode; might_sleep(); fsnotify_close(file); /* * The function eventpoll_release() should be the first called * in the file cleanup chain. */ eventpoll_release(file); locks_remove_flock(file); if (file->f_op && file->f_op->release) file->f_op->release(inode, file); security_file_free(file); if (unlikely(inode->i_cdev != NULL)) cdev_put(inode->i_cdev); fops_put(file->f_op); if (file->f_mode & FMODE_WRITE) put_write_access(inode); file_kill(file); file->f_dentry = NULL; file->f_vfsmnt = NULL; file_free(file); dput(dentry); mntput(mnt); } struct file fastcall *fget(unsigned int fd) { struct file *file; struct files_struct *files = current->files; rcu_read_lock(); file = fcheck_files(files, fd); if (file) { if (!rcuref_inc_lf(&file->f_count)) { /* File object ref couldn't be taken */ rcu_read_unlock(); return NULL; } } rcu_read_unlock(); return file; } 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. */ struct file fastcall *fget_light(unsigned int fd, int *fput_needed) { struct file *file; struct files_struct *files = current->files; *fput_needed = 0; if (likely((atomic_read(&files->count) == 1))) { file = fcheck_files(files, fd); } else { rcu_read_lock(); file = fcheck_files(files, fd); if (file) { if (rcuref_inc_lf(&file->f_count)) *fput_needed = 1; else /* Didn't get the reference, someone's freed */ file = NULL; } rcu_read_unlock(); } return file; } void put_filp(struct file *file) { if (rcuref_dec_and_test(&file->f_count)) { security_file_free(file); file_kill(file); file_free(file); } } void file_move(struct file *file, struct list_head *list) { if (!list) return; file_list_lock(); list_move(&file->f_list, list); file_list_unlock(); } void file_kill(struct file *file) { if (!list_empty(&file->f_list)) { file_list_lock(); list_del_init(&file->f_list); file_list_unlock(); } } int fs_may_remount_ro(struct super_block *sb) { struct list_head *p; /* Check that no files are currently opened for writing. */ file_list_lock(); list_for_each(p, &sb->s_files) { struct file *file = list_entry(p, struct file, f_list); struct inode *inode = file->f_dentry->d_inode; /* File with pending delete? */ if (inode->i_nlink == 0) goto too_bad; /* Writeable file? */ if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE)) goto too_bad; } file_list_unlock(); return 1; /* Tis' cool bro. */ too_bad: file_list_unlock(); return 0; } void __init files_init(unsigned long mempages) { int n; /* One file with associated inode and dcache is very roughly 1K. * Per default don't use more than 10% of our memory for files. */ n = (mempages * (PAGE_SIZE / 1024)) / 10; files_stat.max_files = n; if (files_stat.max_files < NR_FILE) files_stat.max_files = NR_FILE; files_defer_init(); }