ia64/linux-2.6.18-xen.hg

view fs/file_table.c @ 452:c7ed6fe5dca0

kexec: dont initialise regions in reserve_memory()

There is no need to initialise efi_memmap_res and boot_param_res in
reserve_memory() for the initial xen domain as it is done in
machine_kexec_setup_resources() using values from the kexec hypercall.

Signed-off-by: Simon Horman <horms@verge.net.au>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Feb 28 10:55:18 2008 +0000 (2008-02-28)
parents 831230e53067
children
line source
1 /*
2 * linux/fs/file_table.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
6 */
8 #include <linux/string.h>
9 #include <linux/slab.h>
10 #include <linux/file.h>
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/smp_lock.h>
14 #include <linux/fs.h>
15 #include <linux/security.h>
16 #include <linux/eventpoll.h>
17 #include <linux/rcupdate.h>
18 #include <linux/mount.h>
19 #include <linux/capability.h>
20 #include <linux/cdev.h>
21 #include <linux/fsnotify.h>
22 #include <linux/sysctl.h>
23 #include <linux/percpu_counter.h>
25 #include <asm/atomic.h>
27 /* sysctl tunables... */
28 struct files_stat_struct files_stat = {
29 .max_files = NR_FILE
30 };
32 /* public. Not pretty! */
33 __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
35 static struct percpu_counter nr_files __cacheline_aligned_in_smp;
37 static inline void file_free_rcu(struct rcu_head *head)
38 {
39 struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
40 kmem_cache_free(filp_cachep, f);
41 }
43 static inline void file_free(struct file *f)
44 {
45 percpu_counter_dec(&nr_files);
46 call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
47 }
49 /*
50 * Return the total number of open files in the system
51 */
52 static int get_nr_files(void)
53 {
54 return percpu_counter_read_positive(&nr_files);
55 }
57 /*
58 * Return the maximum number of open files in the system
59 */
60 int get_max_files(void)
61 {
62 return files_stat.max_files;
63 }
64 EXPORT_SYMBOL_GPL(get_max_files);
66 /*
67 * Handle nr_files sysctl
68 */
69 #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
70 int proc_nr_files(ctl_table *table, int write, struct file *filp,
71 void __user *buffer, size_t *lenp, loff_t *ppos)
72 {
73 files_stat.nr_files = get_nr_files();
74 return proc_dointvec(table, write, filp, buffer, lenp, ppos);
75 }
76 #else
77 int proc_nr_files(ctl_table *table, int write, struct file *filp,
78 void __user *buffer, size_t *lenp, loff_t *ppos)
79 {
80 return -ENOSYS;
81 }
82 #endif
84 /* Find an unused file structure and return a pointer to it.
85 * Returns NULL, if there are no more free file structures or
86 * we run out of memory.
87 */
88 struct file *get_empty_filp(void)
89 {
90 struct task_struct *tsk;
91 static int old_max;
92 struct file * f;
94 /*
95 * Privileged users can go above max_files
96 */
97 if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
98 /*
99 * percpu_counters are inaccurate. Do an expensive check before
100 * we go and fail.
101 */
102 if (percpu_counter_sum(&nr_files) >= files_stat.max_files)
103 goto over;
104 }
106 f = kmem_cache_alloc(filp_cachep, GFP_KERNEL);
107 if (f == NULL)
108 goto fail;
110 percpu_counter_inc(&nr_files);
111 memset(f, 0, sizeof(*f));
112 if (security_file_alloc(f))
113 goto fail_sec;
115 tsk = current;
116 INIT_LIST_HEAD(&f->f_u.fu_list);
117 atomic_set(&f->f_count, 1);
118 rwlock_init(&f->f_owner.lock);
119 f->f_uid = tsk->fsuid;
120 f->f_gid = tsk->fsgid;
121 eventpoll_init_file(f);
122 /* f->f_version: 0 */
123 return f;
125 over:
126 /* Ran out of filps - report that */
127 if (get_nr_files() > old_max) {
128 printk(KERN_INFO "VFS: file-max limit %d reached\n",
129 get_max_files());
130 old_max = get_nr_files();
131 }
132 goto fail;
134 fail_sec:
135 file_free(f);
136 fail:
137 return NULL;
138 }
140 EXPORT_SYMBOL(get_empty_filp);
142 void fastcall fput(struct file *file)
143 {
144 if (atomic_dec_and_test(&file->f_count))
145 __fput(file);
146 }
148 EXPORT_SYMBOL(fput);
150 /* __fput is called from task context when aio completion releases the last
151 * last use of a struct file *. Do not use otherwise.
152 */
153 void fastcall __fput(struct file *file)
154 {
155 struct dentry *dentry = file->f_dentry;
156 struct vfsmount *mnt = file->f_vfsmnt;
157 struct inode *inode = dentry->d_inode;
159 might_sleep();
161 fsnotify_close(file);
162 /*
163 * The function eventpoll_release() should be the first called
164 * in the file cleanup chain.
165 */
166 eventpoll_release(file);
167 locks_remove_flock(file);
169 if (file->f_op && file->f_op->release)
170 file->f_op->release(inode, file);
171 security_file_free(file);
172 if (unlikely(inode->i_cdev != NULL))
173 cdev_put(inode->i_cdev);
174 fops_put(file->f_op);
175 if (file->f_mode & FMODE_WRITE)
176 put_write_access(inode);
177 file_kill(file);
178 file->f_dentry = NULL;
179 file->f_vfsmnt = NULL;
180 file_free(file);
181 dput(dentry);
182 mntput(mnt);
183 }
185 struct file fastcall *fget(unsigned int fd)
186 {
187 struct file *file;
188 struct files_struct *files = current->files;
190 rcu_read_lock();
191 file = fcheck_files(files, fd);
192 if (file) {
193 if (!atomic_inc_not_zero(&file->f_count)) {
194 /* File object ref couldn't be taken */
195 rcu_read_unlock();
196 return NULL;
197 }
198 }
199 rcu_read_unlock();
201 return file;
202 }
204 EXPORT_SYMBOL(fget);
206 /*
207 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
208 * You can use this only if it is guranteed that the current task already
209 * holds a refcnt to that file. That check has to be done at fget() only
210 * and a flag is returned to be passed to the corresponding fput_light().
211 * There must not be a cloning between an fget_light/fput_light pair.
212 */
213 struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
214 {
215 struct file *file;
216 struct files_struct *files = current->files;
218 *fput_needed = 0;
219 if (likely((atomic_read(&files->count) == 1))) {
220 file = fcheck_files(files, fd);
221 } else {
222 rcu_read_lock();
223 file = fcheck_files(files, fd);
224 if (file) {
225 if (atomic_inc_not_zero(&file->f_count))
226 *fput_needed = 1;
227 else
228 /* Didn't get the reference, someone's freed */
229 file = NULL;
230 }
231 rcu_read_unlock();
232 }
234 return file;
235 }
238 void put_filp(struct file *file)
239 {
240 if (atomic_dec_and_test(&file->f_count)) {
241 security_file_free(file);
242 file_kill(file);
243 file_free(file);
244 }
245 }
247 void file_move(struct file *file, struct list_head *list)
248 {
249 if (!list)
250 return;
251 file_list_lock();
252 list_move(&file->f_u.fu_list, list);
253 file_list_unlock();
254 }
256 void file_kill(struct file *file)
257 {
258 if (!list_empty(&file->f_u.fu_list)) {
259 file_list_lock();
260 list_del_init(&file->f_u.fu_list);
261 file_list_unlock();
262 }
263 }
265 int fs_may_remount_ro(struct super_block *sb)
266 {
267 struct list_head *p;
269 /* Check that no files are currently opened for writing. */
270 file_list_lock();
271 list_for_each(p, &sb->s_files) {
272 struct file *file = list_entry(p, struct file, f_u.fu_list);
273 struct inode *inode = file->f_dentry->d_inode;
275 /* File with pending delete? */
276 if (inode->i_nlink == 0)
277 goto too_bad;
279 /* Writeable file? */
280 if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
281 goto too_bad;
282 }
283 file_list_unlock();
284 return 1; /* Tis' cool bro. */
285 too_bad:
286 file_list_unlock();
287 return 0;
288 }
290 void __init files_init(unsigned long mempages)
291 {
292 int n;
293 /* One file with associated inode and dcache is very roughly 1K.
294 * Per default don't use more than 10% of our memory for files.
295 */
297 n = (mempages * (PAGE_SIZE / 1024)) / 10;
298 files_stat.max_files = n;
299 if (files_stat.max_files < NR_FILE)
300 files_stat.max_files = NR_FILE;
301 files_defer_init();
302 percpu_counter_init(&nr_files, 0);
303 }