blob: 835d25e335095985fd7a4409c26ae9b5198fb571 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * fs/libfs.c
3 * Library for filesystems writers.
4 */
5
Fabian Frederickac13a822014-06-04 16:06:27 -07006#include <linux/blkdev.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -05007#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008#include <linux/pagemap.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +09009#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/mount.h>
11#include <linux/vfs.h>
npiggin@suse.de7bb46a62010-05-27 01:05:33 +100012#include <linux/quotaops.h>
Ingo Molnar7cf34c72006-03-23 03:00:36 -080013#include <linux/mutex.h>
Al Viro87dc8002013-09-16 10:30:04 -040014#include <linux/namei.h>
Christoph Hellwig25961102007-10-21 16:42:05 -070015#include <linux/exportfs.h>
Al Virod5aacad2009-06-07 14:56:44 -040016#include <linux/writeback.h>
Al Viroff01bb482011-09-16 02:31:11 -040017#include <linux/buffer_head.h> /* sync_mapping_buffers */
Ingo Molnar7cf34c72006-03-23 03:00:36 -080018
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <asm/uaccess.h>
20
Al Viroa4464db2011-07-07 15:03:58 -040021#include "internal.h"
22
Linus Torvalds1da177e2005-04-16 15:20:36 -070023int simple_getattr(struct vfsmount *mnt, struct dentry *dentry,
24 struct kstat *stat)
25{
David Howellsdea655c2015-03-17 22:26:15 +000026 struct inode *inode = d_inode(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -070027 generic_fillattr(inode, stat);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +030028 stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
Linus Torvalds1da177e2005-04-16 15:20:36 -070029 return 0;
30}
Al Viro12f38872013-09-15 21:20:49 -040031EXPORT_SYMBOL(simple_getattr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
David Howells726c3342006-06-23 02:02:58 -070033int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -070034{
David Howells726c3342006-06-23 02:02:58 -070035 buf->f_type = dentry->d_sb->s_magic;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +030036 buf->f_bsize = PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 buf->f_namelen = NAME_MAX;
38 return 0;
39}
Al Viro12f38872013-09-15 21:20:49 -040040EXPORT_SYMBOL(simple_statfs);
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
42/*
43 * Retaining negative dentries for an in-memory filesystem just wastes
44 * memory and lookup time: arrange for them to be deleted immediately.
45 */
Al Virob26d4cd2013-10-25 18:47:37 -040046int always_delete_dentry(const struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -070047{
48 return 1;
49}
Al Virob26d4cd2013-10-25 18:47:37 -040050EXPORT_SYMBOL(always_delete_dentry);
51
52const struct dentry_operations simple_dentry_operations = {
53 .d_delete = always_delete_dentry,
54};
55EXPORT_SYMBOL(simple_dentry_operations);
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
57/*
58 * Lookup the data. This is trivial - if the dentry didn't already
59 * exist, we know it is negative. Set d_op to delete negative dentries.
60 */
Al Viro00cd8dd2012-06-10 17:13:09 -040061struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -070062{
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 if (dentry->d_name.len > NAME_MAX)
64 return ERR_PTR(-ENAMETOOLONG);
Al Viro74931da2013-07-14 17:43:25 +040065 if (!dentry->d_sb->s_d_op)
66 d_set_d_op(dentry, &simple_dentry_operations);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 d_add(dentry, NULL);
68 return NULL;
69}
Al Viro12f38872013-09-15 21:20:49 -040070EXPORT_SYMBOL(simple_lookup);
Linus Torvalds1da177e2005-04-16 15:20:36 -070071
Linus Torvalds1da177e2005-04-16 15:20:36 -070072int dcache_dir_open(struct inode *inode, struct file *file)
73{
Al Viroba65dc52016-06-10 11:32:47 -040074 file->private_data = d_alloc_cursor(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
76 return file->private_data ? 0 : -ENOMEM;
77}
Al Viro12f38872013-09-15 21:20:49 -040078EXPORT_SYMBOL(dcache_dir_open);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
80int dcache_dir_close(struct inode *inode, struct file *file)
81{
82 dput(file->private_data);
83 return 0;
84}
Al Viro12f38872013-09-15 21:20:49 -040085EXPORT_SYMBOL(dcache_dir_close);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
Al Viro4f42c1b2016-06-06 19:37:13 -040087/* parent is locked at least shared */
Al Virob3498842019-09-15 12:12:39 -040088/*
89 * Returns an element of siblings' list.
90 * We are looking for <count>th positive after <p>; if
91 * found, dentry is grabbed and passed to caller via *<res>.
92 * If no such element exists, the anchor of list is returned
93 * and *<res> is set to NULL.
94 */
95static struct list_head *scan_positives(struct dentry *cursor,
96 struct list_head *p,
97 loff_t count,
98 struct dentry **res)
Al Viro4f42c1b2016-06-06 19:37:13 -040099{
Al Virob3498842019-09-15 12:12:39 -0400100 struct dentry *dentry = cursor->d_parent, *found = NULL;
Al Viro4f42c1b2016-06-06 19:37:13 -0400101
Al Virob3498842019-09-15 12:12:39 -0400102 spin_lock(&dentry->d_lock);
103 while ((p = p->next) != &dentry->d_subdirs) {
Al Viro4f42c1b2016-06-06 19:37:13 -0400104 struct dentry *d = list_entry(p, struct dentry, d_child);
Al Virob3498842019-09-15 12:12:39 -0400105 // we must at least skip cursors, to avoid livelocks
106 if (d->d_flags & DCACHE_DENTRY_CURSOR)
107 continue;
108 if (simple_positive(d) && !--count) {
109 spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
110 if (simple_positive(d))
111 found = dget_dlock(d);
112 spin_unlock(&d->d_lock);
113 if (likely(found))
114 break;
115 count = 1;
116 }
117 if (need_resched()) {
118 list_move(&cursor->d_child, p);
119 p = &cursor->d_child;
120 spin_unlock(&dentry->d_lock);
121 cond_resched();
122 spin_lock(&dentry->d_lock);
Al Viro4f42c1b2016-06-06 19:37:13 -0400123 }
124 }
Al Virob3498842019-09-15 12:12:39 -0400125 spin_unlock(&dentry->d_lock);
126 dput(*res);
127 *res = found;
128 return p;
Al Viro4f42c1b2016-06-06 19:37:13 -0400129}
130
Andrew Morton965c8e52012-12-17 15:59:39 -0800131loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132{
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100133 struct dentry *dentry = file->f_path.dentry;
Andrew Morton965c8e52012-12-17 15:59:39 -0800134 switch (whence) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 case 1:
136 offset += file->f_pos;
137 case 0:
138 if (offset >= 0)
139 break;
140 default:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 return -EINVAL;
142 }
143 if (offset != file->f_pos) {
Al Virob3498842019-09-15 12:12:39 -0400144 struct dentry *cursor = file->private_data;
145 struct dentry *to = NULL;
146 struct list_head *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147
Al Virob3498842019-09-15 12:12:39 -0400148 file->f_pos = offset;
149 inode_lock_shared(dentry->d_inode);
150
151 if (file->f_pos > 2) {
152 p = scan_positives(cursor, &dentry->d_subdirs,
153 file->f_pos - 2, &to);
154 spin_lock(&dentry->d_lock);
155 list_move(&cursor->d_child, p);
156 spin_unlock(&dentry->d_lock);
157 } else {
158 spin_lock(&dentry->d_lock);
159 list_del_init(&cursor->d_child);
160 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 }
Al Virob3498842019-09-15 12:12:39 -0400162
163 dput(to);
164
165 inode_unlock_shared(dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 return offset;
168}
Al Viro12f38872013-09-15 21:20:49 -0400169EXPORT_SYMBOL(dcache_dir_lseek);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
171/* Relationship between i_mode and the DT_xxx types */
172static inline unsigned char dt_type(struct inode *inode)
173{
174 return (inode->i_mode >> 12) & 15;
175}
176
177/*
178 * Directory is locked and all positive dentries in it are safe, since
179 * for ramfs-type trees they can't go away without unlink() or rmdir(),
180 * both impossible due to the lock on directory.
181 */
182
Al Viro5f99f4e2013-05-15 20:23:06 -0400183int dcache_readdir(struct file *file, struct dir_context *ctx)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184{
Al Viro5f99f4e2013-05-15 20:23:06 -0400185 struct dentry *dentry = file->f_path.dentry;
186 struct dentry *cursor = file->private_data;
Al Virob3498842019-09-15 12:12:39 -0400187 struct list_head *anchor = &dentry->d_subdirs;
188 struct dentry *next = NULL;
189 struct list_head *p;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190
Al Viro5f99f4e2013-05-15 20:23:06 -0400191 if (!dir_emit_dots(file, ctx))
192 return 0;
Al Viro4f42c1b2016-06-06 19:37:13 -0400193
Al Viro5f99f4e2013-05-15 20:23:06 -0400194 if (ctx->pos == 2)
Al Virob3498842019-09-15 12:12:39 -0400195 p = anchor;
196 else
197 p = &cursor->d_child;
198
199 while ((p = scan_positives(cursor, p, 1, &next)) != anchor) {
Al Viro5f99f4e2013-05-15 20:23:06 -0400200 if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
David Howellsdea655c2015-03-17 22:26:15 +0000201 d_inode(next)->i_ino, dt_type(d_inode(next))))
Al Viro4f42c1b2016-06-06 19:37:13 -0400202 break;
Al Viro5f99f4e2013-05-15 20:23:06 -0400203 ctx->pos++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 }
Al Virob3498842019-09-15 12:12:39 -0400205 spin_lock(&dentry->d_lock);
206 list_move_tail(&cursor->d_child, p);
207 spin_unlock(&dentry->d_lock);
208 dput(next);
209
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 return 0;
211}
Al Viro12f38872013-09-15 21:20:49 -0400212EXPORT_SYMBOL(dcache_readdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213
214ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
215{
216 return -EISDIR;
217}
Al Viro12f38872013-09-15 21:20:49 -0400218EXPORT_SYMBOL(generic_read_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800220const struct file_operations simple_dir_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 .open = dcache_dir_open,
222 .release = dcache_dir_close,
223 .llseek = dcache_dir_lseek,
224 .read = generic_read_dir,
Al Viro4e829012016-04-20 19:52:15 -0400225 .iterate_shared = dcache_readdir,
Christoph Hellwig1b061d92010-05-26 17:53:41 +0200226 .fsync = noop_fsync,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227};
Al Viro12f38872013-09-15 21:20:49 -0400228EXPORT_SYMBOL(simple_dir_operations);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800230const struct inode_operations simple_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 .lookup = simple_lookup,
232};
Al Viro12f38872013-09-15 21:20:49 -0400233EXPORT_SYMBOL(simple_dir_inode_operations);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
Hugh Dickins759b9772007-03-05 00:30:28 -0800235static const struct super_operations simple_super_operations = {
236 .statfs = simple_statfs,
237};
238
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239/*
240 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
241 * will never be mountable)
242 */
Andreas Gruenbacherbba0bd32016-09-29 17:48:35 +0200243struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name,
244 const struct super_operations *ops, const struct xattr_handler **xattr,
Al Viroc74a1cb2011-01-12 16:59:34 -0500245 const struct dentry_operations *dops, unsigned long magic)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246{
David Howells9249e172012-06-25 12:55:37 +0100247 struct super_block *s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 struct dentry *dentry;
249 struct inode *root;
Linus Torvalds26fe5752012-05-10 13:14:12 -0700250 struct qstr d_name = QSTR_INIT(name, strlen(name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251
Eric W. Biedermanc4081f92017-01-04 17:37:27 +1300252 s = sget_userns(fs_type, NULL, set_anon_super, MS_KERNMOUNT|MS_NOUSER,
253 &init_user_ns, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 if (IS_ERR(s))
Al Viro51139ad2010-07-25 23:47:46 +0400255 return ERR_CAST(s);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
Jeff Layton89a4eb42009-08-18 14:11:08 -0700257 s->s_maxbytes = MAX_LFS_FILESIZE;
Alex Nixon3971e1a2008-07-29 22:33:03 -0700258 s->s_blocksize = PAGE_SIZE;
259 s->s_blocksize_bits = PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800261 s->s_op = ops ? ops : &simple_super_operations;
Andreas Gruenbacherbba0bd32016-09-29 17:48:35 +0200262 s->s_xattr = xattr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 s->s_time_gran = 1;
264 root = new_inode(s);
265 if (!root)
266 goto Enomem;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700267 /*
268 * since this is the first inode, make it number 1. New inodes created
269 * after this must take care not to collide with it (by passing
270 * max_reserved of 1 to iunique).
271 */
272 root->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
Deepa Dinamani078cd822016-09-14 07:48:04 -0700274 root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
Al Viroa4464db2011-07-07 15:03:58 -0400275 dentry = __d_alloc(s, &d_name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 if (!dentry) {
277 iput(root);
278 goto Enomem;
279 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 d_instantiate(dentry, root);
281 s->s_root = dentry;
Al Viroc74a1cb2011-01-12 16:59:34 -0500282 s->s_d_op = dops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 s->s_flags |= MS_ACTIVE;
Al Viro51139ad2010-07-25 23:47:46 +0400284 return dget(s->s_root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
286Enomem:
Al Viro6f5bbff2009-05-06 01:34:22 -0400287 deactivate_locked_super(s);
Al Viro51139ad2010-07-25 23:47:46 +0400288 return ERR_PTR(-ENOMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289}
Andreas Gruenbacherbba0bd32016-09-29 17:48:35 +0200290EXPORT_SYMBOL(mount_pseudo_xattr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
Stephen Boyd20955e82012-04-05 14:25:09 -0700292int simple_open(struct inode *inode, struct file *file)
293{
294 if (inode->i_private)
295 file->private_data = inode->i_private;
296 return 0;
297}
Al Viro12f38872013-09-15 21:20:49 -0400298EXPORT_SYMBOL(simple_open);
Stephen Boyd20955e82012-04-05 14:25:09 -0700299
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
301{
David Howellsdea655c2015-03-17 22:26:15 +0000302 struct inode *inode = d_inode(old_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303
Deepa Dinamani078cd822016-09-14 07:48:04 -0700304 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
Dave Hansend8c76e62006-09-30 23:29:04 -0700305 inc_nlink(inode);
Al Viro7de9c6ee2010-10-23 11:11:40 -0400306 ihold(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 dget(dentry);
308 d_instantiate(dentry, inode);
309 return 0;
310}
Al Viro12f38872013-09-15 21:20:49 -0400311EXPORT_SYMBOL(simple_link);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313int simple_empty(struct dentry *dentry)
314{
315 struct dentry *child;
316 int ret = 0;
317
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100318 spin_lock(&dentry->d_lock);
Al Viro946e51f2014-10-26 19:19:16 -0400319 list_for_each_entry(child, &dentry->d_subdirs, d_child) {
Nick Pigginda502952011-01-07 17:49:33 +1100320 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
321 if (simple_positive(child)) {
322 spin_unlock(&child->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 goto out;
Nick Pigginda502952011-01-07 17:49:33 +1100324 }
325 spin_unlock(&child->d_lock);
326 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 ret = 1;
328out:
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100329 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 return ret;
331}
Al Viro12f38872013-09-15 21:20:49 -0400332EXPORT_SYMBOL(simple_empty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333
334int simple_unlink(struct inode *dir, struct dentry *dentry)
335{
David Howellsdea655c2015-03-17 22:26:15 +0000336 struct inode *inode = d_inode(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
Deepa Dinamani078cd822016-09-14 07:48:04 -0700338 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700339 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 dput(dentry);
341 return 0;
342}
Al Viro12f38872013-09-15 21:20:49 -0400343EXPORT_SYMBOL(simple_unlink);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
345int simple_rmdir(struct inode *dir, struct dentry *dentry)
346{
347 if (!simple_empty(dentry))
348 return -ENOTEMPTY;
349
David Howellsdea655c2015-03-17 22:26:15 +0000350 drop_nlink(d_inode(dentry));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 simple_unlink(dir, dentry);
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700352 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 return 0;
354}
Al Viro12f38872013-09-15 21:20:49 -0400355EXPORT_SYMBOL(simple_rmdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
357int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
Miklos Szeredie0e0be82016-09-27 11:03:57 +0200358 struct inode *new_dir, struct dentry *new_dentry,
359 unsigned int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360{
David Howellsdea655c2015-03-17 22:26:15 +0000361 struct inode *inode = d_inode(old_dentry);
David Howellse36cb0b2015-01-29 12:02:35 +0000362 int they_are_dirs = d_is_dir(old_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363
Miklos Szeredie0e0be82016-09-27 11:03:57 +0200364 if (flags & ~RENAME_NOREPLACE)
365 return -EINVAL;
366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 if (!simple_empty(new_dentry))
368 return -ENOTEMPTY;
369
David Howellsdea655c2015-03-17 22:26:15 +0000370 if (d_really_is_positive(new_dentry)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 simple_unlink(new_dir, new_dentry);
Al Viro841590c2011-07-21 15:49:09 -0400372 if (they_are_dirs) {
David Howellsdea655c2015-03-17 22:26:15 +0000373 drop_nlink(d_inode(new_dentry));
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700374 drop_nlink(old_dir);
Al Viro841590c2011-07-21 15:49:09 -0400375 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -0700377 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -0700378 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 }
380
381 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
Deepa Dinamani078cd822016-09-14 07:48:04 -0700382 new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383
384 return 0;
385}
Al Viro12f38872013-09-15 21:20:49 -0400386EXPORT_SYMBOL(simple_rename);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000388/**
Christoph Hellwigeef23802010-06-04 11:30:01 +0200389 * simple_setattr - setattr for simple filesystem
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000390 * @dentry: dentry
391 * @iattr: iattr structure
392 *
393 * Returns 0 on success, -error on failure.
394 *
Christoph Hellwigeef23802010-06-04 11:30:01 +0200395 * simple_setattr is a simple ->setattr implementation without a proper
396 * implementation of size changes.
397 *
398 * It can either be used for in-memory filesystems or special files
399 * on simple regular filesystems. Anything that needs to change on-disk
400 * or wire state on size changes needs its own setattr method.
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000401 */
402int simple_setattr(struct dentry *dentry, struct iattr *iattr)
403{
David Howellsdea655c2015-03-17 22:26:15 +0000404 struct inode *inode = d_inode(dentry);
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000405 int error;
406
Jan Kara31051c82016-05-26 16:55:18 +0200407 error = setattr_prepare(dentry, iattr);
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000408 if (error)
409 return error;
410
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200411 if (iattr->ia_valid & ATTR_SIZE)
412 truncate_setsize(inode, iattr->ia_size);
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200413 setattr_copy(inode, iattr);
Christoph Hellwigeef23802010-06-04 11:30:01 +0200414 mark_inode_dirty(inode);
415 return 0;
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000416}
417EXPORT_SYMBOL(simple_setattr);
418
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419int simple_readpage(struct file *file, struct page *page)
420{
Pekka J Enbergc0d92cb2006-09-29 01:59:09 -0700421 clear_highpage(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 flush_dcache_page(page);
423 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 unlock_page(page);
425 return 0;
426}
Al Viro12f38872013-09-15 21:20:49 -0400427EXPORT_SYMBOL(simple_readpage);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428
Nick Pigginafddba42007-10-16 01:25:01 -0700429int simple_write_begin(struct file *file, struct address_space *mapping,
430 loff_t pos, unsigned len, unsigned flags,
431 struct page **pagep, void **fsdata)
432{
433 struct page *page;
434 pgoff_t index;
Nick Pigginafddba42007-10-16 01:25:01 -0700435
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300436 index = pos >> PAGE_SHIFT;
Nick Pigginafddba42007-10-16 01:25:01 -0700437
Nick Piggin54566b22009-01-04 12:00:53 -0800438 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Pigginafddba42007-10-16 01:25:01 -0700439 if (!page)
440 return -ENOMEM;
441
442 *pagep = page;
443
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300444 if (!PageUptodate(page) && (len != PAGE_SIZE)) {
445 unsigned from = pos & (PAGE_SIZE - 1);
Boaz Harrosh193cf4b2010-01-12 16:18:08 +0200446
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300447 zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
Boaz Harrosh193cf4b2010-01-12 16:18:08 +0200448 }
449 return 0;
Nick Pigginafddba42007-10-16 01:25:01 -0700450}
Al Viro12f38872013-09-15 21:20:49 -0400451EXPORT_SYMBOL(simple_write_begin);
Nick Pigginafddba42007-10-16 01:25:01 -0700452
Boaz Harroshad2a722f2010-01-12 15:13:47 +0200453/**
454 * simple_write_end - .write_end helper for non-block-device FSes
455 * @available: See .write_end of address_space_operations
456 * @file: "
457 * @mapping: "
458 * @pos: "
459 * @len: "
460 * @copied: "
461 * @page: "
462 * @fsdata: "
463 *
464 * simple_write_end does the minimum needed for updating a page after writing is
465 * done. It has the same API signature as the .write_end of
466 * address_space_operations vector. So it can just be set onto .write_end for
467 * FSes that don't need any other processing. i_mutex is assumed to be held.
468 * Block based filesystems should use generic_write_end().
469 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
470 * is not called, so a filesystem that actually does store data in .write_inode
471 * should extend on what's done here with a call to mark_inode_dirty() in the
472 * case that i_size has changed.
473 */
474int simple_write_end(struct file *file, struct address_space *mapping,
475 loff_t pos, unsigned len, unsigned copied,
476 struct page *page, void *fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477{
478 struct inode *inode = page->mapping->host;
Boaz Harroshad2a722f2010-01-12 15:13:47 +0200479 loff_t last_pos = pos + copied;
480
481 /* zero the stale part of the page if we did a short copy */
482 if (copied < len) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300483 unsigned from = pos & (PAGE_SIZE - 1);
Boaz Harroshad2a722f2010-01-12 15:13:47 +0200484
485 zero_user(page, from + copied, len - copied);
486 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487
Nick Piggin955eff52007-02-20 13:58:08 -0800488 if (!PageUptodate(page))
489 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 /*
491 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800492 * cannot change under us because we hold the i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 */
Boaz Harroshad2a722f2010-01-12 15:13:47 +0200494 if (last_pos > inode->i_size)
495 i_size_write(inode, last_pos);
496
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 set_page_dirty(page);
Nick Pigginafddba42007-10-16 01:25:01 -0700498 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300499 put_page(page);
Nick Pigginafddba42007-10-16 01:25:01 -0700500
501 return copied;
502}
Al Viro12f38872013-09-15 21:20:49 -0400503EXPORT_SYMBOL(simple_write_end);
Nick Pigginafddba42007-10-16 01:25:01 -0700504
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700505/*
506 * the inodes created here are not hashed. If you use iunique to generate
507 * unique inode values later for this filesystem, then you must take care
508 * to pass it an appropriate max_reserved value to avoid collisions.
509 */
Roberto Sassu7d683a02010-06-03 11:58:28 +0200510int simple_fill_super(struct super_block *s, unsigned long magic,
511 struct tree_descr *files)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 struct inode *inode;
514 struct dentry *root;
515 struct dentry *dentry;
516 int i;
517
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300518 s->s_blocksize = PAGE_SIZE;
519 s->s_blocksize_bits = PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520 s->s_magic = magic;
Hugh Dickins759b9772007-03-05 00:30:28 -0800521 s->s_op = &simple_super_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 s->s_time_gran = 1;
523
524 inode = new_inode(s);
525 if (!inode)
526 return -ENOMEM;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700527 /*
528 * because the root inode is 1, the files array must not contain an
529 * entry at index 1
530 */
531 inode->i_ino = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 inode->i_mode = S_IFDIR | 0755;
Deepa Dinamani078cd822016-09-14 07:48:04 -0700533 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 inode->i_op = &simple_dir_inode_operations;
535 inode->i_fop = &simple_dir_operations;
Miklos Szeredibfe86842011-10-28 14:13:29 +0200536 set_nlink(inode, 2);
Al Viro48fde702012-01-08 22:15:13 -0500537 root = d_make_root(inode);
538 if (!root)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 for (i = 0; !files->name || files->name[0]; i++, files++) {
541 if (!files->name)
542 continue;
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700543
544 /* warn if it tries to conflict with the root inode */
545 if (unlikely(i == 1))
546 printk(KERN_WARNING "%s: %s passed in a files array"
547 "with an index of 1!\n", __func__,
548 s->s_type->name);
549
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550 dentry = d_alloc_name(root, files->name);
551 if (!dentry)
552 goto out;
553 inode = new_inode(s);
Konstantin Khlebnikov32096ea2011-11-01 16:12:33 +0300554 if (!inode) {
555 dput(dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 goto out;
Konstantin Khlebnikov32096ea2011-11-01 16:12:33 +0300557 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 inode->i_mode = S_IFREG | files->mode;
Deepa Dinamani078cd822016-09-14 07:48:04 -0700559 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 inode->i_fop = files->ops;
561 inode->i_ino = i;
562 d_add(dentry, inode);
563 }
564 s->s_root = root;
565 return 0;
566out:
567 d_genocide(root);
Al Viro640946f2012-04-02 19:22:25 -0400568 shrink_dcache_parent(root);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 dput(root);
570 return -ENOMEM;
571}
Al Viro12f38872013-09-15 21:20:49 -0400572EXPORT_SYMBOL(simple_fill_super);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573
574static DEFINE_SPINLOCK(pin_fs_lock);
575
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400576int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577{
578 struct vfsmount *mnt = NULL;
579 spin_lock(&pin_fs_lock);
580 if (unlikely(!*mount)) {
581 spin_unlock(&pin_fs_lock);
Al Viro24529922012-03-17 02:13:52 -0400582 mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583 if (IS_ERR(mnt))
584 return PTR_ERR(mnt);
585 spin_lock(&pin_fs_lock);
586 if (!*mount)
587 *mount = mnt;
588 }
589 mntget(*mount);
590 ++*count;
591 spin_unlock(&pin_fs_lock);
592 mntput(mnt);
593 return 0;
594}
Al Viro12f38872013-09-15 21:20:49 -0400595EXPORT_SYMBOL(simple_pin_fs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596
597void simple_release_fs(struct vfsmount **mount, int *count)
598{
599 struct vfsmount *mnt;
600 spin_lock(&pin_fs_lock);
601 mnt = *mount;
602 if (!--*count)
603 *mount = NULL;
604 spin_unlock(&pin_fs_lock);
605 mntput(mnt);
606}
Al Viro12f38872013-09-15 21:20:49 -0400607EXPORT_SYMBOL(simple_release_fs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700609/**
610 * simple_read_from_buffer - copy data from the buffer to user space
611 * @to: the user space buffer to read to
612 * @count: the maximum number of bytes to read
613 * @ppos: the current position in the buffer
614 * @from: the buffer to read from
615 * @available: the size of the buffer
616 *
617 * The simple_read_from_buffer() function reads up to @count bytes from the
618 * buffer @from at offset @ppos into the user space address starting at @to.
619 *
620 * On success, the number of bytes read is returned and the offset @ppos is
621 * advanced by this number, or negative value is returned on error.
622 **/
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
624 const void *from, size_t available)
625{
626 loff_t pos = *ppos;
Steven Rostedt14be2742009-09-18 13:05:42 -0700627 size_t ret;
628
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 if (pos < 0)
630 return -EINVAL;
Steven Rostedt14be2742009-09-18 13:05:42 -0700631 if (pos >= available || !count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 return 0;
633 if (count > available - pos)
634 count = available - pos;
Steven Rostedt14be2742009-09-18 13:05:42 -0700635 ret = copy_to_user(to, from + pos, count);
636 if (ret == count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 return -EFAULT;
Steven Rostedt14be2742009-09-18 13:05:42 -0700638 count -= ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 *ppos = pos + count;
640 return count;
641}
Al Viro12f38872013-09-15 21:20:49 -0400642EXPORT_SYMBOL(simple_read_from_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700644/**
Jiri Slaby6a727b42010-05-01 23:51:22 +0200645 * simple_write_to_buffer - copy data from user space to the buffer
646 * @to: the buffer to write to
647 * @available: the size of the buffer
648 * @ppos: the current position in the buffer
649 * @from: the user space buffer to read from
650 * @count: the maximum number of bytes to read
651 *
652 * The simple_write_to_buffer() function reads up to @count bytes from the user
653 * space address starting at @from into the buffer @to at offset @ppos.
654 *
655 * On success, the number of bytes written is returned and the offset @ppos is
656 * advanced by this number, or negative value is returned on error.
657 **/
658ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
659 const void __user *from, size_t count)
660{
661 loff_t pos = *ppos;
662 size_t res;
663
664 if (pos < 0)
665 return -EINVAL;
666 if (pos >= available || !count)
667 return 0;
668 if (count > available - pos)
669 count = available - pos;
670 res = copy_from_user(to + pos, from, count);
671 if (res == count)
672 return -EFAULT;
673 count -= res;
674 *ppos = pos + count;
675 return count;
676}
Al Viro12f38872013-09-15 21:20:49 -0400677EXPORT_SYMBOL(simple_write_to_buffer);
Jiri Slaby6a727b42010-05-01 23:51:22 +0200678
679/**
Akinobu Mita6d1029b2008-07-04 09:59:51 -0700680 * memory_read_from_buffer - copy data from the buffer
681 * @to: the kernel space buffer to read to
682 * @count: the maximum number of bytes to read
683 * @ppos: the current position in the buffer
684 * @from: the buffer to read from
685 * @available: the size of the buffer
686 *
687 * The memory_read_from_buffer() function reads up to @count bytes from the
688 * buffer @from at offset @ppos into the kernel space address starting at @to.
689 *
690 * On success, the number of bytes read is returned and the offset @ppos is
691 * advanced by this number, or negative value is returned on error.
692 **/
Akinobu Mita93b07112008-06-05 22:46:21 -0700693ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
694 const void *from, size_t available)
695{
696 loff_t pos = *ppos;
697
698 if (pos < 0)
699 return -EINVAL;
700 if (pos >= available)
701 return 0;
702 if (count > available - pos)
703 count = available - pos;
704 memcpy(to, from + pos, count);
705 *ppos = pos + count;
706
707 return count;
708}
Al Viro12f38872013-09-15 21:20:49 -0400709EXPORT_SYMBOL(memory_read_from_buffer);
Akinobu Mita93b07112008-06-05 22:46:21 -0700710
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711/*
712 * Transaction based IO.
713 * The file expects a single write which triggers the transaction, and then
714 * possibly a read which collects the result - which is stored in a
715 * file-local buffer.
716 */
Ingo Molnar76791ab2009-03-25 16:48:35 +0100717
718void simple_transaction_set(struct file *file, size_t n)
719{
720 struct simple_transaction_argresp *ar = file->private_data;
721
722 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
723
724 /*
725 * The barrier ensures that ar->size will really remain zero until
726 * ar->data is ready for reading.
727 */
728 smp_mb();
729 ar->size = n;
730}
Al Viro12f38872013-09-15 21:20:49 -0400731EXPORT_SYMBOL(simple_transaction_set);
Ingo Molnar76791ab2009-03-25 16:48:35 +0100732
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
734{
735 struct simple_transaction_argresp *ar;
736 static DEFINE_SPINLOCK(simple_transaction_lock);
737
738 if (size > SIMPLE_TRANSACTION_LIMIT - 1)
739 return ERR_PTR(-EFBIG);
740
741 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
742 if (!ar)
743 return ERR_PTR(-ENOMEM);
744
745 spin_lock(&simple_transaction_lock);
746
747 /* only one write allowed per open */
748 if (file->private_data) {
749 spin_unlock(&simple_transaction_lock);
750 free_page((unsigned long)ar);
751 return ERR_PTR(-EBUSY);
752 }
753
754 file->private_data = ar;
755
756 spin_unlock(&simple_transaction_lock);
757
758 if (copy_from_user(ar->data, buf, size))
759 return ERR_PTR(-EFAULT);
760
761 return ar->data;
762}
Al Viro12f38872013-09-15 21:20:49 -0400763EXPORT_SYMBOL(simple_transaction_get);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764
765ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
766{
767 struct simple_transaction_argresp *ar = file->private_data;
768
769 if (!ar)
770 return 0;
771 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
772}
Al Viro12f38872013-09-15 21:20:49 -0400773EXPORT_SYMBOL(simple_transaction_read);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
775int simple_transaction_release(struct inode *inode, struct file *file)
776{
777 free_page((unsigned long)file->private_data);
778 return 0;
779}
Al Viro12f38872013-09-15 21:20:49 -0400780EXPORT_SYMBOL(simple_transaction_release);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200782/* Simple attribute files */
783
784struct simple_attr {
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800785 int (*get)(void *, u64 *);
786 int (*set)(void *, u64);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200787 char get_buf[24]; /* enough to store a u64 and "\n\0" */
788 char set_buf[24];
789 void *data;
790 const char *fmt; /* format for read operation */
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800791 struct mutex mutex; /* protects access to these buffers */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200792};
793
794/* simple_attr_open is called by an actual attribute open file operation
795 * to set the attribute specific access operations. */
796int simple_attr_open(struct inode *inode, struct file *file,
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800797 int (*get)(void *, u64 *), int (*set)(void *, u64),
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200798 const char *fmt)
799{
800 struct simple_attr *attr;
801
Eric Biggers696119f2020-03-07 18:38:49 -0800802 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200803 if (!attr)
804 return -ENOMEM;
805
806 attr->get = get;
807 attr->set = set;
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700808 attr->data = inode->i_private;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200809 attr->fmt = fmt;
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800810 mutex_init(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200811
812 file->private_data = attr;
813
814 return nonseekable_open(inode, file);
815}
Al Viro12f38872013-09-15 21:20:49 -0400816EXPORT_SYMBOL_GPL(simple_attr_open);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200817
Christoph Hellwig74bedc42008-02-08 04:20:28 -0800818int simple_attr_release(struct inode *inode, struct file *file)
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200819{
820 kfree(file->private_data);
821 return 0;
822}
Al Viro12f38872013-09-15 21:20:49 -0400823EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200824
825/* read from the buffer that is filled with the get function */
826ssize_t simple_attr_read(struct file *file, char __user *buf,
827 size_t len, loff_t *ppos)
828{
829 struct simple_attr *attr;
830 size_t size;
831 ssize_t ret;
832
833 attr = file->private_data;
834
835 if (!attr->get)
836 return -EACCES;
837
Christoph Hellwig92613032008-02-08 04:20:27 -0800838 ret = mutex_lock_interruptible(&attr->mutex);
839 if (ret)
840 return ret;
841
Eric Biggers696119f2020-03-07 18:38:49 -0800842 if (*ppos && attr->get_buf[0]) {
843 /* continued read */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200844 size = strlen(attr->get_buf);
Eric Biggers696119f2020-03-07 18:38:49 -0800845 } else {
846 /* first read */
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800847 u64 val;
848 ret = attr->get(attr->data, &val);
849 if (ret)
850 goto out;
851
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200852 size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800853 attr->fmt, (unsigned long long)val);
854 }
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200855
856 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
Christoph Hellwig8b88b092008-02-08 04:20:26 -0800857out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800858 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200859 return ret;
860}
Al Viro12f38872013-09-15 21:20:49 -0400861EXPORT_SYMBOL_GPL(simple_attr_read);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200862
863/* interpret the buffer as a number to call the set function with */
864ssize_t simple_attr_write(struct file *file, const char __user *buf,
865 size_t len, loff_t *ppos)
866{
867 struct simple_attr *attr;
Yicong Yang8dd5f582020-11-21 22:17:19 -0800868 unsigned long long val;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200869 size_t size;
870 ssize_t ret;
871
872 attr = file->private_data;
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200873 if (!attr->set)
874 return -EACCES;
875
Christoph Hellwig92613032008-02-08 04:20:27 -0800876 ret = mutex_lock_interruptible(&attr->mutex);
877 if (ret)
878 return ret;
879
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200880 ret = -EFAULT;
881 size = min(sizeof(attr->set_buf) - 1, len);
882 if (copy_from_user(attr->set_buf, buf, size))
883 goto out;
884
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200885 attr->set_buf[size] = '\0';
Yicong Yang8dd5f582020-11-21 22:17:19 -0800886 ret = kstrtoull(attr->set_buf, 0, &val);
887 if (ret)
888 goto out;
Wu Fengguang05cc0ce2009-09-18 13:06:03 -0700889 ret = attr->set(attr->data, val);
890 if (ret == 0)
891 ret = len; /* on success, claim we got the whole input */
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200892out:
Ingo Molnar7cf34c72006-03-23 03:00:36 -0800893 mutex_unlock(&attr->mutex);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200894 return ret;
895}
Al Viro12f38872013-09-15 21:20:49 -0400896EXPORT_SYMBOL_GPL(simple_attr_write);
Arnd Bergmannacaefc22005-05-18 14:40:59 +0200897
Christoph Hellwig25961102007-10-21 16:42:05 -0700898/**
899 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
900 * @sb: filesystem to do the file handle conversion on
901 * @fid: file handle to convert
902 * @fh_len: length of the file handle in bytes
903 * @fh_type: type of file handle
904 * @get_inode: filesystem callback to retrieve inode
905 *
906 * This function decodes @fid as long as it has one of the well-known
907 * Linux filehandle types and calls @get_inode on it to retrieve the
908 * inode for the object specified in the file handle.
909 */
910struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
911 int fh_len, int fh_type, struct inode *(*get_inode)
912 (struct super_block *sb, u64 ino, u32 gen))
913{
914 struct inode *inode = NULL;
915
916 if (fh_len < 2)
917 return NULL;
918
919 switch (fh_type) {
920 case FILEID_INO32_GEN:
921 case FILEID_INO32_GEN_PARENT:
922 inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
923 break;
924 }
925
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200926 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700927}
928EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
929
930/**
Yanchuan Nianca186832012-09-05 16:31:29 +0800931 * generic_fh_to_parent - generic helper for the fh_to_parent export operation
Christoph Hellwig25961102007-10-21 16:42:05 -0700932 * @sb: filesystem to do the file handle conversion on
933 * @fid: file handle to convert
934 * @fh_len: length of the file handle in bytes
935 * @fh_type: type of file handle
936 * @get_inode: filesystem callback to retrieve inode
937 *
938 * This function decodes @fid as long as it has one of the well-known
939 * Linux filehandle types and calls @get_inode on it to retrieve the
940 * inode for the _parent_ object specified in the file handle if it
941 * is specified in the file handle, or NULL otherwise.
942 */
943struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
944 int fh_len, int fh_type, struct inode *(*get_inode)
945 (struct super_block *sb, u64 ino, u32 gen))
946{
947 struct inode *inode = NULL;
948
949 if (fh_len <= 2)
950 return NULL;
951
952 switch (fh_type) {
953 case FILEID_INO32_GEN_PARENT:
954 inode = get_inode(sb, fid->i32.parent_ino,
955 (fh_len > 3 ? fid->i32.parent_gen : 0));
956 break;
957 }
958
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200959 return d_obtain_alias(inode);
Christoph Hellwig25961102007-10-21 16:42:05 -0700960}
961EXPORT_SYMBOL_GPL(generic_fh_to_parent);
962
Christoph Hellwig1b061d92010-05-26 17:53:41 +0200963/**
Fabian Frederickac13a822014-06-04 16:06:27 -0700964 * __generic_file_fsync - generic fsync implementation for simple filesystems
965 *
Christoph Hellwig1b061d92010-05-26 17:53:41 +0200966 * @file: file to synchronize
Fabian Frederickac13a822014-06-04 16:06:27 -0700967 * @start: start offset in bytes
968 * @end: end offset in bytes (inclusive)
Christoph Hellwig1b061d92010-05-26 17:53:41 +0200969 * @datasync: only synchronize essential metadata if true
970 *
971 * This is a generic implementation of the fsync method for simple
972 * filesystems which track all non-inode metadata in the buffers list
973 * hanging off the address_space structure.
974 */
Fabian Frederickac13a822014-06-04 16:06:27 -0700975int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
976 int datasync)
Al Virod5aacad2009-06-07 14:56:44 -0400977{
Christoph Hellwig7ea80852010-05-26 17:53:25 +0200978 struct inode *inode = file->f_mapping->host;
Al Virod5aacad2009-06-07 14:56:44 -0400979 int err;
980 int ret;
981
Josef Bacik02c24a82011-07-16 20:44:56 -0400982 err = filemap_write_and_wait_range(inode->i_mapping, start, end);
983 if (err)
984 return err;
985
Al Viro59551022016-01-22 15:40:57 -0500986 inode_lock(inode);
Al Virod5aacad2009-06-07 14:56:44 -0400987 ret = sync_mapping_buffers(inode->i_mapping);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -0500988 if (!(inode->i_state & I_DIRTY_ALL))
Josef Bacik02c24a82011-07-16 20:44:56 -0400989 goto out;
Al Virod5aacad2009-06-07 14:56:44 -0400990 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
Josef Bacik02c24a82011-07-16 20:44:56 -0400991 goto out;
Al Virod5aacad2009-06-07 14:56:44 -0400992
Christoph Hellwigc37650162010-10-06 10:48:20 +0200993 err = sync_inode_metadata(inode, 1);
Al Virod5aacad2009-06-07 14:56:44 -0400994 if (ret == 0)
995 ret = err;
Fabian Frederickac13a822014-06-04 16:06:27 -0700996
Josef Bacik02c24a82011-07-16 20:44:56 -0400997out:
Al Viro59551022016-01-22 15:40:57 -0500998 inode_unlock(inode);
Al Virod5aacad2009-06-07 14:56:44 -0400999 return ret;
1000}
Fabian Frederickac13a822014-06-04 16:06:27 -07001001EXPORT_SYMBOL(__generic_file_fsync);
1002
1003/**
1004 * generic_file_fsync - generic fsync implementation for simple filesystems
1005 * with flush
1006 * @file: file to synchronize
1007 * @start: start offset in bytes
1008 * @end: end offset in bytes (inclusive)
1009 * @datasync: only synchronize essential metadata if true
1010 *
1011 */
1012
1013int generic_file_fsync(struct file *file, loff_t start, loff_t end,
1014 int datasync)
1015{
1016 struct inode *inode = file->f_mapping->host;
1017 int err;
1018
1019 err = __generic_file_fsync(file, start, end, datasync);
1020 if (err)
1021 return err;
1022 return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
1023}
Christoph Hellwig1b061d92010-05-26 17:53:41 +02001024EXPORT_SYMBOL(generic_file_fsync);
1025
Patrick J. LoPresti30ca22c2010-07-22 15:03:41 -07001026/**
1027 * generic_check_addressable - Check addressability of file system
1028 * @blocksize_bits: log of file system block size
1029 * @num_blocks: number of blocks in file system
1030 *
1031 * Determine whether a file system with @num_blocks blocks (and a
1032 * block size of 2**@blocksize_bits) is addressable by the sector_t
1033 * and page cache of the system. Return 0 if so and -EFBIG otherwise.
1034 */
1035int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
1036{
1037 u64 last_fs_block = num_blocks - 1;
Joel Beckera33f13e2010-08-16 12:10:17 -07001038 u64 last_fs_page =
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001039 last_fs_block >> (PAGE_SHIFT - blocksize_bits);
Patrick J. LoPresti30ca22c2010-07-22 15:03:41 -07001040
1041 if (unlikely(num_blocks == 0))
1042 return 0;
1043
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001044 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
Patrick J. LoPresti30ca22c2010-07-22 15:03:41 -07001045 return -EINVAL;
1046
Joel Beckera33f13e2010-08-16 12:10:17 -07001047 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
1048 (last_fs_page > (pgoff_t)(~0ULL))) {
Patrick J. LoPresti30ca22c2010-07-22 15:03:41 -07001049 return -EFBIG;
1050 }
1051 return 0;
1052}
1053EXPORT_SYMBOL(generic_check_addressable);
1054
Christoph Hellwig1b061d92010-05-26 17:53:41 +02001055/*
1056 * No-op implementation of ->fsync for in-memory filesystems.
1057 */
Josef Bacik02c24a82011-07-16 20:44:56 -04001058int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
Christoph Hellwig1b061d92010-05-26 17:53:41 +02001059{
1060 return 0;
1061}
Christoph Hellwig1b061d92010-05-26 17:53:41 +02001062EXPORT_SYMBOL(noop_fsync);
Al Viro87dc8002013-09-16 10:30:04 -04001063
Al Virofceef392015-12-29 15:58:39 -05001064/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
1065void kfree_link(void *p)
Al Viro87dc8002013-09-16 10:30:04 -04001066{
Al Virofceef392015-12-29 15:58:39 -05001067 kfree(p);
Al Viro87dc8002013-09-16 10:30:04 -04001068}
Al Virofceef392015-12-29 15:58:39 -05001069EXPORT_SYMBOL(kfree_link);
Al Viro69878432013-10-02 22:35:11 -04001070
1071/*
1072 * nop .set_page_dirty method so that people can use .page_mkwrite on
1073 * anon inodes.
1074 */
1075static int anon_set_page_dirty(struct page *page)
1076{
1077 return 0;
1078};
1079
1080/*
1081 * A single inode exists for all anon_inode files. Contrary to pipes,
1082 * anon_inode inodes have no associated per-instance data, so we need
1083 * only allocate one of them.
1084 */
1085struct inode *alloc_anon_inode(struct super_block *s)
1086{
1087 static const struct address_space_operations anon_aops = {
1088 .set_page_dirty = anon_set_page_dirty,
1089 };
1090 struct inode *inode = new_inode_pseudo(s);
1091
1092 if (!inode)
1093 return ERR_PTR(-ENOMEM);
1094
1095 inode->i_ino = get_next_ino();
1096 inode->i_mapping->a_ops = &anon_aops;
1097
1098 /*
1099 * Mark the inode dirty from the very beginning,
1100 * that way it will never be moved to the dirty
1101 * list because mark_inode_dirty() will think
1102 * that it already _is_ on the dirty list.
1103 */
1104 inode->i_state = I_DIRTY;
1105 inode->i_mode = S_IRUSR | S_IWUSR;
1106 inode->i_uid = current_fsuid();
1107 inode->i_gid = current_fsgid();
1108 inode->i_flags |= S_PRIVATE;
Deepa Dinamani078cd822016-09-14 07:48:04 -07001109 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
Al Viro69878432013-10-02 22:35:11 -04001110 return inode;
1111}
1112EXPORT_SYMBOL(alloc_anon_inode);
Jeff Layton1c994a02014-08-27 06:49:41 -04001113
1114/**
1115 * simple_nosetlease - generic helper for prohibiting leases
1116 * @filp: file pointer
1117 * @arg: type of lease to obtain
1118 * @flp: new lease supplied for insertion
Jeff Laytone6f5c782014-08-22 10:40:25 -04001119 * @priv: private data for lm_setup operation
Jeff Layton1c994a02014-08-27 06:49:41 -04001120 *
1121 * Generic helper for filesystems that do not wish to allow leases to be set.
1122 * All arguments are ignored and it just returns -EINVAL.
1123 */
1124int
Jeff Laytone6f5c782014-08-22 10:40:25 -04001125simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
1126 void **priv)
Jeff Layton1c994a02014-08-27 06:49:41 -04001127{
1128 return -EINVAL;
1129}
1130EXPORT_SYMBOL(simple_nosetlease);
Al Viro61ba64f2015-05-02 09:54:06 -04001131
Al Viro6b255392015-11-17 10:20:54 -05001132const char *simple_get_link(struct dentry *dentry, struct inode *inode,
Al Virofceef392015-12-29 15:58:39 -05001133 struct delayed_call *done)
Al Viro61ba64f2015-05-02 09:54:06 -04001134{
Al Viro6b255392015-11-17 10:20:54 -05001135 return inode->i_link;
Al Viro61ba64f2015-05-02 09:54:06 -04001136}
Al Viro6b255392015-11-17 10:20:54 -05001137EXPORT_SYMBOL(simple_get_link);
Al Viro61ba64f2015-05-02 09:54:06 -04001138
1139const struct inode_operations simple_symlink_inode_operations = {
Al Viro6b255392015-11-17 10:20:54 -05001140 .get_link = simple_get_link,
Al Viro61ba64f2015-05-02 09:54:06 -04001141 .readlink = generic_readlink
1142};
1143EXPORT_SYMBOL(simple_symlink_inode_operations);
Eric W. Biedermanfbabfd02015-05-09 15:54:49 -05001144
1145/*
1146 * Operations for a permanently empty directory.
1147 */
1148static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
1149{
1150 return ERR_PTR(-ENOENT);
1151}
1152
1153static int empty_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
1154 struct kstat *stat)
1155{
1156 struct inode *inode = d_inode(dentry);
1157 generic_fillattr(inode, stat);
1158 return 0;
1159}
1160
1161static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
1162{
1163 return -EPERM;
1164}
1165
Eric W. Biedermanfbabfd02015-05-09 15:54:49 -05001166static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
1167{
1168 return -EOPNOTSUPP;
1169}
1170
1171static const struct inode_operations empty_dir_inode_operations = {
1172 .lookup = empty_dir_lookup,
1173 .permission = generic_permission,
1174 .setattr = empty_dir_setattr,
1175 .getattr = empty_dir_getattr,
Eric W. Biedermanfbabfd02015-05-09 15:54:49 -05001176 .listxattr = empty_dir_listxattr,
1177};
1178
1179static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
1180{
1181 /* An empty directory has two entries . and .. at offsets 0 and 1 */
1182 return generic_file_llseek_size(file, offset, whence, 2, 2);
1183}
1184
1185static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
1186{
1187 dir_emit_dots(file, ctx);
1188 return 0;
1189}
1190
1191static const struct file_operations empty_dir_operations = {
1192 .llseek = empty_dir_llseek,
1193 .read = generic_read_dir,
Al Viroc51da202016-04-30 22:37:34 -04001194 .iterate_shared = empty_dir_readdir,
Eric W. Biedermanfbabfd02015-05-09 15:54:49 -05001195 .fsync = noop_fsync,
1196};
1197
1198
1199void make_empty_dir_inode(struct inode *inode)
1200{
1201 set_nlink(inode, 2);
1202 inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
1203 inode->i_uid = GLOBAL_ROOT_UID;
1204 inode->i_gid = GLOBAL_ROOT_GID;
1205 inode->i_rdev = 0;
Eric W. Biederman4b75de862015-08-12 15:00:12 -05001206 inode->i_size = 0;
Eric W. Biedermanfbabfd02015-05-09 15:54:49 -05001207 inode->i_blkbits = PAGE_SHIFT;
1208 inode->i_blocks = 0;
1209
1210 inode->i_op = &empty_dir_inode_operations;
Andreas Gruenbacherf5c24432016-09-29 17:48:41 +02001211 inode->i_opflags &= ~IOP_XATTR;
Eric W. Biedermanfbabfd02015-05-09 15:54:49 -05001212 inode->i_fop = &empty_dir_operations;
1213}
1214
1215bool is_empty_dir_inode(struct inode *inode)
1216{
1217 return (inode->i_fop == &empty_dir_operations) &&
1218 (inode->i_op == &empty_dir_inode_operations);
1219}