1 /*
2 * fs/sdcardfs/file.c
3 *
4 * Copyright (c) 2013 Samsung Electronics Co. Ltd
5 * Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
6 * Sunghwan Yun, Sungjong Seo
7 *
8 * This program has been developed as a stackable file system based on
9 * the WrapFS which written by
10 *
11 * Copyright (c) 1998-2011 Erez Zadok
12 * Copyright (c) 2009 Shrikar Archak
13 * Copyright (c) 2003-2011 Stony Brook University
14 * Copyright (c) 2003-2011 The Research Foundation of SUNY
15 *
16 * This file is dual licensed. It may be redistributed and/or modified
17 * under the terms of the Apache 2.0 License OR version 2 of the GNU
18 * General Public License.
19 */
20
21 #include "sdcardfs.h"
22 #ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
23 #include <linux/backing-dev.h>
24 #endif
25
sdcardfs_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)26 static ssize_t sdcardfs_read(struct file *file, char __user *buf,
27 size_t count, loff_t *ppos)
28 {
29 int err;
30 struct file *lower_file;
31 struct dentry *dentry = file->f_path.dentry;
32 #ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
33 struct backing_dev_info *bdi;
34 #endif
35
36 lower_file = sdcardfs_lower_file(file);
37
38 #ifdef CONFIG_SDCARD_FS_FADV_NOACTIVE
39 if (file->f_mode & FMODE_NOACTIVE) {
40 if (!(lower_file->f_mode & FMODE_NOACTIVE)) {
41 bdi = lower_file->f_mapping->backing_dev_info;
42 lower_file->f_ra.ra_pages = bdi->ra_pages * 2;
43 spin_lock(&lower_file->f_lock);
44 lower_file->f_mode |= FMODE_NOACTIVE;
45 spin_unlock(&lower_file->f_lock);
46 }
47 }
48 #endif
49
50 err = vfs_read(lower_file, buf, count, ppos);
51 /* update our inode atime upon a successful lower read */
52 if (err >= 0)
53 fsstack_copy_attr_atime(d_inode(dentry),
54 file_inode(lower_file));
55
56 return err;
57 }
58
sdcardfs_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)59 static ssize_t sdcardfs_write(struct file *file, const char __user *buf,
60 size_t count, loff_t *ppos)
61 {
62 int err;
63 struct file *lower_file;
64 struct dentry *dentry = file->f_path.dentry;
65 struct inode *inode = d_inode(dentry);
66
67 /* check disk space */
68 if (!check_min_free_space(dentry, count, 0)) {
69 pr_err("No minimum free space.\n");
70 return -ENOSPC;
71 }
72
73 lower_file = sdcardfs_lower_file(file);
74 err = vfs_write(lower_file, buf, count, ppos);
75 /* update our inode times+sizes upon a successful lower write */
76 if (err >= 0) {
77 if (sizeof(loff_t) > sizeof(long))
78 inode_lock(inode);
79 fsstack_copy_inode_size(inode, file_inode(lower_file));
80 fsstack_copy_attr_times(inode, file_inode(lower_file));
81 if (sizeof(loff_t) > sizeof(long))
82 inode_unlock(inode);
83 }
84
85 return err;
86 }
87
sdcardfs_readdir(struct file * file,struct dir_context * ctx)88 static int sdcardfs_readdir(struct file *file, struct dir_context *ctx)
89 {
90 int err;
91 struct file *lower_file = NULL;
92 struct dentry *dentry = file->f_path.dentry;
93
94 lower_file = sdcardfs_lower_file(file);
95
96 lower_file->f_pos = file->f_pos;
97 err = iterate_dir(lower_file, ctx);
98 file->f_pos = lower_file->f_pos;
99 if (err >= 0) /* copy the atime */
100 fsstack_copy_attr_atime(d_inode(dentry),
101 file_inode(lower_file));
102 return err;
103 }
104
sdcardfs_unlocked_ioctl(struct file * file,unsigned int cmd,unsigned long arg)105 static long sdcardfs_unlocked_ioctl(struct file *file, unsigned int cmd,
106 unsigned long arg)
107 {
108 long err = -ENOTTY;
109 struct file *lower_file;
110 const struct cred *saved_cred = NULL;
111 struct dentry *dentry = file->f_path.dentry;
112 struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
113
114 lower_file = sdcardfs_lower_file(file);
115
116 /* XXX: use vfs_ioctl if/when VFS exports it */
117 if (!lower_file || !lower_file->f_op)
118 goto out;
119
120 /* save current_cred and override it */
121 saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
122 if (!saved_cred) {
123 err = -ENOMEM;
124 goto out;
125 }
126
127 if (lower_file->f_op->unlocked_ioctl)
128 err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
129
130 /* some ioctls can change inode attributes (EXT2_IOC_SETFLAGS) */
131 if (!err)
132 sdcardfs_copy_and_fix_attrs(file_inode(file),
133 file_inode(lower_file));
134 revert_fsids(saved_cred);
135 out:
136 return err;
137 }
138
139 #ifdef CONFIG_COMPAT
sdcardfs_compat_ioctl(struct file * file,unsigned int cmd,unsigned long arg)140 static long sdcardfs_compat_ioctl(struct file *file, unsigned int cmd,
141 unsigned long arg)
142 {
143 long err = -ENOTTY;
144 struct file *lower_file;
145 const struct cred *saved_cred = NULL;
146 struct dentry *dentry = file->f_path.dentry;
147 struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
148
149 lower_file = sdcardfs_lower_file(file);
150
151 /* XXX: use vfs_ioctl if/when VFS exports it */
152 if (!lower_file || !lower_file->f_op)
153 goto out;
154
155 /* save current_cred and override it */
156 saved_cred = override_fsids(sbi, SDCARDFS_I(file_inode(file))->data);
157 if (!saved_cred) {
158 err = -ENOMEM;
159 goto out;
160 }
161
162 if (lower_file->f_op->compat_ioctl)
163 err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
164
165 revert_fsids(saved_cred);
166 out:
167 return err;
168 }
169 #endif
170
sdcardfs_mmap(struct file * file,struct vm_area_struct * vma)171 static int sdcardfs_mmap(struct file *file, struct vm_area_struct *vma)
172 {
173 int err = 0;
174 bool willwrite;
175 struct file *lower_file;
176 const struct vm_operations_struct *saved_vm_ops = NULL;
177
178 /* this might be deferred to mmap's writepage */
179 willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
180
181 /*
182 * File systems which do not implement ->writepage may use
183 * generic_file_readonly_mmap as their ->mmap op. If you call
184 * generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
185 * But we cannot call the lower ->mmap op, so we can't tell that
186 * writeable mappings won't work. Therefore, our only choice is to
187 * check if the lower file system supports the ->writepage, and if
188 * not, return EINVAL (the same error that
189 * generic_file_readonly_mmap returns in that case).
190 */
191 lower_file = sdcardfs_lower_file(file);
192 if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
193 err = -EINVAL;
194 pr_err("sdcardfs: lower file system does not support writeable mmap\n");
195 goto out;
196 }
197
198 /*
199 * find and save lower vm_ops.
200 *
201 * XXX: the VFS should have a cleaner way of finding the lower vm_ops
202 */
203 if (!SDCARDFS_F(file)->lower_vm_ops) {
204 err = lower_file->f_op->mmap(lower_file, vma);
205 if (err) {
206 pr_err("sdcardfs: lower mmap failed %d\n", err);
207 goto out;
208 }
209 saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */
210 }
211
212 /*
213 * Next 3 lines are all I need from generic_file_mmap. I definitely
214 * don't want its test for ->readpage which returns -ENOEXEC.
215 */
216 file_accessed(file);
217 vma->vm_ops = &sdcardfs_vm_ops;
218
219 file->f_mapping->a_ops = &sdcardfs_aops; /* set our aops */
220 if (!SDCARDFS_F(file)->lower_vm_ops) /* save for our ->fault */
221 SDCARDFS_F(file)->lower_vm_ops = saved_vm_ops;
222 vma->vm_private_data = file;
223 get_file(lower_file);
224 vma->vm_file = lower_file;
225
226 out:
227 return err;
228 }
229
sdcardfs_open(struct inode * inode,struct file * file)230 static int sdcardfs_open(struct inode *inode, struct file *file)
231 {
232 int err = 0;
233 struct file *lower_file = NULL;
234 struct path lower_path;
235 struct dentry *dentry = file->f_path.dentry;
236 struct dentry *parent = dget_parent(dentry);
237 struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
238 const struct cred *saved_cred = NULL;
239
240 /* don't open unhashed/deleted files */
241 if (d_unhashed(dentry)) {
242 err = -ENOENT;
243 goto out_err;
244 }
245
246 if (!check_caller_access_to_name(d_inode(parent), &dentry->d_name)) {
247 err = -EACCES;
248 goto out_err;
249 }
250
251 /* save current_cred and override it */
252 saved_cred = override_fsids(sbi, SDCARDFS_I(inode)->data);
253 if (!saved_cred) {
254 err = -ENOMEM;
255 goto out_err;
256 }
257
258 file->private_data =
259 kzalloc(sizeof(struct sdcardfs_file_info), GFP_KERNEL);
260 if (!SDCARDFS_F(file)) {
261 err = -ENOMEM;
262 goto out_revert_cred;
263 }
264
265 /* open lower object and link sdcardfs's file struct to lower's */
266 sdcardfs_get_lower_path(file->f_path.dentry, &lower_path);
267 lower_file = dentry_open(&lower_path, file->f_flags, current_cred());
268 path_put(&lower_path);
269 if (IS_ERR(lower_file)) {
270 err = PTR_ERR(lower_file);
271 lower_file = sdcardfs_lower_file(file);
272 if (lower_file) {
273 sdcardfs_set_lower_file(file, NULL);
274 fput(lower_file); /* fput calls dput for lower_dentry */
275 }
276 } else {
277 sdcardfs_set_lower_file(file, lower_file);
278 }
279
280 if (err)
281 kfree(SDCARDFS_F(file));
282 else
283 sdcardfs_copy_and_fix_attrs(inode, sdcardfs_lower_inode(inode));
284
285 out_revert_cred:
286 revert_fsids(saved_cred);
287 out_err:
288 dput(parent);
289 return err;
290 }
291
sdcardfs_flush(struct file * file,fl_owner_t id)292 static int sdcardfs_flush(struct file *file, fl_owner_t id)
293 {
294 int err = 0;
295 struct file *lower_file = NULL;
296
297 lower_file = sdcardfs_lower_file(file);
298 if (lower_file && lower_file->f_op && lower_file->f_op->flush) {
299 filemap_write_and_wait(file->f_mapping);
300 err = lower_file->f_op->flush(lower_file, id);
301 }
302
303 return err;
304 }
305
306 /* release all lower object references & free the file info structure */
sdcardfs_file_release(struct inode * inode,struct file * file)307 static int sdcardfs_file_release(struct inode *inode, struct file *file)
308 {
309 struct file *lower_file;
310
311 lower_file = sdcardfs_lower_file(file);
312 if (lower_file) {
313 sdcardfs_set_lower_file(file, NULL);
314 fput(lower_file);
315 }
316
317 kfree(SDCARDFS_F(file));
318 return 0;
319 }
320
sdcardfs_fsync(struct file * file,loff_t start,loff_t end,int datasync)321 static int sdcardfs_fsync(struct file *file, loff_t start, loff_t end,
322 int datasync)
323 {
324 int err;
325 struct file *lower_file;
326 struct path lower_path;
327 struct dentry *dentry = file->f_path.dentry;
328
329 err = __generic_file_fsync(file, start, end, datasync);
330 if (err)
331 goto out;
332
333 lower_file = sdcardfs_lower_file(file);
334 sdcardfs_get_lower_path(dentry, &lower_path);
335 err = vfs_fsync_range(lower_file, start, end, datasync);
336 sdcardfs_put_lower_path(dentry, &lower_path);
337 out:
338 return err;
339 }
340
sdcardfs_fasync(int fd,struct file * file,int flag)341 static int sdcardfs_fasync(int fd, struct file *file, int flag)
342 {
343 int err = 0;
344 struct file *lower_file = NULL;
345
346 lower_file = sdcardfs_lower_file(file);
347 if (lower_file->f_op && lower_file->f_op->fasync)
348 err = lower_file->f_op->fasync(fd, lower_file, flag);
349
350 return err;
351 }
352
353 /*
354 * Sdcardfs cannot use generic_file_llseek as ->llseek, because it would
355 * only set the offset of the upper file. So we have to implement our
356 * own method to set both the upper and lower file offsets
357 * consistently.
358 */
sdcardfs_file_llseek(struct file * file,loff_t offset,int whence)359 static loff_t sdcardfs_file_llseek(struct file *file, loff_t offset, int whence)
360 {
361 int err;
362 struct file *lower_file;
363
364 err = generic_file_llseek(file, offset, whence);
365 if (err < 0)
366 goto out;
367
368 lower_file = sdcardfs_lower_file(file);
369 err = generic_file_llseek(lower_file, offset, whence);
370
371 out:
372 return err;
373 }
374
375 /*
376 * Sdcardfs read_iter, redirect modified iocb to lower read_iter
377 */
sdcardfs_read_iter(struct kiocb * iocb,struct iov_iter * iter)378 ssize_t sdcardfs_read_iter(struct kiocb *iocb, struct iov_iter *iter)
379 {
380 int err;
381 struct file *file = iocb->ki_filp, *lower_file;
382
383 lower_file = sdcardfs_lower_file(file);
384 if (!lower_file->f_op->read_iter) {
385 err = -EINVAL;
386 goto out;
387 }
388
389 get_file(lower_file); /* prevent lower_file from being released */
390 iocb->ki_filp = lower_file;
391 err = lower_file->f_op->read_iter(iocb, iter);
392 iocb->ki_filp = file;
393 fput(lower_file);
394 /* update upper inode atime as needed */
395 if (err >= 0 || err == -EIOCBQUEUED)
396 fsstack_copy_attr_atime(file->f_path.dentry->d_inode,
397 file_inode(lower_file));
398 out:
399 return err;
400 }
401
402 /*
403 * Sdcardfs write_iter, redirect modified iocb to lower write_iter
404 */
sdcardfs_write_iter(struct kiocb * iocb,struct iov_iter * iter)405 ssize_t sdcardfs_write_iter(struct kiocb *iocb, struct iov_iter *iter)
406 {
407 int err;
408 struct file *file = iocb->ki_filp, *lower_file;
409 struct inode *inode = file->f_path.dentry->d_inode;
410
411 lower_file = sdcardfs_lower_file(file);
412 if (!lower_file->f_op->write_iter) {
413 err = -EINVAL;
414 goto out;
415 }
416
417 get_file(lower_file); /* prevent lower_file from being released */
418 iocb->ki_filp = lower_file;
419 err = lower_file->f_op->write_iter(iocb, iter);
420 iocb->ki_filp = file;
421 fput(lower_file);
422 /* update upper inode times/sizes as needed */
423 if (err >= 0 || err == -EIOCBQUEUED) {
424 if (sizeof(loff_t) > sizeof(long))
425 inode_lock(inode);
426 fsstack_copy_inode_size(inode, file_inode(lower_file));
427 fsstack_copy_attr_times(inode, file_inode(lower_file));
428 if (sizeof(loff_t) > sizeof(long))
429 inode_unlock(inode);
430 }
431 out:
432 return err;
433 }
434
435 const struct file_operations sdcardfs_main_fops = {
436 .llseek = generic_file_llseek,
437 .read = sdcardfs_read,
438 .write = sdcardfs_write,
439 .unlocked_ioctl = sdcardfs_unlocked_ioctl,
440 #ifdef CONFIG_COMPAT
441 .compat_ioctl = sdcardfs_compat_ioctl,
442 #endif
443 .mmap = sdcardfs_mmap,
444 .open = sdcardfs_open,
445 .flush = sdcardfs_flush,
446 .release = sdcardfs_file_release,
447 .fsync = sdcardfs_fsync,
448 .fasync = sdcardfs_fasync,
449 .read_iter = sdcardfs_read_iter,
450 .write_iter = sdcardfs_write_iter,
451 };
452
453 /* trimmed directory options */
454 const struct file_operations sdcardfs_dir_fops = {
455 .llseek = sdcardfs_file_llseek,
456 .read = generic_read_dir,
457 .iterate = sdcardfs_readdir,
458 .unlocked_ioctl = sdcardfs_unlocked_ioctl,
459 #ifdef CONFIG_COMPAT
460 .compat_ioctl = sdcardfs_compat_ioctl,
461 #endif
462 .open = sdcardfs_open,
463 .release = sdcardfs_file_release,
464 .flush = sdcardfs_flush,
465 .fsync = sdcardfs_fsync,
466 .fasync = sdcardfs_fasync,
467 };
468