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1// SPDX-License-Identifier: MIT
2/*
3 * VirtualBox Guest Shared Folders support: Regular file inode and file ops.
4 *
5 * Copyright (C) 2006-2018 Oracle Corporation
6 */
7
8#include <linux/mm.h>
9#include <linux/page-flags.h>
10#include <linux/pagemap.h>
11#include <linux/highmem.h>
12#include <linux/sizes.h>
13#include "vfsmod.h"
14
15struct vboxsf_handle {
16 u64 handle;
17 u32 root;
18 u32 access_flags;
19 struct kref refcount;
20 struct list_head head;
21};
22
23static int vboxsf_file_open(struct inode *inode, struct file *file)
24{
25 struct vboxsf_inode *sf_i = VBOXSF_I(inode);
26 struct shfl_createparms params = {};
27 struct vboxsf_handle *sf_handle;
28 u32 access_flags = 0;
29 int err;
30
31 sf_handle = kmalloc(sizeof(*sf_handle), GFP_KERNEL);
32 if (!sf_handle)
33 return -ENOMEM;
34
35 /*
36 * We check the value of params.handle afterwards to find out if
37 * the call succeeded or failed, as the API does not seem to cleanly
38 * distinguish error and informational messages.
39 *
40 * Furthermore, we must set params.handle to SHFL_HANDLE_NIL to
41 * make the shared folders host service use our mode parameter.
42 */
43 params.handle = SHFL_HANDLE_NIL;
44 if (file->f_flags & O_CREAT) {
45 params.create_flags |= SHFL_CF_ACT_CREATE_IF_NEW;
46 /*
47 * We ignore O_EXCL, as the Linux kernel seems to call create
48 * beforehand itself, so O_EXCL should always fail.
49 */
50 if (file->f_flags & O_TRUNC)
51 params.create_flags |= SHFL_CF_ACT_OVERWRITE_IF_EXISTS;
52 else
53 params.create_flags |= SHFL_CF_ACT_OPEN_IF_EXISTS;
54 } else {
55 params.create_flags |= SHFL_CF_ACT_FAIL_IF_NEW;
56 if (file->f_flags & O_TRUNC)
57 params.create_flags |= SHFL_CF_ACT_OVERWRITE_IF_EXISTS;
58 }
59
60 switch (file->f_flags & O_ACCMODE) {
61 case O_RDONLY:
62 access_flags |= SHFL_CF_ACCESS_READ;
63 break;
64
65 case O_WRONLY:
66 access_flags |= SHFL_CF_ACCESS_WRITE;
67 break;
68
69 case O_RDWR:
70 access_flags |= SHFL_CF_ACCESS_READWRITE;
71 break;
72
73 default:
74 WARN_ON(1);
75 }
76
77 if (file->f_flags & O_APPEND)
78 access_flags |= SHFL_CF_ACCESS_APPEND;
79
80 params.create_flags |= access_flags;
81 params.info.attr.mode = inode->i_mode;
82
83 err = vboxsf_create_at_dentry(file_dentry(file), ¶ms);
84 if (err == 0 && params.handle == SHFL_HANDLE_NIL)
85 err = (params.result == SHFL_FILE_EXISTS) ? -EEXIST : -ENOENT;
86 if (err) {
87 kfree(sf_handle);
88 return err;
89 }
90
91 /* the host may have given us different attr then requested */
92 sf_i->force_restat = 1;
93
94 /* init our handle struct and add it to the inode's handles list */
95 sf_handle->handle = params.handle;
96 sf_handle->root = VBOXSF_SBI(inode->i_sb)->root;
97 sf_handle->access_flags = access_flags;
98 kref_init(&sf_handle->refcount);
99
100 mutex_lock(&sf_i->handle_list_mutex);
101 list_add(&sf_handle->head, &sf_i->handle_list);
102 mutex_unlock(&sf_i->handle_list_mutex);
103
104 file->private_data = sf_handle;
105 return 0;
106}
107
108static void vboxsf_handle_release(struct kref *refcount)
109{
110 struct vboxsf_handle *sf_handle =
111 container_of(refcount, struct vboxsf_handle, refcount);
112
113 vboxsf_close(sf_handle->root, sf_handle->handle);
114 kfree(sf_handle);
115}
116
117static int vboxsf_file_release(struct inode *inode, struct file *file)
118{
119 struct vboxsf_inode *sf_i = VBOXSF_I(inode);
120 struct vboxsf_handle *sf_handle = file->private_data;
121
122 /*
123 * When a file is closed on our (the guest) side, we want any subsequent
124 * accesses done on the host side to see all changes done from our side.
125 */
126 filemap_write_and_wait(inode->i_mapping);
127
128 mutex_lock(&sf_i->handle_list_mutex);
129 list_del(&sf_handle->head);
130 mutex_unlock(&sf_i->handle_list_mutex);
131
132 kref_put(&sf_handle->refcount, vboxsf_handle_release);
133 return 0;
134}
135
136/*
137 * Write back dirty pages now, because there may not be any suitable
138 * open files later
139 */
140static void vboxsf_vma_close(struct vm_area_struct *vma)
141{
142 filemap_write_and_wait(vma->vm_file->f_mapping);
143}
144
145static const struct vm_operations_struct vboxsf_file_vm_ops = {
146 .close = vboxsf_vma_close,
147 .fault = filemap_fault,
148 .map_pages = filemap_map_pages,
149};
150
151static int vboxsf_file_mmap(struct file *file, struct vm_area_struct *vma)
152{
153 int err;
154
155 err = generic_file_mmap(file, vma);
156 if (!err)
157 vma->vm_ops = &vboxsf_file_vm_ops;
158
159 return err;
160}
161
162/*
163 * Note that since we are accessing files on the host's filesystem, files
164 * may always be changed underneath us by the host!
165 *
166 * The vboxsf API between the guest and the host does not offer any functions
167 * to deal with this. There is no inode-generation to check for changes, no
168 * events / callback on changes and no way to lock files.
169 *
170 * To avoid returning stale data when a file gets *opened* on our (the guest)
171 * side, we do a "stat" on the host side, then compare the mtime with the
172 * last known mtime and invalidate the page-cache if they differ.
173 * This is done from vboxsf_inode_revalidate().
174 *
175 * When reads are done through the read_iter fop, it is possible to do
176 * further cache revalidation then, there are 3 options to deal with this:
177 *
178 * 1) Rely solely on the revalidation done at open time
179 * 2) Do another "stat" and compare mtime again. Unfortunately the vboxsf
180 * host API does not allow stat on handles, so we would need to use
181 * file->f_path.dentry and the stat will then fail if the file was unlinked
182 * or renamed (and there is no thing like NFS' silly-rename). So we get:
183 * 2a) "stat" and compare mtime, on stat failure invalidate the cache
184 * 2b) "stat" and compare mtime, on stat failure do nothing
185 * 3) Simply always call invalidate_inode_pages2_range on the range of the read
186 *
187 * Currently we are keeping things KISS and using option 1. this allows
188 * directly using generic_file_read_iter without wrapping it.
189 *
190 * This means that only data written on the host side before open() on
191 * the guest side is guaranteed to be seen by the guest. If necessary
192 * we may provide other read-cache strategies in the future and make this
193 * configurable through a mount option.
194 */
195const struct file_operations vboxsf_reg_fops = {
196 .llseek = generic_file_llseek,
197 .read_iter = generic_file_read_iter,
198 .write_iter = generic_file_write_iter,
199 .mmap = vboxsf_file_mmap,
200 .open = vboxsf_file_open,
201 .release = vboxsf_file_release,
202 .fsync = noop_fsync,
203 .splice_read = generic_file_splice_read,
204};
205
206const struct inode_operations vboxsf_reg_iops = {
207 .getattr = vboxsf_getattr,
208 .setattr = vboxsf_setattr
209};
210
211static int vboxsf_readpage(struct file *file, struct page *page)
212{
213 struct vboxsf_handle *sf_handle = file->private_data;
214 loff_t off = page_offset(page);
215 u32 nread = PAGE_SIZE;
216 u8 *buf;
217 int err;
218
219 buf = kmap(page);
220
221 err = vboxsf_read(sf_handle->root, sf_handle->handle, off, &nread, buf);
222 if (err == 0) {
223 memset(&buf[nread], 0, PAGE_SIZE - nread);
224 flush_dcache_page(page);
225 SetPageUptodate(page);
226 } else {
227 SetPageError(page);
228 }
229
230 kunmap(page);
231 unlock_page(page);
232 return err;
233}
234
235static struct vboxsf_handle *vboxsf_get_write_handle(struct vboxsf_inode *sf_i)
236{
237 struct vboxsf_handle *h, *sf_handle = NULL;
238
239 mutex_lock(&sf_i->handle_list_mutex);
240 list_for_each_entry(h, &sf_i->handle_list, head) {
241 if (h->access_flags == SHFL_CF_ACCESS_WRITE ||
242 h->access_flags == SHFL_CF_ACCESS_READWRITE) {
243 kref_get(&h->refcount);
244 sf_handle = h;
245 break;
246 }
247 }
248 mutex_unlock(&sf_i->handle_list_mutex);
249
250 return sf_handle;
251}
252
253static int vboxsf_writepage(struct page *page, struct writeback_control *wbc)
254{
255 struct inode *inode = page->mapping->host;
256 struct vboxsf_inode *sf_i = VBOXSF_I(inode);
257 struct vboxsf_handle *sf_handle;
258 loff_t off = page_offset(page);
259 loff_t size = i_size_read(inode);
260 u32 nwrite = PAGE_SIZE;
261 u8 *buf;
262 int err;
263
264 if (off + PAGE_SIZE > size)
265 nwrite = size & ~PAGE_MASK;
266
267 sf_handle = vboxsf_get_write_handle(sf_i);
268 if (!sf_handle)
269 return -EBADF;
270
271 buf = kmap(page);
272 err = vboxsf_write(sf_handle->root, sf_handle->handle,
273 off, &nwrite, buf);
274 kunmap(page);
275
276 kref_put(&sf_handle->refcount, vboxsf_handle_release);
277
278 if (err == 0) {
279 ClearPageError(page);
280 /* mtime changed */
281 sf_i->force_restat = 1;
282 } else {
283 ClearPageUptodate(page);
284 }
285
286 unlock_page(page);
287 return err;
288}
289
290static int vboxsf_write_end(struct file *file, struct address_space *mapping,
291 loff_t pos, unsigned int len, unsigned int copied,
292 struct page *page, void *fsdata)
293{
294 struct inode *inode = mapping->host;
295 struct vboxsf_handle *sf_handle = file->private_data;
296 unsigned int from = pos & ~PAGE_MASK;
297 u32 nwritten = len;
298 u8 *buf;
299 int err;
300
301 /* zero the stale part of the page if we did a short copy */
302 if (!PageUptodate(page) && copied < len)
303 zero_user(page, from + copied, len - copied);
304
305 buf = kmap(page);
306 err = vboxsf_write(sf_handle->root, sf_handle->handle,
307 pos, &nwritten, buf + from);
308 kunmap(page);
309
310 if (err) {
311 nwritten = 0;
312 goto out;
313 }
314
315 /* mtime changed */
316 VBOXSF_I(inode)->force_restat = 1;
317
318 if (!PageUptodate(page) && nwritten == PAGE_SIZE)
319 SetPageUptodate(page);
320
321 pos += nwritten;
322 if (pos > inode->i_size)
323 i_size_write(inode, pos);
324
325out:
326 unlock_page(page);
327 put_page(page);
328
329 return nwritten;
330}
331
332/*
333 * Note simple_write_begin does not read the page from disk on partial writes
334 * this is ok since vboxsf_write_end only writes the written parts of the
335 * page and it does not call SetPageUptodate for partial writes.
336 */
337const struct address_space_operations vboxsf_reg_aops = {
338 .readpage = vboxsf_readpage,
339 .writepage = vboxsf_writepage,
340 .set_page_dirty = __set_page_dirty_nobuffers,
341 .write_begin = simple_write_begin,
342 .write_end = vboxsf_write_end,
343};
344
345static const char *vboxsf_get_link(struct dentry *dentry, struct inode *inode,
346 struct delayed_call *done)
347{
348 struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
349 struct shfl_string *path;
350 char *link;
351 int err;
352
353 if (!dentry)
354 return ERR_PTR(-ECHILD);
355
356 path = vboxsf_path_from_dentry(sbi, dentry);
357 if (IS_ERR(path))
358 return ERR_CAST(path);
359
360 link = kzalloc(PATH_MAX, GFP_KERNEL);
361 if (!link) {
362 __putname(path);
363 return ERR_PTR(-ENOMEM);
364 }
365
366 err = vboxsf_readlink(sbi->root, path, PATH_MAX, link);
367 __putname(path);
368 if (err) {
369 kfree(link);
370 return ERR_PTR(err);
371 }
372
373 set_delayed_call(done, kfree_link, link);
374 return link;
375}
376
377const struct inode_operations vboxsf_lnk_iops = {
378 .get_link = vboxsf_get_link
379};
1// SPDX-License-Identifier: MIT
2/*
3 * VirtualBox Guest Shared Folders support: Regular file inode and file ops.
4 *
5 * Copyright (C) 2006-2018 Oracle Corporation
6 */
7
8#include <linux/mm.h>
9#include <linux/page-flags.h>
10#include <linux/pagemap.h>
11#include <linux/highmem.h>
12#include <linux/sizes.h>
13#include "vfsmod.h"
14
15struct vboxsf_handle {
16 u64 handle;
17 u32 root;
18 u32 access_flags;
19 struct kref refcount;
20 struct list_head head;
21};
22
23struct vboxsf_handle *vboxsf_create_sf_handle(struct inode *inode,
24 u64 handle, u32 access_flags)
25{
26 struct vboxsf_inode *sf_i = VBOXSF_I(inode);
27 struct vboxsf_handle *sf_handle;
28
29 sf_handle = kmalloc(sizeof(*sf_handle), GFP_KERNEL);
30 if (!sf_handle)
31 return ERR_PTR(-ENOMEM);
32
33 /* the host may have given us different attr then requested */
34 sf_i->force_restat = 1;
35
36 /* init our handle struct and add it to the inode's handles list */
37 sf_handle->handle = handle;
38 sf_handle->root = VBOXSF_SBI(inode->i_sb)->root;
39 sf_handle->access_flags = access_flags;
40 kref_init(&sf_handle->refcount);
41
42 mutex_lock(&sf_i->handle_list_mutex);
43 list_add(&sf_handle->head, &sf_i->handle_list);
44 mutex_unlock(&sf_i->handle_list_mutex);
45
46 return sf_handle;
47}
48
49static int vboxsf_file_open(struct inode *inode, struct file *file)
50{
51 struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
52 struct shfl_createparms params = {};
53 struct vboxsf_handle *sf_handle;
54 u32 access_flags = 0;
55 int err;
56
57 /*
58 * We check the value of params.handle afterwards to find out if
59 * the call succeeded or failed, as the API does not seem to cleanly
60 * distinguish error and informational messages.
61 *
62 * Furthermore, we must set params.handle to SHFL_HANDLE_NIL to
63 * make the shared folders host service use our mode parameter.
64 */
65 params.handle = SHFL_HANDLE_NIL;
66 if (file->f_flags & O_CREAT) {
67 params.create_flags |= SHFL_CF_ACT_CREATE_IF_NEW;
68 /*
69 * We ignore O_EXCL, as the Linux kernel seems to call create
70 * beforehand itself, so O_EXCL should always fail.
71 */
72 if (file->f_flags & O_TRUNC)
73 params.create_flags |= SHFL_CF_ACT_OVERWRITE_IF_EXISTS;
74 else
75 params.create_flags |= SHFL_CF_ACT_OPEN_IF_EXISTS;
76 } else {
77 params.create_flags |= SHFL_CF_ACT_FAIL_IF_NEW;
78 if (file->f_flags & O_TRUNC)
79 params.create_flags |= SHFL_CF_ACT_OVERWRITE_IF_EXISTS;
80 }
81
82 switch (file->f_flags & O_ACCMODE) {
83 case O_RDONLY:
84 access_flags |= SHFL_CF_ACCESS_READ;
85 break;
86
87 case O_WRONLY:
88 access_flags |= SHFL_CF_ACCESS_WRITE;
89 break;
90
91 case O_RDWR:
92 access_flags |= SHFL_CF_ACCESS_READWRITE;
93 break;
94
95 default:
96 WARN_ON(1);
97 }
98
99 if (file->f_flags & O_APPEND)
100 access_flags |= SHFL_CF_ACCESS_APPEND;
101
102 params.create_flags |= access_flags;
103 params.info.attr.mode = inode->i_mode;
104
105 err = vboxsf_create_at_dentry(file_dentry(file), ¶ms);
106 if (err == 0 && params.handle == SHFL_HANDLE_NIL)
107 err = (params.result == SHFL_FILE_EXISTS) ? -EEXIST : -ENOENT;
108 if (err)
109 return err;
110
111 sf_handle = vboxsf_create_sf_handle(inode, params.handle, access_flags);
112 if (IS_ERR(sf_handle)) {
113 vboxsf_close(sbi->root, params.handle);
114 return PTR_ERR(sf_handle);
115 }
116
117 file->private_data = sf_handle;
118 return 0;
119}
120
121static void vboxsf_handle_release(struct kref *refcount)
122{
123 struct vboxsf_handle *sf_handle =
124 container_of(refcount, struct vboxsf_handle, refcount);
125
126 vboxsf_close(sf_handle->root, sf_handle->handle);
127 kfree(sf_handle);
128}
129
130void vboxsf_release_sf_handle(struct inode *inode, struct vboxsf_handle *sf_handle)
131{
132 struct vboxsf_inode *sf_i = VBOXSF_I(inode);
133
134 mutex_lock(&sf_i->handle_list_mutex);
135 list_del(&sf_handle->head);
136 mutex_unlock(&sf_i->handle_list_mutex);
137
138 kref_put(&sf_handle->refcount, vboxsf_handle_release);
139}
140
141static int vboxsf_file_release(struct inode *inode, struct file *file)
142{
143 /*
144 * When a file is closed on our (the guest) side, we want any subsequent
145 * accesses done on the host side to see all changes done from our side.
146 */
147 filemap_write_and_wait(inode->i_mapping);
148
149 vboxsf_release_sf_handle(inode, file->private_data);
150 return 0;
151}
152
153/*
154 * Write back dirty pages now, because there may not be any suitable
155 * open files later
156 */
157static void vboxsf_vma_close(struct vm_area_struct *vma)
158{
159 filemap_write_and_wait(vma->vm_file->f_mapping);
160}
161
162static const struct vm_operations_struct vboxsf_file_vm_ops = {
163 .close = vboxsf_vma_close,
164 .fault = filemap_fault,
165 .map_pages = filemap_map_pages,
166};
167
168static int vboxsf_file_mmap(struct file *file, struct vm_area_struct *vma)
169{
170 int err;
171
172 err = generic_file_mmap(file, vma);
173 if (!err)
174 vma->vm_ops = &vboxsf_file_vm_ops;
175
176 return err;
177}
178
179/*
180 * Note that since we are accessing files on the host's filesystem, files
181 * may always be changed underneath us by the host!
182 *
183 * The vboxsf API between the guest and the host does not offer any functions
184 * to deal with this. There is no inode-generation to check for changes, no
185 * events / callback on changes and no way to lock files.
186 *
187 * To avoid returning stale data when a file gets *opened* on our (the guest)
188 * side, we do a "stat" on the host side, then compare the mtime with the
189 * last known mtime and invalidate the page-cache if they differ.
190 * This is done from vboxsf_inode_revalidate().
191 *
192 * When reads are done through the read_iter fop, it is possible to do
193 * further cache revalidation then, there are 3 options to deal with this:
194 *
195 * 1) Rely solely on the revalidation done at open time
196 * 2) Do another "stat" and compare mtime again. Unfortunately the vboxsf
197 * host API does not allow stat on handles, so we would need to use
198 * file->f_path.dentry and the stat will then fail if the file was unlinked
199 * or renamed (and there is no thing like NFS' silly-rename). So we get:
200 * 2a) "stat" and compare mtime, on stat failure invalidate the cache
201 * 2b) "stat" and compare mtime, on stat failure do nothing
202 * 3) Simply always call invalidate_inode_pages2_range on the range of the read
203 *
204 * Currently we are keeping things KISS and using option 1. this allows
205 * directly using generic_file_read_iter without wrapping it.
206 *
207 * This means that only data written on the host side before open() on
208 * the guest side is guaranteed to be seen by the guest. If necessary
209 * we may provide other read-cache strategies in the future and make this
210 * configurable through a mount option.
211 */
212const struct file_operations vboxsf_reg_fops = {
213 .llseek = generic_file_llseek,
214 .read_iter = generic_file_read_iter,
215 .write_iter = generic_file_write_iter,
216 .mmap = vboxsf_file_mmap,
217 .open = vboxsf_file_open,
218 .release = vboxsf_file_release,
219 .fsync = noop_fsync,
220 .splice_read = filemap_splice_read,
221 .setlease = simple_nosetlease,
222};
223
224const struct inode_operations vboxsf_reg_iops = {
225 .getattr = vboxsf_getattr,
226 .setattr = vboxsf_setattr
227};
228
229static int vboxsf_read_folio(struct file *file, struct folio *folio)
230{
231 struct vboxsf_handle *sf_handle = file->private_data;
232 loff_t off = folio_pos(folio);
233 u32 nread = PAGE_SIZE;
234 u8 *buf;
235 int err;
236
237 buf = kmap_local_folio(folio, 0);
238
239 err = vboxsf_read(sf_handle->root, sf_handle->handle, off, &nread, buf);
240 buf = folio_zero_tail(folio, nread, buf + nread);
241
242 kunmap_local(buf);
243 folio_end_read(folio, err == 0);
244 return err;
245}
246
247static struct vboxsf_handle *vboxsf_get_write_handle(struct vboxsf_inode *sf_i)
248{
249 struct vboxsf_handle *h, *sf_handle = NULL;
250
251 mutex_lock(&sf_i->handle_list_mutex);
252 list_for_each_entry(h, &sf_i->handle_list, head) {
253 if (h->access_flags == SHFL_CF_ACCESS_WRITE ||
254 h->access_flags == SHFL_CF_ACCESS_READWRITE) {
255 kref_get(&h->refcount);
256 sf_handle = h;
257 break;
258 }
259 }
260 mutex_unlock(&sf_i->handle_list_mutex);
261
262 return sf_handle;
263}
264
265static int vboxsf_writepage(struct page *page, struct writeback_control *wbc)
266{
267 struct inode *inode = page->mapping->host;
268 struct vboxsf_inode *sf_i = VBOXSF_I(inode);
269 struct vboxsf_handle *sf_handle;
270 loff_t off = page_offset(page);
271 loff_t size = i_size_read(inode);
272 u32 nwrite = PAGE_SIZE;
273 u8 *buf;
274 int err;
275
276 if (off + PAGE_SIZE > size)
277 nwrite = size & ~PAGE_MASK;
278
279 sf_handle = vboxsf_get_write_handle(sf_i);
280 if (!sf_handle)
281 return -EBADF;
282
283 buf = kmap(page);
284 err = vboxsf_write(sf_handle->root, sf_handle->handle,
285 off, &nwrite, buf);
286 kunmap(page);
287
288 kref_put(&sf_handle->refcount, vboxsf_handle_release);
289
290 if (err == 0) {
291 /* mtime changed */
292 sf_i->force_restat = 1;
293 } else {
294 ClearPageUptodate(page);
295 }
296
297 unlock_page(page);
298 return err;
299}
300
301static int vboxsf_write_end(struct file *file, struct address_space *mapping,
302 loff_t pos, unsigned int len, unsigned int copied,
303 struct folio *folio, void *fsdata)
304{
305 struct inode *inode = mapping->host;
306 struct vboxsf_handle *sf_handle = file->private_data;
307 size_t from = offset_in_folio(folio, pos);
308 u32 nwritten = len;
309 u8 *buf;
310 int err;
311
312 /* zero the stale part of the folio if we did a short copy */
313 if (!folio_test_uptodate(folio) && copied < len)
314 folio_zero_range(folio, from + copied, len - copied);
315
316 buf = kmap(&folio->page);
317 err = vboxsf_write(sf_handle->root, sf_handle->handle,
318 pos, &nwritten, buf + from);
319 kunmap(&folio->page);
320
321 if (err) {
322 nwritten = 0;
323 goto out;
324 }
325
326 /* mtime changed */
327 VBOXSF_I(inode)->force_restat = 1;
328
329 if (!folio_test_uptodate(folio) && nwritten == folio_size(folio))
330 folio_mark_uptodate(folio);
331
332 pos += nwritten;
333 if (pos > inode->i_size)
334 i_size_write(inode, pos);
335
336out:
337 folio_unlock(folio);
338 folio_put(folio);
339
340 return nwritten;
341}
342
343/*
344 * Note simple_write_begin does not read the page from disk on partial writes
345 * this is ok since vboxsf_write_end only writes the written parts of the
346 * page and it does not call folio_mark_uptodate for partial writes.
347 */
348const struct address_space_operations vboxsf_reg_aops = {
349 .read_folio = vboxsf_read_folio,
350 .writepage = vboxsf_writepage,
351 .dirty_folio = filemap_dirty_folio,
352 .write_begin = simple_write_begin,
353 .write_end = vboxsf_write_end,
354};
355
356static const char *vboxsf_get_link(struct dentry *dentry, struct inode *inode,
357 struct delayed_call *done)
358{
359 struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
360 struct shfl_string *path;
361 char *link;
362 int err;
363
364 if (!dentry)
365 return ERR_PTR(-ECHILD);
366
367 path = vboxsf_path_from_dentry(sbi, dentry);
368 if (IS_ERR(path))
369 return ERR_CAST(path);
370
371 link = kzalloc(PATH_MAX, GFP_KERNEL);
372 if (!link) {
373 __putname(path);
374 return ERR_PTR(-ENOMEM);
375 }
376
377 err = vboxsf_readlink(sbi->root, path, PATH_MAX, link);
378 __putname(path);
379 if (err) {
380 kfree(link);
381 return ERR_PTR(err);
382 }
383
384 set_delayed_call(done, kfree_link, link);
385 return link;
386}
387
388const struct inode_operations vboxsf_lnk_iops = {
389 .get_link = vboxsf_get_link
390};