vfs_addr.c 7.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * linux/fs/9p/vfs_addr.c
  4. *
  5. * This file contians vfs address (mmap) ops for 9P2000.
  6. *
  7. * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
  8. * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
  9. */
  10. #include <linux/module.h>
  11. #include <linux/errno.h>
  12. #include <linux/fs.h>
  13. #include <linux/file.h>
  14. #include <linux/stat.h>
  15. #include <linux/string.h>
  16. #include <linux/inet.h>
  17. #include <linux/pagemap.h>
  18. #include <linux/idr.h>
  19. #include <linux/sched.h>
  20. #include <linux/uio.h>
  21. #include <linux/bvec.h>
  22. #include <net/9p/9p.h>
  23. #include <net/9p/client.h>
  24. #include "v9fs.h"
  25. #include "v9fs_vfs.h"
  26. #include "cache.h"
  27. #include "fid.h"
  28. /**
  29. * v9fs_fid_readpage - read an entire page in from 9P
  30. *
  31. * @fid: fid being read
  32. * @page: structure to page
  33. *
  34. */
  35. static int v9fs_fid_readpage(void *data, struct page *page)
  36. {
  37. struct p9_fid *fid = data;
  38. struct inode *inode = page->mapping->host;
  39. struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
  40. struct iov_iter to;
  41. int retval, err;
  42. p9_debug(P9_DEBUG_VFS, "\n");
  43. BUG_ON(!PageLocked(page));
  44. retval = v9fs_readpage_from_fscache(inode, page);
  45. if (retval == 0)
  46. return retval;
  47. iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE);
  48. retval = p9_client_read(fid, page_offset(page), &to, &err);
  49. if (err) {
  50. v9fs_uncache_page(inode, page);
  51. retval = err;
  52. goto done;
  53. }
  54. zero_user(page, retval, PAGE_SIZE - retval);
  55. flush_dcache_page(page);
  56. SetPageUptodate(page);
  57. v9fs_readpage_to_fscache(inode, page);
  58. retval = 0;
  59. done:
  60. unlock_page(page);
  61. return retval;
  62. }
  63. /**
  64. * v9fs_vfs_readpage - read an entire page in from 9P
  65. *
  66. * @filp: file being read
  67. * @page: structure to page
  68. *
  69. */
  70. static int v9fs_vfs_readpage(struct file *filp, struct page *page)
  71. {
  72. return v9fs_fid_readpage(filp->private_data, page);
  73. }
  74. /**
  75. * v9fs_vfs_readpages - read a set of pages from 9P
  76. *
  77. * @filp: file being read
  78. * @mapping: the address space
  79. * @pages: list of pages to read
  80. * @nr_pages: count of pages to read
  81. *
  82. */
  83. static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
  84. struct list_head *pages, unsigned nr_pages)
  85. {
  86. int ret = 0;
  87. struct inode *inode;
  88. inode = mapping->host;
  89. p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
  90. ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
  91. if (ret == 0)
  92. return ret;
  93. ret = read_cache_pages(mapping, pages, v9fs_fid_readpage,
  94. filp->private_data);
  95. p9_debug(P9_DEBUG_VFS, " = %d\n", ret);
  96. return ret;
  97. }
  98. /**
  99. * v9fs_release_page - release the private state associated with a page
  100. *
  101. * Returns 1 if the page can be released, false otherwise.
  102. */
  103. static int v9fs_release_page(struct page *page, gfp_t gfp)
  104. {
  105. if (PagePrivate(page))
  106. return 0;
  107. return v9fs_fscache_release_page(page, gfp);
  108. }
  109. /**
  110. * v9fs_invalidate_page - Invalidate a page completely or partially
  111. *
  112. * @page: structure to page
  113. * @offset: offset in the page
  114. */
  115. static void v9fs_invalidate_page(struct page *page, unsigned int offset,
  116. unsigned int length)
  117. {
  118. /*
  119. * If called with zero offset, we should release
  120. * the private state assocated with the page
  121. */
  122. if (offset == 0 && length == PAGE_SIZE)
  123. v9fs_fscache_invalidate_page(page);
  124. }
  125. static int v9fs_vfs_writepage_locked(struct page *page)
  126. {
  127. struct inode *inode = page->mapping->host;
  128. struct v9fs_inode *v9inode = V9FS_I(inode);
  129. loff_t size = i_size_read(inode);
  130. struct iov_iter from;
  131. struct bio_vec bvec;
  132. int err, len;
  133. if (page->index == size >> PAGE_SHIFT)
  134. len = size & ~PAGE_MASK;
  135. else
  136. len = PAGE_SIZE;
  137. bvec.bv_page = page;
  138. bvec.bv_offset = 0;
  139. bvec.bv_len = len;
  140. iov_iter_bvec(&from, WRITE, &bvec, 1, len);
  141. /* We should have writeback_fid always set */
  142. BUG_ON(!v9inode->writeback_fid);
  143. set_page_writeback(page);
  144. p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);
  145. end_page_writeback(page);
  146. return err;
  147. }
  148. static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
  149. {
  150. int retval;
  151. p9_debug(P9_DEBUG_VFS, "page %p\n", page);
  152. retval = v9fs_vfs_writepage_locked(page);
  153. if (retval < 0) {
  154. if (retval == -EAGAIN) {
  155. redirty_page_for_writepage(wbc, page);
  156. retval = 0;
  157. } else {
  158. SetPageError(page);
  159. mapping_set_error(page->mapping, retval);
  160. }
  161. } else
  162. retval = 0;
  163. unlock_page(page);
  164. return retval;
  165. }
  166. /**
  167. * v9fs_launder_page - Writeback a dirty page
  168. * Returns 0 on success.
  169. */
  170. static int v9fs_launder_page(struct page *page)
  171. {
  172. int retval;
  173. struct inode *inode = page->mapping->host;
  174. v9fs_fscache_wait_on_page_write(inode, page);
  175. if (clear_page_dirty_for_io(page)) {
  176. retval = v9fs_vfs_writepage_locked(page);
  177. if (retval)
  178. return retval;
  179. }
  180. return 0;
  181. }
  182. /**
  183. * v9fs_direct_IO - 9P address space operation for direct I/O
  184. * @iocb: target I/O control block
  185. *
  186. * The presence of v9fs_direct_IO() in the address space ops vector
  187. * allowes open() O_DIRECT flags which would have failed otherwise.
  188. *
  189. * In the non-cached mode, we shunt off direct read and write requests before
  190. * the VFS gets them, so this method should never be called.
  191. *
  192. * Direct IO is not 'yet' supported in the cached mode. Hence when
  193. * this routine is called through generic_file_aio_read(), the read/write fails
  194. * with an error.
  195. *
  196. */
  197. static ssize_t
  198. v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
  199. {
  200. struct file *file = iocb->ki_filp;
  201. loff_t pos = iocb->ki_pos;
  202. ssize_t n;
  203. int err = 0;
  204. if (iov_iter_rw(iter) == WRITE) {
  205. n = p9_client_write(file->private_data, pos, iter, &err);
  206. if (n) {
  207. struct inode *inode = file_inode(file);
  208. loff_t i_size = i_size_read(inode);
  209. if (pos + n > i_size)
  210. inode_add_bytes(inode, pos + n - i_size);
  211. }
  212. } else {
  213. n = p9_client_read(file->private_data, pos, iter, &err);
  214. }
  215. return n ? n : err;
  216. }
  217. static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
  218. loff_t pos, unsigned len, unsigned flags,
  219. struct page **pagep, void **fsdata)
  220. {
  221. int retval = 0;
  222. struct page *page;
  223. struct v9fs_inode *v9inode;
  224. pgoff_t index = pos >> PAGE_SHIFT;
  225. struct inode *inode = mapping->host;
  226. p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
  227. v9inode = V9FS_I(inode);
  228. start:
  229. page = grab_cache_page_write_begin(mapping, index, flags);
  230. if (!page) {
  231. retval = -ENOMEM;
  232. goto out;
  233. }
  234. BUG_ON(!v9inode->writeback_fid);
  235. if (PageUptodate(page))
  236. goto out;
  237. if (len == PAGE_SIZE)
  238. goto out;
  239. retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
  240. put_page(page);
  241. if (!retval)
  242. goto start;
  243. out:
  244. *pagep = page;
  245. return retval;
  246. }
  247. static int v9fs_write_end(struct file *filp, struct address_space *mapping,
  248. loff_t pos, unsigned len, unsigned copied,
  249. struct page *page, void *fsdata)
  250. {
  251. loff_t last_pos = pos + copied;
  252. struct inode *inode = page->mapping->host;
  253. p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
  254. if (!PageUptodate(page)) {
  255. if (unlikely(copied < len)) {
  256. copied = 0;
  257. goto out;
  258. } else if (len == PAGE_SIZE) {
  259. SetPageUptodate(page);
  260. }
  261. }
  262. /*
  263. * No need to use i_size_read() here, the i_size
  264. * cannot change under us because we hold the i_mutex.
  265. */
  266. if (last_pos > inode->i_size) {
  267. inode_add_bytes(inode, last_pos - inode->i_size);
  268. i_size_write(inode, last_pos);
  269. }
  270. set_page_dirty(page);
  271. out:
  272. unlock_page(page);
  273. put_page(page);
  274. return copied;
  275. }
  276. const struct address_space_operations v9fs_addr_operations = {
  277. .readpage = v9fs_vfs_readpage,
  278. .readpages = v9fs_vfs_readpages,
  279. .set_page_dirty = __set_page_dirty_nobuffers,
  280. .writepage = v9fs_vfs_writepage,
  281. .write_begin = v9fs_write_begin,
  282. .write_end = v9fs_write_end,
  283. .releasepage = v9fs_release_page,
  284. .invalidatepage = v9fs_invalidate_page,
  285. .launder_page = v9fs_launder_page,
  286. .direct_IO = v9fs_direct_IO,
  287. };