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Linux/fs/nfs/file.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  *  linux/fs/nfs/file.c
  4  *
  5  *  Copyright (C) 1992  Rick Sladkey
  6  *
  7  *  Changes Copyright (C) 1994 by Florian La Roche
  8  *   - Do not copy data too often around in the kernel.
  9  *   - In nfs_file_read the return value of kmalloc wasn't checked.
 10  *   - Put in a better version of read look-ahead buffering. Original idea
 11  *     and implementation by Wai S Kok elekokws@ee.nus.sg.
 12  *
 13  *  Expire cache on write to a file by Wai S Kok (Oct 1994).
 14  *
 15  *  Total rewrite of read side for new NFS buffer cache.. Linus.
 16  *
 17  *  nfs regular file handling functions
 18  */
 19 
 20 #include <linux/module.h>
 21 #include <linux/time.h>
 22 #include <linux/kernel.h>
 23 #include <linux/errno.h>
 24 #include <linux/fcntl.h>
 25 #include <linux/stat.h>
 26 #include <linux/nfs_fs.h>
 27 #include <linux/nfs_mount.h>
 28 #include <linux/mm.h>
 29 #include <linux/pagemap.h>
 30 #include <linux/gfp.h>
 31 #include <linux/swap.h>
 32 
 33 #include <linux/uaccess.h>
 34 
 35 #include "delegation.h"
 36 #include "internal.h"
 37 #include "iostat.h"
 38 #include "fscache.h"
 39 #include "pnfs.h"
 40 
 41 #include "nfstrace.h"
 42 
 43 #define NFSDBG_FACILITY         NFSDBG_FILE
 44 
 45 static const struct vm_operations_struct nfs_file_vm_ops;
 46 
 47 /* Hack for future NFS swap support */
 48 #ifndef IS_SWAPFILE
 49 # define IS_SWAPFILE(inode)     (0)
 50 #endif
 51 
 52 int nfs_check_flags(int flags)
 53 {
 54         if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
 55                 return -EINVAL;
 56 
 57         return 0;
 58 }
 59 EXPORT_SYMBOL_GPL(nfs_check_flags);
 60 
 61 /*
 62  * Open file
 63  */
 64 static int
 65 nfs_file_open(struct inode *inode, struct file *filp)
 66 {
 67         int res;
 68 
 69         dprintk("NFS: open file(%pD2)\n", filp);
 70 
 71         nfs_inc_stats(inode, NFSIOS_VFSOPEN);
 72         res = nfs_check_flags(filp->f_flags);
 73         if (res)
 74                 return res;
 75 
 76         res = nfs_open(inode, filp);
 77         return res;
 78 }
 79 
 80 int
 81 nfs_file_release(struct inode *inode, struct file *filp)
 82 {
 83         dprintk("NFS: release(%pD2)\n", filp);
 84 
 85         nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
 86         nfs_file_clear_open_context(filp);
 87         return 0;
 88 }
 89 EXPORT_SYMBOL_GPL(nfs_file_release);
 90 
 91 /**
 92  * nfs_revalidate_size - Revalidate the file size
 93  * @inode: pointer to inode struct
 94  * @filp: pointer to struct file
 95  *
 96  * Revalidates the file length. This is basically a wrapper around
 97  * nfs_revalidate_inode() that takes into account the fact that we may
 98  * have cached writes (in which case we don't care about the server's
 99  * idea of what the file length is), or O_DIRECT (in which case we
100  * shouldn't trust the cache).
101  */
102 static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
103 {
104         struct nfs_server *server = NFS_SERVER(inode);
105 
106         if (filp->f_flags & O_DIRECT)
107                 goto force_reval;
108         if (nfs_check_cache_invalid(inode, NFS_INO_REVAL_PAGECACHE))
109                 goto force_reval;
110         return 0;
111 force_reval:
112         return __nfs_revalidate_inode(server, inode);
113 }
114 
115 loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
116 {
117         dprintk("NFS: llseek file(%pD2, %lld, %d)\n",
118                         filp, offset, whence);
119 
120         /*
121          * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
122          * the cached file length
123          */
124         if (whence != SEEK_SET && whence != SEEK_CUR) {
125                 struct inode *inode = filp->f_mapping->host;
126 
127                 int retval = nfs_revalidate_file_size(inode, filp);
128                 if (retval < 0)
129                         return (loff_t)retval;
130         }
131 
132         return generic_file_llseek(filp, offset, whence);
133 }
134 EXPORT_SYMBOL_GPL(nfs_file_llseek);
135 
136 /*
137  * Flush all dirty pages, and check for write errors.
138  */
139 static int
140 nfs_file_flush(struct file *file, fl_owner_t id)
141 {
142         struct inode    *inode = file_inode(file);
143 
144         dprintk("NFS: flush(%pD2)\n", file);
145 
146         nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
147         if ((file->f_mode & FMODE_WRITE) == 0)
148                 return 0;
149 
150         /* Flush writes to the server and return any errors */
151         return nfs_wb_all(inode);
152 }
153 
154 ssize_t
155 nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
156 {
157         struct inode *inode = file_inode(iocb->ki_filp);
158         ssize_t result;
159 
160         if (iocb->ki_flags & IOCB_DIRECT)
161                 return nfs_file_direct_read(iocb, to);
162 
163         dprintk("NFS: read(%pD2, %zu@%lu)\n",
164                 iocb->ki_filp,
165                 iov_iter_count(to), (unsigned long) iocb->ki_pos);
166 
167         nfs_start_io_read(inode);
168         result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
169         if (!result) {
170                 result = generic_file_read_iter(iocb, to);
171                 if (result > 0)
172                         nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
173         }
174         nfs_end_io_read(inode);
175         return result;
176 }
177 EXPORT_SYMBOL_GPL(nfs_file_read);
178 
179 int
180 nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
181 {
182         struct inode *inode = file_inode(file);
183         int     status;
184 
185         dprintk("NFS: mmap(%pD2)\n", file);
186 
187         /* Note: generic_file_mmap() returns ENOSYS on nommu systems
188          *       so we call that before revalidating the mapping
189          */
190         status = generic_file_mmap(file, vma);
191         if (!status) {
192                 vma->vm_ops = &nfs_file_vm_ops;
193                 status = nfs_revalidate_mapping(inode, file->f_mapping);
194         }
195         return status;
196 }
197 EXPORT_SYMBOL_GPL(nfs_file_mmap);
198 
199 /*
200  * Flush any dirty pages for this process, and check for write errors.
201  * The return status from this call provides a reliable indication of
202  * whether any write errors occurred for this process.
203  */
204 static int
205 nfs_file_fsync_commit(struct file *file, int datasync)
206 {
207         struct inode *inode = file_inode(file);
208         int ret;
209 
210         dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync);
211 
212         nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
213         ret = nfs_commit_inode(inode, FLUSH_SYNC);
214         if (ret < 0)
215                 return ret;
216         return file_check_and_advance_wb_err(file);
217 }
218 
219 int
220 nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
221 {
222         struct nfs_open_context *ctx = nfs_file_open_context(file);
223         struct inode *inode = file_inode(file);
224         int ret;
225 
226         trace_nfs_fsync_enter(inode);
227 
228         for (;;) {
229                 ret = file_write_and_wait_range(file, start, end);
230                 if (ret != 0)
231                         break;
232                 ret = nfs_file_fsync_commit(file, datasync);
233                 if (ret != 0)
234                         break;
235                 ret = pnfs_sync_inode(inode, !!datasync);
236                 if (ret != 0)
237                         break;
238                 if (!test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags))
239                         break;
240                 /*
241                  * If nfs_file_fsync_commit detected a server reboot, then
242                  * resend all dirty pages that might have been covered by
243                  * the NFS_CONTEXT_RESEND_WRITES flag
244                  */
245                 start = 0;
246                 end = LLONG_MAX;
247         }
248 
249         trace_nfs_fsync_exit(inode, ret);
250         return ret;
251 }
252 EXPORT_SYMBOL_GPL(nfs_file_fsync);
253 
254 /*
255  * Decide whether a read/modify/write cycle may be more efficient
256  * then a modify/write/read cycle when writing to a page in the
257  * page cache.
258  *
259  * Some pNFS layout drivers can only read/write at a certain block
260  * granularity like all block devices and therefore we must perform
261  * read/modify/write whenever a page hasn't read yet and the data
262  * to be written there is not aligned to a block boundary and/or
263  * smaller than the block size.
264  *
265  * The modify/write/read cycle may occur if a page is read before
266  * being completely filled by the writer.  In this situation, the
267  * page must be completely written to stable storage on the server
268  * before it can be refilled by reading in the page from the server.
269  * This can lead to expensive, small, FILE_SYNC mode writes being
270  * done.
271  *
272  * It may be more efficient to read the page first if the file is
273  * open for reading in addition to writing, the page is not marked
274  * as Uptodate, it is not dirty or waiting to be committed,
275  * indicating that it was previously allocated and then modified,
276  * that there were valid bytes of data in that range of the file,
277  * and that the new data won't completely replace the old data in
278  * that range of the file.
279  */
280 static bool nfs_full_page_write(struct page *page, loff_t pos, unsigned int len)
281 {
282         unsigned int pglen = nfs_page_length(page);
283         unsigned int offset = pos & (PAGE_SIZE - 1);
284         unsigned int end = offset + len;
285 
286         return !pglen || (end >= pglen && !offset);
287 }
288 
289 static bool nfs_want_read_modify_write(struct file *file, struct page *page,
290                         loff_t pos, unsigned int len)
291 {
292         /*
293          * Up-to-date pages, those with ongoing or full-page write
294          * don't need read/modify/write
295          */
296         if (PageUptodate(page) || PagePrivate(page) ||
297             nfs_full_page_write(page, pos, len))
298                 return false;
299 
300         if (pnfs_ld_read_whole_page(file->f_mapping->host))
301                 return true;
302         /* Open for reading too? */
303         if (file->f_mode & FMODE_READ)
304                 return true;
305         return false;
306 }
307 
308 /*
309  * This does the "real" work of the write. We must allocate and lock the
310  * page to be sent back to the generic routine, which then copies the
311  * data from user space.
312  *
313  * If the writer ends up delaying the write, the writer needs to
314  * increment the page use counts until he is done with the page.
315  */
316 static int nfs_write_begin(struct file *file, struct address_space *mapping,
317                         loff_t pos, unsigned len, unsigned flags,
318                         struct page **pagep, void **fsdata)
319 {
320         int ret;
321         pgoff_t index = pos >> PAGE_SHIFT;
322         struct page *page;
323         int once_thru = 0;
324 
325         dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)\n",
326                 file, mapping->host->i_ino, len, (long long) pos);
327 
328 start:
329         page = grab_cache_page_write_begin(mapping, index, flags);
330         if (!page)
331                 return -ENOMEM;
332         *pagep = page;
333 
334         ret = nfs_flush_incompatible(file, page);
335         if (ret) {
336                 unlock_page(page);
337                 put_page(page);
338         } else if (!once_thru &&
339                    nfs_want_read_modify_write(file, page, pos, len)) {
340                 once_thru = 1;
341                 ret = nfs_readpage(file, page);
342                 put_page(page);
343                 if (!ret)
344                         goto start;
345         }
346         return ret;
347 }
348 
349 static int nfs_write_end(struct file *file, struct address_space *mapping,
350                         loff_t pos, unsigned len, unsigned copied,
351                         struct page *page, void *fsdata)
352 {
353         unsigned offset = pos & (PAGE_SIZE - 1);
354         struct nfs_open_context *ctx = nfs_file_open_context(file);
355         int status;
356 
357         dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)\n",
358                 file, mapping->host->i_ino, len, (long long) pos);
359 
360         /*
361          * Zero any uninitialised parts of the page, and then mark the page
362          * as up to date if it turns out that we're extending the file.
363          */
364         if (!PageUptodate(page)) {
365                 unsigned pglen = nfs_page_length(page);
366                 unsigned end = offset + copied;
367 
368                 if (pglen == 0) {
369                         zero_user_segments(page, 0, offset,
370                                         end, PAGE_SIZE);
371                         SetPageUptodate(page);
372                 } else if (end >= pglen) {
373                         zero_user_segment(page, end, PAGE_SIZE);
374                         if (offset == 0)
375                                 SetPageUptodate(page);
376                 } else
377                         zero_user_segment(page, pglen, PAGE_SIZE);
378         }
379 
380         status = nfs_updatepage(file, page, offset, copied);
381 
382         unlock_page(page);
383         put_page(page);
384 
385         if (status < 0)
386                 return status;
387         NFS_I(mapping->host)->write_io += copied;
388 
389         if (nfs_ctx_key_to_expire(ctx, mapping->host)) {
390                 status = nfs_wb_all(mapping->host);
391                 if (status < 0)
392                         return status;
393         }
394 
395         return copied;
396 }
397 
398 /*
399  * Partially or wholly invalidate a page
400  * - Release the private state associated with a page if undergoing complete
401  *   page invalidation
402  * - Called if either PG_private or PG_fscache is set on the page
403  * - Caller holds page lock
404  */
405 static void nfs_invalidate_page(struct page *page, unsigned int offset,
406                                 unsigned int length)
407 {
408         dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)\n",
409                  page, offset, length);
410 
411         if (offset != 0 || length < PAGE_SIZE)
412                 return;
413         /* Cancel any unstarted writes on this page */
414         nfs_wb_page_cancel(page_file_mapping(page)->host, page);
415 
416         nfs_fscache_invalidate_page(page, page->mapping->host);
417 }
418 
419 /*
420  * Attempt to release the private state associated with a page
421  * - Called if either PG_private or PG_fscache is set on the page
422  * - Caller holds page lock
423  * - Return true (may release page) or false (may not)
424  */
425 static int nfs_release_page(struct page *page, gfp_t gfp)
426 {
427         dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
428 
429         /* If PagePrivate() is set, then the page is not freeable */
430         if (PagePrivate(page))
431                 return 0;
432         return nfs_fscache_release_page(page, gfp);
433 }
434 
435 static void nfs_check_dirty_writeback(struct page *page,
436                                 bool *dirty, bool *writeback)
437 {
438         struct nfs_inode *nfsi;
439         struct address_space *mapping = page_file_mapping(page);
440 
441         if (!mapping || PageSwapCache(page))
442                 return;
443 
444         /*
445          * Check if an unstable page is currently being committed and
446          * if so, have the VM treat it as if the page is under writeback
447          * so it will not block due to pages that will shortly be freeable.
448          */
449         nfsi = NFS_I(mapping->host);
450         if (atomic_read(&nfsi->commit_info.rpcs_out)) {
451                 *writeback = true;
452                 return;
453         }
454 
455         /*
456          * If PagePrivate() is set, then the page is not freeable and as the
457          * inode is not being committed, it's not going to be cleaned in the
458          * near future so treat it as dirty
459          */
460         if (PagePrivate(page))
461                 *dirty = true;
462 }
463 
464 /*
465  * Attempt to clear the private state associated with a page when an error
466  * occurs that requires the cached contents of an inode to be written back or
467  * destroyed
468  * - Called if either PG_private or fscache is set on the page
469  * - Caller holds page lock
470  * - Return 0 if successful, -error otherwise
471  */
472 static int nfs_launder_page(struct page *page)
473 {
474         struct inode *inode = page_file_mapping(page)->host;
475         struct nfs_inode *nfsi = NFS_I(inode);
476 
477         dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
478                 inode->i_ino, (long long)page_offset(page));
479 
480         nfs_fscache_wait_on_page_write(nfsi, page);
481         return nfs_wb_page(inode, page);
482 }
483 
484 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
485                                                 sector_t *span)
486 {
487         unsigned long blocks;
488         long long isize;
489         struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
490         struct inode *inode = file->f_mapping->host;
491 
492         spin_lock(&inode->i_lock);
493         blocks = inode->i_blocks;
494         isize = inode->i_size;
495         spin_unlock(&inode->i_lock);
496         if (blocks*512 < isize) {
497                 pr_warn("swap activate: swapfile has holes\n");
498                 return -EINVAL;
499         }
500 
501         *span = sis->pages;
502 
503         return rpc_clnt_swap_activate(clnt);
504 }
505 
506 static void nfs_swap_deactivate(struct file *file)
507 {
508         struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
509 
510         rpc_clnt_swap_deactivate(clnt);
511 }
512 
513 const struct address_space_operations nfs_file_aops = {
514         .readpage = nfs_readpage,
515         .readpages = nfs_readpages,
516         .set_page_dirty = __set_page_dirty_nobuffers,
517         .writepage = nfs_writepage,
518         .writepages = nfs_writepages,
519         .write_begin = nfs_write_begin,
520         .write_end = nfs_write_end,
521         .invalidatepage = nfs_invalidate_page,
522         .releasepage = nfs_release_page,
523         .direct_IO = nfs_direct_IO,
524 #ifdef CONFIG_MIGRATION
525         .migratepage = nfs_migrate_page,
526 #endif
527         .launder_page = nfs_launder_page,
528         .is_dirty_writeback = nfs_check_dirty_writeback,
529         .error_remove_page = generic_error_remove_page,
530         .swap_activate = nfs_swap_activate,
531         .swap_deactivate = nfs_swap_deactivate,
532 };
533 
534 /*
535  * Notification that a PTE pointing to an NFS page is about to be made
536  * writable, implying that someone is about to modify the page through a
537  * shared-writable mapping
538  */
539 static vm_fault_t nfs_vm_page_mkwrite(struct vm_fault *vmf)
540 {
541         struct page *page = vmf->page;
542         struct file *filp = vmf->vma->vm_file;
543         struct inode *inode = file_inode(filp);
544         unsigned pagelen;
545         vm_fault_t ret = VM_FAULT_NOPAGE;
546         struct address_space *mapping;
547 
548         dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n",
549                 filp, filp->f_mapping->host->i_ino,
550                 (long long)page_offset(page));
551 
552         sb_start_pagefault(inode->i_sb);
553 
554         /* make sure the cache has finished storing the page */
555         nfs_fscache_wait_on_page_write(NFS_I(inode), page);
556 
557         wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
558                         nfs_wait_bit_killable, TASK_KILLABLE);
559 
560         lock_page(page);
561         mapping = page_file_mapping(page);
562         if (mapping != inode->i_mapping)
563                 goto out_unlock;
564 
565         wait_on_page_writeback(page);
566 
567         pagelen = nfs_page_length(page);
568         if (pagelen == 0)
569                 goto out_unlock;
570 
571         ret = VM_FAULT_LOCKED;
572         if (nfs_flush_incompatible(filp, page) == 0 &&
573             nfs_updatepage(filp, page, 0, pagelen) == 0)
574                 goto out;
575 
576         ret = VM_FAULT_SIGBUS;
577 out_unlock:
578         unlock_page(page);
579 out:
580         sb_end_pagefault(inode->i_sb);
581         return ret;
582 }
583 
584 static const struct vm_operations_struct nfs_file_vm_ops = {
585         .fault = filemap_fault,
586         .map_pages = filemap_map_pages,
587         .page_mkwrite = nfs_vm_page_mkwrite,
588 };
589 
590 static int nfs_need_check_write(struct file *filp, struct inode *inode)
591 {
592         struct nfs_open_context *ctx;
593 
594         ctx = nfs_file_open_context(filp);
595         if (nfs_ctx_key_to_expire(ctx, inode))
596                 return 1;
597         return 0;
598 }
599 
600 ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
601 {
602         struct file *file = iocb->ki_filp;
603         struct inode *inode = file_inode(file);
604         unsigned long written = 0;
605         ssize_t result;
606 
607         result = nfs_key_timeout_notify(file, inode);
608         if (result)
609                 return result;
610 
611         if (iocb->ki_flags & IOCB_DIRECT)
612                 return nfs_file_direct_write(iocb, from);
613 
614         dprintk("NFS: write(%pD2, %zu@%Ld)\n",
615                 file, iov_iter_count(from), (long long) iocb->ki_pos);
616 
617         if (IS_SWAPFILE(inode))
618                 goto out_swapfile;
619         /*
620          * O_APPEND implies that we must revalidate the file length.
621          */
622         if (iocb->ki_flags & IOCB_APPEND) {
623                 result = nfs_revalidate_file_size(inode, file);
624                 if (result)
625                         goto out;
626         }
627         if (iocb->ki_pos > i_size_read(inode))
628                 nfs_revalidate_mapping(inode, file->f_mapping);
629 
630         nfs_start_io_write(inode);
631         result = generic_write_checks(iocb, from);
632         if (result > 0) {
633                 current->backing_dev_info = inode_to_bdi(inode);
634                 result = generic_perform_write(file, from, iocb->ki_pos);
635                 current->backing_dev_info = NULL;
636         }
637         nfs_end_io_write(inode);
638         if (result <= 0)
639                 goto out;
640 
641         written = result;
642         iocb->ki_pos += written;
643         result = generic_write_sync(iocb, written);
644         if (result < 0)
645                 goto out;
646 
647         /* Return error values */
648         if (nfs_need_check_write(file, inode)) {
649                 int err = nfs_wb_all(inode);
650                 if (err < 0)
651                         result = err;
652         }
653         nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
654 out:
655         return result;
656 
657 out_swapfile:
658         printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
659         return -ETXTBSY;
660 }
661 EXPORT_SYMBOL_GPL(nfs_file_write);
662 
663 static int
664 do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
665 {
666         struct inode *inode = filp->f_mapping->host;
667         int status = 0;
668         unsigned int saved_type = fl->fl_type;
669 
670         /* Try local locking first */
671         posix_test_lock(filp, fl);
672         if (fl->fl_type != F_UNLCK) {
673                 /* found a conflict */
674                 goto out;
675         }
676         fl->fl_type = saved_type;
677 
678         if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
679                 goto out_noconflict;
680 
681         if (is_local)
682                 goto out_noconflict;
683 
684         status = NFS_PROTO(inode)->lock(filp, cmd, fl);
685 out:
686         return status;
687 out_noconflict:
688         fl->fl_type = F_UNLCK;
689         goto out;
690 }
691 
692 static int
693 do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
694 {
695         struct inode *inode = filp->f_mapping->host;
696         struct nfs_lock_context *l_ctx;
697         int status;
698 
699         /*
700          * Flush all pending writes before doing anything
701          * with locks..
702          */
703         nfs_wb_all(inode);
704 
705         l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
706         if (!IS_ERR(l_ctx)) {
707                 status = nfs_iocounter_wait(l_ctx);
708                 nfs_put_lock_context(l_ctx);
709                 /*  NOTE: special case
710                  *      If we're signalled while cleaning up locks on process exit, we
711                  *      still need to complete the unlock.
712                  */
713                 if (status < 0 && !(fl->fl_flags & FL_CLOSE))
714                         return status;
715         }
716 
717         /*
718          * Use local locking if mounted with "-onolock" or with appropriate
719          * "-olocal_lock="
720          */
721         if (!is_local)
722                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
723         else
724                 status = locks_lock_file_wait(filp, fl);
725         return status;
726 }
727 
728 static int
729 do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
730 {
731         struct inode *inode = filp->f_mapping->host;
732         int status;
733 
734         /*
735          * Flush all pending writes before doing anything
736          * with locks..
737          */
738         status = nfs_sync_mapping(filp->f_mapping);
739         if (status != 0)
740                 goto out;
741 
742         /*
743          * Use local locking if mounted with "-onolock" or with appropriate
744          * "-olocal_lock="
745          */
746         if (!is_local)
747                 status = NFS_PROTO(inode)->lock(filp, cmd, fl);
748         else
749                 status = locks_lock_file_wait(filp, fl);
750         if (status < 0)
751                 goto out;
752 
753         /*
754          * Invalidate cache to prevent missing any changes.  If
755          * the file is mapped, clear the page cache as well so
756          * those mappings will be loaded.
757          *
758          * This makes locking act as a cache coherency point.
759          */
760         nfs_sync_mapping(filp->f_mapping);
761         if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {
762                 nfs_zap_caches(inode);
763                 if (mapping_mapped(filp->f_mapping))
764                         nfs_revalidate_mapping(inode, filp->f_mapping);
765         }
766 out:
767         return status;
768 }
769 
770 /*
771  * Lock a (portion of) a file
772  */
773 int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
774 {
775         struct inode *inode = filp->f_mapping->host;
776         int ret = -ENOLCK;
777         int is_local = 0;
778 
779         dprintk("NFS: lock(%pD2, t=%x, fl=%x, r=%lld:%lld)\n",
780                         filp, fl->fl_type, fl->fl_flags,
781                         (long long)fl->fl_start, (long long)fl->fl_end);
782 
783         nfs_inc_stats(inode, NFSIOS_VFSLOCK);
784 
785         /* No mandatory locks over NFS */
786         if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
787                 goto out_err;
788 
789         if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
790                 is_local = 1;
791 
792         if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
793                 ret = NFS_PROTO(inode)->lock_check_bounds(fl);
794                 if (ret < 0)
795                         goto out_err;
796         }
797 
798         if (IS_GETLK(cmd))
799                 ret = do_getlk(filp, cmd, fl, is_local);
800         else if (fl->fl_type == F_UNLCK)
801                 ret = do_unlk(filp, cmd, fl, is_local);
802         else
803                 ret = do_setlk(filp, cmd, fl, is_local);
804 out_err:
805         return ret;
806 }
807 EXPORT_SYMBOL_GPL(nfs_lock);
808 
809 /*
810  * Lock a (portion of) a file
811  */
812 int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
813 {
814         struct inode *inode = filp->f_mapping->host;
815         int is_local = 0;
816 
817         dprintk("NFS: flock(%pD2, t=%x, fl=%x)\n",
818                         filp, fl->fl_type, fl->fl_flags);
819 
820         if (!(fl->fl_flags & FL_FLOCK))
821                 return -ENOLCK;
822 
823         /*
824          * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
825          * any standard. In principle we might be able to support LOCK_MAND
826          * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
827          * NFS code is not set up for it.
828          */
829         if (fl->fl_type & LOCK_MAND)
830                 return -EINVAL;
831 
832         if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
833                 is_local = 1;
834 
835         /* We're simulating flock() locks using posix locks on the server */
836         if (fl->fl_type == F_UNLCK)
837                 return do_unlk(filp, cmd, fl, is_local);
838         return do_setlk(filp, cmd, fl, is_local);
839 }
840 EXPORT_SYMBOL_GPL(nfs_flock);
841 
842 const struct file_operations nfs_file_operations = {
843         .llseek         = nfs_file_llseek,
844         .read_iter      = nfs_file_read,
845         .write_iter     = nfs_file_write,
846         .mmap           = nfs_file_mmap,
847         .open           = nfs_file_open,
848         .flush          = nfs_file_flush,
849         .release        = nfs_file_release,
850         .fsync          = nfs_file_fsync,
851         .lock           = nfs_lock,
852         .flock          = nfs_flock,
853         .splice_read    = generic_file_splice_read,
854         .splice_write   = iter_file_splice_write,
855         .check_flags    = nfs_check_flags,
856         .setlease       = simple_nosetlease,
857 };
858 EXPORT_SYMBOL_GPL(nfs_file_operations);
859 

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