1	// SPDX-License-Identifier: GPL-2.0
2	/*
3	* File operations used by nfsd. Some of these have been ripped from
4	* other parts of the kernel because they weren't exported, others
5	* are partial duplicates with added or changed functionality.
6	*
7	* Note that several functions dget() the dentry upon which they want
8	* to act, most notably those that create directory entries. Response
9	* dentry's are dput()'d if necessary in the release callback.
10	* So if you notice code paths that apparently fail to dput() the
11	* dentry, don't worry--they have been taken care of.
12	*
13	* Copyright (C) 1995-1999 Olaf Kirch <okir@monad.swb.de>
14	* Zerocpy NFS support (C) 2002 Hirokazu Takahashi <taka@valinux.co.jp>
15	*/
16
17	#include <linux/fs.h>
18	#include <linux/file.h>
19	#include <linux/splice.h>
20	#include <linux/falloc.h>
21	#include <linux/fcntl.h>
22	#include <linux/namei.h>
23	#include <linux/delay.h>
24	#include <linux/fsnotify.h>
25	#include <linux/posix_acl_xattr.h>
26	#include <linux/xattr.h>
27	#include <linux/jhash.h>
28	#include <linux/pagemap.h>
29	#include <linux/slab.h>
30	#include <linux/uaccess.h>
31	#include <linux/exportfs.h>
32	#include <linux/writeback.h>
33	#include <linux/security.h>
34
35	#include "xdr3.h"
36
37	#ifdef CONFIG_NFSD_V4
38	#include "../internal.h"
39	#include "acl.h"
40	#include "idmap.h"
41	#include "xdr4.h"
42	#endif /* CONFIG_NFSD_V4 */
43
44	#include "nfsd.h"
45	#include "vfs.h"
46	#include "filecache.h"
47	#include "trace.h"
48
49	#define NFSDDBG_FACILITY NFSDDBG_FILEOP
50
51	/**
52	* nfserrno - Map Linux errnos to NFS errnos
53	* @errno: POSIX(-ish) error code to be mapped
54	*
55	* Returns the appropriate (net-endian) nfserr_* (or nfs_ok if errno is 0). If
56	* it's an error we don't expect, log it once and return nfserr_io.
57	*/
58	__be32
59	nfserrno (int errno)
60	{
61	static struct {
62	__be32 nfserr;
63	int syserr;
64	} nfs_errtbl[] = {
65	{ nfs_ok, 0 },
66	{ nfserr_perm, -EPERM },
67	{ nfserr_noent, -ENOENT },
68	{ nfserr_io, -EIO },
69	{ nfserr_nxio, -ENXIO },
70	{ nfserr_fbig, -E2BIG },
71	{ nfserr_stale, -EBADF },
72	{ nfserr_acces, -EACCES },
73	{ nfserr_exist, -EEXIST },
74	{ nfserr_xdev, -EXDEV },
75	{ nfserr_mlink, -EMLINK },
76	{ nfserr_nodev, -ENODEV },
77	{ nfserr_notdir, -ENOTDIR },
78	{ nfserr_isdir, -EISDIR },
79	{ nfserr_inval, -EINVAL },
80	{ nfserr_fbig, -EFBIG },
81	{ nfserr_nospc, -ENOSPC },
82	{ nfserr_rofs, -EROFS },
83	{ nfserr_mlink, -EMLINK },
84	{ nfserr_nametoolong, -ENAMETOOLONG },
85	{ nfserr_notempty, -ENOTEMPTY },
86	{ nfserr_dquot, -EDQUOT },
87	{ nfserr_stale, -ESTALE },
88	{ nfserr_jukebox, -ETIMEDOUT },
89	{ nfserr_jukebox, -ERESTARTSYS },
90	{ nfserr_jukebox, -EAGAIN },
91	{ nfserr_jukebox, -EWOULDBLOCK },
92	{ nfserr_jukebox, -ENOMEM },
93	{ nfserr_io, -ETXTBSY },
94	{ nfserr_notsupp, -EOPNOTSUPP },
95	{ nfserr_toosmall, -ETOOSMALL },
96	{ nfserr_serverfault, -ESERVERFAULT },
97	{ nfserr_serverfault, -ENFILE },
98	{ nfserr_io, -EREMOTEIO },
99	{ nfserr_stale, -EOPENSTALE },
100	{ nfserr_io, -EUCLEAN },
101	{ nfserr_perm, -ENOKEY },
102	{ nfserr_no_grace, -ENOGRACE},
103	};
104	int i;
105
106	for (i = 0; i < ARRAY_SIZE(nfs_errtbl); i++) {
107	if (nfs_errtbl[i].syserr == errno)
108	return nfs_errtbl[i].nfserr;
109	}
110	WARN_ONCE(1, "nfsd: non-standard errno: %d\n", errno);
111	return nfserr_io;
112	}
113
114	/*
115	* Called from nfsd_lookup and encode_dirent. Check if we have crossed
116	* a mount point.
117	* Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
118	* or nfs_ok having possibly changed *dpp and *expp
119	*/
120	int
121	nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
122	struct svc_export **expp)
123	{
124	struct svc_export *exp = *expp, *exp2 = NULL;
125	struct dentry *dentry = *dpp;
126	struct path path = {.mnt = mntget(mnt: exp->ex_path.mnt),
127	.dentry = dget(dentry)};
128	unsigned int follow_flags = 0;
129	int err = 0;
130
131	if (exp->ex_flags & NFSEXP_CROSSMOUNT)
132	follow_flags = LOOKUP_AUTOMOUNT;
133
134	err = follow_down(path: &path, flags: follow_flags);
135	if (err < 0)
136	goto out;
137	if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
138	nfsd_mountpoint(dentry, exp) == 2) {
139	/* This is only a mountpoint in some other namespace */
140	path_put(&path);
141	goto out;
142	}
143
144	exp2 = rqst_exp_get_by_name(rqstp, &path);
145	if (IS_ERR(ptr: exp2)) {
146	err = PTR_ERR(ptr: exp2);
147	/*
148	* We normally allow NFS clients to continue
149	* "underneath" a mountpoint that is not exported.
150	* The exception is V4ROOT, where no traversal is ever
151	* allowed without an explicit export of the new
152	* directory.
153	*/
154	if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
155	err = 0;
156	path_put(&path);
157	goto out;
158	}
159	if (nfsd_v4client(rq: rqstp) ||
160	(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
161	/* successfully crossed mount point */
162	/*
163	* This is subtle: path.dentry is *not* on path.mnt
164	* at this point. The only reason we are safe is that
165	* original mnt is pinned down by exp, so we should
166	* put path *before* putting exp
167	*/
168	*dpp = path.dentry;
169	path.dentry = dentry;
170	*expp = exp2;
171	exp2 = exp;
172	}
173	path_put(&path);
174	exp_put(exp: exp2);
175	out:
176	return err;
177	}
178
179	static void follow_to_parent(struct path *path)
180	{
181	struct dentry *dp;
182
183	while (path->dentry == path->mnt->mnt_root && follow_up(path))
184	;
185	dp = dget_parent(dentry: path->dentry);
186	dput(path->dentry);
187	path->dentry = dp;
188	}
189
190	static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
191	{
192	struct svc_export *exp2;
193	struct path path = {.mnt = mntget(mnt: (*exp)->ex_path.mnt),
194	.dentry = dget(dentry: dparent)};
195
196	follow_to_parent(path: &path);
197
198	exp2 = rqst_exp_parent(rqstp, &path);
199	if (PTR_ERR(ptr: exp2) == -ENOENT) {
200	*dentryp = dget(dentry: dparent);
201	} else if (IS_ERR(ptr: exp2)) {
202	path_put(&path);
203	return PTR_ERR(ptr: exp2);
204	} else {
205	*dentryp = dget(dentry: path.dentry);
206	exp_put(exp: *exp);
207	*exp = exp2;
208	}
209	path_put(&path);
210	return 0;
211	}
212
213	/*
214	* For nfsd purposes, we treat V4ROOT exports as though there was an
215	* export at *every* directory.
216	* We return:
217	* '1' if this dentry *must* be an export point,
218	* '2' if it might be, if there is really a mount here, and
219	* '0' if there is no chance of an export point here.
220	*/
221	int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
222	{
223	if (!d_inode(dentry))
224	return 0;
225	if (exp->ex_flags & NFSEXP_V4ROOT)
226	return 1;
227	if (nfsd4_is_junction(dentry))
228	return 1;
229	if (d_managed(dentry))
230	/*
231	* Might only be a mountpoint in a different namespace,
232	* but we need to check.
233	*/
234	return 2;
235	return 0;
236	}
237
238	__be32
239	nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
240	const char *name, unsigned int len,
241	struct svc_export **exp_ret, struct dentry **dentry_ret)
242	{
243	struct svc_export *exp;
244	struct dentry *dparent;
245	struct dentry *dentry;
246	int host_err;
247
248	dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
249
250	dparent = fhp->fh_dentry;
251	exp = exp_get(exp: fhp->fh_export);
252
253	/* Lookup the name, but don't follow links */
254	if (isdotent(name, len)) {
255	if (len==1)
256	dentry = dget(dentry: dparent);
257	else if (dparent != exp->ex_path.dentry)
258	dentry = dget_parent(dentry: dparent);
259	else if (!EX_NOHIDE(exp) && !nfsd_v4client(rq: rqstp))
260	dentry = dget(dentry: dparent); /* .. == . just like at / */
261	else {
262	/* checking mountpoint crossing is very different when stepping up */
263	host_err = nfsd_lookup_parent(rqstp, dparent, exp: &exp, dentryp: &dentry);
264	if (host_err)
265	goto out_nfserr;
266	}
267	} else {
268	dentry = lookup_one_len_unlocked(name, dparent, len);
269	host_err = PTR_ERR(ptr: dentry);
270	if (IS_ERR(ptr: dentry))
271	goto out_nfserr;
272	if (nfsd_mountpoint(dentry, exp)) {
273	host_err = nfsd_cross_mnt(rqstp, dpp: &dentry, expp: &exp);
274	if (host_err) {
275	dput(dentry);
276	goto out_nfserr;
277	}
278	}
279	}
280	*dentry_ret = dentry;
281	*exp_ret = exp;
282	return 0;
283
284	out_nfserr:
285	exp_put(exp);
286	return nfserrno(errno: host_err);
287	}
288
289	/**
290	* nfsd_lookup - look up a single path component for nfsd
291	*
292	* @rqstp: the request context
293	* @fhp: the file handle of the directory
294	* @name: the component name, or %NULL to look up parent
295	* @len: length of name to examine
296	* @resfh: pointer to pre-initialised filehandle to hold result.
297	*
298	* Look up one component of a pathname.
299	* N.B. After this call _both_ fhp and resfh need an fh_put
300	*
301	* If the lookup would cross a mountpoint, and the mounted filesystem
302	* is exported to the client with NFSEXP_NOHIDE, then the lookup is
303	* accepted as it stands and the mounted directory is
304	* returned. Otherwise the covered directory is returned.
305	* NOTE: this mountpoint crossing is not supported properly by all
306	* clients and is explicitly disallowed for NFSv3
307	*
308	*/
309	__be32
310	nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
311	unsigned int len, struct svc_fh *resfh)
312	{
313	struct svc_export *exp;
314	struct dentry *dentry;
315	__be32 err;
316
317	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
318	if (err)
319	return err;
320	err = nfsd_lookup_dentry(rqstp, fhp, name, len, exp_ret: &exp, dentry_ret: &dentry);
321	if (err)
322	return err;
323	err = check_nfsd_access(exp, rqstp);
324	if (err)
325	goto out;
326	/*
327	* Note: we compose the file handle now, but as the
328	* dentry may be negative, it may need to be updated.
329	*/
330	err = fh_compose(resfh, exp, dentry, fhp);
331	if (!err && d_really_is_negative(dentry))
332	err = nfserr_noent;
333	out:
334	dput(dentry);
335	exp_put(exp);
336	return err;
337	}
338
339	static void
340	commit_reset_write_verifier(struct nfsd_net *nn, struct svc_rqst *rqstp,
341	int err)
342	{
343	switch (err) {
344	case -EAGAIN:
345	case -ESTALE:
346	/*
347	* Neither of these are the result of a problem with
348	* durable storage, so avoid a write verifier reset.
349	*/
350	break;
351	default:
352	nfsd_reset_write_verifier(nn);
353	trace_nfsd_writeverf_reset(nn, rqstp, error: err);
354	}
355	}
356
357	/*
358	* Commit metadata changes to stable storage.
359	*/
360	static int
361	commit_inode_metadata(struct inode *inode)
362	{
363	const struct export_operations *export_ops = inode->i_sb->s_export_op;
364
365	if (export_ops->commit_metadata)
366	return export_ops->commit_metadata(inode);
367	return sync_inode_metadata(inode, wait: 1);
368	}
369
370	static int
371	commit_metadata(struct svc_fh *fhp)
372	{
373	struct inode *inode = d_inode(dentry: fhp->fh_dentry);
374
375	if (!EX_ISSYNC(fhp->fh_export))
376	return 0;
377	return commit_inode_metadata(inode);
378	}
379
380	/*
381	* Go over the attributes and take care of the small differences between
382	* NFS semantics and what Linux expects.
383	*/
384	static void
385	nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
386	{
387	/* Ignore mode updates on symlinks */
388	if (S_ISLNK(inode->i_mode))
389	iap->ia_valid &= ~ATTR_MODE;
390
391	/* sanitize the mode change */
392	if (iap->ia_valid & ATTR_MODE) {
393	iap->ia_mode &= S_IALLUGO;
394	iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
395	}
396
397	/* Revoke setuid/setgid on chown */
398	if (!S_ISDIR(inode->i_mode) &&
399	((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
400	iap->ia_valid |= ATTR_KILL_PRIV;
401	if (iap->ia_valid & ATTR_MODE) {
402	/* we're setting mode too, just clear the s*id bits */
403	iap->ia_mode &= ~S_ISUID;
404	if (iap->ia_mode & S_IXGRP)
405	iap->ia_mode &= ~S_ISGID;
406	} else {
407	/* set ATTR_KILL_* bits and let VFS handle it */
408	iap->ia_valid |= ATTR_KILL_SUID;
409	iap->ia_valid |=
410	setattr_should_drop_sgid(idmap: &nop_mnt_idmap, inode);
411	}
412	}
413	}
414
415	static __be32
416	nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
417	struct iattr *iap)
418	{
419	struct inode *inode = d_inode(dentry: fhp->fh_dentry);
420
421	if (iap->ia_size < inode->i_size) {
422	__be32 err;
423
424	err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
425	NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
426	if (err)
427	return err;
428	}
429	return nfserrno(errno: get_write_access(inode));
430	}
431
432	static int __nfsd_setattr(struct dentry *dentry, struct iattr *iap)
433	{
434	int host_err;
435
436	if (iap->ia_valid & ATTR_SIZE) {
437	/*
438	* RFC5661, Section 18.30.4:
439	* Changing the size of a file with SETATTR indirectly
440	* changes the time_modify and change attributes.
441	*
442	* (and similar for the older RFCs)
443	*/
444	struct iattr size_attr = {
445	.ia_valid = ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
446	.ia_size = iap->ia_size,
447	};
448
449	if (iap->ia_size < 0)
450	return -EFBIG;
451
452	host_err = notify_change(&nop_mnt_idmap, dentry, &size_attr, NULL);
453	if (host_err)
454	return host_err;
455	iap->ia_valid &= ~ATTR_SIZE;
456
457	/*
458	* Avoid the additional setattr call below if the only other
459	* attribute that the client sends is the mtime, as we update
460	* it as part of the size change above.
461	*/
462	if ((iap->ia_valid & ~ATTR_MTIME) == 0)
463	return 0;
464	}
465
466	if (!iap->ia_valid)
467	return 0;
468
469	iap->ia_valid |= ATTR_CTIME;
470	return notify_change(&nop_mnt_idmap, dentry, iap, NULL);
471	}
472
473	/**
474	* nfsd_setattr - Set various file attributes.
475	* @rqstp: controlling RPC transaction
476	* @fhp: filehandle of target
477	* @attr: attributes to set
478	* @guardtime: do not act if ctime.tv_sec does not match this timestamp
479	*
480	* This call may adjust the contents of @attr (in particular, this
481	* call may change the bits in the na_iattr.ia_valid field).
482	*
483	* Returns nfs_ok on success, otherwise an NFS status code is
484	* returned. Caller must release @fhp by calling fh_put in either
485	* case.
486	*/
487	__be32
488	nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
489	struct nfsd_attrs *attr, const struct timespec64 *guardtime)
490	{
491	struct dentry *dentry;
492	struct inode *inode;
493	struct iattr *iap = attr->na_iattr;
494	int accmode = NFSD_MAY_SATTR;
495	umode_t ftype = 0;
496	__be32 err;
497	int host_err = 0;
498	bool get_write_count;
499	bool size_change = (iap->ia_valid & ATTR_SIZE);
500	int retries;
501
502	if (iap->ia_valid & ATTR_SIZE) {
503	accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
504	ftype = S_IFREG;
505	}
506
507	/*
508	* If utimes(2) and friends are called with times not NULL, we should
509	* not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
510	* will return EACCES, when the caller's effective UID does not match
511	* the owner of the file, and the caller is not privileged. In this
512	* situation, we should return EPERM(notify_change will return this).
513	*/
514	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
515	accmode |= NFSD_MAY_OWNER_OVERRIDE;
516	if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
517	accmode |= NFSD_MAY_WRITE;
518	}
519
520	/* Callers that do fh_verify should do the fh_want_write: */
521	get_write_count = !fhp->fh_dentry;
522
523	/* Get inode */
524	err = fh_verify(rqstp, fhp, ftype, accmode);
525	if (err)
526	return err;
527	if (get_write_count) {
528	host_err = fh_want_write(fh: fhp);
529	if (host_err)
530	goto out;
531	}
532
533	dentry = fhp->fh_dentry;
534	inode = d_inode(dentry);
535
536	nfsd_sanitize_attrs(inode, iap);
537
538	/*
539	* The size case is special, it changes the file in addition to the
540	* attributes, and file systems don't expect it to be mixed with
541	* "random" attribute changes. We thus split out the size change
542	* into a separate call to ->setattr, and do the rest as a separate
543	* setattr call.
544	*/
545	if (size_change) {
546	err = nfsd_get_write_access(rqstp, fhp, iap);
547	if (err)
548	return err;
549	}
550
551	inode_lock(inode);
552	err = fh_fill_pre_attrs(fhp);
553	if (err)
554	goto out_unlock;
555
556	if (guardtime) {
557	struct timespec64 ctime = inode_get_ctime(inode);
558	if ((u32)guardtime->tv_sec != (u32)ctime.tv_sec ||
559	guardtime->tv_nsec != ctime.tv_nsec) {
560	err = nfserr_notsync;
561	goto out_fill_attrs;
562	}
563	}
564
565	for (retries = 1;;) {
566	struct iattr attrs;
567
568	/*
569	* notify_change() can alter its iattr argument, making
570	* @iap unsuitable for submission multiple times. Make a
571	* copy for every loop iteration.
572	*/
573	attrs = *iap;
574	host_err = __nfsd_setattr(dentry, iap: &attrs);
575	if (host_err != -EAGAIN || !retries--)
576	break;
577	if (!nfsd_wait_for_delegreturn(rqstp, inode))
578	break;
579	}
580	if (attr->na_seclabel && attr->na_seclabel->len)
581	attr->na_labelerr = security_inode_setsecctx(dentry,
582	ctx: attr->na_seclabel->data, ctxlen: attr->na_seclabel->len);
583	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl)
584	attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
585	dentry, ACL_TYPE_ACCESS,
586	attr->na_pacl);
587	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) &&
588	!attr->na_aclerr && attr->na_dpacl && S_ISDIR(inode->i_mode))
589	attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
590	dentry, ACL_TYPE_DEFAULT,
591	attr->na_dpacl);
592	out_fill_attrs:
593	/*
594	* RFC 1813 Section 3.3.2 does not mandate that an NFS server
595	* returns wcc_data for SETATTR. Some client implementations
596	* depend on receiving wcc_data, however, to sort out partial
597	* updates (eg., the client requested that size and mode be
598	* modified, but the server changed only the file mode).
599	*/
600	fh_fill_post_attrs(fhp);
601	out_unlock:
602	inode_unlock(inode);
603	if (size_change)
604	put_write_access(inode);
605	out:
606	if (!host_err)
607	host_err = commit_metadata(fhp);
608	return err != 0 ? err : nfserrno(errno: host_err);
609	}
610
611	#if defined(CONFIG_NFSD_V4)
612	/*
613	* NFS junction information is stored in an extended attribute.
614	*/
615	#define NFSD_JUNCTION_XATTR_NAME XATTR_TRUSTED_PREFIX "junction.nfs"
616
617	/**
618	* nfsd4_is_junction - Test if an object could be an NFS junction
619	*
620	* @dentry: object to test
621	*
622	* Returns 1 if "dentry" appears to contain NFS junction information.
623	* Otherwise 0 is returned.
624	*/
625	int nfsd4_is_junction(struct dentry *dentry)
626	{
627	struct inode *inode = d_inode(dentry);
628
629	if (inode == NULL)
630	return 0;
631	if (inode->i_mode & S_IXUGO)
632	return 0;
633	if (!(inode->i_mode & S_ISVTX))
634	return 0;
635	if (vfs_getxattr(&nop_mnt_idmap, dentry, NFSD_JUNCTION_XATTR_NAME,
636	NULL, 0) <= 0)
637	return 0;
638	return 1;
639	}
640
641	static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
642	{
643	return &((struct nfsd4_compoundres *)rqstp->rq_resp)->cstate;
644	}
645
646	__be32 nfsd4_clone_file_range(struct svc_rqst *rqstp,
647	struct nfsd_file *nf_src, u64 src_pos,
648	struct nfsd_file *nf_dst, u64 dst_pos,
649	u64 count, bool sync)
650	{
651	struct file *src = nf_src->nf_file;
652	struct file *dst = nf_dst->nf_file;
653	errseq_t since;
654	loff_t cloned;
655	__be32 ret = 0;
656
657	since = READ_ONCE(dst->f_wb_err);
658	cloned = vfs_clone_file_range(file_in: src, pos_in: src_pos, file_out: dst, pos_out: dst_pos, len: count, remap_flags: 0);
659	if (cloned < 0) {
660	ret = nfserrno(errno: cloned);
661	goto out_err;
662	}
663	if (count && cloned != count) {
664	ret = nfserrno(errno: -EINVAL);
665	goto out_err;
666	}
667	if (sync) {
668	loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
669	int status = vfs_fsync_range(file: dst, start: dst_pos, end: dst_end, datasync: 0);
670
671	if (!status)
672	status = filemap_check_wb_err(mapping: dst->f_mapping, since);
673	if (!status)
674	status = commit_inode_metadata(inode: file_inode(f: src));
675	if (status < 0) {
676	struct nfsd_net *nn = net_generic(net: nf_dst->nf_net,
677	id: nfsd_net_id);
678
679	trace_nfsd_clone_file_range_err(rqstp,
680	src_fhp: &nfsd4_get_cstate(rqstp)->save_fh,
681	src_offset: src_pos,
682	dst_fhp: &nfsd4_get_cstate(rqstp)->current_fh,
683	dst_offset: dst_pos,
684	count, status);
685	commit_reset_write_verifier(nn, rqstp, err: status);
686	ret = nfserrno(errno: status);
687	}
688	}
689	out_err:
690	return ret;
691	}
692
693	ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
694	u64 dst_pos, u64 count)
695	{
696	ssize_t ret;
697
698	/*
699	* Limit copy to 4MB to prevent indefinitely blocking an nfsd
700	* thread and client rpc slot. The choice of 4MB is somewhat
701	* arbitrary. We might instead base this on r/wsize, or make it
702	* tunable, or use a time instead of a byte limit, or implement
703	* asynchronous copy. In theory a client could also recognize a
704	* limit like this and pipeline multiple COPY requests.
705	*/
706	count = min_t(u64, count, 1 << 22);
707	ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
708
709	if (ret == -EOPNOTSUPP || ret == -EXDEV)
710	ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count,
711	COPY_FILE_SPLICE);
712	return ret;
713	}
714
715	__be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
716	struct file *file, loff_t offset, loff_t len,
717	int flags)
718	{
719	int error;
720
721	if (!S_ISREG(file_inode(file)->i_mode))
722	return nfserr_inval;
723
724	error = vfs_fallocate(file, mode: flags, offset, len);
725	if (!error)
726	error = commit_metadata(fhp);
727
728	return nfserrno(errno: error);
729	}
730	#endif /* defined(CONFIG_NFSD_V4) */
731
732	/*
733	* Check server access rights to a file system object
734	*/
735	struct accessmap {
736	u32 access;
737	int how;
738	};
739	static struct accessmap nfs3_regaccess[] = {
740	{ NFS3_ACCESS_READ, NFSD_MAY_READ },
741	{ NFS3_ACCESS_EXECUTE, NFSD_MAY_EXEC },
742	{ NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_TRUNC },
743	{ NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE },
744
745	#ifdef CONFIG_NFSD_V4
746	{ NFS4_ACCESS_XAREAD, NFSD_MAY_READ },
747	{ NFS4_ACCESS_XAWRITE, NFSD_MAY_WRITE },
748	{ NFS4_ACCESS_XALIST, NFSD_MAY_READ },
749	#endif
750
751	{ 0, 0 }
752	};
753
754	static struct accessmap nfs3_diraccess[] = {
755	{ NFS3_ACCESS_READ, NFSD_MAY_READ },
756	{ NFS3_ACCESS_LOOKUP, NFSD_MAY_EXEC },
757	{ NFS3_ACCESS_MODIFY, NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
758	{ NFS3_ACCESS_EXTEND, NFSD_MAY_EXEC|NFSD_MAY_WRITE },
759	{ NFS3_ACCESS_DELETE, NFSD_MAY_REMOVE },
760
761	#ifdef CONFIG_NFSD_V4
762	{ NFS4_ACCESS_XAREAD, NFSD_MAY_READ },
763	{ NFS4_ACCESS_XAWRITE, NFSD_MAY_WRITE },
764	{ NFS4_ACCESS_XALIST, NFSD_MAY_READ },
765	#endif
766
767	{ 0, 0 }
768	};
769
770	static struct accessmap nfs3_anyaccess[] = {
771	/* Some clients - Solaris 2.6 at least, make an access call
772	* to the server to check for access for things like /dev/null
773	* (which really, the server doesn't care about). So
774	* We provide simple access checking for them, looking
775	* mainly at mode bits, and we make sure to ignore read-only
776	* filesystem checks
777	*/
778	{ NFS3_ACCESS_READ, NFSD_MAY_READ },
779	{ NFS3_ACCESS_EXECUTE, NFSD_MAY_EXEC },
780	{ NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS },
781	{ NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS },
782
783	{ 0, 0 }
784	};
785
786	__be32
787	nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
788	{
789	struct accessmap *map;
790	struct svc_export *export;
791	struct dentry *dentry;
792	u32 query, result = 0, sresult = 0;
793	__be32 error;
794
795	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
796	if (error)
797	goto out;
798
799	export = fhp->fh_export;
800	dentry = fhp->fh_dentry;
801
802	if (d_is_reg(dentry))
803	map = nfs3_regaccess;
804	else if (d_is_dir(dentry))
805	map = nfs3_diraccess;
806	else
807	map = nfs3_anyaccess;
808
809
810	query = *access;
811	for (; map->access; map++) {
812	if (map->access & query) {
813	__be32 err2;
814
815	sresult |= map->access;
816
817	err2 = nfsd_permission(rqstp, export, dentry, map->how);
818	switch (err2) {
819	case nfs_ok:
820	result |= map->access;
821	break;
822
823	/* the following error codes just mean the access was not allowed,
824	* rather than an error occurred */
825	case nfserr_rofs:
826	case nfserr_acces:
827	case nfserr_perm:
828	/* simply don't "or" in the access bit. */
829	break;
830	default:
831	error = err2;
832	goto out;
833	}
834	}
835	}
836	*access = result;
837	if (supported)
838	*supported = sresult;
839
840	out:
841	return error;
842	}
843
844	int nfsd_open_break_lease(struct inode *inode, int access)
845	{
846	unsigned int mode;
847
848	if (access & NFSD_MAY_NOT_BREAK_LEASE)
849	return 0;
850	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
851	return break_lease(inode, mode: mode | O_NONBLOCK);
852	}
853
854	/*
855	* Open an existing file or directory.
856	* The may_flags argument indicates the type of open (read/write/lock)
857	* and additional flags.
858	* N.B. After this call fhp needs an fh_put
859	*/
860	static int
861	__nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
862	int may_flags, struct file **filp)
863	{
864	struct path path;
865	struct inode *inode;
866	struct file *file;
867	int flags = O_RDONLY|O_LARGEFILE;
868	int host_err = -EPERM;
869
870	path.mnt = fhp->fh_export->ex_path.mnt;
871	path.dentry = fhp->fh_dentry;
872	inode = d_inode(dentry: path.dentry);
873
874	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
875	goto out;
876
877	if (!inode->i_fop)
878	goto out;
879
880	host_err = nfsd_open_break_lease(inode, access: may_flags);
881	if (host_err) /* NOMEM or WOULDBLOCK */
882	goto out;
883
884	if (may_flags & NFSD_MAY_WRITE) {
885	if (may_flags & NFSD_MAY_READ)
886	flags = O_RDWR|O_LARGEFILE;
887	else
888	flags = O_WRONLY|O_LARGEFILE;
889	}
890
891	file = dentry_open(path: &path, flags, current_cred());
892	if (IS_ERR(ptr: file)) {
893	host_err = PTR_ERR(ptr: file);
894	goto out;
895	}
896
897	host_err = security_file_post_open(file, mask: may_flags);
898	if (host_err) {
899	fput(file);
900	goto out;
901	}
902
903	if (may_flags & NFSD_MAY_64BIT_COOKIE)
904	file->f_mode |= FMODE_64BITHASH;
905	else
906	file->f_mode |= FMODE_32BITHASH;
907
908	*filp = file;
909	out:
910	return host_err;
911	}
912
913	__be32
914	nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
915	int may_flags, struct file **filp)
916	{
917	__be32 err;
918	int host_err;
919	bool retried = false;
920
921	/*
922	* If we get here, then the client has already done an "open",
923	* and (hopefully) checked permission - so allow OWNER_OVERRIDE
924	* in case a chmod has now revoked permission.
925	*
926	* Arguably we should also allow the owner override for
927	* directories, but we never have and it doesn't seem to have
928	* caused anyone a problem. If we were to change this, note
929	* also that our filldir callbacks would need a variant of
930	* lookup_one_len that doesn't check permissions.
931	*/
932	if (type == S_IFREG)
933	may_flags |= NFSD_MAY_OWNER_OVERRIDE;
934	retry:
935	err = fh_verify(rqstp, fhp, type, may_flags);
936	if (!err) {
937	host_err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
938	if (host_err == -EOPENSTALE && !retried) {
939	retried = true;
940	fh_put(fhp);
941	goto retry;
942	}
943	err = nfserrno(errno: host_err);
944	}
945	return err;
946	}
947
948	/**
949	* nfsd_open_verified - Open a regular file for the filecache
950	* @rqstp: RPC request
951	* @fhp: NFS filehandle of the file to open
952	* @may_flags: internal permission flags
953	* @filp: OUT: open "struct file *"
954	*
955	* Returns zero on success, or a negative errno value.
956	*/
957	int
958	nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags,
959	struct file **filp)
960	{
961	return __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp);
962	}
963
964	/*
965	* Grab and keep cached pages associated with a file in the svc_rqst
966	* so that they can be passed to the network sendmsg routines
967	* directly. They will be released after the sending has completed.
968	*
969	* Return values: Number of bytes consumed, or -EIO if there are no
970	* remaining pages in rqstp->rq_pages.
971	*/
972	static int
973	nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
974	struct splice_desc *sd)
975	{
976	struct svc_rqst *rqstp = sd->u.data;
977	struct page *page = buf->page; // may be a compound one
978	unsigned offset = buf->offset;
979	struct page *last_page;
980
981	last_page = page + (offset + sd->len - 1) / PAGE_SIZE;
982	for (page += offset / PAGE_SIZE; page <= last_page; page++) {
983	/*
984	* Skip page replacement when extending the contents of the
985	* current page. But note that we may get two zero_pages in a
986	* row from shmem.
987	*/
988	if (page == *(rqstp->rq_next_page - 1) &&
989	offset_in_page(rqstp->rq_res.page_base +
990	rqstp->rq_res.page_len))
991	continue;
992	if (unlikely(!svc_rqst_replace_page(rqstp, page)))
993	return -EIO;
994	}
995	if (rqstp->rq_res.page_len == 0) // first call
996	rqstp->rq_res.page_base = offset % PAGE_SIZE;
997	rqstp->rq_res.page_len += sd->len;
998	return sd->len;
999	}
1000
1001	static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
1002	struct splice_desc *sd)
1003	{
1004	return __splice_from_pipe(pipe, sd, actor: nfsd_splice_actor);
1005	}
1006
1007	static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
1008	size_t expected)
1009	{
1010	if (expected != 0 && len == 0)
1011	return 1;
1012	if (offset+len >= i_size_read(inode: file_inode(f: file)))
1013	return 1;
1014	return 0;
1015	}
1016
1017	static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1018	struct file *file, loff_t offset,
1019	unsigned long *count, u32 *eof, ssize_t host_err)
1020	{
1021	if (host_err >= 0) {
1022	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), id: nfsd_net_id);
1023
1024	nfsd_stats_io_read_add(nn, exp: fhp->fh_export, amount: host_err);
1025	*eof = nfsd_eof_on_read(file, offset, len: host_err, expected: *count);
1026	*count = host_err;
1027	fsnotify_access(file);
1028	trace_nfsd_read_io_done(rqstp, fhp, offset, len: *count);
1029	return 0;
1030	} else {
1031	trace_nfsd_read_err(rqstp, fhp, offset, len: host_err);
1032	return nfserrno(errno: host_err);
1033	}
1034	}
1035
1036	/**
1037	* nfsd_splice_read - Perform a VFS read using a splice pipe
1038	* @rqstp: RPC transaction context
1039	* @fhp: file handle of file to be read
1040	* @file: opened struct file of file to be read
1041	* @offset: starting byte offset
1042	* @count: IN: requested number of bytes; OUT: number of bytes read
1043	* @eof: OUT: set non-zero if operation reached the end of the file
1044	*
1045	* Returns nfs_ok on success, otherwise an nfserr stat value is
1046	* returned.
1047	*/
1048	__be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1049	struct file *file, loff_t offset, unsigned long *count,
1050	u32 *eof)
1051	{
1052	struct splice_desc sd = {
1053	.len = 0,
1054	.total_len = *count,
1055	.pos = offset,
1056	.u.data = rqstp,
1057	};
1058	ssize_t host_err;
1059
1060	trace_nfsd_read_splice(rqstp, fhp, offset, len: *count);
1061	host_err = rw_verify_area(READ, file, &offset, *count);
1062	if (!host_err)
1063	host_err = splice_direct_to_actor(file, sd: &sd,
1064	actor: nfsd_direct_splice_actor);
1065	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
1066	}
1067
1068	/**
1069	* nfsd_iter_read - Perform a VFS read using an iterator
1070	* @rqstp: RPC transaction context
1071	* @fhp: file handle of file to be read
1072	* @file: opened struct file of file to be read
1073	* @offset: starting byte offset
1074	* @count: IN: requested number of bytes; OUT: number of bytes read
1075	* @base: offset in first page of read buffer
1076	* @eof: OUT: set non-zero if operation reached the end of the file
1077	*
1078	* Some filesystems or situations cannot use nfsd_splice_read. This
1079	* function is the slightly less-performant fallback for those cases.
1080	*
1081	* Returns nfs_ok on success, otherwise an nfserr stat value is
1082	* returned.
1083	*/
1084	__be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1085	struct file *file, loff_t offset, unsigned long *count,
1086	unsigned int base, u32 *eof)
1087	{
1088	unsigned long v, total;
1089	struct iov_iter iter;
1090	loff_t ppos = offset;
1091	struct page *page;
1092	ssize_t host_err;
1093
1094	v = 0;
1095	total = *count;
1096	while (total) {
1097	page = *(rqstp->rq_next_page++);
1098	rqstp->rq_vec[v].iov_base = page_address(page) + base;
1099	rqstp->rq_vec[v].iov_len = min_t(size_t, total, PAGE_SIZE - base);
1100	total -= rqstp->rq_vec[v].iov_len;
1101	++v;
1102	base = 0;
1103	}
1104	WARN_ON_ONCE(v > ARRAY_SIZE(rqstp->rq_vec));
1105
1106	trace_nfsd_read_vector(rqstp, fhp, offset, len: *count);
1107	iov_iter_kvec(i: &iter, ITER_DEST, kvec: rqstp->rq_vec, nr_segs: v, count: *count);
1108	host_err = vfs_iter_read(file, iter: &iter, ppos: &ppos, flags: 0);
1109	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
1110	}
1111
1112	/*
1113	* Gathered writes: If another process is currently writing to the file,
1114	* there's a high chance this is another nfsd (triggered by a bulk write
1115	* from a client's biod). Rather than syncing the file with each write
1116	* request, we sleep for 10 msec.
1117	*
1118	* I don't know if this roughly approximates C. Juszak's idea of
1119	* gathered writes, but it's a nice and simple solution (IMHO), and it
1120	* seems to work:-)
1121	*
1122	* Note: we do this only in the NFSv2 case, since v3 and higher have a
1123	* better tool (separate unstable writes and commits) for solving this
1124	* problem.
1125	*/
1126	static int wait_for_concurrent_writes(struct file *file)
1127	{
1128	struct inode *inode = file_inode(f: file);
1129	static ino_t last_ino;
1130	static dev_t last_dev;
1131	int err = 0;
1132
1133	if (atomic_read(v: &inode->i_writecount) > 1
1134	|| (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
1135	dprintk("nfsd: write defer %d\n", task_pid_nr(current));
1136	msleep(msecs: 10);
1137	dprintk("nfsd: write resume %d\n", task_pid_nr(current));
1138	}
1139
1140	if (inode->i_state & I_DIRTY) {
1141	dprintk("nfsd: write sync %d\n", task_pid_nr(current));
1142	err = vfs_fsync(file, datasync: 0);
1143	}
1144	last_ino = inode->i_ino;
1145	last_dev = inode->i_sb->s_dev;
1146	return err;
1147	}
1148
1149	__be32
1150	nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
1151	loff_t offset, struct kvec *vec, int vlen,
1152	unsigned long *cnt, int stable,
1153	__be32 *verf)
1154	{
1155	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), id: nfsd_net_id);
1156	struct file *file = nf->nf_file;
1157	struct super_block *sb = file_inode(f: file)->i_sb;
1158	struct svc_export *exp;
1159	struct iov_iter iter;
1160	errseq_t since;
1161	__be32 nfserr;
1162	int host_err;
1163	int use_wgather;
1164	loff_t pos = offset;
1165	unsigned long exp_op_flags = 0;
1166	unsigned int pflags = current->flags;
1167	rwf_t flags = 0;
1168	bool restore_flags = false;
1169
1170	trace_nfsd_write_opened(rqstp, fhp, offset, len: *cnt);
1171
1172	if (sb->s_export_op)
1173	exp_op_flags = sb->s_export_op->flags;
1174
1175	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
1176	!(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
1177	/*
1178	* We want throttling in balance_dirty_pages()
1179	* and shrink_inactive_list() to only consider
1180	* the backingdev we are writing to, so that nfs to
1181	* localhost doesn't cause nfsd to lock up due to all
1182	* the client's dirty pages or its congested queue.
1183	*/
1184	current->flags |= PF_LOCAL_THROTTLE;
1185	restore_flags = true;
1186	}
1187
1188	exp = fhp->fh_export;
1189	use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
1190
1191	if (!EX_ISSYNC(exp))
1192	stable = NFS_UNSTABLE;
1193
1194	if (stable && !use_wgather)
1195	flags |= RWF_SYNC;
1196
1197	iov_iter_kvec(i: &iter, ITER_SOURCE, kvec: vec, nr_segs: vlen, count: *cnt);
1198	since = READ_ONCE(file->f_wb_err);
1199	if (verf)
1200	nfsd_copy_write_verifier(verf, nn);
1201	host_err = vfs_iter_write(file, iter: &iter, ppos: &pos, flags);
1202	if (host_err < 0) {
1203	commit_reset_write_verifier(nn, rqstp, err: host_err);
1204	goto out_nfserr;
1205	}
1206	*cnt = host_err;
1207	nfsd_stats_io_write_add(nn, exp, amount: *cnt);
1208	fsnotify_modify(file);
1209	host_err = filemap_check_wb_err(mapping: file->f_mapping, since);
1210	if (host_err < 0)
1211	goto out_nfserr;
1212
1213	if (stable && use_wgather) {
1214	host_err = wait_for_concurrent_writes(file);
1215	if (host_err < 0)
1216	commit_reset_write_verifier(nn, rqstp, err: host_err);
1217	}
1218
1219	out_nfserr:
1220	if (host_err >= 0) {
1221	trace_nfsd_write_io_done(rqstp, fhp, offset, len: *cnt);
1222	nfserr = nfs_ok;
1223	} else {
1224	trace_nfsd_write_err(rqstp, fhp, offset, len: host_err);
1225	nfserr = nfserrno(errno: host_err);
1226	}
1227	if (restore_flags)
1228	current_restore_flags(orig_flags: pflags, PF_LOCAL_THROTTLE);
1229	return nfserr;
1230	}
1231
1232	/**
1233	* nfsd_read_splice_ok - check if spliced reading is supported
1234	* @rqstp: RPC transaction context
1235	*
1236	* Return values:
1237	* %true: nfsd_splice_read() may be used
1238	* %false: nfsd_splice_read() must not be used
1239	*
1240	* NFS READ normally uses splice to send data in-place. However the
1241	* data in cache can change after the reply's MIC is computed but
1242	* before the RPC reply is sent. To prevent the client from
1243	* rejecting the server-computed MIC in this somewhat rare case, do
1244	* not use splice with the GSS integrity and privacy services.
1245	*/
1246	bool nfsd_read_splice_ok(struct svc_rqst *rqstp)
1247	{
1248	switch (svc_auth_flavor(rqstp)) {
1249	case RPC_AUTH_GSS_KRB5I:
1250	case RPC_AUTH_GSS_KRB5P:
1251	return false;
1252	}
1253	return true;
1254	}
1255
1256	/**
1257	* nfsd_read - Read data from a file
1258	* @rqstp: RPC transaction context
1259	* @fhp: file handle of file to be read
1260	* @offset: starting byte offset
1261	* @count: IN: requested number of bytes; OUT: number of bytes read
1262	* @eof: OUT: set non-zero if operation reached the end of the file
1263	*
1264	* The caller must verify that there is enough space in @rqstp.rq_res
1265	* to perform this operation.
1266	*
1267	* N.B. After this call fhp needs an fh_put
1268	*
1269	* Returns nfs_ok on success, otherwise an nfserr stat value is
1270	* returned.
1271	*/
1272	__be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1273	loff_t offset, unsigned long *count, u32 *eof)
1274	{
1275	struct nfsd_file *nf;
1276	struct file *file;
1277	__be32 err;
1278
1279	trace_nfsd_read_start(rqstp, fhp, offset, len: *count);
1280	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_READ, nfp: &nf);
1281	if (err)
1282	return err;
1283
1284	file = nf->nf_file;
1285	if (file->f_op->splice_read && nfsd_read_splice_ok(rqstp))
1286	err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1287	else
1288	err = nfsd_iter_read(rqstp, fhp, file, offset, count, base: 0, eof);
1289
1290	nfsd_file_put(nf);
1291	trace_nfsd_read_done(rqstp, fhp, offset, len: *count);
1292	return err;
1293	}
1294
1295	/*
1296	* Write data to a file.
1297	* The stable flag requests synchronous writes.
1298	* N.B. After this call fhp needs an fh_put
1299	*/
1300	__be32
1301	nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1302	struct kvec *vec, int vlen, unsigned long *cnt, int stable,
1303	__be32 *verf)
1304	{
1305	struct nfsd_file *nf;
1306	__be32 err;
1307
1308	trace_nfsd_write_start(rqstp, fhp, offset, len: *cnt);
1309
1310	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_WRITE, nfp: &nf);
1311	if (err)
1312	goto out;
1313
1314	err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
1315	vlen, cnt, stable, verf);
1316	nfsd_file_put(nf);
1317	out:
1318	trace_nfsd_write_done(rqstp, fhp, offset, len: *cnt);
1319	return err;
1320	}
1321
1322	/**
1323	* nfsd_commit - Commit pending writes to stable storage
1324	* @rqstp: RPC request being processed
1325	* @fhp: NFS filehandle
1326	* @nf: target file
1327	* @offset: raw offset from beginning of file
1328	* @count: raw count of bytes to sync
1329	* @verf: filled in with the server's current write verifier
1330	*
1331	* Note: we guarantee that data that lies within the range specified
1332	* by the 'offset' and 'count' parameters will be synced. The server
1333	* is permitted to sync data that lies outside this range at the
1334	* same time.
1335	*
1336	* Unfortunately we cannot lock the file to make sure we return full WCC
1337	* data to the client, as locking happens lower down in the filesystem.
1338	*
1339	* Return values:
1340	* An nfsstat value in network byte order.
1341	*/
1342	__be32
1343	nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
1344	u64 offset, u32 count, __be32 *verf)
1345	{
1346	__be32 err = nfs_ok;
1347	u64 maxbytes;
1348	loff_t start, end;
1349	struct nfsd_net *nn;
1350
1351	/*
1352	* Convert the client-provided (offset, count) range to a
1353	* (start, end) range. If the client-provided range falls
1354	* outside the maximum file size of the underlying FS,
1355	* clamp the sync range appropriately.
1356	*/
1357	start = 0;
1358	end = LLONG_MAX;
1359	maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
1360	if (offset < maxbytes) {
1361	start = offset;
1362	if (count && (offset + count - 1 < maxbytes))
1363	end = offset + count - 1;
1364	}
1365
1366	nn = net_generic(net: nf->nf_net, id: nfsd_net_id);
1367	if (EX_ISSYNC(fhp->fh_export)) {
1368	errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
1369	int err2;
1370
1371	err2 = vfs_fsync_range(file: nf->nf_file, start, end, datasync: 0);
1372	switch (err2) {
1373	case 0:
1374	nfsd_copy_write_verifier(verf, nn);
1375	err2 = filemap_check_wb_err(mapping: nf->nf_file->f_mapping,
1376	since);
1377	err = nfserrno(errno: err2);
1378	break;
1379	case -EINVAL:
1380	err = nfserr_notsupp;
1381	break;
1382	default:
1383	commit_reset_write_verifier(nn, rqstp, err: err2);
1384	err = nfserrno(errno: err2);
1385	}
1386	} else
1387	nfsd_copy_write_verifier(verf, nn);
1388
1389	return err;
1390	}
1391
1392	/**
1393	* nfsd_create_setattr - Set a created file's attributes
1394	* @rqstp: RPC transaction being executed
1395	* @fhp: NFS filehandle of parent directory
1396	* @resfhp: NFS filehandle of new object
1397	* @attrs: requested attributes of new object
1398	*
1399	* Returns nfs_ok on success, or an nfsstat in network byte order.
1400	*/
1401	__be32
1402	nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
1403	struct svc_fh *resfhp, struct nfsd_attrs *attrs)
1404	{
1405	struct iattr *iap = attrs->na_iattr;
1406	__be32 status;
1407
1408	/*
1409	* Mode has already been set by file creation.
1410	*/
1411	iap->ia_valid &= ~ATTR_MODE;
1412
1413	/*
1414	* Setting uid/gid works only for root. Irix appears to
1415	* send along the gid on create when it tries to implement
1416	* setgid directories via NFS:
1417	*/
1418	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1419	iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1420
1421	/*
1422	* Callers expect new file metadata to be committed even
1423	* if the attributes have not changed.
1424	*/
1425	if (iap->ia_valid)
1426	status = nfsd_setattr(rqstp, resfhp, attrs, NULL);
1427	else
1428	status = nfserrno(commit_metadata(resfhp));
1429
1430	/*
1431	* Transactional filesystems had a chance to commit changes
1432	* for both parent and child simultaneously making the
1433	* following commit_metadata a noop in many cases.
1434	*/
1435	if (!status)
1436	status = nfserrno(commit_metadata(fhp));
1437
1438	/*
1439	* Update the new filehandle to pick up the new attributes.
1440	*/
1441	if (!status)
1442	status = fh_update(resfhp);
1443
1444	return status;
1445	}
1446
1447	/* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1448	* setting size to 0 may fail for some specific file systems by the permission
1449	* checking which requires WRITE permission but the mode is 000.
1450	* we ignore the resizing(to 0) on the just new created file, since the size is
1451	* 0 after file created.
1452	*
1453	* call this only after vfs_create() is called.
1454	* */
1455	static void
1456	nfsd_check_ignore_resizing(struct iattr *iap)
1457	{
1458	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1459	iap->ia_valid &= ~ATTR_SIZE;
1460	}
1461
1462	/* The parent directory should already be locked: */
1463	__be32
1464	nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1465	struct nfsd_attrs *attrs,
1466	int type, dev_t rdev, struct svc_fh *resfhp)
1467	{
1468	struct dentry *dentry, *dchild;
1469	struct inode *dirp;
1470	struct iattr *iap = attrs->na_iattr;
1471	__be32 err;
1472	int host_err;
1473
1474	dentry = fhp->fh_dentry;
1475	dirp = d_inode(dentry);
1476
1477	dchild = dget(dentry: resfhp->fh_dentry);
1478	err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1479	if (err)
1480	goto out;
1481
1482	if (!(iap->ia_valid & ATTR_MODE))
1483	iap->ia_mode = 0;
1484	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1485
1486	if (!IS_POSIXACL(dirp))
1487	iap->ia_mode &= ~current_umask();
1488
1489	err = 0;
1490	switch (type) {
1491	case S_IFREG:
1492	host_err = vfs_create(&nop_mnt_idmap, dirp, dchild,
1493	iap->ia_mode, true);
1494	if (!host_err)
1495	nfsd_check_ignore_resizing(iap);
1496	break;
1497	case S_IFDIR:
1498	host_err = vfs_mkdir(&nop_mnt_idmap, dirp, dchild, iap->ia_mode);
1499	if (!host_err && unlikely(d_unhashed(dchild))) {
1500	struct dentry *d;
1501	d = lookup_one_len(dchild->d_name.name,
1502	dchild->d_parent,
1503	dchild->d_name.len);
1504	if (IS_ERR(ptr: d)) {
1505	host_err = PTR_ERR(ptr: d);
1506	break;
1507	}
1508	if (unlikely(d_is_negative(d))) {
1509	dput(d);
1510	err = nfserr_serverfault;
1511	goto out;
1512	}
1513	dput(resfhp->fh_dentry);
1514	resfhp->fh_dentry = dget(dentry: d);
1515	err = fh_update(resfhp);
1516	dput(dchild);
1517	dchild = d;
1518	if (err)
1519	goto out;
1520	}
1521	break;
1522	case S_IFCHR:
1523	case S_IFBLK:
1524	case S_IFIFO:
1525	case S_IFSOCK:
1526	host_err = vfs_mknod(&nop_mnt_idmap, dirp, dchild,
1527	iap->ia_mode, rdev);
1528	break;
1529	default:
1530	printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1531	type);
1532	host_err = -EINVAL;
1533	}
1534	if (host_err < 0)
1535	goto out_nfserr;
1536
1537	err = nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1538
1539	out:
1540	dput(dchild);
1541	return err;
1542
1543	out_nfserr:
1544	err = nfserrno(errno: host_err);
1545	goto out;
1546	}
1547
1548	/*
1549	* Create a filesystem object (regular, directory, special).
1550	* Note that the parent directory is left locked.
1551	*
1552	* N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1553	*/
1554	__be32
1555	nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1556	char *fname, int flen, struct nfsd_attrs *attrs,
1557	int type, dev_t rdev, struct svc_fh *resfhp)
1558	{
1559	struct dentry *dentry, *dchild = NULL;
1560	__be32 err;
1561	int host_err;
1562
1563	if (isdotent(fname, flen))
1564	return nfserr_exist;
1565
1566	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1567	if (err)
1568	return err;
1569
1570	dentry = fhp->fh_dentry;
1571
1572	host_err = fh_want_write(fh: fhp);
1573	if (host_err)
1574	return nfserrno(errno: host_err);
1575
1576	inode_lock_nested(inode: dentry->d_inode, subclass: I_MUTEX_PARENT);
1577	dchild = lookup_one_len(fname, dentry, flen);
1578	host_err = PTR_ERR(ptr: dchild);
1579	if (IS_ERR(ptr: dchild)) {
1580	err = nfserrno(errno: host_err);
1581	goto out_unlock;
1582	}
1583	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1584	/*
1585	* We unconditionally drop our ref to dchild as fh_compose will have
1586	* already grabbed its own ref for it.
1587	*/
1588	dput(dchild);
1589	if (err)
1590	goto out_unlock;
1591	err = fh_fill_pre_attrs(fhp);
1592	if (err != nfs_ok)
1593	goto out_unlock;
1594	err = nfsd_create_locked(rqstp, fhp, attrs, type, rdev, resfhp);
1595	fh_fill_post_attrs(fhp);
1596	out_unlock:
1597	inode_unlock(inode: dentry->d_inode);
1598	return err;
1599	}
1600
1601	/*
1602	* Read a symlink. On entry, *lenp must contain the maximum path length that
1603	* fits into the buffer. On return, it contains the true length.
1604	* N.B. After this call fhp needs an fh_put
1605	*/
1606	__be32
1607	nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1608	{
1609	__be32 err;
1610	const char *link;
1611	struct path path;
1612	DEFINE_DELAYED_CALL(done);
1613	int len;
1614
1615	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1616	if (unlikely(err))
1617	return err;
1618
1619	path.mnt = fhp->fh_export->ex_path.mnt;
1620	path.dentry = fhp->fh_dentry;
1621
1622	if (unlikely(!d_is_symlink(path.dentry)))
1623	return nfserr_inval;
1624
1625	touch_atime(&path);
1626
1627	link = vfs_get_link(path.dentry, &done);
1628	if (IS_ERR(ptr: link))
1629	return nfserrno(errno: PTR_ERR(ptr: link));
1630
1631	len = strlen(link);
1632	if (len < *lenp)
1633	*lenp = len;
1634	memcpy(buf, link, *lenp);
1635	do_delayed_call(call: &done);
1636	return 0;
1637	}
1638
1639	/**
1640	* nfsd_symlink - Create a symlink and look up its inode
1641	* @rqstp: RPC transaction being executed
1642	* @fhp: NFS filehandle of parent directory
1643	* @fname: filename of the new symlink
1644	* @flen: length of @fname
1645	* @path: content of the new symlink (NUL-terminated)
1646	* @attrs: requested attributes of new object
1647	* @resfhp: NFS filehandle of new object
1648	*
1649	* N.B. After this call _both_ fhp and resfhp need an fh_put
1650	*
1651	* Returns nfs_ok on success, or an nfsstat in network byte order.
1652	*/
1653	__be32
1654	nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1655	char *fname, int flen,
1656	char *path, struct nfsd_attrs *attrs,
1657	struct svc_fh *resfhp)
1658	{
1659	struct dentry *dentry, *dnew;
1660	__be32 err, cerr;
1661	int host_err;
1662
1663	err = nfserr_noent;
1664	if (!flen || path[0] == '\0')
1665	goto out;
1666	err = nfserr_exist;
1667	if (isdotent(fname, flen))
1668	goto out;
1669
1670	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1671	if (err)
1672	goto out;
1673
1674	host_err = fh_want_write(fh: fhp);
1675	if (host_err) {
1676	err = nfserrno(errno: host_err);
1677	goto out;
1678	}
1679
1680	dentry = fhp->fh_dentry;
1681	inode_lock_nested(inode: dentry->d_inode, subclass: I_MUTEX_PARENT);
1682	dnew = lookup_one_len(fname, dentry, flen);
1683	if (IS_ERR(ptr: dnew)) {
1684	err = nfserrno(errno: PTR_ERR(ptr: dnew));
1685	inode_unlock(inode: dentry->d_inode);
1686	goto out_drop_write;
1687	}
1688	err = fh_fill_pre_attrs(fhp);
1689	if (err != nfs_ok)
1690	goto out_unlock;
1691	host_err = vfs_symlink(&nop_mnt_idmap, d_inode(dentry), dnew, path);
1692	err = nfserrno(errno: host_err);
1693	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1694	if (!err)
1695	nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1696	fh_fill_post_attrs(fhp);
1697	out_unlock:
1698	inode_unlock(inode: dentry->d_inode);
1699	if (!err)
1700	err = nfserrno(errno: commit_metadata(fhp));
1701	dput(dnew);
1702	if (err==0) err = cerr;
1703	out_drop_write:
1704	fh_drop_write(fh: fhp);
1705	out:
1706	return err;
1707	}
1708
1709	/*
1710	* Create a hardlink
1711	* N.B. After this call _both_ ffhp and tfhp need an fh_put
1712	*/
1713	__be32
1714	nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1715	char *name, int len, struct svc_fh *tfhp)
1716	{
1717	struct dentry *ddir, *dnew, *dold;
1718	struct inode *dirp;
1719	__be32 err;
1720	int host_err;
1721
1722	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1723	if (err)
1724	goto out;
1725	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1726	if (err)
1727	goto out;
1728	err = nfserr_isdir;
1729	if (d_is_dir(dentry: tfhp->fh_dentry))
1730	goto out;
1731	err = nfserr_perm;
1732	if (!len)
1733	goto out;
1734	err = nfserr_exist;
1735	if (isdotent(name, len))
1736	goto out;
1737
1738	host_err = fh_want_write(fh: tfhp);
1739	if (host_err) {
1740	err = nfserrno(errno: host_err);
1741	goto out;
1742	}
1743
1744	ddir = ffhp->fh_dentry;
1745	dirp = d_inode(dentry: ddir);
1746	inode_lock_nested(inode: dirp, subclass: I_MUTEX_PARENT);
1747
1748	dnew = lookup_one_len(name, ddir, len);
1749	if (IS_ERR(ptr: dnew)) {
1750	err = nfserrno(errno: PTR_ERR(ptr: dnew));
1751	goto out_unlock;
1752	}
1753
1754	dold = tfhp->fh_dentry;
1755
1756	err = nfserr_noent;
1757	if (d_really_is_negative(dentry: dold))
1758	goto out_dput;
1759	err = fh_fill_pre_attrs(fhp: ffhp);
1760	if (err != nfs_ok)
1761	goto out_dput;
1762	host_err = vfs_link(dold, &nop_mnt_idmap, dirp, dnew, NULL);
1763	fh_fill_post_attrs(fhp: ffhp);
1764	inode_unlock(inode: dirp);
1765	if (!host_err) {
1766	err = nfserrno(errno: commit_metadata(fhp: ffhp));
1767	if (!err)
1768	err = nfserrno(errno: commit_metadata(fhp: tfhp));
1769	} else {
1770	if (host_err == -EXDEV && rqstp->rq_vers == 2)
1771	err = nfserr_acces;
1772	else
1773	err = nfserrno(errno: host_err);
1774	}
1775	dput(dnew);
1776	out_drop_write:
1777	fh_drop_write(fh: tfhp);
1778	out:
1779	return err;
1780
1781	out_dput:
1782	dput(dnew);
1783	out_unlock:
1784	inode_unlock(inode: dirp);
1785	goto out_drop_write;
1786	}
1787
1788	static void
1789	nfsd_close_cached_files(struct dentry *dentry)
1790	{
1791	struct inode *inode = d_inode(dentry);
1792
1793	if (inode && S_ISREG(inode->i_mode))
1794	nfsd_file_close_inode_sync(inode);
1795	}
1796
1797	static bool
1798	nfsd_has_cached_files(struct dentry *dentry)
1799	{
1800	bool ret = false;
1801	struct inode *inode = d_inode(dentry);
1802
1803	if (inode && S_ISREG(inode->i_mode))
1804	ret = nfsd_file_is_cached(inode);
1805	return ret;
1806	}
1807
1808	/*
1809	* Rename a file
1810	* N.B. After this call _both_ ffhp and tfhp need an fh_put
1811	*/
1812	__be32
1813	nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1814	struct svc_fh *tfhp, char *tname, int tlen)
1815	{
1816	struct dentry *fdentry, *tdentry, *odentry, *ndentry, *trap;
1817	struct inode *fdir, *tdir;
1818	__be32 err;
1819	int host_err;
1820	bool close_cached = false;
1821
1822	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1823	if (err)
1824	goto out;
1825	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1826	if (err)
1827	goto out;
1828
1829	fdentry = ffhp->fh_dentry;
1830	fdir = d_inode(dentry: fdentry);
1831
1832	tdentry = tfhp->fh_dentry;
1833	tdir = d_inode(dentry: tdentry);
1834
1835	err = nfserr_perm;
1836	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1837	goto out;
1838
1839	err = (rqstp->rq_vers == 2) ? nfserr_acces : nfserr_xdev;
1840	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1841	goto out;
1842	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1843	goto out;
1844
1845	retry:
1846	host_err = fh_want_write(fh: ffhp);
1847	if (host_err) {
1848	err = nfserrno(errno: host_err);
1849	goto out;
1850	}
1851
1852	trap = lock_rename(tdentry, fdentry);
1853	if (IS_ERR(ptr: trap)) {
1854	err = (rqstp->rq_vers == 2) ? nfserr_acces : nfserr_xdev;
1855	goto out_want_write;
1856	}
1857	err = fh_fill_pre_attrs(fhp: ffhp);
1858	if (err != nfs_ok)
1859	goto out_unlock;
1860	err = fh_fill_pre_attrs(fhp: tfhp);
1861	if (err != nfs_ok)
1862	goto out_unlock;
1863
1864	odentry = lookup_one_len(fname, fdentry, flen);
1865	host_err = PTR_ERR(ptr: odentry);
1866	if (IS_ERR(ptr: odentry))
1867	goto out_nfserr;
1868
1869	host_err = -ENOENT;
1870	if (d_really_is_negative(dentry: odentry))
1871	goto out_dput_old;
1872	host_err = -EINVAL;
1873	if (odentry == trap)
1874	goto out_dput_old;
1875
1876	ndentry = lookup_one_len(tname, tdentry, tlen);
1877	host_err = PTR_ERR(ptr: ndentry);
1878	if (IS_ERR(ptr: ndentry))
1879	goto out_dput_old;
1880	host_err = -ENOTEMPTY;
1881	if (ndentry == trap)
1882	goto out_dput_new;
1883
1884	if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
1885	nfsd_has_cached_files(dentry: ndentry)) {
1886	close_cached = true;
1887	goto out_dput_old;
1888	} else {
1889	struct renamedata rd = {
1890	.old_mnt_idmap = &nop_mnt_idmap,
1891	.old_dir = fdir,
1892	.old_dentry = odentry,
1893	.new_mnt_idmap = &nop_mnt_idmap,
1894	.new_dir = tdir,
1895	.new_dentry = ndentry,
1896	};
1897	int retries;
1898
1899	for (retries = 1;;) {
1900	host_err = vfs_rename(&rd);
1901	if (host_err != -EAGAIN || !retries--)
1902	break;
1903	if (!nfsd_wait_for_delegreturn(rqstp, inode: d_inode(dentry: odentry)))
1904	break;
1905	}
1906	if (!host_err) {
1907	host_err = commit_metadata(fhp: tfhp);
1908	if (!host_err)
1909	host_err = commit_metadata(fhp: ffhp);
1910	}
1911	}
1912	out_dput_new:
1913	dput(ndentry);
1914	out_dput_old:
1915	dput(odentry);
1916	out_nfserr:
1917	err = nfserrno(errno: host_err);
1918
1919	if (!close_cached) {
1920	fh_fill_post_attrs(fhp: ffhp);
1921	fh_fill_post_attrs(fhp: tfhp);
1922	}
1923	out_unlock:
1924	unlock_rename(tdentry, fdentry);
1925	out_want_write:
1926	fh_drop_write(fh: ffhp);
1927
1928	/*
1929	* If the target dentry has cached open files, then we need to
1930	* try to close them prior to doing the rename. Final fput
1931	* shouldn't be done with locks held however, so we delay it
1932	* until this point and then reattempt the whole shebang.
1933	*/
1934	if (close_cached) {
1935	close_cached = false;
1936	nfsd_close_cached_files(dentry: ndentry);
1937	dput(ndentry);
1938	goto retry;
1939	}
1940	out:
1941	return err;
1942	}
1943
1944	/*
1945	* Unlink a file or directory
1946	* N.B. After this call fhp needs an fh_put
1947	*/
1948	__be32
1949	nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1950	char *fname, int flen)
1951	{
1952	struct dentry *dentry, *rdentry;
1953	struct inode *dirp;
1954	struct inode *rinode;
1955	__be32 err;
1956	int host_err;
1957
1958	err = nfserr_acces;
1959	if (!flen || isdotent(fname, flen))
1960	goto out;
1961	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1962	if (err)
1963	goto out;
1964
1965	host_err = fh_want_write(fh: fhp);
1966	if (host_err)
1967	goto out_nfserr;
1968
1969	dentry = fhp->fh_dentry;
1970	dirp = d_inode(dentry);
1971	inode_lock_nested(inode: dirp, subclass: I_MUTEX_PARENT);
1972
1973	rdentry = lookup_one_len(fname, dentry, flen);
1974	host_err = PTR_ERR(ptr: rdentry);
1975	if (IS_ERR(ptr: rdentry))
1976	goto out_unlock;
1977
1978	if (d_really_is_negative(dentry: rdentry)) {
1979	dput(rdentry);
1980	host_err = -ENOENT;
1981	goto out_unlock;
1982	}
1983	rinode = d_inode(dentry: rdentry);
1984	err = fh_fill_pre_attrs(fhp);
1985	if (err != nfs_ok)
1986	goto out_unlock;
1987
1988	ihold(inode: rinode);
1989	if (!type)
1990	type = d_inode(dentry: rdentry)->i_mode & S_IFMT;
1991
1992	if (type != S_IFDIR) {
1993	int retries;
1994
1995	if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
1996	nfsd_close_cached_files(dentry: rdentry);
1997
1998	for (retries = 1;;) {
1999	host_err = vfs_unlink(&nop_mnt_idmap, dirp, rdentry, NULL);
2000	if (host_err != -EAGAIN || !retries--)
2001	break;
2002	if (!nfsd_wait_for_delegreturn(rqstp, inode: rinode))
2003	break;
2004	}
2005	} else {
2006	host_err = vfs_rmdir(&nop_mnt_idmap, dirp, rdentry);
2007	}
2008	fh_fill_post_attrs(fhp);
2009
2010	inode_unlock(inode: dirp);
2011	if (!host_err)
2012	host_err = commit_metadata(fhp);
2013	dput(rdentry);
2014	iput(rinode); /* truncate the inode here */
2015
2016	out_drop_write:
2017	fh_drop_write(fh: fhp);
2018	out_nfserr:
2019	if (host_err == -EBUSY) {
2020	/* name is mounted-on. There is no perfect
2021	* error status.
2022	*/
2023	if (nfsd_v4client(rq: rqstp))
2024	err = nfserr_file_open;
2025	else
2026	err = nfserr_acces;
2027	} else {
2028	err = nfserrno(errno: host_err);
2029	}
2030	out:
2031	return err;
2032	out_unlock:
2033	inode_unlock(inode: dirp);
2034	goto out_drop_write;
2035	}
2036
2037	/*
2038	* We do this buffering because we must not call back into the file
2039	* system's ->lookup() method from the filldir callback. That may well
2040	* deadlock a number of file systems.
2041	*
2042	* This is based heavily on the implementation of same in XFS.
2043	*/
2044	struct buffered_dirent {
2045	u64 ino;
2046	loff_t offset;
2047	int namlen;
2048	unsigned int d_type;
2049	char name[];
2050	};
2051
2052	struct readdir_data {
2053	struct dir_context ctx;
2054	char *dirent;
2055	size_t used;
2056	int full;
2057	};
2058
2059	static bool nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
2060	int namlen, loff_t offset, u64 ino,
2061	unsigned int d_type)
2062	{
2063	struct readdir_data *buf =
2064	container_of(ctx, struct readdir_data, ctx);
2065	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
2066	unsigned int reclen;
2067
2068	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
2069	if (buf->used + reclen > PAGE_SIZE) {
2070	buf->full = 1;
2071	return false;
2072	}
2073
2074	de->namlen = namlen;
2075	de->offset = offset;
2076	de->ino = ino;
2077	de->d_type = d_type;
2078	memcpy(de->name, name, namlen);
2079	buf->used += reclen;
2080
2081	return true;
2082	}
2083
2084	static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
2085	nfsd_filldir_t func, struct readdir_cd *cdp,
2086	loff_t *offsetp)
2087	{
2088	struct buffered_dirent *de;
2089	int host_err;
2090	int size;
2091	loff_t offset;
2092	struct readdir_data buf = {
2093	.ctx.actor = nfsd_buffered_filldir,
2094	.dirent = (void *)__get_free_page(GFP_KERNEL)
2095	};
2096
2097	if (!buf.dirent)
2098	return nfserrno(errno: -ENOMEM);
2099
2100	offset = *offsetp;
2101
2102	while (1) {
2103	unsigned int reclen;
2104
2105	cdp->err = nfserr_eof; /* will be cleared on successful read */
2106	buf.used = 0;
2107	buf.full = 0;
2108
2109	host_err = iterate_dir(file, &buf.ctx);
2110	if (buf.full)
2111	host_err = 0;
2112
2113	if (host_err < 0)
2114	break;
2115
2116	size = buf.used;
2117
2118	if (!size)
2119	break;
2120
2121	de = (struct buffered_dirent *)buf.dirent;
2122	while (size > 0) {
2123	offset = de->offset;
2124
2125	if (func(cdp, de->name, de->namlen, de->offset,
2126	de->ino, de->d_type))
2127	break;
2128
2129	if (cdp->err != nfs_ok)
2130	break;
2131
2132	trace_nfsd_dirent(fhp, ino: de->ino, name: de->name, namlen: de->namlen);
2133
2134	reclen = ALIGN(sizeof(*de) + de->namlen,
2135	sizeof(u64));
2136	size -= reclen;
2137	de = (struct buffered_dirent *)((char *)de + reclen);
2138	}
2139	if (size > 0) /* We bailed out early */
2140	break;
2141
2142	offset = vfs_llseek(file, offset: 0, SEEK_CUR);
2143	}
2144
2145	free_page((unsigned long)(buf.dirent));
2146
2147	if (host_err)
2148	return nfserrno(errno: host_err);
2149
2150	*offsetp = offset;
2151	return cdp->err;
2152	}
2153
2154	/**
2155	* nfsd_readdir - Read entries from a directory
2156	* @rqstp: RPC transaction context
2157	* @fhp: NFS file handle of directory to be read
2158	* @offsetp: OUT: seek offset of final entry that was read
2159	* @cdp: OUT: an eof error value
2160	* @func: entry filler actor
2161	*
2162	* This implementation ignores the NFSv3/4 verifier cookie.
2163	*
2164	* NB: normal system calls hold file->f_pos_lock when calling
2165	* ->iterate_shared and ->llseek, but nfsd_readdir() does not.
2166	* Because the struct file acquired here is not visible to other
2167	* threads, it's internal state does not need mutex protection.
2168	*
2169	* Returns nfs_ok on success, otherwise an nfsstat code is
2170	* returned.
2171	*/
2172	__be32
2173	nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
2174	struct readdir_cd *cdp, nfsd_filldir_t func)
2175	{
2176	__be32 err;
2177	struct file *file;
2178	loff_t offset = *offsetp;
2179	int may_flags = NFSD_MAY_READ;
2180
2181	/* NFSv2 only supports 32 bit cookies */
2182	if (rqstp->rq_vers > 2)
2183	may_flags |= NFSD_MAY_64BIT_COOKIE;
2184
2185	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, filp: &file);
2186	if (err)
2187	goto out;
2188
2189	offset = vfs_llseek(file, offset, SEEK_SET);
2190	if (offset < 0) {
2191	err = nfserrno(errno: (int)offset);
2192	goto out_close;
2193	}
2194
2195	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2196
2197	if (err == nfserr_eof || err == nfserr_toosmall)
2198	err = nfs_ok; /* can still be found in ->err */
2199	out_close:
2200	nfsd_filp_close(fp: file);
2201	out:
2202	return err;
2203	}
2204
2205	/**
2206	* nfsd_filp_close: close a file synchronously
2207	* @fp: the file to close
2208	*
2209	* nfsd_filp_close() is similar in behaviour to filp_close().
2210	* The difference is that if this is the final close on the
2211	* file, the that finalisation happens immediately, rather then
2212	* being handed over to a work_queue, as it the case for
2213	* filp_close().
2214	* When a user-space process closes a file (even when using
2215	* filp_close() the finalisation happens before returning to
2216	* userspace, so it is effectively synchronous. When a kernel thread
2217	* uses file_close(), on the other hand, the handling is completely
2218	* asynchronous. This means that any cost imposed by that finalisation
2219	* is not imposed on the nfsd thread, and nfsd could potentually
2220	* close files more quickly than the work queue finalises the close,
2221	* which would lead to unbounded growth in the queue.
2222	*
2223	* In some contexts is it not safe to synchronously wait for
2224	* close finalisation (see comment for __fput_sync()), but nfsd
2225	* does not match those contexts. In partcilarly it does not, at the
2226	* time that this function is called, hold and locks and no finalisation
2227	* of any file, socket, or device driver would have any cause to wait
2228	* for nfsd to make progress.
2229	*/
2230	void nfsd_filp_close(struct file *fp)
2231	{
2232	get_file(f: fp);
2233	filp_close(fp, NULL);
2234	__fput_sync(fp);
2235	}
2236
2237	/*
2238	* Get file system stats
2239	* N.B. After this call fhp needs an fh_put
2240	*/
2241	__be32
2242	nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2243	{
2244	__be32 err;
2245
2246	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2247	if (!err) {
2248	struct path path = {
2249	.mnt = fhp->fh_export->ex_path.mnt,
2250	.dentry = fhp->fh_dentry,
2251	};
2252	if (vfs_statfs(&path, stat))
2253	err = nfserr_io;
2254	}
2255	return err;
2256	}
2257
2258	static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
2259	{
2260	return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
2261	}
2262
2263	#ifdef CONFIG_NFSD_V4
2264	/*
2265	* Helper function to translate error numbers. In the case of xattr operations,
2266	* some error codes need to be translated outside of the standard translations.
2267	*
2268	* ENODATA needs to be translated to nfserr_noxattr.
2269	* E2BIG to nfserr_xattr2big.
2270	*
2271	* Additionally, vfs_listxattr can return -ERANGE. This means that the
2272	* file has too many extended attributes to retrieve inside an
2273	* XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2274	* filesystems will allow the adding of extended attributes until they hit
2275	* their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2276	* So, at that point, the attributes are present and valid, but can't
2277	* be retrieved using listxattr, since the upper level xattr code enforces
2278	* the XATTR_LIST_MAX limit.
2279	*
2280	* This bug means that we need to deal with listxattr returning -ERANGE. The
2281	* best mapping is to return TOOSMALL.
2282	*/
2283	static __be32
2284	nfsd_xattr_errno(int err)
2285	{
2286	switch (err) {
2287	case -ENODATA:
2288	return nfserr_noxattr;
2289	case -E2BIG:
2290	return nfserr_xattr2big;
2291	case -ERANGE:
2292	return nfserr_toosmall;
2293	}
2294	return nfserrno(errno: err);
2295	}
2296
2297	/*
2298	* Retrieve the specified user extended attribute. To avoid always
2299	* having to allocate the maximum size (since we are not getting
2300	* a maximum size from the RPC), do a probe + alloc. Hold a reader
2301	* lock on i_rwsem to prevent the extended attribute from changing
2302	* size while we're doing this.
2303	*/
2304	__be32
2305	nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2306	void **bufp, int *lenp)
2307	{
2308	ssize_t len;
2309	__be32 err;
2310	char *buf;
2311	struct inode *inode;
2312	struct dentry *dentry;
2313
2314	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2315	if (err)
2316	return err;
2317
2318	err = nfs_ok;
2319	dentry = fhp->fh_dentry;
2320	inode = d_inode(dentry);
2321
2322	inode_lock_shared(inode);
2323
2324	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, NULL, 0);
2325
2326	/*
2327	* Zero-length attribute, just return.
2328	*/
2329	if (len == 0) {
2330	*bufp = NULL;
2331	*lenp = 0;
2332	goto out;
2333	}
2334
2335	if (len < 0) {
2336	err = nfsd_xattr_errno(err: len);
2337	goto out;
2338	}
2339
2340	if (len > *lenp) {
2341	err = nfserr_toosmall;
2342	goto out;
2343	}
2344
2345	buf = kvmalloc(size: len, GFP_KERNEL);
2346	if (buf == NULL) {
2347	err = nfserr_jukebox;
2348	goto out;
2349	}
2350
2351	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, buf, len);
2352	if (len <= 0) {
2353	kvfree(addr: buf);
2354	buf = NULL;
2355	err = nfsd_xattr_errno(err: len);
2356	}
2357
2358	*lenp = len;
2359	*bufp = buf;
2360
2361	out:
2362	inode_unlock_shared(inode);
2363
2364	return err;
2365	}
2366
2367	/*
2368	* Retrieve the xattr names. Since we can't know how many are
2369	* user extended attributes, we must get all attributes here,
2370	* and have the XDR encode filter out the "user." ones.
2371	*
2372	* While this could always just allocate an XATTR_LIST_MAX
2373	* buffer, that's a waste, so do a probe + allocate. To
2374	* avoid any changes between the probe and allocate, wrap
2375	* this in inode_lock.
2376	*/
2377	__be32
2378	nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2379	int *lenp)
2380	{
2381	ssize_t len;
2382	__be32 err;
2383	char *buf;
2384	struct inode *inode;
2385	struct dentry *dentry;
2386
2387	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2388	if (err)
2389	return err;
2390
2391	dentry = fhp->fh_dentry;
2392	inode = d_inode(dentry);
2393	*lenp = 0;
2394
2395	inode_lock_shared(inode);
2396
2397	len = vfs_listxattr(d: dentry, NULL, size: 0);
2398	if (len <= 0) {
2399	err = nfsd_xattr_errno(err: len);
2400	goto out;
2401	}
2402
2403	if (len > XATTR_LIST_MAX) {
2404	err = nfserr_xattr2big;
2405	goto out;
2406	}
2407
2408	buf = kvmalloc(size: len, GFP_KERNEL);
2409	if (buf == NULL) {
2410	err = nfserr_jukebox;
2411	goto out;
2412	}
2413
2414	len = vfs_listxattr(d: dentry, list: buf, size: len);
2415	if (len <= 0) {
2416	kvfree(addr: buf);
2417	err = nfsd_xattr_errno(err: len);
2418	goto out;
2419	}
2420
2421	*lenp = len;
2422	*bufp = buf;
2423
2424	err = nfs_ok;
2425	out:
2426	inode_unlock_shared(inode);
2427
2428	return err;
2429	}
2430
2431	/**
2432	* nfsd_removexattr - Remove an extended attribute
2433	* @rqstp: RPC transaction being executed
2434	* @fhp: NFS filehandle of object with xattr to remove
2435	* @name: name of xattr to remove (NUL-terminate)
2436	*
2437	* Pass in a NULL pointer for delegated_inode, and let the client deal
2438	* with NFS4ERR_DELAY (same as with e.g. setattr and remove).
2439	*
2440	* Returns nfs_ok on success, or an nfsstat in network byte order.
2441	*/
2442	__be32
2443	nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2444	{
2445	__be32 err;
2446	int ret;
2447
2448	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2449	if (err)
2450	return err;
2451
2452	ret = fh_want_write(fh: fhp);
2453	if (ret)
2454	return nfserrno(errno: ret);
2455
2456	inode_lock(inode: fhp->fh_dentry->d_inode);
2457	err = fh_fill_pre_attrs(fhp);
2458	if (err != nfs_ok)
2459	goto out_unlock;
2460	ret = __vfs_removexattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
2461	name, NULL);
2462	err = nfsd_xattr_errno(err: ret);
2463	fh_fill_post_attrs(fhp);
2464	out_unlock:
2465	inode_unlock(inode: fhp->fh_dentry->d_inode);
2466	fh_drop_write(fh: fhp);
2467
2468	return err;
2469	}
2470
2471	__be32
2472	nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2473	void *buf, u32 len, u32 flags)
2474	{
2475	__be32 err;
2476	int ret;
2477
2478	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2479	if (err)
2480	return err;
2481
2482	ret = fh_want_write(fh: fhp);
2483	if (ret)
2484	return nfserrno(errno: ret);
2485	inode_lock(inode: fhp->fh_dentry->d_inode);
2486	err = fh_fill_pre_attrs(fhp);
2487	if (err != nfs_ok)
2488	goto out_unlock;
2489	ret = __vfs_setxattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
2490	name, buf, len, flags, NULL);
2491	fh_fill_post_attrs(fhp);
2492	err = nfsd_xattr_errno(err: ret);
2493	out_unlock:
2494	inode_unlock(inode: fhp->fh_dentry->d_inode);
2495	fh_drop_write(fh: fhp);
2496	return err;
2497	}
2498	#endif
2499
2500	/*
2501	* Check for a user's access permissions to this inode.
2502	*/
2503	__be32
2504	nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
2505	struct dentry *dentry, int acc)
2506	{
2507	struct inode *inode = d_inode(dentry);
2508	int err;
2509
2510	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2511	return 0;
2512	#if 0
2513	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2514	acc,
2515	(acc & NFSD_MAY_READ)? " read" : "",
2516	(acc & NFSD_MAY_WRITE)? " write" : "",
2517	(acc & NFSD_MAY_EXEC)? " exec" : "",
2518	(acc & NFSD_MAY_SATTR)? " sattr" : "",
2519	(acc & NFSD_MAY_TRUNC)? " trunc" : "",
2520	(acc & NFSD_MAY_LOCK)? " lock" : "",
2521	(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2522	inode->i_mode,
2523	IS_IMMUTABLE(inode)? " immut" : "",
2524	IS_APPEND(inode)? " append" : "",
2525	__mnt_is_readonly(exp->ex_path.mnt)? " ro" : "");
2526	dprintk(" owner %d/%d user %d/%d\n",
2527	inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2528	#endif
2529
2530	/* Normally we reject any write/sattr etc access on a read-only file
2531	* system. But if it is IRIX doing check on write-access for a
2532	* device special file, we ignore rofs.
2533	*/
2534	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2535	if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2536	if (exp_rdonly(rqstp, exp) ||
2537	__mnt_is_readonly(mnt: exp->ex_path.mnt))
2538	return nfserr_rofs;
2539	if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2540	return nfserr_perm;
2541	}
2542	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2543	return nfserr_perm;
2544
2545	if (acc & NFSD_MAY_LOCK) {
2546	/* If we cannot rely on authentication in NLM requests,
2547	* just allow locks, otherwise require read permission, or
2548	* ownership
2549	*/
2550	if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2551	return 0;
2552	else
2553	acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2554	}
2555	/*
2556	* The file owner always gets access permission for accesses that
2557	* would normally be checked at open time. This is to make
2558	* file access work even when the client has done a fchmod(fd, 0).
2559	*
2560	* However, `cp foo bar' should fail nevertheless when bar is
2561	* readonly. A sensible way to do this might be to reject all
2562	* attempts to truncate a read-only file, because a creat() call
2563	* always implies file truncation.
2564	* ... but this isn't really fair. A process may reasonably call
2565	* ftruncate on an open file descriptor on a file with perm 000.
2566	* We must trust the client to do permission checking - using "ACCESS"
2567	* with NFSv3.
2568	*/
2569	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2570	uid_eq(left: inode->i_uid, current_fsuid()))
2571	return 0;
2572
2573	/* This assumes NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2574	err = inode_permission(&nop_mnt_idmap, inode,
2575	acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2576
2577	/* Allow read access to binaries even when mode 111 */
2578	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2579	(acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2580	acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2581	err = inode_permission(&nop_mnt_idmap, inode, MAY_EXEC);
2582
2583	return err? nfserrno(errno: err) : 0;
2584	}
2585