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	#include <linux/sunrpc/xdr.h>
35
36	#include "xdr3.h"
37
38	#ifdef CONFIG_NFSD_V4
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	bool nfsd_disable_splice_read __read_mostly;
52	u64 nfsd_io_cache_read __read_mostly = NFSD_IO_BUFFERED;
53	u64 nfsd_io_cache_write __read_mostly = NFSD_IO_BUFFERED;
54
55	/**
56	* nfserrno - Map Linux errnos to NFS errnos
57	* @errno: POSIX(-ish) error code to be mapped
58	*
59	* Returns the appropriate (net-endian) nfserr_* (or nfs_ok if errno is 0). If
60	* it's an error we don't expect, log it once and return nfserr_io.
61	*/
62	__be32
63	nfserrno (int errno)
64	{
65	static struct {
66	__be32 nfserr;
67	int syserr;
68	} nfs_errtbl[] = {
69	{ nfs_ok, 0 },
70	{ nfserr_perm, -EPERM },
71	{ nfserr_noent, -ENOENT },
72	{ nfserr_io, -EIO },
73	{ nfserr_nxio, -ENXIO },
74	{ nfserr_fbig, -E2BIG },
75	{ nfserr_stale, -EBADF },
76	{ nfserr_acces, -EACCES },
77	{ nfserr_exist, -EEXIST },
78	{ nfserr_xdev, -EXDEV },
79	{ nfserr_nodev, -ENODEV },
80	{ nfserr_notdir, -ENOTDIR },
81	{ nfserr_isdir, -EISDIR },
82	{ nfserr_inval, -EINVAL },
83	{ nfserr_fbig, -EFBIG },
84	{ nfserr_nospc, -ENOSPC },
85	{ nfserr_rofs, -EROFS },
86	{ nfserr_mlink, -EMLINK },
87	{ nfserr_nametoolong, -ENAMETOOLONG },
88	{ nfserr_notempty, -ENOTEMPTY },
89	{ nfserr_dquot, -EDQUOT },
90	{ nfserr_stale, -ESTALE },
91	{ nfserr_jukebox, -ETIMEDOUT },
92	{ nfserr_jukebox, -ERESTARTSYS },
93	{ nfserr_jukebox, -EAGAIN },
94	{ nfserr_jukebox, -EWOULDBLOCK },
95	{ nfserr_jukebox, -ENOMEM },
96	{ nfserr_io, -ETXTBSY },
97	{ nfserr_notsupp, -EOPNOTSUPP },
98	{ nfserr_toosmall, -ETOOSMALL },
99	{ nfserr_serverfault, -ESERVERFAULT },
100	{ nfserr_serverfault, -ENFILE },
101	{ nfserr_io, -EREMOTEIO },
102	{ nfserr_stale, -EOPENSTALE },
103	{ nfserr_io, -EUCLEAN },
104	{ nfserr_perm, -ENOKEY },
105	{ nfserr_no_grace, -ENOGRACE},
106	{ nfserr_io, -EBADMSG },
107	};
108	int i;
109
110	for (i = 0; i < ARRAY_SIZE(nfs_errtbl); i++) {
111	if (nfs_errtbl[i].syserr == errno)
112	return nfs_errtbl[i].nfserr;
113	}
114	WARN_ONCE(1, "nfsd: non-standard errno: %d\n", errno);
115	return nfserr_io;
116	}
117
118	/*
119	* Called from nfsd_lookup and encode_dirent. Check if we have crossed
120	* a mount point.
121	* Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
122	* or nfs_ok having possibly changed *dpp and *expp
123	*/
124	int
125	nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp,
126	struct svc_export **expp)
127	{
128	struct svc_export *exp = *expp, *exp2 = NULL;
129	struct dentry *dentry = *dpp;
130	struct path path = {.mnt = mntget(mnt: exp->ex_path.mnt),
131	.dentry = dget(dentry)};
132	unsigned int follow_flags = 0;
133	int err = 0;
134
135	if (exp->ex_flags & NFSEXP_CROSSMOUNT)
136	follow_flags = LOOKUP_AUTOMOUNT;
137
138	err = follow_down(path: &path, flags: follow_flags);
139	if (err < 0)
140	goto out;
141	if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
142	nfsd_mountpoint(dentry, exp) == 2) {
143	/* This is only a mountpoint in some other namespace */
144	path_put(&path);
145	goto out;
146	}
147
148	exp2 = rqst_exp_get_by_name(rqstp, &path);
149	if (IS_ERR(ptr: exp2)) {
150	err = PTR_ERR(ptr: exp2);
151	/*
152	* We normally allow NFS clients to continue
153	* "underneath" a mountpoint that is not exported.
154	* The exception is V4ROOT, where no traversal is ever
155	* allowed without an explicit export of the new
156	* directory.
157	*/
158	if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
159	err = 0;
160	path_put(&path);
161	goto out;
162	}
163	if (nfsd_v4client(rq: rqstp) ||
164	(exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
165	/* successfully crossed mount point */
166	/*
167	* This is subtle: path.dentry is *not* on path.mnt
168	* at this point. The only reason we are safe is that
169	* original mnt is pinned down by exp, so we should
170	* put path *before* putting exp
171	*/
172	*dpp = path.dentry;
173	path.dentry = dentry;
174	*expp = exp2;
175	exp2 = exp;
176	}
177	path_put(&path);
178	exp_put(exp: exp2);
179	out:
180	return err;
181	}
182
183	static void follow_to_parent(struct path *path)
184	{
185	struct dentry *dp;
186
187	while (path->dentry == path->mnt->mnt_root && follow_up(path))
188	;
189	dp = dget_parent(dentry: path->dentry);
190	dput(path->dentry);
191	path->dentry = dp;
192	}
193
194	static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
195	{
196	struct svc_export *exp2;
197	struct path path = {.mnt = mntget(mnt: (*exp)->ex_path.mnt),
198	.dentry = dget(dentry: dparent)};
199
200	follow_to_parent(path: &path);
201
202	exp2 = rqst_exp_parent(rqstp, &path);
203	if (PTR_ERR(ptr: exp2) == -ENOENT) {
204	*dentryp = dget(dentry: dparent);
205	} else if (IS_ERR(ptr: exp2)) {
206	path_put(&path);
207	return PTR_ERR(ptr: exp2);
208	} else {
209	*dentryp = dget(dentry: path.dentry);
210	exp_put(exp: *exp);
211	*exp = exp2;
212	}
213	path_put(&path);
214	return 0;
215	}
216
217	/*
218	* For nfsd purposes, we treat V4ROOT exports as though there was an
219	* export at *every* directory.
220	* We return:
221	* '1' if this dentry *must* be an export point,
222	* '2' if it might be, if there is really a mount here, and
223	* '0' if there is no chance of an export point here.
224	*/
225	int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
226	{
227	if (!d_inode(dentry))
228	return 0;
229	if (exp->ex_flags & NFSEXP_V4ROOT)
230	return 1;
231	if (nfsd4_is_junction(dentry))
232	return 1;
233	if (d_managed(dentry))
234	/*
235	* Might only be a mountpoint in a different namespace,
236	* but we need to check.
237	*/
238	return 2;
239	return 0;
240	}
241
242	__be32
243	nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
244	const char *name, unsigned int len,
245	struct svc_export **exp_ret, struct dentry **dentry_ret)
246	{
247	struct svc_export *exp;
248	struct dentry *dparent;
249	struct dentry *dentry;
250	int host_err;
251
252	trace_nfsd_vfs_lookup(rqstp, fhp, name, len);
253
254	dparent = fhp->fh_dentry;
255	exp = exp_get(exp: fhp->fh_export);
256
257	/* Lookup the name, but don't follow links */
258	if (isdotent(name, len)) {
259	if (len==1)
260	dentry = dget(dentry: dparent);
261	else if (dparent != exp->ex_path.dentry)
262	dentry = dget_parent(dentry: dparent);
263	else if (!EX_NOHIDE(exp) && !nfsd_v4client(rq: rqstp))
264	dentry = dget(dentry: dparent); /* .. == . just like at / */
265	else {
266	/* checking mountpoint crossing is very different when stepping up */
267	host_err = nfsd_lookup_parent(rqstp, dparent, exp: &exp, dentryp: &dentry);
268	if (host_err)
269	goto out_nfserr;
270	}
271	} else {
272	dentry = lookup_one_unlocked(idmap: &nop_mnt_idmap,
273	name: &QSTR_LEN(name, len), base: dparent);
274	host_err = PTR_ERR(ptr: dentry);
275	if (IS_ERR(ptr: dentry))
276	goto out_nfserr;
277	if (nfsd_mountpoint(dentry, exp)) {
278	host_err = nfsd_cross_mnt(rqstp, dpp: &dentry, expp: &exp);
279	if (host_err) {
280	dput(dentry);
281	goto out_nfserr;
282	}
283	}
284	}
285	*dentry_ret = dentry;
286	*exp_ret = exp;
287	return 0;
288
289	out_nfserr:
290	exp_put(exp);
291	return nfserrno(errno: host_err);
292	}
293
294	/**
295	* nfsd_lookup - look up a single path component for nfsd
296	*
297	* @rqstp: the request context
298	* @fhp: the file handle of the directory
299	* @name: the component name, or %NULL to look up parent
300	* @len: length of name to examine
301	* @resfh: pointer to pre-initialised filehandle to hold result.
302	*
303	* Look up one component of a pathname.
304	* N.B. After this call _both_ fhp and resfh need an fh_put
305	*
306	* If the lookup would cross a mountpoint, and the mounted filesystem
307	* is exported to the client with NFSEXP_NOHIDE, then the lookup is
308	* accepted as it stands and the mounted directory is
309	* returned. Otherwise the covered directory is returned.
310	* NOTE: this mountpoint crossing is not supported properly by all
311	* clients and is explicitly disallowed for NFSv3
312	*
313	*/
314	__be32
315	nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
316	unsigned int len, struct svc_fh *resfh)
317	{
318	struct svc_export *exp;
319	struct dentry *dentry;
320	__be32 err;
321
322	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
323	if (err)
324	return err;
325	err = nfsd_lookup_dentry(rqstp, fhp, name, len, exp_ret: &exp, dentry_ret: &dentry);
326	if (err)
327	return err;
328	err = check_nfsd_access(exp, rqstp, may_bypass_gss: false);
329	if (err)
330	goto out;
331	/*
332	* Note: we compose the file handle now, but as the
333	* dentry may be negative, it may need to be updated.
334	*/
335	err = fh_compose(resfh, exp, dentry, fhp);
336	if (!err && d_really_is_negative(dentry))
337	err = nfserr_noent;
338	out:
339	dput(dentry);
340	exp_put(exp);
341	return err;
342	}
343
344	static void
345	commit_reset_write_verifier(struct nfsd_net *nn, struct svc_rqst *rqstp,
346	int err)
347	{
348	switch (err) {
349	case -EAGAIN:
350	case -ESTALE:
351	/*
352	* Neither of these are the result of a problem with
353	* durable storage, so avoid a write verifier reset.
354	*/
355	break;
356	default:
357	nfsd_reset_write_verifier(nn);
358	trace_nfsd_writeverf_reset(nn, rqstp, error: err);
359	}
360	}
361
362	/*
363	* Commit metadata changes to stable storage.
364	*/
365	static int
366	commit_inode_metadata(struct inode *inode)
367	{
368	const struct export_operations *export_ops = inode->i_sb->s_export_op;
369
370	if (export_ops->commit_metadata)
371	return export_ops->commit_metadata(inode);
372	return sync_inode_metadata(inode, wait: 1);
373	}
374
375	static int
376	commit_metadata(struct svc_fh *fhp)
377	{
378	struct inode *inode = d_inode(dentry: fhp->fh_dentry);
379
380	if (!EX_ISSYNC(fhp->fh_export))
381	return 0;
382	return commit_inode_metadata(inode);
383	}
384
385	/*
386	* Go over the attributes and take care of the small differences between
387	* NFS semantics and what Linux expects.
388	*/
389	static void
390	nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
391	{
392	/* Ignore mode updates on symlinks */
393	if (S_ISLNK(inode->i_mode))
394	iap->ia_valid &= ~ATTR_MODE;
395
396	/* sanitize the mode change */
397	if (iap->ia_valid & ATTR_MODE) {
398	iap->ia_mode &= S_IALLUGO;
399	iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
400	}
401
402	/* Revoke setuid/setgid on chown */
403	if (!S_ISDIR(inode->i_mode) &&
404	((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
405	iap->ia_valid |= ATTR_KILL_PRIV;
406	if (iap->ia_valid & ATTR_MODE) {
407	/* we're setting mode too, just clear the s*id bits */
408	iap->ia_mode &= ~S_ISUID;
409	if (iap->ia_mode & S_IXGRP)
410	iap->ia_mode &= ~S_ISGID;
411	} else {
412	/* set ATTR_KILL_* bits and let VFS handle it */
413	iap->ia_valid |= ATTR_KILL_SUID;
414	iap->ia_valid |=
415	setattr_should_drop_sgid(idmap: &nop_mnt_idmap, inode);
416	}
417	}
418	}
419
420	static __be32
421	nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
422	struct iattr *iap)
423	{
424	struct inode *inode = d_inode(dentry: fhp->fh_dentry);
425
426	if (iap->ia_size < inode->i_size) {
427	__be32 err;
428
429	err = nfsd_permission(cred: &rqstp->rq_cred,
430	exp: fhp->fh_export, dentry: fhp->fh_dentry,
431	NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
432	if (err)
433	return err;
434	}
435	return nfserrno(errno: get_write_access(inode));
436	}
437
438	static int __nfsd_setattr(struct dentry *dentry, struct iattr *iap)
439	{
440	int host_err;
441
442	if (iap->ia_valid & ATTR_SIZE) {
443	/*
444	* RFC5661, Section 18.30.4:
445	* Changing the size of a file with SETATTR indirectly
446	* changes the time_modify and change attributes.
447	*
448	* (and similar for the older RFCs)
449	*/
450	struct iattr size_attr = {
451	.ia_valid = ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
452	.ia_size = iap->ia_size,
453	};
454
455	if (iap->ia_size < 0)
456	return -EFBIG;
457
458	host_err = notify_change(&nop_mnt_idmap, dentry, &size_attr, NULL);
459	if (host_err)
460	return host_err;
461	iap->ia_valid &= ~ATTR_SIZE;
462
463	/*
464	* Avoid the additional setattr call below if the only other
465	* attribute that the client sends is the mtime, as we update
466	* it as part of the size change above.
467	*/
468	if ((iap->ia_valid & ~ATTR_MTIME) == 0)
469	return 0;
470	}
471
472	if ((iap->ia_valid & ~ATTR_DELEG) == 0)
473	return 0;
474
475	/*
476	* If ATTR_DELEG is set, then this is an update from a client that
477	* holds a delegation. If this is an update for only the atime, the
478	* ctime should not be changed. If the update contains the mtime
479	* too, then ATTR_CTIME should already be set.
480	*/
481	if (!(iap->ia_valid & ATTR_DELEG))
482	iap->ia_valid |= ATTR_CTIME;
483
484	return notify_change(&nop_mnt_idmap, dentry, iap, NULL);
485	}
486
487	/**
488	* nfsd_setattr - Set various file attributes.
489	* @rqstp: controlling RPC transaction
490	* @fhp: filehandle of target
491	* @attr: attributes to set
492	* @guardtime: do not act if ctime.tv_sec does not match this timestamp
493	*
494	* This call may adjust the contents of @attr (in particular, this
495	* call may change the bits in the na_iattr.ia_valid field).
496	*
497	* Returns nfs_ok on success, otherwise an NFS status code is
498	* returned. Caller must release @fhp by calling fh_put in either
499	* case.
500	*/
501	__be32
502	nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
503	struct nfsd_attrs *attr, const struct timespec64 *guardtime)
504	{
505	struct dentry *dentry;
506	struct inode *inode;
507	struct iattr *iap = attr->na_iattr;
508	int accmode = NFSD_MAY_SATTR;
509	umode_t ftype = 0;
510	__be32 err;
511	int host_err = 0;
512	bool get_write_count;
513	bool size_change = (iap->ia_valid & ATTR_SIZE);
514	int retries;
515
516	trace_nfsd_vfs_setattr(rqstp, fhp, iap, guardtime);
517
518	if (iap->ia_valid & ATTR_SIZE) {
519	accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
520	ftype = S_IFREG;
521	}
522
523	/*
524	* If utimes(2) and friends are called with times not NULL, we should
525	* not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
526	* will return EACCES, when the caller's effective UID does not match
527	* the owner of the file, and the caller is not privileged. In this
528	* situation, we should return EPERM(notify_change will return this).
529	*/
530	if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
531	accmode |= NFSD_MAY_OWNER_OVERRIDE;
532	if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
533	accmode |= NFSD_MAY_WRITE;
534	}
535
536	/* Callers that do fh_verify should do the fh_want_write: */
537	get_write_count = !fhp->fh_dentry;
538
539	/* Get inode */
540	err = fh_verify(rqstp, fhp, ftype, accmode);
541	if (err)
542	return err;
543	if (get_write_count) {
544	host_err = fh_want_write(fhp);
545	if (host_err)
546	goto out;
547	}
548
549	dentry = fhp->fh_dentry;
550	inode = d_inode(dentry);
551
552	nfsd_sanitize_attrs(inode, iap);
553
554	/*
555	* The size case is special, it changes the file in addition to the
556	* attributes, and file systems don't expect it to be mixed with
557	* "random" attribute changes. We thus split out the size change
558	* into a separate call to ->setattr, and do the rest as a separate
559	* setattr call.
560	*/
561	if (size_change) {
562	err = nfsd_get_write_access(rqstp, fhp, iap);
563	if (err)
564	return err;
565	}
566
567	inode_lock(inode);
568	err = fh_fill_pre_attrs(fhp);
569	if (err)
570	goto out_unlock;
571
572	if (guardtime) {
573	struct timespec64 ctime = inode_get_ctime(inode);
574	if ((u32)guardtime->tv_sec != (u32)ctime.tv_sec ||
575	guardtime->tv_nsec != ctime.tv_nsec) {
576	err = nfserr_notsync;
577	goto out_fill_attrs;
578	}
579	}
580
581	for (retries = 1;;) {
582	struct iattr attrs;
583
584	/*
585	* notify_change() can alter its iattr argument, making
586	* @iap unsuitable for submission multiple times. Make a
587	* copy for every loop iteration.
588	*/
589	attrs = *iap;
590	host_err = __nfsd_setattr(dentry, iap: &attrs);
591	if (host_err != -EAGAIN || !retries--)
592	break;
593	if (!nfsd_wait_for_delegreturn(rqstp, inode))
594	break;
595	}
596	if (attr->na_seclabel && attr->na_seclabel->len)
597	attr->na_labelerr = security_inode_setsecctx(dentry,
598	ctx: attr->na_seclabel->data, ctxlen: attr->na_seclabel->len);
599	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl)
600	attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
601	dentry, ACL_TYPE_ACCESS,
602	attr->na_pacl);
603	if (IS_ENABLED(CONFIG_FS_POSIX_ACL) &&
604	!attr->na_aclerr && attr->na_dpacl && S_ISDIR(inode->i_mode))
605	attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
606	dentry, ACL_TYPE_DEFAULT,
607	attr->na_dpacl);
608	out_fill_attrs:
609	/*
610	* RFC 1813 Section 3.3.2 does not mandate that an NFS server
611	* returns wcc_data for SETATTR. Some client implementations
612	* depend on receiving wcc_data, however, to sort out partial
613	* updates (eg., the client requested that size and mode be
614	* modified, but the server changed only the file mode).
615	*/
616	fh_fill_post_attrs(fhp);
617	out_unlock:
618	inode_unlock(inode);
619	if (size_change)
620	put_write_access(inode);
621	out:
622	if (!host_err)
623	host_err = commit_metadata(fhp);
624	return err != 0 ? err : nfserrno(errno: host_err);
625	}
626
627	#if defined(CONFIG_NFSD_V4)
628	/*
629	* NFS junction information is stored in an extended attribute.
630	*/
631	#define NFSD_JUNCTION_XATTR_NAME XATTR_TRUSTED_PREFIX "junction.nfs"
632
633	/**
634	* nfsd4_is_junction - Test if an object could be an NFS junction
635	*
636	* @dentry: object to test
637	*
638	* Returns 1 if "dentry" appears to contain NFS junction information.
639	* Otherwise 0 is returned.
640	*/
641	int nfsd4_is_junction(struct dentry *dentry)
642	{
643	struct inode *inode = d_inode(dentry);
644
645	if (inode == NULL)
646	return 0;
647	if (inode->i_mode & S_IXUGO)
648	return 0;
649	if (!(inode->i_mode & S_ISVTX))
650	return 0;
651	if (vfs_getxattr(&nop_mnt_idmap, dentry, NFSD_JUNCTION_XATTR_NAME,
652	NULL, 0) <= 0)
653	return 0;
654	return 1;
655	}
656
657	static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
658	{
659	return &((struct nfsd4_compoundres *)rqstp->rq_resp)->cstate;
660	}
661
662	__be32 nfsd4_clone_file_range(struct svc_rqst *rqstp,
663	struct nfsd_file *nf_src, u64 src_pos,
664	struct nfsd_file *nf_dst, u64 dst_pos,
665	u64 count, bool sync)
666	{
667	struct file *src = nf_src->nf_file;
668	struct file *dst = nf_dst->nf_file;
669	errseq_t since;
670	loff_t cloned;
671	__be32 ret = 0;
672
673	since = READ_ONCE(dst->f_wb_err);
674	cloned = vfs_clone_file_range(file_in: src, pos_in: src_pos, file_out: dst, pos_out: dst_pos, len: count, remap_flags: 0);
675	if (cloned < 0) {
676	ret = nfserrno(errno: cloned);
677	goto out_err;
678	}
679	if (count && cloned != count) {
680	ret = nfserrno(errno: -EINVAL);
681	goto out_err;
682	}
683	if (sync) {
684	loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
685	int status = vfs_fsync_range(file: dst, start: dst_pos, end: dst_end, datasync: 0);
686
687	if (!status)
688	status = filemap_check_wb_err(mapping: dst->f_mapping, since);
689	if (!status)
690	status = commit_inode_metadata(inode: file_inode(f: src));
691	if (status < 0) {
692	struct nfsd_net *nn = net_generic(net: nf_dst->nf_net,
693	id: nfsd_net_id);
694
695	trace_nfsd_clone_file_range_err(rqstp,
696	src_fhp: &nfsd4_get_cstate(rqstp)->save_fh,
697	src_offset: src_pos,
698	dst_fhp: &nfsd4_get_cstate(rqstp)->current_fh,
699	dst_offset: dst_pos,
700	count, status);
701	commit_reset_write_verifier(nn, rqstp, err: status);
702	ret = nfserrno(errno: status);
703	}
704	}
705	out_err:
706	return ret;
707	}
708
709	ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
710	u64 dst_pos, u64 count)
711	{
712	ssize_t ret;
713
714	/*
715	* Limit copy to 4MB to prevent indefinitely blocking an nfsd
716	* thread and client rpc slot. The choice of 4MB is somewhat
717	* arbitrary. We might instead base this on r/wsize, or make it
718	* tunable, or use a time instead of a byte limit, or implement
719	* asynchronous copy. In theory a client could also recognize a
720	* limit like this and pipeline multiple COPY requests.
721	*/
722	count = min_t(u64, count, 1 << 22);
723	ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
724
725	if (ret == -EOPNOTSUPP || ret == -EXDEV)
726	ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count,
727	COPY_FILE_SPLICE);
728	return ret;
729	}
730
731	__be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
732	struct file *file, loff_t offset, loff_t len,
733	int flags)
734	{
735	int error;
736
737	if (!S_ISREG(file_inode(file)->i_mode))
738	return nfserr_inval;
739
740	error = vfs_fallocate(file, mode: flags, offset, len);
741	if (!error)
742	error = commit_metadata(fhp);
743
744	return nfserrno(errno: error);
745	}
746	#endif /* defined(CONFIG_NFSD_V4) */
747
748	/*
749	* Check server access rights to a file system object
750	*/
751	struct accessmap {
752	u32 access;
753	int how;
754	};
755	static struct accessmap nfs3_regaccess[] = {
756	{ NFS3_ACCESS_READ, NFSD_MAY_READ },
757	{ NFS3_ACCESS_EXECUTE, NFSD_MAY_EXEC },
758	{ NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_TRUNC },
759	{ NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE },
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_diraccess[] = {
771	{ NFS3_ACCESS_READ, NFSD_MAY_READ },
772	{ NFS3_ACCESS_LOOKUP, NFSD_MAY_EXEC },
773	{ NFS3_ACCESS_MODIFY, NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
774	{ NFS3_ACCESS_EXTEND, NFSD_MAY_EXEC|NFSD_MAY_WRITE },
775	{ NFS3_ACCESS_DELETE, NFSD_MAY_REMOVE },
776
777	#ifdef CONFIG_NFSD_V4
778	{ NFS4_ACCESS_XAREAD, NFSD_MAY_READ },
779	{ NFS4_ACCESS_XAWRITE, NFSD_MAY_WRITE },
780	{ NFS4_ACCESS_XALIST, NFSD_MAY_READ },
781	#endif
782
783	{ 0, 0 }
784	};
785
786	static struct accessmap nfs3_anyaccess[] = {
787	/* Some clients - Solaris 2.6 at least, make an access call
788	* to the server to check for access for things like /dev/null
789	* (which really, the server doesn't care about). So
790	* We provide simple access checking for them, looking
791	* mainly at mode bits, and we make sure to ignore read-only
792	* filesystem checks
793	*/
794	{ NFS3_ACCESS_READ, NFSD_MAY_READ },
795	{ NFS3_ACCESS_EXECUTE, NFSD_MAY_EXEC },
796	{ NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS },
797	{ NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS },
798
799	{ 0, 0 }
800	};
801
802	__be32
803	nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
804	{
805	struct accessmap *map;
806	struct svc_export *export;
807	struct dentry *dentry;
808	u32 query, result = 0, sresult = 0;
809	__be32 error;
810
811	error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
812	if (error)
813	goto out;
814
815	export = fhp->fh_export;
816	dentry = fhp->fh_dentry;
817
818	if (d_is_reg(dentry))
819	map = nfs3_regaccess;
820	else if (d_is_dir(dentry))
821	map = nfs3_diraccess;
822	else
823	map = nfs3_anyaccess;
824
825
826	query = *access;
827	for (; map->access; map++) {
828	if (map->access & query) {
829	__be32 err2;
830
831	sresult |= map->access;
832
833	err2 = nfsd_permission(cred: &rqstp->rq_cred, exp: export,
834	dentry, acc: map->how);
835	switch (err2) {
836	case nfs_ok:
837	result |= map->access;
838	break;
839
840	/* the following error codes just mean the access was not allowed,
841	* rather than an error occurred */
842	case nfserr_rofs:
843	case nfserr_acces:
844	case nfserr_perm:
845	/* simply don't "or" in the access bit. */
846	break;
847	default:
848	error = err2;
849	goto out;
850	}
851	}
852	}
853	*access = result;
854	if (supported)
855	*supported = sresult;
856
857	out:
858	return error;
859	}
860
861	int nfsd_open_break_lease(struct inode *inode, int access)
862	{
863	unsigned int mode;
864
865	if (access & NFSD_MAY_NOT_BREAK_LEASE)
866	return 0;
867	mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
868	return break_lease(inode, mode: mode | O_NONBLOCK);
869	}
870
871	/*
872	* Open an existing file or directory.
873	* The may_flags argument indicates the type of open (read/write/lock)
874	* and additional flags.
875	* N.B. After this call fhp needs an fh_put
876	*/
877	static int
878	__nfsd_open(struct svc_fh *fhp, umode_t type, int may_flags, struct file **filp)
879	{
880	struct path path;
881	struct inode *inode;
882	struct file *file;
883	int flags = O_RDONLY|O_LARGEFILE;
884	int host_err = -EPERM;
885
886	path.mnt = fhp->fh_export->ex_path.mnt;
887	path.dentry = fhp->fh_dentry;
888	inode = d_inode(dentry: path.dentry);
889
890	if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
891	goto out;
892
893	if (!inode->i_fop)
894	goto out;
895
896	host_err = nfsd_open_break_lease(inode, access: may_flags);
897	if (host_err) /* NOMEM or WOULDBLOCK */
898	goto out;
899
900	if (may_flags & NFSD_MAY_WRITE) {
901	if (may_flags & NFSD_MAY_READ)
902	flags = O_RDWR|O_LARGEFILE;
903	else
904	flags = O_WRONLY|O_LARGEFILE;
905	}
906
907	file = dentry_open(path: &path, flags, current_cred());
908	if (IS_ERR(ptr: file)) {
909	host_err = PTR_ERR(ptr: file);
910	goto out;
911	}
912
913	host_err = security_file_post_open(file, mask: may_flags);
914	if (host_err) {
915	fput(file);
916	goto out;
917	}
918
919	*filp = file;
920	out:
921	return host_err;
922	}
923
924	__be32
925	nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
926	int may_flags, struct file **filp)
927	{
928	__be32 err;
929	int host_err;
930	bool retried = false;
931
932	/*
933	* If we get here, then the client has already done an "open",
934	* and (hopefully) checked permission - so allow OWNER_OVERRIDE
935	* in case a chmod has now revoked permission.
936	*
937	* Arguably we should also allow the owner override for
938	* directories, but we never have and it doesn't seem to have
939	* caused anyone a problem. If we were to change this, note
940	* also that our filldir callbacks would need a variant of
941	* lookup_one_positive_unlocked() that doesn't check permissions.
942	*/
943	if (type == S_IFREG)
944	may_flags |= NFSD_MAY_OWNER_OVERRIDE;
945	retry:
946	err = fh_verify(rqstp, fhp, type, may_flags);
947	if (!err) {
948	host_err = __nfsd_open(fhp, type, may_flags, filp);
949	if (host_err == -EOPENSTALE && !retried) {
950	retried = true;
951	fh_put(fhp);
952	goto retry;
953	}
954	err = nfserrno(errno: host_err);
955	}
956	return err;
957	}
958
959	/**
960	* nfsd_open_verified - Open a regular file for the filecache
961	* @fhp: NFS filehandle of the file to open
962	* @type: S_IFMT inode type allowed (0 means any type is allowed)
963	* @may_flags: internal permission flags
964	* @filp: OUT: open "struct file *"
965	*
966	* Returns zero on success, or a negative errno value.
967	*/
968	int
969	nfsd_open_verified(struct svc_fh *fhp, umode_t type, int may_flags, struct file **filp)
970	{
971	return __nfsd_open(fhp, type, may_flags, filp);
972	}
973
974	/*
975	* Grab and keep cached pages associated with a file in the svc_rqst
976	* so that they can be passed to the network sendmsg routines
977	* directly. They will be released after the sending has completed.
978	*
979	* Return values: Number of bytes consumed, or -EIO if there are no
980	* remaining pages in rqstp->rq_pages.
981	*/
982	static int
983	nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
984	struct splice_desc *sd)
985	{
986	struct svc_rqst *rqstp = sd->u.data;
987	struct page *page = buf->page; // may be a compound one
988	unsigned offset = buf->offset;
989	struct page *last_page;
990
991	last_page = page + (offset + sd->len - 1) / PAGE_SIZE;
992	for (page += offset / PAGE_SIZE; page <= last_page; page++) {
993	/*
994	* Skip page replacement when extending the contents of the
995	* current page. But note that we may get two zero_pages in a
996	* row from shmem.
997	*/
998	if (page == *(rqstp->rq_next_page - 1) &&
999	offset_in_page(rqstp->rq_res.page_base +
1000	rqstp->rq_res.page_len))
1001	continue;
1002	if (unlikely(!svc_rqst_replace_page(rqstp, page)))
1003	return -EIO;
1004	}
1005	if (rqstp->rq_res.page_len == 0) // first call
1006	rqstp->rq_res.page_base = offset % PAGE_SIZE;
1007	rqstp->rq_res.page_len += sd->len;
1008	return sd->len;
1009	}
1010
1011	static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
1012	struct splice_desc *sd)
1013	{
1014	return __splice_from_pipe(pipe, sd, actor: nfsd_splice_actor);
1015	}
1016
1017	static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
1018	size_t expected)
1019	{
1020	if (expected != 0 && len == 0)
1021	return 1;
1022	if (offset+len >= i_size_read(inode: file_inode(f: file)))
1023	return 1;
1024	return 0;
1025	}
1026
1027	static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1028	struct file *file, loff_t offset,
1029	unsigned long *count, u32 *eof, ssize_t host_err)
1030	{
1031	if (host_err >= 0) {
1032	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), id: nfsd_net_id);
1033
1034	nfsd_stats_io_read_add(nn, exp: fhp->fh_export, amount: host_err);
1035	*eof = nfsd_eof_on_read(file, offset, len: host_err, expected: *count);
1036	*count = host_err;
1037	fsnotify_access(file);
1038	trace_nfsd_read_io_done(rqstp, fhp, offset, len: *count);
1039	return 0;
1040	} else {
1041	trace_nfsd_read_err(rqstp, fhp, offset, len: host_err);
1042	return nfserrno(errno: host_err);
1043	}
1044	}
1045
1046	/**
1047	* nfsd_splice_read - Perform a VFS read using a splice pipe
1048	* @rqstp: RPC transaction context
1049	* @fhp: file handle of file to be read
1050	* @file: opened struct file of file to be read
1051	* @offset: starting byte offset
1052	* @count: IN: requested number of bytes; OUT: number of bytes read
1053	* @eof: OUT: set non-zero if operation reached the end of the file
1054	*
1055	* Returns nfs_ok on success, otherwise an nfserr stat value is
1056	* returned.
1057	*/
1058	__be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1059	struct file *file, loff_t offset, unsigned long *count,
1060	u32 *eof)
1061	{
1062	struct splice_desc sd = {
1063	.len = 0,
1064	.total_len = *count,
1065	.pos = offset,
1066	.u.data = rqstp,
1067	};
1068	ssize_t host_err;
1069
1070	trace_nfsd_read_splice(rqstp, fhp, offset, len: *count);
1071	host_err = rw_verify_area(READ, file, &offset, *count);
1072	if (!host_err)
1073	host_err = splice_direct_to_actor(file, sd: &sd,
1074	actor: nfsd_direct_splice_actor);
1075	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
1076	}
1077
1078	/*
1079	* The byte range of the client's READ request is expanded on both ends
1080	* until it meets the underlying file system's direct I/O alignment
1081	* requirements. After the internal read is complete, the byte range of
1082	* the NFS READ payload is reduced to the byte range that was originally
1083	* requested.
1084	*
1085	* Note that a direct read can be done only when the xdr_buf containing
1086	* the NFS READ reply does not already have contents in its .pages array.
1087	* This is due to potentially restrictive alignment requirements on the
1088	* read buffer. When .page_len and @base are zero, the .pages array is
1089	* guaranteed to be page-aligned.
1090	*/
1091	static noinline_for_stack __be32
1092	nfsd_direct_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1093	struct nfsd_file *nf, loff_t offset, unsigned long *count,
1094	u32 *eof)
1095	{
1096	u64 dio_start, dio_end;
1097	unsigned long v, total;
1098	struct iov_iter iter;
1099	struct kiocb kiocb;
1100	ssize_t host_err;
1101	size_t len;
1102
1103	init_sync_kiocb(kiocb: &kiocb, filp: nf->nf_file);
1104	kiocb.ki_flags |= IOCB_DIRECT;
1105
1106	/* Read a properly-aligned region of bytes into rq_bvec */
1107	dio_start = round_down(offset, nf->nf_dio_read_offset_align);
1108	dio_end = round_up((u64)offset + *count, nf->nf_dio_read_offset_align);
1109
1110	kiocb.ki_pos = dio_start;
1111
1112	v = 0;
1113	total = dio_end - dio_start;
1114	while (total && v < rqstp->rq_maxpages &&
1115	rqstp->rq_next_page < rqstp->rq_page_end) {
1116	len = min_t(size_t, total, PAGE_SIZE);
1117	bvec_set_page(bv: &rqstp->rq_bvec[v], page: *rqstp->rq_next_page,
1118	len, offset: 0);
1119
1120	total -= len;
1121	++rqstp->rq_next_page;
1122	++v;
1123	}
1124
1125	trace_nfsd_read_direct(rqstp, fhp, offset, len: *count - total);
1126	iov_iter_bvec(i: &iter, ITER_DEST, bvec: rqstp->rq_bvec, nr_segs: v,
1127	count: dio_end - dio_start - total);
1128
1129	host_err = vfs_iocb_iter_read(file: nf->nf_file, iocb: &kiocb, iter: &iter);
1130	if (host_err >= 0) {
1131	unsigned int pad = offset - dio_start;
1132
1133	/* The returned payload starts after the pad */
1134	rqstp->rq_res.page_base = pad;
1135
1136	/* Compute the count of bytes to be returned */
1137	if (host_err > pad + *count)
1138	host_err = *count;
1139	else if (host_err > pad)
1140	host_err -= pad;
1141	else
1142	host_err = 0;
1143	} else if (unlikely(host_err == -EINVAL)) {
1144	struct inode *inode = d_inode(dentry: fhp->fh_dentry);
1145
1146	pr_info_ratelimited("nfsd: Direct I/O alignment failure on %s/%ld\n",
1147	inode->i_sb->s_id, inode->i_ino);
1148	host_err = -ESERVERFAULT;
1149	}
1150
1151	return nfsd_finish_read(rqstp, fhp, file: nf->nf_file, offset, count,
1152	eof, host_err);
1153	}
1154
1155	/**
1156	* nfsd_iter_read - Perform a VFS read using an iterator
1157	* @rqstp: RPC transaction context
1158	* @fhp: file handle of file to be read
1159	* @nf: opened struct nfsd_file of file to be read
1160	* @offset: starting byte offset
1161	* @count: IN: requested number of bytes; OUT: number of bytes read
1162	* @base: offset in first page of read buffer
1163	* @eof: OUT: set non-zero if operation reached the end of the file
1164	*
1165	* Some filesystems or situations cannot use nfsd_splice_read. This
1166	* function is the slightly less-performant fallback for those cases.
1167	*
1168	* Returns nfs_ok on success, otherwise an nfserr stat value is
1169	* returned.
1170	*/
1171	__be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1172	struct nfsd_file *nf, loff_t offset, unsigned long *count,
1173	unsigned int base, u32 *eof)
1174	{
1175	struct file *file = nf->nf_file;
1176	unsigned long v, total;
1177	struct iov_iter iter;
1178	struct kiocb kiocb;
1179	ssize_t host_err;
1180	size_t len;
1181
1182	init_sync_kiocb(kiocb: &kiocb, filp: file);
1183
1184	switch (nfsd_io_cache_read) {
1185	case NFSD_IO_BUFFERED:
1186	break;
1187	case NFSD_IO_DIRECT:
1188	/* When dio_read_offset_align is zero, dio is not supported */
1189	if (nf->nf_dio_read_offset_align && !rqstp->rq_res.page_len)
1190	return nfsd_direct_read(rqstp, fhp, nf, offset,
1191	count, eof);
1192	fallthrough;
1193	case NFSD_IO_DONTCACHE:
1194	if (file->f_op->fop_flags & FOP_DONTCACHE)
1195	kiocb.ki_flags = IOCB_DONTCACHE;
1196	break;
1197	}
1198
1199	kiocb.ki_pos = offset;
1200
1201	v = 0;
1202	total = *count;
1203	while (total && v < rqstp->rq_maxpages &&
1204	rqstp->rq_next_page < rqstp->rq_page_end) {
1205	len = min_t(size_t, total, PAGE_SIZE - base);
1206	bvec_set_page(bv: &rqstp->rq_bvec[v], page: *rqstp->rq_next_page,
1207	len, offset: base);
1208
1209	total -= len;
1210	++rqstp->rq_next_page;
1211	++v;
1212	base = 0;
1213	}
1214
1215	trace_nfsd_read_vector(rqstp, fhp, offset, len: *count - total);
1216	iov_iter_bvec(i: &iter, ITER_DEST, bvec: rqstp->rq_bvec, nr_segs: v, count: *count - total);
1217	host_err = vfs_iocb_iter_read(file, iocb: &kiocb, iter: &iter);
1218	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
1219	}
1220
1221	/*
1222	* Gathered writes: If another process is currently writing to the file,
1223	* there's a high chance this is another nfsd (triggered by a bulk write
1224	* from a client's biod). Rather than syncing the file with each write
1225	* request, we sleep for 10 msec.
1226	*
1227	* I don't know if this roughly approximates C. Juszak's idea of
1228	* gathered writes, but it's a nice and simple solution (IMHO), and it
1229	* seems to work:-)
1230	*
1231	* Note: we do this only in the NFSv2 case, since v3 and higher have a
1232	* better tool (separate unstable writes and commits) for solving this
1233	* problem.
1234	*/
1235	static int wait_for_concurrent_writes(struct file *file)
1236	{
1237	struct inode *inode = file_inode(f: file);
1238	static ino_t last_ino;
1239	static dev_t last_dev;
1240	int err = 0;
1241
1242	if (atomic_read(v: &inode->i_writecount) > 1
1243	|| (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
1244	dprintk("nfsd: write defer %d\n", task_pid_nr(current));
1245	msleep(msecs: 10);
1246	dprintk("nfsd: write resume %d\n", task_pid_nr(current));
1247	}
1248
1249	if (inode_state_read_once(inode) & I_DIRTY) {
1250	dprintk("nfsd: write sync %d\n", task_pid_nr(current));
1251	err = vfs_fsync(file, datasync: 0);
1252	}
1253	last_ino = inode->i_ino;
1254	last_dev = inode->i_sb->s_dev;
1255	return err;
1256	}
1257
1258	struct nfsd_write_dio_seg {
1259	struct iov_iter iter;
1260	int flags;
1261	};
1262
1263	static unsigned long
1264	iov_iter_bvec_offset(const struct iov_iter *iter)
1265	{
1266	return (unsigned long)(iter->bvec->bv_offset + iter->iov_offset);
1267	}
1268
1269	static void
1270	nfsd_write_dio_seg_init(struct nfsd_write_dio_seg *segment,
1271	struct bio_vec *bvec, unsigned int nvecs,
1272	unsigned long total, size_t start, size_t len,
1273	struct kiocb *iocb)
1274	{
1275	iov_iter_bvec(i: &segment->iter, ITER_SOURCE, bvec, nr_segs: nvecs, count: total);
1276	if (start)
1277	iov_iter_advance(i: &segment->iter, bytes: start);
1278	iov_iter_truncate(i: &segment->iter, count: len);
1279	segment->flags = iocb->ki_flags;
1280	}
1281
1282	static unsigned int
1283	nfsd_write_dio_iters_init(struct nfsd_file *nf, struct bio_vec *bvec,
1284	unsigned int nvecs, struct kiocb *iocb,
1285	unsigned long total,
1286	struct nfsd_write_dio_seg segments[3])
1287	{
1288	u32 offset_align = nf->nf_dio_offset_align;
1289	loff_t prefix_end, orig_end, middle_end;
1290	u32 mem_align = nf->nf_dio_mem_align;
1291	size_t prefix, middle, suffix;
1292	loff_t offset = iocb->ki_pos;
1293	unsigned int nsegs = 0;
1294
1295	/*
1296	* Check if direct I/O is feasible for this write request.
1297	* If alignments are not available, the write is too small,
1298	* or no alignment can be found, fall back to buffered I/O.
1299	*/
1300	if (unlikely(!mem_align || !offset_align) ||
1301	unlikely(total < max(offset_align, mem_align)))
1302	goto no_dio;
1303
1304	prefix_end = round_up(offset, offset_align);
1305	orig_end = offset + total;
1306	middle_end = round_down(orig_end, offset_align);
1307
1308	prefix = prefix_end - offset;
1309	middle = middle_end - prefix_end;
1310	suffix = orig_end - middle_end;
1311
1312	if (!middle)
1313	goto no_dio;
1314
1315	if (prefix)
1316	nfsd_write_dio_seg_init(segment: &segments[nsegs++], bvec,
1317	nvecs, total, start: 0, len: prefix, iocb);
1318
1319	nfsd_write_dio_seg_init(segment: &segments[nsegs], bvec, nvecs,
1320	total, start: prefix, len: middle, iocb);
1321
1322	/*
1323	* Check if the bvec iterator is aligned for direct I/O.
1324	*
1325	* bvecs generated from RPC receive buffers are contiguous: After
1326	* the first bvec, all subsequent bvecs start at bv_offset zero
1327	* (page-aligned). Therefore, only the first bvec is checked.
1328	*/
1329	if (iov_iter_bvec_offset(iter: &segments[nsegs].iter) & (mem_align - 1))
1330	goto no_dio;
1331	segments[nsegs].flags |= IOCB_DIRECT;
1332	nsegs++;
1333
1334	if (suffix)
1335	nfsd_write_dio_seg_init(segment: &segments[nsegs++], bvec, nvecs, total,
1336	start: prefix + middle, len: suffix, iocb);
1337
1338	return nsegs;
1339
1340	no_dio:
1341	/* No DIO alignment possible - pack into single non-DIO segment. */
1342	nfsd_write_dio_seg_init(segment: &segments[0], bvec, nvecs, total, start: 0,
1343	len: total, iocb);
1344	return 1;
1345	}
1346
1347	static noinline_for_stack int
1348	nfsd_direct_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
1349	struct nfsd_file *nf, unsigned int nvecs,
1350	unsigned long *cnt, struct kiocb *kiocb)
1351	{
1352	struct nfsd_write_dio_seg segments[3];
1353	struct file *file = nf->nf_file;
1354	unsigned int nsegs, i;
1355	ssize_t host_err;
1356
1357	nsegs = nfsd_write_dio_iters_init(nf, bvec: rqstp->rq_bvec, nvecs,
1358	iocb: kiocb, total: *cnt, segments);
1359
1360	*cnt = 0;
1361	for (i = 0; i < nsegs; i++) {
1362	kiocb->ki_flags = segments[i].flags;
1363	if (kiocb->ki_flags & IOCB_DIRECT)
1364	trace_nfsd_write_direct(rqstp, fhp, offset: kiocb->ki_pos,
1365	len: segments[i].iter.count);
1366	else {
1367	trace_nfsd_write_vector(rqstp, fhp, offset: kiocb->ki_pos,
1368	len: segments[i].iter.count);
1369	/*
1370	* Mark the I/O buffer as evict-able to reduce
1371	* memory contention.
1372	*/
1373	if (nf->nf_file->f_op->fop_flags & FOP_DONTCACHE)
1374	kiocb->ki_flags |= IOCB_DONTCACHE;
1375	}
1376
1377	host_err = vfs_iocb_iter_write(file, iocb: kiocb, iter: &segments[i].iter);
1378	if (host_err < 0)
1379	return host_err;
1380	*cnt += host_err;
1381	if (host_err < segments[i].iter.count)
1382	break; /* partial write */
1383	}
1384
1385	return 0;
1386	}
1387
1388	/**
1389	* nfsd_vfs_write - write data to an already-open file
1390	* @rqstp: RPC execution context
1391	* @fhp: File handle of file to write into
1392	* @nf: An open file matching @fhp
1393	* @offset: Byte offset of start
1394	* @payload: xdr_buf containing the write payload
1395	* @cnt: IN: number of bytes to write, OUT: number of bytes actually written
1396	* @stable: An NFS stable_how value
1397	* @verf: NFS WRITE verifier
1398	*
1399	* Upon return, caller must invoke fh_put on @fhp.
1400	*
1401	* Return values:
1402	* An nfsstat value in network byte order.
1403	*/
1404	__be32
1405	nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
1406	struct nfsd_file *nf, loff_t offset,
1407	const struct xdr_buf *payload, unsigned long *cnt,
1408	int stable, __be32 *verf)
1409	{
1410	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), id: nfsd_net_id);
1411	struct file *file = nf->nf_file;
1412	struct super_block *sb = file_inode(f: file)->i_sb;
1413	struct kiocb kiocb;
1414	struct svc_export *exp;
1415	struct iov_iter iter;
1416	errseq_t since;
1417	__be32 nfserr;
1418	int host_err;
1419	unsigned long exp_op_flags = 0;
1420	unsigned int pflags = current->flags;
1421	bool restore_flags = false;
1422	unsigned int nvecs;
1423
1424	trace_nfsd_write_opened(rqstp, fhp, offset, len: *cnt);
1425
1426	if (sb->s_export_op)
1427	exp_op_flags = sb->s_export_op->flags;
1428
1429	if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
1430	!(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
1431	/*
1432	* We want throttling in balance_dirty_pages()
1433	* and shrink_inactive_list() to only consider
1434	* the backingdev we are writing to, so that nfs to
1435	* localhost doesn't cause nfsd to lock up due to all
1436	* the client's dirty pages or its congested queue.
1437	*/
1438	current->flags |= PF_LOCAL_THROTTLE;
1439	restore_flags = true;
1440	}
1441
1442	exp = fhp->fh_export;
1443
1444	if (!EX_ISSYNC(exp))
1445	stable = NFS_UNSTABLE;
1446	init_sync_kiocb(kiocb: &kiocb, filp: file);
1447	kiocb.ki_pos = offset;
1448	if (likely(!fhp->fh_use_wgather)) {
1449	switch (stable) {
1450	case NFS_FILE_SYNC:
1451	/* persist data and timestamps */
1452	kiocb.ki_flags |= IOCB_DSYNC | IOCB_SYNC;
1453	break;
1454	case NFS_DATA_SYNC:
1455	/* persist data only */
1456	kiocb.ki_flags |= IOCB_DSYNC;
1457	break;
1458	}
1459	}
1460
1461	nvecs = xdr_buf_to_bvec(bvec: rqstp->rq_bvec, bvec_size: rqstp->rq_maxpages, xdr: payload);
1462
1463	since = READ_ONCE(file->f_wb_err);
1464	if (verf)
1465	nfsd_copy_write_verifier(verf, nn);
1466
1467	switch (nfsd_io_cache_write) {
1468	case NFSD_IO_DIRECT:
1469	host_err = nfsd_direct_write(rqstp, fhp, nf, nvecs,
1470	cnt, kiocb: &kiocb);
1471	break;
1472	case NFSD_IO_DONTCACHE:
1473	if (file->f_op->fop_flags & FOP_DONTCACHE)
1474	kiocb.ki_flags |= IOCB_DONTCACHE;
1475	fallthrough;
1476	case NFSD_IO_BUFFERED:
1477	iov_iter_bvec(i: &iter, ITER_SOURCE, bvec: rqstp->rq_bvec, nr_segs: nvecs, count: *cnt);
1478	host_err = vfs_iocb_iter_write(file, iocb: &kiocb, iter: &iter);
1479	if (host_err < 0)
1480	break;
1481	*cnt = host_err;
1482	break;
1483	}
1484	if (host_err < 0) {
1485	commit_reset_write_verifier(nn, rqstp, err: host_err);
1486	goto out_nfserr;
1487	}
1488	nfsd_stats_io_write_add(nn, exp, amount: *cnt);
1489	fsnotify_modify(file);
1490	host_err = filemap_check_wb_err(mapping: file->f_mapping, since);
1491	if (host_err < 0)
1492	goto out_nfserr;
1493
1494	if (stable && fhp->fh_use_wgather) {
1495	host_err = wait_for_concurrent_writes(file);
1496	if (host_err < 0)
1497	commit_reset_write_verifier(nn, rqstp, err: host_err);
1498	}
1499
1500	out_nfserr:
1501	if (host_err >= 0) {
1502	trace_nfsd_write_io_done(rqstp, fhp, offset, len: *cnt);
1503	nfserr = nfs_ok;
1504	} else {
1505	trace_nfsd_write_err(rqstp, fhp, offset, len: host_err);
1506	nfserr = nfserrno(errno: host_err);
1507	}
1508	if (restore_flags)
1509	current_restore_flags(orig_flags: pflags, PF_LOCAL_THROTTLE);
1510	return nfserr;
1511	}
1512
1513	/**
1514	* nfsd_read_splice_ok - check if spliced reading is supported
1515	* @rqstp: RPC transaction context
1516	*
1517	* Return values:
1518	* %true: nfsd_splice_read() may be used
1519	* %false: nfsd_splice_read() must not be used
1520	*
1521	* NFS READ normally uses splice to send data in-place. However the
1522	* data in cache can change after the reply's MIC is computed but
1523	* before the RPC reply is sent. To prevent the client from
1524	* rejecting the server-computed MIC in this somewhat rare case, do
1525	* not use splice with the GSS integrity and privacy services.
1526	*/
1527	bool nfsd_read_splice_ok(struct svc_rqst *rqstp)
1528	{
1529	if (nfsd_disable_splice_read)
1530	return false;
1531	switch (svc_auth_flavor(rqstp)) {
1532	case RPC_AUTH_GSS_KRB5I:
1533	case RPC_AUTH_GSS_KRB5P:
1534	return false;
1535	}
1536	return true;
1537	}
1538
1539	/**
1540	* nfsd_read - Read data from a file
1541	* @rqstp: RPC transaction context
1542	* @fhp: file handle of file to be read
1543	* @offset: starting byte offset
1544	* @count: IN: requested number of bytes; OUT: number of bytes read
1545	* @eof: OUT: set non-zero if operation reached the end of the file
1546	*
1547	* The caller must verify that there is enough space in @rqstp.rq_res
1548	* to perform this operation.
1549	*
1550	* N.B. After this call fhp needs an fh_put
1551	*
1552	* Returns nfs_ok on success, otherwise an nfserr stat value is
1553	* returned.
1554	*/
1555	__be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1556	loff_t offset, unsigned long *count, u32 *eof)
1557	{
1558	struct nfsd_file *nf;
1559	struct file *file;
1560	__be32 err;
1561
1562	trace_nfsd_read_start(rqstp, fhp, offset, len: *count);
1563	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_READ, nfp: &nf);
1564	if (err)
1565	return err;
1566
1567	file = nf->nf_file;
1568	if (file->f_op->splice_read && nfsd_read_splice_ok(rqstp))
1569	err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
1570	else
1571	err = nfsd_iter_read(rqstp, fhp, nf, offset, count, base: 0, eof);
1572
1573	nfsd_file_put(nf);
1574	trace_nfsd_read_done(rqstp, fhp, offset, len: *count);
1575	return err;
1576	}
1577
1578	/**
1579	* nfsd_write - open a file and write data to it
1580	* @rqstp: RPC execution context
1581	* @fhp: File handle of file to write into; nfsd_write() may modify it
1582	* @offset: Byte offset of start
1583	* @payload: xdr_buf containing the write payload
1584	* @cnt: IN: number of bytes to write, OUT: number of bytes actually written
1585	* @stable: An NFS stable_how value
1586	* @verf: NFS WRITE verifier
1587	*
1588	* Upon return, caller must invoke fh_put on @fhp.
1589	*
1590	* Return values:
1591	* An nfsstat value in network byte order.
1592	*/
1593	__be32
1594	nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1595	const struct xdr_buf *payload, unsigned long *cnt, int stable,
1596	__be32 *verf)
1597	{
1598	struct nfsd_file *nf;
1599	__be32 err;
1600
1601	trace_nfsd_write_start(rqstp, fhp, offset, len: *cnt);
1602
1603	err = nfsd_file_acquire_gc(rqstp, fhp, NFSD_MAY_WRITE, nfp: &nf);
1604	if (err)
1605	goto out;
1606
1607	err = nfsd_vfs_write(rqstp, fhp, nf, offset, payload, cnt,
1608	stable, verf);
1609	nfsd_file_put(nf);
1610	out:
1611	trace_nfsd_write_done(rqstp, fhp, offset, len: *cnt);
1612	return err;
1613	}
1614
1615	/**
1616	* nfsd_commit - Commit pending writes to stable storage
1617	* @rqstp: RPC request being processed
1618	* @fhp: NFS filehandle
1619	* @nf: target file
1620	* @offset: raw offset from beginning of file
1621	* @count: raw count of bytes to sync
1622	* @verf: filled in with the server's current write verifier
1623	*
1624	* Note: we guarantee that data that lies within the range specified
1625	* by the 'offset' and 'count' parameters will be synced. The server
1626	* is permitted to sync data that lies outside this range at the
1627	* same time.
1628	*
1629	* Unfortunately we cannot lock the file to make sure we return full WCC
1630	* data to the client, as locking happens lower down in the filesystem.
1631	*
1632	* Return values:
1633	* An nfsstat value in network byte order.
1634	*/
1635	__be32
1636	nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
1637	u64 offset, u32 count, __be32 *verf)
1638	{
1639	__be32 err = nfs_ok;
1640	u64 maxbytes;
1641	loff_t start, end;
1642	struct nfsd_net *nn;
1643
1644	trace_nfsd_commit_start(rqstp, fhp, offset, len: count);
1645
1646	/*
1647	* Convert the client-provided (offset, count) range to a
1648	* (start, end) range. If the client-provided range falls
1649	* outside the maximum file size of the underlying FS,
1650	* clamp the sync range appropriately.
1651	*/
1652	start = 0;
1653	end = LLONG_MAX;
1654	maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
1655	if (offset < maxbytes) {
1656	start = offset;
1657	if (count && (offset + count - 1 < maxbytes))
1658	end = offset + count - 1;
1659	}
1660
1661	nn = net_generic(net: nf->nf_net, id: nfsd_net_id);
1662	if (EX_ISSYNC(fhp->fh_export)) {
1663	errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
1664	int err2;
1665
1666	err2 = vfs_fsync_range(file: nf->nf_file, start, end, datasync: 0);
1667	switch (err2) {
1668	case 0:
1669	nfsd_copy_write_verifier(verf, nn);
1670	err2 = filemap_check_wb_err(mapping: nf->nf_file->f_mapping,
1671	since);
1672	err = nfserrno(errno: err2);
1673	break;
1674	case -EINVAL:
1675	err = nfserr_notsupp;
1676	break;
1677	default:
1678	commit_reset_write_verifier(nn, rqstp, err: err2);
1679	err = nfserrno(errno: err2);
1680	}
1681	} else
1682	nfsd_copy_write_verifier(verf, nn);
1683
1684	trace_nfsd_commit_done(rqstp, fhp, offset, len: count);
1685	return err;
1686	}
1687
1688	/**
1689	* nfsd_create_setattr - Set a created file's attributes
1690	* @rqstp: RPC transaction being executed
1691	* @fhp: NFS filehandle of parent directory
1692	* @resfhp: NFS filehandle of new object
1693	* @attrs: requested attributes of new object
1694	*
1695	* Returns nfs_ok on success, or an nfsstat in network byte order.
1696	*/
1697	__be32
1698	nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
1699	struct svc_fh *resfhp, struct nfsd_attrs *attrs)
1700	{
1701	struct iattr *iap = attrs->na_iattr;
1702	__be32 status;
1703
1704	/*
1705	* Mode has already been set by file creation.
1706	*/
1707	iap->ia_valid &= ~ATTR_MODE;
1708
1709	/*
1710	* Setting uid/gid works only for root. Irix appears to
1711	* send along the gid on create when it tries to implement
1712	* setgid directories via NFS:
1713	*/
1714	if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1715	iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1716
1717	/*
1718	* Callers expect new file metadata to be committed even
1719	* if the attributes have not changed.
1720	*/
1721	if (nfsd_attrs_valid(attrs))
1722	status = nfsd_setattr(rqstp, resfhp, attrs, NULL);
1723	else
1724	status = nfserrno(commit_metadata(resfhp));
1725
1726	/*
1727	* Transactional filesystems had a chance to commit changes
1728	* for both parent and child simultaneously making the
1729	* following commit_metadata a noop in many cases.
1730	*/
1731	if (!status)
1732	status = nfserrno(commit_metadata(fhp));
1733
1734	/*
1735	* Update the new filehandle to pick up the new attributes.
1736	*/
1737	if (!status)
1738	status = fh_update(resfhp);
1739
1740	return status;
1741	}
1742
1743	/* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1744	* setting size to 0 may fail for some specific file systems by the permission
1745	* checking which requires WRITE permission but the mode is 000.
1746	* we ignore the resizing(to 0) on the just new created file, since the size is
1747	* 0 after file created.
1748	*
1749	* call this only after vfs_create() is called.
1750	* */
1751	static void
1752	nfsd_check_ignore_resizing(struct iattr *iap)
1753	{
1754	if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1755	iap->ia_valid &= ~ATTR_SIZE;
1756	}
1757
1758	/* The parent directory should already be locked - we will unlock */
1759	__be32
1760	nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1761	struct nfsd_attrs *attrs,
1762	int type, dev_t rdev, struct svc_fh *resfhp)
1763	{
1764	struct dentry *dentry, *dchild;
1765	struct inode *dirp;
1766	struct iattr *iap = attrs->na_iattr;
1767	__be32 err;
1768	int host_err = 0;
1769
1770	dentry = fhp->fh_dentry;
1771	dirp = d_inode(dentry);
1772
1773	dchild = dget(dentry: resfhp->fh_dentry);
1774	err = nfsd_permission(cred: &rqstp->rq_cred, exp: fhp->fh_export, dentry,
1775	NFSD_MAY_CREATE);
1776	if (err)
1777	goto out;
1778
1779	if (!(iap->ia_valid & ATTR_MODE))
1780	iap->ia_mode = 0;
1781	iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1782
1783	if (!IS_POSIXACL(dirp))
1784	iap->ia_mode &= ~current_umask();
1785
1786	err = 0;
1787	switch (type) {
1788	case S_IFREG:
1789	host_err = vfs_create(&nop_mnt_idmap, dchild, iap->ia_mode, NULL);
1790	if (!host_err)
1791	nfsd_check_ignore_resizing(iap);
1792	break;
1793	case S_IFDIR:
1794	dchild = vfs_mkdir(&nop_mnt_idmap, dirp, dchild, iap->ia_mode, NULL);
1795	if (IS_ERR(ptr: dchild)) {
1796	host_err = PTR_ERR(ptr: dchild);
1797	} else if (d_is_negative(dentry: dchild)) {
1798	err = nfserr_serverfault;
1799	goto out;
1800	} else if (unlikely(dchild != resfhp->fh_dentry)) {
1801	dput(resfhp->fh_dentry);
1802	resfhp->fh_dentry = dget(dentry: dchild);
1803	}
1804	break;
1805	case S_IFCHR:
1806	case S_IFBLK:
1807	case S_IFIFO:
1808	case S_IFSOCK:
1809	host_err = vfs_mknod(&nop_mnt_idmap, dirp, dchild,
1810	iap->ia_mode, rdev, NULL);
1811	break;
1812	default:
1813	printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1814	type);
1815	host_err = -EINVAL;
1816	}
1817	if (host_err < 0)
1818	goto out_nfserr;
1819
1820	err = nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1821
1822	out:
1823	if (!err)
1824	fh_fill_post_attrs(fhp);
1825	end_creating(child: dchild);
1826	return err;
1827
1828	out_nfserr:
1829	err = nfserrno(errno: host_err);
1830	goto out;
1831	}
1832
1833	/*
1834	* Create a filesystem object (regular, directory, special).
1835	* Note that the parent directory is left locked.
1836	*
1837	* N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1838	*/
1839	__be32
1840	nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1841	char *fname, int flen, struct nfsd_attrs *attrs,
1842	int type, dev_t rdev, struct svc_fh *resfhp)
1843	{
1844	struct dentry *dentry, *dchild = NULL;
1845	__be32 err;
1846	int host_err;
1847
1848	trace_nfsd_vfs_create(rqstp, fhp, type, name: fname, len: flen);
1849
1850	if (isdotent(fname, flen))
1851	return nfserr_exist;
1852
1853	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1854	if (err)
1855	return err;
1856
1857	dentry = fhp->fh_dentry;
1858
1859	host_err = fh_want_write(fhp);
1860	if (host_err)
1861	return nfserrno(errno: host_err);
1862
1863	dchild = start_creating(idmap: &nop_mnt_idmap, parent: dentry, name: &QSTR_LEN(fname, flen));
1864	host_err = PTR_ERR(ptr: dchild);
1865	if (IS_ERR(ptr: dchild))
1866	return nfserrno(errno: host_err);
1867
1868	err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1869	if (err)
1870	goto out_unlock;
1871	err = fh_fill_pre_attrs(fhp);
1872	if (err != nfs_ok)
1873	goto out_unlock;
1874	err = nfsd_create_locked(rqstp, fhp, attrs, type, rdev, resfhp);
1875	/* nfsd_create_locked() unlocked the parent */
1876	dput(dchild);
1877	return err;
1878
1879	out_unlock:
1880	end_creating(child: dchild);
1881	return err;
1882	}
1883
1884	/*
1885	* Read a symlink. On entry, *lenp must contain the maximum path length that
1886	* fits into the buffer. On return, it contains the true length.
1887	* N.B. After this call fhp needs an fh_put
1888	*/
1889	__be32
1890	nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1891	{
1892	__be32 err;
1893	const char *link;
1894	struct path path;
1895	DEFINE_DELAYED_CALL(done);
1896	int len;
1897
1898	err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1899	if (unlikely(err))
1900	return err;
1901
1902	path.mnt = fhp->fh_export->ex_path.mnt;
1903	path.dentry = fhp->fh_dentry;
1904
1905	if (unlikely(!d_is_symlink(path.dentry)))
1906	return nfserr_inval;
1907
1908	touch_atime(&path);
1909
1910	link = vfs_get_link(path.dentry, &done);
1911	if (IS_ERR(ptr: link))
1912	return nfserrno(errno: PTR_ERR(ptr: link));
1913
1914	len = strlen(link);
1915	if (len < *lenp)
1916	*lenp = len;
1917	memcpy(buf, link, *lenp);
1918	do_delayed_call(call: &done);
1919	return 0;
1920	}
1921
1922	/**
1923	* nfsd_symlink - Create a symlink and look up its inode
1924	* @rqstp: RPC transaction being executed
1925	* @fhp: NFS filehandle of parent directory
1926	* @fname: filename of the new symlink
1927	* @flen: length of @fname
1928	* @path: content of the new symlink (NUL-terminated)
1929	* @attrs: requested attributes of new object
1930	* @resfhp: NFS filehandle of new object
1931	*
1932	* N.B. After this call _both_ fhp and resfhp need an fh_put
1933	*
1934	* Returns nfs_ok on success, or an nfsstat in network byte order.
1935	*/
1936	__be32
1937	nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1938	char *fname, int flen,
1939	char *path, struct nfsd_attrs *attrs,
1940	struct svc_fh *resfhp)
1941	{
1942	struct dentry *dentry, *dnew;
1943	__be32 err, cerr;
1944	int host_err;
1945
1946	trace_nfsd_vfs_symlink(rqstp, fhp, name: fname, namelen: flen, target: path);
1947
1948	err = nfserr_noent;
1949	if (!flen || path[0] == '\0')
1950	goto out;
1951	err = nfserr_exist;
1952	if (isdotent(fname, flen))
1953	goto out;
1954
1955	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1956	if (err)
1957	goto out;
1958
1959	host_err = fh_want_write(fhp);
1960	if (host_err) {
1961	err = nfserrno(errno: host_err);
1962	goto out;
1963	}
1964
1965	dentry = fhp->fh_dentry;
1966	dnew = start_creating(idmap: &nop_mnt_idmap, parent: dentry, name: &QSTR_LEN(fname, flen));
1967	if (IS_ERR(ptr: dnew)) {
1968	err = nfserrno(errno: PTR_ERR(ptr: dnew));
1969	goto out_drop_write;
1970	}
1971	err = fh_fill_pre_attrs(fhp);
1972	if (err != nfs_ok)
1973	goto out_unlock;
1974	host_err = vfs_symlink(&nop_mnt_idmap, d_inode(dentry), dnew, path, NULL);
1975	err = nfserrno(errno: host_err);
1976	cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1977	if (!err)
1978	nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
1979	fh_fill_post_attrs(fhp);
1980	out_unlock:
1981	end_creating(child: dnew);
1982	if (!err)
1983	err = nfserrno(errno: commit_metadata(fhp));
1984	if (!err)
1985	err = cerr;
1986	out_drop_write:
1987	fh_drop_write(fhp);
1988	out:
1989	return err;
1990	}
1991
1992	/**
1993	* nfsd_link - create a link
1994	* @rqstp: RPC transaction context
1995	* @ffhp: the file handle of the directory where the new link is to be created
1996	* @name: the filename of the new link
1997	* @len: the length of @name in octets
1998	* @tfhp: the file handle of an existing file object
1999	*
2000	* After this call _both_ ffhp and tfhp need an fh_put.
2001	*
2002	* Returns a generic NFS status code in network byte-order.
2003	*/
2004	__be32
2005	nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
2006	char *name, int len, struct svc_fh *tfhp)
2007	{
2008	struct dentry *ddir, *dnew, *dold;
2009	struct inode *dirp;
2010	int type;
2011	__be32 err;
2012	int host_err;
2013
2014	trace_nfsd_vfs_link(rqstp, sfhp: ffhp, tfhp, name, namelen: len);
2015
2016	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
2017	if (err)
2018	goto out;
2019	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
2020	if (err)
2021	goto out;
2022	err = nfserr_isdir;
2023	if (d_is_dir(dentry: tfhp->fh_dentry))
2024	goto out;
2025	err = nfserr_perm;
2026	if (!len)
2027	goto out;
2028	err = nfserr_exist;
2029	if (isdotent(name, len))
2030	goto out;
2031
2032	err = nfs_ok;
2033	type = d_inode(dentry: tfhp->fh_dentry)->i_mode & S_IFMT;
2034	host_err = fh_want_write(fhp: tfhp);
2035	if (host_err)
2036	goto out;
2037
2038	ddir = ffhp->fh_dentry;
2039	dirp = d_inode(dentry: ddir);
2040	dnew = start_creating(idmap: &nop_mnt_idmap, parent: ddir, name: &QSTR_LEN(name, len));
2041
2042	if (IS_ERR(ptr: dnew)) {
2043	host_err = PTR_ERR(ptr: dnew);
2044	goto out_drop_write;
2045	}
2046
2047	dold = tfhp->fh_dentry;
2048
2049	err = nfserr_noent;
2050	if (d_really_is_negative(dentry: dold))
2051	goto out_unlock;
2052	err = fh_fill_pre_attrs(fhp: ffhp);
2053	if (err != nfs_ok)
2054	goto out_unlock;
2055	host_err = vfs_link(dold, &nop_mnt_idmap, dirp, dnew, NULL);
2056	fh_fill_post_attrs(fhp: ffhp);
2057	out_unlock:
2058	end_creating(child: dnew);
2059	if (!host_err) {
2060	host_err = commit_metadata(fhp: ffhp);
2061	if (!host_err)
2062	host_err = commit_metadata(fhp: tfhp);
2063	}
2064
2065	out_drop_write:
2066	fh_drop_write(fhp: tfhp);
2067	if (host_err == -EBUSY) {
2068	/*
2069	* See RFC 8881 Section 18.9.4 para 1-2: NFSv4 LINK
2070	* wants a status unique to the object type.
2071	*/
2072	if (type != S_IFDIR)
2073	err = nfserr_file_open;
2074	else
2075	err = nfserr_acces;
2076	}
2077	out:
2078	return err != nfs_ok ? err : nfserrno(errno: host_err);
2079	}
2080
2081	static void
2082	nfsd_close_cached_files(struct dentry *dentry)
2083	{
2084	struct inode *inode = d_inode(dentry);
2085
2086	if (inode && S_ISREG(inode->i_mode))
2087	nfsd_file_close_inode_sync(inode);
2088	}
2089
2090	static bool
2091	nfsd_has_cached_files(struct dentry *dentry)
2092	{
2093	bool ret = false;
2094	struct inode *inode = d_inode(dentry);
2095
2096	if (inode && S_ISREG(inode->i_mode))
2097	ret = nfsd_file_is_cached(inode);
2098	return ret;
2099	}
2100
2101	/**
2102	* nfsd_rename - rename a directory entry
2103	* @rqstp: RPC transaction context
2104	* @ffhp: the file handle of parent directory containing the entry to be renamed
2105	* @fname: the filename of directory entry to be renamed
2106	* @flen: the length of @fname in octets
2107	* @tfhp: the file handle of parent directory to contain the renamed entry
2108	* @tname: the filename of the new entry
2109	* @tlen: the length of @tlen in octets
2110	*
2111	* After this call _both_ ffhp and tfhp need an fh_put.
2112	*
2113	* Returns a generic NFS status code in network byte-order.
2114	*/
2115	__be32
2116	nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
2117	struct svc_fh *tfhp, char *tname, int tlen)
2118	{
2119	struct dentry *fdentry, *tdentry;
2120	int type = S_IFDIR;
2121	struct renamedata rd = {};
2122	__be32 err;
2123	int host_err;
2124	struct dentry *close_cached;
2125
2126	trace_nfsd_vfs_rename(rqstp, sfhp: ffhp, tfhp, source: fname, sourcelen: flen, target: tname, targetlen: tlen);
2127
2128	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
2129	if (err)
2130	goto out;
2131	err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
2132	if (err)
2133	goto out;
2134
2135	fdentry = ffhp->fh_dentry;
2136
2137	tdentry = tfhp->fh_dentry;
2138
2139	err = nfserr_perm;
2140	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
2141	goto out;
2142
2143	err = nfserr_xdev;
2144	if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
2145	goto out;
2146	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
2147	goto out;
2148
2149	retry:
2150	close_cached = NULL;
2151	host_err = fh_want_write(fhp: ffhp);
2152	if (host_err) {
2153	err = nfserrno(errno: host_err);
2154	goto out;
2155	}
2156
2157	rd.mnt_idmap = &nop_mnt_idmap;
2158	rd.old_parent = fdentry;
2159	rd.new_parent = tdentry;
2160
2161	host_err = start_renaming(rd: &rd, lookup_flags: 0, old_last: &QSTR_LEN(fname, flen),
2162	new_last: &QSTR_LEN(tname, tlen));
2163
2164	if (host_err) {
2165	err = nfserrno(errno: host_err);
2166	goto out_want_write;
2167	}
2168	err = fh_fill_pre_attrs(fhp: ffhp);
2169	if (err != nfs_ok)
2170	goto out_unlock;
2171	err = fh_fill_pre_attrs(fhp: tfhp);
2172	if (err != nfs_ok)
2173	goto out_unlock;
2174
2175	type = d_inode(dentry: rd.old_dentry)->i_mode & S_IFMT;
2176
2177	if (d_inode(dentry: rd.new_dentry))
2178	type = d_inode(dentry: rd.new_dentry)->i_mode & S_IFMT;
2179
2180	if ((rd.new_dentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
2181	nfsd_has_cached_files(dentry: rd.new_dentry)) {
2182	close_cached = dget(dentry: rd.new_dentry);
2183	goto out_unlock;
2184	} else {
2185	int retries;
2186
2187	for (retries = 1;;) {
2188	host_err = vfs_rename(&rd);
2189	if (host_err != -EAGAIN || !retries--)
2190	break;
2191	if (!nfsd_wait_for_delegreturn(rqstp, inode: d_inode(dentry: rd.old_dentry)))
2192	break;
2193	}
2194	if (!host_err) {
2195	host_err = commit_metadata(fhp: tfhp);
2196	if (!host_err)
2197	host_err = commit_metadata(fhp: ffhp);
2198	}
2199	}
2200	if (host_err == -EBUSY) {
2201	/*
2202	* See RFC 8881 Section 18.26.4 para 1-3: NFSv4 RENAME
2203	* wants a status unique to the object type.
2204	*/
2205	if (type != S_IFDIR)
2206	err = nfserr_file_open;
2207	else
2208	err = nfserr_acces;
2209	} else {
2210	err = nfserrno(errno: host_err);
2211	}
2212
2213	if (!close_cached) {
2214	fh_fill_post_attrs(fhp: ffhp);
2215	fh_fill_post_attrs(fhp: tfhp);
2216	}
2217	out_unlock:
2218	end_renaming(rd: &rd);
2219	out_want_write:
2220	fh_drop_write(fhp: ffhp);
2221
2222	/*
2223	* If the target dentry has cached open files, then we need to
2224	* try to close them prior to doing the rename. Final fput
2225	* shouldn't be done with locks held however, so we delay it
2226	* until this point and then reattempt the whole shebang.
2227	*/
2228	if (close_cached) {
2229	nfsd_close_cached_files(dentry: close_cached);
2230	dput(close_cached);
2231	goto retry;
2232	}
2233	out:
2234	return err;
2235	}
2236
2237	/**
2238	* nfsd_unlink - remove a directory entry
2239	* @rqstp: RPC transaction context
2240	* @fhp: the file handle of the parent directory to be modified
2241	* @type: enforced file type of the object to be removed
2242	* @fname: the name of directory entry to be removed
2243	* @flen: length of @fname in octets
2244	*
2245	* After this call fhp needs an fh_put.
2246	*
2247	* Returns a generic NFS status code in network byte-order.
2248	*/
2249	__be32
2250	nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
2251	char *fname, int flen)
2252	{
2253	struct dentry *dentry, *rdentry;
2254	struct inode *dirp;
2255	struct inode *rinode = NULL;
2256	__be32 err;
2257	int host_err;
2258
2259	trace_nfsd_vfs_unlink(rqstp, fhp, name: fname, len: flen);
2260
2261	err = nfserr_acces;
2262	if (!flen || isdotent(fname, flen))
2263	goto out;
2264	err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
2265	if (err)
2266	goto out;
2267
2268	host_err = fh_want_write(fhp);
2269	if (host_err)
2270	goto out_nfserr;
2271
2272	dentry = fhp->fh_dentry;
2273	dirp = d_inode(dentry);
2274
2275	rdentry = start_removing(idmap: &nop_mnt_idmap, parent: dentry, name: &QSTR_LEN(fname, flen));
2276
2277	host_err = PTR_ERR(ptr: rdentry);
2278	if (IS_ERR(ptr: rdentry))
2279	goto out_drop_write;
2280
2281	err = fh_fill_pre_attrs(fhp);
2282	if (err != nfs_ok)
2283	goto out_unlock;
2284
2285	rinode = d_inode(dentry: rdentry);
2286	/* Prevent truncation until after locks dropped */
2287	ihold(inode: rinode);
2288
2289	if (!type)
2290	type = d_inode(dentry: rdentry)->i_mode & S_IFMT;
2291
2292	if (type != S_IFDIR) {
2293	int retries;
2294
2295	if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
2296	nfsd_close_cached_files(dentry: rdentry);
2297
2298	for (retries = 1;;) {
2299	host_err = vfs_unlink(&nop_mnt_idmap, dirp, rdentry, NULL);
2300	if (host_err != -EAGAIN || !retries--)
2301	break;
2302	if (!nfsd_wait_for_delegreturn(rqstp, inode: rinode))
2303	break;
2304	}
2305	} else {
2306	host_err = vfs_rmdir(&nop_mnt_idmap, dirp, rdentry, NULL);
2307	}
2308	fh_fill_post_attrs(fhp);
2309
2310	out_unlock:
2311	end_removing(child: rdentry);
2312	if (!err && !host_err)
2313	host_err = commit_metadata(fhp);
2314	iput(rinode); /* truncate the inode here */
2315
2316	out_drop_write:
2317	fh_drop_write(fhp);
2318	out_nfserr:
2319	if (host_err == -EBUSY) {
2320	/*
2321	* See RFC 8881 Section 18.25.4 para 4: NFSv4 REMOVE
2322	* wants a status unique to the object type.
2323	*/
2324	if (type != S_IFDIR)
2325	err = nfserr_file_open;
2326	else
2327	err = nfserr_acces;
2328	}
2329	out:
2330	return err != nfs_ok ? err : nfserrno(errno: host_err);
2331	}
2332
2333	/*
2334	* We do this buffering because we must not call back into the file
2335	* system's ->lookup() method from the filldir callback. That may well
2336	* deadlock a number of file systems.
2337	*
2338	* This is based heavily on the implementation of same in XFS.
2339	*/
2340	struct buffered_dirent {
2341	u64 ino;
2342	loff_t offset;
2343	int namlen;
2344	unsigned int d_type;
2345	char name[];
2346	};
2347
2348	struct readdir_data {
2349	struct dir_context ctx;
2350	char *dirent;
2351	size_t used;
2352	int full;
2353	};
2354
2355	static bool nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
2356	int namlen, loff_t offset, u64 ino,
2357	unsigned int d_type)
2358	{
2359	struct readdir_data *buf =
2360	container_of(ctx, struct readdir_data, ctx);
2361	struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
2362	unsigned int reclen;
2363
2364	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
2365	if (buf->used + reclen > PAGE_SIZE) {
2366	buf->full = 1;
2367	return false;
2368	}
2369
2370	de->namlen = namlen;
2371	de->offset = offset;
2372	de->ino = ino;
2373	de->d_type = d_type;
2374	memcpy(de->name, name, namlen);
2375	buf->used += reclen;
2376
2377	return true;
2378	}
2379
2380	static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
2381	nfsd_filldir_t func, struct readdir_cd *cdp,
2382	loff_t *offsetp)
2383	{
2384	struct buffered_dirent *de;
2385	int host_err;
2386	int size;
2387	loff_t offset;
2388	struct readdir_data buf = {
2389	.ctx.actor = nfsd_buffered_filldir,
2390	.dirent = (void *)__get_free_page(GFP_KERNEL)
2391	};
2392
2393	if (!buf.dirent)
2394	return nfserrno(errno: -ENOMEM);
2395
2396	offset = *offsetp;
2397
2398	while (1) {
2399	unsigned int reclen;
2400
2401	cdp->err = nfserr_eof; /* will be cleared on successful read */
2402	buf.used = 0;
2403	buf.full = 0;
2404
2405	host_err = iterate_dir(file, &buf.ctx);
2406	if (buf.full)
2407	host_err = 0;
2408
2409	if (host_err < 0)
2410	break;
2411
2412	size = buf.used;
2413
2414	if (!size)
2415	break;
2416
2417	de = (struct buffered_dirent *)buf.dirent;
2418	while (size > 0) {
2419	offset = de->offset;
2420
2421	if (func(cdp, de->name, de->namlen, de->offset,
2422	de->ino, de->d_type))
2423	break;
2424
2425	if (cdp->err != nfs_ok)
2426	break;
2427
2428	trace_nfsd_dirent(fhp, ino: de->ino, name: de->name, namlen: de->namlen);
2429
2430	reclen = ALIGN(sizeof(*de) + de->namlen,
2431	sizeof(u64));
2432	size -= reclen;
2433	de = (struct buffered_dirent *)((char *)de + reclen);
2434	}
2435	if (size > 0) /* We bailed out early */
2436	break;
2437
2438	offset = vfs_llseek(file, offset: 0, SEEK_CUR);
2439	}
2440
2441	free_page((unsigned long)(buf.dirent));
2442
2443	if (host_err)
2444	return nfserrno(errno: host_err);
2445
2446	*offsetp = offset;
2447	return cdp->err;
2448	}
2449
2450	/**
2451	* nfsd_readdir - Read entries from a directory
2452	* @rqstp: RPC transaction context
2453	* @fhp: NFS file handle of directory to be read
2454	* @offsetp: OUT: seek offset of final entry that was read
2455	* @cdp: OUT: an eof error value
2456	* @func: entry filler actor
2457	*
2458	* This implementation ignores the NFSv3/4 verifier cookie.
2459	*
2460	* NB: normal system calls hold file->f_pos_lock when calling
2461	* ->iterate_shared and ->llseek, but nfsd_readdir() does not.
2462	* Because the struct file acquired here is not visible to other
2463	* threads, it's internal state does not need mutex protection.
2464	*
2465	* Returns nfs_ok on success, otherwise an nfsstat code is
2466	* returned.
2467	*/
2468	__be32
2469	nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp,
2470	struct readdir_cd *cdp, nfsd_filldir_t func)
2471	{
2472	__be32 err;
2473	struct file *file;
2474	loff_t offset = *offsetp;
2475	int may_flags = NFSD_MAY_READ;
2476
2477	err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, filp: &file);
2478	if (err)
2479	goto out;
2480
2481	if (fhp->fh_64bit_cookies)
2482	file->f_mode |= FMODE_64BITHASH;
2483	else
2484	file->f_mode |= FMODE_32BITHASH;
2485
2486	offset = vfs_llseek(file, offset, SEEK_SET);
2487	if (offset < 0) {
2488	err = nfserrno(errno: (int)offset);
2489	goto out_close;
2490	}
2491
2492	err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
2493
2494	if (err == nfserr_eof || err == nfserr_toosmall)
2495	err = nfs_ok; /* can still be found in ->err */
2496	out_close:
2497	nfsd_filp_close(fp: file);
2498	out:
2499	return err;
2500	}
2501
2502	/**
2503	* nfsd_filp_close: close a file synchronously
2504	* @fp: the file to close
2505	*
2506	* nfsd_filp_close() is similar in behaviour to filp_close().
2507	* The difference is that if this is the final close on the
2508	* file, the that finalisation happens immediately, rather then
2509	* being handed over to a work_queue, as it the case for
2510	* filp_close().
2511	* When a user-space process closes a file (even when using
2512	* filp_close() the finalisation happens before returning to
2513	* userspace, so it is effectively synchronous. When a kernel thread
2514	* uses file_close(), on the other hand, the handling is completely
2515	* asynchronous. This means that any cost imposed by that finalisation
2516	* is not imposed on the nfsd thread, and nfsd could potentually
2517	* close files more quickly than the work queue finalises the close,
2518	* which would lead to unbounded growth in the queue.
2519	*
2520	* In some contexts is it not safe to synchronously wait for
2521	* close finalisation (see comment for __fput_sync()), but nfsd
2522	* does not match those contexts. In partcilarly it does not, at the
2523	* time that this function is called, hold and locks and no finalisation
2524	* of any file, socket, or device driver would have any cause to wait
2525	* for nfsd to make progress.
2526	*/
2527	void nfsd_filp_close(struct file *fp)
2528	{
2529	get_file(f: fp);
2530	filp_close(fp, NULL);
2531	__fput_sync(fp);
2532	}
2533
2534	/*
2535	* Get file system stats
2536	* N.B. After this call fhp needs an fh_put
2537	*/
2538	__be32
2539	nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
2540	{
2541	__be32 err;
2542
2543	trace_nfsd_vfs_statfs(rqstp, fhp);
2544
2545	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
2546	if (!err) {
2547	struct path path = {
2548	.mnt = fhp->fh_export->ex_path.mnt,
2549	.dentry = fhp->fh_dentry,
2550	};
2551	if (vfs_statfs(&path, stat))
2552	err = nfserr_io;
2553	}
2554	return err;
2555	}
2556
2557	static int exp_rdonly(struct svc_cred *cred, struct svc_export *exp)
2558	{
2559	return nfsexp_flags(cred, exp) & NFSEXP_READONLY;
2560	}
2561
2562	#ifdef CONFIG_NFSD_V4
2563	/*
2564	* Helper function to translate error numbers. In the case of xattr operations,
2565	* some error codes need to be translated outside of the standard translations.
2566	*
2567	* ENODATA needs to be translated to nfserr_noxattr.
2568	* E2BIG to nfserr_xattr2big.
2569	*
2570	* Additionally, vfs_listxattr can return -ERANGE. This means that the
2571	* file has too many extended attributes to retrieve inside an
2572	* XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
2573	* filesystems will allow the adding of extended attributes until they hit
2574	* their own internal limit. This limit may be larger than XATTR_LIST_MAX.
2575	* So, at that point, the attributes are present and valid, but can't
2576	* be retrieved using listxattr, since the upper level xattr code enforces
2577	* the XATTR_LIST_MAX limit.
2578	*
2579	* This bug means that we need to deal with listxattr returning -ERANGE. The
2580	* best mapping is to return TOOSMALL.
2581	*/
2582	static __be32
2583	nfsd_xattr_errno(int err)
2584	{
2585	switch (err) {
2586	case -ENODATA:
2587	return nfserr_noxattr;
2588	case -E2BIG:
2589	return nfserr_xattr2big;
2590	case -ERANGE:
2591	return nfserr_toosmall;
2592	}
2593	return nfserrno(errno: err);
2594	}
2595
2596	/*
2597	* Retrieve the specified user extended attribute. To avoid always
2598	* having to allocate the maximum size (since we are not getting
2599	* a maximum size from the RPC), do a probe + alloc. Hold a reader
2600	* lock on i_rwsem to prevent the extended attribute from changing
2601	* size while we're doing this.
2602	*/
2603	__be32
2604	nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2605	void **bufp, int *lenp)
2606	{
2607	ssize_t len;
2608	__be32 err;
2609	char *buf;
2610	struct inode *inode;
2611	struct dentry *dentry;
2612
2613	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2614	if (err)
2615	return err;
2616
2617	err = nfs_ok;
2618	dentry = fhp->fh_dentry;
2619	inode = d_inode(dentry);
2620
2621	inode_lock_shared(inode);
2622
2623	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, NULL, 0);
2624
2625	/*
2626	* Zero-length attribute, just return.
2627	*/
2628	if (len == 0) {
2629	*bufp = NULL;
2630	*lenp = 0;
2631	goto out;
2632	}
2633
2634	if (len < 0) {
2635	err = nfsd_xattr_errno(err: len);
2636	goto out;
2637	}
2638
2639	if (len > *lenp) {
2640	err = nfserr_toosmall;
2641	goto out;
2642	}
2643
2644	buf = kvmalloc(len, GFP_KERNEL);
2645	if (buf == NULL) {
2646	err = nfserr_jukebox;
2647	goto out;
2648	}
2649
2650	len = vfs_getxattr(&nop_mnt_idmap, dentry, name, buf, len);
2651	if (len <= 0) {
2652	kvfree(addr: buf);
2653	buf = NULL;
2654	err = nfsd_xattr_errno(err: len);
2655	}
2656
2657	*lenp = len;
2658	*bufp = buf;
2659
2660	out:
2661	inode_unlock_shared(inode);
2662
2663	return err;
2664	}
2665
2666	/*
2667	* Retrieve the xattr names. Since we can't know how many are
2668	* user extended attributes, we must get all attributes here,
2669	* and have the XDR encode filter out the "user." ones.
2670	*
2671	* While this could always just allocate an XATTR_LIST_MAX
2672	* buffer, that's a waste, so do a probe + allocate. To
2673	* avoid any changes between the probe and allocate, wrap
2674	* this in inode_lock.
2675	*/
2676	__be32
2677	nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
2678	int *lenp)
2679	{
2680	ssize_t len;
2681	__be32 err;
2682	char *buf;
2683	struct inode *inode;
2684	struct dentry *dentry;
2685
2686	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
2687	if (err)
2688	return err;
2689
2690	dentry = fhp->fh_dentry;
2691	inode = d_inode(dentry);
2692	*lenp = 0;
2693
2694	inode_lock_shared(inode);
2695
2696	len = vfs_listxattr(d: dentry, NULL, size: 0);
2697	if (len <= 0) {
2698	err = nfsd_xattr_errno(err: len);
2699	goto out;
2700	}
2701
2702	if (len > XATTR_LIST_MAX) {
2703	err = nfserr_xattr2big;
2704	goto out;
2705	}
2706
2707	buf = kvmalloc(len, GFP_KERNEL);
2708	if (buf == NULL) {
2709	err = nfserr_jukebox;
2710	goto out;
2711	}
2712
2713	len = vfs_listxattr(d: dentry, list: buf, size: len);
2714	if (len <= 0) {
2715	kvfree(addr: buf);
2716	err = nfsd_xattr_errno(err: len);
2717	goto out;
2718	}
2719
2720	*lenp = len;
2721	*bufp = buf;
2722
2723	err = nfs_ok;
2724	out:
2725	inode_unlock_shared(inode);
2726
2727	return err;
2728	}
2729
2730	/**
2731	* nfsd_removexattr - Remove an extended attribute
2732	* @rqstp: RPC transaction being executed
2733	* @fhp: NFS filehandle of object with xattr to remove
2734	* @name: name of xattr to remove (NUL-terminate)
2735	*
2736	* Pass in a NULL pointer for delegated_inode, and let the client deal
2737	* with NFS4ERR_DELAY (same as with e.g. setattr and remove).
2738	*
2739	* Returns nfs_ok on success, or an nfsstat in network byte order.
2740	*/
2741	__be32
2742	nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
2743	{
2744	__be32 err;
2745	int ret;
2746
2747	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2748	if (err)
2749	return err;
2750
2751	ret = fh_want_write(fhp);
2752	if (ret)
2753	return nfserrno(errno: ret);
2754
2755	inode_lock(inode: fhp->fh_dentry->d_inode);
2756	err = fh_fill_pre_attrs(fhp);
2757	if (err != nfs_ok)
2758	goto out_unlock;
2759	ret = __vfs_removexattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
2760	name, NULL);
2761	err = nfsd_xattr_errno(err: ret);
2762	fh_fill_post_attrs(fhp);
2763	out_unlock:
2764	inode_unlock(inode: fhp->fh_dentry->d_inode);
2765	fh_drop_write(fhp);
2766
2767	return err;
2768	}
2769
2770	__be32
2771	nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
2772	void *buf, u32 len, u32 flags)
2773	{
2774	__be32 err;
2775	int ret;
2776
2777	err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
2778	if (err)
2779	return err;
2780
2781	ret = fh_want_write(fhp);
2782	if (ret)
2783	return nfserrno(errno: ret);
2784	inode_lock(inode: fhp->fh_dentry->d_inode);
2785	err = fh_fill_pre_attrs(fhp);
2786	if (err != nfs_ok)
2787	goto out_unlock;
2788	ret = __vfs_setxattr_locked(&nop_mnt_idmap, fhp->fh_dentry,
2789	name, buf, len, flags, NULL);
2790	fh_fill_post_attrs(fhp);
2791	err = nfsd_xattr_errno(err: ret);
2792	out_unlock:
2793	inode_unlock(inode: fhp->fh_dentry->d_inode);
2794	fh_drop_write(fhp);
2795	return err;
2796	}
2797	#endif
2798
2799	/*
2800	* Check for a user's access permissions to this inode.
2801	*/
2802	__be32
2803	nfsd_permission(struct svc_cred *cred, struct svc_export *exp,
2804	struct dentry *dentry, int acc)
2805	{
2806	struct inode *inode = d_inode(dentry);
2807	int err;
2808
2809	if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2810	return 0;
2811	#if 0
2812	dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2813	acc,
2814	(acc & NFSD_MAY_READ)? " read" : "",
2815	(acc & NFSD_MAY_WRITE)? " write" : "",
2816	(acc & NFSD_MAY_EXEC)? " exec" : "",
2817	(acc & NFSD_MAY_SATTR)? " sattr" : "",
2818	(acc & NFSD_MAY_TRUNC)? " trunc" : "",
2819	(acc & NFSD_MAY_NLM)? " nlm" : "",
2820	(acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2821	inode->i_mode,
2822	IS_IMMUTABLE(inode)? " immut" : "",
2823	IS_APPEND(inode)? " append" : "",
2824	__mnt_is_readonly(exp->ex_path.mnt)? " ro" : "");
2825	dprintk(" owner %d/%d user %d/%d\n",
2826	inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2827	#endif
2828
2829	/* Normally we reject any write/sattr etc access on a read-only file
2830	* system. But if it is IRIX doing check on write-access for a
2831	* device special file, we ignore rofs.
2832	*/
2833	if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2834	if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2835	if (exp_rdonly(cred, exp) ||
2836	__mnt_is_readonly(mnt: exp->ex_path.mnt))
2837	return nfserr_rofs;
2838	if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2839	return nfserr_perm;
2840	}
2841	if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2842	return nfserr_perm;
2843
2844	/*
2845	* The file owner always gets access permission for accesses that
2846	* would normally be checked at open time. This is to make
2847	* file access work even when the client has done a fchmod(fd, 0).
2848	*
2849	* However, `cp foo bar' should fail nevertheless when bar is
2850	* readonly. A sensible way to do this might be to reject all
2851	* attempts to truncate a read-only file, because a creat() call
2852	* always implies file truncation.
2853	* ... but this isn't really fair. A process may reasonably call
2854	* ftruncate on an open file descriptor on a file with perm 000.
2855	* We must trust the client to do permission checking - using "ACCESS"
2856	* with NFSv3.
2857	*/
2858	if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2859	uid_eq(left: inode->i_uid, current_fsuid()))
2860	return 0;
2861
2862	/* This assumes NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2863	err = inode_permission(&nop_mnt_idmap, inode,
2864	acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
2865
2866	/* Allow read access to binaries even when mode 111 */
2867	if (err == -EACCES && S_ISREG(inode->i_mode) &&
2868	(((acc & NFSD_MAY_MASK) == NFSD_MAY_READ) &&
2869	(acc & (NFSD_MAY_OWNER_OVERRIDE | NFSD_MAY_READ_IF_EXEC))))
2870	err = inode_permission(&nop_mnt_idmap, inode, MAY_EXEC);
2871
2872	return err? nfserrno(errno: err) : 0;
2873	}
2874