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Linux/fs/nfsd/vfs.c

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  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/ima.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 #ifdef CONFIG_NFSD_V3
 36 #include "xdr3.h"
 37 #endif /* CONFIG_NFSD_V3 */
 38 
 39 #ifdef CONFIG_NFSD_V4
 40 #include "../internal.h"
 41 #include "acl.h"
 42 #include "idmap.h"
 43 #endif /* CONFIG_NFSD_V4 */
 44 
 45 #include "nfsd.h"
 46 #include "vfs.h"
 47 #include "trace.h"
 48 
 49 #define NFSDDBG_FACILITY                NFSDDBG_FILEOP
 50 
 51 
 52 /*
 53  * This is a cache of readahead params that help us choose the proper
 54  * readahead strategy. Initially, we set all readahead parameters to 0
 55  * and let the VFS handle things.
 56  * If you increase the number of cached files very much, you'll need to
 57  * add a hash table here.
 58  */
 59 struct raparms {
 60         struct raparms          *p_next;
 61         unsigned int            p_count;
 62         ino_t                   p_ino;
 63         dev_t                   p_dev;
 64         int                     p_set;
 65         struct file_ra_state    p_ra;
 66         unsigned int            p_hindex;
 67 };
 68 
 69 struct raparm_hbucket {
 70         struct raparms          *pb_head;
 71         spinlock_t              pb_lock;
 72 } ____cacheline_aligned_in_smp;
 73 
 74 #define RAPARM_HASH_BITS        4
 75 #define RAPARM_HASH_SIZE        (1<<RAPARM_HASH_BITS)
 76 #define RAPARM_HASH_MASK        (RAPARM_HASH_SIZE-1)
 77 static struct raparm_hbucket    raparm_hash[RAPARM_HASH_SIZE];
 78 
 79 /* 
 80  * Called from nfsd_lookup and encode_dirent. Check if we have crossed 
 81  * a mount point.
 82  * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
 83  *  or nfs_ok having possibly changed *dpp and *expp
 84  */
 85 int
 86 nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp, 
 87                         struct svc_export **expp)
 88 {
 89         struct svc_export *exp = *expp, *exp2 = NULL;
 90         struct dentry *dentry = *dpp;
 91         struct path path = {.mnt = mntget(exp->ex_path.mnt),
 92                             .dentry = dget(dentry)};
 93         int err = 0;
 94 
 95         err = follow_down(&path);
 96         if (err < 0)
 97                 goto out;
 98         if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
 99             nfsd_mountpoint(dentry, exp) == 2) {
100                 /* This is only a mountpoint in some other namespace */
101                 path_put(&path);
102                 goto out;
103         }
104 
105         exp2 = rqst_exp_get_by_name(rqstp, &path);
106         if (IS_ERR(exp2)) {
107                 err = PTR_ERR(exp2);
108                 /*
109                  * We normally allow NFS clients to continue
110                  * "underneath" a mountpoint that is not exported.
111                  * The exception is V4ROOT, where no traversal is ever
112                  * allowed without an explicit export of the new
113                  * directory.
114                  */
115                 if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
116                         err = 0;
117                 path_put(&path);
118                 goto out;
119         }
120         if (nfsd_v4client(rqstp) ||
121                 (exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
122                 /* successfully crossed mount point */
123                 /*
124                  * This is subtle: path.dentry is *not* on path.mnt
125                  * at this point.  The only reason we are safe is that
126                  * original mnt is pinned down by exp, so we should
127                  * put path *before* putting exp
128                  */
129                 *dpp = path.dentry;
130                 path.dentry = dentry;
131                 *expp = exp2;
132                 exp2 = exp;
133         }
134         path_put(&path);
135         exp_put(exp2);
136 out:
137         return err;
138 }
139 
140 static void follow_to_parent(struct path *path)
141 {
142         struct dentry *dp;
143 
144         while (path->dentry == path->mnt->mnt_root && follow_up(path))
145                 ;
146         dp = dget_parent(path->dentry);
147         dput(path->dentry);
148         path->dentry = dp;
149 }
150 
151 static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
152 {
153         struct svc_export *exp2;
154         struct path path = {.mnt = mntget((*exp)->ex_path.mnt),
155                             .dentry = dget(dparent)};
156 
157         follow_to_parent(&path);
158 
159         exp2 = rqst_exp_parent(rqstp, &path);
160         if (PTR_ERR(exp2) == -ENOENT) {
161                 *dentryp = dget(dparent);
162         } else if (IS_ERR(exp2)) {
163                 path_put(&path);
164                 return PTR_ERR(exp2);
165         } else {
166                 *dentryp = dget(path.dentry);
167                 exp_put(*exp);
168                 *exp = exp2;
169         }
170         path_put(&path);
171         return 0;
172 }
173 
174 /*
175  * For nfsd purposes, we treat V4ROOT exports as though there was an
176  * export at *every* directory.
177  * We return:
178  * '1' if this dentry *must* be an export point,
179  * '2' if it might be, if there is really a mount here, and
180  * '' if there is no chance of an export point here.
181  */
182 int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
183 {
184         if (!d_inode(dentry))
185                 return 0;
186         if (exp->ex_flags & NFSEXP_V4ROOT)
187                 return 1;
188         if (nfsd4_is_junction(dentry))
189                 return 1;
190         if (d_mountpoint(dentry))
191                 /*
192                  * Might only be a mountpoint in a different namespace,
193                  * but we need to check.
194                  */
195                 return 2;
196         return 0;
197 }
198 
199 __be32
200 nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
201                    const char *name, unsigned int len,
202                    struct svc_export **exp_ret, struct dentry **dentry_ret)
203 {
204         struct svc_export       *exp;
205         struct dentry           *dparent;
206         struct dentry           *dentry;
207         int                     host_err;
208 
209         dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
210 
211         dparent = fhp->fh_dentry;
212         exp = exp_get(fhp->fh_export);
213 
214         /* Lookup the name, but don't follow links */
215         if (isdotent(name, len)) {
216                 if (len==1)
217                         dentry = dget(dparent);
218                 else if (dparent != exp->ex_path.dentry)
219                         dentry = dget_parent(dparent);
220                 else if (!EX_NOHIDE(exp) && !nfsd_v4client(rqstp))
221                         dentry = dget(dparent); /* .. == . just like at / */
222                 else {
223                         /* checking mountpoint crossing is very different when stepping up */
224                         host_err = nfsd_lookup_parent(rqstp, dparent, &exp, &dentry);
225                         if (host_err)
226                                 goto out_nfserr;
227                 }
228         } else {
229                 /*
230                  * In the nfsd4_open() case, this may be held across
231                  * subsequent open and delegation acquisition which may
232                  * need to take the child's i_mutex:
233                  */
234                 fh_lock_nested(fhp, I_MUTEX_PARENT);
235                 dentry = lookup_one_len(name, dparent, len);
236                 host_err = PTR_ERR(dentry);
237                 if (IS_ERR(dentry))
238                         goto out_nfserr;
239                 if (nfsd_mountpoint(dentry, exp)) {
240                         /*
241                          * We don't need the i_mutex after all.  It's
242                          * still possible we could open this (regular
243                          * files can be mountpoints too), but the
244                          * i_mutex is just there to prevent renames of
245                          * something that we might be about to delegate,
246                          * and a mountpoint won't be renamed:
247                          */
248                         fh_unlock(fhp);
249                         if ((host_err = nfsd_cross_mnt(rqstp, &dentry, &exp))) {
250                                 dput(dentry);
251                                 goto out_nfserr;
252                         }
253                 }
254         }
255         *dentry_ret = dentry;
256         *exp_ret = exp;
257         return 0;
258 
259 out_nfserr:
260         exp_put(exp);
261         return nfserrno(host_err);
262 }
263 
264 /*
265  * Look up one component of a pathname.
266  * N.B. After this call _both_ fhp and resfh need an fh_put
267  *
268  * If the lookup would cross a mountpoint, and the mounted filesystem
269  * is exported to the client with NFSEXP_NOHIDE, then the lookup is
270  * accepted as it stands and the mounted directory is
271  * returned. Otherwise the covered directory is returned.
272  * NOTE: this mountpoint crossing is not supported properly by all
273  *   clients and is explicitly disallowed for NFSv3
274  *      NeilBrown <neilb@cse.unsw.edu.au>
275  */
276 __be32
277 nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
278                                 unsigned int len, struct svc_fh *resfh)
279 {
280         struct svc_export       *exp;
281         struct dentry           *dentry;
282         __be32 err;
283 
284         err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
285         if (err)
286                 return err;
287         err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
288         if (err)
289                 return err;
290         err = check_nfsd_access(exp, rqstp);
291         if (err)
292                 goto out;
293         /*
294          * Note: we compose the file handle now, but as the
295          * dentry may be negative, it may need to be updated.
296          */
297         err = fh_compose(resfh, exp, dentry, fhp);
298         if (!err && d_really_is_negative(dentry))
299                 err = nfserr_noent;
300 out:
301         dput(dentry);
302         exp_put(exp);
303         return err;
304 }
305 
306 /*
307  * Commit metadata changes to stable storage.
308  */
309 static int
310 commit_metadata(struct svc_fh *fhp)
311 {
312         struct inode *inode = d_inode(fhp->fh_dentry);
313         const struct export_operations *export_ops = inode->i_sb->s_export_op;
314 
315         if (!EX_ISSYNC(fhp->fh_export))
316                 return 0;
317 
318         if (export_ops->commit_metadata)
319                 return export_ops->commit_metadata(inode);
320         return sync_inode_metadata(inode, 1);
321 }
322 
323 /*
324  * Go over the attributes and take care of the small differences between
325  * NFS semantics and what Linux expects.
326  */
327 static void
328 nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
329 {
330         /* sanitize the mode change */
331         if (iap->ia_valid & ATTR_MODE) {
332                 iap->ia_mode &= S_IALLUGO;
333                 iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
334         }
335 
336         /* Revoke setuid/setgid on chown */
337         if (!S_ISDIR(inode->i_mode) &&
338             ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
339                 iap->ia_valid |= ATTR_KILL_PRIV;
340                 if (iap->ia_valid & ATTR_MODE) {
341                         /* we're setting mode too, just clear the s*id bits */
342                         iap->ia_mode &= ~S_ISUID;
343                         if (iap->ia_mode & S_IXGRP)
344                                 iap->ia_mode &= ~S_ISGID;
345                 } else {
346                         /* set ATTR_KILL_* bits and let VFS handle it */
347                         iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
348                 }
349         }
350 }
351 
352 static __be32
353 nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
354                 struct iattr *iap)
355 {
356         struct inode *inode = d_inode(fhp->fh_dentry);
357         int host_err;
358 
359         if (iap->ia_size < inode->i_size) {
360                 __be32 err;
361 
362                 err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
363                                 NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
364                 if (err)
365                         return err;
366         }
367 
368         host_err = get_write_access(inode);
369         if (host_err)
370                 goto out_nfserrno;
371 
372         host_err = locks_verify_truncate(inode, NULL, iap->ia_size);
373         if (host_err)
374                 goto out_put_write_access;
375         return 0;
376 
377 out_put_write_access:
378         put_write_access(inode);
379 out_nfserrno:
380         return nfserrno(host_err);
381 }
382 
383 /*
384  * Set various file attributes.  After this call fhp needs an fh_put.
385  */
386 __be32
387 nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
388              int check_guard, time_t guardtime)
389 {
390         struct dentry   *dentry;
391         struct inode    *inode;
392         int             accmode = NFSD_MAY_SATTR;
393         umode_t         ftype = 0;
394         __be32          err;
395         int             host_err;
396         bool            get_write_count;
397         bool            size_change = (iap->ia_valid & ATTR_SIZE);
398 
399         if (iap->ia_valid & ATTR_SIZE) {
400                 accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
401                 ftype = S_IFREG;
402         }
403 
404         /*
405          * If utimes(2) and friends are called with times not NULL, we should
406          * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
407          * will return EACCESS, when the caller's effective UID does not match
408          * the owner of the file, and the caller is not privileged. In this
409          * situation, we should return EPERM(notify_change will return this).
410          */
411         if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
412                 accmode |= NFSD_MAY_OWNER_OVERRIDE;
413                 if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
414                         accmode |= NFSD_MAY_WRITE;
415         }
416 
417         /* Callers that do fh_verify should do the fh_want_write: */
418         get_write_count = !fhp->fh_dentry;
419 
420         /* Get inode */
421         err = fh_verify(rqstp, fhp, ftype, accmode);
422         if (err)
423                 return err;
424         if (get_write_count) {
425                 host_err = fh_want_write(fhp);
426                 if (host_err)
427                         goto out;
428         }
429 
430         dentry = fhp->fh_dentry;
431         inode = d_inode(dentry);
432 
433         /* Ignore any mode updates on symlinks */
434         if (S_ISLNK(inode->i_mode))
435                 iap->ia_valid &= ~ATTR_MODE;
436 
437         if (!iap->ia_valid)
438                 return 0;
439 
440         nfsd_sanitize_attrs(inode, iap);
441 
442         if (check_guard && guardtime != inode->i_ctime.tv_sec)
443                 return nfserr_notsync;
444 
445         /*
446          * The size case is special, it changes the file in addition to the
447          * attributes, and file systems don't expect it to be mixed with
448          * "random" attribute changes.  We thus split out the size change
449          * into a separate call to ->setattr, and do the rest as a separate
450          * setattr call.
451          */
452         if (size_change) {
453                 err = nfsd_get_write_access(rqstp, fhp, iap);
454                 if (err)
455                         return err;
456         }
457 
458         fh_lock(fhp);
459         if (size_change) {
460                 /*
461                  * RFC5661, Section 18.30.4:
462                  *   Changing the size of a file with SETATTR indirectly
463                  *   changes the time_modify and change attributes.
464                  *
465                  * (and similar for the older RFCs)
466                  */
467                 struct iattr size_attr = {
468                         .ia_valid       = ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
469                         .ia_size        = iap->ia_size,
470                 };
471 
472                 host_err = notify_change(dentry, &size_attr, NULL);
473                 if (host_err)
474                         goto out_unlock;
475                 iap->ia_valid &= ~ATTR_SIZE;
476 
477                 /*
478                  * Avoid the additional setattr call below if the only other
479                  * attribute that the client sends is the mtime, as we update
480                  * it as part of the size change above.
481                  */
482                 if ((iap->ia_valid & ~ATTR_MTIME) == 0)
483                         goto out_unlock;
484         }
485 
486         iap->ia_valid |= ATTR_CTIME;
487         host_err = notify_change(dentry, iap, NULL);
488 
489 out_unlock:
490         fh_unlock(fhp);
491         if (size_change)
492                 put_write_access(inode);
493 out:
494         if (!host_err)
495                 host_err = commit_metadata(fhp);
496         return nfserrno(host_err);
497 }
498 
499 #if defined(CONFIG_NFSD_V4)
500 /*
501  * NFS junction information is stored in an extended attribute.
502  */
503 #define NFSD_JUNCTION_XATTR_NAME        XATTR_TRUSTED_PREFIX "junction.nfs"
504 
505 /**
506  * nfsd4_is_junction - Test if an object could be an NFS junction
507  *
508  * @dentry: object to test
509  *
510  * Returns 1 if "dentry" appears to contain NFS junction information.
511  * Otherwise 0 is returned.
512  */
513 int nfsd4_is_junction(struct dentry *dentry)
514 {
515         struct inode *inode = d_inode(dentry);
516 
517         if (inode == NULL)
518                 return 0;
519         if (inode->i_mode & S_IXUGO)
520                 return 0;
521         if (!(inode->i_mode & S_ISVTX))
522                 return 0;
523         if (vfs_getxattr(dentry, NFSD_JUNCTION_XATTR_NAME, NULL, 0) <= 0)
524                 return 0;
525         return 1;
526 }
527 #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
528 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
529                 struct xdr_netobj *label)
530 {
531         __be32 error;
532         int host_error;
533         struct dentry *dentry;
534 
535         error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, NFSD_MAY_SATTR);
536         if (error)
537                 return error;
538 
539         dentry = fhp->fh_dentry;
540 
541         inode_lock(d_inode(dentry));
542         host_error = security_inode_setsecctx(dentry, label->data, label->len);
543         inode_unlock(d_inode(dentry));
544         return nfserrno(host_error);
545 }
546 #else
547 __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
548                 struct xdr_netobj *label)
549 {
550         return nfserr_notsupp;
551 }
552 #endif
553 
554 __be32 nfsd4_clone_file_range(struct file *src, u64 src_pos, struct file *dst,
555                 u64 dst_pos, u64 count)
556 {
557         loff_t cloned;
558 
559         cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
560         if (cloned < 0)
561                 return nfserrno(cloned);
562         if (count && cloned != count)
563                 return nfserrno(-EINVAL);
564         return 0;
565 }
566 
567 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
568                              u64 dst_pos, u64 count)
569 {
570 
571         /*
572          * Limit copy to 4MB to prevent indefinitely blocking an nfsd
573          * thread and client rpc slot.  The choice of 4MB is somewhat
574          * arbitrary.  We might instead base this on r/wsize, or make it
575          * tunable, or use a time instead of a byte limit, or implement
576          * asynchronous copy.  In theory a client could also recognize a
577          * limit like this and pipeline multiple COPY requests.
578          */
579         count = min_t(u64, count, 1 << 22);
580         return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
581 }
582 
583 __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
584                            struct file *file, loff_t offset, loff_t len,
585                            int flags)
586 {
587         int error;
588 
589         if (!S_ISREG(file_inode(file)->i_mode))
590                 return nfserr_inval;
591 
592         error = vfs_fallocate(file, flags, offset, len);
593         if (!error)
594                 error = commit_metadata(fhp);
595 
596         return nfserrno(error);
597 }
598 #endif /* defined(CONFIG_NFSD_V4) */
599 
600 #ifdef CONFIG_NFSD_V3
601 /*
602  * Check server access rights to a file system object
603  */
604 struct accessmap {
605         u32             access;
606         int             how;
607 };
608 static struct accessmap nfs3_regaccess[] = {
609     {   NFS3_ACCESS_READ,       NFSD_MAY_READ                   },
610     {   NFS3_ACCESS_EXECUTE,    NFSD_MAY_EXEC                   },
611     {   NFS3_ACCESS_MODIFY,     NFSD_MAY_WRITE|NFSD_MAY_TRUNC   },
612     {   NFS3_ACCESS_EXTEND,     NFSD_MAY_WRITE                  },
613 
614     {   0,                      0                               }
615 };
616 
617 static struct accessmap nfs3_diraccess[] = {
618     {   NFS3_ACCESS_READ,       NFSD_MAY_READ                   },
619     {   NFS3_ACCESS_LOOKUP,     NFSD_MAY_EXEC                   },
620     {   NFS3_ACCESS_MODIFY,     NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
621     {   NFS3_ACCESS_EXTEND,     NFSD_MAY_EXEC|NFSD_MAY_WRITE    },
622     {   NFS3_ACCESS_DELETE,     NFSD_MAY_REMOVE                 },
623 
624     {   0,                      0                               }
625 };
626 
627 static struct accessmap nfs3_anyaccess[] = {
628         /* Some clients - Solaris 2.6 at least, make an access call
629          * to the server to check for access for things like /dev/null
630          * (which really, the server doesn't care about).  So
631          * We provide simple access checking for them, looking
632          * mainly at mode bits, and we make sure to ignore read-only
633          * filesystem checks
634          */
635     {   NFS3_ACCESS_READ,       NFSD_MAY_READ                   },
636     {   NFS3_ACCESS_EXECUTE,    NFSD_MAY_EXEC                   },
637     {   NFS3_ACCESS_MODIFY,     NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS    },
638     {   NFS3_ACCESS_EXTEND,     NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS    },
639 
640     {   0,                      0                               }
641 };
642 
643 __be32
644 nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
645 {
646         struct accessmap        *map;
647         struct svc_export       *export;
648         struct dentry           *dentry;
649         u32                     query, result = 0, sresult = 0;
650         __be32                  error;
651 
652         error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
653         if (error)
654                 goto out;
655 
656         export = fhp->fh_export;
657         dentry = fhp->fh_dentry;
658 
659         if (d_is_reg(dentry))
660                 map = nfs3_regaccess;
661         else if (d_is_dir(dentry))
662                 map = nfs3_diraccess;
663         else
664                 map = nfs3_anyaccess;
665 
666 
667         query = *access;
668         for  (; map->access; map++) {
669                 if (map->access & query) {
670                         __be32 err2;
671 
672                         sresult |= map->access;
673 
674                         err2 = nfsd_permission(rqstp, export, dentry, map->how);
675                         switch (err2) {
676                         case nfs_ok:
677                                 result |= map->access;
678                                 break;
679                                 
680                         /* the following error codes just mean the access was not allowed,
681                          * rather than an error occurred */
682                         case nfserr_rofs:
683                         case nfserr_acces:
684                         case nfserr_perm:
685                                 /* simply don't "or" in the access bit. */
686                                 break;
687                         default:
688                                 error = err2;
689                                 goto out;
690                         }
691                 }
692         }
693         *access = result;
694         if (supported)
695                 *supported = sresult;
696 
697  out:
698         return error;
699 }
700 #endif /* CONFIG_NFSD_V3 */
701 
702 static int nfsd_open_break_lease(struct inode *inode, int access)
703 {
704         unsigned int mode;
705 
706         if (access & NFSD_MAY_NOT_BREAK_LEASE)
707                 return 0;
708         mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
709         return break_lease(inode, mode | O_NONBLOCK);
710 }
711 
712 /*
713  * Open an existing file or directory.
714  * The may_flags argument indicates the type of open (read/write/lock)
715  * and additional flags.
716  * N.B. After this call fhp needs an fh_put
717  */
718 __be32
719 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
720                         int may_flags, struct file **filp)
721 {
722         struct path     path;
723         struct inode    *inode;
724         struct file     *file;
725         int             flags = O_RDONLY|O_LARGEFILE;
726         __be32          err;
727         int             host_err = 0;
728 
729         validate_process_creds();
730 
731         /*
732          * If we get here, then the client has already done an "open",
733          * and (hopefully) checked permission - so allow OWNER_OVERRIDE
734          * in case a chmod has now revoked permission.
735          *
736          * Arguably we should also allow the owner override for
737          * directories, but we never have and it doesn't seem to have
738          * caused anyone a problem.  If we were to change this, note
739          * also that our filldir callbacks would need a variant of
740          * lookup_one_len that doesn't check permissions.
741          */
742         if (type == S_IFREG)
743                 may_flags |= NFSD_MAY_OWNER_OVERRIDE;
744         err = fh_verify(rqstp, fhp, type, may_flags);
745         if (err)
746                 goto out;
747 
748         path.mnt = fhp->fh_export->ex_path.mnt;
749         path.dentry = fhp->fh_dentry;
750         inode = d_inode(path.dentry);
751 
752         /* Disallow write access to files with the append-only bit set
753          * or any access when mandatory locking enabled
754          */
755         err = nfserr_perm;
756         if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
757                 goto out;
758         /*
759          * We must ignore files (but only files) which might have mandatory
760          * locks on them because there is no way to know if the accesser has
761          * the lock.
762          */
763         if (S_ISREG((inode)->i_mode) && mandatory_lock(inode))
764                 goto out;
765 
766         if (!inode->i_fop)
767                 goto out;
768 
769         host_err = nfsd_open_break_lease(inode, may_flags);
770         if (host_err) /* NOMEM or WOULDBLOCK */
771                 goto out_nfserr;
772 
773         if (may_flags & NFSD_MAY_WRITE) {
774                 if (may_flags & NFSD_MAY_READ)
775                         flags = O_RDWR|O_LARGEFILE;
776                 else
777                         flags = O_WRONLY|O_LARGEFILE;
778         }
779 
780         file = dentry_open(&path, flags, current_cred());
781         if (IS_ERR(file)) {
782                 host_err = PTR_ERR(file);
783                 goto out_nfserr;
784         }
785 
786         host_err = ima_file_check(file, may_flags);
787         if (host_err) {
788                 fput(file);
789                 goto out_nfserr;
790         }
791 
792         if (may_flags & NFSD_MAY_64BIT_COOKIE)
793                 file->f_mode |= FMODE_64BITHASH;
794         else
795                 file->f_mode |= FMODE_32BITHASH;
796 
797         *filp = file;
798 out_nfserr:
799         err = nfserrno(host_err);
800 out:
801         validate_process_creds();
802         return err;
803 }
804 
805 struct raparms *
806 nfsd_init_raparms(struct file *file)
807 {
808         struct inode *inode = file_inode(file);
809         dev_t dev = inode->i_sb->s_dev;
810         ino_t ino = inode->i_ino;
811         struct raparms  *ra, **rap, **frap = NULL;
812         int depth = 0;
813         unsigned int hash;
814         struct raparm_hbucket *rab;
815 
816         hash = jhash_2words(dev, ino, 0xfeedbeef) & RAPARM_HASH_MASK;
817         rab = &raparm_hash[hash];
818 
819         spin_lock(&rab->pb_lock);
820         for (rap = &rab->pb_head; (ra = *rap); rap = &ra->p_next) {
821                 if (ra->p_ino == ino && ra->p_dev == dev)
822                         goto found;
823                 depth++;
824                 if (ra->p_count == 0)
825                         frap = rap;
826         }
827         depth = nfsdstats.ra_size;
828         if (!frap) {    
829                 spin_unlock(&rab->pb_lock);
830                 return NULL;
831         }
832         rap = frap;
833         ra = *frap;
834         ra->p_dev = dev;
835         ra->p_ino = ino;
836         ra->p_set = 0;
837         ra->p_hindex = hash;
838 found:
839         if (rap != &rab->pb_head) {
840                 *rap = ra->p_next;
841                 ra->p_next   = rab->pb_head;
842                 rab->pb_head = ra;
843         }
844         ra->p_count++;
845         nfsdstats.ra_depth[depth*10/nfsdstats.ra_size]++;
846         spin_unlock(&rab->pb_lock);
847 
848         if (ra->p_set)
849                 file->f_ra = ra->p_ra;
850         return ra;
851 }
852 
853 void nfsd_put_raparams(struct file *file, struct raparms *ra)
854 {
855         struct raparm_hbucket *rab = &raparm_hash[ra->p_hindex];
856 
857         spin_lock(&rab->pb_lock);
858         ra->p_ra = file->f_ra;
859         ra->p_set = 1;
860         ra->p_count--;
861         spin_unlock(&rab->pb_lock);
862 }
863 
864 /*
865  * Grab and keep cached pages associated with a file in the svc_rqst
866  * so that they can be passed to the network sendmsg/sendpage routines
867  * directly. They will be released after the sending has completed.
868  */
869 static int
870 nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
871                   struct splice_desc *sd)
872 {
873         struct svc_rqst *rqstp = sd->u.data;
874         struct page **pp = rqstp->rq_next_page;
875         struct page *page = buf->page;
876         size_t size;
877 
878         size = sd->len;
879 
880         if (rqstp->rq_res.page_len == 0) {
881                 get_page(page);
882                 put_page(*rqstp->rq_next_page);
883                 *(rqstp->rq_next_page++) = page;
884                 rqstp->rq_res.page_base = buf->offset;
885                 rqstp->rq_res.page_len = size;
886         } else if (page != pp[-1]) {
887                 get_page(page);
888                 if (*rqstp->rq_next_page)
889                         put_page(*rqstp->rq_next_page);
890                 *(rqstp->rq_next_page++) = page;
891                 rqstp->rq_res.page_len += size;
892         } else
893                 rqstp->rq_res.page_len += size;
894 
895         return size;
896 }
897 
898 static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
899                                     struct splice_desc *sd)
900 {
901         return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
902 }
903 
904 static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
905                                struct file *file, loff_t offset,
906                                unsigned long *count, int host_err)
907 {
908         if (host_err >= 0) {
909                 nfsdstats.io_read += host_err;
910                 *count = host_err;
911                 fsnotify_access(file);
912                 trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
913                 return 0;
914         } else {
915                 trace_nfsd_read_err(rqstp, fhp, offset, host_err);
916                 return nfserrno(host_err);
917         }
918 }
919 
920 __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
921                         struct file *file, loff_t offset, unsigned long *count)
922 {
923         struct splice_desc sd = {
924                 .len            = 0,
925                 .total_len      = *count,
926                 .pos            = offset,
927                 .u.data         = rqstp,
928         };
929         int host_err;
930 
931         trace_nfsd_read_splice(rqstp, fhp, offset, *count);
932         rqstp->rq_next_page = rqstp->rq_respages + 1;
933         host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
934         return nfsd_finish_read(rqstp, fhp, file, offset, count, host_err);
935 }
936 
937 __be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
938                   struct file *file, loff_t offset,
939                   struct kvec *vec, int vlen, unsigned long *count)
940 {
941         struct iov_iter iter;
942         int host_err;
943 
944         trace_nfsd_read_vector(rqstp, fhp, offset, *count);
945         iov_iter_kvec(&iter, READ, vec, vlen, *count);
946         host_err = vfs_iter_read(file, &iter, &offset, 0);
947         return nfsd_finish_read(rqstp, fhp, file, offset, count, host_err);
948 }
949 
950 /*
951  * Gathered writes: If another process is currently writing to the file,
952  * there's a high chance this is another nfsd (triggered by a bulk write
953  * from a client's biod). Rather than syncing the file with each write
954  * request, we sleep for 10 msec.
955  *
956  * I don't know if this roughly approximates C. Juszak's idea of
957  * gathered writes, but it's a nice and simple solution (IMHO), and it
958  * seems to work:-)
959  *
960  * Note: we do this only in the NFSv2 case, since v3 and higher have a
961  * better tool (separate unstable writes and commits) for solving this
962  * problem.
963  */
964 static int wait_for_concurrent_writes(struct file *file)
965 {
966         struct inode *inode = file_inode(file);
967         static ino_t last_ino;
968         static dev_t last_dev;
969         int err = 0;
970 
971         if (atomic_read(&inode->i_writecount) > 1
972             || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
973                 dprintk("nfsd: write defer %d\n", task_pid_nr(current));
974                 msleep(10);
975                 dprintk("nfsd: write resume %d\n", task_pid_nr(current));
976         }
977 
978         if (inode->i_state & I_DIRTY) {
979                 dprintk("nfsd: write sync %d\n", task_pid_nr(current));
980                 err = vfs_fsync(file, 0);
981         }
982         last_ino = inode->i_ino;
983         last_dev = inode->i_sb->s_dev;
984         return err;
985 }
986 
987 __be32
988 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
989                                 loff_t offset, struct kvec *vec, int vlen,
990                                 unsigned long *cnt, int stable)
991 {
992         struct svc_export       *exp;
993         struct iov_iter         iter;
994         __be32                  nfserr;
995         int                     host_err;
996         int                     use_wgather;
997         loff_t                  pos = offset;
998         unsigned int            pflags = current->flags;
999         rwf_t                   flags = 0;
1000 
1001         trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
1002 
1003         if (test_bit(RQ_LOCAL, &rqstp->rq_flags))
1004                 /*
1005                  * We want less throttling in balance_dirty_pages()
1006                  * and shrink_inactive_list() so that nfs to
1007                  * localhost doesn't cause nfsd to lock up due to all
1008                  * the client's dirty pages or its congested queue.
1009                  */
1010                 current->flags |= PF_LESS_THROTTLE;
1011 
1012         exp = fhp->fh_export;
1013         use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
1014 
1015         if (!EX_ISSYNC(exp))
1016                 stable = NFS_UNSTABLE;
1017 
1018         if (stable && !use_wgather)
1019                 flags |= RWF_SYNC;
1020 
1021         iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
1022         host_err = vfs_iter_write(file, &iter, &pos, flags);
1023         if (host_err < 0)
1024                 goto out_nfserr;
1025         nfsdstats.io_write += *cnt;
1026         fsnotify_modify(file);
1027 
1028         if (stable && use_wgather)
1029                 host_err = wait_for_concurrent_writes(file);
1030 
1031 out_nfserr:
1032         if (host_err >= 0) {
1033                 trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
1034                 nfserr = nfs_ok;
1035         } else {
1036                 trace_nfsd_write_err(rqstp, fhp, offset, host_err);
1037                 nfserr = nfserrno(host_err);
1038         }
1039         if (test_bit(RQ_LOCAL, &rqstp->rq_flags))
1040                 current_restore_flags(pflags, PF_LESS_THROTTLE);
1041         return nfserr;
1042 }
1043 
1044 /*
1045  * Read data from a file. count must contain the requested read count
1046  * on entry. On return, *count contains the number of bytes actually read.
1047  * N.B. After this call fhp needs an fh_put
1048  */
1049 __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
1050         loff_t offset, struct kvec *vec, int vlen, unsigned long *count)
1051 {
1052         struct file *file;
1053         struct raparms  *ra;
1054         __be32 err;
1055 
1056         trace_nfsd_read_start(rqstp, fhp, offset, *count);
1057         err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_READ, &file);
1058         if (err)
1059                 return err;
1060 
1061         ra = nfsd_init_raparms(file);
1062 
1063         if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
1064                 err = nfsd_splice_read(rqstp, fhp, file, offset, count);
1065         else
1066                 err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count);
1067 
1068         if (ra)
1069                 nfsd_put_raparams(file, ra);
1070         fput(file);
1071 
1072         trace_nfsd_read_done(rqstp, fhp, offset, *count);
1073 
1074         return err;
1075 }
1076 
1077 /*
1078  * Write data to a file.
1079  * The stable flag requests synchronous writes.
1080  * N.B. After this call fhp needs an fh_put
1081  */
1082 __be32
1083 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
1084            struct kvec *vec, int vlen, unsigned long *cnt, int stable)
1085 {
1086         struct file *file = NULL;
1087         __be32 err = 0;
1088 
1089         trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
1090 
1091         err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_WRITE, &file);
1092         if (err)
1093                 goto out;
1094 
1095         err = nfsd_vfs_write(rqstp, fhp, file, offset, vec, vlen, cnt, stable);
1096         fput(file);
1097 out:
1098         trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
1099         return err;
1100 }
1101 
1102 #ifdef CONFIG_NFSD_V3
1103 /*
1104  * Commit all pending writes to stable storage.
1105  *
1106  * Note: we only guarantee that data that lies within the range specified
1107  * by the 'offset' and 'count' parameters will be synced.
1108  *
1109  * Unfortunately we cannot lock the file to make sure we return full WCC
1110  * data to the client, as locking happens lower down in the filesystem.
1111  */
1112 __be32
1113 nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp,
1114                loff_t offset, unsigned long count)
1115 {
1116         struct file     *file;
1117         loff_t          end = LLONG_MAX;
1118         __be32          err = nfserr_inval;
1119 
1120         if (offset < 0)
1121                 goto out;
1122         if (count != 0) {
1123                 end = offset + (loff_t)count - 1;
1124                 if (end < offset)
1125                         goto out;
1126         }
1127 
1128         err = nfsd_open(rqstp, fhp, S_IFREG,
1129                         NFSD_MAY_WRITE|NFSD_MAY_NOT_BREAK_LEASE, &file);
1130         if (err)
1131                 goto out;
1132         if (EX_ISSYNC(fhp->fh_export)) {
1133                 int err2 = vfs_fsync_range(file, offset, end, 0);
1134 
1135                 if (err2 != -EINVAL)
1136                         err = nfserrno(err2);
1137                 else
1138                         err = nfserr_notsupp;
1139         }
1140 
1141         fput(file);
1142 out:
1143         return err;
1144 }
1145 #endif /* CONFIG_NFSD_V3 */
1146 
1147 static __be32
1148 nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *resfhp,
1149                         struct iattr *iap)
1150 {
1151         /*
1152          * Mode has already been set earlier in create:
1153          */
1154         iap->ia_valid &= ~ATTR_MODE;
1155         /*
1156          * Setting uid/gid works only for root.  Irix appears to
1157          * send along the gid on create when it tries to implement
1158          * setgid directories via NFS:
1159          */
1160         if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
1161                 iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
1162         if (iap->ia_valid)
1163                 return nfsd_setattr(rqstp, resfhp, iap, 0, (time_t)0);
1164         /* Callers expect file metadata to be committed here */
1165         return nfserrno(commit_metadata(resfhp));
1166 }
1167 
1168 /* HPUX client sometimes creates a file in mode 000, and sets size to 0.
1169  * setting size to 0 may fail for some specific file systems by the permission
1170  * checking which requires WRITE permission but the mode is 000.
1171  * we ignore the resizing(to 0) on the just new created file, since the size is
1172  * 0 after file created.
1173  *
1174  * call this only after vfs_create() is called.
1175  * */
1176 static void
1177 nfsd_check_ignore_resizing(struct iattr *iap)
1178 {
1179         if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
1180                 iap->ia_valid &= ~ATTR_SIZE;
1181 }
1182 
1183 /* The parent directory should already be locked: */
1184 __be32
1185 nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
1186                 char *fname, int flen, struct iattr *iap,
1187                 int type, dev_t rdev, struct svc_fh *resfhp)
1188 {
1189         struct dentry   *dentry, *dchild;
1190         struct inode    *dirp;
1191         __be32          err;
1192         __be32          err2;
1193         int             host_err;
1194 
1195         dentry = fhp->fh_dentry;
1196         dirp = d_inode(dentry);
1197 
1198         dchild = dget(resfhp->fh_dentry);
1199         if (!fhp->fh_locked) {
1200                 WARN_ONCE(1, "nfsd_create: parent %pd2 not locked!\n",
1201                                 dentry);
1202                 err = nfserr_io;
1203                 goto out;
1204         }
1205 
1206         err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
1207         if (err)
1208                 goto out;
1209 
1210         if (!(iap->ia_valid & ATTR_MODE))
1211                 iap->ia_mode = 0;
1212         iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
1213 
1214         err = 0;
1215         host_err = 0;
1216         switch (type) {
1217         case S_IFREG:
1218                 host_err = vfs_create(dirp, dchild, iap->ia_mode, true);
1219                 if (!host_err)
1220                         nfsd_check_ignore_resizing(iap);
1221                 break;
1222         case S_IFDIR:
1223                 host_err = vfs_mkdir(dirp, dchild, iap->ia_mode);
1224                 if (!host_err && unlikely(d_unhashed(dchild))) {
1225                         struct dentry *d;
1226                         d = lookup_one_len(dchild->d_name.name,
1227                                            dchild->d_parent,
1228                                            dchild->d_name.len);
1229                         if (IS_ERR(d)) {
1230                                 host_err = PTR_ERR(d);
1231                                 break;
1232                         }
1233                         if (unlikely(d_is_negative(d))) {
1234                                 dput(d);
1235                                 err = nfserr_serverfault;
1236                                 goto out;
1237                         }
1238                         dput(resfhp->fh_dentry);
1239                         resfhp->fh_dentry = dget(d);
1240                         err = fh_update(resfhp);
1241                         dput(dchild);
1242                         dchild = d;
1243                         if (err)
1244                                 goto out;
1245                 }
1246                 break;
1247         case S_IFCHR:
1248         case S_IFBLK:
1249         case S_IFIFO:
1250         case S_IFSOCK:
1251                 host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
1252                 break;
1253         default:
1254                 printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
1255                        type);
1256                 host_err = -EINVAL;
1257         }
1258         if (host_err < 0)
1259                 goto out_nfserr;
1260 
1261         err = nfsd_create_setattr(rqstp, resfhp, iap);
1262 
1263         /*
1264          * nfsd_create_setattr already committed the child.  Transactional
1265          * filesystems had a chance to commit changes for both parent and
1266          * child simultaneously making the following commit_metadata a
1267          * noop.
1268          */
1269         err2 = nfserrno(commit_metadata(fhp));
1270         if (err2)
1271                 err = err2;
1272         /*
1273          * Update the file handle to get the new inode info.
1274          */
1275         if (!err)
1276                 err = fh_update(resfhp);
1277 out:
1278         dput(dchild);
1279         return err;
1280 
1281 out_nfserr:
1282         err = nfserrno(host_err);
1283         goto out;
1284 }
1285 
1286 /*
1287  * Create a filesystem object (regular, directory, special).
1288  * Note that the parent directory is left locked.
1289  *
1290  * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
1291  */
1292 __be32
1293 nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1294                 char *fname, int flen, struct iattr *iap,
1295                 int type, dev_t rdev, struct svc_fh *resfhp)
1296 {
1297         struct dentry   *dentry, *dchild = NULL;
1298         __be32          err;
1299         int             host_err;
1300 
1301         if (isdotent(fname, flen))
1302                 return nfserr_exist;
1303 
1304         err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
1305         if (err)
1306                 return err;
1307 
1308         dentry = fhp->fh_dentry;
1309 
1310         host_err = fh_want_write(fhp);
1311         if (host_err)
1312                 return nfserrno(host_err);
1313 
1314         fh_lock_nested(fhp, I_MUTEX_PARENT);
1315         dchild = lookup_one_len(fname, dentry, flen);
1316         host_err = PTR_ERR(dchild);
1317         if (IS_ERR(dchild))
1318                 return nfserrno(host_err);
1319         err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1320         /*
1321          * We unconditionally drop our ref to dchild as fh_compose will have
1322          * already grabbed its own ref for it.
1323          */
1324         dput(dchild);
1325         if (err)
1326                 return err;
1327         return nfsd_create_locked(rqstp, fhp, fname, flen, iap, type,
1328                                         rdev, resfhp);
1329 }
1330 
1331 #ifdef CONFIG_NFSD_V3
1332 
1333 /*
1334  * NFSv3 and NFSv4 version of nfsd_create
1335  */
1336 __be32
1337 do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
1338                 char *fname, int flen, struct iattr *iap,
1339                 struct svc_fh *resfhp, int createmode, u32 *verifier,
1340                 bool *truncp, bool *created)
1341 {
1342         struct dentry   *dentry, *dchild = NULL;
1343         struct inode    *dirp;
1344         __be32          err;
1345         int             host_err;
1346         __u32           v_mtime=0, v_atime=0;
1347 
1348         err = nfserr_perm;
1349         if (!flen)
1350                 goto out;
1351         err = nfserr_exist;
1352         if (isdotent(fname, flen))
1353                 goto out;
1354         if (!(iap->ia_valid & ATTR_MODE))
1355                 iap->ia_mode = 0;
1356         err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
1357         if (err)
1358                 goto out;
1359 
1360         dentry = fhp->fh_dentry;
1361         dirp = d_inode(dentry);
1362 
1363         host_err = fh_want_write(fhp);
1364         if (host_err)
1365                 goto out_nfserr;
1366 
1367         fh_lock_nested(fhp, I_MUTEX_PARENT);
1368 
1369         /*
1370          * Compose the response file handle.
1371          */
1372         dchild = lookup_one_len(fname, dentry, flen);
1373         host_err = PTR_ERR(dchild);
1374         if (IS_ERR(dchild))
1375                 goto out_nfserr;
1376 
1377         /* If file doesn't exist, check for permissions to create one */
1378         if (d_really_is_negative(dchild)) {
1379                 err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1380                 if (err)
1381                         goto out;
1382         }
1383 
1384         err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
1385         if (err)
1386                 goto out;
1387 
1388         if (nfsd_create_is_exclusive(createmode)) {
1389                 /* solaris7 gets confused (bugid 4218508) if these have
1390                  * the high bit set, so just clear the high bits. If this is
1391                  * ever changed to use different attrs for storing the
1392                  * verifier, then do_open_lookup() will also need to be fixed
1393                  * accordingly.
1394                  */
1395                 v_mtime = verifier[0]&0x7fffffff;
1396                 v_atime = verifier[1]&0x7fffffff;
1397         }
1398         
1399         if (d_really_is_positive(dchild)) {
1400                 err = 0;
1401 
1402                 switch (createmode) {
1403                 case NFS3_CREATE_UNCHECKED:
1404                         if (! d_is_reg(dchild))
1405                                 goto out;
1406                         else if (truncp) {
1407                                 /* in nfsv4, we need to treat this case a little
1408                                  * differently.  we don't want to truncate the
1409                                  * file now; this would be wrong if the OPEN
1410                                  * fails for some other reason.  furthermore,
1411                                  * if the size is nonzero, we should ignore it
1412                                  * according to spec!
1413                                  */
1414                                 *truncp = (iap->ia_valid & ATTR_SIZE) && !iap->ia_size;
1415                         }
1416                         else {
1417                                 iap->ia_valid &= ATTR_SIZE;
1418                                 goto set_attr;
1419                         }
1420                         break;
1421                 case NFS3_CREATE_EXCLUSIVE:
1422                         if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1423                             && d_inode(dchild)->i_atime.tv_sec == v_atime
1424                             && d_inode(dchild)->i_size  == 0 ) {
1425                                 if (created)
1426                                         *created = 1;
1427                                 break;
1428                         }
1429                         /* fall through */
1430                 case NFS4_CREATE_EXCLUSIVE4_1:
1431                         if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
1432                             && d_inode(dchild)->i_atime.tv_sec == v_atime
1433                             && d_inode(dchild)->i_size  == 0 ) {
1434                                 if (created)
1435                                         *created = 1;
1436                                 goto set_attr;
1437                         }
1438                         /* fall through */
1439                 case NFS3_CREATE_GUARDED:
1440                         err = nfserr_exist;
1441                 }
1442                 fh_drop_write(fhp);
1443                 goto out;
1444         }
1445 
1446         host_err = vfs_create(dirp, dchild, iap->ia_mode, true);
1447         if (host_err < 0) {
1448                 fh_drop_write(fhp);
1449                 goto out_nfserr;
1450         }
1451         if (created)
1452                 *created = 1;
1453 
1454         nfsd_check_ignore_resizing(iap);
1455 
1456         if (nfsd_create_is_exclusive(createmode)) {
1457                 /* Cram the verifier into atime/mtime */
1458                 iap->ia_valid = ATTR_MTIME|ATTR_ATIME
1459                         | ATTR_MTIME_SET|ATTR_ATIME_SET;
1460                 /* XXX someone who knows this better please fix it for nsec */ 
1461                 iap->ia_mtime.tv_sec = v_mtime;
1462                 iap->ia_atime.tv_sec = v_atime;
1463                 iap->ia_mtime.tv_nsec = 0;
1464                 iap->ia_atime.tv_nsec = 0;
1465         }
1466 
1467  set_attr:
1468         err = nfsd_create_setattr(rqstp, resfhp, iap);
1469 
1470         /*
1471          * nfsd_create_setattr already committed the child
1472          * (and possibly also the parent).
1473          */
1474         if (!err)
1475                 err = nfserrno(commit_metadata(fhp));
1476 
1477         /*
1478          * Update the filehandle to get the new inode info.
1479          */
1480         if (!err)
1481                 err = fh_update(resfhp);
1482 
1483  out:
1484         fh_unlock(fhp);
1485         if (dchild && !IS_ERR(dchild))
1486                 dput(dchild);
1487         fh_drop_write(fhp);
1488         return err;
1489  
1490  out_nfserr:
1491         err = nfserrno(host_err);
1492         goto out;
1493 }
1494 #endif /* CONFIG_NFSD_V3 */
1495 
1496 /*
1497  * Read a symlink. On entry, *lenp must contain the maximum path length that
1498  * fits into the buffer. On return, it contains the true length.
1499  * N.B. After this call fhp needs an fh_put
1500  */
1501 __be32
1502 nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
1503 {
1504         __be32          err;
1505         const char *link;
1506         struct path path;
1507         DEFINE_DELAYED_CALL(done);
1508         int len;
1509 
1510         err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
1511         if (unlikely(err))
1512                 return err;
1513 
1514         path.mnt = fhp->fh_export->ex_path.mnt;
1515         path.dentry = fhp->fh_dentry;
1516 
1517         if (unlikely(!d_is_symlink(path.dentry)))
1518                 return nfserr_inval;
1519 
1520         touch_atime(&path);
1521 
1522         link = vfs_get_link(path.dentry, &done);
1523         if (IS_ERR(link))
1524                 return nfserrno(PTR_ERR(link));
1525 
1526         len = strlen(link);
1527         if (len < *lenp)
1528                 *lenp = len;
1529         memcpy(buf, link, *lenp);
1530         do_delayed_call(&done);
1531         return 0;
1532 }
1533 
1534 /*
1535  * Create a symlink and look up its inode
1536  * N.B. After this call _both_ fhp and resfhp need an fh_put
1537  */
1538 __be32
1539 nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
1540                                 char *fname, int flen,
1541                                 char *path,
1542                                 struct svc_fh *resfhp)
1543 {
1544         struct dentry   *dentry, *dnew;
1545         __be32          err, cerr;
1546         int             host_err;
1547 
1548         err = nfserr_noent;
1549         if (!flen || path[0] == '\0')
1550                 goto out;
1551         err = nfserr_exist;
1552         if (isdotent(fname, flen))
1553                 goto out;
1554 
1555         err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
1556         if (err)
1557                 goto out;
1558 
1559         host_err = fh_want_write(fhp);
1560         if (host_err)
1561                 goto out_nfserr;
1562 
1563         fh_lock(fhp);
1564         dentry = fhp->fh_dentry;
1565         dnew = lookup_one_len(fname, dentry, flen);
1566         host_err = PTR_ERR(dnew);
1567         if (IS_ERR(dnew))
1568                 goto out_nfserr;
1569 
1570         host_err = vfs_symlink(d_inode(dentry), dnew, path);
1571         err = nfserrno(host_err);
1572         if (!err)
1573                 err = nfserrno(commit_metadata(fhp));
1574         fh_unlock(fhp);
1575 
1576         fh_drop_write(fhp);
1577 
1578         cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
1579         dput(dnew);
1580         if (err==0) err = cerr;
1581 out:
1582         return err;
1583 
1584 out_nfserr:
1585         err = nfserrno(host_err);
1586         goto out;
1587 }
1588 
1589 /*
1590  * Create a hardlink
1591  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1592  */
1593 __be32
1594 nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
1595                                 char *name, int len, struct svc_fh *tfhp)
1596 {
1597         struct dentry   *ddir, *dnew, *dold;
1598         struct inode    *dirp;
1599         __be32          err;
1600         int             host_err;
1601 
1602         err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
1603         if (err)
1604                 goto out;
1605         err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
1606         if (err)
1607                 goto out;
1608         err = nfserr_isdir;
1609         if (d_is_dir(tfhp->fh_dentry))
1610                 goto out;
1611         err = nfserr_perm;
1612         if (!len)
1613                 goto out;
1614         err = nfserr_exist;
1615         if (isdotent(name, len))
1616                 goto out;
1617 
1618         host_err = fh_want_write(tfhp);
1619         if (host_err) {
1620                 err = nfserrno(host_err);
1621                 goto out;
1622         }
1623 
1624         fh_lock_nested(ffhp, I_MUTEX_PARENT);
1625         ddir = ffhp->fh_dentry;
1626         dirp = d_inode(ddir);
1627 
1628         dnew = lookup_one_len(name, ddir, len);
1629         host_err = PTR_ERR(dnew);
1630         if (IS_ERR(dnew))
1631                 goto out_nfserr;
1632 
1633         dold = tfhp->fh_dentry;
1634 
1635         err = nfserr_noent;
1636         if (d_really_is_negative(dold))
1637                 goto out_dput;
1638         host_err = vfs_link(dold, dirp, dnew, NULL);
1639         if (!host_err) {
1640                 err = nfserrno(commit_metadata(ffhp));
1641                 if (!err)
1642                         err = nfserrno(commit_metadata(tfhp));
1643         } else {
1644                 if (host_err == -EXDEV && rqstp->rq_vers == 2)
1645                         err = nfserr_acces;
1646                 else
1647                         err = nfserrno(host_err);
1648         }
1649 out_dput:
1650         dput(dnew);
1651 out_unlock:
1652         fh_unlock(ffhp);
1653         fh_drop_write(tfhp);
1654 out:
1655         return err;
1656 
1657 out_nfserr:
1658         err = nfserrno(host_err);
1659         goto out_unlock;
1660 }
1661 
1662 /*
1663  * Rename a file
1664  * N.B. After this call _both_ ffhp and tfhp need an fh_put
1665  */
1666 __be32
1667 nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
1668                             struct svc_fh *tfhp, char *tname, int tlen)
1669 {
1670         struct dentry   *fdentry, *tdentry, *odentry, *ndentry, *trap;
1671         struct inode    *fdir, *tdir;
1672         __be32          err;
1673         int             host_err;
1674 
1675         err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
1676         if (err)
1677                 goto out;
1678         err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
1679         if (err)
1680                 goto out;
1681 
1682         fdentry = ffhp->fh_dentry;
1683         fdir = d_inode(fdentry);
1684 
1685         tdentry = tfhp->fh_dentry;
1686         tdir = d_inode(tdentry);
1687 
1688         err = nfserr_perm;
1689         if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
1690                 goto out;
1691 
1692         host_err = fh_want_write(ffhp);
1693         if (host_err) {
1694                 err = nfserrno(host_err);
1695                 goto out;
1696         }
1697 
1698         /* cannot use fh_lock as we need deadlock protective ordering
1699          * so do it by hand */
1700         trap = lock_rename(tdentry, fdentry);
1701         ffhp->fh_locked = tfhp->fh_locked = true;
1702         fill_pre_wcc(ffhp);
1703         fill_pre_wcc(tfhp);
1704 
1705         odentry = lookup_one_len(fname, fdentry, flen);
1706         host_err = PTR_ERR(odentry);
1707         if (IS_ERR(odentry))
1708                 goto out_nfserr;
1709 
1710         host_err = -ENOENT;
1711         if (d_really_is_negative(odentry))
1712                 goto out_dput_old;
1713         host_err = -EINVAL;
1714         if (odentry == trap)
1715                 goto out_dput_old;
1716 
1717         ndentry = lookup_one_len(tname, tdentry, tlen);
1718         host_err = PTR_ERR(ndentry);
1719         if (IS_ERR(ndentry))
1720                 goto out_dput_old;
1721         host_err = -ENOTEMPTY;
1722         if (ndentry == trap)
1723                 goto out_dput_new;
1724 
1725         host_err = -EXDEV;
1726         if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
1727                 goto out_dput_new;
1728         if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
1729                 goto out_dput_new;
1730 
1731         host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL, 0);
1732         if (!host_err) {
1733                 host_err = commit_metadata(tfhp);
1734                 if (!host_err)
1735                         host_err = commit_metadata(ffhp);
1736         }
1737  out_dput_new:
1738         dput(ndentry);
1739  out_dput_old:
1740         dput(odentry);
1741  out_nfserr:
1742         err = nfserrno(host_err);
1743         /*
1744          * We cannot rely on fh_unlock on the two filehandles,
1745          * as that would do the wrong thing if the two directories
1746          * were the same, so again we do it by hand.
1747          */
1748         fill_post_wcc(ffhp);
1749         fill_post_wcc(tfhp);
1750         unlock_rename(tdentry, fdentry);
1751         ffhp->fh_locked = tfhp->fh_locked = false;
1752         fh_drop_write(ffhp);
1753 
1754 out:
1755         return err;
1756 }
1757 
1758 /*
1759  * Unlink a file or directory
1760  * N.B. After this call fhp needs an fh_put
1761  */
1762 __be32
1763 nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
1764                                 char *fname, int flen)
1765 {
1766         struct dentry   *dentry, *rdentry;
1767         struct inode    *dirp;
1768         __be32          err;
1769         int             host_err;
1770 
1771         err = nfserr_acces;
1772         if (!flen || isdotent(fname, flen))
1773                 goto out;
1774         err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
1775         if (err)
1776                 goto out;
1777 
1778         host_err = fh_want_write(fhp);
1779         if (host_err)
1780                 goto out_nfserr;
1781 
1782         fh_lock_nested(fhp, I_MUTEX_PARENT);
1783         dentry = fhp->fh_dentry;
1784         dirp = d_inode(dentry);
1785 
1786         rdentry = lookup_one_len(fname, dentry, flen);
1787         host_err = PTR_ERR(rdentry);
1788         if (IS_ERR(rdentry))
1789                 goto out_nfserr;
1790 
1791         if (d_really_is_negative(rdentry)) {
1792                 dput(rdentry);
1793                 err = nfserr_noent;
1794                 goto out;
1795         }
1796 
1797         if (!type)
1798                 type = d_inode(rdentry)->i_mode & S_IFMT;
1799 
1800         if (type != S_IFDIR)
1801                 host_err = vfs_unlink(dirp, rdentry, NULL);
1802         else
1803                 host_err = vfs_rmdir(dirp, rdentry);
1804         if (!host_err)
1805                 host_err = commit_metadata(fhp);
1806         dput(rdentry);
1807 
1808 out_nfserr:
1809         err = nfserrno(host_err);
1810 out:
1811         return err;
1812 }
1813 
1814 /*
1815  * We do this buffering because we must not call back into the file
1816  * system's ->lookup() method from the filldir callback. That may well
1817  * deadlock a number of file systems.
1818  *
1819  * This is based heavily on the implementation of same in XFS.
1820  */
1821 struct buffered_dirent {
1822         u64             ino;
1823         loff_t          offset;
1824         int             namlen;
1825         unsigned int    d_type;
1826         char            name[];
1827 };
1828 
1829 struct readdir_data {
1830         struct dir_context ctx;
1831         char            *dirent;
1832         size_t          used;
1833         int             full;
1834 };
1835 
1836 static int nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
1837                                  int namlen, loff_t offset, u64 ino,
1838                                  unsigned int d_type)
1839 {
1840         struct readdir_data *buf =
1841                 container_of(ctx, struct readdir_data, ctx);
1842         struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
1843         unsigned int reclen;
1844 
1845         reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
1846         if (buf->used + reclen > PAGE_SIZE) {
1847                 buf->full = 1;
1848                 return -EINVAL;
1849         }
1850 
1851         de->namlen = namlen;
1852         de->offset = offset;
1853         de->ino = ino;
1854         de->d_type = d_type;
1855         memcpy(de->name, name, namlen);
1856         buf->used += reclen;
1857 
1858         return 0;
1859 }
1860 
1861 static __be32 nfsd_buffered_readdir(struct file *file, nfsd_filldir_t func,
1862                                     struct readdir_cd *cdp, loff_t *offsetp)
1863 {
1864         struct buffered_dirent *de;
1865         int host_err;
1866         int size;
1867         loff_t offset;
1868         struct readdir_data buf = {
1869                 .ctx.actor = nfsd_buffered_filldir,
1870                 .dirent = (void *)__get_free_page(GFP_KERNEL)
1871         };
1872 
1873         if (!buf.dirent)
1874                 return nfserrno(-ENOMEM);
1875 
1876         offset = *offsetp;
1877 
1878         while (1) {
1879                 unsigned int reclen;
1880 
1881                 cdp->err = nfserr_eof; /* will be cleared on successful read */
1882                 buf.used = 0;
1883                 buf.full = 0;
1884 
1885                 host_err = iterate_dir(file, &buf.ctx);
1886                 if (buf.full)
1887                         host_err = 0;
1888 
1889                 if (host_err < 0)
1890                         break;
1891 
1892                 size = buf.used;
1893 
1894                 if (!size)
1895                         break;
1896 
1897                 de = (struct buffered_dirent *)buf.dirent;
1898                 while (size > 0) {
1899                         offset = de->offset;
1900 
1901                         if (func(cdp, de->name, de->namlen, de->offset,
1902                                  de->ino, de->d_type))
1903                                 break;
1904 
1905                         if (cdp->err != nfs_ok)
1906                                 break;
1907 
1908                         reclen = ALIGN(sizeof(*de) + de->namlen,
1909                                        sizeof(u64));
1910                         size -= reclen;
1911                         de = (struct buffered_dirent *)((char *)de + reclen);
1912                 }
1913                 if (size > 0) /* We bailed out early */
1914                         break;
1915 
1916                 offset = vfs_llseek(file, 0, SEEK_CUR);
1917         }
1918 
1919         free_page((unsigned long)(buf.dirent));
1920 
1921         if (host_err)
1922                 return nfserrno(host_err);
1923 
1924         *offsetp = offset;
1925         return cdp->err;
1926 }
1927 
1928 /*
1929  * Read entries from a directory.
1930  * The  NFSv3/4 verifier we ignore for now.
1931  */
1932 __be32
1933 nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp, 
1934              struct readdir_cd *cdp, nfsd_filldir_t func)
1935 {
1936         __be32          err;
1937         struct file     *file;
1938         loff_t          offset = *offsetp;
1939         int             may_flags = NFSD_MAY_READ;
1940 
1941         /* NFSv2 only supports 32 bit cookies */
1942         if (rqstp->rq_vers > 2)
1943                 may_flags |= NFSD_MAY_64BIT_COOKIE;
1944 
1945         err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
1946         if (err)
1947                 goto out;
1948 
1949         offset = vfs_llseek(file, offset, SEEK_SET);
1950         if (offset < 0) {
1951                 err = nfserrno((int)offset);
1952                 goto out_close;
1953         }
1954 
1955         err = nfsd_buffered_readdir(file, func, cdp, offsetp);
1956 
1957         if (err == nfserr_eof || err == nfserr_toosmall)
1958                 err = nfs_ok; /* can still be found in ->err */
1959 out_close:
1960         fput(file);
1961 out:
1962         return err;
1963 }
1964 
1965 /*
1966  * Get file system stats
1967  * N.B. After this call fhp needs an fh_put
1968  */
1969 __be32
1970 nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
1971 {
1972         __be32 err;
1973 
1974         err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
1975         if (!err) {
1976                 struct path path = {
1977                         .mnt    = fhp->fh_export->ex_path.mnt,
1978                         .dentry = fhp->fh_dentry,
1979                 };
1980                 if (vfs_statfs(&path, stat))
1981                         err = nfserr_io;
1982         }
1983         return err;
1984 }
1985 
1986 static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
1987 {
1988         return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
1989 }
1990 
1991 /*
1992  * Check for a user's access permissions to this inode.
1993  */
1994 __be32
1995 nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
1996                                         struct dentry *dentry, int acc)
1997 {
1998         struct inode    *inode = d_inode(dentry);
1999         int             err;
2000 
2001         if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
2002                 return 0;
2003 #if 0
2004         dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
2005                 acc,
2006                 (acc & NFSD_MAY_READ)?  " read"  : "",
2007                 (acc & NFSD_MAY_WRITE)? " write" : "",
2008                 (acc & NFSD_MAY_EXEC)?  " exec"  : "",
2009                 (acc & NFSD_MAY_SATTR)? " sattr" : "",
2010                 (acc & NFSD_MAY_TRUNC)? " trunc" : "",
2011                 (acc & NFSD_MAY_LOCK)?  " lock"  : "",
2012                 (acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
2013                 inode->i_mode,
2014                 IS_IMMUTABLE(inode)?    " immut" : "",
2015                 IS_APPEND(inode)?       " append" : "",
2016                 __mnt_is_readonly(exp->ex_path.mnt)?    " ro" : "");
2017         dprintk("      owner %d/%d user %d/%d\n",
2018                 inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
2019 #endif
2020 
2021         /* Normally we reject any write/sattr etc access on a read-only file
2022          * system.  But if it is IRIX doing check on write-access for a 
2023          * device special file, we ignore rofs.
2024          */
2025         if (!(acc & NFSD_MAY_LOCAL_ACCESS))
2026                 if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
2027                         if (exp_rdonly(rqstp, exp) ||
2028                             __mnt_is_readonly(exp->ex_path.mnt))
2029                                 return nfserr_rofs;
2030                         if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
2031                                 return nfserr_perm;
2032                 }
2033         if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
2034                 return nfserr_perm;
2035 
2036         if (acc & NFSD_MAY_LOCK) {
2037                 /* If we cannot rely on authentication in NLM requests,
2038                  * just allow locks, otherwise require read permission, or
2039                  * ownership
2040                  */
2041                 if (exp->ex_flags & NFSEXP_NOAUTHNLM)
2042                         return 0;
2043                 else
2044                         acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
2045         }
2046         /*
2047          * The file owner always gets access permission for accesses that
2048          * would normally be checked at open time. This is to make
2049          * file access work even when the client has done a fchmod(fd, 0).
2050          *
2051          * However, `cp foo bar' should fail nevertheless when bar is
2052          * readonly. A sensible way to do this might be to reject all
2053          * attempts to truncate a read-only file, because a creat() call
2054          * always implies file truncation.
2055          * ... but this isn't really fair.  A process may reasonably call
2056          * ftruncate on an open file descriptor on a file with perm 000.
2057          * We must trust the client to do permission checking - using "ACCESS"
2058          * with NFSv3.
2059          */
2060         if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
2061             uid_eq(inode->i_uid, current_fsuid()))
2062                 return 0;
2063 
2064         /* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
2065         err = inode_permission(inode, acc & (MAY_READ|MAY_WRITE|MAY_EXEC));
2066 
2067         /* Allow read access to binaries even when mode 111 */
2068         if (err == -EACCES && S_ISREG(inode->i_mode) &&
2069              (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
2070               acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
2071                 err = inode_permission(inode, MAY_EXEC);
2072 
2073         return err? nfserrno(err) : 0;
2074 }
2075 
2076 void
2077 nfsd_racache_shutdown(void)
2078 {
2079         struct raparms *raparm, *last_raparm;
2080         unsigned int i;
2081 
2082         dprintk("nfsd: freeing readahead buffers.\n");
2083 
2084         for (i = 0; i < RAPARM_HASH_SIZE; i++) {
2085                 raparm = raparm_hash[i].pb_head;
2086                 while(raparm) {
2087                         last_raparm = raparm;
2088                         raparm = raparm->p_next;
2089                         kfree(last_raparm);
2090                 }
2091                 raparm_hash[i].pb_head = NULL;
2092         }
2093 }
2094 /*
2095  * Initialize readahead param cache
2096  */
2097 int
2098 nfsd_racache_init(int cache_size)
2099 {
2100         int     i;
2101         int     j = 0;
2102         int     nperbucket;
2103         struct raparms **raparm = NULL;
2104 
2105 
2106         if (raparm_hash[0].pb_head)
2107                 return 0;
2108         nperbucket = DIV_ROUND_UP(cache_size, RAPARM_HASH_SIZE);
2109         nperbucket = max(2, nperbucket);
2110         cache_size = nperbucket * RAPARM_HASH_SIZE;
2111 
2112         dprintk("nfsd: allocating %d readahead buffers.\n", cache_size);
2113 
2114         for (i = 0; i < RAPARM_HASH_SIZE; i++) {
2115                 spin_lock_init(&raparm_hash[i].pb_lock);
2116 
2117                 raparm = &raparm_hash[i].pb_head;
2118                 for (j = 0; j < nperbucket; j++) {
2119                         *raparm = kzalloc(sizeof(struct raparms), GFP_KERNEL);
2120                         if (!*raparm)
2121                                 goto out_nomem;
2122                         raparm = &(*raparm)->p_next;
2123                 }
2124                 *raparm = NULL;
2125         }
2126 
2127         nfsdstats.ra_size = cache_size;
2128         return 0;
2129 
2130 out_nomem:
2131         dprintk("nfsd: kmalloc failed, freeing readahead buffers\n");
2132         nfsd_racache_shutdown();
2133         return -ENOMEM;
2134 }
2135 

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