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

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