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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * File operations used by nfsd. Some of these have been ripped from
  * other parts of the kernel because they weren't exported, others
  * are partial duplicates with added or changed functionality.
  *
  * Note that several functions dget() the dentry upon which they want
  * to act, most notably those that create directory entries. Response
  * dentry's are dput()'d if necessary in the release callback.
  * So if you notice code paths that apparently fail to dput() the
  * dentry, don't worry--they have been taken care of.
  *
  * Copyright (C) 1995-1999 Olaf Kirch <okir@monad.swb.de>
  * Zerocpy NFS support (C) 2002 Hirokazu Takahashi <taka@valinux.co.jp>
  */
 
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/splice.h>
 #include <linux/falloc.h>
 #include <linux/fcntl.h>
 #include <linux/namei.h>
 #include <linux/delay.h>
 #include <linux/fsnotify.h>
 #include <linux/posix_acl_xattr.h>
 #include <linux/xattr.h>
 #include <linux/jhash.h>
 #include <linux/ima.h>
 #include <linux/pagemap.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/exportfs.h>
 #include <linux/writeback.h>
 #include <linux/security.h>
 
 #include "xdr3.h"
 
 #ifdef CONFIG_NFSD_V4
 #include "../internal.h"
 #include "acl.h"
 #include "idmap.h"
 #include "xdr4.h"
 #endif /* CONFIG_NFSD_V4 */
 
 #include "nfsd.h"
 #include "vfs.h"
 #include "filecache.h"
 #include "trace.h"
 
 #define NFSDDBG_FACILITY        NFSDDBG_FILEOP
 
 /* 
  * Called from nfsd_lookup and encode_dirent. Check if we have crossed 
  * a mount point.
  * Returns -EAGAIN or -ETIMEDOUT leaving *dpp and *expp unchanged,
  *  or nfs_ok having possibly changed *dpp and *expp
  */
 int
 nfsd_cross_mnt(struct svc_rqst *rqstp, struct dentry **dpp, 
                 struct svc_export **expp)
 {
     struct svc_export *exp = *expp, *exp2 = NULL;
     struct dentry *dentry = *dpp;
     struct path path = {.mnt = mntget(exp->ex_path.mnt),
                 .dentry = dget(dentry)};
     int err = 0;
 
     err = follow_down(&path);
     if (err < 0)
         goto out;
     if (path.mnt == exp->ex_path.mnt && path.dentry == dentry &&
         nfsd_mountpoint(dentry, exp) == 2) {
         /* This is only a mountpoint in some other namespace */
         path_put(&path);
         goto out;
     }
 
     exp2 = rqst_exp_get_by_name(rqstp, &path);
     if (IS_ERR(exp2)) {
         err = PTR_ERR(exp2);
         /*
          * We normally allow NFS clients to continue
          * "underneath" a mountpoint that is not exported.
          * The exception is V4ROOT, where no traversal is ever
          * allowed without an explicit export of the new
          * directory.
          */
         if (err == -ENOENT && !(exp->ex_flags & NFSEXP_V4ROOT))
             err = 0;
         path_put(&path);
         goto out;
     }
     if (nfsd_v4client(rqstp) ||
         (exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
         /* successfully crossed mount point */
         /*
          * This is subtle: path.dentry is *not* on path.mnt
          * at this point.  The only reason we are safe is that
          * original mnt is pinned down by exp, so we should
          * put path *before* putting exp
          */
         *dpp = path.dentry;
         path.dentry = dentry;
         *expp = exp2;
         exp2 = exp;
     }
     path_put(&path);
     exp_put(exp2);
 out:
     return err;
 }
 
 static void follow_to_parent(struct path *path)
 {
     struct dentry *dp;
 
     while (path->dentry == path->mnt->mnt_root && follow_up(path))
         ;
     dp = dget_parent(path->dentry);
     dput(path->dentry);
     path->dentry = dp;
 }
 
 static int nfsd_lookup_parent(struct svc_rqst *rqstp, struct dentry *dparent, struct svc_export **exp, struct dentry **dentryp)
 {
     struct svc_export *exp2;
     struct path path = {.mnt = mntget((*exp)->ex_path.mnt),
                 .dentry = dget(dparent)};
 
     follow_to_parent(&path);
 
     exp2 = rqst_exp_parent(rqstp, &path);
     if (PTR_ERR(exp2) == -ENOENT) {
         *dentryp = dget(dparent);
     } else if (IS_ERR(exp2)) {
         path_put(&path);
         return PTR_ERR(exp2);
     } else {
         *dentryp = dget(path.dentry);
         exp_put(*exp);
         *exp = exp2;
     }
     path_put(&path);
     return 0;
 }
 
 /*
  * For nfsd purposes, we treat V4ROOT exports as though there was an
  * export at *every* directory.
  * We return:
  * '1' if this dentry *must* be an export point,
  * '2' if it might be, if there is really a mount here, and
  * '0' if there is no chance of an export point here.
  */
 int nfsd_mountpoint(struct dentry *dentry, struct svc_export *exp)
 {
     if (!d_inode(dentry))
         return 0;
     if (exp->ex_flags & NFSEXP_V4ROOT)
         return 1;
     if (nfsd4_is_junction(dentry))
         return 1;
     if (d_mountpoint(dentry))
         /*
          * Might only be a mountpoint in a different namespace,
          * but we need to check.
          */
         return 2;
     return 0;
 }
 
 __be32
 nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
            const char *name, unsigned int len,
            struct svc_export **exp_ret, struct dentry **dentry_ret)
 {
     struct svc_export   *exp;
     struct dentry       *dparent;
     struct dentry       *dentry;
     int         host_err;
 
     dprintk("nfsd: nfsd_lookup(fh %s, %.*s)\n", SVCFH_fmt(fhp), len,name);
 
     dparent = fhp->fh_dentry;
     exp = exp_get(fhp->fh_export);
 
     /* Lookup the name, but don't follow links */
     if (isdotent(name, len)) {
         if (len==1)
             dentry = dget(dparent);
         else if (dparent != exp->ex_path.dentry)
             dentry = dget_parent(dparent);
         else if (!EX_NOHIDE(exp) && !nfsd_v4client(rqstp))
             dentry = dget(dparent); /* .. == . just like at / */
         else {
             /* checking mountpoint crossing is very different when stepping up */
             host_err = nfsd_lookup_parent(rqstp, dparent, &exp, &dentry);
             if (host_err)
                 goto out_nfserr;
         }
     } else {
         dentry = lookup_one_len_unlocked(name, dparent, len);
         host_err = PTR_ERR(dentry);
         if (IS_ERR(dentry))
             goto out_nfserr;
         if (nfsd_mountpoint(dentry, exp)) {
             host_err = nfsd_cross_mnt(rqstp, &dentry, &exp);
             if (host_err) {
                 dput(dentry);
                 goto out_nfserr;
             }
         }
     }
     *dentry_ret = dentry;
     *exp_ret = exp;
     return 0;
 
 out_nfserr:
     exp_put(exp);
     return nfserrno(host_err);
 }
 
 /**
  * nfsd_lookup - look up a single path component for nfsd
  *
  * @rqstp:   the request context
  * @fhp:     the file handle of the directory
  * @name:    the component name, or %NULL to look up parent
  * @len:     length of name to examine
  * @resfh:   pointer to pre-initialised filehandle to hold result.
  *
  * Look up one component of a pathname.
  * N.B. After this call _both_ fhp and resfh need an fh_put
  *
  * If the lookup would cross a mountpoint, and the mounted filesystem
  * is exported to the client with NFSEXP_NOHIDE, then the lookup is
  * accepted as it stands and the mounted directory is
  * returned. Otherwise the covered directory is returned.
  * NOTE: this mountpoint crossing is not supported properly by all
  *   clients and is explicitly disallowed for NFSv3
  *
  */
 __be32
 nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
         unsigned int len, struct svc_fh *resfh)
 {
     struct svc_export   *exp;
     struct dentry       *dentry;
     __be32 err;
 
     err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
     if (err)
         return err;
     err = nfsd_lookup_dentry(rqstp, fhp, name, len, &exp, &dentry);
     if (err)
         return err;
     err = check_nfsd_access(exp, rqstp);
     if (err)
         goto out;
     /*
      * Note: we compose the file handle now, but as the
      * dentry may be negative, it may need to be updated.
      */
     err = fh_compose(resfh, exp, dentry, fhp);
     if (!err && d_really_is_negative(dentry))
         err = nfserr_noent;
 out:
     dput(dentry);
     exp_put(exp);
     return err;
 }
 
 /*
  * Commit metadata changes to stable storage.
  */
 static int
 commit_inode_metadata(struct inode *inode)
 {
     const struct export_operations *export_ops = inode->i_sb->s_export_op;
 
     if (export_ops->commit_metadata)
         return export_ops->commit_metadata(inode);
     return sync_inode_metadata(inode, 1);
 }
 
 static int
 commit_metadata(struct svc_fh *fhp)
 {
     struct inode *inode = d_inode(fhp->fh_dentry);
 
     if (!EX_ISSYNC(fhp->fh_export))
         return 0;
     return commit_inode_metadata(inode);
 }
 
 /*
  * Go over the attributes and take care of the small differences between
  * NFS semantics and what Linux expects.
  */
 static void
 nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
 {
     /* Ignore mode updates on symlinks */
     if (S_ISLNK(inode->i_mode))
         iap->ia_valid &= ~ATTR_MODE;
 
     /* sanitize the mode change */
     if (iap->ia_valid & ATTR_MODE) {
         iap->ia_mode &= S_IALLUGO;
         iap->ia_mode |= (inode->i_mode & ~S_IALLUGO);
     }
 
     /* Revoke setuid/setgid on chown */
     if (!S_ISDIR(inode->i_mode) &&
         ((iap->ia_valid & ATTR_UID) || (iap->ia_valid & ATTR_GID))) {
         iap->ia_valid |= ATTR_KILL_PRIV;
         if (iap->ia_valid & ATTR_MODE) {
             /* we're setting mode too, just clear the s*id bits */
             iap->ia_mode &= ~S_ISUID;
             if (iap->ia_mode & S_IXGRP)
                 iap->ia_mode &= ~S_ISGID;
         } else {
             /* set ATTR_KILL_* bits and let VFS handle it */
             iap->ia_valid |= (ATTR_KILL_SUID | ATTR_KILL_SGID);
         }
     }
 }
 
 static __be32
 nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
         struct iattr *iap)
 {
     struct inode *inode = d_inode(fhp->fh_dentry);
 
     if (iap->ia_size < inode->i_size) {
         __be32 err;
 
         err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
                 NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
         if (err)
             return err;
     }
     return nfserrno(get_write_access(inode));
 }
 
 /*
  * Set various file attributes.  After this call fhp needs an fh_put.
  */
 __be32
 nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
          struct nfsd_attrs *attr,
          int check_guard, time64_t guardtime)
 {
     struct dentry   *dentry;
     struct inode    *inode;
     struct iattr    *iap = attr->na_iattr;
     int     accmode = NFSD_MAY_SATTR;
     umode_t     ftype = 0;
     __be32      err;
     int     host_err = 0;
     bool        get_write_count;
     bool        size_change = (iap->ia_valid & ATTR_SIZE);
 
     if (iap->ia_valid & ATTR_SIZE) {
         accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
         ftype = S_IFREG;
     }
 
     /*
      * If utimes(2) and friends are called with times not NULL, we should
      * not set NFSD_MAY_WRITE bit. Otherwise fh_verify->nfsd_permission
      * will return EACCES, when the caller's effective UID does not match
      * the owner of the file, and the caller is not privileged. In this
      * situation, we should return EPERM(notify_change will return this).
      */
     if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME)) {
         accmode |= NFSD_MAY_OWNER_OVERRIDE;
         if (!(iap->ia_valid & (ATTR_ATIME_SET | ATTR_MTIME_SET)))
             accmode |= NFSD_MAY_WRITE;
     }
 
     /* Callers that do fh_verify should do the fh_want_write: */
     get_write_count = !fhp->fh_dentry;
 
     /* Get inode */
     err = fh_verify(rqstp, fhp, ftype, accmode);
     if (err)
         return err;
     if (get_write_count) {
         host_err = fh_want_write(fhp);
         if (host_err)
             goto out;
     }
 
     dentry = fhp->fh_dentry;
     inode = d_inode(dentry);
 
     nfsd_sanitize_attrs(inode, iap);
 
     if (check_guard && guardtime != inode->i_ctime.tv_sec)
         return nfserr_notsync;
 
     /*
      * The size case is special, it changes the file in addition to the
      * attributes, and file systems don't expect it to be mixed with
      * "random" attribute changes.  We thus split out the size change
      * into a separate call to ->setattr, and do the rest as a separate
      * setattr call.
      */
     if (size_change) {
         err = nfsd_get_write_access(rqstp, fhp, iap);
         if (err)
             return err;
     }
 
     inode_lock(inode);
     if (size_change) {
         /*
          * RFC5661, Section 18.30.4:
          *   Changing the size of a file with SETATTR indirectly
          *   changes the time_modify and change attributes.
          *
          * (and similar for the older RFCs)
          */
         struct iattr size_attr = {
             .ia_valid   = ATTR_SIZE | ATTR_CTIME | ATTR_MTIME,
             .ia_size    = iap->ia_size,
         };
 
         host_err = -EFBIG;
         if (iap->ia_size < 0)
             goto out_unlock;
 
         host_err = notify_change(&init_user_ns, dentry, &size_attr, NULL);
         if (host_err)
             goto out_unlock;
         iap->ia_valid &= ~ATTR_SIZE;
 
         /*
          * Avoid the additional setattr call below if the only other
          * attribute that the client sends is the mtime, as we update
          * it as part of the size change above.
          */
         if ((iap->ia_valid & ~ATTR_MTIME) == 0)
             goto out_unlock;
     }
 
     if (iap->ia_valid) {
         iap->ia_valid |= ATTR_CTIME;
         host_err = notify_change(&init_user_ns, dentry, iap, NULL);
     }
 
 out_unlock:
     if (attr->na_seclabel && attr->na_seclabel->len)
         attr->na_labelerr = security_inode_setsecctx(dentry,
             attr->na_seclabel->data, attr->na_seclabel->len);
     if (IS_ENABLED(CONFIG_FS_POSIX_ACL) && attr->na_pacl)
         attr->na_aclerr = set_posix_acl(&init_user_ns,
                         inode, ACL_TYPE_ACCESS,
                         attr->na_pacl);
     if (IS_ENABLED(CONFIG_FS_POSIX_ACL) &&
         !attr->na_aclerr && attr->na_dpacl && S_ISDIR(inode->i_mode))
         attr->na_aclerr = set_posix_acl(&init_user_ns,
                         inode, ACL_TYPE_DEFAULT,
                         attr->na_dpacl);
     inode_unlock(inode);
     if (size_change)
         put_write_access(inode);
 out:
     if (!host_err)
         host_err = commit_metadata(fhp);
     return nfserrno(host_err);
 }
 
 #if defined(CONFIG_NFSD_V4)
 /*
  * NFS junction information is stored in an extended attribute.
  */
 #define NFSD_JUNCTION_XATTR_NAME    XATTR_TRUSTED_PREFIX "junction.nfs"
 
 /**
  * nfsd4_is_junction - Test if an object could be an NFS junction
  *
  * @dentry: object to test
  *
  * Returns 1 if "dentry" appears to contain NFS junction information.
  * Otherwise 0 is returned.
  */
 int nfsd4_is_junction(struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
 
     if (inode == NULL)
         return 0;
     if (inode->i_mode & S_IXUGO)
         return 0;
     if (!(inode->i_mode & S_ISVTX))
         return 0;
     if (vfs_getxattr(&init_user_ns, dentry, NFSD_JUNCTION_XATTR_NAME,
              NULL, 0) <= 0)
         return 0;
     return 1;
 }
 
 static struct nfsd4_compound_state *nfsd4_get_cstate(struct svc_rqst *rqstp)
 {
     return &((struct nfsd4_compoundres *)rqstp->rq_resp)->cstate;
 }
 
 __be32 nfsd4_clone_file_range(struct svc_rqst *rqstp,
         struct nfsd_file *nf_src, u64 src_pos,
         struct nfsd_file *nf_dst, u64 dst_pos,
         u64 count, bool sync)
 {
     struct file *src = nf_src->nf_file;
     struct file *dst = nf_dst->nf_file;
     errseq_t since;
     loff_t cloned;
     __be32 ret = 0;
 
     since = READ_ONCE(dst->f_wb_err);
     cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
     if (cloned < 0) {
         ret = nfserrno(cloned);
         goto out_err;
     }
     if (count && cloned != count) {
         ret = nfserrno(-EINVAL);
         goto out_err;
     }
     if (sync) {
         loff_t dst_end = count ? dst_pos + count - 1 : LLONG_MAX;
         int status = vfs_fsync_range(dst, dst_pos, dst_end, 0);
 
         if (!status)
             status = filemap_check_wb_err(dst->f_mapping, since);
         if (!status)
             status = commit_inode_metadata(file_inode(src));
         if (status < 0) {
             struct nfsd_net *nn = net_generic(nf_dst->nf_net,
                               nfsd_net_id);
 
             trace_nfsd_clone_file_range_err(rqstp,
                     &nfsd4_get_cstate(rqstp)->save_fh,
                     src_pos,
                     &nfsd4_get_cstate(rqstp)->current_fh,
                     dst_pos,
                     count, status);
             nfsd_reset_write_verifier(nn);
             trace_nfsd_writeverf_reset(nn, rqstp, status);
             ret = nfserrno(status);
         }
     }
 out_err:
     return ret;
 }
 
 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
                  u64 dst_pos, u64 count)
 {
     ssize_t ret;
 
     /*
      * Limit copy to 4MB to prevent indefinitely blocking an nfsd
      * thread and client rpc slot.  The choice of 4MB is somewhat
      * arbitrary.  We might instead base this on r/wsize, or make it
      * tunable, or use a time instead of a byte limit, or implement
      * asynchronous copy.  In theory a client could also recognize a
      * limit like this and pipeline multiple COPY requests.
      */
     count = min_t(u64, count, 1 << 22);
     ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0);
 
     if (ret == -EOPNOTSUPP || ret == -EXDEV)
         ret = generic_copy_file_range(src, src_pos, dst, dst_pos,
                           count, 0);
     return ret;
 }
 
 __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp,
                struct file *file, loff_t offset, loff_t len,
                int flags)
 {
     int error;
 
     if (!S_ISREG(file_inode(file)->i_mode))
         return nfserr_inval;
 
     error = vfs_fallocate(file, flags, offset, len);
     if (!error)
         error = commit_metadata(fhp);
 
     return nfserrno(error);
 }
 #endif /* defined(CONFIG_NFSD_V4) */
 
 /*
  * Check server access rights to a file system object
  */
 struct accessmap {
     u32     access;
     int     how;
 };
 static struct accessmap nfs3_regaccess[] = {
     {   NFS3_ACCESS_READ,   NFSD_MAY_READ           },
     {   NFS3_ACCESS_EXECUTE,    NFSD_MAY_EXEC           },
     {   NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_TRUNC   },
     {   NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE          },
 
 #ifdef CONFIG_NFSD_V4
     {   NFS4_ACCESS_XAREAD, NFSD_MAY_READ           },
     {   NFS4_ACCESS_XAWRITE,    NFSD_MAY_WRITE          },
     {   NFS4_ACCESS_XALIST, NFSD_MAY_READ           },
 #endif
 
     {   0,          0               }
 };
 
 static struct accessmap nfs3_diraccess[] = {
     {   NFS3_ACCESS_READ,   NFSD_MAY_READ           },
     {   NFS3_ACCESS_LOOKUP, NFSD_MAY_EXEC           },
     {   NFS3_ACCESS_MODIFY, NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC},
     {   NFS3_ACCESS_EXTEND, NFSD_MAY_EXEC|NFSD_MAY_WRITE    },
     {   NFS3_ACCESS_DELETE, NFSD_MAY_REMOVE         },
 
 #ifdef CONFIG_NFSD_V4
     {   NFS4_ACCESS_XAREAD, NFSD_MAY_READ           },
     {   NFS4_ACCESS_XAWRITE,    NFSD_MAY_WRITE          },
     {   NFS4_ACCESS_XALIST, NFSD_MAY_READ           },
 #endif
 
     {   0,          0               }
 };
 
 static struct accessmap nfs3_anyaccess[] = {
     /* Some clients - Solaris 2.6 at least, make an access call
      * to the server to check for access for things like /dev/null
      * (which really, the server doesn't care about).  So
      * We provide simple access checking for them, looking
      * mainly at mode bits, and we make sure to ignore read-only
      * filesystem checks
      */
     {   NFS3_ACCESS_READ,   NFSD_MAY_READ           },
     {   NFS3_ACCESS_EXECUTE,    NFSD_MAY_EXEC           },
     {   NFS3_ACCESS_MODIFY, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS    },
     {   NFS3_ACCESS_EXTEND, NFSD_MAY_WRITE|NFSD_MAY_LOCAL_ACCESS    },
 
     {   0,          0               }
 };
 
 __be32
 nfsd_access(struct svc_rqst *rqstp, struct svc_fh *fhp, u32 *access, u32 *supported)
 {
     struct accessmap    *map;
     struct svc_export   *export;
     struct dentry       *dentry;
     u32         query, result = 0, sresult = 0;
     __be32          error;
 
     error = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP);
     if (error)
         goto out;
 
     export = fhp->fh_export;
     dentry = fhp->fh_dentry;
 
     if (d_is_reg(dentry))
         map = nfs3_regaccess;
     else if (d_is_dir(dentry))
         map = nfs3_diraccess;
     else
         map = nfs3_anyaccess;
 
 
     query = *access;
     for  (; map->access; map++) {
         if (map->access & query) {
             __be32 err2;
 
             sresult |= map->access;
 
             err2 = nfsd_permission(rqstp, export, dentry, map->how);
             switch (err2) {
             case nfs_ok:
                 result |= map->access;
                 break;
                 
             /* the following error codes just mean the access was not allowed,
              * rather than an error occurred */
             case nfserr_rofs:
             case nfserr_acces:
             case nfserr_perm:
                 /* simply don't "or" in the access bit. */
                 break;
             default:
                 error = err2;
                 goto out;
             }
         }
     }
     *access = result;
     if (supported)
         *supported = sresult;
 
  out:
     return error;
 }
 
 int nfsd_open_break_lease(struct inode *inode, int access)
 {
     unsigned int mode;
 
     if (access & NFSD_MAY_NOT_BREAK_LEASE)
         return 0;
     mode = (access & NFSD_MAY_WRITE) ? O_WRONLY : O_RDONLY;
     return break_lease(inode, mode | O_NONBLOCK);
 }
 
 /*
  * Open an existing file or directory.
  * The may_flags argument indicates the type of open (read/write/lock)
  * and additional flags.
  * N.B. After this call fhp needs an fh_put
  */
 static __be32
 __nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
             int may_flags, struct file **filp)
 {
     struct path path;
     struct inode    *inode;
     struct file *file;
     int     flags = O_RDONLY|O_LARGEFILE;
     __be32      err;
     int     host_err = 0;
 
     path.mnt = fhp->fh_export->ex_path.mnt;
     path.dentry = fhp->fh_dentry;
     inode = d_inode(path.dentry);
 
     err = nfserr_perm;
     if (IS_APPEND(inode) && (may_flags & NFSD_MAY_WRITE))
         goto out;
 
     if (!inode->i_fop)
         goto out;
 
     host_err = nfsd_open_break_lease(inode, may_flags);
     if (host_err) /* NOMEM or WOULDBLOCK */
         goto out_nfserr;
 
     if (may_flags & NFSD_MAY_WRITE) {
         if (may_flags & NFSD_MAY_READ)
             flags = O_RDWR|O_LARGEFILE;
         else
             flags = O_WRONLY|O_LARGEFILE;
     }
 
     file = dentry_open(&path, flags, current_cred());
     if (IS_ERR(file)) {
         host_err = PTR_ERR(file);
         goto out_nfserr;
     }
 
     host_err = ima_file_check(file, may_flags);
     if (host_err) {
         fput(file);
         goto out_nfserr;
     }
 
     if (may_flags & NFSD_MAY_64BIT_COOKIE)
         file->f_mode |= FMODE_64BITHASH;
     else
         file->f_mode |= FMODE_32BITHASH;
 
     *filp = file;
 out_nfserr:
     err = nfserrno(host_err);
 out:
     return err;
 }
 
 __be32
 nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type,
         int may_flags, struct file **filp)
 {
     __be32 err;
     bool retried = false;
 
     validate_process_creds();
     /*
      * If we get here, then the client has already done an "open",
      * and (hopefully) checked permission - so allow OWNER_OVERRIDE
      * in case a chmod has now revoked permission.
      *
      * Arguably we should also allow the owner override for
      * directories, but we never have and it doesn't seem to have
      * caused anyone a problem.  If we were to change this, note
      * also that our filldir callbacks would need a variant of
      * lookup_one_len that doesn't check permissions.
      */
     if (type == S_IFREG)
         may_flags |= NFSD_MAY_OWNER_OVERRIDE;
 retry:
     err = fh_verify(rqstp, fhp, type, may_flags);
     if (!err) {
         err = __nfsd_open(rqstp, fhp, type, may_flags, filp);
         if (err == nfserr_stale && !retried) {
             retried = true;
             fh_put(fhp);
             goto retry;
         }
     }
     validate_process_creds();
     return err;
 }
 
 /**
  * nfsd_open_verified - Open a regular file for the filecache
  * @rqstp: RPC request
  * @fhp: NFS filehandle of the file to open
  * @may_flags: internal permission flags
  * @filp: OUT: open "struct file *"
  *
  * Returns an nfsstat value in network byte order.
  */
 __be32
 nfsd_open_verified(struct svc_rqst *rqstp, struct svc_fh *fhp, int may_flags,
            struct file **filp)
 {
     __be32 err;
 
     validate_process_creds();
     err = __nfsd_open(rqstp, fhp, S_IFREG, may_flags, filp);
     validate_process_creds();
     return err;
 }
 
 /*
  * Grab and keep cached pages associated with a file in the svc_rqst
  * so that they can be passed to the network sendmsg/sendpage routines
  * directly. They will be released after the sending has completed.
  */
 static int
 nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
           struct splice_desc *sd)
 {
     struct svc_rqst *rqstp = sd->u.data;
     struct page *page = buf->page;  // may be a compound one
     unsigned offset = buf->offset;
 
     page += offset / PAGE_SIZE;
     for (int i = sd->len; i > 0; i -= PAGE_SIZE)
         svc_rqst_replace_page(rqstp, page++);
     if (rqstp->rq_res.page_len == 0)    // first call
         rqstp->rq_res.page_base = offset % PAGE_SIZE;
     rqstp->rq_res.page_len += sd->len;
     return sd->len;
 }
 
 static int nfsd_direct_splice_actor(struct pipe_inode_info *pipe,
                     struct splice_desc *sd)
 {
     return __splice_from_pipe(pipe, sd, nfsd_splice_actor);
 }
 
 static u32 nfsd_eof_on_read(struct file *file, loff_t offset, ssize_t len,
         size_t expected)
 {
     if (expected != 0 && len == 0)
         return 1;
     if (offset+len >= i_size_read(file_inode(file)))
         return 1;
     return 0;
 }
 
 static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
                    struct file *file, loff_t offset,
                    unsigned long *count, u32 *eof, ssize_t host_err)
 {
     if (host_err >= 0) {
         nfsd_stats_io_read_add(fhp->fh_export, host_err);
         *eof = nfsd_eof_on_read(file, offset, host_err, *count);
         *count = host_err;
         fsnotify_access(file);
         trace_nfsd_read_io_done(rqstp, fhp, offset, *count);
         return 0;
     } else {
         trace_nfsd_read_err(rqstp, fhp, offset, host_err);
         return nfserrno(host_err);
     }
 }
 
 __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
             struct file *file, loff_t offset, unsigned long *count,
             u32 *eof)
 {
     struct splice_desc sd = {
         .len        = 0,
         .total_len  = *count,
         .pos        = offset,
         .u.data     = rqstp,
     };
     ssize_t host_err;
 
     trace_nfsd_read_splice(rqstp, fhp, offset, *count);
     rqstp->rq_next_page = rqstp->rq_respages + 1;
     host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);
     return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
 }
 
 __be32 nfsd_readv(struct svc_rqst *rqstp, struct svc_fh *fhp,
           struct file *file, loff_t offset,
           struct kvec *vec, int vlen, unsigned long *count,
           u32 *eof)
 {
     struct iov_iter iter;
     loff_t ppos = offset;
     ssize_t host_err;
 
     trace_nfsd_read_vector(rqstp, fhp, offset, *count);
     iov_iter_kvec(&iter, READ, vec, vlen, *count);
     host_err = vfs_iter_read(file, &iter, &ppos, 0);
     return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);
 }
 
 /*
  * Gathered writes: If another process is currently writing to the file,
  * there's a high chance this is another nfsd (triggered by a bulk write
  * from a client's biod). Rather than syncing the file with each write
  * request, we sleep for 10 msec.
  *
  * I don't know if this roughly approximates C. Juszak's idea of
  * gathered writes, but it's a nice and simple solution (IMHO), and it
  * seems to work:-)
  *
  * Note: we do this only in the NFSv2 case, since v3 and higher have a
  * better tool (separate unstable writes and commits) for solving this
  * problem.
  */
 static int wait_for_concurrent_writes(struct file *file)
 {
     struct inode *inode = file_inode(file);
     static ino_t last_ino;
     static dev_t last_dev;
     int err = 0;
 
     if (atomic_read(&inode->i_writecount) > 1
         || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
         dprintk("nfsd: write defer %d\n", task_pid_nr(current));
         msleep(10);
         dprintk("nfsd: write resume %d\n", task_pid_nr(current));
     }
 
     if (inode->i_state & I_DIRTY) {
         dprintk("nfsd: write sync %d\n", task_pid_nr(current));
         err = vfs_fsync(file, 0);
     }
     last_ino = inode->i_ino;
     last_dev = inode->i_sb->s_dev;
     return err;
 }
 
 __be32
 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfsd_file *nf,
                 loff_t offset, struct kvec *vec, int vlen,
                 unsigned long *cnt, int stable,
                 __be32 *verf)
 {
     struct nfsd_net     *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
     struct file     *file = nf->nf_file;
     struct super_block  *sb = file_inode(file)->i_sb;
     struct svc_export   *exp;
     struct iov_iter     iter;
     errseq_t        since;
     __be32          nfserr;
     int         host_err;
     int         use_wgather;
     loff_t          pos = offset;
     unsigned long       exp_op_flags = 0;
     unsigned int        pflags = current->flags;
     rwf_t           flags = 0;
     bool            restore_flags = false;
 
     trace_nfsd_write_opened(rqstp, fhp, offset, *cnt);
 
     if (sb->s_export_op)
         exp_op_flags = sb->s_export_op->flags;
 
     if (test_bit(RQ_LOCAL, &rqstp->rq_flags) &&
         !(exp_op_flags & EXPORT_OP_REMOTE_FS)) {
         /*
          * We want throttling in balance_dirty_pages()
          * and shrink_inactive_list() to only consider
          * the backingdev we are writing to, so that nfs to
          * localhost doesn't cause nfsd to lock up due to all
          * the client's dirty pages or its congested queue.
          */
         current->flags |= PF_LOCAL_THROTTLE;
         restore_flags = true;
     }
 
     exp = fhp->fh_export;
     use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
 
     if (!EX_ISSYNC(exp))
         stable = NFS_UNSTABLE;
 
     if (stable && !use_wgather)
         flags |= RWF_SYNC;
 
     iov_iter_kvec(&iter, WRITE, vec, vlen, *cnt);
     since = READ_ONCE(file->f_wb_err);
     if (verf)
         nfsd_copy_write_verifier(verf, nn);
     host_err = vfs_iter_write(file, &iter, &pos, flags);
     if (host_err < 0) {
         nfsd_reset_write_verifier(nn);
         trace_nfsd_writeverf_reset(nn, rqstp, host_err);
         goto out_nfserr;
     }
     *cnt = host_err;
     nfsd_stats_io_write_add(exp, *cnt);
     fsnotify_modify(file);
     host_err = filemap_check_wb_err(file->f_mapping, since);
     if (host_err < 0)
         goto out_nfserr;
 
     if (stable && use_wgather) {
         host_err = wait_for_concurrent_writes(file);
         if (host_err < 0) {
             nfsd_reset_write_verifier(nn);
             trace_nfsd_writeverf_reset(nn, rqstp, host_err);
         }
     }
 
 out_nfserr:
     if (host_err >= 0) {
         trace_nfsd_write_io_done(rqstp, fhp, offset, *cnt);
         nfserr = nfs_ok;
     } else {
         trace_nfsd_write_err(rqstp, fhp, offset, host_err);
         nfserr = nfserrno(host_err);
     }
     if (restore_flags)
         current_restore_flags(pflags, PF_LOCAL_THROTTLE);
     return nfserr;
 }
 
 /*
  * Read data from a file. count must contain the requested read count
  * on entry. On return, *count contains the number of bytes actually read.
  * N.B. After this call fhp needs an fh_put
  */
 __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
     loff_t offset, struct kvec *vec, int vlen, unsigned long *count,
     u32 *eof)
 {
     struct nfsd_file    *nf;
     struct file *file;
     __be32 err;
 
     trace_nfsd_read_start(rqstp, fhp, offset, *count);
     err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
     if (err)
         return err;
 
     file = nf->nf_file;
     if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &rqstp->rq_flags))
         err = nfsd_splice_read(rqstp, fhp, file, offset, count, eof);
     else
         err = nfsd_readv(rqstp, fhp, file, offset, vec, vlen, count, eof);
 
     nfsd_file_put(nf);
 
     trace_nfsd_read_done(rqstp, fhp, offset, *count);
 
     return err;
 }
 
 /*
  * Write data to a file.
  * The stable flag requests synchronous writes.
  * N.B. After this call fhp needs an fh_put
  */
 __be32
 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
        struct kvec *vec, int vlen, unsigned long *cnt, int stable,
        __be32 *verf)
 {
     struct nfsd_file *nf;
     __be32 err;
 
     trace_nfsd_write_start(rqstp, fhp, offset, *cnt);
 
     err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_WRITE, &nf);
     if (err)
         goto out;
 
     err = nfsd_vfs_write(rqstp, fhp, nf, offset, vec,
             vlen, cnt, stable, verf);
     nfsd_file_put(nf);
 out:
     trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
     return err;
 }
 
 /**
  * nfsd_commit - Commit pending writes to stable storage
  * @rqstp: RPC request being processed
  * @fhp: NFS filehandle
  * @offset: raw offset from beginning of file
  * @count: raw count of bytes to sync
  * @verf: filled in with the server's current write verifier
  *
  * Note: we guarantee that data that lies within the range specified
  * by the 'offset' and 'count' parameters will be synced. The server
  * is permitted to sync data that lies outside this range at the
  * same time.
  *
  * Unfortunately we cannot lock the file to make sure we return full WCC
  * data to the client, as locking happens lower down in the filesystem.
  *
  * Return values:
  *   An nfsstat value in network byte order.
  */
 __be32
 nfsd_commit(struct svc_rqst *rqstp, struct svc_fh *fhp, u64 offset,
         u32 count, __be32 *verf)
 {
     u64         maxbytes;
     loff_t          start, end;
     struct nfsd_net     *nn;
     struct nfsd_file    *nf;
     __be32          err;
 
     err = nfsd_file_acquire(rqstp, fhp,
             NFSD_MAY_WRITE|NFSD_MAY_NOT_BREAK_LEASE, &nf);
     if (err)
         goto out;
 
     /*
      * Convert the client-provided (offset, count) range to a
      * (start, end) range. If the client-provided range falls
      * outside the maximum file size of the underlying FS,
      * clamp the sync range appropriately.
      */
     start = 0;
     end = LLONG_MAX;
     maxbytes = (u64)fhp->fh_dentry->d_sb->s_maxbytes;
     if (offset < maxbytes) {
         start = offset;
         if (count && (offset + count - 1 < maxbytes))
             end = offset + count - 1;
     }
 
     nn = net_generic(nf->nf_net, nfsd_net_id);
     if (EX_ISSYNC(fhp->fh_export)) {
         errseq_t since = READ_ONCE(nf->nf_file->f_wb_err);
         int err2;
 
         err2 = vfs_fsync_range(nf->nf_file, start, end, 0);
         switch (err2) {
         case 0:
             nfsd_copy_write_verifier(verf, nn);
             err2 = filemap_check_wb_err(nf->nf_file->f_mapping,
                             since);
             err = nfserrno(err2);
             break;
         case -EINVAL:
             err = nfserr_notsupp;
             break;
         default:
             nfsd_reset_write_verifier(nn);
             trace_nfsd_writeverf_reset(nn, rqstp, err2);
             err = nfserrno(err2);
         }
     } else
         nfsd_copy_write_verifier(verf, nn);
 
     nfsd_file_put(nf);
 out:
     return err;
 }
 
 /**
  * nfsd_create_setattr - Set a created file's attributes
  * @rqstp: RPC transaction being executed
  * @fhp: NFS filehandle of parent directory
  * @resfhp: NFS filehandle of new object
  * @attrs: requested attributes of new object
  *
  * Returns nfs_ok on success, or an nfsstat in network byte order.
  */
 __be32
 nfsd_create_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
             struct svc_fh *resfhp, struct nfsd_attrs *attrs)
 {
     struct iattr *iap = attrs->na_iattr;
     __be32 status;
 
     /*
      * Mode has already been set by file creation.
      */
     iap->ia_valid &= ~ATTR_MODE;
 
     /*
      * Setting uid/gid works only for root.  Irix appears to
      * send along the gid on create when it tries to implement
      * setgid directories via NFS:
      */
     if (!uid_eq(current_fsuid(), GLOBAL_ROOT_UID))
         iap->ia_valid &= ~(ATTR_UID|ATTR_GID);
 
     /*
      * Callers expect new file metadata to be committed even
      * if the attributes have not changed.
      */
     if (iap->ia_valid)
         status = nfsd_setattr(rqstp, resfhp, attrs, 0, (time64_t)0);
     else
         status = nfserrno(commit_metadata(resfhp));
 
     /*
      * Transactional filesystems had a chance to commit changes
      * for both parent and child simultaneously making the
      * following commit_metadata a noop in many cases.
      */
     if (!status)
         status = nfserrno(commit_metadata(fhp));
 
     /*
      * Update the new filehandle to pick up the new attributes.
      */
     if (!status)
         status = fh_update(resfhp);
 
     return status;
 }
 
 /* HPUX client sometimes creates a file in mode 000, and sets size to 0.
  * setting size to 0 may fail for some specific file systems by the permission
  * checking which requires WRITE permission but the mode is 000.
  * we ignore the resizing(to 0) on the just new created file, since the size is
  * 0 after file created.
  *
  * call this only after vfs_create() is called.
  * */
 static void
 nfsd_check_ignore_resizing(struct iattr *iap)
 {
     if ((iap->ia_valid & ATTR_SIZE) && (iap->ia_size == 0))
         iap->ia_valid &= ~ATTR_SIZE;
 }
 
 /* The parent directory should already be locked: */
 __be32
 nfsd_create_locked(struct svc_rqst *rqstp, struct svc_fh *fhp,
            char *fname, int flen, struct nfsd_attrs *attrs,
            int type, dev_t rdev, struct svc_fh *resfhp)
 {
     struct dentry   *dentry, *dchild;
     struct inode    *dirp;
     struct iattr    *iap = attrs->na_iattr;
     __be32      err;
     int     host_err;
 
     dentry = fhp->fh_dentry;
     dirp = d_inode(dentry);
 
     dchild = dget(resfhp->fh_dentry);
     err = nfsd_permission(rqstp, fhp->fh_export, dentry, NFSD_MAY_CREATE);
     if (err)
         goto out;
 
     if (!(iap->ia_valid & ATTR_MODE))
         iap->ia_mode = 0;
     iap->ia_mode = (iap->ia_mode & S_IALLUGO) | type;
 
     if (!IS_POSIXACL(dirp))
         iap->ia_mode &= ~current_umask();
 
     err = 0;
     host_err = 0;
     switch (type) {
     case S_IFREG:
         host_err = vfs_create(&init_user_ns, dirp, dchild, iap->ia_mode, true);
         if (!host_err)
             nfsd_check_ignore_resizing(iap);
         break;
     case S_IFDIR:
         host_err = vfs_mkdir(&init_user_ns, dirp, dchild, iap->ia_mode);
         if (!host_err && unlikely(d_unhashed(dchild))) {
             struct dentry *d;
             d = lookup_one_len(dchild->d_name.name,
                        dchild->d_parent,
                        dchild->d_name.len);
             if (IS_ERR(d)) {
                 host_err = PTR_ERR(d);
                 break;
             }
             if (unlikely(d_is_negative(d))) {
                 dput(d);
                 err = nfserr_serverfault;
                 goto out;
             }
             dput(resfhp->fh_dentry);
             resfhp->fh_dentry = dget(d);
             err = fh_update(resfhp);
             dput(dchild);
             dchild = d;
             if (err)
                 goto out;
         }
         break;
     case S_IFCHR:
     case S_IFBLK:
     case S_IFIFO:
     case S_IFSOCK:
         host_err = vfs_mknod(&init_user_ns, dirp, dchild,
                      iap->ia_mode, rdev);
         break;
     default:
         printk(KERN_WARNING "nfsd: bad file type %o in nfsd_create\n",
                type);
         host_err = -EINVAL;
     }
     if (host_err < 0)
         goto out_nfserr;
 
     err = nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
 
 out:
     dput(dchild);
     return err;
 
 out_nfserr:
     err = nfserrno(host_err);
     goto out;
 }
 
 /*
  * Create a filesystem object (regular, directory, special).
  * Note that the parent directory is left locked.
  *
  * N.B. Every call to nfsd_create needs an fh_put for _both_ fhp and resfhp
  */
 __be32
 nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
         char *fname, int flen, struct nfsd_attrs *attrs,
         int type, dev_t rdev, struct svc_fh *resfhp)
 {
     struct dentry   *dentry, *dchild = NULL;
     __be32      err;
     int     host_err;
 
     if (isdotent(fname, flen))
         return nfserr_exist;
 
     err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_NOP);
     if (err)
         return err;
 
     dentry = fhp->fh_dentry;
 
     host_err = fh_want_write(fhp);
     if (host_err)
         return nfserrno(host_err);
 
     inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
     dchild = lookup_one_len(fname, dentry, flen);
     host_err = PTR_ERR(dchild);
     if (IS_ERR(dchild)) {
         err = nfserrno(host_err);
         goto out_unlock;
     }
     err = fh_compose(resfhp, fhp->fh_export, dchild, fhp);
     /*
      * We unconditionally drop our ref to dchild as fh_compose will have
      * already grabbed its own ref for it.
      */
     dput(dchild);
     if (err)
         goto out_unlock;
     fh_fill_pre_attrs(fhp);
     err = nfsd_create_locked(rqstp, fhp, fname, flen, attrs, type,
                  rdev, resfhp);
     fh_fill_post_attrs(fhp);
 out_unlock:
     inode_unlock(dentry->d_inode);
     return err;
 }
 
 /*
  * Read a symlink. On entry, *lenp must contain the maximum path length that
  * fits into the buffer. On return, it contains the true length.
  * N.B. After this call fhp needs an fh_put
  */
 __be32
 nfsd_readlink(struct svc_rqst *rqstp, struct svc_fh *fhp, char *buf, int *lenp)
 {
     __be32      err;
     const char *link;
     struct path path;
     DEFINE_DELAYED_CALL(done);
     int len;
 
     err = fh_verify(rqstp, fhp, S_IFLNK, NFSD_MAY_NOP);
     if (unlikely(err))
         return err;
 
     path.mnt = fhp->fh_export->ex_path.mnt;
     path.dentry = fhp->fh_dentry;
 
     if (unlikely(!d_is_symlink(path.dentry)))
         return nfserr_inval;
 
     touch_atime(&path);
 
     link = vfs_get_link(path.dentry, &done);
     if (IS_ERR(link))
         return nfserrno(PTR_ERR(link));
 
     len = strlen(link);
     if (len < *lenp)
         *lenp = len;
     memcpy(buf, link, *lenp);
     do_delayed_call(&done);
     return 0;
 }
 
 /**
  * nfsd_symlink - Create a symlink and look up its inode
  * @rqstp: RPC transaction being executed
  * @fhp: NFS filehandle of parent directory
  * @fname: filename of the new symlink
  * @flen: length of @fname
  * @path: content of the new symlink (NUL-terminated)
  * @attrs: requested attributes of new object
  * @resfhp: NFS filehandle of new object
  *
  * N.B. After this call _both_ fhp and resfhp need an fh_put
  *
  * Returns nfs_ok on success, or an nfsstat in network byte order.
  */
 __be32
 nfsd_symlink(struct svc_rqst *rqstp, struct svc_fh *fhp,
          char *fname, int flen,
          char *path, struct nfsd_attrs *attrs,
          struct svc_fh *resfhp)
 {
     struct dentry   *dentry, *dnew;
     __be32      err, cerr;
     int     host_err;
 
     err = nfserr_noent;
     if (!flen || path[0] == '\0')
         goto out;
     err = nfserr_exist;
     if (isdotent(fname, flen))
         goto out;
 
     err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
     if (err)
         goto out;
 
     host_err = fh_want_write(fhp);
     if (host_err) {
         err = nfserrno(host_err);
         goto out;
     }
 
     dentry = fhp->fh_dentry;
     inode_lock_nested(dentry->d_inode, I_MUTEX_PARENT);
     dnew = lookup_one_len(fname, dentry, flen);
     if (IS_ERR(dnew)) {
         err = nfserrno(PTR_ERR(dnew));
         inode_unlock(dentry->d_inode);
         goto out_drop_write;
     }
     fh_fill_pre_attrs(fhp);
     host_err = vfs_symlink(&init_user_ns, d_inode(dentry), dnew, path);
     err = nfserrno(host_err);
     cerr = fh_compose(resfhp, fhp->fh_export, dnew, fhp);
     if (!err)
         nfsd_create_setattr(rqstp, fhp, resfhp, attrs);
     fh_fill_post_attrs(fhp);
     inode_unlock(dentry->d_inode);
     if (!err)
         err = nfserrno(commit_metadata(fhp));
     dput(dnew);
     if (err==0) err = cerr;
 out_drop_write:
     fh_drop_write(fhp);
 out:
     return err;
 }
 
 /*
  * Create a hardlink
  * N.B. After this call _both_ ffhp and tfhp need an fh_put
  */
 __be32
 nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
                 char *name, int len, struct svc_fh *tfhp)
 {
     struct dentry   *ddir, *dnew, *dold;
     struct inode    *dirp;
     __be32      err;
     int     host_err;
 
     err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
     if (err)
         goto out;
     err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
     if (err)
         goto out;
     err = nfserr_isdir;
     if (d_is_dir(tfhp->fh_dentry))
         goto out;
     err = nfserr_perm;
     if (!len)
         goto out;
     err = nfserr_exist;
     if (isdotent(name, len))
         goto out;
 
     host_err = fh_want_write(tfhp);
     if (host_err) {
         err = nfserrno(host_err);
         goto out;
     }
 
     ddir = ffhp->fh_dentry;
     dirp = d_inode(ddir);
     inode_lock_nested(dirp, I_MUTEX_PARENT);
 
     dnew = lookup_one_len(name, ddir, len);
     if (IS_ERR(dnew)) {
         err = nfserrno(PTR_ERR(dnew));
         goto out_unlock;
     }
 
     dold = tfhp->fh_dentry;
 
     err = nfserr_noent;
     if (d_really_is_negative(dold))
         goto out_dput;
     fh_fill_pre_attrs(ffhp);
     host_err = vfs_link(dold, &init_user_ns, dirp, dnew, NULL);
     fh_fill_post_attrs(ffhp);
     inode_unlock(dirp);
     if (!host_err) {
         err = nfserrno(commit_metadata(ffhp));
         if (!err)
             err = nfserrno(commit_metadata(tfhp));
     } else {
         if (host_err == -EXDEV && rqstp->rq_vers == 2)
             err = nfserr_acces;
         else
             err = nfserrno(host_err);
     }
     dput(dnew);
 out_drop_write:
     fh_drop_write(tfhp);
 out:
     return err;
 
 out_dput:
     dput(dnew);
 out_unlock:
     inode_unlock(dirp);
     goto out_drop_write;
 }
 
 static void
 nfsd_close_cached_files(struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
 
     if (inode && S_ISREG(inode->i_mode))
         nfsd_file_close_inode_sync(inode);
 }
 
 static bool
 nfsd_has_cached_files(struct dentry *dentry)
 {
     bool        ret = false;
     struct inode *inode = d_inode(dentry);
 
     if (inode && S_ISREG(inode->i_mode))
         ret = nfsd_file_is_cached(inode);
     return ret;
 }
 
 /*
  * Rename a file
  * N.B. After this call _both_ ffhp and tfhp need an fh_put
  */
 __be32
 nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
                 struct svc_fh *tfhp, char *tname, int tlen)
 {
     struct dentry   *fdentry, *tdentry, *odentry, *ndentry, *trap;
     struct inode    *fdir, *tdir;
     __be32      err;
     int     host_err;
     bool        close_cached = false;
 
     err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);
     if (err)
         goto out;
     err = fh_verify(rqstp, tfhp, S_IFDIR, NFSD_MAY_CREATE);
     if (err)
         goto out;
 
     fdentry = ffhp->fh_dentry;
     fdir = d_inode(fdentry);
 
     tdentry = tfhp->fh_dentry;
     tdir = d_inode(tdentry);
 
     err = nfserr_perm;
     if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))
         goto out;
 
 retry:
     host_err = fh_want_write(ffhp);
     if (host_err) {
         err = nfserrno(host_err);
         goto out;
     }
 
     trap = lock_rename(tdentry, fdentry);
     fh_fill_pre_attrs(ffhp);
     fh_fill_pre_attrs(tfhp);
 
     odentry = lookup_one_len(fname, fdentry, flen);
     host_err = PTR_ERR(odentry);
     if (IS_ERR(odentry))
         goto out_nfserr;
 
     host_err = -ENOENT;
     if (d_really_is_negative(odentry))
         goto out_dput_old;
     host_err = -EINVAL;
     if (odentry == trap)
         goto out_dput_old;
 
     ndentry = lookup_one_len(tname, tdentry, tlen);
     host_err = PTR_ERR(ndentry);
     if (IS_ERR(ndentry))
         goto out_dput_old;
     host_err = -ENOTEMPTY;
     if (ndentry == trap)
         goto out_dput_new;
 
     host_err = -EXDEV;
     if (ffhp->fh_export->ex_path.mnt != tfhp->fh_export->ex_path.mnt)
         goto out_dput_new;
     if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)
         goto out_dput_new;
 
     if ((ndentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK) &&
         nfsd_has_cached_files(ndentry)) {
         close_cached = true;
         goto out_dput_old;
     } else {
         struct renamedata rd = {
             .old_mnt_userns = &init_user_ns,
             .old_dir    = fdir,
             .old_dentry = odentry,
             .new_mnt_userns = &init_user_ns,
             .new_dir    = tdir,
             .new_dentry = ndentry,
         };
         host_err = vfs_rename(&rd);
         if (!host_err) {
             host_err = commit_metadata(tfhp);
             if (!host_err)
                 host_err = commit_metadata(ffhp);
         }
     }
  out_dput_new:
     dput(ndentry);
  out_dput_old:
     dput(odentry);
  out_nfserr:
     err = nfserrno(host_err);
 
     if (!close_cached) {
         fh_fill_post_attrs(ffhp);
         fh_fill_post_attrs(tfhp);
     }
     unlock_rename(tdentry, fdentry);
     fh_drop_write(ffhp);
 
     /*
      * If the target dentry has cached open files, then we need to try to
      * close them prior to doing the rename. Flushing delayed fput
      * shouldn't be done with locks held however, so we delay it until this
      * point and then reattempt the whole shebang.
      */
     if (close_cached) {
         close_cached = false;
         nfsd_close_cached_files(ndentry);
         dput(ndentry);
         goto retry;
     }
 out:
     return err;
 }
 
 /*
  * Unlink a file or directory
  * N.B. After this call fhp needs an fh_put
  */
 __be32
 nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type,
                 char *fname, int flen)
 {
     struct dentry   *dentry, *rdentry;
     struct inode    *dirp;
     struct inode    *rinode;
     __be32      err;
     int     host_err;
 
     err = nfserr_acces;
     if (!flen || isdotent(fname, flen))
         goto out;
     err = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_REMOVE);
     if (err)
         goto out;
 
     host_err = fh_want_write(fhp);
     if (host_err)
         goto out_nfserr;
 
     dentry = fhp->fh_dentry;
     dirp = d_inode(dentry);
     inode_lock_nested(dirp, I_MUTEX_PARENT);
 
     rdentry = lookup_one_len(fname, dentry, flen);
     host_err = PTR_ERR(rdentry);
     if (IS_ERR(rdentry))
         goto out_unlock;
 
     if (d_really_is_negative(rdentry)) {
         dput(rdentry);
         host_err = -ENOENT;
         goto out_unlock;
     }
     rinode = d_inode(rdentry);
     ihold(rinode);
 
     if (!type)
         type = d_inode(rdentry)->i_mode & S_IFMT;
 
     fh_fill_pre_attrs(fhp);
     if (type != S_IFDIR) {
         if (rdentry->d_sb->s_export_op->flags & EXPORT_OP_CLOSE_BEFORE_UNLINK)
             nfsd_close_cached_files(rdentry);
         host_err = vfs_unlink(&init_user_ns, dirp, rdentry, NULL);
     } else {
         host_err = vfs_rmdir(&init_user_ns, dirp, rdentry);
     }
     fh_fill_post_attrs(fhp);
 
     inode_unlock(dirp);
     if (!host_err)
         host_err = commit_metadata(fhp);
     dput(rdentry);
     iput(rinode);    /* truncate the inode here */
 
 out_drop_write:
     fh_drop_write(fhp);
 out_nfserr:
     if (host_err == -EBUSY) {
         /* name is mounted-on. There is no perfect
          * error status.
          */
         if (nfsd_v4client(rqstp))
             err = nfserr_file_open;
         else
             err = nfserr_acces;
     } else {
         err = nfserrno(host_err);
     }
 out:
     return err;
 out_unlock:
     inode_unlock(dirp);
     goto out_drop_write;
 }
 
 /*
  * We do this buffering because we must not call back into the file
  * system's ->lookup() method from the filldir callback. That may well
  * deadlock a number of file systems.
  *
  * This is based heavily on the implementation of same in XFS.
  */
 struct buffered_dirent {
     u64     ino;
     loff_t      offset;
     int     namlen;
     unsigned int    d_type;
     char        name[];
 };
 
 struct readdir_data {
     struct dir_context ctx;
     char        *dirent;
     size_t      used;
     int     full;
 };
 
 static int nfsd_buffered_filldir(struct dir_context *ctx, const char *name,
                  int namlen, loff_t offset, u64 ino,
                  unsigned int d_type)
 {
     struct readdir_data *buf =
         container_of(ctx, struct readdir_data, ctx);
     struct buffered_dirent *de = (void *)(buf->dirent + buf->used);
     unsigned int reclen;
 
     reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
     if (buf->used + reclen > PAGE_SIZE) {
         buf->full = 1;
         return -EINVAL;
     }
 
     de->namlen = namlen;
     de->offset = offset;
     de->ino = ino;
     de->d_type = d_type;
     memcpy(de->name, name, namlen);
     buf->used += reclen;
 
     return 0;
 }
 
 static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
                     nfsd_filldir_t func, struct readdir_cd *cdp,
                     loff_t *offsetp)
 {
     struct buffered_dirent *de;
     int host_err;
     int size;
     loff_t offset;
     struct readdir_data buf = {
         .ctx.actor = nfsd_buffered_filldir,
         .dirent = (void *)__get_free_page(GFP_KERNEL)
     };
 
     if (!buf.dirent)
         return nfserrno(-ENOMEM);
 
     offset = *offsetp;
 
     while (1) {
         unsigned int reclen;
 
         cdp->err = nfserr_eof; /* will be cleared on successful read */
         buf.used = 0;
         buf.full = 0;
 
         host_err = iterate_dir(file, &buf.ctx);
         if (buf.full)
             host_err = 0;
 
         if (host_err < 0)
             break;
 
         size = buf.used;
 
         if (!size)
             break;
 
         de = (struct buffered_dirent *)buf.dirent;
         while (size > 0) {
             offset = de->offset;
 
             if (func(cdp, de->name, de->namlen, de->offset,
                  de->ino, de->d_type))
                 break;
 
             if (cdp->err != nfs_ok)
                 break;
 
             trace_nfsd_dirent(fhp, de->ino, de->name, de->namlen);
 
             reclen = ALIGN(sizeof(*de) + de->namlen,
                        sizeof(u64));
             size -= reclen;
             de = (struct buffered_dirent *)((char *)de + reclen);
         }
         if (size > 0) /* We bailed out early */
             break;
 
         offset = vfs_llseek(file, 0, SEEK_CUR);
     }
 
     free_page((unsigned long)(buf.dirent));
 
     if (host_err)
         return nfserrno(host_err);
 
     *offsetp = offset;
     return cdp->err;
 }
 
 /*
  * Read entries from a directory.
  * The  NFSv3/4 verifier we ignore for now.
  */
 __be32
 nfsd_readdir(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t *offsetp, 
          struct readdir_cd *cdp, nfsd_filldir_t func)
 {
     __be32      err;
     struct file *file;
     loff_t      offset = *offsetp;
     int             may_flags = NFSD_MAY_READ;
 
     /* NFSv2 only supports 32 bit cookies */
     if (rqstp->rq_vers > 2)
         may_flags |= NFSD_MAY_64BIT_COOKIE;
 
     err = nfsd_open(rqstp, fhp, S_IFDIR, may_flags, &file);
     if (err)
         goto out;
 
     offset = vfs_llseek(file, offset, SEEK_SET);
     if (offset < 0) {
         err = nfserrno((int)offset);
         goto out_close;
     }
 
     err = nfsd_buffered_readdir(file, fhp, func, cdp, offsetp);
 
     if (err == nfserr_eof || err == nfserr_toosmall)
         err = nfs_ok; /* can still be found in ->err */
 out_close:
     fput(file);
 out:
     return err;
 }
 
 /*
  * Get file system stats
  * N.B. After this call fhp needs an fh_put
  */
 __be32
 nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
 {
     __be32 err;
 
     err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
     if (!err) {
         struct path path = {
             .mnt    = fhp->fh_export->ex_path.mnt,
             .dentry = fhp->fh_dentry,
         };
         if (vfs_statfs(&path, stat))
             err = nfserr_io;
     }
     return err;
 }
 
 static int exp_rdonly(struct svc_rqst *rqstp, struct svc_export *exp)
 {
     return nfsexp_flags(rqstp, exp) & NFSEXP_READONLY;
 }
 
 #ifdef CONFIG_NFSD_V4
 /*
  * Helper function to translate error numbers. In the case of xattr operations,
  * some error codes need to be translated outside of the standard translations.
  *
  * ENODATA needs to be translated to nfserr_noxattr.
  * E2BIG to nfserr_xattr2big.
  *
  * Additionally, vfs_listxattr can return -ERANGE. This means that the
  * file has too many extended attributes to retrieve inside an
  * XATTR_LIST_MAX sized buffer. This is a bug in the xattr implementation:
  * filesystems will allow the adding of extended attributes until they hit
  * their own internal limit. This limit may be larger than XATTR_LIST_MAX.
  * So, at that point, the attributes are present and valid, but can't
  * be retrieved using listxattr, since the upper level xattr code enforces
  * the XATTR_LIST_MAX limit.
  *
  * This bug means that we need to deal with listxattr returning -ERANGE. The
  * best mapping is to return TOOSMALL.
  */
 static __be32
 nfsd_xattr_errno(int err)
 {
     switch (err) {
     case -ENODATA:
         return nfserr_noxattr;
     case -E2BIG:
         return nfserr_xattr2big;
     case -ERANGE:
         return nfserr_toosmall;
     }
     return nfserrno(err);
 }
 
 /*
  * Retrieve the specified user extended attribute. To avoid always
  * having to allocate the maximum size (since we are not getting
  * a maximum size from the RPC), do a probe + alloc. Hold a reader
  * lock on i_rwsem to prevent the extended attribute from changing
  * size while we're doing this.
  */
 __be32
 nfsd_getxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
           void **bufp, int *lenp)
 {
     ssize_t len;
     __be32 err;
     char *buf;
     struct inode *inode;
     struct dentry *dentry;
 
     err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
     if (err)
         return err;
 
     err = nfs_ok;
     dentry = fhp->fh_dentry;
     inode = d_inode(dentry);
 
     inode_lock_shared(inode);
 
     len = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
 
     /*
      * Zero-length attribute, just return.
      */
     if (len == 0) {
         *bufp = NULL;
         *lenp = 0;
         goto out;
     }
 
     if (len < 0) {
         err = nfsd_xattr_errno(len);
         goto out;
     }
 
     if (len > *lenp) {
         err = nfserr_toosmall;
         goto out;
     }
 
     buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
     if (buf == NULL) {
         err = nfserr_jukebox;
         goto out;
     }
 
     len = vfs_getxattr(&init_user_ns, dentry, name, buf, len);
     if (len <= 0) {
         kvfree(buf);
         buf = NULL;
         err = nfsd_xattr_errno(len);
     }
 
     *lenp = len;
     *bufp = buf;
 
 out:
     inode_unlock_shared(inode);
 
     return err;
 }
 
 /*
  * Retrieve the xattr names. Since we can't know how many are
  * user extended attributes, we must get all attributes here,
  * and have the XDR encode filter out the "user." ones.
  *
  * While this could always just allocate an XATTR_LIST_MAX
  * buffer, that's a waste, so do a probe + allocate. To
  * avoid any changes between the probe and allocate, wrap
  * this in inode_lock.
  */
 __be32
 nfsd_listxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char **bufp,
            int *lenp)
 {
     ssize_t len;
     __be32 err;
     char *buf;
     struct inode *inode;
     struct dentry *dentry;
 
     err = fh_verify(rqstp, fhp, 0, NFSD_MAY_READ);
     if (err)
         return err;
 
     dentry = fhp->fh_dentry;
     inode = d_inode(dentry);
     *lenp = 0;
 
     inode_lock_shared(inode);
 
     len = vfs_listxattr(dentry, NULL, 0);
     if (len <= 0) {
         err = nfsd_xattr_errno(len);
         goto out;
     }
 
     if (len > XATTR_LIST_MAX) {
         err = nfserr_xattr2big;
         goto out;
     }
 
     /*
      * We're holding i_rwsem - use GFP_NOFS.
      */
     buf = kvmalloc(len, GFP_KERNEL | GFP_NOFS);
     if (buf == NULL) {
         err = nfserr_jukebox;
         goto out;
     }
 
     len = vfs_listxattr(dentry, buf, len);
     if (len <= 0) {
         kvfree(buf);
         err = nfsd_xattr_errno(len);
         goto out;
     }
 
     *lenp = len;
     *bufp = buf;
 
     err = nfs_ok;
 out:
     inode_unlock_shared(inode);
 
     return err;
 }
 
 /**
  * nfsd_removexattr - Remove an extended attribute
  * @rqstp: RPC transaction being executed
  * @fhp: NFS filehandle of object with xattr to remove
  * @name: name of xattr to remove (NUL-terminate)
  *
  * Pass in a NULL pointer for delegated_inode, and let the client deal
  * with NFS4ERR_DELAY (same as with e.g. setattr and remove).
  *
  * Returns nfs_ok on success, or an nfsstat in network byte order.
  */
 __be32
 nfsd_removexattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name)
 {
     __be32 err;
     int ret;
 
     err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
     if (err)
         return err;
 
     ret = fh_want_write(fhp);
     if (ret)
         return nfserrno(ret);
 
     inode_lock(fhp->fh_dentry->d_inode);
     fh_fill_pre_attrs(fhp);
 
     ret = __vfs_removexattr_locked(&init_user_ns, fhp->fh_dentry,
                        name, NULL);
 
     fh_fill_post_attrs(fhp);
     inode_unlock(fhp->fh_dentry->d_inode);
     fh_drop_write(fhp);
 
     return nfsd_xattr_errno(ret);
 }
 
 __be32
 nfsd_setxattr(struct svc_rqst *rqstp, struct svc_fh *fhp, char *name,
           void *buf, u32 len, u32 flags)
 {
     __be32 err;
     int ret;
 
     err = fh_verify(rqstp, fhp, 0, NFSD_MAY_WRITE);
     if (err)
         return err;
 
     ret = fh_want_write(fhp);
     if (ret)
         return nfserrno(ret);
     inode_lock(fhp->fh_dentry->d_inode);
     fh_fill_pre_attrs(fhp);
 
     ret = __vfs_setxattr_locked(&init_user_ns, fhp->fh_dentry, name, buf,
                     len, flags, NULL);
     fh_fill_post_attrs(fhp);
     inode_unlock(fhp->fh_dentry->d_inode);
     fh_drop_write(fhp);
 
     return nfsd_xattr_errno(ret);
 }
 #endif
 
 /*
  * Check for a user's access permissions to this inode.
  */
 __be32
 nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp,
                     struct dentry *dentry, int acc)
 {
     struct inode    *inode = d_inode(dentry);
     int     err;
 
     if ((acc & NFSD_MAY_MASK) == NFSD_MAY_NOP)
         return 0;
 #if 0
     dprintk("nfsd: permission 0x%x%s%s%s%s%s%s%s mode 0%o%s%s%s\n",
         acc,
         (acc & NFSD_MAY_READ)?  " read"  : "",
         (acc & NFSD_MAY_WRITE)? " write" : "",
         (acc & NFSD_MAY_EXEC)?  " exec"  : "",
         (acc & NFSD_MAY_SATTR)? " sattr" : "",
         (acc & NFSD_MAY_TRUNC)? " trunc" : "",
         (acc & NFSD_MAY_LOCK)?  " lock"  : "",
         (acc & NFSD_MAY_OWNER_OVERRIDE)? " owneroverride" : "",
         inode->i_mode,
         IS_IMMUTABLE(inode)?    " immut" : "",
         IS_APPEND(inode)?   " append" : "",
         __mnt_is_readonly(exp->ex_path.mnt)?    " ro" : "");
     dprintk("      owner %d/%d user %d/%d\n",
         inode->i_uid, inode->i_gid, current_fsuid(), current_fsgid());
 #endif
 
     /* Normally we reject any write/sattr etc access on a read-only file
      * system.  But if it is IRIX doing check on write-access for a 
      * device special file, we ignore rofs.
      */
     if (!(acc & NFSD_MAY_LOCAL_ACCESS))
         if (acc & (NFSD_MAY_WRITE | NFSD_MAY_SATTR | NFSD_MAY_TRUNC)) {
             if (exp_rdonly(rqstp, exp) ||
                 __mnt_is_readonly(exp->ex_path.mnt))
                 return nfserr_rofs;
             if (/* (acc & NFSD_MAY_WRITE) && */ IS_IMMUTABLE(inode))
                 return nfserr_perm;
         }
     if ((acc & NFSD_MAY_TRUNC) && IS_APPEND(inode))
         return nfserr_perm;
 
     if (acc & NFSD_MAY_LOCK) {
         /* If we cannot rely on authentication in NLM requests,
          * just allow locks, otherwise require read permission, or
          * ownership
          */
         if (exp->ex_flags & NFSEXP_NOAUTHNLM)
             return 0;
         else
             acc = NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE;
     }
     /*
      * The file owner always gets access permission for accesses that
      * would normally be checked at open time. This is to make
      * file access work even when the client has done a fchmod(fd, 0).
      *
      * However, `cp foo bar' should fail nevertheless when bar is
      * readonly. A sensible way to do this might be to reject all
      * attempts to truncate a read-only file, because a creat() call
      * always implies file truncation.
      * ... but this isn't really fair.  A process may reasonably call
      * ftruncate on an open file descriptor on a file with perm 000.
      * We must trust the client to do permission checking - using "ACCESS"
      * with NFSv3.
      */
     if ((acc & NFSD_MAY_OWNER_OVERRIDE) &&
         uid_eq(inode->i_uid, current_fsuid()))
         return 0;
 
     /* This assumes  NFSD_MAY_{READ,WRITE,EXEC} == MAY_{READ,WRITE,EXEC} */
     err = inode_permission(&init_user_ns, inode,
                    acc & (MAY_READ | MAY_WRITE | MAY_EXEC));
 
     /* Allow read access to binaries even when mode 111 */
     if (err == -EACCES && S_ISREG(inode->i_mode) &&
          (acc == (NFSD_MAY_READ | NFSD_MAY_OWNER_OVERRIDE) ||
           acc == (NFSD_MAY_READ | NFSD_MAY_READ_IF_EXEC)))
         err = inode_permission(&init_user_ns, inode, MAY_EXEC);
 
     return err? nfserrno(err) : 0;
 }

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