lustre/ptlrpc/sec_ctx.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  *
  19  * http://www.gnu.org/licenses/gpl-2.0.html
  20  *
  21  * GPL HEADER END
  22  */
  23
  24 #define DEBUG_SUBSYSTEM S_FILTER
  25
  26 #include <linux/fs.h>
  27 #include <libcfs/libcfs.h>
  28 #include <lvfs.h>
  29 #include <obd_class.h>
  30
  31 #include "ptlrpc_internal.h"
  32
  33 /* refine later and change to seqlock or simlar from libcfs */
  34 /* Debugging check only needed during development */
  35 #ifdef OBD_CTXT_DEBUG
  36 # define ASSERT_CTXT_MAGIC(magic) LASSERT((magic) == OBD_RUN_CTXT_MAGIC)
  37 # define ASSERT_NOT_KERNEL_CTXT(msg) LASSERTF(!segment_eq(get_fs(), get_ds()),\
  38                                               msg)
  39 # define ASSERT_KERNEL_CTXT(msg) LASSERTF(segment_eq(get_fs(), get_ds()), msg)
  40 #else
  41 # define ASSERT_CTXT_MAGIC(magic) do {} while(0)
  42 # define ASSERT_NOT_KERNEL_CTXT(msg) do {} while(0)
  43 # define ASSERT_KERNEL_CTXT(msg) do {} while(0)
  44 #endif
  45
  46 /* push / pop to root of obd store */
  47 void push_ctxt(struct lvfs_run_ctxt *save, struct lvfs_run_ctxt *new_ctx)
  48 {
  49         /* if there is underlaying dt_device then push_ctxt is not needed */
  50         if (new_ctx->dt != NULL)
  51                 return;
  52
  53         //ASSERT_NOT_KERNEL_CTXT("already in kernel context!\n");
  54         ASSERT_CTXT_MAGIC(new_ctx->magic);
  55         OBD_SET_CTXT_MAGIC(save);
  56
  57         save->fs = get_fs();
  58         LASSERT(ll_d_count(current->fs->pwd.dentry));
  59         LASSERT(ll_d_count(new_ctx->pwd));
  60         save->pwd = dget(current->fs->pwd.dentry);
  61         save->pwdmnt = mntget(current->fs->pwd.mnt);
  62         save->umask = current_umask();
  63
  64         LASSERT(save->pwd);
  65         LASSERT(save->pwdmnt);
  66         LASSERT(new_ctx->pwd);
  67         LASSERT(new_ctx->pwdmnt);
  68
  69         current->fs->umask = 0; /* umask already applied on client */
  70         set_fs(new_ctx->fs);
  71         ll_set_fs_pwd(current->fs, new_ctx->pwdmnt, new_ctx->pwd);
  72 }
  73 EXPORT_SYMBOL(push_ctxt);
  74
  75 void pop_ctxt(struct lvfs_run_ctxt *saved, struct lvfs_run_ctxt *new_ctx)
  76 {
  77         /* if there is underlaying dt_device then pop_ctxt is not needed */
  78         if (new_ctx->dt != NULL)
  79                 return;
  80
  81         ASSERT_CTXT_MAGIC(saved->magic);
  82         ASSERT_KERNEL_CTXT("popping non-kernel context!\n");
  83
  84         LASSERTF(current->fs->pwd.dentry == new_ctx->pwd, "%p != %p\n",
  85                  current->fs->pwd.dentry, new_ctx->pwd);
  86         LASSERTF(current->fs->pwd.mnt == new_ctx->pwdmnt, "%p != %p\n",
  87                  current->fs->pwd.mnt, new_ctx->pwdmnt);
  88
  89         set_fs(saved->fs);
  90         ll_set_fs_pwd(current->fs, saved->pwdmnt, saved->pwd);
  91
  92         dput(saved->pwd);
  93         mntput(saved->pwdmnt);
  94         current->fs->umask = saved->umask;
  95 }
  96 EXPORT_SYMBOL(pop_ctxt);
  97
  98 /* utility to rename a file */
  99 int lustre_rename(struct dentry *dir, struct vfsmount *mnt,
 100                   char *oldname, char *newname)
 101 {
 102         struct dentry *dchild_old, *dchild_new;
 103         int err = 0;
 104         ENTRY;
 105
 106         ASSERT_KERNEL_CTXT("kernel doing rename outside kernel context\n");
 107         CDEBUG(D_INODE, "renaming file %.*s to %.*s\n",
 108                (int)strlen(oldname), oldname, (int)strlen(newname), newname);
 109
 110         dchild_old = ll_lookup_one_len(oldname, dir, strlen(oldname));
 111         if (IS_ERR(dchild_old))
 112                 RETURN(PTR_ERR(dchild_old));
 113
 114         if (!dchild_old->d_inode)
 115                 GOTO(put_old, err = -ENOENT);
 116
 117         dchild_new = ll_lookup_one_len(newname, dir, strlen(newname));
 118         if (IS_ERR(dchild_new))
 119                 GOTO(put_old, err = PTR_ERR(dchild_new));
 120
 121         err = ll_vfs_rename(dir->d_inode, dchild_old, dir->d_inode, dchild_new);
 122
 123         dput(dchild_new);
 124 put_old:
 125         dput(dchild_old);
 126         RETURN(err);
 127 }