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 #ifdef __KERNEL__
  24
  25 #define DEBUG_SUBSYSTEM S_FILTER
  26
  27 #include <linux/fs.h>
  28 #include <libcfs/libcfs.h>
  29 #include <lvfs.h>
  30
  31 /* refine later and change to seqlock or simlar from libcfs */
  32 /* Debugging check only needed during development */
  33 #ifdef OBD_CTXT_DEBUG
  34 # define ASSERT_CTXT_MAGIC(magic) LASSERT((magic) == OBD_RUN_CTXT_MAGIC)
  35 # define ASSERT_NOT_KERNEL_CTXT(msg) LASSERTF(!segment_eq(get_fs(), get_ds()),\
  36                                               msg)
  37 # define ASSERT_KERNEL_CTXT(msg) LASSERTF(segment_eq(get_fs(), get_ds()), msg)
  38 #else
  39 # define ASSERT_CTXT_MAGIC(magic) do {} while(0)
  40 # define ASSERT_NOT_KERNEL_CTXT(msg) do {} while(0)
  41 # define ASSERT_KERNEL_CTXT(msg) do {} while(0)
  42 #endif
  43
  44 /* push / pop to root of obd store */
  45 void push_ctxt(struct lvfs_run_ctxt *save, struct lvfs_run_ctxt *new_ctx)
  46 {
  47         /* if there is underlaying dt_device then push_ctxt is not needed */
  48         if (new_ctx->dt != NULL)
  49                 return;
  50
  51         //ASSERT_NOT_KERNEL_CTXT("already in kernel context!\n");
  52         ASSERT_CTXT_MAGIC(new_ctx->magic);
  53         OBD_SET_CTXT_MAGIC(save);
  54
  55         save->fs = get_fs();
  56         LASSERT(d_count(current->fs->pwd.dentry));
  57         LASSERT(d_count(new_ctx->pwd));
  58         save->pwd = dget(current->fs->pwd.dentry);
  59         save->pwdmnt = mntget(current->fs->pwd.mnt);
  60         save->umask = current_umask();
  61
  62         LASSERT(save->pwd);
  63         LASSERT(save->pwdmnt);
  64         LASSERT(new_ctx->pwd);
  65         LASSERT(new_ctx->pwdmnt);
  66
  67         current->fs->umask = 0; /* umask already applied on client */
  68         set_fs(new_ctx->fs);
  69         ll_set_fs_pwd(current->fs, new_ctx->pwdmnt, new_ctx->pwd);
  70 }
  71 EXPORT_SYMBOL(push_ctxt);
  72
  73 void pop_ctxt(struct lvfs_run_ctxt *saved, struct lvfs_run_ctxt *new_ctx)
  74 {
  75         /* if there is underlaying dt_device then pop_ctxt is not needed */
  76         if (new_ctx->dt != NULL)
  77                 return;
  78
  79         ASSERT_CTXT_MAGIC(saved->magic);
  80         ASSERT_KERNEL_CTXT("popping non-kernel context!\n");
  81
  82         LASSERTF(current->fs->pwd.dentry == new_ctx->pwd, "%p != %p\n",
  83                  current->fs->pwd.dentry, new_ctx->pwd);
  84         LASSERTF(current->fs->pwd.mnt == new_ctx->pwdmnt, "%p != %p\n",
  85                  current->fs->pwd.mnt, new_ctx->pwdmnt);
  86
  87         set_fs(saved->fs);
  88         ll_set_fs_pwd(current->fs, saved->pwdmnt, saved->pwd);
  89
  90         dput(saved->pwd);
  91         mntput(saved->pwdmnt);
  92         current->fs->umask = saved->umask;
  93 }
  94 EXPORT_SYMBOL(pop_ctxt);
  95
  96 /* utility to rename a file */
  97 int lustre_rename(struct dentry *dir, struct vfsmount *mnt,
  98                   char *oldname, char *newname)
  99 {
 100         struct dentry *dchild_old, *dchild_new;
 101         int err = 0;
 102         ENTRY;
 103
 104         ASSERT_KERNEL_CTXT("kernel doing rename outside kernel context\n");
 105         CDEBUG(D_INODE, "renaming file %.*s to %.*s\n",
 106                (int)strlen(oldname), oldname, (int)strlen(newname), newname);
 107
 108         dchild_old = ll_lookup_one_len(oldname, dir, strlen(oldname));
 109         if (IS_ERR(dchild_old))
 110                 RETURN(PTR_ERR(dchild_old));
 111
 112         if (!dchild_old->d_inode)
 113                 GOTO(put_old, err = -ENOENT);
 114
 115         dchild_new = ll_lookup_one_len(newname, dir, strlen(newname));
 116         if (IS_ERR(dchild_new))
 117                 GOTO(put_old, err = PTR_ERR(dchild_new));
 118
 119         err = ll_vfs_rename(dir->d_inode, dchild_old, dir->d_inode, dchild_new);
 120
 121         dput(dchild_new);
 122 put_old:
 123         dput(dchild_old);
 124         RETURN(err);
 125 }
 126 #endif /* __KERNEL__ */