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