lustre/lib/simple.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  *  lib/simple.c
   5  *
   6  * Copyright (C) 2002  Cluster File Systems, Inc.
   7  *
   8  * This code is issued under the GNU General Public License.
   9  * See the file COPYING in this distribution
  10  *
  11  * by Peter Braam <braam@clusterfs.com>
  12  * and Andreas Dilger <adilger@clusterfs.com>
  13  */
  14
  15 #define EXPORT_SYMTAB
  16
  17 #include <linux/version.h>
  18 #include <linux/fs.h>
  19 #include <asm/unistd.h>
  20
  21 #define DEBUG_SUBSYSTEM S_FILTER
  22
  23 #include <linux/obd_support.h>
  24 #include <linux/obd.h>
  25 #include <linux/lustre_mds.h>
  26 #include <linux/lustre_lib.h>
  27 #include <linux/lustre_net.h>
  28
  29 #ifdef OBD_CTXT_DEBUG
  30 /* Debugging check only needed during development */
  31 #define ASSERT_CTXT_MAGIC(magic) do { if ((magic) != OBD_RUN_CTXT_MAGIC) { \
  32                                 CERROR("bad ctxt magic\n"); LBUG(); } } while(0)
  33 #define ASSERT_NOT_KERNEL_CTXT(msg) do { if (segment_eq(get_fs(), get_ds())) { \
  34                                         CERROR(msg); LBUG(); } } while(0)
  35 #define ASSERT_KERNEL_CTXT(msg) do { if (!segment_eq(get_fs(), get_ds())) { \
  36                                         CERROR(msg); LBUG(); } } while(0)
  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 obd_run_ctxt *save, struct obd_run_ctxt *new,
  45                struct obd_ucred *uc)
  46 {
  47         //ASSERT_NOT_KERNEL_CTXT("already in kernel context!\n");
  48         ASSERT_CTXT_MAGIC(new->magic);
  49         OBD_SET_CTXT_MAGIC(save);
  50         save->fs = get_fs();
  51         save->pwd = dget(current->fs->pwd);
  52         save->pwdmnt = mntget(current->fs->pwdmnt);
  53         save->override = cap_raised(current->cap_effective, CAP_DAC_OVERRIDE);
  54
  55         LASSERT(save->pwd);
  56         LASSERT(save->pwdmnt);
  57         LASSERT(new->pwd);
  58         LASSERT(new->pwdmnt);
  59
  60         save->fsuid = current->fsuid;
  61         save->fsgid = current->fsgid;
  62         if (uc) {
  63                 current->fsuid = uc->ouc_fsuid;
  64                 current->fsgid = uc->ouc_fsgid;
  65         }
  66         set_fs(new->fs);
  67         set_fs_pwd(current->fs, new->pwdmnt, new->pwd);
  68         if (save->override)
  69                 cap_lower(current->cap_effective, CAP_DAC_OVERRIDE);
  70 }
  71
  72 void pop_ctxt(struct obd_run_ctxt *saved)
  73 {
  74         //printk("pc0");
  75         ASSERT_CTXT_MAGIC(saved->magic);
  76         //printk("pc1");
  77         ASSERT_KERNEL_CTXT("popping non-kernel context!\n");
  78         //printk("pc2");
  79         set_fs(saved->fs);
  80         //printk("pc3\n");
  81         set_fs_pwd(current->fs, saved->pwdmnt, saved->pwd);
  82         //printk("pc4");
  83
  84         dput(saved->pwd);
  85         //printk("pc5");
  86         mntput(saved->pwdmnt);
  87         //printk("pc6\n");
  88         current->fsuid = saved->fsuid;
  89         current->fsgid = saved->fsgid;
  90
  91         if (saved->override)
  92                 cap_raise(current->cap_effective, CAP_DAC_OVERRIDE);
  93 }
  94
  95 /* utility to make a file */
  96 struct dentry *simple_mknod(struct dentry *dir, char *name, int mode)
  97 {
  98         struct dentry *dchild;
  99         int err = 0;
 100         ENTRY;
 101
 102         ASSERT_KERNEL_CTXT("kernel doing mknod outside kernel context\n");
 103         CDEBUG(D_INODE, "creating file %*s\n", (int)strlen(name), name);
 104
 105         down(&dir->d_inode->i_sem);
 106         dchild = lookup_one_len(name, dir, strlen(name));
 107         if (IS_ERR(dchild))
 108                 GOTO(out, PTR_ERR(dchild));
 109
 110         if (dchild->d_inode) {
 111                 if ((dchild->d_inode->i_mode & S_IFMT) != S_IFREG)
 112                         GOTO(out, err = -EEXIST);
 113
 114                 GOTO(out, dchild);
 115         }
 116
 117         err = vfs_create(dir->d_inode, dchild, (mode & ~S_IFMT) | S_IFREG);
 118         EXIT;
 119 out:
 120         up(&dir->d_inode->i_sem);
 121         if (err) {
 122                 dput(dchild);
 123                 RETURN(ERR_PTR(err));
 124         }
 125
 126         RETURN(dchild);
 127 }
 128
 129 /* utility to make a directory */
 130 struct dentry *simple_mkdir(struct dentry *dir, char *name, int mode)
 131 {
 132         struct dentry *dchild;
 133         int err = 0;
 134         ENTRY;
 135
 136         ASSERT_KERNEL_CTXT("kernel doing mkdir outside kernel context\n");
 137         CDEBUG(D_INODE, "creating directory %*s\n", (int)strlen(name), name);
 138         down(&dir->d_inode->i_sem);
 139         dchild = lookup_one_len(name, dir, strlen(name));
 140         if (IS_ERR(dchild))
 141                 GOTO(out, PTR_ERR(dchild));
 142
 143         if (dchild->d_inode) {
 144                 if (!S_ISDIR(dchild->d_inode->i_mode))
 145                         GOTO(out, err = -ENOTDIR);
 146
 147                 GOTO(out, dchild);
 148         }
 149
 150         err = vfs_mkdir(dir->d_inode, dchild, mode);
 151         EXIT;
 152 out:
 153         up(&dir->d_inode->i_sem);
 154         if (err) {
 155                 dput(dchild);
 156                 RETURN(ERR_PTR(err));
 157         }
 158
 159         RETURN(dchild);
 160 }
 161
 162 /*
 163  * Read a file from within kernel context.  Prior to calling this
 164  * function we should already have done a push_ctxt().
 165  */
 166 int lustre_fread(struct file *file, char *str, int len, loff_t *off)
 167 {
 168         ASSERT_KERNEL_CTXT("kernel doing read outside kernel context\n");
 169         if (!file || !file->f_op || !file->f_op->read || !off)
 170                 RETURN(-ENOSYS);
 171
 172         return file->f_op->read(file, str, len, off);
 173 }
 174
 175 /*
 176  * Write a file from within kernel context.  Prior to calling this
 177  * function we should already have done a push_ctxt().
 178  */
 179 int lustre_fwrite(struct file *file, const char *str, int len, loff_t *off)
 180 {
 181         ASSERT_KERNEL_CTXT("kernel doing write outside kernel context\n");
 182         if (!file || !file->f_op || !off)
 183                 RETURN(-ENOSYS);
 184
 185         if (!file->f_op->write)
 186                 RETURN(-EROFS);
 187
 188         return file->f_op->write(file, str, len, off);
 189 }
 190
 191 /*
 192  * Sync a file from within kernel context.  Prior to calling this
 193  * function we should already have done a push_ctxt().
 194  */
 195 int lustre_fsync(struct file *file)
 196 {
 197         ASSERT_KERNEL_CTXT("kernel doing sync outside kernel context\n");
 198         if (!file || !file->f_op || !file->f_op->fsync)
 199                 RETURN(-ENOSYS);
 200
 201         return file->f_op->fsync(file, file->f_dentry, 0);
 202 }