arch/um/drivers/ubd_user.c

   1 /*
   2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Copyright (C) 2001 Ridgerun,Inc (glonnon@ridgerun.com)
   4  * Licensed under the GPL
   5  */
   6
   7 #include <stddef.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <sched.h>
  11 #include <signal.h>
  12 #include <string.h>
  13 #include <netinet/in.h>
  14 #include <sys/time.h>
  15 #include <sys/socket.h>
  16 #include <sys/mman.h>
  17 #include <sys/param.h>
  18 #include "asm/types.h"
  19 #include "user_util.h"
  20 #include "kern_util.h"
  21 #include "user.h"
  22 #include "ubd_user.h"
  23 #include "os.h"
  24 #include "cow.h"
  25
  26 #include <endian.h>
  27 #include <byteswap.h>
  28
  29 static int same_backing_files(char *from_cmdline, char *from_cow, char *cow)
  30 {
  31         struct uml_stat buf1, buf2;
  32         int err;
  33
  34         if(from_cmdline == NULL) return(1);
  35         if(!strcmp(from_cmdline, from_cow)) return(1);
  36
  37         err = os_stat_file(from_cmdline, &buf1);
  38         if(err < 0){
  39                 printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
  40                 return(1);
  41         }
  42         err = os_stat_file(from_cow, &buf2);
  43         if(err < 0){
  44                 printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
  45                 return(1);
  46         }
  47         if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
  48                 return(1);
  49
  50         printk("Backing file mismatch - \"%s\" requested,\n"
  51                "\"%s\" specified in COW header of \"%s\"\n",
  52                from_cmdline, from_cow, cow);
  53         return(0);
  54 }
  55
  56 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
  57 {
  58         unsigned long modtime;
  59         long long actual;
  60         int err;
  61
  62         err = os_file_modtime(file, &modtime);
  63         if(err < 0){
  64                 printk("Failed to get modification time of backing file "
  65                        "\"%s\", err = %d\n", file, -err);
  66                 return(err);
  67         }
  68
  69         err = os_file_size(file, &actual);
  70         if(err < 0){
  71                 printk("Failed to get size of backing file \"%s\", "
  72                        "err = %d\n", file, -err);
  73                 return(err);
  74         }
  75
  76         if(actual != size){
  77                 printk("Size mismatch (%ld vs %ld) of COW header vs backing "
  78                        "file\n", size, actual);
  79                 return(-EINVAL);
  80         }
  81         if(modtime != mtime){
  82                 printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
  83                        "file\n", mtime, modtime);
  84                 return(-EINVAL);
  85         }
  86         return(0);
  87 }
  88
  89 int read_cow_bitmap(int fd, void *buf, int offset, int len)
  90 {
  91         int err;
  92
  93         err = os_seek_file(fd, offset);
  94         if(err < 0)
  95                 return(err);
  96
  97         err = os_read_file(fd, buf, len);
  98         if(err < 0)
  99                 return(err);
 100
 101         return(0);
 102 }
 103
 104 int open_ubd_file(char *file, struct openflags *openflags,
 105                   char **backing_file_out, int *bitmap_offset_out,
 106                   unsigned long *bitmap_len_out, int *data_offset_out,
 107                   int *create_cow_out)
 108 {
 109         time_t mtime;
 110         __u64 size;
 111         __u32 version, align;
 112         char *backing_file;
 113         int fd, err, sectorsize, same, mode = 0644;
 114
 115         fd = os_open_file(file, *openflags, mode);
 116         if(fd < 0){
 117                 if((fd == -ENOENT) && (create_cow_out != NULL))
 118                         *create_cow_out = 1;
 119                 if(!openflags->w ||
 120                    ((errno != EROFS) && (errno != EACCES))) return(-errno);
 121                 openflags->w = 0;
 122                 fd = os_open_file(file, *openflags, mode);
 123                 if(fd < 0)
 124                         return(fd);
 125         }
 126
 127         err = os_lock_file(fd, openflags->w);
 128         if(err < 0){
 129                 printk("Failed to lock '%s', err = %d\n", file, -err);
 130                 goto out_close;
 131         }
 132
 133         if(backing_file_out == NULL) return(fd);
 134
 135         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
 136                               &size, &sectorsize, &align, bitmap_offset_out);
 137         if(err && (*backing_file_out != NULL)){
 138                 printk("Failed to read COW header from COW file \"%s\", "
 139                        "errno = %d\n", file, -err);
 140                 goto out_close;
 141         }
 142         if(err) return(fd);
 143
 144         if(backing_file_out == NULL) return(fd);
 145
 146         same = same_backing_files(*backing_file_out, backing_file, file);
 147
 148         if(!same && !backing_file_mismatch(*backing_file_out, size, mtime)){
 149                 printk("Switching backing file to '%s'\n", *backing_file_out);
 150                 err = write_cow_header(file, fd, *backing_file_out,
 151                                        sectorsize, align, &size);
 152                 if(err){
 153                         printk("Switch failed, errno = %d\n", -err);
 154                         return(err);
 155                 }
 156         }
 157         else {
 158                 *backing_file_out = backing_file;
 159                 err = backing_file_mismatch(*backing_file_out, size, mtime);
 160                 if(err) goto out_close;
 161         }
 162
 163         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
 164                   bitmap_len_out, data_offset_out);
 165
 166         return(fd);
 167  out_close:
 168         os_close_file(fd);
 169         return(err);
 170 }
 171
 172 int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
 173                     int sectorsize, int alignment, int *bitmap_offset_out,
 174                     unsigned long *bitmap_len_out, int *data_offset_out)
 175 {
 176         int err, fd;
 177
 178         flags.c = 1;
 179         fd = open_ubd_file(cow_file, &flags, NULL, NULL, NULL, NULL, NULL);
 180         if(fd < 0){
 181                 err = fd;
 182                 printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
 183                        -err);
 184                 goto out;
 185         }
 186
 187         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
 188                             bitmap_offset_out, bitmap_len_out,
 189                             data_offset_out);
 190         if(!err)
 191                 return(fd);
 192         os_close_file(fd);
 193  out:
 194         return(err);
 195 }
 196
 197 /* XXX Just trivial wrappers around os_read_file and os_write_file */
 198 int read_ubd_fs(int fd, void *buffer, int len)
 199 {
 200         return(os_read_file(fd, buffer, len));
 201 }
 202
 203 int write_ubd_fs(int fd, char *buffer, int len)
 204 {
 205         return(os_write_file(fd, buffer, len));
 206 }
 207
 208 static int update_bitmap(struct io_thread_req *req)
 209 {
 210         int n;
 211
 212         if(req->cow_offset == -1)
 213                 return(0);
 214
 215         n = os_seek_file(req->fds[1], req->cow_offset);
 216         if(n < 0){
 217                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
 218                 return(1);
 219         }
 220
 221         n = os_write_file(req->fds[1], &req->bitmap_words,
 222                           sizeof(req->bitmap_words));
 223         if(n != sizeof(req->bitmap_words)){
 224                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
 225                        req->fds[1]);
 226                 return(1);
 227         }
 228
 229         return(0);
 230 }
 231
 232 void do_io(struct io_thread_req *req)
 233 {
 234         char *buf;
 235         unsigned long len;
 236         int n, nsectors, start, end, bit;
 237         int err;
 238         __u64 off;
 239
 240         if(req->op == UBD_MMAP){
 241                 /* Touch the page to force the host to do any necessary IO to
 242                  * get it into memory
 243                  */
 244                 n = *((volatile int *) req->buffer);
 245                 req->error = update_bitmap(req);
 246                 return;
 247         }
 248
 249         nsectors = req->length / req->sectorsize;
 250         start = 0;
 251         do {
 252                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
 253                 end = start;
 254                 while((end < nsectors) &&
 255                       (ubd_test_bit(end, (unsigned char *)
 256                                     &req->sector_mask) == bit))
 257                         end++;
 258
 259                 off = req->offset + req->offsets[bit] +
 260                         start * req->sectorsize;
 261                 len = (end - start) * req->sectorsize;
 262                 buf = &req->buffer[start * req->sectorsize];
 263
 264                 err = os_seek_file(req->fds[bit], off);
 265                 if(err < 0){
 266                         printk("do_io - lseek failed : err = %d\n", -err);
 267                         req->error = 1;
 268                         return;
 269                 }
 270                 if(req->op == UBD_READ){
 271                         n = 0;
 272                         do {
 273                                 buf = &buf[n];
 274                                 len -= n;
 275                                 n = os_read_file(req->fds[bit], buf, len);
 276                                 if (n < 0) {
 277                                         printk("do_io - read failed, err = %d "
 278                                                "fd = %d\n", -n, req->fds[bit]);
 279                                         req->error = 1;
 280                                         return;
 281                                 }
 282                         } while((n < len) && (n != 0));
 283                         if (n < len) memset(&buf[n], 0, len - n);
 284                 }
 285                 else {
 286                         n = os_write_file(req->fds[bit], buf, len);
 287                         if(n != len){
 288                                 printk("do_io - write failed err = %d "
 289                                        "fd = %d\n", -n, req->fds[bit]);
 290                                 req->error = 1;
 291                                 return;
 292                         }
 293                 }
 294
 295                 start = end;
 296         } while(start < nsectors);
 297
 298         req->error = update_bitmap(req);
 299 }
 300
 301 /* Changed in start_io_thread, which is serialized by being called only
 302  * from ubd_init, which is an initcall.
 303  */
 304 int kernel_fd = -1;
 305
 306 /* Only changed by the io thread */
 307 int io_count = 0;
 308
 309 int io_thread(void *arg)
 310 {
 311         struct io_thread_req req;
 312         int n;
 313
 314         signal(SIGWINCH, SIG_IGN);
 315         while(1){
 316                 n = os_read_file(kernel_fd, &req, sizeof(req));
 317                 if(n != sizeof(req)){
 318                         if(n < 0)
 319                                 printk("io_thread - read failed, fd = %d, "
 320                                        "err = %d\n", kernel_fd, -n);
 321                         else {
 322                                 printk("io_thread - short read, fd = %d, "
 323                                        "length = %d\n", kernel_fd, n);
 324                         }
 325                         continue;
 326                 }
 327                 io_count++;
 328                 do_io(&req);
 329                 n = os_write_file(kernel_fd, &req, sizeof(req));
 330                 if(n != sizeof(req))
 331                         printk("io_thread - write failed, fd = %d, err = %d\n",
 332                                kernel_fd, -n);
 333         }
 334 }
 335
 336 int start_io_thread(unsigned long sp, int *fd_out)
 337 {
 338         int pid, fds[2], err;
 339
 340         err = os_pipe(fds, 1, 1);
 341         if(err < 0){
 342                 printk("start_io_thread - os_pipe failed, err = %d\n", -err);
 343                 goto out;
 344         }
 345
 346         kernel_fd = fds[0];
 347         *fd_out = fds[1];
 348
 349         pid = clone(io_thread, (void *) sp, CLONE_FILES | CLONE_VM | SIGCHLD,
 350                     NULL);
 351         if(pid < 0){
 352                 printk("start_io_thread - clone failed : errno = %d\n", errno);
 353                 err = -errno;
 354                 goto out_close;
 355         }
 356
 357         return(pid);
 358
 359  out_close:
 360         os_close_file(fds[0]);
 361         os_close_file(fds[1]);
 362         kernel_fd = -1;
 363         *fd_out = -1;
 364  out:
 365         return(err);
 366 }
 367
 368 /*
 369  * Overrides for Emacs so that we follow Linus's tabbing style.
 370  * Emacs will notice this stuff at the end of the file and automatically
 371  * adjust the settings for this buffer only.  This must remain at the end
 372  * of the file.
 373  * ---------------------------------------------------------------------------
 374  * Local variables:
 375  * c-file-style: "linux"
 376  * End:
 377  */