sys-utils/fallocate.c

   1 /*
   2  * fallocate - utility to use the fallocate system call
   3  *
   4  * Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
   5  * Written by Eric Sandeen <sandeen@redhat.com>
   6  *            Karel Zak <kzak@redhat.com>
   7  *
   8  * cvtnum routine taken from xfsprogs,
   9  * Copyright (c) 2003-2005 Silicon Graphics, Inc.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License as
  13  * published by the Free Software Foundation.
  14  *
  15  * This program is distributed in the hope that it would be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License along
  21  * with this program; if not, write to the Free Software Foundation, Inc.,
  22  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24 #include <sys/stat.h>
  25 #include <sys/types.h>
  26 #include <sys/mman.h>
  27 #include <ctype.h>
  28 #include <errno.h>
  29 #include <fcntl.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <unistd.h>
  33 #include <getopt.h>
  34 #include <limits.h>
  35 #include <string.h>
  36
  37 #ifndef HAVE_FALLOCATE
  38 # include <sys/syscall.h>
  39 #endif
  40
  41 #if defined(HAVE_LINUX_FALLOC_H) && \
  42     (!defined(FALLOC_FL_KEEP_SIZE) || !defined(FALLOC_FL_PUNCH_HOLE) || \
  43      !defined(FALLOC_FL_COLLAPSE_RANGE) || !defined(FALLOC_FL_ZERO_RANGE) || \
  44      !defined(FALLOC_FL_INSERT_RANGE))
  45 # include <linux/falloc.h>      /* non-libc fallback for FALLOC_FL_* flags */
  46 #endif
  47
  48
  49 #ifndef FALLOC_FL_KEEP_SIZE
  50 # define FALLOC_FL_KEEP_SIZE            0x1
  51 #endif
  52
  53 #ifndef FALLOC_FL_PUNCH_HOLE
  54 # define FALLOC_FL_PUNCH_HOLE           0x2
  55 #endif
  56
  57 #ifndef FALLOC_FL_COLLAPSE_RANGE
  58 # define FALLOC_FL_COLLAPSE_RANGE       0x8
  59 #endif
  60
  61 #ifndef FALLOC_FL_ZERO_RANGE
  62 # define FALLOC_FL_ZERO_RANGE           0x10
  63 #endif
  64
  65 #ifndef FALLOC_FL_INSERT_RANGE
  66 # define FALLOC_FL_INSERT_RANGE         0x20
  67 #endif
  68
  69 #include "nls.h"
  70 #include "strutils.h"
  71 #include "c.h"
  72 #include "closestream.h"
  73 #include "xalloc.h"
  74 #include "optutils.h"
  75
  76 static int verbose;
  77 static char *filename;
  78
  79 static void __attribute__((__noreturn__)) usage(FILE *out)
  80 {
  81         fputs(USAGE_HEADER, out);
  82         fprintf(out,
  83               _(" %s [options] <filename>\n"), program_invocation_short_name);
  84
  85         fputs(USAGE_SEPARATOR, out);
  86         fputs(_("Preallocate space to, or deallocate space from a file.\n"), out);
  87
  88         fputs(USAGE_OPTIONS, out);
  89         fputs(_(" -c, --collapse-range remove a range from the file\n"), out);
  90         fputs(_(" -d, --dig-holes      detect zeroes and replace with holes\n"), out);
  91         fputs(_(" -i, --insert-range   insert a hole at range, shifting existing data\n"), out);
  92         fputs(_(" -l, --length <num>   length for range operations, in bytes\n"), out);
  93         fputs(_(" -n, --keep-size      maintain the apparent size of the file\n"), out);
  94         fputs(_(" -o, --offset <num>   offset for range operations, in bytes\n"), out);
  95         fputs(_(" -p, --punch-hole     replace a range with a hole (implies -n)\n"), out);
  96         fputs(_(" -z, --zero-range     zero and ensure allocation of a range\n"), out);
  97 #ifdef HAVE_POSIX_FALLOCATE
  98         fputs(_(" -x, --posix          use posix_fallocate(3) instead of fallocate(2)\n"), out);
  99 #endif
 100         fputs(_(" -v, --verbose        verbose mode\n"), out);
 101
 102         fputs(USAGE_SEPARATOR, out);
 103         fputs(USAGE_HELP, out);
 104         fputs(USAGE_VERSION, out);
 105
 106         fprintf(out, USAGE_MAN_TAIL("fallocate(1)"));
 107
 108         exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 109 }
 110
 111 static loff_t cvtnum(char *s)
 112 {
 113         uintmax_t x;
 114
 115         if (strtosize(s, &x))
 116                 return -1LL;
 117
 118         return x;
 119 }
 120
 121 static void xfallocate(int fd, int mode, off_t offset, off_t length)
 122 {
 123         int error;
 124 #ifdef HAVE_FALLOCATE
 125         error = fallocate(fd, mode, offset, length);
 126 #else
 127         error = syscall(SYS_fallocate, fd, mode, offset, length);
 128 #endif
 129         /*
 130          * EOPNOTSUPP: The FALLOC_FL_KEEP_SIZE is unsupported
 131          * ENOSYS: The filesystem does not support sys_fallocate
 132          */
 133         if (error < 0) {
 134                 if ((mode & FALLOC_FL_KEEP_SIZE) && errno == EOPNOTSUPP)
 135                         errx(EXIT_FAILURE, _("fallocate failed: keep size mode is unsupported"));
 136                 err(EXIT_FAILURE, _("fallocate failed"));
 137         }
 138 }
 139
 140 #ifdef HAVE_POSIX_FALLOCATE
 141 static void xposix_fallocate(int fd, off_t offset, off_t length)
 142 {
 143         int error = posix_fallocate(fd, offset, length);
 144         if (error < 0) {
 145                 err(EXIT_FAILURE, _("fallocate failed"));
 146         }
 147 }
 148 #endif
 149
 150 static int skip_hole(int fd, off_t *off)
 151 {
 152         off_t newoff;
 153
 154         errno = 0;
 155         newoff  = lseek(fd, *off, SEEK_DATA);
 156
 157         /* ENXIO means that there is no more data -- probably sparse hole at
 158          * the end of the file */
 159         if (newoff < 0 && errno == ENXIO)
 160                 return 1;
 161
 162         if (newoff > *off) {
 163                 *off = newoff;
 164                 return 0;       /* success */
 165         }
 166         return -1;              /* no hole */
 167 }
 168
 169 /* The real buffer size has to be bufsize + sizeof(uintptr_t) */
 170 static int is_nul(void *buf, size_t bufsize)
 171 {
 172         typedef uintptr_t word;
 173         void const *vp;
 174         char const *cbuf = buf, *cp;
 175         word const *wp = buf;
 176
 177         /* set sentinel */
 178         memset((char *) buf + bufsize, '\1', sizeof(word));
 179
 180         /* Find first nonzero *word*, or the word with the sentinel.  */
 181         while (*wp++ == 0)
 182                 continue;
 183
 184         /* Find the first nonzero *byte*, or the sentinel.  */
 185         vp = wp - 1;
 186         cp = vp;
 187
 188         while (*cp++ == 0)
 189                 continue;
 190
 191         return cbuf + bufsize < cp;
 192 }
 193
 194 static void dig_holes(int fd, off_t off, off_t len)
 195 {
 196         off_t end = len ? off + len : 0;
 197         off_t hole_start = 0, hole_sz = 0;
 198         uintmax_t ct = 0;
 199         size_t  bufsz;
 200         char *buf;
 201         struct stat st;
 202 #if defined(POSIX_FADV_SEQUENTIAL) && defined(HAVE_POSIX_FADVISE)
 203         off_t cache_start = off;
 204         /*
 205          * We don't want to call POSIX_FADV_DONTNEED to discard cached
 206          * data in PAGE_SIZE steps. IMHO it's overkill (too many syscalls).
 207          *
 208          * Let's assume that 1MiB (on system with 4K page size) is just
 209          * a good compromise.
 210          *                                          -- kzak Feb-2014
 211          */
 212         const size_t cachesz = getpagesize() * 256;
 213 #endif
 214
 215         if (fstat(fd, &st) != 0)
 216                 err(EXIT_FAILURE, _("stat of %s failed"), filename);
 217
 218         bufsz = st.st_blksize;
 219
 220         if (lseek(fd, off, SEEK_SET) < 0)
 221                 err(EXIT_FAILURE, _("seek on %s failed"), filename);
 222
 223         /* buffer + extra space for is_nul() sentinel */
 224         buf = xmalloc(bufsz + sizeof(uintptr_t));
 225 #if defined(POSIX_FADV_SEQUENTIAL) && defined(HAVE_POSIX_FADVISE)
 226         posix_fadvise(fd, off, 0, POSIX_FADV_SEQUENTIAL);
 227 #endif
 228
 229         while (end == 0 || off < end) {
 230                 ssize_t rsz;
 231
 232                 rsz = pread(fd, buf, bufsz, off);
 233                 if (rsz < 0 && errno)
 234                         err(EXIT_FAILURE, _("%s: read failed"), filename);
 235                 if (end && rsz > 0 && off > end - rsz)
 236                         rsz = end - off;
 237                 if (rsz <= 0)
 238                         break;
 239
 240                 if (is_nul(buf, rsz)) {
 241                         if (!hole_sz) {                         /* new hole detected */
 242                                 int rc = skip_hole(fd, &off);
 243                                 if (rc == 0)
 244                                         continue;       /* hole skipped */
 245                                 else if (rc == 1)
 246                                         break;          /* end of file */
 247                                 hole_start = off;
 248                         }
 249                         hole_sz += rsz;
 250                  } else if (hole_sz) {
 251                         xfallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,
 252                                    hole_start, hole_sz);
 253                         ct += hole_sz;
 254                         hole_sz = hole_start = 0;
 255                 }
 256
 257 #if defined(POSIX_FADV_DONTNEED) && defined(HAVE_POSIX_FADVISE)
 258                 /* discard cached data */
 259                 if (off - cache_start > (off_t) cachesz) {
 260                         size_t clen = off - cache_start;
 261
 262                         clen = (clen / cachesz) * cachesz;
 263                         posix_fadvise(fd, cache_start, clen, POSIX_FADV_DONTNEED);
 264                         cache_start = cache_start + clen;
 265                 }
 266 #endif
 267                 off += rsz;
 268         }
 269
 270         if (hole_sz) {
 271                 xfallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,
 272                                 hole_start, hole_sz);
 273                 ct += hole_sz;
 274         }
 275
 276         free(buf);
 277
 278         if (verbose) {
 279                 char *str = size_to_human_string(SIZE_SUFFIX_3LETTER | SIZE_SUFFIX_SPACE, ct);
 280                 fprintf(stdout, _("%s: %s (%ju bytes) converted to sparse holes.\n"),
 281                                 filename, str, ct);
 282                 free(str);
 283         }
 284 }
 285
 286 int main(int argc, char **argv)
 287 {
 288         int     c;
 289         int     fd;
 290         int     mode = 0;
 291         int     dig = 0;
 292         int posix = 0;
 293         loff_t  length = -2LL;
 294         loff_t  offset = 0;
 295
 296         static const struct option longopts[] = {
 297             { "help",           0, 0, 'h' },
 298             { "version",        0, 0, 'V' },
 299             { "keep-size",      0, 0, 'n' },
 300             { "punch-hole",     0, 0, 'p' },
 301             { "collapse-range", 0, 0, 'c' },
 302             { "dig-holes",      0, 0, 'd' },
 303             { "insert-range",   0, 0, 'i' },
 304             { "zero-range",     0, 0, 'z' },
 305             { "offset",         1, 0, 'o' },
 306             { "length",         1, 0, 'l' },
 307             { "posix",          0, 0, 'x' },
 308             { "verbose",        0, 0, 'v' },
 309             { NULL,             0, 0, 0 }
 310         };
 311
 312         static const ul_excl_t excl[] = {       /* rows and cols in ASCII order */
 313                 { 'c', 'd', 'p', 'z' },
 314                 { 'c', 'n' },
 315                 { 'x', 'c', 'd', 'i', 'n', 'p', 'z'},
 316                 { 0 }
 317         };
 318         int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
 319
 320         setlocale(LC_ALL, "");
 321         bindtextdomain(PACKAGE, LOCALEDIR);
 322         textdomain(PACKAGE);
 323         atexit(close_stdout);
 324
 325         while ((c = getopt_long(argc, argv, "hvVncpdizxl:o:", longopts, NULL))
 326                         != -1) {
 327
 328                 err_exclusive_options(c, longopts, excl, excl_st);
 329
 330                 switch(c) {
 331                 case 'h':
 332                         usage(stdout);
 333                         break;
 334                 case 'c':
 335                         mode |= FALLOC_FL_COLLAPSE_RANGE;
 336                         break;
 337                 case 'd':
 338                         dig = 1;
 339                         break;
 340                 case 'i':
 341                         mode |= FALLOC_FL_INSERT_RANGE;
 342                         break;
 343                 case 'l':
 344                         length = cvtnum(optarg);
 345                         break;
 346                 case 'n':
 347                         mode |= FALLOC_FL_KEEP_SIZE;
 348                         break;
 349                 case 'o':
 350                         offset = cvtnum(optarg);
 351                         break;
 352                 case 'p':
 353                         mode |= FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
 354                         break;
 355                 case 'z':
 356                         mode |= FALLOC_FL_ZERO_RANGE;
 357                         break;
 358                 case 'x':
 359 #ifdef HAVE_POSIX_FALLOCATE
 360                         posix = 1;
 361                         break;
 362 #else
 363                         errx(EXIT_FAILURE, _("posix_fallocate support is not compiled"))
 364 #endif
 365                 case 'v':
 366                         verbose++;
 367                         break;
 368                 case 'V':
 369                         printf(UTIL_LINUX_VERSION);
 370                         return EXIT_SUCCESS;
 371                 default:
 372                         errtryhelp(EXIT_FAILURE);
 373                 }
 374         }
 375
 376         if (optind == argc)
 377                 errx(EXIT_FAILURE, _("no filename specified"));
 378
 379         filename = argv[optind++];
 380
 381         if (optind != argc)
 382                 errx(EXIT_FAILURE, _("unexpected number of arguments"));
 383
 384         if (dig) {
 385                 /* for --dig-holes the default is analyze all file */
 386                 if (length == -2LL)
 387                         length = 0;
 388                 if (length < 0)
 389                         errx(EXIT_FAILURE, _("invalid length value specified"));
 390         } else {
 391                 /* it's safer to require the range specification (--length --offset) */
 392                 if (length == -2LL)
 393                         errx(EXIT_FAILURE, _("no length argument specified"));
 394                 if (length <= 0)
 395                         errx(EXIT_FAILURE, _("invalid length value specified"));
 396         }
 397         if (offset < 0)
 398                 errx(EXIT_FAILURE, _("invalid offset value specified"));
 399
 400         /* O_CREAT makes sense only for the default fallocate(2) behavior
 401          * when mode is no specified and new space is allocated */
 402         fd = open(filename, O_RDWR | (!dig && !mode ? O_CREAT : 0),
 403                   S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
 404         if (fd < 0)
 405                 err(EXIT_FAILURE, _("cannot open %s"), filename);
 406
 407         if (dig)
 408                 dig_holes(fd, offset, length);
 409 #ifdef HAVE_POSIX_FALLOCATE
 410         else if (posix)
 411                 xposix_fallocate(fd, offset, length);
 412 #endif
 413         else
 414                 xfallocate(fd, mode, offset, length);
 415
 416         if (close_fd(fd) != 0)
 417                 err(EXIT_FAILURE, _("write failed: %s"), filename);
 418
 419         return EXIT_SUCCESS;
 420 }