posix_fallocate_xfs.c

   1 /*
   2     posix_fallocate_xfs preloadable library to make posix_fallocate
   3     use XFS' more efficient preallocation using unwritten extents
   4
   5     Copyright © 2010 Bjoern JACKE <bjoern@j3e.de>
   6
   7     This program is free software: you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation, either version 3 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License
  18     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #ifndef RTLD_NEXT
  22 #  define _GNU_SOURCE
  23 #endif
  24
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27 #include <fcntl.h>
  28 #include <dlfcn.h>
  29 #include <xfs/xfs.h>
  30
  31
  32 static int (*libc_posix_fallocate)(int, off_t, off_t)= NULL;
  33
  34 static void __attribute__ ((constructor)) posix_fallocate_xfs_init(void)
  35 {
  36         libc_posix_fallocate= dlsym(RTLD_NEXT, "posix_fallocate");
  37         if (!libc_posix_fallocate || dlerror())
  38                 _exit(1);
  39 }
  40
  41 int posix_fallocate(int fd, off_t offset, off_t len)
  42 {
  43         xfs_flock64_t fl;
  44         off_t new_len = offset + len;
  45         int ret;
  46         struct stat sbuf;
  47
  48         if (new_len < 0)
  49                 return EFBIG;
  50
  51         fl.l_whence = SEEK_SET;
  52         fl.l_start = offset;
  53         fl.l_len = len;
  54
  55         ret=xfsctl(NULL, fd, XFS_IOC_RESVSP, &fl);
  56
  57         if (ret != 0)
  58                 return errno;
  59
  60
  61         /* Make sure the space shows up when we enlarged the file: */
  62         fstat(fd,&sbuf);
  63         if (new_len > sbuf.st_size) {
  64                 ftruncate(fd, new_len);
  65         }
  66         return 0;
  67 }
  68
  69 int posix_fallocate64(int fd, off64_t offset, off64_t len)
  70 {
  71         xfs_flock64_t fl;
  72         off64_t new_len = offset + len;
  73         int ret;
  74         struct stat64 sbuf;
  75
  76         fl.l_whence = SEEK_SET;
  77         fl.l_start = offset;
  78         fl.l_len = len;
  79
  80         ret=xfsctl(NULL, fd, XFS_IOC_RESVSP, &fl);
  81
  82         if (ret != 0)
  83                 return errno;
  84
  85         /* Make sure the space shows up when we enlarged the file: */
  86         fstat64(fd,&sbuf);
  87         if (new_len > sbuf.st_size) {
  88                 ftruncate64(fd, new_len);
  89         }
  90         return 0;
  91 }
  92