source/modules/vfs_prealloc.c

   1 /*
   2  * XFS preallocation support module.
   3  *
   4  * Copyright (c) James Peach 2006
   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 as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "includes.h"
  21
  22 /* Extent preallocation module.
  23  *
  24  * The purpose of this module is to preallocate space on the filesystem when
  25  * we have a good idea of how large files are supposed to be. This lets writes
  26  * proceed without having to allocate new extents and results in better file
  27  * layouts on disk.
  28  *
  29  * Currently only implemented for XFS. This module is based on an original idea
  30  * and implementation by Sebastian Brings.
  31  *
  32  * Tunables.
  33  *
  34  *      prealloc: <ext>     Number of bytes to preallocate for a file with
  35  *                          the matching extension.
  36  *      prealloc:debug      Debug level at which to emit messages.
  37  *
  38  * Example.
  39  *
  40  *      prealloc:mpeg = 500M  # Preallocate *.mpeg to 500 MiB.
  41  */
  42
  43 #ifdef HAVE_XFS_LIBXFS_H
  44 #include <xfs/libxfs.h>
  45 #define lock_type xfs_flock64_t
  46 #else
  47 #define lock_type struct flock64
  48 #endif
  49
  50 #ifdef HAVE_GPFS
  51 #include "gpfs_gpl.h"
  52 #endif
  53
  54 #define MODULE "prealloc"
  55 static int module_debug;
  56
  57 static int preallocate_space(int fd, SMB_OFF_T size)
  58 {
  59         int err;
  60 #ifndef HAVE_GPFS
  61         lock_type fl = {0};
  62
  63         if (size <= 0) {
  64                 return 0;
  65         }
  66
  67         fl.l_whence = SEEK_SET;
  68         fl.l_start = 0;
  69         fl.l_len = size;
  70
  71         /* IMPORTANT: We use RESVSP because we want the extents to be
  72          * allocated, but we don't want the allocation to show up in
  73          * st_size or persist after the close(2).
  74          */
  75
  76 #if defined(XFS_IOC_RESVSP64)
  77         /* On Linux this comes in via libxfs.h. */
  78         err = xfsctl(NULL, fd, XFS_IOC_RESVSP64, &fl);
  79 #elif defined(F_RESVSP64)
  80         /* On IRIX, this comes from fcntl.h. */
  81         err = fcntl(fd, F_RESVSP64, &fl);
  82 #else
  83         err = -1;
  84         errno = ENOSYS;
  85 #endif
  86 #else /* GPFS uses completely different interface */
  87        err = gpfs_prealloc(fd, (gpfs_off64_t)0, (gpfs_off64_t)size);
  88 #endif
  89
  90         if (err) {
  91                 DEBUG(module_debug,
  92                         ("%s: preallocate failed on fd=%d size=%lld: %s\n",
  93                         MODULE, fd, (long long)size, strerror(errno)));
  94         }
  95
  96         return err;
  97 }
  98
  99 static int prealloc_connect(
 100                 struct vfs_handle_struct *  handle,
 101                 const char *                service,
 102                 const char *                user)
 103 {
 104             module_debug = lp_parm_int(SNUM(handle->conn),
 105                                         MODULE, "debug", 100);
 106
 107             return SMB_VFS_NEXT_CONNECT(handle, service, user);
 108 }
 109
 110 static int prealloc_open(vfs_handle_struct* handle,
 111                         const char *        fname,
 112                         files_struct *      fsp,
 113                         int                 flags,
 114                         mode_t              mode)
 115 {
 116         int fd;
 117         off64_t size = 0;
 118
 119         const char * dot;
 120         char fext[10];
 121
 122         if (!(flags & (O_CREAT|O_TRUNC))) {
 123                 /* Caller is not intending to rewrite the file. Let's not mess
 124                  * with the allocation in this case.
 125                  */
 126                 goto normal_open;
 127         }
 128
 129         *fext = '\0';
 130         dot = strrchr(fname, '.');
 131         if (dot && *++dot) {
 132                 if (strlen(dot) < sizeof(fext)) {
 133                         strncpy(fext, dot, sizeof(fext));
 134                         strnorm(fext, CASE_LOWER);
 135                 }
 136         }
 137
 138         if (*fext == '\0') {
 139                 goto normal_open;
 140         }
 141
 142         /* Syntax for specifying preallocation size is:
 143          *      MODULE: <extension> = <size>
 144          * where
 145          *      <extension> is the file extension in lower case
 146          *      <size> is a size like 10, 10K, 10M
 147          */
 148         size = conv_str_size(lp_parm_const_string(SNUM(handle->conn), MODULE,
 149                                                     fext, NULL));
 150         if (size <= 0) {
 151                 /* No need to preallocate this file. */
 152                 goto normal_open;
 153         }
 154
 155         fd = SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
 156         if (fd < 0) {
 157                 return fd;
 158         }
 159
 160         /* Prellocate only if the file is being created or replaced. Note that
 161          * Samba won't ever pass down O_TRUNC, which is why we have to handle
 162          * truncate calls specially.
 163          */
 164         if ((flags & O_CREAT) || (flags & O_TRUNC)) {
 165                 SMB_OFF_T * psize;
 166
 167                 psize = VFS_ADD_FSP_EXTENSION(handle, fsp, SMB_OFF_T);
 168                 if (psize == NULL || *psize == -1) {
 169                         return fd;
 170                 }
 171
 172                 DEBUG(module_debug,
 173                         ("%s: preallocating %s (fd=%d) to %lld bytes\n",
 174                         MODULE, fname, fd, (long long)size));
 175
 176                 *psize = size;
 177                 if (preallocate_space(fd, *psize) < 0) {
 178                         VFS_REMOVE_FSP_EXTENSION(handle, fsp);
 179                 }
 180         }
 181
 182         return fd;
 183
 184 normal_open:
 185         /* We are not creating or replacing a file. Skip the
 186          * preallocation.
 187          */
 188         DEBUG(module_debug, ("%s: skipping preallocation for %s\n",
 189                     MODULE, fname));
 190         return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
 191 }
 192
 193 static int prealloc_ftruncate(vfs_handle_struct * handle,
 194                         files_struct *  fsp,
 195                         SMB_OFF_T       offset)
 196 {
 197         SMB_OFF_T *psize;
 198         int ret = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, offset);
 199
 200         /* Maintain the allocated space even in the face of truncates. */
 201         if ((psize = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
 202                 preallocate_space(fsp->fh->fd, *psize);
 203         }
 204
 205         return ret;
 206 }
 207
 208 static vfs_op_tuple prealloc_op_tuples[] = {
 209         {SMB_VFS_OP(prealloc_open), SMB_VFS_OP_OPEN, SMB_VFS_LAYER_TRANSPARENT},
 210         {SMB_VFS_OP(prealloc_ftruncate), SMB_VFS_OP_FTRUNCATE, SMB_VFS_LAYER_TRANSPARENT},
 211         {SMB_VFS_OP(prealloc_connect), SMB_VFS_OP_CONNECT, SMB_VFS_LAYER_TRANSPARENT},
 212         {NULL,  SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 213 };
 214
 215 NTSTATUS vfs_prealloc_init(void);
 216 NTSTATUS vfs_prealloc_init(void)
 217 {
 218         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 219                 MODULE, prealloc_op_tuples);
 220 }