source3/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 #include "smbd/smbd.h"
  22
  23 /* Extent preallocation module.
  24  *
  25  * The purpose of this module is to preallocate space on the filesystem when
  26  * we have a good idea of how large files are supposed to be. This lets writes
  27  * proceed without having to allocate new extents and results in better file
  28  * layouts on disk.
  29  *
  30  * Currently only implemented for XFS. This module is based on an original idea
  31  * and implementation by Sebastian Brings.
  32  *
  33  * Tunables.
  34  *
  35  *      prealloc: <ext>     Number of bytes to preallocate for a file with
  36  *                          the matching extension.
  37  *      prealloc:debug      Debug level at which to emit messages.
  38  *
  39  * Example.
  40  *
  41  *      prealloc:mpeg = 500M  # Preallocate *.mpeg to 500 MiB.
  42  */
  43
  44 #ifdef HAVE_XFS_LIBXFS_H
  45 #include <xfs/libxfs.h>
  46 #define lock_type xfs_flock64_t
  47 #else
  48 #define lock_type struct flock64
  49 #endif
  50
  51 #ifdef HAVE_GPFS
  52 #include "gpfs_gpl.h"
  53 #endif
  54
  55 #define MODULE "prealloc"
  56 static int module_debug;
  57
  58 static int preallocate_space(int fd, SMB_OFF_T size)
  59 {
  60         int err;
  61 #ifndef HAVE_GPFS
  62         lock_type fl = {0};
  63
  64         if (size <= 0) {
  65                 return 0;
  66         }
  67
  68         fl.l_whence = SEEK_SET;
  69         fl.l_start = 0;
  70         fl.l_len = size;
  71
  72         /* IMPORTANT: We use RESVSP because we want the extents to be
  73          * allocated, but we don't want the allocation to show up in
  74          * st_size or persist after the close(2).
  75          */
  76
  77 #if defined(XFS_IOC_RESVSP64)
  78         /* On Linux this comes in via libxfs.h. */
  79         err = xfsctl(NULL, fd, XFS_IOC_RESVSP64, &fl);
  80 #elif defined(F_RESVSP64)
  81         /* On IRIX, this comes from fcntl.h. */
  82         err = fcntl(fd, F_RESVSP64, &fl);
  83 #else
  84         err = -1;
  85         errno = ENOSYS;
  86 #endif
  87 #else /* GPFS uses completely different interface */
  88        err = gpfs_prealloc(fd, (gpfs_off64_t)0, (gpfs_off64_t)size);
  89 #endif
  90
  91         if (err) {
  92                 DEBUG(module_debug,
  93                         ("%s: preallocate failed on fd=%d size=%lld: %s\n",
  94                         MODULE, fd, (long long)size, strerror(errno)));
  95         }
  96
  97         return err;
  98 }
  99
 100 static int prealloc_connect(
 101                 struct vfs_handle_struct *  handle,
 102                 const char *                service,
 103                 const char *                user)
 104 {
 105         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 106
 107         if (ret < 0) {
 108                 return ret;
 109         }
 110
 111         module_debug = lp_parm_int(SNUM(handle->conn),
 112                                         MODULE, "debug", 100);
 113
 114         return 0;
 115 }
 116
 117 static int prealloc_open(vfs_handle_struct* handle,
 118                         struct smb_filename *smb_fname,
 119                         files_struct *      fsp,
 120                         int                 flags,
 121                         mode_t              mode)
 122 {
 123         int fd;
 124         off64_t size = 0;
 125
 126         const char * dot;
 127         char fext[10];
 128
 129         if (!(flags & (O_CREAT|O_TRUNC))) {
 130                 /* Caller is not intending to rewrite the file. Let's not mess
 131                  * with the allocation in this case.
 132                  */
 133                 goto normal_open;
 134         }
 135
 136         *fext = '\0';
 137         dot = strrchr(smb_fname->base_name, '.');
 138         if (dot && *++dot) {
 139                 if (strlen(dot) < sizeof(fext)) {
 140                         strncpy(fext, dot, sizeof(fext));
 141                         strnorm(fext, CASE_LOWER);
 142                 }
 143         }
 144
 145         if (*fext == '\0') {
 146                 goto normal_open;
 147         }
 148
 149         /* Syntax for specifying preallocation size is:
 150          *      MODULE: <extension> = <size>
 151          * where
 152          *      <extension> is the file extension in lower case
 153          *      <size> is a size like 10, 10K, 10M
 154          */
 155         size = conv_str_size(lp_parm_const_string(SNUM(handle->conn), MODULE,
 156                                                     fext, NULL));
 157         if (size <= 0) {
 158                 /* No need to preallocate this file. */
 159                 goto normal_open;
 160         }
 161
 162         fd = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 163         if (fd < 0) {
 164                 return fd;
 165         }
 166
 167         /* Prellocate only if the file is being created or replaced. Note that
 168          * Samba won't ever pass down O_TRUNC, which is why we have to handle
 169          * truncate calls specially.
 170          */
 171         if ((flags & O_CREAT) || (flags & O_TRUNC)) {
 172                 SMB_OFF_T * psize;
 173
 174                 psize = VFS_ADD_FSP_EXTENSION(handle, fsp, SMB_OFF_T, NULL);
 175                 if (psize == NULL || *psize == -1) {
 176                         return fd;
 177                 }
 178
 179                 DEBUG(module_debug,
 180                         ("%s: preallocating %s (fd=%d) to %lld bytes\n",
 181                             MODULE, smb_fname_str_dbg(smb_fname), fd,
 182                             (long long)size));
 183
 184                 *psize = size;
 185                 if (preallocate_space(fd, *psize) < 0) {
 186                         VFS_REMOVE_FSP_EXTENSION(handle, fsp);
 187                 }
 188         }
 189
 190         return fd;
 191
 192 normal_open:
 193         /* We are not creating or replacing a file. Skip the
 194          * preallocation.
 195          */
 196         DEBUG(module_debug, ("%s: skipping preallocation for %s\n",
 197                 MODULE, smb_fname_str_dbg(smb_fname)));
 198         return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 199 }
 200
 201 static int prealloc_ftruncate(vfs_handle_struct * handle,
 202                         files_struct *  fsp,
 203                         SMB_OFF_T       offset)
 204 {
 205         SMB_OFF_T *psize;
 206         int ret = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, offset);
 207
 208         /* Maintain the allocated space even in the face of truncates. */
 209         if ((psize = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
 210                 preallocate_space(fsp->fh->fd, *psize);
 211         }
 212
 213         return ret;
 214 }
 215
 216 static struct vfs_fn_pointers prealloc_fns = {
 217         .open_fn = prealloc_open,
 218         .ftruncate = prealloc_ftruncate,
 219         .connect_fn = prealloc_connect,
 220 };
 221
 222 NTSTATUS vfs_prealloc_init(void);
 223 NTSTATUS vfs_prealloc_init(void)
 224 {
 225         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 226                                 MODULE, &prealloc_fns);
 227 }