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 "system/filesys.h"
  22 #include "smbd/smbd.h"
  23
  24 /* Extent preallocation module.
  25  *
  26  * The purpose of this module is to preallocate space on the filesystem when
  27  * we have a good idea of how large files are supposed to be. This lets writes
  28  * proceed without having to allocate new extents and results in better file
  29  * layouts on disk.
  30  *
  31  * Currently only implemented for XFS. This module is based on an original idea
  32  * and implementation by Sebastian Brings.
  33  *
  34  * Tunables.
  35  *
  36  *      prealloc: <ext>     Number of bytes to preallocate for a file with
  37  *                          the matching extension.
  38  *      prealloc:debug      Debug level at which to emit messages.
  39  *
  40  * Example.
  41  *
  42  *      prealloc:mpeg = 500M  # Preallocate *.mpeg to 500 MiB.
  43  */
  44
  45 #ifdef HAVE_XFS_LIBXFS_H
  46 #include <xfs/libxfs.h>
  47 #define lock_type xfs_flock64_t
  48 #else
  49 #define lock_type struct flock64
  50 #endif
  51
  52 #ifdef HAVE_GPFS
  53 #include "gpfs_gpl.h"
  54 #endif
  55
  56 #define MODULE "prealloc"
  57 static int module_debug;
  58
  59 static int preallocate_space(int fd, off_t size)
  60 {
  61         int err;
  62 #ifndef HAVE_GPFS
  63         lock_type fl = {0};
  64
  65         if (size <= 0) {
  66                 return 0;
  67         }
  68
  69         fl.l_whence = SEEK_SET;
  70         fl.l_start = 0;
  71         fl.l_len = size;
  72
  73         /* IMPORTANT: We use RESVSP because we want the extents to be
  74          * allocated, but we don't want the allocation to show up in
  75          * st_size or persist after the close(2).
  76          */
  77
  78 #if defined(XFS_IOC_RESVSP64)
  79         /* On Linux this comes in via libxfs.h. */
  80         err = xfsctl(NULL, fd, XFS_IOC_RESVSP64, &fl);
  81 #elif defined(F_RESVSP64)
  82         /* On IRIX, this comes from fcntl.h. */
  83         err = fcntl(fd, F_RESVSP64, &fl);
  84 #else
  85         err = -1;
  86         errno = ENOSYS;
  87 #endif
  88 #else /* GPFS uses completely different interface */
  89        err = gpfs_prealloc(fd, (gpfs_off64_t)0, (gpfs_off64_t)size);
  90 #endif
  91
  92         if (err) {
  93                 DEBUG(module_debug,
  94                         ("%s: preallocate failed on fd=%d size=%lld: %s\n",
  95                         MODULE, fd, (long long)size, strerror(errno)));
  96         }
  97
  98         return err;
  99 }
 100
 101 static int prealloc_connect(
 102                 struct vfs_handle_struct *  handle,
 103                 const char *                service,
 104                 const char *                user)
 105 {
 106         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 107
 108         if (ret < 0) {
 109                 return ret;
 110         }
 111
 112         module_debug = lp_parm_int(SNUM(handle->conn),
 113                                         MODULE, "debug", 100);
 114
 115         return 0;
 116 }
 117
 118 static int prealloc_open(vfs_handle_struct* handle,
 119                         struct smb_filename *smb_fname,
 120                         files_struct *      fsp,
 121                         int                 flags,
 122                         mode_t              mode)
 123 {
 124         int fd;
 125         off_t size = 0;
 126
 127         const char * dot;
 128         char fext[10];
 129
 130         if (!(flags & (O_CREAT|O_TRUNC))) {
 131                 /* Caller is not intending to rewrite the file. Let's not mess
 132                  * with the allocation in this case.
 133                  */
 134                 goto normal_open;
 135         }
 136
 137         *fext = '\0';
 138         dot = strrchr(smb_fname->base_name, '.');
 139         if (dot && *++dot) {
 140                 if (strlen(dot) < sizeof(fext)) {
 141                         strncpy(fext, dot, sizeof(fext));
 142                         strnorm(fext, CASE_LOWER);
 143                 }
 144         }
 145
 146         if (*fext == '\0') {
 147                 goto normal_open;
 148         }
 149
 150         /* Syntax for specifying preallocation size is:
 151          *      MODULE: <extension> = <size>
 152          * where
 153          *      <extension> is the file extension in lower case
 154          *      <size> is a size like 10, 10K, 10M
 155          */
 156         size = conv_str_size(lp_parm_const_string(SNUM(handle->conn), MODULE,
 157                                                     fext, NULL));
 158         if (size <= 0) {
 159                 /* No need to preallocate this file. */
 160                 goto normal_open;
 161         }
 162
 163         fd = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 164         if (fd < 0) {
 165                 return fd;
 166         }
 167
 168         /* Prellocate only if the file is being created or replaced. Note that
 169          * Samba won't ever pass down O_TRUNC, which is why we have to handle
 170          * truncate calls specially.
 171          */
 172         if ((flags & O_CREAT) || (flags & O_TRUNC)) {
 173                 off_t * psize;
 174
 175                 psize = VFS_ADD_FSP_EXTENSION(handle, fsp, off_t, NULL);
 176                 if (psize == NULL || *psize == -1) {
 177                         return fd;
 178                 }
 179
 180                 DEBUG(module_debug,
 181                         ("%s: preallocating %s (fd=%d) to %lld bytes\n",
 182                             MODULE, smb_fname_str_dbg(smb_fname), fd,
 183                             (long long)size));
 184
 185                 *psize = size;
 186                 if (preallocate_space(fd, *psize) < 0) {
 187                         VFS_REMOVE_FSP_EXTENSION(handle, fsp);
 188                 }
 189         }
 190
 191         return fd;
 192
 193 normal_open:
 194         /* We are not creating or replacing a file. Skip the
 195          * preallocation.
 196          */
 197         DEBUG(module_debug, ("%s: skipping preallocation for %s\n",
 198                 MODULE, smb_fname_str_dbg(smb_fname)));
 199         return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
 200 }
 201
 202 static int prealloc_ftruncate(vfs_handle_struct * handle,
 203                         files_struct *  fsp,
 204                         off_t   offset)
 205 {
 206         off_t *psize;
 207         int ret = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, offset);
 208
 209         /* Maintain the allocated space even in the face of truncates. */
 210         if ((psize = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
 211                 preallocate_space(fsp->fh->fd, *psize);
 212         }
 213
 214         return ret;
 215 }
 216
 217 static struct vfs_fn_pointers prealloc_fns = {
 218         .open_fn = prealloc_open,
 219         .ftruncate_fn = prealloc_ftruncate,
 220         .connect_fn = prealloc_connect,
 221 };
 222
 223 NTSTATUS vfs_prealloc_init(void);
 224 NTSTATUS vfs_prealloc_init(void)
 225 {
 226         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 227                                 MODULE, &prealloc_fns);
 228 }