source3/modules/vfs_readahead.c

   1 /*
   2  * Copyright (c) Jeremy Allison 2007.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include "includes.h"
  19
  20 #if !defined(HAVE_LINUX_READAHEAD) && !defined(HAVE_POSIX_FADVISE)
  21 static BOOL didmsg;
  22 #endif
  23
  24 struct readahead_data {
  25         SMB_OFF_T off_bound;
  26         SMB_OFF_T len;
  27         BOOL didmsg;
  28 };
  29
  30 /*
  31  * This module copes with Vista AIO read requests on Linux
  32  * by detecting the initial 0x80000 boundary reads and causing
  33  * the buffer cache to be filled in advance.
  34  */
  35
  36 /*******************************************************************
  37  sendfile wrapper that does readahead/posix_fadvise.
  38 *******************************************************************/
  39
  40 static ssize_t readahead_sendfile(struct vfs_handle_struct *handle,
  41                                         int tofd,
  42                                         files_struct *fsp,
  43                                         int fromfd,
  44                                         const DATA_BLOB *header,
  45                                         SMB_OFF_T offset,
  46                                         size_t count)
  47 {
  48         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  49
  50         if ( offset % rhd->off_bound == 0) {
  51 #if defined(HAVE_LINUX_READAHEAD)
  52                 int err = readahead(fromfd, offset, (size_t)rhd->len);
  53                 DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
  54                         (unsigned int)fromfd,
  55                         (unsigned long long)offset,
  56                         (unsigned int)rhd->len,
  57                         err ));
  58 #elif defined(HAVE_POSIX_FADVISE)
  59                 int err = posix_fadvise(fromfd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
  60                 DEBUG(10,("readahead_sendfile: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  61                         (unsigned int)fromfd,
  62                         (unsigned long long)offset,
  63                         (unsigned int)rhd->len,
  64                         err ));
  65 #else
  66                 if (!rhd->didmsg) {
  67                         DEBUG(0,("readahead_sendfile: no readahead on this platform\n"));
  68                         rhd->didmsg = True;
  69                 }
  70 #endif
  71         }
  72         return SMB_VFS_NEXT_SENDFILE(handle,
  73                                         tofd,
  74                                         fsp,
  75                                         fromfd,
  76                                         header,
  77                                         offset,
  78                                         count);
  79 }
  80
  81 /*******************************************************************
  82  pread wrapper that does readahead/posix_fadvise.
  83 *******************************************************************/
  84
  85 static ssize_t readahead_pread(vfs_handle_struct *handle,
  86                                 files_struct *fsp,
  87                                 int fd,
  88                                 void *data,
  89                                 size_t count,
  90                                 SMB_OFF_T offset)
  91 {
  92         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  93
  94         if ( offset % rhd->off_bound == 0) {
  95 #if defined(HAVE_LINUX_READAHEAD)
  96                 int err = readahead(fd, offset, (size_t)rhd->len);
  97                 DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
  98                         (unsigned int)fd,
  99                         (unsigned long long)offset,
 100                         (unsigned int)rhd->len,
 101                         err ));
 102 #elif defined(HAVE_POSIX_FADVISE)
 103                 int err = posix_fadvise(fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
 104                 DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
 105                         (unsigned int)fd,
 106                         (unsigned long long)offset,
 107                         (unsigned int)rhd->len,
 108                         err ));
 109 #else
 110                 if (!rhd->didmsg) {
 111                         DEBUG(0,("readahead_pread: no readahead on this platform\n"));
 112                         rhd->didmsg = True;
 113                 }
 114 #endif
 115         }
 116         return SMB_VFS_NEXT_PREAD(handle, fsp, fd, data, count, offset);
 117 }
 118
 119 /*******************************************************************
 120  Directly called from main smbd when freeing handle.
 121 *******************************************************************/
 122
 123 static void free_readahead_data(void **pptr)
 124 {
 125         SAFE_FREE(*pptr);
 126 }
 127
 128 /*******************************************************************
 129  Allocate the handle specific data so we don't call the expensive
 130  conv_str_size function for each sendfile/pread.
 131 *******************************************************************/
 132
 133 static int readahead_connect(struct vfs_handle_struct *handle,
 134                                 const char *service,
 135                                 const char *user)
 136 {
 137         struct readahead_data *rhd = SMB_MALLOC_P(struct readahead_data);
 138         if (!rhd) {
 139                 DEBUG(0,("readahead_connect: out of memory\n"));
 140                 return -1;
 141         }
 142         ZERO_STRUCTP(rhd);
 143
 144         rhd->didmsg = False;
 145         rhd->off_bound = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 146                                                 "readahead",
 147                                                 "offset",
 148                                                 NULL));
 149         if (rhd->off_bound == 0) {
 150                 rhd->off_bound = 0x80000;
 151         }
 152         rhd->len = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 153                                                 "readahead",
 154                                                 "length",
 155                                                 NULL));
 156         if (rhd->len == 0) {
 157                 rhd->len = rhd->off_bound;
 158         }
 159
 160         handle->data = (void *)rhd;
 161         handle->free_data = free_readahead_data;
 162         return 0;
 163 }
 164
 165 /*******************************************************************
 166  Functions we're replacing.
 167  We don't replace read as it isn't used from smbd to read file
 168  data.
 169 *******************************************************************/
 170
 171 static vfs_op_tuple readahead_ops [] =
 172 {
 173         {SMB_VFS_OP(readahead_sendfile), SMB_VFS_OP_SENDFILE, SMB_VFS_LAYER_TRANSPARENT},
 174         {SMB_VFS_OP(readahead_pread), SMB_VFS_OP_PREAD, SMB_VFS_LAYER_TRANSPARENT},
 175         {SMB_VFS_OP(readahead_connect), SMB_VFS_OP_CONNECT,  SMB_VFS_LAYER_TRANSPARENT},
 176         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 177 };
 178
 179 /*******************************************************************
 180  Module initialization boilerplate.
 181 *******************************************************************/
 182
 183 NTSTATUS vfs_readahead_init(void);
 184 NTSTATUS vfs_readahead_init(void)
 185 {
 186         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "readahead", readahead_ops);
 187 }