source/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 struct readahead_data {
  21         SMB_OFF_T off_bound;
  22         SMB_OFF_T len;
  23         bool didmsg;
  24 };
  25
  26 /*
  27  * This module copes with Vista AIO read requests on Linux
  28  * by detecting the initial 0x80000 boundary reads and causing
  29  * the buffer cache to be filled in advance.
  30  */
  31
  32 /*******************************************************************
  33  sendfile wrapper that does readahead/posix_fadvise.
  34 *******************************************************************/
  35
  36 static ssize_t readahead_sendfile(struct vfs_handle_struct *handle,
  37                                         int tofd,
  38                                         files_struct *fromfsp,
  39                                         const DATA_BLOB *header,
  40                                         SMB_OFF_T offset,
  41                                         size_t count)
  42 {
  43         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  44
  45         if ( offset % rhd->off_bound == 0) {
  46 #if defined(HAVE_LINUX_READAHEAD)
  47                 int err = readahead(fromfsp->fh->fd, offset, (size_t)rhd->len);
  48                 DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
  49                         (unsigned int)fromfsp->fh->fd,
  50                         (unsigned long long)offset,
  51                         (unsigned int)rhd->len,
  52                         err ));
  53 #elif defined(HAVE_POSIX_FADVISE)
  54                 int err = posix_fadvise(fromfsp->fh->fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
  55                 DEBUG(10,("readahead_sendfile: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  56                         (unsigned int)fromfsp->fh->fd,
  57                         (unsigned long long)offset,
  58                         (unsigned int)rhd->len,
  59                         err ));
  60 #else
  61                 if (!rhd->didmsg) {
  62                         DEBUG(0,("readahead_sendfile: no readahead on this platform\n"));
  63                         rhd->didmsg = True;
  64                 }
  65 #endif
  66         }
  67         return SMB_VFS_NEXT_SENDFILE(handle,
  68                                         tofd,
  69                                         fromfsp,
  70                                         header,
  71                                         offset,
  72                                         count);
  73 }
  74
  75 /*******************************************************************
  76  pread wrapper that does readahead/posix_fadvise.
  77 *******************************************************************/
  78
  79 static ssize_t readahead_pread(vfs_handle_struct *handle,
  80                                 files_struct *fsp,
  81                                 void *data,
  82                                 size_t count,
  83                                 SMB_OFF_T offset)
  84 {
  85         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  86
  87         if ( offset % rhd->off_bound == 0) {
  88 #if defined(HAVE_LINUX_READAHEAD)
  89                 int err = readahead(fsp->fh->fd, offset, (size_t)rhd->len);
  90                 DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
  91                         (unsigned int)fsp->fh->fd,
  92                         (unsigned long long)offset,
  93                         (unsigned int)rhd->len,
  94                         err ));
  95 #elif defined(HAVE_POSIX_FADVISE)
  96                 int err = posix_fadvise(fsp->fh->fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
  97                 DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  98                         (unsigned int)fsp->fh->fd,
  99                         (unsigned long long)offset,
 100                         (unsigned int)rhd->len,
 101                         err ));
 102 #else
 103                 if (!rhd->didmsg) {
 104                         DEBUG(0,("readahead_pread: no readahead on this platform\n"));
 105                         rhd->didmsg = True;
 106                 }
 107 #endif
 108         }
 109         return SMB_VFS_NEXT_PREAD(handle, fsp, data, count, offset);
 110 }
 111
 112 /*******************************************************************
 113  Directly called from main smbd when freeing handle.
 114 *******************************************************************/
 115
 116 static void free_readahead_data(void **pptr)
 117 {
 118         SAFE_FREE(*pptr);
 119 }
 120
 121 /*******************************************************************
 122  Allocate the handle specific data so we don't call the expensive
 123  conv_str_size function for each sendfile/pread.
 124 *******************************************************************/
 125
 126 static int readahead_connect(struct vfs_handle_struct *handle,
 127                                 const char *service,
 128                                 const char *user)
 129 {
 130         struct readahead_data *rhd = SMB_MALLOC_P(struct readahead_data);
 131         if (!rhd) {
 132                 DEBUG(0,("readahead_connect: out of memory\n"));
 133                 return -1;
 134         }
 135         ZERO_STRUCTP(rhd);
 136
 137         rhd->didmsg = False;
 138         rhd->off_bound = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 139                                                 "readahead",
 140                                                 "offset",
 141                                                 NULL));
 142         if (rhd->off_bound == 0) {
 143                 rhd->off_bound = 0x80000;
 144         }
 145         rhd->len = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 146                                                 "readahead",
 147                                                 "length",
 148                                                 NULL));
 149         if (rhd->len == 0) {
 150                 rhd->len = rhd->off_bound;
 151         }
 152
 153         handle->data = (void *)rhd;
 154         handle->free_data = free_readahead_data;
 155         return SMB_VFS_NEXT_CONNECT(handle, service, user);
 156 }
 157
 158 /*******************************************************************
 159  Functions we're replacing.
 160  We don't replace read as it isn't used from smbd to read file
 161  data.
 162 *******************************************************************/
 163
 164 static vfs_op_tuple readahead_ops [] =
 165 {
 166         {SMB_VFS_OP(readahead_sendfile), SMB_VFS_OP_SENDFILE, SMB_VFS_LAYER_TRANSPARENT},
 167         {SMB_VFS_OP(readahead_pread), SMB_VFS_OP_PREAD, SMB_VFS_LAYER_TRANSPARENT},
 168         {SMB_VFS_OP(readahead_connect), SMB_VFS_OP_CONNECT,  SMB_VFS_LAYER_TRANSPARENT},
 169         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 170 };
 171
 172 /*******************************************************************
 173  Module initialization boilerplate.
 174 *******************************************************************/
 175
 176 NTSTATUS vfs_readahead_init(void);
 177 NTSTATUS vfs_readahead_init(void)
 178 {
 179         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "readahead", readahead_ops);
 180 }