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 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 *fsp,
  39                                         int fromfd,
  40                                         const DATA_BLOB *header,
  41                                         SMB_OFF_T offset,
  42                                         size_t count)
  43 {
  44         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  45
  46         if ( offset % rhd->off_bound == 0) {
  47 #if defined(HAVE_LINUX_READAHEAD)
  48                 int err = readahead(fromfd, offset, (size_t)rhd->len);
  49                 DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
  50                         (unsigned int)fromfd,
  51                         (unsigned long long)offset,
  52                         (unsigned int)rhd->len,
  53                         err ));
  54 #elif defined(HAVE_POSIX_FADVISE)
  55                 int err = posix_fadvise(fromfd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
  56                 DEBUG(10,("readahead_sendfile: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  57                         (unsigned int)fromfd,
  58                         (unsigned long long)offset,
  59                         (unsigned int)rhd->len,
  60                         err ));
  61 #else
  62                 if (!rhd->didmsg) {
  63                         DEBUG(0,("readahead_sendfile: no readahead on this platform\n"));
  64                         rhd->didmsg = True;
  65                 }
  66 #endif
  67         }
  68         return SMB_VFS_NEXT_SENDFILE(handle,
  69                                         tofd,
  70                                         fsp,
  71                                         fromfd,
  72                                         header,
  73                                         offset,
  74                                         count);
  75 }
  76
  77 /*******************************************************************
  78  pread wrapper that does readahead/posix_fadvise.
  79 *******************************************************************/
  80
  81 static ssize_t readahead_pread(vfs_handle_struct *handle,
  82                                 files_struct *fsp,
  83                                 void *data,
  84                                 size_t count,
  85                                 SMB_OFF_T offset)
  86 {
  87         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  88
  89         if ( offset % rhd->off_bound == 0) {
  90 #if defined(HAVE_LINUX_READAHEAD)
  91                 int err = readahead(fsp->fh->fd, offset, (size_t)rhd->len);
  92                 DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
  93                         (unsigned int)fsp->fh->fd,
  94                         (unsigned long long)offset,
  95                         (unsigned int)rhd->len,
  96                         err ));
  97 #elif defined(HAVE_POSIX_FADVISE)
  98                 int err = posix_fadvise(fsp->fh->fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
  99                 DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
 100                         (unsigned int)fsp->fh->fd,
 101                         (unsigned long long)offset,
 102                         (unsigned int)rhd->len,
 103                         err ));
 104 #else
 105                 if (!rhd->didmsg) {
 106                         DEBUG(0,("readahead_pread: no readahead on this platform\n"));
 107                         rhd->didmsg = True;
 108                 }
 109 #endif
 110         }
 111         return SMB_VFS_NEXT_PREAD(handle, fsp, data, count, offset);
 112 }
 113
 114 /*******************************************************************
 115  Directly called from main smbd when freeing handle.
 116 *******************************************************************/
 117
 118 static void free_readahead_data(void **pptr)
 119 {
 120         SAFE_FREE(*pptr);
 121 }
 122
 123 /*******************************************************************
 124  Allocate the handle specific data so we don't call the expensive
 125  conv_str_size function for each sendfile/pread.
 126 *******************************************************************/
 127
 128 static int readahead_connect(struct vfs_handle_struct *handle,
 129                                 const char *service,
 130                                 const char *user)
 131 {
 132         struct readahead_data *rhd = SMB_MALLOC_P(struct readahead_data);
 133         if (!rhd) {
 134                 DEBUG(0,("readahead_connect: out of memory\n"));
 135                 return -1;
 136         }
 137         ZERO_STRUCTP(rhd);
 138
 139         rhd->didmsg = False;
 140         rhd->off_bound = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 141                                                 "readahead",
 142                                                 "offset",
 143                                                 NULL));
 144         if (rhd->off_bound == 0) {
 145                 rhd->off_bound = 0x80000;
 146         }
 147         rhd->len = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 148                                                 "readahead",
 149                                                 "length",
 150                                                 NULL));
 151         if (rhd->len == 0) {
 152                 rhd->len = rhd->off_bound;
 153         }
 154
 155         handle->data = (void *)rhd;
 156         handle->free_data = free_readahead_data;
 157         return SMB_VFS_NEXT_CONNECT(handle, service, user);
 158 }
 159
 160 /*******************************************************************
 161  Functions we're replacing.
 162  We don't replace read as it isn't used from smbd to read file
 163  data.
 164 *******************************************************************/
 165
 166 static vfs_op_tuple readahead_ops [] =
 167 {
 168         {SMB_VFS_OP(readahead_sendfile), SMB_VFS_OP_SENDFILE, SMB_VFS_LAYER_TRANSPARENT},
 169         {SMB_VFS_OP(readahead_pread), SMB_VFS_OP_PREAD, SMB_VFS_LAYER_TRANSPARENT},
 170         {SMB_VFS_OP(readahead_connect), SMB_VFS_OP_CONNECT,  SMB_VFS_LAYER_TRANSPARENT},
 171         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 172 };
 173
 174 /*******************************************************************
 175  Module initialization boilerplate.
 176 *******************************************************************/
 177
 178 NTSTATUS vfs_readahead_init(void);
 179 NTSTATUS vfs_readahead_init(void)
 180 {
 181         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "readahead", readahead_ops);
 182 }