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 #include "system/filesys.h"
  20
  21 struct readahead_data {
  22         SMB_OFF_T off_bound;
  23         SMB_OFF_T len;
  24         bool didmsg;
  25 };
  26
  27 /*
  28  * This module copes with Vista AIO read requests on Linux
  29  * by detecting the initial 0x80000 boundary reads and causing
  30  * the buffer cache to be filled in advance.
  31  */
  32
  33 /*******************************************************************
  34  sendfile wrapper that does readahead/posix_fadvise.
  35 *******************************************************************/
  36
  37 static ssize_t readahead_sendfile(struct vfs_handle_struct *handle,
  38                                         int tofd,
  39                                         files_struct *fromfsp,
  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(fromfsp->fh->fd, offset, (size_t)rhd->len);
  49                 DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
  50                         (unsigned int)fromfsp->fh->fd,
  51                         (unsigned long long)offset,
  52                         (unsigned int)rhd->len,
  53                         err ));
  54 #elif defined(HAVE_POSIX_FADVISE)
  55                 int err = posix_fadvise(fromfsp->fh->fd, 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)fromfsp->fh->fd,
  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                                         fromfsp,
  71                                         header,
  72                                         offset,
  73                                         count);
  74 }
  75
  76 /*******************************************************************
  77  pread wrapper that does readahead/posix_fadvise.
  78 *******************************************************************/
  79
  80 static ssize_t readahead_pread(vfs_handle_struct *handle,
  81                                 files_struct *fsp,
  82                                 void *data,
  83                                 size_t count,
  84                                 SMB_OFF_T offset)
  85 {
  86         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  87
  88         if ( offset % rhd->off_bound == 0) {
  89 #if defined(HAVE_LINUX_READAHEAD)
  90                 int err = readahead(fsp->fh->fd, offset, (size_t)rhd->len);
  91                 DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
  92                         (unsigned int)fsp->fh->fd,
  93                         (unsigned long long)offset,
  94                         (unsigned int)rhd->len,
  95                         err ));
  96 #elif defined(HAVE_POSIX_FADVISE)
  97                 int err = posix_fadvise(fsp->fh->fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
  98                 DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  99                         (unsigned int)fsp->fh->fd,
 100                         (unsigned long long)offset,
 101                         (unsigned int)rhd->len,
 102                         err ));
 103 #else
 104                 if (!rhd->didmsg) {
 105                         DEBUG(0,("readahead_pread: no readahead on this platform\n"));
 106                         rhd->didmsg = True;
 107                 }
 108 #endif
 109         }
 110         return SMB_VFS_NEXT_PREAD(handle, fsp, data, count, offset);
 111 }
 112
 113 /*******************************************************************
 114  Directly called from main smbd when freeing handle.
 115 *******************************************************************/
 116
 117 static void free_readahead_data(void **pptr)
 118 {
 119         SAFE_FREE(*pptr);
 120 }
 121
 122 /*******************************************************************
 123  Allocate the handle specific data so we don't call the expensive
 124  conv_str_size function for each sendfile/pread.
 125 *******************************************************************/
 126
 127 static int readahead_connect(struct vfs_handle_struct *handle,
 128                                 const char *service,
 129                                 const char *user)
 130 {
 131         struct readahead_data *rhd;
 132         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 133
 134         if (ret < 0) {
 135                 return ret;
 136         }
 137         rhd = SMB_MALLOC_P(struct readahead_data);
 138         if (!rhd) {
 139                 SMB_VFS_NEXT_DISCONNECT(handle);
 140                 DEBUG(0,("readahead_connect: out of memory\n"));
 141                 return -1;
 142         }
 143         ZERO_STRUCTP(rhd);
 144
 145         rhd->didmsg = False;
 146         rhd->off_bound = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 147                                                 "readahead",
 148                                                 "offset",
 149                                                 NULL));
 150         if (rhd->off_bound == 0) {
 151                 rhd->off_bound = 0x80000;
 152         }
 153         rhd->len = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 154                                                 "readahead",
 155                                                 "length",
 156                                                 NULL));
 157         if (rhd->len == 0) {
 158                 rhd->len = rhd->off_bound;
 159         }
 160
 161         handle->data = (void *)rhd;
 162         handle->free_data = free_readahead_data;
 163         return 0;
 164 }
 165
 166 static struct vfs_fn_pointers vfs_readahead_fns = {
 167         .sendfile = readahead_sendfile,
 168         .pread = readahead_pread,
 169         .connect_fn = readahead_connect
 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",
 180                                 &vfs_readahead_fns);
 181 }