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 #include "smbd/smbd.h"
  21
  22 #if defined(HAVE_LINUX_READAHEAD) && ! defined(HAVE_READAHEAD_DECL)
  23 ssize_t readahead(int fd, off_t offset, size_t count);
  24 #endif
  25
  26 struct readahead_data {
  27         off_t off_bound;
  28         off_t len;
  29         bool didmsg;
  30 };
  31
  32 /*
  33  * This module copes with Vista AIO read requests on Linux
  34  * by detecting the initial 0x80000 boundary reads and causing
  35  * the buffer cache to be filled in advance.
  36  */
  37
  38 /*******************************************************************
  39  sendfile wrapper that does readahead/posix_fadvise.
  40 *******************************************************************/
  41
  42 static ssize_t readahead_sendfile(struct vfs_handle_struct *handle,
  43                                         int tofd,
  44                                         files_struct *fromfsp,
  45                                         const DATA_BLOB *header,
  46                                         off_t offset,
  47                                         size_t count)
  48 {
  49         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  50
  51         if ( offset % rhd->off_bound == 0) {
  52 #if defined(HAVE_LINUX_READAHEAD)
  53                 int err = readahead(fromfsp->fh->fd, offset, (size_t)rhd->len);
  54                 DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
  55                         (unsigned int)fromfsp->fh->fd,
  56                         (unsigned long long)offset,
  57                         (unsigned int)rhd->len,
  58                         err ));
  59 #elif defined(HAVE_POSIX_FADVISE)
  60                 int err = posix_fadvise(fromfsp->fh->fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
  61                 DEBUG(10,("readahead_sendfile: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  62                         (unsigned int)fromfsp->fh->fd,
  63                         (unsigned long long)offset,
  64                         (unsigned int)rhd->len,
  65                         err ));
  66 #else
  67                 if (!rhd->didmsg) {
  68                         DEBUG(0,("readahead_sendfile: no readahead on this platform\n"));
  69                         rhd->didmsg = True;
  70                 }
  71 #endif
  72         }
  73         return SMB_VFS_NEXT_SENDFILE(handle,
  74                                         tofd,
  75                                         fromfsp,
  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                                 void *data,
  88                                 size_t count,
  89                                 off_t offset)
  90 {
  91         struct readahead_data *rhd = (struct readahead_data *)handle->data;
  92
  93         if ( offset % rhd->off_bound == 0) {
  94 #if defined(HAVE_LINUX_READAHEAD)
  95                 int err = readahead(fsp->fh->fd, offset, (size_t)rhd->len);
  96                 DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
  97                         (unsigned int)fsp->fh->fd,
  98                         (unsigned long long)offset,
  99                         (unsigned int)rhd->len,
 100                         err ));
 101 #elif defined(HAVE_POSIX_FADVISE)
 102                 int err = posix_fadvise(fsp->fh->fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
 103                 DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
 104                         (unsigned int)fsp->fh->fd,
 105                         (unsigned long long)offset,
 106                         (unsigned int)rhd->len,
 107                         err ));
 108 #else
 109                 if (!rhd->didmsg) {
 110                         DEBUG(0,("readahead_pread: no readahead on this platform\n"));
 111                         rhd->didmsg = True;
 112                 }
 113 #endif
 114         }
 115         return SMB_VFS_NEXT_PREAD(handle, fsp, data, count, offset);
 116 }
 117
 118 /*******************************************************************
 119  Directly called from main smbd when freeing handle.
 120 *******************************************************************/
 121
 122 static void free_readahead_data(void **pptr)
 123 {
 124         SAFE_FREE(*pptr);
 125 }
 126
 127 /*******************************************************************
 128  Allocate the handle specific data so we don't call the expensive
 129  conv_str_size function for each sendfile/pread.
 130 *******************************************************************/
 131
 132 static int readahead_connect(struct vfs_handle_struct *handle,
 133                                 const char *service,
 134                                 const char *user)
 135 {
 136         struct readahead_data *rhd;
 137         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 138
 139         if (ret < 0) {
 140                 return ret;
 141         }
 142         rhd = SMB_MALLOC_P(struct readahead_data);
 143         if (!rhd) {
 144                 SMB_VFS_NEXT_DISCONNECT(handle);
 145                 DEBUG(0,("readahead_connect: out of memory\n"));
 146                 return -1;
 147         }
 148         ZERO_STRUCTP(rhd);
 149
 150         rhd->didmsg = False;
 151         rhd->off_bound = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 152                                                 "readahead",
 153                                                 "offset",
 154                                                 NULL));
 155         if (rhd->off_bound == 0) {
 156                 rhd->off_bound = 0x80000;
 157         }
 158         rhd->len = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
 159                                                 "readahead",
 160                                                 "length",
 161                                                 NULL));
 162         if (rhd->len == 0) {
 163                 rhd->len = rhd->off_bound;
 164         }
 165
 166         handle->data = (void *)rhd;
 167         handle->free_data = free_readahead_data;
 168         return 0;
 169 }
 170
 171 static struct vfs_fn_pointers vfs_readahead_fns = {
 172         .sendfile_fn = readahead_sendfile,
 173         .pread_fn = readahead_pread,
 174         .connect_fn = readahead_connect
 175 };
 176
 177 /*******************************************************************
 178  Module initialization boilerplate.
 179 *******************************************************************/
 180
 181 NTSTATUS vfs_readahead_init(void);
 182 NTSTATUS vfs_readahead_init(void)
 183 {
 184         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "readahead",
 185                                 &vfs_readahead_fns);
 186 }