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 2 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, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include "includes.h"
  20
  21 #if !defined(HAVE_LINUX_READAHEAD) && !defined(HAVE_POSIX_FADVISE)
  22 static BOOL didmsg;
  23 #endif
  24
  25 /*
  26  * This module copes with Vista AIO read requests on Linux
  27  * by detecting the initial 0x80000 boundary reads and causing
  28  * the buffer cache to be filled in advance.
  29  */
  30
  31 static ssize_t readahead_sendfile(struct vfs_handle_struct *handle,
  32                                         int tofd,
  33                                         files_struct *fsp,
  34                                         int fromfd,
  35                                         const DATA_BLOB *header,
  36                                         SMB_OFF_T offset,
  37                                         size_t count)
  38 {
  39         unsigned long off_bound = lp_parm_ulong(SNUM(handle->conn), "readahead", "offset", 0x80000);
  40         if ( offset % off_bound == 0) {
  41                 unsigned long len = lp_parm_ulong(SNUM(handle->conn), "readahead", "length", off_bound);
  42 #if defined(HAVE_LINUX_READAHEAD)
  43                 int err = readahead(fromfd, offset, (size_t)len);
  44                 DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
  45                         (unsigned int)fromfd,
  46                         (unsigned long long)offset,
  47                         (unsigned int)len,
  48                         err ));
  49 #elif defined(HAVE_POSIX_FADVISE)
  50                 int err = posix_fadvise(fromfd, offset, (off_t)len, POSIX_FADV_WILLNEED);
  51                 DEBUG(10,("readahead_sendfile: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  52                         (unsigned int)fromfd,
  53                         (unsigned long long)offset,
  54                         (unsigned int)len,
  55                         err ));
  56 #else
  57                 if (!didmsg) {
  58                         DEBUG(0,("readahead_sendfile: no readahead on this platform\n"));
  59                         didmsg = True;
  60                 }
  61 #endif
  62         }
  63         return SMB_VFS_NEXT_SENDFILE(handle,
  64                                         tofd,
  65                                         fsp,
  66                                         fromfd,
  67                                         header,
  68                                         offset,
  69                                         count);
  70 }
  71
  72 static ssize_t readahead_pread(vfs_handle_struct *handle,
  73                                 files_struct *fsp,
  74                                 int fd,
  75                                 void *data,
  76                                 size_t count,
  77                                 SMB_OFF_T offset)
  78 {
  79         unsigned long off_bound = lp_parm_ulong(SNUM(handle->conn), "readahead", "offset", 0x80000);
  80         if ( offset % off_bound == 0) {
  81                 unsigned long len = lp_parm_ulong(SNUM(handle->conn), "readahead", "length", off_bound);
  82 #if defined(HAVE_LINUX_READAHEAD)
  83                 int err = readahead(fd, offset, (size_t)len);
  84                 DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
  85                         (unsigned int)fd,
  86                         (unsigned long long)offset,
  87                         (unsigned int)len,
  88                         err ));
  89 #elif defined(HAVE_POSIX_FADVISE)
  90                 int err = posix_fadvise(fromfd, offset, (off_t)len, POSIX_FADV_WILLNEED);
  91                 DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  92                         (unsigned int)fd,
  93                         (unsigned long long)offset,
  94                         (unsigned int)len,
  95                         (err ));
  96 #else
  97                 if (!didmsg) {
  98                         DEBUG(0,("readahead_pread: no readahead on this platform\n"));
  99                         didmsg = True;
 100                 }
 101 #endif
 102         }
 103         return SMB_VFS_NEXT_PREAD(handle, fsp, fd, data, count, offset);
 104 }
 105
 106 static vfs_op_tuple readahead_ops [] =
 107 {
 108         {SMB_VFS_OP(readahead_sendfile), SMB_VFS_OP_SENDFILE, SMB_VFS_LAYER_TRANSPARENT},
 109         {SMB_VFS_OP(readahead_pread), SMB_VFS_OP_PREAD, SMB_VFS_LAYER_TRANSPARENT},
 110         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 111 };
 112
 113 NTSTATUS vfs_readahead_init(void);
 114 NTSTATUS vfs_readahead_init(void)
 115 {
 116         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "readahead", readahead_ops);
 117 }