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 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 unsigned long get_offset_boundary(struct vfs_handle_struct *handle)
  32 {
  33         SMB_OFF_T off_bound = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
  34                                                 "readahead",
  35                                                 "offset",
  36                                                 NULL));
  37         if (off_bound == 0) {
  38                 off_bound = 0x80000;
  39         }
  40         return (unsigned long)off_bound;
  41 }
  42
  43 static unsigned long get_offset_length(struct vfs_handle_struct *handle, unsigned long def_val)
  44 {
  45         SMB_OFF_T len = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
  46                                                 "readahead",
  47                                                 "length",
  48                                                 NULL));
  49         if (len == 0) {
  50                 len = def_val;
  51         }
  52         return (unsigned long)len;
  53 }
  54
  55 static ssize_t readahead_sendfile(struct vfs_handle_struct *handle,
  56                                         int tofd,
  57                                         files_struct *fsp,
  58                                         int fromfd,
  59                                         const DATA_BLOB *header,
  60                                         SMB_OFF_T offset,
  61                                         size_t count)
  62 {
  63         unsigned long off_bound = get_offset_boundary(handle);
  64         if ( offset % off_bound == 0) {
  65                 unsigned long len = get_offset_length(handle, off_bound);
  66 #if defined(HAVE_LINUX_READAHEAD)
  67                 int err = readahead(fromfd, offset, (size_t)len);
  68                 DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
  69                         (unsigned int)fromfd,
  70                         (unsigned long long)offset,
  71                         (unsigned int)len,
  72                         err ));
  73 #elif defined(HAVE_POSIX_FADVISE)
  74                 int err = posix_fadvise(fromfd, offset, (off_t)len, POSIX_FADV_WILLNEED);
  75                 DEBUG(10,("readahead_sendfile: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
  76                         (unsigned int)fromfd,
  77                         (unsigned long long)offset,
  78                         (unsigned int)len,
  79                         err ));
  80 #else
  81                 if (!didmsg) {
  82                         DEBUG(0,("readahead_sendfile: no readahead on this platform\n"));
  83                         didmsg = True;
  84                 }
  85 #endif
  86         }
  87         return SMB_VFS_NEXT_SENDFILE(handle,
  88                                         tofd,
  89                                         fsp,
  90                                         fromfd,
  91                                         header,
  92                                         offset,
  93                                         count);
  94 }
  95
  96 static ssize_t readahead_pread(vfs_handle_struct *handle,
  97                                 files_struct *fsp,
  98                                 int fd,
  99                                 void *data,
 100                                 size_t count,
 101                                 SMB_OFF_T offset)
 102 {
 103         unsigned long off_bound = get_offset_boundary(handle);
 104         if ( offset % off_bound == 0) {
 105                 unsigned long len = get_offset_length(handle, off_bound);
 106 #if defined(HAVE_LINUX_READAHEAD)
 107                 int err = readahead(fd, offset, (size_t)len);
 108                 DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
 109                         (unsigned int)fd,
 110                         (unsigned long long)offset,
 111                         (unsigned int)len,
 112                         err ));
 113 #elif defined(HAVE_POSIX_FADVISE)
 114                 int err = posix_fadvise(fromfd, offset, (off_t)len, POSIX_FADV_WILLNEED);
 115                 DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
 116                         (unsigned int)fd,
 117                         (unsigned long long)offset,
 118                         (unsigned int)len,
 119                         (err ));
 120 #else
 121                 if (!didmsg) {
 122                         DEBUG(0,("readahead_pread: no readahead on this platform\n"));
 123                         didmsg = True;
 124                 }
 125 #endif
 126         }
 127         return SMB_VFS_NEXT_PREAD(handle, fsp, fd, data, count, offset);
 128 }
 129
 130 static vfs_op_tuple readahead_ops [] =
 131 {
 132         {SMB_VFS_OP(readahead_sendfile), SMB_VFS_OP_SENDFILE, SMB_VFS_LAYER_TRANSPARENT},
 133         {SMB_VFS_OP(readahead_pread), SMB_VFS_OP_PREAD, SMB_VFS_LAYER_TRANSPARENT},
 134         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 135 };
 136
 137 NTSTATUS vfs_readahead_init(void);
 138 NTSTATUS vfs_readahead_init(void)
 139 {
 140         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "readahead", readahead_ops);
 141 }