source: trunk/samba/source/modules/vfs_readahead.c @ 30

Last change on this file since 30 was 30, checked in by Paul Smedley, 14 years ago

Code updated to Samba 3.0.25rc2 level

File size: 5.9 KB
Line 
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)
22static BOOL didmsg;
23#endif
24
25struct readahead_data {
26        SMB_OFF_T off_bound;
27        SMB_OFF_T len;
28        BOOL didmsg;
29};
30
31/*
32 * This module copes with Vista AIO read requests on Linux
33 * by detecting the initial 0x80000 boundary reads and causing
34 * the buffer cache to be filled in advance.
35 */
36
37/*******************************************************************
38 sendfile wrapper that does readahead/posix_fadvise.
39*******************************************************************/
40
41static ssize_t readahead_sendfile(struct vfs_handle_struct *handle,
42                                        int tofd,
43                                        files_struct *fsp,
44                                        int fromfd,
45                                        const DATA_BLOB *header,
46                                        SMB_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(fromfd, offset, (size_t)rhd->len);
54                DEBUG(10,("readahead_sendfile: readahead on fd %u, offset %llu, len %u returned %d\n",
55                        (unsigned int)fromfd,
56                        (unsigned long long)offset,
57                        (unsigned int)rhd->len,
58                        err ));
59#elif defined(HAVE_POSIX_FADVISE)
60                int err = posix_fadvise(fromfd, 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)fromfd,
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                                        fsp,
76                                        fromfd,
77                                        header,
78                                        offset,
79                                        count);
80}
81
82/*******************************************************************
83 pread wrapper that does readahead/posix_fadvise.
84*******************************************************************/
85
86static ssize_t readahead_pread(vfs_handle_struct *handle,
87                                files_struct *fsp,
88                                int fd,
89                                void *data,
90                                size_t count,
91                                SMB_OFF_T offset)
92{
93        struct readahead_data *rhd = (struct readahead_data *)handle->data;
94
95        if ( offset % rhd->off_bound == 0) {
96#if defined(HAVE_LINUX_READAHEAD)
97                int err = readahead(fd, offset, (size_t)rhd->len);
98                DEBUG(10,("readahead_pread: readahead on fd %u, offset %llu, len %u returned %d\n",
99                        (unsigned int)fd,
100                        (unsigned long long)offset,
101                        (unsigned int)rhd->len,
102                        err ));
103#elif defined(HAVE_POSIX_FADVISE)
104                int err = posix_fadvise(fd, offset, (off_t)rhd->len, POSIX_FADV_WILLNEED);
105                DEBUG(10,("readahead_pread: posix_fadvise on fd %u, offset %llu, len %u returned %d\n",
106                        (unsigned int)fd,
107                        (unsigned long long)offset,
108                        (unsigned int)rhd->len,
109                        err ));
110#else
111                if (!rhd->didmsg) {
112                        DEBUG(0,("readahead_pread: no readahead on this platform\n"));
113                        rhd->didmsg = True;
114                }
115#endif
116        }
117        return SMB_VFS_NEXT_PREAD(handle, fsp, fd, data, count, offset);
118}
119
120/*******************************************************************
121 Directly called from main smbd when freeing handle.
122*******************************************************************/
123
124static void free_readahead_data(void **pptr)
125{
126        SAFE_FREE(*pptr);
127}
128
129/*******************************************************************
130 Allocate the handle specific data so we don't call the expensive
131 conv_str_size function for each sendfile/pread.
132*******************************************************************/
133
134static int readahead_connect(struct vfs_handle_struct *handle,
135                                const char *service,
136                                const char *user)
137{
138        struct readahead_data *rhd = SMB_MALLOC_P(struct readahead_data);
139        if (!rhd) {
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/*******************************************************************
167 Functions we're replacing.
168 We don't replace read as it isn't used from smbd to read file
169 data.
170*******************************************************************/
171
172static vfs_op_tuple readahead_ops [] =
173{
174        {SMB_VFS_OP(readahead_sendfile), SMB_VFS_OP_SENDFILE, SMB_VFS_LAYER_TRANSPARENT},
175        {SMB_VFS_OP(readahead_pread), SMB_VFS_OP_PREAD, SMB_VFS_LAYER_TRANSPARENT},
176        {SMB_VFS_OP(readahead_connect), SMB_VFS_OP_CONNECT,  SMB_VFS_LAYER_TRANSPARENT},
177        {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
178};
179
180/*******************************************************************
181 Module initialization boilerplate.
182*******************************************************************/
183
184NTSTATUS vfs_readahead_init(void);
185NTSTATUS vfs_readahead_init(void)
186{
187        return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "readahead", readahead_ops);
188}
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