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-rw-r--r--Documentation/DocBook/Makefile2
-rw-r--r--Documentation/DocBook/filesystems.tmpl (renamed from Documentation/DocBook/journal-api.tmpl)252
-rw-r--r--Documentation/DocBook/kernel-api.tmpl60
3 files changed, 161 insertions, 153 deletions
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index 66e1cf733571..db9499adbed4 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -9,7 +9,7 @@
9DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \ 9DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \
10 kernel-hacking.xml kernel-locking.xml deviceiobook.xml \ 10 kernel-hacking.xml kernel-locking.xml deviceiobook.xml \
11 procfs-guide.xml writing_usb_driver.xml \ 11 procfs-guide.xml writing_usb_driver.xml \
12 kernel-api.xml journal-api.xml lsm.xml usb.xml \ 12 kernel-api.xml filesystems.xml lsm.xml usb.xml \
13 gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \ 13 gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
14 genericirq.xml 14 genericirq.xml
15 15
diff --git a/Documentation/DocBook/journal-api.tmpl b/Documentation/DocBook/filesystems.tmpl
index 2077f9a28c19..39fa2aba7f9b 100644
--- a/Documentation/DocBook/journal-api.tmpl
+++ b/Documentation/DocBook/filesystems.tmpl
@@ -2,39 +2,11 @@
2<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" 2<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> 3 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
4 4
5<book id="LinuxJBDAPI"> 5<book id="Linux-filesystems-API">
6 <bookinfo> 6 <bookinfo>
7 <title>The Linux Journalling API</title> 7 <title>Linux Filesystems API</title>
8 <authorgroup>
9 <author>
10 <firstname>Roger</firstname>
11 <surname>Gammans</surname>
12 <affiliation>
13 <address>
14 <email>rgammans@computer-surgery.co.uk</email>
15 </address>
16 </affiliation>
17 </author>
18 </authorgroup>
19
20 <authorgroup>
21 <author>
22 <firstname>Stephen</firstname>
23 <surname>Tweedie</surname>
24 <affiliation>
25 <address>
26 <email>sct@redhat.com</email>
27 </address>
28 </affiliation>
29 </author>
30 </authorgroup>
31 8
32 <copyright> 9 <legalnotice>
33 <year>2002</year>
34 <holder>Roger Gammans</holder>
35 </copyright>
36
37<legalnotice>
38 <para> 10 <para>
39 This documentation is free software; you can redistribute 11 This documentation is free software; you can redistribute
40 it and/or modify it under the terms of the GNU General Public 12 it and/or modify it under the terms of the GNU General Public
@@ -42,21 +14,21 @@
42 version 2 of the License, or (at your option) any later 14 version 2 of the License, or (at your option) any later
43 version. 15 version.
44 </para> 16 </para>
45 17
46 <para> 18 <para>
47 This program is distributed in the hope that it will be 19 This program is distributed in the hope that it will be
48 useful, but WITHOUT ANY WARRANTY; without even the implied 20 useful, but WITHOUT ANY WARRANTY; without even the implied
49 warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 21 warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
50 See the GNU General Public License for more details. 22 See the GNU General Public License for more details.
51 </para> 23 </para>
52 24
53 <para> 25 <para>
54 You should have received a copy of the GNU General Public 26 You should have received a copy of the GNU General Public
55 License along with this program; if not, write to the Free 27 License along with this program; if not, write to the Free
56 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, 28 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
57 MA 02111-1307 USA 29 MA 02111-1307 USA
58 </para> 30 </para>
59 31
60 <para> 32 <para>
61 For more details see the file COPYING in the source 33 For more details see the file COPYING in the source
62 distribution of Linux. 34 distribution of Linux.
@@ -66,17 +38,113 @@
66 38
67<toc></toc> 39<toc></toc>
68 40
69 <chapter id="Overview"> 41 <chapter id="vfs">
42 <title>The Linux VFS</title>
43 <sect1><title>The Filesystem types</title>
44!Iinclude/linux/fs.h
45 </sect1>
46 <sect1><title>The Directory Cache</title>
47!Efs/dcache.c
48!Iinclude/linux/dcache.h
49 </sect1>
50 <sect1><title>Inode Handling</title>
51!Efs/inode.c
52!Efs/bad_inode.c
53 </sect1>
54 <sect1><title>Registration and Superblocks</title>
55!Efs/super.c
56 </sect1>
57 <sect1><title>File Locks</title>
58!Efs/locks.c
59!Ifs/locks.c
60 </sect1>
61 <sect1><title>Other Functions</title>
62!Efs/mpage.c
63!Efs/namei.c
64!Efs/buffer.c
65!Efs/bio.c
66!Efs/seq_file.c
67!Efs/filesystems.c
68!Efs/fs-writeback.c
69!Efs/block_dev.c
70 </sect1>
71 </chapter>
72
73 <chapter id="proc">
74 <title>The proc filesystem</title>
75
76 <sect1><title>sysctl interface</title>
77!Ekernel/sysctl.c
78 </sect1>
79
80 <sect1><title>proc filesystem interface</title>
81!Ifs/proc/base.c
82 </sect1>
83 </chapter>
84
85 <chapter id="sysfs">
86 <title>The Filesystem for Exporting Kernel Objects</title>
87!Efs/sysfs/file.c
88!Efs/sysfs/symlink.c
89!Efs/sysfs/bin.c
90 </chapter>
91
92 <chapter id="debugfs">
93 <title>The debugfs filesystem</title>
94
95 <sect1><title>debugfs interface</title>
96!Efs/debugfs/inode.c
97!Efs/debugfs/file.c
98 </sect1>
99 </chapter>
100
101 <chapter id="LinuxJDBAPI">
102 <chapterinfo>
103 <title>The Linux Journalling API</title>
104
105 <authorgroup>
106 <author>
107 <firstname>Roger</firstname>
108 <surname>Gammans</surname>
109 <affiliation>
110 <address>
111 <email>rgammans@computer-surgery.co.uk</email>
112 </address>
113 </affiliation>
114 </author>
115 </authorgroup>
116
117 <authorgroup>
118 <author>
119 <firstname>Stephen</firstname>
120 <surname>Tweedie</surname>
121 <affiliation>
122 <address>
123 <email>sct@redhat.com</email>
124 </address>
125 </affiliation>
126 </author>
127 </authorgroup>
128
129 <copyright>
130 <year>2002</year>
131 <holder>Roger Gammans</holder>
132 </copyright>
133 </chapterinfo>
134
135 <title>The Linux Journalling API</title>
136
137 <sect1>
70 <title>Overview</title> 138 <title>Overview</title>
71 <sect1> 139 <sect2>
72 <title>Details</title> 140 <title>Details</title>
73<para> 141<para>
74The journalling layer is easy to use. You need to 142The journalling layer is easy to use. You need to
75first of all create a journal_t data structure. There are 143first of all create a journal_t data structure. There are
76two calls to do this dependent on how you decide to allocate the physical 144two calls to do this dependent on how you decide to allocate the physical
77media on which the journal resides. The journal_init_inode() call 145media on which the journal resides. The journal_init_inode() call
78is for journals stored in filesystem inodes, or the journal_init_dev() 146is for journals stored in filesystem inodes, or the journal_init_dev()
79call can be use for journal stored on a raw device (in a continuous range 147call can be use for journal stored on a raw device (in a continuous range
80of blocks). A journal_t is a typedef for a struct pointer, so when 148of blocks). A journal_t is a typedef for a struct pointer, so when
81you are finally finished make sure you call journal_destroy() on it 149you are finally finished make sure you call journal_destroy() on it
82to free up any used kernel memory. 150to free up any used kernel memory.
@@ -91,27 +159,26 @@ need to call journal_create().
91<para> 159<para>
92Most of the time however your journal file will already have been created, but 160Most of the time however your journal file will already have been created, but
93before you load it you must call journal_wipe() to empty the journal file. 161before you load it you must call journal_wipe() to empty the journal file.
94Hang on, you say , what if the filesystem wasn't cleanly umount()'d . Well, it is the 162Hang on, you say , what if the filesystem wasn't cleanly umount()'d . Well, it is the
95job of the client file system to detect this and skip the call to journal_wipe(). 163job of the client file system to detect this and skip the call to journal_wipe().
96</para> 164</para>
97 165
98<para> 166<para>
99In either case the next call should be to journal_load() which prepares the 167In either case the next call should be to journal_load() which prepares the
100journal file for use. Note that journal_wipe(..,0) calls journal_skip_recovery() 168journal file for use. Note that journal_wipe(..,0) calls journal_skip_recovery()
101for you if it detects any outstanding transactions in the journal and similarly 169for you if it detects any outstanding transactions in the journal and similarly
102journal_load() will call journal_recover() if necessary. 170journal_load() will call journal_recover() if necessary.
103I would advise reading fs/ext3/super.c for examples on this stage. 171I would advise reading fs/ext3/super.c for examples on this stage.
104[RGG: Why is the journal_wipe() call necessary - doesn't this needlessly 172[RGG: Why is the journal_wipe() call necessary - doesn't this needlessly
105complicate the API. Or isn't a good idea for the journal layer to hide 173complicate the API. Or isn't a good idea for the journal layer to hide
106dirty mounts from the client fs] 174dirty mounts from the client fs]
107</para> 175</para>
108 176
109<para> 177<para>
110Now you can go ahead and start modifying the underlying 178Now you can go ahead and start modifying the underlying
111filesystem. Almost. 179filesystem. Almost.
112</para> 180</para>
113 181
114
115<para> 182<para>
116 183
117You still need to actually journal your filesystem changes, this 184You still need to actually journal your filesystem changes, this
@@ -138,10 +205,10 @@ individual buffers (blocks). Before you start to modify a buffer you
138need to call journal_get_{create,write,undo}_access() as appropriate, 205need to call journal_get_{create,write,undo}_access() as appropriate,
139this allows the journalling layer to copy the unmodified data if it 206this allows the journalling layer to copy the unmodified data if it
140needs to. After all the buffer may be part of a previously uncommitted 207needs to. After all the buffer may be part of a previously uncommitted
141transaction. 208transaction.
142At this point you are at last ready to modify a buffer, and once 209At this point you are at last ready to modify a buffer, and once
143you are have done so you need to call journal_dirty_{meta,}data(). 210you are have done so you need to call journal_dirty_{meta,}data().
144Or if you've asked for access to a buffer you now know is now longer 211Or if you've asked for access to a buffer you now know is now longer
145required to be pushed back on the device you can call journal_forget() 212required to be pushed back on the device you can call journal_forget()
146in much the same way as you might have used bforget() in the past. 213in much the same way as you might have used bforget() in the past.
147</para> 214</para>
@@ -156,7 +223,6 @@ Then at umount time , in your put_super() (2.4) or write_super() (2.5)
156you can then call journal_destroy() to clean up your in-core journal object. 223you can then call journal_destroy() to clean up your in-core journal object.
157</para> 224</para>
158 225
159
160<para> 226<para>
161Unfortunately there a couple of ways the journal layer can cause a deadlock. 227Unfortunately there a couple of ways the journal layer can cause a deadlock.
162The first thing to note is that each task can only have 228The first thing to note is that each task can only have
@@ -164,19 +230,19 @@ a single outstanding transaction at any one time, remember nothing
164commits until the outermost journal_stop(). This means 230commits until the outermost journal_stop(). This means
165you must complete the transaction at the end of each file/inode/address 231you must complete the transaction at the end of each file/inode/address
166etc. operation you perform, so that the journalling system isn't re-entered 232etc. operation you perform, so that the journalling system isn't re-entered
167on another journal. Since transactions can't be nested/batched 233on another journal. Since transactions can't be nested/batched
168across differing journals, and another filesystem other than 234across differing journals, and another filesystem other than
169yours (say ext3) may be modified in a later syscall. 235yours (say ext3) may be modified in a later syscall.
170</para> 236</para>
171 237
172<para> 238<para>
173The second case to bear in mind is that journal_start() can 239The second case to bear in mind is that journal_start() can
174block if there isn't enough space in the journal for your transaction 240block if there isn't enough space in the journal for your transaction
175(based on the passed nblocks param) - when it blocks it merely(!) needs to 241(based on the passed nblocks param) - when it blocks it merely(!) needs to
176wait for transactions to complete and be committed from other tasks, 242wait for transactions to complete and be committed from other tasks,
177so essentially we are waiting for journal_stop(). So to avoid 243so essentially we are waiting for journal_stop(). So to avoid
178deadlocks you must treat journal_start/stop() as if they 244deadlocks you must treat journal_start/stop() as if they
179were semaphores and include them in your semaphore ordering rules to prevent 245were semaphores and include them in your semaphore ordering rules to prevent
180deadlocks. Note that journal_extend() has similar blocking behaviour to 246deadlocks. Note that journal_extend() has similar blocking behaviour to
181journal_start() so you can deadlock here just as easily as on journal_start(). 247journal_start() so you can deadlock here just as easily as on journal_start().
182</para> 248</para>
@@ -184,7 +250,7 @@ journal_start() so you can deadlock here just as easily as on journal_start().
184<para> 250<para>
185Try to reserve the right number of blocks the first time. ;-). This will 251Try to reserve the right number of blocks the first time. ;-). This will
186be the maximum number of blocks you are going to touch in this transaction. 252be the maximum number of blocks you are going to touch in this transaction.
187I advise having a look at at least ext3_jbd.h to see the basis on which 253I advise having a look at at least ext3_jbd.h to see the basis on which
188ext3 uses to make these decisions. 254ext3 uses to make these decisions.
189</para> 255</para>
190 256
@@ -193,13 +259,13 @@ Another wriggle to watch out for is your on-disk block allocation strategy.
193why? Because, if you undo a delete, you need to ensure you haven't reused any 259why? Because, if you undo a delete, you need to ensure you haven't reused any
194of the freed blocks in a later transaction. One simple way of doing this 260of the freed blocks in a later transaction. One simple way of doing this
195is make sure any blocks you allocate only have checkpointed transactions 261is make sure any blocks you allocate only have checkpointed transactions
196listed against them. Ext3 does this in ext3_test_allocatable(). 262listed against them. Ext3 does this in ext3_test_allocatable().
197</para> 263</para>
198 264
199<para> 265<para>
200Lock is also providing through journal_{un,}lock_updates(), 266Lock is also providing through journal_{un,}lock_updates(),
201ext3 uses this when it wants a window with a clean and stable fs for a moment. 267ext3 uses this when it wants a window with a clean and stable fs for a moment.
202eg. 268eg.
203</para> 269</para>
204 270
205<programlisting> 271<programlisting>
@@ -230,19 +296,19 @@ extend it like this:-
230 struct journal_callback for_jbd; 296 struct journal_callback for_jbd;
231 // Stuff for myfs allocated together. 297 // Stuff for myfs allocated together.
232 myfs_inode* i_commited; 298 myfs_inode* i_commited;
233 299
234 } 300 }
235</programlisting> 301</programlisting>
236 302
237<para> 303<para>
238this would be useful if you needed to know when data was committed to a 304this would be useful if you needed to know when data was committed to a
239particular inode. 305particular inode.
240</para> 306</para>
241 307
242</sect1> 308 </sect2>
243 309
244<sect1> 310 <sect2>
245<title>Summary</title> 311 <title>Summary</title>
246<para> 312<para>
247Using the journal is a matter of wrapping the different context changes, 313Using the journal is a matter of wrapping the different context changes,
248being each mount, each modification (transaction) and each changed buffer 314being each mount, each modification (transaction) and each changed buffer
@@ -260,15 +326,15 @@ an example.
260 if (clean) journal_wipe(); 326 if (clean) journal_wipe();
261 journal_load(); 327 journal_load();
262 328
263 foreach(transaction) { /*transactions must be 329 foreach(transaction) { /*transactions must be
264 completed before 330 completed before
265 a syscall returns to 331 a syscall returns to
266 userspace*/ 332 userspace*/
267 333
268 handle_t * xct=journal_start(my_jnrl); 334 handle_t * xct=journal_start(my_jnrl);
269 foreach(bh) { 335 foreach(bh) {
270 journal_get_{create,write,undo}_access(xact,bh); 336 journal_get_{create,write,undo}_access(xact,bh);
271 if ( myfs_modify(bh) ) { /* returns true 337 if ( myfs_modify(bh) ) { /* returns true
272 if makes changes */ 338 if makes changes */
273 journal_dirty_{meta,}data(xact,bh); 339 journal_dirty_{meta,}data(xact,bh);
274 } else { 340 } else {
@@ -279,55 +345,57 @@ an example.
279 } 345 }
280 journal_destroy(my_jrnl); 346 journal_destroy(my_jrnl);
281</programlisting> 347</programlisting>
282</sect1> 348 </sect2>
283 349
284</chapter> 350 </sect1>
285 351
286 <chapter id="adt"> 352 <sect1>
287 <title>Data Types</title> 353 <title>Data Types</title>
288 <para> 354 <para>
289 The journalling layer uses typedefs to 'hide' the concrete definitions 355 The journalling layer uses typedefs to 'hide' the concrete definitions
290 of the structures used. As a client of the JBD layer you can 356 of the structures used. As a client of the JBD layer you can
291 just rely on the using the pointer as a magic cookie of some sort. 357 just rely on the using the pointer as a magic cookie of some sort.
292 358
293 Obviously the hiding is not enforced as this is 'C'. 359 Obviously the hiding is not enforced as this is 'C'.
294 </para> 360 </para>
295 <sect1><title>Structures</title> 361 <sect2><title>Structures</title>
296!Iinclude/linux/jbd.h 362!Iinclude/linux/jbd.h
297 </sect1> 363 </sect2>
298</chapter> 364 </sect1>
299 365
300 <chapter id="calls"> 366 <sect1>
301 <title>Functions</title> 367 <title>Functions</title>
302 <para> 368 <para>
303 The functions here are split into two groups those that 369 The functions here are split into two groups those that
304 affect a journal as a whole, and those which are used to 370 affect a journal as a whole, and those which are used to
305 manage transactions 371 manage transactions
306</para> 372 </para>
307 <sect1><title>Journal Level</title> 373 <sect2><title>Journal Level</title>
308!Efs/jbd/journal.c 374!Efs/jbd/journal.c
309!Ifs/jbd/recovery.c 375!Ifs/jbd/recovery.c
310 </sect1> 376 </sect2>
311 <sect1><title>Transasction Level</title> 377 <sect2><title>Transasction Level</title>
312!Efs/jbd/transaction.c 378!Efs/jbd/transaction.c
313 </sect1> 379 </sect2>
314</chapter> 380 </sect1>
315<chapter> 381 <sect1>
316 <title>See also</title> 382 <title>See also</title>
317 <para> 383 <para>
318 <citation> 384 <citation>
319 <ulink url="ftp://ftp.uk.linux.org/pub/linux/sct/fs/jfs/journal-design.ps.gz"> 385 <ulink url="ftp://ftp.uk.linux.org/pub/linux/sct/fs/jfs/journal-design.ps.gz">
320 Journaling the Linux ext2fs Filesystem,LinuxExpo 98, Stephen Tweedie 386 Journaling the Linux ext2fs Filesystem, LinuxExpo 98, Stephen Tweedie
321 </ulink> 387 </ulink>
322 </citation> 388 </citation>
323 </para> 389 </para>
324 <para> 390 <para>
325 <citation> 391 <citation>
326 <ulink url="http://olstrans.sourceforge.net/release/OLS2000-ext3/OLS2000-ext3.html"> 392 <ulink url="http://olstrans.sourceforge.net/release/OLS2000-ext3/OLS2000-ext3.html">
327 Ext3 Journalling FileSystem , OLS 2000, Dr. Stephen Tweedie 393 Ext3 Journalling FileSystem, OLS 2000, Dr. Stephen Tweedie
328 </ulink> 394 </ulink>
329 </citation> 395 </citation>
330 </para> 396 </para>
331</chapter> 397 </sect1>
398
399 </chapter>
332 400
333</book> 401</book>
diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl
index 2b5ac604948c..a166675c4303 100644
--- a/Documentation/DocBook/kernel-api.tmpl
+++ b/Documentation/DocBook/kernel-api.tmpl
@@ -182,66 +182,6 @@ X!Ilib/string.c
182 </sect1> 182 </sect1>
183 </chapter> 183 </chapter>
184 184
185 <chapter id="vfs">
186 <title>The Linux VFS</title>
187 <sect1><title>The Filesystem types</title>
188!Iinclude/linux/fs.h
189 </sect1>
190 <sect1><title>The Directory Cache</title>
191!Efs/dcache.c
192!Iinclude/linux/dcache.h
193 </sect1>
194 <sect1><title>Inode Handling</title>
195!Efs/inode.c
196!Efs/bad_inode.c
197 </sect1>
198 <sect1><title>Registration and Superblocks</title>
199!Efs/super.c
200 </sect1>
201 <sect1><title>File Locks</title>
202!Efs/locks.c
203!Ifs/locks.c
204 </sect1>
205 <sect1><title>Other Functions</title>
206!Efs/mpage.c
207!Efs/namei.c
208!Efs/buffer.c
209!Efs/bio.c
210!Efs/seq_file.c
211!Efs/filesystems.c
212!Efs/fs-writeback.c
213!Efs/block_dev.c
214 </sect1>
215 </chapter>
216
217 <chapter id="proc">
218 <title>The proc filesystem</title>
219
220 <sect1><title>sysctl interface</title>
221!Ekernel/sysctl.c
222 </sect1>
223
224 <sect1><title>proc filesystem interface</title>
225!Ifs/proc/base.c
226 </sect1>
227 </chapter>
228
229 <chapter id="sysfs">
230 <title>The Filesystem for Exporting Kernel Objects</title>
231!Efs/sysfs/file.c
232!Efs/sysfs/symlink.c
233!Efs/sysfs/bin.c
234 </chapter>
235
236 <chapter id="debugfs">
237 <title>The debugfs filesystem</title>
238
239 <sect1><title>debugfs interface</title>
240!Efs/debugfs/inode.c
241!Efs/debugfs/file.c
242 </sect1>
243 </chapter>
244
245 <chapter id="relayfs"> 185 <chapter id="relayfs">
246 <title>relay interface support</title> 186 <title>relay interface support</title>
247 187