2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
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8 * modification, are permitted provided that the following conditions
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34 * $DragonFly: src/sys/sys/journal.h,v 1.2 2005/03/05 05:08:30 dillon Exp $
37 #ifndef _SYS_JOURNAL_H_
38 #define _SYS_JOURNAL_H_
41 * Physical file format (binary)
43 * All raw records are 128-bit aligned, but all record sizes are actual.
44 * This means that any scanning code must 16-byte-align the recsize field
45 * when calculating skips. The top level raw record has a header and a
46 * trailer to allow both forwards and backwards scanning of the journal.
47 * The alignment requirement allows the worker thread FIFO reservation
48 * API to operate efficiently, amoung other things.
50 * Logical data stream records are usually no larger then the journal's
51 * in-memory FIFO, since the journal's transactional APIs return contiguous
52 * blocks of buffer space and since logical stream records are used to avoid
53 * stalls when concurrent blocking operations are being written to the journal.
54 * Programs can depend on a logical stream record being a 'reasonable' size.
56 * Multiple logical data streams may operate concurrently in the journal,
57 * reflecting the fact that the system may be executing multiple blocking
58 * operations on the filesystem all at the same time. These logical data
59 * streams are short-lived transactional entities which use a 13 bit id
60 * plus a transaction start bit, end bit, and abort bit.
62 * Stream identifiers in the 0x00-0xFF range are special and not used for
63 * normal transactional commands.
65 * Stream id 0x00 indicates that no other streams should be active at that
66 * point in the journal, which helps the journaling code detect corruption.
68 * Stream id 0x01 is used for pad. Pads are used to align data on convenient
69 * boundaries and to deal with dead space.
71 * Stream id 0x02 indicates a discontinuity in the streamed data and typically
72 * contains information relating to the reason for the discontinuity.
73 * JTYPE_ASSOCIATE and JTYPE_DISASSOCIATE are usually emplaced in stream 0x02.
75 * Stream id 0x03 may be used to annotate the journal with text comments
76 * via mountctl commands. This can be extremely useful to note situations
77 * that may help with later recovery or audit operations.
79 * Stream id 0x04-0x7F are reserved by DragonFly for future protocol expansion.
81 * Stream id 0x80-0xFF may be used for third-party protocol expansion.
83 * Stream id's 0x0100-0x1FFF typically represent short-lived transactions
84 * (i.e. an id may be reused once the previous use has completed). The
85 * journaling system runs through these id's sequentially which means that
86 * the journaling code can handle up to 8192-256 = 7936 simultanious
87 * transactions at any given moment.
89 * The sequence number field is context-sensitive. It is typically used by
90 * a journaling stream to provide an incrementing counter and/or timestamp
91 * so recovery utilities can determine if any data is missing.
93 * The check word in the trailer may be used to provide an integrity check
94 * on the journaled data. A value of 0 always means that no check word
95 * has been calculated.
97 * The journal_rawrecbeg structure MUST be a multiple of 16 bytes.
98 * The journal_rawrecend structure MUST be a multiple of 8 bytes.
100 * NOTE: PAD RECORD SPECIAL CASE. Pad records are 16 bytes and have the
101 * rawrecend structure overlayed on the sequence number field of the
102 * rawrecbeg structure. This is necessary because stream records are
103 * 16 byte aligned, not 24 byte aligned, and dead space is not allowed.
104 * So the pad record must fit into any dead space.
106 struct journal_rawrecbeg {
107 u_int16_t begmagic; /* recovery scan, endianess detection */
108 u_int16_t streamid; /* start/stop bits and stream identifier */
109 int32_t recsize; /* stream data block (incls beg & end) */
110 int64_t seqno; /* sequence number or transaction id */
111 /* ADDITIONAL DATA */
114 struct journal_rawrecend {
115 u_int16_t endmagic; /* recovery scan, endianess detection */
116 u_int16_t check; /* check word or 0 */
117 int32_t recsize; /* same as rawrecbeg->recsize, for rev scan */
121 * Constants for stream record magic numbers. The incomplete magic
122 * number code is used internally by the memory FIFO reservation API
123 * and worker thread, allowing a block of space in the journaling
124 * stream (aka a stream block) to be reserved and then populated without
125 * stalling other threads doing their own reservation and population.
127 #define JREC_BEGMAGIC 0x1234
128 #define JREC_ENDMAGIC 0xCDEF
129 #define JREC_INCOMPLETEMAGIC 0xFFFF
132 * Stream ids are 14 bits. The top 2 bits specify when a new logical
133 * stream is being created or an existing logical stream is being terminated.
134 * A single raw stream record will set both the BEGIN and END bits if the
135 * entire transaction is encapsulated in a single stream record.
137 #define JREC_STREAMCTL_MASK 0xE000
138 #define JREC_STREAMCTL_BEGIN 0x8000 /* start a new logical stream */
139 #define JREC_STREAMCTL_END 0x4000 /* terminate a logical stream */
140 #define JREC_STREAMCTL_ABORTED 0x2000
142 #define JREC_STREAMID_MASK 0x1FFF
143 #define JREC_STREAMID_SYNCPT (JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END|0x0000)
144 #define JREC_STREAMID_PAD (JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END|0x0001)
145 #define JREC_STREAMID_DISCONT 0x0002 /* discontinuity */
146 #define JREC_STREAMID_ANNOTATE 0x0003 /* annotation */
147 /* 0x0004-0x007F reserved by DragonFly */
148 /* 0x0080-0x00FF for third party use */
149 #define JREC_STREAMID_JMIN 0x0100 /* lowest allowed general id */
150 #define JREC_STREAMID_JMAX 0x2000 /* (one past the highest allowed id) */
152 #define JREC_DEFAULTSIZE 64 /* reasonable initial reservation */
155 * Each logical journaling stream typically represents a transaction...
156 * that is, a VFS operation. The VFS operation is written out using
157 * sub-records and may contain multiple, possibly nested sub-transactions.
158 * multiple sub-transactions occur when a VFS operation cannot be represented
159 * by a single command. This is typically the case when a journal is
160 * configured to be reversable because UNDO sequences almost always have to
161 * be specified in such cases. For example, if you ftruncate() a file the
162 * journal might have to write out a sequence of WRITE records representing
163 * the lost data, otherwise the journal would not be reversable.
164 * Sub-transactions within a particular stream do not have their own sequence
165 * number field and thus may not be parallelized (the protocol is already
168 * In order to support streaming operation with a limited buffer the recsize
169 * field is allowed to be 0 for subrecords with the JMASK_NESTED bit set.
170 * If this case occurs a scanner can determine that the recursion has ended
171 * by detecting a nested subrecord with the JMASK_LAST bit set. A scanner
172 * may also set the field to the proper value after the fact to make later
173 * operations more efficient.
175 * Note that this bit must be properly set even if the recsize field is
176 * non-zero. The recsize must always be properly specified for 'leaf'
177 * subrecords, however in order to allow subsystems to potentially allocate
178 * more data space then they use the protocol allows any 'dead' space to be
179 * filled with JLEAF_PAD records.
181 * The recsize field may indicate data well past the size of the current
182 * raw stream record. That is, the scanner may have to glue together
183 * multiple stream records with the same stream id to fully decode the
184 * embedded subrecords. In particular, a subrecord could very well represent
185 * hundreds of megabytes of data (e.g. if a program were to do a
186 * multi-megabyte write()) and be split up across thousands of raw streaming
187 * records, possibly interlaced with other unrelated streams from other
188 * unrelated processes.
190 * If a large sub-transaction is aborted the logical stream may be
191 * terminated without writing out all the expected data. When this occurs
192 * the stream's ending record must also have the JREC_STREAMCTL_ABORTED bit
193 * set. However, scanners should still be robust enough to detect such
194 * overflows even if the aborted bit is not set and consider them data
197 * Aborts may also occur in the normal course of operations, especially once
198 * the journaling API is integrated into the cache coherency API. A normal
199 * abort is issued by emplacing a JLEAF_ABORT record within the transaction
200 * being aborted. Such records must be the last record in the sub-transaction,
201 * so JLEAF_LAST is also usually set. In a transaction with many
202 * sub-transactions only those sub-transactions with an abort record are
203 * aborted, the rest remain valid. Abort records are considered S.O.P. for
204 * two reasons: First, limited memory buffer space may make it impossible
205 * to delete the portion of the stream being aborted (the data may have
206 * already been sent to the target). Second, the journaling code will
207 * eventually be used to support a cache coherency layer which may have to
208 * abort operations as part of the cache coherency protocol. Note that
209 * subrecord aborts are different from stream record aborts. Stream record
210 * aborts are considered to be extrodinary situations while subrecord aborts
214 struct journal_subrecord {
215 int16_t rectype; /* 2 control bits, 14 record type bits */
216 int16_t reserved; /* future use */
217 int32_t recsize; /* record size (mandatory if not NESTED) */
218 /* ADDITIONAL DATA */
221 #define JMASK_NESTED 0x8000 /* data is a nested recursion */
222 #define JMASK_LAST 0x4000
223 #define JMASK_SUBRECORD 0x0400
225 #define JLEAF_PAD 0x0000
226 #define JLEAF_ABORT 0x0001
227 #define JTYPE_ASSOCIATE 0x0002
228 #define JTYPE_DISASSOCIATE 0x0003
229 #define JTYPE_UNDO (JMASK_NESTED|0x0004)
230 #define JTYPE_AUDIT (JMASK_NESTED|0x0005)
232 #define JTYPE_SETATTR (JMASK_NESTED|0x0010)
233 #define JTYPE_WRITE (JMASK_NESTED|0x0011)
234 #define JTYPE_PUTPAGES (JMASK_NESTED|0x0012)
235 #define JTYPE_SETACL (JMASK_NESTED|0x0013)
236 #define JTYPE_SETEXTATTR (JMASK_NESTED|0x0014)
237 #define JTYPE_CREATE (JMASK_NESTED|0x0015)
238 #define JTYPE_MKNOD (JMASK_NESTED|0x0016)
239 #define JTYPE_LINK (JMASK_NESTED|0x0017)
240 #define JTYPE_SYMLINK (JMASK_NESTED|0x0018)
241 #define JTYPE_WHITEOUT (JMASK_NESTED|0x0019)
242 #define JTYPE_REMOVE (JMASK_NESTED|0x001A)
243 #define JTYPE_MKDIR (JMASK_NESTED|0x001B)
244 #define JTYPE_RMDIR (JMASK_NESTED|0x001C)
245 #define JTYPE_RENAME (JMASK_NESTED|0x001D)
247 #define JTYPE_VATTR (JMASK_NESTED|0x0100)
248 #define JTYPE_CRED (JMASK_NESTED|0x0101)
251 * Low level record types
253 #define JLEAF_FILEDATA 0x0401
254 #define JLEAF_PATH1 0x0402
255 #define JLEAF_PATH2 0x0403
256 #define JLEAF_PATH3 0x0404
257 #define JLEAF_PATH4 0x0405
258 #define JLEAF_UID 0x0406
259 #define JLEAF_GID 0x0407
260 #define JLEAF_MODES 0x0408
261 #define JLEAF_FFLAGS 0x0409
262 #define JLEAF_PID 0x040A
263 #define JLEAF_PPID 0x040B
264 #define JLEAF_COMM 0x040C
265 #define JLEAF_ATTRNAME 0x040D
266 #define JLEAF_PATH_REF 0x040E
267 #define JLEAF_RESERVED_0F 0x040F
268 #define JLEAF_SYMLINKDATA 0x0410
269 #define JLEAF_SEEKPOS 0x0411
270 #define JLEAF_INUM 0x0412
271 #define JLEAF_NLINK 0x0413
272 #define JLEAF_FSID 0x0414
273 #define JLEAF_SIZE 0x0415
274 #define JLEAF_ATIME 0x0416
275 #define JLEAF_MTIME 0x0417
276 #define JLEAF_CTIME 0x0418
277 #define JLEAF_GEN 0x0419
278 #define JLEAF_FLAGS 0x041A
279 #define JLEAF_UDEV 0x041B
280 #define JLEAF_FILEREV 0x041C
283 * Low level journal data file structures
285 * NOTE: embedded strings may use the full width of the field and thus
286 * may not be 0-terminated.
289 char path[4]; /* path from base of mount point */
290 /* path is variable length and 0-terminated */
296 struct timespec atime;
297 struct timespec mtime;
298 struct timespec ctime;
306 int32_t flags; /* suid/sgid and other flags */
307 char line[8]; /* ttyname or other session identification */
308 char comm[8]; /* simplified command name for reference */
311 struct jleaf_ioinfo {