sys/sys/journal.h

   1 /*
   2  * Copyright (c) 2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/sys/journal.h,v 1.10 2005/09/07 19:04:16 dillon Exp $
  35  */
  36
  37 #ifndef _SYS_JOURNAL_H_
  38 #define _SYS_JOURNAL_H_
  39
  40 /*
  41  * Physical file format (binary)
  42  *
  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.
  49  *
  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.
  55  *
  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.
  61  *
  62  * Stream identifiers in the 0x00-0xFF range are special and not used for
  63  * normal transactional commands.
  64  *
  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.
  67  *
  68  * Stream id 0x01 is used for pad.  Pads are used to align data on convenient
  69  * boundaries and to deal with dead space.
  70  *
  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.
  74  *
  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.
  78  *
  79  * Stream id 0x04-0x7F are reserved by DragonFly for future protocol expansion.
  80  *
  81  * Stream id 0x80-0xFF may be used for third-party protocol expansion.
  82  *
  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.
  88  *
  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.
  92  *
  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.
  96  *
  97  * The journal_rawrecbeg structure MUST be a multiple of 16 bytes.
  98  * The journal_rawrecend structure MUST be a multiple of 8 bytes.
  99  *
 100  * NOTE: PAD RECORD SPECIAL CASE.  Pad records can be 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.  THEREFORE, THE TRANSID
 105  * FIELD FOR A PAD RECORD MUST BE IGNORED.
 106  */
 107 struct journal_rawrecbeg {
 108         u_int16_t begmagic;     /* recovery scan, endianess detection */
 109         u_int16_t streamid;     /* start/stop bits and stream identifier */
 110         int32_t recsize;        /* stream data block (incls beg & end) */
 111         int64_t transid;        /* sequence number or transaction id */
 112         /* ADDITIONAL DATA */
 113 };
 114
 115 struct journal_rawrecend {
 116         u_int16_t endmagic;     /* recovery scan, endianess detection */
 117         u_int16_t check;        /* check word or 0 */
 118         int32_t recsize;        /* same as rawrecbeg->recsize, for rev scan */
 119 };
 120
 121 struct journal_ackrecord {
 122         struct journal_rawrecbeg        rbeg;
 123         int32_t                         filler0;
 124         int32_t                         filler1;
 125         struct journal_rawrecend        rend;
 126 };
 127
 128 /*
 129  * Constants for stream record magic numbers.    The incomplete magic
 130  * number code is used internally by the memory FIFO reservation API
 131  * and worker thread, allowing a block of space in the journaling
 132  * stream (aka a stream block) to be reserved and then populated without
 133  * stalling other threads doing their own reservation and population.
 134  */
 135 #define JREC_BEGMAGIC           0x1234
 136 #define JREC_ENDMAGIC           0xCDEF
 137 #define JREC_INCOMPLETEMAGIC    0xFFFF
 138
 139 /*
 140  * Stream ids are 14 bits.  The top 2 bits specify when a new logical
 141  * stream is being created or an existing logical stream is being terminated.
 142  * A single raw stream record will set both the BEGIN and END bits if the
 143  * entire transaction is encapsulated in a single stream record.
 144  */
 145 #define JREC_STREAMCTL_MASK     0xE000
 146 #define JREC_STREAMCTL_BEGIN    0x8000  /* start a new logical stream */
 147 #define JREC_STREAMCTL_END      0x4000  /* terminate a logical stream */
 148 #define JREC_STREAMCTL_ABORTED  0x2000
 149
 150 #define JREC_STREAMID_MASK      0x1FFF
 151 #define JREC_STREAMID_SYNCPT    (JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END|0x0000)
 152 #define JREC_STREAMID_PAD       (JREC_STREAMCTL_BEGIN|JREC_STREAMCTL_END|0x0001)
 153 #define JREC_STREAMID_DISCONT   0x0002  /* discontinuity */
 154 #define JREC_STREAMID_ANNOTATE  0x0003  /* annotation */
 155 #define JREC_STREAMID_ACK       0x0004  /* acknowledgement */
 156 #define JREC_STREAMID_RESTART   0x0005  /* disctoninuity - journal restart */
 157                                 /* 0x0006-0x007F reserved by DragonFly */
 158                                 /* 0x0080-0x00FF for third party use */
 159 #define JREC_STREAMID_JMIN      0x0100  /* lowest allowed general id */
 160 #define JREC_STREAMID_JMAX      0x2000  /* (one past the highest allowed id) */
 161
 162 #define JREC_DEFAULTSIZE        64      /* reasonable initial reservation */
 163 #define JREC_MINRECSIZE         16      /* (after alignment) */
 164 #define JREC_MAXRECSIZE         (128*1024*1024)
 165
 166 /*
 167  * Each logical journaling stream typically represents a transaction...
 168  * that is, a VFS operation.  The VFS operation is written out using
 169  * sub-records and may contain multiple, possibly nested sub-transactions.
 170  * multiple sub-transactions occur when a VFS operation cannot be represented
 171  * by a single command.  This is typically the case when a journal is
 172  * configured to be reversable because UNDO sequences almost always have to
 173  * be specified in such cases.  For example, if you ftruncate() a file the
 174  * journal might have to write out a sequence of WRITE records representing
 175  * the lost data, otherwise the journal would not be reversable.
 176  * Sub-transactions within a particular stream do not have their own sequence
 177  * number field and thus may not be parallelized (the protocol is already
 178  * complex enough!).
 179  *
 180  * In order to support streaming operation with a limited buffer the recsize
 181  * field is allowed to be 0 for subrecords with the JMASK_NESTED bit set.
 182  * If this case occurs a scanner can determine that the recursion has ended
 183  * by detecting a nested subrecord with the JMASK_LAST bit set.  A scanner
 184  * may also set the field to the proper value after the fact to make later
 185  * operations more efficient.
 186  *
 187  * Note that this bit must be properly set even if the recsize field is
 188  * non-zero.  The recsize must always be properly specified for 'leaf'
 189  * subrecords, however in order to allow subsystems to potentially allocate
 190  * more data space then they use the protocol allows any 'dead' space to be
 191  * filled with JLEAF_PAD records.
 192  *
 193  * The recsize field may indicate data well past the size of the current
 194  * raw stream record.  That is, the scanner may have to glue together
 195  * multiple stream records with the same stream id to fully decode the
 196  * embedded subrecords.  In particular, a subrecord could very well represent
 197  * hundreds of megabytes of data (e.g. if a program were to do a
 198  * multi-megabyte write()) and be split up across thousands of raw streaming
 199  * records, possibly interlaced with other unrelated streams from other
 200  * unrelated processes.
 201  *
 202  * If a large sub-transaction is aborted the logical stream may be
 203  * terminated without writing out all the expected data.  When this occurs
 204  * the stream's ending record must also have the JREC_STREAMCTL_ABORTED bit
 205  * set.  However, scanners should still be robust enough to detect such
 206  * overflows even if the aborted bit is not set and consider them data
 207  * corruption.
 208  *
 209  * Aborts may also occur in the normal course of operations, especially once
 210  * the journaling API is integrated into the cache coherency API.  A normal
 211  * abort is issued by emplacing a JLEAF_ABORT record within the transaction
 212  * being aborted.  Such records must be the last record in the sub-transaction,
 213  * so JLEAF_LAST is also usually set.  In a transaction with many
 214  * sub-transactions only those sub-transactions with an abort record are
 215  * aborted, the rest remain valid.  Abort records are considered S.O.P. for
 216  * two reasons:  First, limited memory buffer space may make it impossible
 217  * to delete the portion of the stream being aborted (the data may have
 218  * already been sent to the target).  Second, the journaling code will
 219  * eventually be used to support a cache coherency layer which may have to
 220  * abort operations as part of the cache coherency protocol.  Note that
 221  * subrecord aborts are different from stream record aborts.  Stream record
 222  * aborts are considered to be extrodinary situations while subrecord aborts
 223  * are S.O.P.
 224  */
 225
 226 struct journal_subrecord {
 227         u_int16_t rectype;      /* 2 control bits, 14 record type bits */
 228         int16_t reserved;       /* future use */
 229         int32_t recsize;        /* record size (mandatory if not NESTED) */
 230         /* ADDITIONAL DATA */
 231 };
 232
 233 #define JMASK_NESTED            0x8000  /* data is a nested recursion */
 234 #define JMASK_LAST              0x4000
 235 #define JMASK_SUBRECORD         0x0400
 236 #define JTYPE_MASK              (~JMASK_LAST)
 237
 238 #define JLEAF_PAD               0x0000
 239 #define JLEAF_ABORT             0x0001
 240 #define JTYPE_ASSOCIATE         0x0002
 241 #define JTYPE_DISASSOCIATE      0x0003
 242 #define JTYPE_UNDO              (JMASK_NESTED|0x0004)
 243 #define JTYPE_AUDIT             (JMASK_NESTED|0x0005)
 244 #define JTYPE_REDO              (JMASK_NESTED|0x0006)
 245
 246 #define JTYPE_SETATTR           (JMASK_NESTED|0x0010)
 247 #define JTYPE_WRITE             (JMASK_NESTED|0x0011)
 248 #define JTYPE_PUTPAGES          (JMASK_NESTED|0x0012)
 249 #define JTYPE_SETACL            (JMASK_NESTED|0x0013)
 250 #define JTYPE_SETEXTATTR        (JMASK_NESTED|0x0014)
 251 #define JTYPE_CREATE            (JMASK_NESTED|0x0015)
 252 #define JTYPE_MKNOD             (JMASK_NESTED|0x0016)
 253 #define JTYPE_LINK              (JMASK_NESTED|0x0017)
 254 #define JTYPE_SYMLINK           (JMASK_NESTED|0x0018)
 255 #define JTYPE_WHITEOUT          (JMASK_NESTED|0x0019)
 256 #define JTYPE_REMOVE            (JMASK_NESTED|0x001A)
 257 #define JTYPE_MKDIR             (JMASK_NESTED|0x001B)
 258 #define JTYPE_RMDIR             (JMASK_NESTED|0x001C)
 259 #define JTYPE_RENAME            (JMASK_NESTED|0x001D)
 260
 261 #define JTYPE_VATTR             (JMASK_NESTED|0x0100)
 262 #define JTYPE_CRED              (JMASK_NESTED|0x0101)
 263
 264 /*
 265  * Low level record types
 266  */
 267 #define JLEAF_FILEDATA          0x0401
 268 #define JLEAF_PATH1             0x0402
 269 #define JLEAF_PATH2             0x0403
 270 #define JLEAF_PATH3             0x0404
 271 #define JLEAF_PATH4             0x0405
 272 #define JLEAF_UID               0x0406
 273 #define JLEAF_GID               0x0407
 274 #define JLEAF_MODES             0x0408
 275 #define JLEAF_FFLAGS            0x0409
 276 #define JLEAF_PID               0x040A
 277 #define JLEAF_PPID              0x040B
 278 #define JLEAF_COMM              0x040C
 279 #define JLEAF_ATTRNAME          0x040D
 280 #define JLEAF_PATH_REF          0x040E
 281 #define JLEAF_RESERVED_0F       0x040F
 282 #define JLEAF_SYMLINKDATA       0x0410
 283 #define JLEAF_SEEKPOS           0x0411
 284 #define JLEAF_INUM              0x0412
 285 #define JLEAF_NLINK             0x0413
 286 #define JLEAF_FSID              0x0414
 287 #define JLEAF_SIZE              0x0415
 288 #define JLEAF_ATIME             0x0416
 289 #define JLEAF_MTIME             0x0417
 290 #define JLEAF_CTIME             0x0418
 291 #define JLEAF_GEN               0x0419
 292 #define JLEAF_FLAGS             0x041A
 293 #define JLEAF_UDEV              0x041B
 294 #define JLEAF_FILEREV           0x041C
 295 #define JLEAF_VTYPE             0x041D
 296 #define JLEAF_ERROR             0x041E
 297
 298 /*
 299  * Low level journal data file structures
 300  *
 301  * NOTE: embedded strings may use the full width of the field and thus
 302  * may not be 0-terminated.
 303  */
 304 struct jleaf_path {
 305         char    path[4];        /* path from base of mount point */
 306         /* path is variable length and 0-terminated */
 307 };
 308
 309 struct jleaf_vattr {
 310         int32_t modes;
 311         int32_t fflags;
 312         struct timespec atime;
 313         struct timespec mtime;
 314         struct timespec ctime;
 315         int64_t inum;
 316 };
 317
 318 struct jleaf_cred {
 319         int32_t uid;
 320         int32_t gid;
 321         int32_t pid;
 322         int32_t flags;          /* suid/sgid and other flags */
 323         char    line[8];        /* ttyname or other session identification */
 324         char    comm[8];        /* simplified command name for reference */
 325 };
 326
 327 struct jleaf_ioinfo {
 328         int64_t offset;
 329 };
 330
 331 #endif