include/linux/jbd.h

   1 /*
   2  * linux/include/linux/jbd.h
   3  *
   4  * Written by Stephen C. Tweedie <sct@redhat.com>
   5  *
   6  * Copyright 1998-2000 Red Hat, Inc --- All Rights Reserved
   7  *
   8  * This file is part of the Linux kernel and is made available under
   9  * the terms of the GNU General Public License, version 2, or at your
  10  * option, any later version, incorporated herein by reference.
  11  *
  12  * Definitions for transaction data structures for the buffer cache
  13  * filesystem journaling support.
  14  */
  15
  16 #ifndef _LINUX_JBD_H
  17 #define _LINUX_JBD_H
  18
  19 /* Allow this file to be included directly into e2fsprogs */
  20 #ifndef __KERNEL__
  21 #include "jfs_compat.h"
  22 #define JFS_DEBUG
  23 #define jfs_debug jbd_debug
  24 #else
  25
  26 #include <linux/types.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/journal-head.h>
  29 #include <linux/stddef.h>
  30 #include <linux/bit_spinlock.h>
  31 #include <linux/mutex.h>
  32 #include <linux/timer.h>
  33 #include <linux/lockdep.h>
  34 #include <linux/slab.h>
  35
  36 #define journal_oom_retry 1
  37
  38 /*
  39  * Define JBD_PARANOID_IOFAIL to cause a kernel BUG() if ext3 finds
  40  * certain classes of error which can occur due to failed IOs.  Under
  41  * normal use we want ext3 to continue after such errors, because
  42  * hardware _can_ fail, but for debugging purposes when running tests on
  43  * known-good hardware we may want to trap these errors.
  44  */
  45 #undef JBD_PARANOID_IOFAIL
  46
  47 /*
  48  * The default maximum commit age, in seconds.
  49  */
  50 #define JBD_DEFAULT_MAX_COMMIT_AGE 5
  51
  52 #ifdef CONFIG_JBD_DEBUG
  53 /*
  54  * Define JBD_EXPENSIVE_CHECKING to enable more expensive internal
  55  * consistency checks.  By default we don't do this unless
  56  * CONFIG_JBD_DEBUG is on.
  57  */
  58 #define JBD_EXPENSIVE_CHECKING
  59 extern u8 journal_enable_debug;
  60
  61 #define jbd_debug(n, f, a...)                                           \
  62         do {                                                            \
  63                 if ((n) <= journal_enable_debug) {                      \
  64                         printk (KERN_DEBUG "(%s, %d): %s: ",            \
  65                                 __FILE__, __LINE__, __func__);  \
  66                         printk (f, ## a);                               \
  67                 }                                                       \
  68         } while (0)
  69 #else
  70 #define jbd_debug(f, a...)      /**/
  71 #endif
  72
  73 static inline void *jbd_alloc(size_t size, gfp_t flags)
  74 {
  75         return (void *)__get_free_pages(flags, get_order(size));
  76 }
  77
  78 static inline void jbd_free(void *ptr, size_t size)
  79 {
  80         free_pages((unsigned long)ptr, get_order(size));
  81 };
  82
  83 #define JFS_MIN_JOURNAL_BLOCKS 1024
  84
  85
  86 /**
  87  * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.
  88  *
  89  * All filesystem modifications made by the process go
  90  * through this handle.  Recursive operations (such as quota operations)
  91  * are gathered into a single update.
  92  *
  93  * The buffer credits field is used to account for journaled buffers
  94  * being modified by the running process.  To ensure that there is
  95  * enough log space for all outstanding operations, we need to limit the
  96  * number of outstanding buffers possible at any time.  When the
  97  * operation completes, any buffer credits not used are credited back to
  98  * the transaction, so that at all times we know how many buffers the
  99  * outstanding updates on a transaction might possibly touch.
 100  *
 101  * This is an opaque datatype.
 102  **/
 103 typedef struct handle_s         handle_t;       /* Atomic operation type */
 104
 105
 106 /**
 107  * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.
 108  *
 109  * journal_t is linked to from the fs superblock structure.
 110  *
 111  * We use the journal_t to keep track of all outstanding transaction
 112  * activity on the filesystem, and to manage the state of the log
 113  * writing process.
 114  *
 115  * This is an opaque datatype.
 116  **/
 117 typedef struct journal_s        journal_t;      /* Journal control structure */
 118 #endif
 119
 120 /*
 121  * Internal structures used by the logging mechanism:
 122  */
 123
 124 #define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
 125
 126 /*
 127  * On-disk structures
 128  */
 129
 130 /*
 131  * Descriptor block types:
 132  */
 133
 134 #define JFS_DESCRIPTOR_BLOCK    1
 135 #define JFS_COMMIT_BLOCK        2
 136 #define JFS_SUPERBLOCK_V1       3
 137 #define JFS_SUPERBLOCK_V2       4
 138 #define JFS_REVOKE_BLOCK        5
 139
 140 /*
 141  * Standard header for all descriptor blocks:
 142  */
 143 typedef struct journal_header_s
 144 {
 145         __be32          h_magic;
 146         __be32          h_blocktype;
 147         __be32          h_sequence;
 148 } journal_header_t;
 149
 150
 151 /*
 152  * The block tag: used to describe a single buffer in the journal
 153  */
 154 typedef struct journal_block_tag_s
 155 {
 156         __be32          t_blocknr;      /* The on-disk block number */
 157         __be32          t_flags;        /* See below */
 158 } journal_block_tag_t;
 159
 160 /*
 161  * The revoke descriptor: used on disk to describe a series of blocks to
 162  * be revoked from the log
 163  */
 164 typedef struct journal_revoke_header_s
 165 {
 166         journal_header_t r_header;
 167         __be32           r_count;       /* Count of bytes used in the block */
 168 } journal_revoke_header_t;
 169
 170
 171 /* Definitions for the journal tag flags word: */
 172 #define JFS_FLAG_ESCAPE         1       /* on-disk block is escaped */
 173 #define JFS_FLAG_SAME_UUID      2       /* block has same uuid as previous */
 174 #define JFS_FLAG_DELETED        4       /* block deleted by this transaction */
 175 #define JFS_FLAG_LAST_TAG       8       /* last tag in this descriptor block */
 176
 177
 178 /*
 179  * The journal superblock.  All fields are in big-endian byte order.
 180  */
 181 typedef struct journal_superblock_s
 182 {
 183 /* 0x0000 */
 184         journal_header_t s_header;
 185
 186 /* 0x000C */
 187         /* Static information describing the journal */
 188         __be32  s_blocksize;            /* journal device blocksize */
 189         __be32  s_maxlen;               /* total blocks in journal file */
 190         __be32  s_first;                /* first block of log information */
 191
 192 /* 0x0018 */
 193         /* Dynamic information describing the current state of the log */
 194         __be32  s_sequence;             /* first commit ID expected in log */
 195         __be32  s_start;                /* blocknr of start of log */
 196
 197 /* 0x0020 */
 198         /* Error value, as set by journal_abort(). */
 199         __be32  s_errno;
 200
 201 /* 0x0024 */
 202         /* Remaining fields are only valid in a version-2 superblock */
 203         __be32  s_feature_compat;       /* compatible feature set */
 204         __be32  s_feature_incompat;     /* incompatible feature set */
 205         __be32  s_feature_ro_compat;    /* readonly-compatible feature set */
 206 /* 0x0030 */
 207         __u8    s_uuid[16];             /* 128-bit uuid for journal */
 208
 209 /* 0x0040 */
 210         __be32  s_nr_users;             /* Nr of filesystems sharing log */
 211
 212         __be32  s_dynsuper;             /* Blocknr of dynamic superblock copy*/
 213
 214 /* 0x0048 */
 215         __be32  s_max_transaction;      /* Limit of journal blocks per trans.*/
 216         __be32  s_max_trans_data;       /* Limit of data blocks per trans. */
 217
 218 /* 0x0050 */
 219         __u32   s_padding[44];
 220
 221 /* 0x0100 */
 222         __u8    s_users[16*48];         /* ids of all fs'es sharing the log */
 223 /* 0x0400 */
 224 } journal_superblock_t;
 225
 226 #define JFS_HAS_COMPAT_FEATURE(j,mask)                                  \
 227         ((j)->j_format_version >= 2 &&                                  \
 228          ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
 229 #define JFS_HAS_RO_COMPAT_FEATURE(j,mask)                               \
 230         ((j)->j_format_version >= 2 &&                                  \
 231          ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
 232 #define JFS_HAS_INCOMPAT_FEATURE(j,mask)                                \
 233         ((j)->j_format_version >= 2 &&                                  \
 234          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
 235
 236 #define JFS_FEATURE_INCOMPAT_REVOKE     0x00000001
 237
 238 /* Features known to this kernel version: */
 239 #define JFS_KNOWN_COMPAT_FEATURES       0
 240 #define JFS_KNOWN_ROCOMPAT_FEATURES     0
 241 #define JFS_KNOWN_INCOMPAT_FEATURES     JFS_FEATURE_INCOMPAT_REVOKE
 242
 243 #ifdef __KERNEL__
 244
 245 #include <linux/fs.h>
 246 #include <linux/sched.h>
 247 #include <linux/jbd_common.h>
 248
 249 #define J_ASSERT(assert)        BUG_ON(!(assert))
 250
 251 #define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
 252 #define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
 253
 254 #if defined(JBD_PARANOID_IOFAIL)
 255 #define J_EXPECT(expr, why...)          J_ASSERT(expr)
 256 #define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
 257 #define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
 258 #else
 259 #define __journal_expect(expr, why...)                                       \
 260         ({                                                                   \
 261                 int val = (expr);                                            \
 262                 if (!val) {                                                  \
 263                         printk(KERN_ERR                                      \
 264                                 "EXT3-fs unexpected failure: %s;\n",# expr); \
 265                         printk(KERN_ERR why "\n");                           \
 266                 }                                                            \
 267                 val;                                                         \
 268         })
 269 #define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)
 270 #define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)
 271 #define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)
 272 #endif
 273
 274 struct jbd_revoke_table_s;
 275
 276 /**
 277  * struct handle_s - this is the concrete type associated with handle_t.
 278  * @h_transaction: Which compound transaction is this update a part of?
 279  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
 280  * @h_ref: Reference count on this handle
 281  * @h_err: Field for caller's use to track errors through large fs operations
 282  * @h_sync: flag for sync-on-close
 283  * @h_jdata: flag to force data journaling
 284  * @h_aborted: flag indicating fatal error on handle
 285  * @h_lockdep_map: lockdep info for debugging lock problems
 286  */
 287 struct handle_s
 288 {
 289         /* Which compound transaction is this update a part of? */
 290         transaction_t           *h_transaction;
 291
 292         /* Number of remaining buffers we are allowed to dirty: */
 293         int                     h_buffer_credits;
 294
 295         /* Reference count on this handle */
 296         int                     h_ref;
 297
 298         /* Field for caller's use to track errors through large fs */
 299         /* operations */
 300         int                     h_err;
 301
 302         /* Flags [no locking] */
 303         unsigned int    h_sync:         1;      /* sync-on-close */
 304         unsigned int    h_jdata:        1;      /* force data journaling */
 305         unsigned int    h_aborted:      1;      /* fatal error on handle */
 306
 307 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 308         struct lockdep_map      h_lockdep_map;
 309 #endif
 310 };
 311
 312
 313 /* The transaction_t type is the guts of the journaling mechanism.  It
 314  * tracks a compound transaction through its various states:
 315  *
 316  * RUNNING:     accepting new updates
 317  * LOCKED:      Updates still running but we don't accept new ones
 318  * RUNDOWN:     Updates are tidying up but have finished requesting
 319  *              new buffers to modify (state not used for now)
 320  * FLUSH:       All updates complete, but we are still writing to disk
 321  * COMMIT:      All data on disk, writing commit record
 322  * FINISHED:    We still have to keep the transaction for checkpointing.
 323  *
 324  * The transaction keeps track of all of the buffers modified by a
 325  * running transaction, and all of the buffers committed but not yet
 326  * flushed to home for finished transactions.
 327  */
 328
 329 /*
 330  * Lock ranking:
 331  *
 332  *    j_list_lock
 333  *      ->jbd_lock_bh_journal_head()    (This is "innermost")
 334  *
 335  *    j_state_lock
 336  *    ->jbd_lock_bh_state()
 337  *
 338  *    jbd_lock_bh_state()
 339  *    ->j_list_lock
 340  *
 341  *    j_state_lock
 342  *    ->t_handle_lock
 343  *
 344  *    j_state_lock
 345  *    ->j_list_lock                     (journal_unmap_buffer)
 346  *
 347  */
 348
 349 struct transaction_s
 350 {
 351         /* Pointer to the journal for this transaction. [no locking] */
 352         journal_t               *t_journal;
 353
 354         /* Sequence number for this transaction [no locking] */
 355         tid_t                   t_tid;
 356
 357         /*
 358          * Transaction's current state
 359          * [no locking - only kjournald alters this]
 360          * [j_list_lock] guards transition of a transaction into T_FINISHED
 361          * state and subsequent call of __journal_drop_transaction()
 362          * FIXME: needs barriers
 363          * KLUDGE: [use j_state_lock]
 364          */
 365         enum {
 366                 T_RUNNING,
 367                 T_LOCKED,
 368                 T_FLUSH,
 369                 T_COMMIT,
 370                 T_COMMIT_RECORD,
 371                 T_FINISHED
 372         }                       t_state;
 373
 374         /*
 375          * Where in the log does this transaction's commit start? [no locking]
 376          */
 377         unsigned int            t_log_start;
 378
 379         /* Number of buffers on the t_buffers list [j_list_lock] */
 380         int                     t_nr_buffers;
 381
 382         /*
 383          * Doubly-linked circular list of all buffers reserved but not yet
 384          * modified by this transaction [j_list_lock]
 385          */
 386         struct journal_head     *t_reserved_list;
 387
 388         /*
 389          * Doubly-linked circular list of all buffers under writeout during
 390          * commit [j_list_lock]
 391          */
 392         struct journal_head     *t_locked_list;
 393
 394         /*
 395          * Doubly-linked circular list of all metadata buffers owned by this
 396          * transaction [j_list_lock]
 397          */
 398         struct journal_head     *t_buffers;
 399
 400         /*
 401          * Doubly-linked circular list of all data buffers still to be
 402          * flushed before this transaction can be committed [j_list_lock]
 403          */
 404         struct journal_head     *t_sync_datalist;
 405
 406         /*
 407          * Doubly-linked circular list of all forget buffers (superseded
 408          * buffers which we can un-checkpoint once this transaction commits)
 409          * [j_list_lock]
 410          */
 411         struct journal_head     *t_forget;
 412
 413         /*
 414          * Doubly-linked circular list of all buffers still to be flushed before
 415          * this transaction can be checkpointed. [j_list_lock]
 416          */
 417         struct journal_head     *t_checkpoint_list;
 418
 419         /*
 420          * Doubly-linked circular list of all buffers submitted for IO while
 421          * checkpointing. [j_list_lock]
 422          */
 423         struct journal_head     *t_checkpoint_io_list;
 424
 425         /*
 426          * Doubly-linked circular list of temporary buffers currently undergoing
 427          * IO in the log [j_list_lock]
 428          */
 429         struct journal_head     *t_iobuf_list;
 430
 431         /*
 432          * Doubly-linked circular list of metadata buffers being shadowed by log
 433          * IO.  The IO buffers on the iobuf list and the shadow buffers on this
 434          * list match each other one for one at all times. [j_list_lock]
 435          */
 436         struct journal_head     *t_shadow_list;
 437
 438         /*
 439          * Doubly-linked circular list of control buffers being written to the
 440          * log. [j_list_lock]
 441          */
 442         struct journal_head     *t_log_list;
 443
 444         /*
 445          * Protects info related to handles
 446          */
 447         spinlock_t              t_handle_lock;
 448
 449         /*
 450          * Number of outstanding updates running on this transaction
 451          * [t_handle_lock]
 452          */
 453         int                     t_updates;
 454
 455         /*
 456          * Number of buffers reserved for use by all handles in this transaction
 457          * handle but not yet modified. [t_handle_lock]
 458          */
 459         int                     t_outstanding_credits;
 460
 461         /*
 462          * Forward and backward links for the circular list of all transactions
 463          * awaiting checkpoint. [j_list_lock]
 464          */
 465         transaction_t           *t_cpnext, *t_cpprev;
 466
 467         /*
 468          * When will the transaction expire (become due for commit), in jiffies?
 469          * [no locking]
 470          */
 471         unsigned long           t_expires;
 472
 473         /*
 474          * When this transaction started, in nanoseconds [no locking]
 475          */
 476         ktime_t                 t_start_time;
 477
 478         /*
 479          * How many handles used this transaction? [t_handle_lock]
 480          */
 481         int t_handle_count;
 482
 483         /*
 484          * This transaction is being forced and some process is
 485          * waiting for it to finish.
 486          */
 487         unsigned int t_synchronous_commit:1;
 488 };
 489
 490 /**
 491  * struct journal_s - this is the concrete type associated with journal_t.
 492  * @j_flags:  General journaling state flags
 493  * @j_errno:  Is there an outstanding uncleared error on the journal (from a
 494  *     prior abort)?
 495  * @j_sb_buffer: First part of superblock buffer
 496  * @j_superblock: Second part of superblock buffer
 497  * @j_format_version: Version of the superblock format
 498  * @j_state_lock: Protect the various scalars in the journal
 499  * @j_barrier_count:  Number of processes waiting to create a barrier lock
 500  * @j_barrier: The barrier lock itself
 501  * @j_running_transaction: The current running transaction..
 502  * @j_committing_transaction: the transaction we are pushing to disk
 503  * @j_checkpoint_transactions: a linked circular list of all transactions
 504  *  waiting for checkpointing
 505  * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
 506  *  to start committing, or for a barrier lock to be released
 507  * @j_wait_logspace: Wait queue for waiting for checkpointing to complete
 508  * @j_wait_done_commit: Wait queue for waiting for commit to complete
 509  * @j_wait_checkpoint:  Wait queue to trigger checkpointing
 510  * @j_wait_commit: Wait queue to trigger commit
 511  * @j_wait_updates: Wait queue to wait for updates to complete
 512  * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
 513  * @j_head: Journal head - identifies the first unused block in the journal
 514  * @j_tail: Journal tail - identifies the oldest still-used block in the
 515  *  journal.
 516  * @j_free: Journal free - how many free blocks are there in the journal?
 517  * @j_first: The block number of the first usable block
 518  * @j_last: The block number one beyond the last usable block
 519  * @j_dev: Device where we store the journal
 520  * @j_blocksize: blocksize for the location where we store the journal.
 521  * @j_blk_offset: starting block offset for into the device where we store the
 522  *     journal
 523  * @j_fs_dev: Device which holds the client fs.  For internal journal this will
 524  *     be equal to j_dev
 525  * @j_maxlen: Total maximum capacity of the journal region on disk.
 526  * @j_list_lock: Protects the buffer lists and internal buffer state.
 527  * @j_inode: Optional inode where we store the journal.  If present, all journal
 528  *     block numbers are mapped into this inode via bmap().
 529  * @j_tail_sequence:  Sequence number of the oldest transaction in the log
 530  * @j_transaction_sequence: Sequence number of the next transaction to grant
 531  * @j_commit_sequence: Sequence number of the most recently committed
 532  *  transaction
 533  * @j_commit_request: Sequence number of the most recent transaction wanting
 534  *     commit
 535  * @j_uuid: Uuid of client object.
 536  * @j_task: Pointer to the current commit thread for this journal
 537  * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
 538  *     single compound commit transaction
 539  * @j_commit_interval: What is the maximum transaction lifetime before we begin
 540  *  a commit?
 541  * @j_commit_timer:  The timer used to wakeup the commit thread
 542  * @j_revoke_lock: Protect the revoke table
 543  * @j_revoke: The revoke table - maintains the list of revoked blocks in the
 544  *     current transaction.
 545  * @j_revoke_table: alternate revoke tables for j_revoke
 546  * @j_wbuf: array of buffer_heads for journal_commit_transaction
 547  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
 548  *      number that will fit in j_blocksize
 549  * @j_last_sync_writer: most recent pid which did a synchronous write
 550  * @j_average_commit_time: the average amount of time in nanoseconds it
 551  *      takes to commit a transaction to the disk.
 552  * @j_private: An opaque pointer to fs-private information.
 553  */
 554
 555 struct journal_s
 556 {
 557         /* General journaling state flags [j_state_lock] */
 558         unsigned long           j_flags;
 559
 560         /*
 561          * Is there an outstanding uncleared error on the journal (from a prior
 562          * abort)? [j_state_lock]
 563          */
 564         int                     j_errno;
 565
 566         /* The superblock buffer */
 567         struct buffer_head      *j_sb_buffer;
 568         journal_superblock_t    *j_superblock;
 569
 570         /* Version of the superblock format */
 571         int                     j_format_version;
 572
 573         /*
 574          * Protect the various scalars in the journal
 575          */
 576         spinlock_t              j_state_lock;
 577
 578         /*
 579          * Number of processes waiting to create a barrier lock [j_state_lock]
 580          */
 581         int                     j_barrier_count;
 582
 583         /* The barrier lock itself */
 584         struct mutex            j_barrier;
 585
 586         /*
 587          * Transactions: The current running transaction...
 588          * [j_state_lock] [caller holding open handle]
 589          */
 590         transaction_t           *j_running_transaction;
 591
 592         /*
 593          * the transaction we are pushing to disk
 594          * [j_state_lock] [caller holding open handle]
 595          */
 596         transaction_t           *j_committing_transaction;
 597
 598         /*
 599          * ... and a linked circular list of all transactions waiting for
 600          * checkpointing. [j_list_lock]
 601          */
 602         transaction_t           *j_checkpoint_transactions;
 603
 604         /*
 605          * Wait queue for waiting for a locked transaction to start committing,
 606          * or for a barrier lock to be released
 607          */
 608         wait_queue_head_t       j_wait_transaction_locked;
 609
 610         /* Wait queue for waiting for checkpointing to complete */
 611         wait_queue_head_t       j_wait_logspace;
 612
 613         /* Wait queue for waiting for commit to complete */
 614         wait_queue_head_t       j_wait_done_commit;
 615
 616         /* Wait queue to trigger checkpointing */
 617         wait_queue_head_t       j_wait_checkpoint;
 618
 619         /* Wait queue to trigger commit */
 620         wait_queue_head_t       j_wait_commit;
 621
 622         /* Wait queue to wait for updates to complete */
 623         wait_queue_head_t       j_wait_updates;
 624
 625         /* Semaphore for locking against concurrent checkpoints */
 626         struct mutex            j_checkpoint_mutex;
 627
 628         /*
 629          * Journal head: identifies the first unused block in the journal.
 630          * [j_state_lock]
 631          */
 632         unsigned int            j_head;
 633
 634         /*
 635          * Journal tail: identifies the oldest still-used block in the journal.
 636          * [j_state_lock]
 637          */
 638         unsigned int            j_tail;
 639
 640         /*
 641          * Journal free: how many free blocks are there in the journal?
 642          * [j_state_lock]
 643          */
 644         unsigned int            j_free;
 645
 646         /*
 647          * Journal start and end: the block numbers of the first usable block
 648          * and one beyond the last usable block in the journal. [j_state_lock]
 649          */
 650         unsigned int            j_first;
 651         unsigned int            j_last;
 652
 653         /*
 654          * Device, blocksize and starting block offset for the location where we
 655          * store the journal.
 656          */
 657         struct block_device     *j_dev;
 658         int                     j_blocksize;
 659         unsigned int            j_blk_offset;
 660
 661         /*
 662          * Device which holds the client fs.  For internal journal this will be
 663          * equal to j_dev.
 664          */
 665         struct block_device     *j_fs_dev;
 666
 667         /* Total maximum capacity of the journal region on disk. */
 668         unsigned int            j_maxlen;
 669
 670         /*
 671          * Protects the buffer lists and internal buffer state.
 672          */
 673         spinlock_t              j_list_lock;
 674
 675         /* Optional inode where we store the journal.  If present, all */
 676         /* journal block numbers are mapped into this inode via */
 677         /* bmap(). */
 678         struct inode            *j_inode;
 679
 680         /*
 681          * Sequence number of the oldest transaction in the log [j_state_lock]
 682          */
 683         tid_t                   j_tail_sequence;
 684
 685         /*
 686          * Sequence number of the next transaction to grant [j_state_lock]
 687          */
 688         tid_t                   j_transaction_sequence;
 689
 690         /*
 691          * Sequence number of the most recently committed transaction
 692          * [j_state_lock].
 693          */
 694         tid_t                   j_commit_sequence;
 695
 696         /*
 697          * Sequence number of the most recent transaction wanting commit
 698          * [j_state_lock]
 699          */
 700         tid_t                   j_commit_request;
 701
 702         /*
 703          * Journal uuid: identifies the object (filesystem, LVM volume etc)
 704          * backed by this journal.  This will eventually be replaced by an array
 705          * of uuids, allowing us to index multiple devices within a single
 706          * journal and to perform atomic updates across them.
 707          */
 708         __u8                    j_uuid[16];
 709
 710         /* Pointer to the current commit thread for this journal */
 711         struct task_struct      *j_task;
 712
 713         /*
 714          * Maximum number of metadata buffers to allow in a single compound
 715          * commit transaction
 716          */
 717         int                     j_max_transaction_buffers;
 718
 719         /*
 720          * What is the maximum transaction lifetime before we begin a commit?
 721          */
 722         unsigned long           j_commit_interval;
 723
 724         /* The timer used to wakeup the commit thread: */
 725         struct timer_list       j_commit_timer;
 726
 727         /*
 728          * The revoke table: maintains the list of revoked blocks in the
 729          * current transaction.  [j_revoke_lock]
 730          */
 731         spinlock_t              j_revoke_lock;
 732         struct jbd_revoke_table_s *j_revoke;
 733         struct jbd_revoke_table_s *j_revoke_table[2];
 734
 735         /*
 736          * array of bhs for journal_commit_transaction
 737          */
 738         struct buffer_head      **j_wbuf;
 739         int                     j_wbufsize;
 740
 741         /*
 742          * this is the pid of the last person to run a synchronous operation
 743          * through the journal.
 744          */
 745         pid_t                   j_last_sync_writer;
 746
 747         /*
 748          * the average amount of time in nanoseconds it takes to commit a
 749          * transaction to the disk.  [j_state_lock]
 750          */
 751         u64                     j_average_commit_time;
 752
 753         /*
 754          * An opaque pointer to fs-private information.  ext3 puts its
 755          * superblock pointer here
 756          */
 757         void *j_private;
 758 };
 759
 760 /*
 761  * Journal flag definitions
 762  */
 763 #define JFS_UNMOUNT     0x001   /* Journal thread is being destroyed */
 764 #define JFS_ABORT       0x002   /* Journaling has been aborted for errors. */
 765 #define JFS_ACK_ERR     0x004   /* The errno in the sb has been acked */
 766 #define JFS_FLUSHED     0x008   /* The journal superblock has been flushed */
 767 #define JFS_LOADED      0x010   /* The journal superblock has been loaded */
 768 #define JFS_BARRIER     0x020   /* Use IDE barriers */
 769 #define JFS_ABORT_ON_SYNCDATA_ERR       0x040  /* Abort the journal on file
 770                                                 * data write error in ordered
 771                                                 * mode */
 772
 773 /*
 774  * Function declarations for the journaling transaction and buffer
 775  * management
 776  */
 777
 778 /* Filing buffers */
 779 extern void journal_unfile_buffer(journal_t *, struct journal_head *);
 780 extern void __journal_unfile_buffer(struct journal_head *);
 781 extern void __journal_refile_buffer(struct journal_head *);
 782 extern void journal_refile_buffer(journal_t *, struct journal_head *);
 783 extern void __journal_file_buffer(struct journal_head *, transaction_t *, int);
 784 extern void __journal_free_buffer(struct journal_head *bh);
 785 extern void journal_file_buffer(struct journal_head *, transaction_t *, int);
 786 extern void __journal_clean_data_list(transaction_t *transaction);
 787
 788 /* Log buffer allocation */
 789 extern struct journal_head * journal_get_descriptor_buffer(journal_t *);
 790 int journal_next_log_block(journal_t *, unsigned int *);
 791
 792 /* Commit management */
 793 extern void journal_commit_transaction(journal_t *);
 794
 795 /* Checkpoint list management */
 796 int __journal_clean_checkpoint_list(journal_t *journal);
 797 int __journal_remove_checkpoint(struct journal_head *);
 798 void __journal_insert_checkpoint(struct journal_head *, transaction_t *);
 799
 800 /* Buffer IO */
 801 extern int
 802 journal_write_metadata_buffer(transaction_t       *transaction,
 803                               struct journal_head  *jh_in,
 804                               struct journal_head **jh_out,
 805                               unsigned int blocknr);
 806
 807 /* Transaction locking */
 808 extern void             __wait_on_journal (journal_t *);
 809
 810 /*
 811  * Journal locking.
 812  *
 813  * We need to lock the journal during transaction state changes so that nobody
 814  * ever tries to take a handle on the running transaction while we are in the
 815  * middle of moving it to the commit phase.  j_state_lock does this.
 816  *
 817  * Note that the locking is completely interrupt unsafe.  We never touch
 818  * journal structures from interrupts.
 819  */
 820
 821 static inline handle_t *journal_current_handle(void)
 822 {
 823         return current->journal_info;
 824 }
 825
 826 /* The journaling code user interface:
 827  *
 828  * Create and destroy handles
 829  * Register buffer modifications against the current transaction.
 830  */
 831
 832 extern handle_t *journal_start(journal_t *, int nblocks);
 833 extern int       journal_restart (handle_t *, int nblocks);
 834 extern int       journal_extend (handle_t *, int nblocks);
 835 extern int       journal_get_write_access(handle_t *, struct buffer_head *);
 836 extern int       journal_get_create_access (handle_t *, struct buffer_head *);
 837 extern int       journal_get_undo_access(handle_t *, struct buffer_head *);
 838 extern int       journal_dirty_data (handle_t *, struct buffer_head *);
 839 extern int       journal_dirty_metadata (handle_t *, struct buffer_head *);
 840 extern void      journal_release_buffer (handle_t *, struct buffer_head *);
 841 extern int       journal_forget (handle_t *, struct buffer_head *);
 842 extern void      journal_sync_buffer (struct buffer_head *);
 843 extern void      journal_invalidatepage(journal_t *,
 844                                 struct page *, unsigned long);
 845 extern int       journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
 846 extern int       journal_stop(handle_t *);
 847 extern int       journal_flush (journal_t *);
 848 extern void      journal_lock_updates (journal_t *);
 849 extern void      journal_unlock_updates (journal_t *);
 850
 851 extern journal_t * journal_init_dev(struct block_device *bdev,
 852                                 struct block_device *fs_dev,
 853                                 int start, int len, int bsize);
 854 extern journal_t * journal_init_inode (struct inode *);
 855 extern int         journal_update_format (journal_t *);
 856 extern int         journal_check_used_features
 857                    (journal_t *, unsigned long, unsigned long, unsigned long);
 858 extern int         journal_check_available_features
 859                    (journal_t *, unsigned long, unsigned long, unsigned long);
 860 extern int         journal_set_features
 861                    (journal_t *, unsigned long, unsigned long, unsigned long);
 862 extern int         journal_create     (journal_t *);
 863 extern int         journal_load       (journal_t *journal);
 864 extern int         journal_destroy    (journal_t *);
 865 extern int         journal_recover    (journal_t *journal);
 866 extern int         journal_wipe       (journal_t *, int);
 867 extern int         journal_skip_recovery        (journal_t *);
 868 extern void        journal_update_superblock    (journal_t *, int);
 869 extern void        journal_abort      (journal_t *, int);
 870 extern int         journal_errno      (journal_t *);
 871 extern void        journal_ack_err    (journal_t *);
 872 extern int         journal_clear_err  (journal_t *);
 873 extern int         journal_bmap(journal_t *, unsigned int, unsigned int *);
 874 extern int         journal_force_commit(journal_t *);
 875
 876 /*
 877  * journal_head management
 878  */
 879 struct journal_head *journal_add_journal_head(struct buffer_head *bh);
 880 struct journal_head *journal_grab_journal_head(struct buffer_head *bh);
 881 void journal_put_journal_head(struct journal_head *jh);
 882
 883 /*
 884  * handle management
 885  */
 886 extern struct kmem_cache *jbd_handle_cache;
 887
 888 static inline handle_t *jbd_alloc_handle(gfp_t gfp_flags)
 889 {
 890         return kmem_cache_alloc(jbd_handle_cache, gfp_flags);
 891 }
 892
 893 static inline void jbd_free_handle(handle_t *handle)
 894 {
 895         kmem_cache_free(jbd_handle_cache, handle);
 896 }
 897
 898 /* Primary revoke support */
 899 #define JOURNAL_REVOKE_DEFAULT_HASH 256
 900 extern int         journal_init_revoke(journal_t *, int);
 901 extern void        journal_destroy_revoke_caches(void);
 902 extern int         journal_init_revoke_caches(void);
 903
 904 extern void        journal_destroy_revoke(journal_t *);
 905 extern int         journal_revoke (handle_t *,
 906                                 unsigned int, struct buffer_head *);
 907 extern int         journal_cancel_revoke(handle_t *, struct journal_head *);
 908 extern void        journal_write_revoke_records(journal_t *,
 909                                                 transaction_t *, int);
 910
 911 /* Recovery revoke support */
 912 extern int      journal_set_revoke(journal_t *, unsigned int, tid_t);
 913 extern int      journal_test_revoke(journal_t *, unsigned int, tid_t);
 914 extern void     journal_clear_revoke(journal_t *);
 915 extern void     journal_switch_revoke_table(journal_t *journal);
 916
 917 /*
 918  * The log thread user interface:
 919  *
 920  * Request space in the current transaction, and force transaction commit
 921  * transitions on demand.
 922  */
 923
 924 int __log_space_left(journal_t *); /* Called with journal locked */
 925 int log_start_commit(journal_t *journal, tid_t tid);
 926 int __log_start_commit(journal_t *journal, tid_t tid);
 927 int journal_start_commit(journal_t *journal, tid_t *tid);
 928 int journal_force_commit_nested(journal_t *journal);
 929 int log_wait_commit(journal_t *journal, tid_t tid);
 930 int log_do_checkpoint(journal_t *journal);
 931 int journal_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
 932
 933 void __log_wait_for_space(journal_t *journal);
 934 extern void     __journal_drop_transaction(journal_t *, transaction_t *);
 935 extern int      cleanup_journal_tail(journal_t *);
 936
 937 /* Debugging code only: */
 938
 939 #define jbd_ENOSYS() \
 940 do {                                                                       \
 941         printk (KERN_ERR "JBD unimplemented function %s\n", __func__); \
 942         current->state = TASK_UNINTERRUPTIBLE;                             \
 943         schedule();                                                        \
 944 } while (1)
 945
 946 /*
 947  * is_journal_abort
 948  *
 949  * Simple test wrapper function to test the JFS_ABORT state flag.  This
 950  * bit, when set, indicates that we have had a fatal error somewhere,
 951  * either inside the journaling layer or indicated to us by the client
 952  * (eg. ext3), and that we and should not commit any further
 953  * transactions.
 954  */
 955
 956 static inline int is_journal_aborted(journal_t *journal)
 957 {
 958         return journal->j_flags & JFS_ABORT;
 959 }
 960
 961 static inline int is_handle_aborted(handle_t *handle)
 962 {
 963         if (handle->h_aborted)
 964                 return 1;
 965         return is_journal_aborted(handle->h_transaction->t_journal);
 966 }
 967
 968 static inline void journal_abort_handle(handle_t *handle)
 969 {
 970         handle->h_aborted = 1;
 971 }
 972
 973 #endif /* __KERNEL__   */
 974
 975 /* Comparison functions for transaction IDs: perform comparisons using
 976  * modulo arithmetic so that they work over sequence number wraps. */
 977
 978 static inline int tid_gt(tid_t x, tid_t y)
 979 {
 980         int difference = (x - y);
 981         return (difference > 0);
 982 }
 983
 984 static inline int tid_geq(tid_t x, tid_t y)
 985 {
 986         int difference = (x - y);
 987         return (difference >= 0);
 988 }
 989
 990 extern int journal_blocks_per_page(struct inode *inode);
 991
 992 /*
 993  * Return the minimum number of blocks which must be free in the journal
 994  * before a new transaction may be started.  Must be called under j_state_lock.
 995  */
 996 static inline int jbd_space_needed(journal_t *journal)
 997 {
 998         int nblocks = journal->j_max_transaction_buffers;
 999         if (journal->j_committing_transaction)
1000                 nblocks += journal->j_committing_transaction->
1001                                         t_outstanding_credits;
1002         return nblocks;
1003 }
1004
1005 /*
1006  * Definitions which augment the buffer_head layer
1007  */
1008
1009 /* journaling buffer types */
1010 #define BJ_None         0       /* Not journaled */
1011 #define BJ_SyncData     1       /* Normal data: flush before commit */
1012 #define BJ_Metadata     2       /* Normal journaled metadata */
1013 #define BJ_Forget       3       /* Buffer superseded by this transaction */
1014 #define BJ_IO           4       /* Buffer is for temporary IO use */
1015 #define BJ_Shadow       5       /* Buffer contents being shadowed to the log */
1016 #define BJ_LogCtl       6       /* Buffer contains log descriptors */
1017 #define BJ_Reserved     7       /* Buffer is reserved for access by journal */
1018 #define BJ_Locked       8       /* Locked for I/O during commit */
1019 #define BJ_Types        9
1020
1021 extern int jbd_blocks_per_page(struct inode *inode);
1022
1023 #ifdef __KERNEL__
1024
1025 #define buffer_trace_init(bh)   do {} while (0)
1026 #define print_buffer_fields(bh) do {} while (0)
1027 #define print_buffer_trace(bh)  do {} while (0)
1028 #define BUFFER_TRACE(bh, info)  do {} while (0)
1029 #define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1030 #define JBUFFER_TRACE(jh, info) do {} while (0)
1031
1032 #endif  /* __KERNEL__ */
1033
1034 #endif  /* _LINUX_JBD_H */