linux/include/linux/jbd.h
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   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
  59extern 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
  73static inline void *jbd_alloc(size_t size, gfp_t flags)
  74{
  75        return (void *)__get_free_pages(flags, get_order(size));
  76}
  77
  78static 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 **/
 103typedef 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 **/
 117typedef 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 */
 143typedef 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 */
 154typedef 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 */
 164typedef 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 */
 181typedef 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
 274struct 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 */
 287struct 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
 349struct 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/**
 485 * struct journal_s - this is the concrete type associated with journal_t.
 486 * @j_flags:  General journaling state flags
 487 * @j_errno:  Is there an outstanding uncleared error on the journal (from a
 488 *     prior abort)?
 489 * @j_sb_buffer: First part of superblock buffer
 490 * @j_superblock: Second part of superblock buffer
 491 * @j_format_version: Version of the superblock format
 492 * @j_state_lock: Protect the various scalars in the journal
 493 * @j_barrier_count:  Number of processes waiting to create a barrier lock
 494 * @j_running_transaction: The current running transaction..
 495 * @j_committing_transaction: the transaction we are pushing to disk
 496 * @j_checkpoint_transactions: a linked circular list of all transactions
 497 *  waiting for checkpointing
 498 * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
 499 *  to start committing, or for a barrier lock to be released
 500 * @j_wait_logspace: Wait queue for waiting for checkpointing to complete
 501 * @j_wait_done_commit: Wait queue for waiting for commit to complete
 502 * @j_wait_checkpoint:  Wait queue to trigger checkpointing
 503 * @j_wait_commit: Wait queue to trigger commit
 504 * @j_wait_updates: Wait queue to wait for updates to complete
 505 * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
 506 * @j_head: Journal head - identifies the first unused block in the journal
 507 * @j_tail: Journal tail - identifies the oldest still-used block in the
 508 *  journal.
 509 * @j_free: Journal free - how many free blocks are there in the journal?
 510 * @j_first: The block number of the first usable block
 511 * @j_last: The block number one beyond the last usable block
 512 * @j_dev: Device where we store the journal
 513 * @j_blocksize: blocksize for the location where we store the journal.
 514 * @j_blk_offset: starting block offset for into the device where we store the
 515 *     journal
 516 * @j_fs_dev: Device which holds the client fs.  For internal journal this will
 517 *     be equal to j_dev
 518 * @j_maxlen: Total maximum capacity of the journal region on disk.
 519 * @j_list_lock: Protects the buffer lists and internal buffer state.
 520 * @j_inode: Optional inode where we store the journal.  If present, all journal
 521 *     block numbers are mapped into this inode via bmap().
 522 * @j_tail_sequence:  Sequence number of the oldest transaction in the log
 523 * @j_transaction_sequence: Sequence number of the next transaction to grant
 524 * @j_commit_sequence: Sequence number of the most recently committed
 525 *  transaction
 526 * @j_commit_request: Sequence number of the most recent transaction wanting
 527 *     commit
 528 * @j_commit_waited: Sequence number of the most recent transaction someone
 529 *     is waiting for to commit.
 530 * @j_uuid: Uuid of client object.
 531 * @j_task: Pointer to the current commit thread for this journal
 532 * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
 533 *     single compound commit transaction
 534 * @j_commit_interval: What is the maximum transaction lifetime before we begin
 535 *  a commit?
 536 * @j_commit_timer:  The timer used to wakeup the commit thread
 537 * @j_revoke_lock: Protect the revoke table
 538 * @j_revoke: The revoke table - maintains the list of revoked blocks in the
 539 *     current transaction.
 540 * @j_revoke_table: alternate revoke tables for j_revoke
 541 * @j_wbuf: array of buffer_heads for journal_commit_transaction
 542 * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
 543 *      number that will fit in j_blocksize
 544 * @j_last_sync_writer: most recent pid which did a synchronous write
 545 * @j_average_commit_time: the average amount of time in nanoseconds it
 546 *      takes to commit a transaction to the disk.
 547 * @j_private: An opaque pointer to fs-private information.
 548 */
 549
 550struct journal_s
 551{
 552        /* General journaling state flags [j_state_lock] */
 553        unsigned long           j_flags;
 554
 555        /*
 556         * Is there an outstanding uncleared error on the journal (from a prior
 557         * abort)? [j_state_lock]
 558         */
 559        int                     j_errno;
 560
 561        /* The superblock buffer */
 562        struct buffer_head      *j_sb_buffer;
 563        journal_superblock_t    *j_superblock;
 564
 565        /* Version of the superblock format */
 566        int                     j_format_version;
 567
 568        /*
 569         * Protect the various scalars in the journal
 570         */
 571        spinlock_t              j_state_lock;
 572
 573        /*
 574         * Number of processes waiting to create a barrier lock [j_state_lock]
 575         */
 576        int                     j_barrier_count;
 577
 578        /*
 579         * Transactions: The current running transaction...
 580         * [j_state_lock] [caller holding open handle]
 581         */
 582        transaction_t           *j_running_transaction;
 583
 584        /*
 585         * the transaction we are pushing to disk
 586         * [j_state_lock] [caller holding open handle]
 587         */
 588        transaction_t           *j_committing_transaction;
 589
 590        /*
 591         * ... and a linked circular list of all transactions waiting for
 592         * checkpointing. [j_list_lock]
 593         */
 594        transaction_t           *j_checkpoint_transactions;
 595
 596        /*
 597         * Wait queue for waiting for a locked transaction to start committing,
 598         * or for a barrier lock to be released
 599         */
 600        wait_queue_head_t       j_wait_transaction_locked;
 601
 602        /* Wait queue for waiting for checkpointing to complete */
 603        wait_queue_head_t       j_wait_logspace;
 604
 605        /* Wait queue for waiting for commit to complete */
 606        wait_queue_head_t       j_wait_done_commit;
 607
 608        /* Wait queue to trigger checkpointing */
 609        wait_queue_head_t       j_wait_checkpoint;
 610
 611        /* Wait queue to trigger commit */
 612        wait_queue_head_t       j_wait_commit;
 613
 614        /* Wait queue to wait for updates to complete */
 615        wait_queue_head_t       j_wait_updates;
 616
 617        /* Semaphore for locking against concurrent checkpoints */
 618        struct mutex            j_checkpoint_mutex;
 619
 620        /*
 621         * Journal head: identifies the first unused block in the journal.
 622         * [j_state_lock]
 623         */
 624        unsigned int            j_head;
 625
 626        /*
 627         * Journal tail: identifies the oldest still-used block in the journal.
 628         * [j_state_lock]
 629         */
 630        unsigned int            j_tail;
 631
 632        /*
 633         * Journal free: how many free blocks are there in the journal?
 634         * [j_state_lock]
 635         */
 636        unsigned int            j_free;
 637
 638        /*
 639         * Journal start and end: the block numbers of the first usable block
 640         * and one beyond the last usable block in the journal. [j_state_lock]
 641         */
 642        unsigned int            j_first;
 643        unsigned int            j_last;
 644
 645        /*
 646         * Device, blocksize and starting block offset for the location where we
 647         * store the journal.
 648         */
 649        struct block_device     *j_dev;
 650        int                     j_blocksize;
 651        unsigned int            j_blk_offset;
 652
 653        /*
 654         * Device which holds the client fs.  For internal journal this will be
 655         * equal to j_dev.
 656         */
 657        struct block_device     *j_fs_dev;
 658
 659        /* Total maximum capacity of the journal region on disk. */
 660        unsigned int            j_maxlen;
 661
 662        /*
 663         * Protects the buffer lists and internal buffer state.
 664         */
 665        spinlock_t              j_list_lock;
 666
 667        /* Optional inode where we store the journal.  If present, all */
 668        /* journal block numbers are mapped into this inode via */
 669        /* bmap(). */
 670        struct inode            *j_inode;
 671
 672        /*
 673         * Sequence number of the oldest transaction in the log [j_state_lock]
 674         */
 675        tid_t                   j_tail_sequence;
 676
 677        /*
 678         * Sequence number of the next transaction to grant [j_state_lock]
 679         */
 680        tid_t                   j_transaction_sequence;
 681
 682        /*
 683         * Sequence number of the most recently committed transaction
 684         * [j_state_lock].
 685         */
 686        tid_t                   j_commit_sequence;
 687
 688        /*
 689         * Sequence number of the most recent transaction wanting commit
 690         * [j_state_lock]
 691         */
 692        tid_t                   j_commit_request;
 693
 694        /*
 695         * Sequence number of the most recent transaction someone is waiting
 696         * for to commit.
 697         * [j_state_lock]
 698         */
 699        tid_t                   j_commit_waited;
 700
 701        /*
 702         * Journal uuid: identifies the object (filesystem, LVM volume etc)
 703         * backed by this journal.  This will eventually be replaced by an array
 704         * of uuids, allowing us to index multiple devices within a single
 705         * journal and to perform atomic updates across them.
 706         */
 707        __u8                    j_uuid[16];
 708
 709        /* Pointer to the current commit thread for this journal */
 710        struct task_struct      *j_task;
 711
 712        /*
 713         * Maximum number of metadata buffers to allow in a single compound
 714         * commit transaction
 715         */
 716        int                     j_max_transaction_buffers;
 717
 718        /*
 719         * What is the maximum transaction lifetime before we begin a commit?
 720         */
 721        unsigned long           j_commit_interval;
 722
 723        /* The timer used to wakeup the commit thread: */
 724        struct timer_list       j_commit_timer;
 725
 726        /*
 727         * The revoke table: maintains the list of revoked blocks in the
 728         * current transaction.  [j_revoke_lock]
 729         */
 730        spinlock_t              j_revoke_lock;
 731        struct jbd_revoke_table_s *j_revoke;
 732        struct jbd_revoke_table_s *j_revoke_table[2];
 733
 734        /*
 735         * array of bhs for journal_commit_transaction
 736         */
 737        struct buffer_head      **j_wbuf;
 738        int                     j_wbufsize;
 739
 740        /*
 741         * this is the pid of the last person to run a synchronous operation
 742         * through the journal.
 743         */
 744        pid_t                   j_last_sync_writer;
 745
 746        /*
 747         * the average amount of time in nanoseconds it takes to commit a
 748         * transaction to the disk.  [j_state_lock]
 749         */
 750        u64                     j_average_commit_time;
 751
 752        /*
 753         * An opaque pointer to fs-private information.  ext3 puts its
 754         * superblock pointer here
 755         */
 756        void *j_private;
 757};
 758
 759/*
 760 * Journal flag definitions
 761 */
 762#define JFS_UNMOUNT     0x001   /* Journal thread is being destroyed */
 763#define JFS_ABORT       0x002   /* Journaling has been aborted for errors. */
 764#define JFS_ACK_ERR     0x004   /* The errno in the sb has been acked */
 765#define JFS_FLUSHED     0x008   /* The journal superblock has been flushed */
 766#define JFS_LOADED      0x010   /* The journal superblock has been loaded */
 767#define JFS_BARRIER     0x020   /* Use IDE barriers */
 768#define JFS_ABORT_ON_SYNCDATA_ERR       0x040  /* Abort the journal on file
 769                                                * data write error in ordered
 770                                                * mode */
 771
 772/*
 773 * Function declarations for the journaling transaction and buffer
 774 * management
 775 */
 776
 777/* Filing buffers */
 778extern void journal_unfile_buffer(journal_t *, struct journal_head *);
 779extern void __journal_unfile_buffer(struct journal_head *);
 780extern void __journal_refile_buffer(struct journal_head *);
 781extern void journal_refile_buffer(journal_t *, struct journal_head *);
 782extern void __journal_file_buffer(struct journal_head *, transaction_t *, int);
 783extern void __journal_free_buffer(struct journal_head *bh);
 784extern void journal_file_buffer(struct journal_head *, transaction_t *, int);
 785extern void __journal_clean_data_list(transaction_t *transaction);
 786
 787/* Log buffer allocation */
 788extern struct journal_head * journal_get_descriptor_buffer(journal_t *);
 789int journal_next_log_block(journal_t *, unsigned int *);
 790
 791/* Commit management */
 792extern void journal_commit_transaction(journal_t *);
 793
 794/* Checkpoint list management */
 795int __journal_clean_checkpoint_list(journal_t *journal);
 796int __journal_remove_checkpoint(struct journal_head *);
 797void __journal_insert_checkpoint(struct journal_head *, transaction_t *);
 798
 799/* Buffer IO */
 800extern int
 801journal_write_metadata_buffer(transaction_t       *transaction,
 802                              struct journal_head  *jh_in,
 803                              struct journal_head **jh_out,
 804                              unsigned int blocknr);
 805
 806/* Transaction locking */
 807extern void             __wait_on_journal (journal_t *);
 808
 809/*
 810 * Journal locking.
 811 *
 812 * We need to lock the journal during transaction state changes so that nobody
 813 * ever tries to take a handle on the running transaction while we are in the
 814 * middle of moving it to the commit phase.  j_state_lock does this.
 815 *
 816 * Note that the locking is completely interrupt unsafe.  We never touch
 817 * journal structures from interrupts.
 818 */
 819
 820static inline handle_t *journal_current_handle(void)
 821{
 822        return current->journal_info;
 823}
 824
 825/* The journaling code user interface:
 826 *
 827 * Create and destroy handles
 828 * Register buffer modifications against the current transaction.
 829 */
 830
 831extern handle_t *journal_start(journal_t *, int nblocks);
 832extern int       journal_restart (handle_t *, int nblocks);
 833extern int       journal_extend (handle_t *, int nblocks);
 834extern int       journal_get_write_access(handle_t *, struct buffer_head *);
 835extern int       journal_get_create_access (handle_t *, struct buffer_head *);
 836extern int       journal_get_undo_access(handle_t *, struct buffer_head *);
 837extern int       journal_dirty_data (handle_t *, struct buffer_head *);
 838extern int       journal_dirty_metadata (handle_t *, struct buffer_head *);
 839extern void      journal_release_buffer (handle_t *, struct buffer_head *);
 840extern int       journal_forget (handle_t *, struct buffer_head *);
 841extern void      journal_sync_buffer (struct buffer_head *);
 842extern void      journal_invalidatepage(journal_t *,
 843                                struct page *, unsigned long);
 844extern int       journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
 845extern int       journal_stop(handle_t *);
 846extern int       journal_flush (journal_t *);
 847extern void      journal_lock_updates (journal_t *);
 848extern void      journal_unlock_updates (journal_t *);
 849
 850extern journal_t * journal_init_dev(struct block_device *bdev,
 851                                struct block_device *fs_dev,
 852                                int start, int len, int bsize);
 853extern journal_t * journal_init_inode (struct inode *);
 854extern int         journal_update_format (journal_t *);
 855extern int         journal_check_used_features
 856                   (journal_t *, unsigned long, unsigned long, unsigned long);
 857extern int         journal_check_available_features
 858                   (journal_t *, unsigned long, unsigned long, unsigned long);
 859extern int         journal_set_features
 860                   (journal_t *, unsigned long, unsigned long, unsigned long);
 861extern int         journal_create     (journal_t *);
 862extern int         journal_load       (journal_t *journal);
 863extern int         journal_destroy    (journal_t *);
 864extern int         journal_recover    (journal_t *journal);
 865extern int         journal_wipe       (journal_t *, int);
 866extern int         journal_skip_recovery        (journal_t *);
 867extern void        journal_update_sb_log_tail   (journal_t *, tid_t, unsigned int,
 868                                                 int);
 869extern void        journal_abort      (journal_t *, int);
 870extern int         journal_errno      (journal_t *);
 871extern void        journal_ack_err    (journal_t *);
 872extern int         journal_clear_err  (journal_t *);
 873extern int         journal_bmap(journal_t *, unsigned int, unsigned int *);
 874extern int         journal_force_commit(journal_t *);
 875
 876/*
 877 * journal_head management
 878 */
 879struct journal_head *journal_add_journal_head(struct buffer_head *bh);
 880struct journal_head *journal_grab_journal_head(struct buffer_head *bh);
 881void journal_put_journal_head(struct journal_head *jh);
 882
 883/*
 884 * handle management
 885 */
 886extern struct kmem_cache *jbd_handle_cache;
 887
 888static inline handle_t *jbd_alloc_handle(gfp_t gfp_flags)
 889{
 890        return kmem_cache_alloc(jbd_handle_cache, gfp_flags);
 891}
 892
 893static 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
 900extern int         journal_init_revoke(journal_t *, int);
 901extern void        journal_destroy_revoke_caches(void);
 902extern int         journal_init_revoke_caches(void);
 903
 904extern void        journal_destroy_revoke(journal_t *);
 905extern int         journal_revoke (handle_t *,
 906                                unsigned int, struct buffer_head *);
 907extern int         journal_cancel_revoke(handle_t *, struct journal_head *);
 908extern void        journal_write_revoke_records(journal_t *,
 909                                                transaction_t *, int);
 910
 911/* Recovery revoke support */
 912extern int      journal_set_revoke(journal_t *, unsigned int, tid_t);
 913extern int      journal_test_revoke(journal_t *, unsigned int, tid_t);
 914extern void     journal_clear_revoke(journal_t *);
 915extern void     journal_switch_revoke_table(journal_t *journal);
 916extern void     journal_clear_buffer_revoked_flags(journal_t *journal);
 917
 918/*
 919 * The log thread user interface:
 920 *
 921 * Request space in the current transaction, and force transaction commit
 922 * transitions on demand.
 923 */
 924
 925int __log_space_left(journal_t *); /* Called with journal locked */
 926int log_start_commit(journal_t *journal, tid_t tid);
 927int __log_start_commit(journal_t *journal, tid_t tid);
 928int journal_start_commit(journal_t *journal, tid_t *tid);
 929int journal_force_commit_nested(journal_t *journal);
 930int log_wait_commit(journal_t *journal, tid_t tid);
 931int log_do_checkpoint(journal_t *journal);
 932int journal_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
 933
 934void __log_wait_for_space(journal_t *journal);
 935extern void     __journal_drop_transaction(journal_t *, transaction_t *);
 936extern int      cleanup_journal_tail(journal_t *);
 937
 938/* Debugging code only: */
 939
 940#define jbd_ENOSYS() \
 941do {                                                                       \
 942        printk (KERN_ERR "JBD unimplemented function %s\n", __func__); \
 943        current->state = TASK_UNINTERRUPTIBLE;                             \
 944        schedule();                                                        \
 945} while (1)
 946
 947/*
 948 * is_journal_abort
 949 *
 950 * Simple test wrapper function to test the JFS_ABORT state flag.  This
 951 * bit, when set, indicates that we have had a fatal error somewhere,
 952 * either inside the journaling layer or indicated to us by the client
 953 * (eg. ext3), and that we and should not commit any further
 954 * transactions.
 955 */
 956
 957static inline int is_journal_aborted(journal_t *journal)
 958{
 959        return journal->j_flags & JFS_ABORT;
 960}
 961
 962static inline int is_handle_aborted(handle_t *handle)
 963{
 964        if (handle->h_aborted)
 965                return 1;
 966        return is_journal_aborted(handle->h_transaction->t_journal);
 967}
 968
 969static inline void journal_abort_handle(handle_t *handle)
 970{
 971        handle->h_aborted = 1;
 972}
 973
 974#endif /* __KERNEL__   */
 975
 976/* Comparison functions for transaction IDs: perform comparisons using
 977 * modulo arithmetic so that they work over sequence number wraps. */
 978
 979static inline int tid_gt(tid_t x, tid_t y)
 980{
 981        int difference = (x - y);
 982        return (difference > 0);
 983}
 984
 985static inline int tid_geq(tid_t x, tid_t y)
 986{
 987        int difference = (x - y);
 988        return (difference >= 0);
 989}
 990
 991extern int journal_blocks_per_page(struct inode *inode);
 992
 993/*
 994 * Return the minimum number of blocks which must be free in the journal
 995 * before a new transaction may be started.  Must be called under j_state_lock.
 996 */
 997static inline int jbd_space_needed(journal_t *journal)
 998{
 999        int nblocks = journal->j_max_transaction_buffers;
1000        if (journal->j_committing_transaction)
1001                nblocks += journal->j_committing_transaction->
1002                                        t_outstanding_credits;
1003        return nblocks;
1004}
1005
1006/*
1007 * Definitions which augment the buffer_head layer
1008 */
1009
1010/* journaling buffer types */
1011#define BJ_None         0       /* Not journaled */
1012#define BJ_SyncData     1       /* Normal data: flush before commit */
1013#define BJ_Metadata     2       /* Normal journaled metadata */
1014#define BJ_Forget       3       /* Buffer superseded by this transaction */
1015#define BJ_IO           4       /* Buffer is for temporary IO use */
1016#define BJ_Shadow       5       /* Buffer contents being shadowed to the log */
1017#define BJ_LogCtl       6       /* Buffer contains log descriptors */
1018#define BJ_Reserved     7       /* Buffer is reserved for access by journal */
1019#define BJ_Locked       8       /* Locked for I/O during commit */
1020#define BJ_Types        9
1021
1022extern int jbd_blocks_per_page(struct inode *inode);
1023
1024#ifdef __KERNEL__
1025
1026#define buffer_trace_init(bh)   do {} while (0)
1027#define print_buffer_fields(bh) do {} while (0)
1028#define print_buffer_trace(bh)  do {} while (0)
1029#define BUFFER_TRACE(bh, info)  do {} while (0)
1030#define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1031#define JBUFFER_TRACE(jh, info) do {} while (0)
1032
1033#endif  /* __KERNEL__ */
1034
1035#endif  /* _LINUX_JBD_H */
1036
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