linux/include/linux/jbd2.h
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   1/*
   2 * linux/include/linux/jbd2.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_JBD2_H
  17#define _LINUX_JBD2_H
  18
  19/* Allow this file to be included directly into e2fsprogs */
  20#ifndef __KERNEL__
  21#include "jfs_compat.h"
  22#define JBD2_DEBUG
  23#else
  24
  25#include <linux/types.h>
  26#include <linux/buffer_head.h>
  27#include <linux/journal-head.h>
  28#include <linux/stddef.h>
  29#include <linux/bit_spinlock.h>
  30#include <linux/mutex.h>
  31#include <linux/timer.h>
  32#include <linux/slab.h>
  33#include <crypto/hash.h>
  34#endif
  35
  36#define journal_oom_retry 1
  37
  38/*
  39 * Define JBD2_PARANIOD_IOFAIL to cause a kernel BUG() if ext4 finds
  40 * certain classes of error which can occur due to failed IOs.  Under
  41 * normal use we want ext4 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 JBD2_PARANOID_IOFAIL
  46
  47/*
  48 * The default maximum commit age, in seconds.
  49 */
  50#define JBD2_DEFAULT_MAX_COMMIT_AGE 5
  51
  52#ifdef CONFIG_JBD2_DEBUG
  53/*
  54 * Define JBD2_EXPENSIVE_CHECKING to enable more expensive internal
  55 * consistency checks.  By default we don't do this unless
  56 * CONFIG_JBD2_DEBUG is on.
  57 */
  58#define JBD2_EXPENSIVE_CHECKING
  59extern ushort jbd2_journal_enable_debug;
  60
  61#define jbd_debug(n, f, a...)                                           \
  62        do {                                                            \
  63                if ((n) <= jbd2_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
  73extern void *jbd2_alloc(size_t size, gfp_t flags);
  74extern void jbd2_free(void *ptr, size_t size);
  75
  76#define JBD2_MIN_JOURNAL_BLOCKS 1024
  77
  78#ifdef __KERNEL__
  79
  80/**
  81 * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.
  82 *
  83 * All filesystem modifications made by the process go
  84 * through this handle.  Recursive operations (such as quota operations)
  85 * are gathered into a single update.
  86 *
  87 * The buffer credits field is used to account for journaled buffers
  88 * being modified by the running process.  To ensure that there is
  89 * enough log space for all outstanding operations, we need to limit the
  90 * number of outstanding buffers possible at any time.  When the
  91 * operation completes, any buffer credits not used are credited back to
  92 * the transaction, so that at all times we know how many buffers the
  93 * outstanding updates on a transaction might possibly touch.
  94 *
  95 * This is an opaque datatype.
  96 **/
  97typedef struct jbd2_journal_handle handle_t;    /* Atomic operation type */
  98
  99
 100/**
 101 * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.
 102 *
 103 * journal_t is linked to from the fs superblock structure.
 104 *
 105 * We use the journal_t to keep track of all outstanding transaction
 106 * activity on the filesystem, and to manage the state of the log
 107 * writing process.
 108 *
 109 * This is an opaque datatype.
 110 **/
 111typedef struct journal_s        journal_t;      /* Journal control structure */
 112#endif
 113
 114/*
 115 * Internal structures used by the logging mechanism:
 116 */
 117
 118#define JBD2_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
 119
 120/*
 121 * On-disk structures
 122 */
 123
 124/*
 125 * Descriptor block types:
 126 */
 127
 128#define JBD2_DESCRIPTOR_BLOCK   1
 129#define JBD2_COMMIT_BLOCK       2
 130#define JBD2_SUPERBLOCK_V1      3
 131#define JBD2_SUPERBLOCK_V2      4
 132#define JBD2_REVOKE_BLOCK       5
 133
 134/*
 135 * Standard header for all descriptor blocks:
 136 */
 137typedef struct journal_header_s
 138{
 139        __be32          h_magic;
 140        __be32          h_blocktype;
 141        __be32          h_sequence;
 142} journal_header_t;
 143
 144/*
 145 * Checksum types.
 146 */
 147#define JBD2_CRC32_CHKSUM   1
 148#define JBD2_MD5_CHKSUM     2
 149#define JBD2_SHA1_CHKSUM    3
 150#define JBD2_CRC32C_CHKSUM  4
 151
 152#define JBD2_CRC32_CHKSUM_SIZE 4
 153
 154#define JBD2_CHECKSUM_BYTES (32 / sizeof(u32))
 155/*
 156 * Commit block header for storing transactional checksums:
 157 *
 158 * NOTE: If FEATURE_COMPAT_CHECKSUM (checksum v1) is set, the h_chksum*
 159 * fields are used to store a checksum of the descriptor and data blocks.
 160 *
 161 * If FEATURE_INCOMPAT_CSUM_V2 (checksum v2) is set, then the h_chksum
 162 * field is used to store crc32c(uuid+commit_block).  Each journal metadata
 163 * block gets its own checksum, and data block checksums are stored in
 164 * journal_block_tag (in the descriptor).  The other h_chksum* fields are
 165 * not used.
 166 *
 167 * Checksum v1 and v2 are mutually exclusive features.
 168 */
 169struct commit_header {
 170        __be32          h_magic;
 171        __be32          h_blocktype;
 172        __be32          h_sequence;
 173        unsigned char   h_chksum_type;
 174        unsigned char   h_chksum_size;
 175        unsigned char   h_padding[2];
 176        __be32          h_chksum[JBD2_CHECKSUM_BYTES];
 177        __be64          h_commit_sec;
 178        __be32          h_commit_nsec;
 179};
 180
 181/*
 182 * The block tag: used to describe a single buffer in the journal.
 183 * t_blocknr_high is only used if INCOMPAT_64BIT is set, so this
 184 * raw struct shouldn't be used for pointer math or sizeof() - use
 185 * journal_tag_bytes(journal) instead to compute this.
 186 */
 187typedef struct journal_block_tag_s
 188{
 189        __be32          t_blocknr;      /* The on-disk block number */
 190        __be16          t_checksum;     /* truncated crc32c(uuid+seq+block) */
 191        __be16          t_flags;        /* See below */
 192        __be32          t_blocknr_high; /* most-significant high 32bits. */
 193} journal_block_tag_t;
 194
 195#define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))
 196#define JBD2_TAG_SIZE64 (sizeof(journal_block_tag_t))
 197
 198/* Tail of descriptor block, for checksumming */
 199struct jbd2_journal_block_tail {
 200        __be32          t_checksum;     /* crc32c(uuid+descr_block) */
 201};
 202
 203/*
 204 * The revoke descriptor: used on disk to describe a series of blocks to
 205 * be revoked from the log
 206 */
 207typedef struct jbd2_journal_revoke_header_s
 208{
 209        journal_header_t r_header;
 210        __be32           r_count;       /* Count of bytes used in the block */
 211} jbd2_journal_revoke_header_t;
 212
 213/* Tail of revoke block, for checksumming */
 214struct jbd2_journal_revoke_tail {
 215        __be32          r_checksum;     /* crc32c(uuid+revoke_block) */
 216};
 217
 218/* Definitions for the journal tag flags word: */
 219#define JBD2_FLAG_ESCAPE                1       /* on-disk block is escaped */
 220#define JBD2_FLAG_SAME_UUID     2       /* block has same uuid as previous */
 221#define JBD2_FLAG_DELETED       4       /* block deleted by this transaction */
 222#define JBD2_FLAG_LAST_TAG      8       /* last tag in this descriptor block */
 223
 224
 225/*
 226 * The journal superblock.  All fields are in big-endian byte order.
 227 */
 228typedef struct journal_superblock_s
 229{
 230/* 0x0000 */
 231        journal_header_t s_header;
 232
 233/* 0x000C */
 234        /* Static information describing the journal */
 235        __be32  s_blocksize;            /* journal device blocksize */
 236        __be32  s_maxlen;               /* total blocks in journal file */
 237        __be32  s_first;                /* first block of log information */
 238
 239/* 0x0018 */
 240        /* Dynamic information describing the current state of the log */
 241        __be32  s_sequence;             /* first commit ID expected in log */
 242        __be32  s_start;                /* blocknr of start of log */
 243
 244/* 0x0020 */
 245        /* Error value, as set by jbd2_journal_abort(). */
 246        __be32  s_errno;
 247
 248/* 0x0024 */
 249        /* Remaining fields are only valid in a version-2 superblock */
 250        __be32  s_feature_compat;       /* compatible feature set */
 251        __be32  s_feature_incompat;     /* incompatible feature set */
 252        __be32  s_feature_ro_compat;    /* readonly-compatible feature set */
 253/* 0x0030 */
 254        __u8    s_uuid[16];             /* 128-bit uuid for journal */
 255
 256/* 0x0040 */
 257        __be32  s_nr_users;             /* Nr of filesystems sharing log */
 258
 259        __be32  s_dynsuper;             /* Blocknr of dynamic superblock copy*/
 260
 261/* 0x0048 */
 262        __be32  s_max_transaction;      /* Limit of journal blocks per trans.*/
 263        __be32  s_max_trans_data;       /* Limit of data blocks per trans. */
 264
 265/* 0x0050 */
 266        __u8    s_checksum_type;        /* checksum type */
 267        __u8    s_padding2[3];
 268        __u32   s_padding[42];
 269        __be32  s_checksum;             /* crc32c(superblock) */
 270
 271/* 0x0100 */
 272        __u8    s_users[16*48];         /* ids of all fs'es sharing the log */
 273/* 0x0400 */
 274} journal_superblock_t;
 275
 276#define JBD2_HAS_COMPAT_FEATURE(j,mask)                                 \
 277        ((j)->j_format_version >= 2 &&                                  \
 278         ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
 279#define JBD2_HAS_RO_COMPAT_FEATURE(j,mask)                              \
 280        ((j)->j_format_version >= 2 &&                                  \
 281         ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
 282#define JBD2_HAS_INCOMPAT_FEATURE(j,mask)                               \
 283        ((j)->j_format_version >= 2 &&                                  \
 284         ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
 285
 286#define JBD2_FEATURE_COMPAT_CHECKSUM    0x00000001
 287
 288#define JBD2_FEATURE_INCOMPAT_REVOKE            0x00000001
 289#define JBD2_FEATURE_INCOMPAT_64BIT             0x00000002
 290#define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT      0x00000004
 291#define JBD2_FEATURE_INCOMPAT_CSUM_V2           0x00000008
 292
 293/* Features known to this kernel version: */
 294#define JBD2_KNOWN_COMPAT_FEATURES      JBD2_FEATURE_COMPAT_CHECKSUM
 295#define JBD2_KNOWN_ROCOMPAT_FEATURES    0
 296#define JBD2_KNOWN_INCOMPAT_FEATURES    (JBD2_FEATURE_INCOMPAT_REVOKE | \
 297                                        JBD2_FEATURE_INCOMPAT_64BIT | \
 298                                        JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT | \
 299                                        JBD2_FEATURE_INCOMPAT_CSUM_V2)
 300
 301#ifdef __KERNEL__
 302
 303#include <linux/fs.h>
 304#include <linux/sched.h>
 305#include <linux/jbd_common.h>
 306
 307#define J_ASSERT(assert)        BUG_ON(!(assert))
 308
 309#define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
 310#define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
 311
 312#if defined(JBD2_PARANOID_IOFAIL)
 313#define J_EXPECT(expr, why...)          J_ASSERT(expr)
 314#define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
 315#define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
 316#else
 317#define __journal_expect(expr, why...)                                       \
 318        ({                                                                   \
 319                int val = (expr);                                            \
 320                if (!val) {                                                  \
 321                        printk(KERN_ERR                                      \
 322                               "JBD2 unexpected failure: %s: %s;\n",         \
 323                               __func__, #expr);                             \
 324                        printk(KERN_ERR why "\n");                           \
 325                }                                                            \
 326                val;                                                         \
 327        })
 328#define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)
 329#define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)
 330#define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)
 331#endif
 332
 333/* Flags in jbd_inode->i_flags */
 334#define __JI_COMMIT_RUNNING 0
 335/* Commit of the inode data in progress. We use this flag to protect us from
 336 * concurrent deletion of inode. We cannot use reference to inode for this
 337 * since we cannot afford doing last iput() on behalf of kjournald
 338 */
 339#define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING)
 340
 341/**
 342 * struct jbd_inode is the structure linking inodes in ordered mode
 343 *   present in a transaction so that we can sync them during commit.
 344 */
 345struct jbd2_inode {
 346        /* Which transaction does this inode belong to? Either the running
 347         * transaction or the committing one. [j_list_lock] */
 348        transaction_t *i_transaction;
 349
 350        /* Pointer to the running transaction modifying inode's data in case
 351         * there is already a committing transaction touching it. [j_list_lock] */
 352        transaction_t *i_next_transaction;
 353
 354        /* List of inodes in the i_transaction [j_list_lock] */
 355        struct list_head i_list;
 356
 357        /* VFS inode this inode belongs to [constant during the lifetime
 358         * of the structure] */
 359        struct inode *i_vfs_inode;
 360
 361        /* Flags of inode [j_list_lock] */
 362        unsigned long i_flags;
 363};
 364
 365struct jbd2_revoke_table_s;
 366
 367/**
 368 * struct handle_s - The handle_s type is the concrete type associated with
 369 *     handle_t.
 370 * @h_transaction: Which compound transaction is this update a part of?
 371 * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
 372 * @h_ref: Reference count on this handle
 373 * @h_err: Field for caller's use to track errors through large fs operations
 374 * @h_sync: flag for sync-on-close
 375 * @h_jdata: flag to force data journaling
 376 * @h_aborted: flag indicating fatal error on handle
 377 **/
 378
 379/* Docbook can't yet cope with the bit fields, but will leave the documentation
 380 * in so it can be fixed later.
 381 */
 382
 383struct jbd2_journal_handle
 384{
 385        /* Which compound transaction is this update a part of? */
 386        transaction_t           *h_transaction;
 387
 388        /* Number of remaining buffers we are allowed to dirty: */
 389        int                     h_buffer_credits;
 390
 391        /* Reference count on this handle */
 392        int                     h_ref;
 393
 394        /* Field for caller's use to track errors through large fs */
 395        /* operations */
 396        int                     h_err;
 397
 398        /* Flags [no locking] */
 399        unsigned int    h_sync:         1;      /* sync-on-close */
 400        unsigned int    h_jdata:        1;      /* force data journaling */
 401        unsigned int    h_aborted:      1;      /* fatal error on handle */
 402        unsigned int    h_type:         8;      /* for handle statistics */
 403        unsigned int    h_line_no:      16;     /* for handle statistics */
 404
 405        unsigned long           h_start_jiffies;
 406        unsigned int            h_requested_credits;
 407
 408#ifdef CONFIG_DEBUG_LOCK_ALLOC
 409        struct lockdep_map      h_lockdep_map;
 410#endif
 411};
 412
 413
 414/*
 415 * Some stats for checkpoint phase
 416 */
 417struct transaction_chp_stats_s {
 418        unsigned long           cs_chp_time;
 419        __u32                   cs_forced_to_close;
 420        __u32                   cs_written;
 421        __u32                   cs_dropped;
 422};
 423
 424/* The transaction_t type is the guts of the journaling mechanism.  It
 425 * tracks a compound transaction through its various states:
 426 *
 427 * RUNNING:     accepting new updates
 428 * LOCKED:      Updates still running but we don't accept new ones
 429 * RUNDOWN:     Updates are tidying up but have finished requesting
 430 *              new buffers to modify (state not used for now)
 431 * FLUSH:       All updates complete, but we are still writing to disk
 432 * COMMIT:      All data on disk, writing commit record
 433 * FINISHED:    We still have to keep the transaction for checkpointing.
 434 *
 435 * The transaction keeps track of all of the buffers modified by a
 436 * running transaction, and all of the buffers committed but not yet
 437 * flushed to home for finished transactions.
 438 */
 439
 440/*
 441 * Lock ranking:
 442 *
 443 *    j_list_lock
 444 *      ->jbd_lock_bh_journal_head()    (This is "innermost")
 445 *
 446 *    j_state_lock
 447 *    ->jbd_lock_bh_state()
 448 *
 449 *    jbd_lock_bh_state()
 450 *    ->j_list_lock
 451 *
 452 *    j_state_lock
 453 *    ->t_handle_lock
 454 *
 455 *    j_state_lock
 456 *    ->j_list_lock                     (journal_unmap_buffer)
 457 *
 458 */
 459
 460struct transaction_s
 461{
 462        /* Pointer to the journal for this transaction. [no locking] */
 463        journal_t               *t_journal;
 464
 465        /* Sequence number for this transaction [no locking] */
 466        tid_t                   t_tid;
 467
 468        /*
 469         * Transaction's current state
 470         * [no locking - only kjournald2 alters this]
 471         * [j_list_lock] guards transition of a transaction into T_FINISHED
 472         * state and subsequent call of __jbd2_journal_drop_transaction()
 473         * FIXME: needs barriers
 474         * KLUDGE: [use j_state_lock]
 475         */
 476        enum {
 477                T_RUNNING,
 478                T_LOCKED,
 479                T_FLUSH,
 480                T_COMMIT,
 481                T_COMMIT_DFLUSH,
 482                T_COMMIT_JFLUSH,
 483                T_COMMIT_CALLBACK,
 484                T_FINISHED
 485        }                       t_state;
 486
 487        /*
 488         * Where in the log does this transaction's commit start? [no locking]
 489         */
 490        unsigned long           t_log_start;
 491
 492        /* Number of buffers on the t_buffers list [j_list_lock] */
 493        int                     t_nr_buffers;
 494
 495        /*
 496         * Doubly-linked circular list of all buffers reserved but not yet
 497         * modified by this transaction [j_list_lock]
 498         */
 499        struct journal_head     *t_reserved_list;
 500
 501        /*
 502         * Doubly-linked circular list of all metadata buffers owned by this
 503         * transaction [j_list_lock]
 504         */
 505        struct journal_head     *t_buffers;
 506
 507        /*
 508         * Doubly-linked circular list of all forget buffers (superseded
 509         * buffers which we can un-checkpoint once this transaction commits)
 510         * [j_list_lock]
 511         */
 512        struct journal_head     *t_forget;
 513
 514        /*
 515         * Doubly-linked circular list of all buffers still to be flushed before
 516         * this transaction can be checkpointed. [j_list_lock]
 517         */
 518        struct journal_head     *t_checkpoint_list;
 519
 520        /*
 521         * Doubly-linked circular list of all buffers submitted for IO while
 522         * checkpointing. [j_list_lock]
 523         */
 524        struct journal_head     *t_checkpoint_io_list;
 525
 526        /*
 527         * Doubly-linked circular list of temporary buffers currently undergoing
 528         * IO in the log [j_list_lock]
 529         */
 530        struct journal_head     *t_iobuf_list;
 531
 532        /*
 533         * Doubly-linked circular list of metadata buffers being shadowed by log
 534         * IO.  The IO buffers on the iobuf list and the shadow buffers on this
 535         * list match each other one for one at all times. [j_list_lock]
 536         */
 537        struct journal_head     *t_shadow_list;
 538
 539        /*
 540         * Doubly-linked circular list of control buffers being written to the
 541         * log. [j_list_lock]
 542         */
 543        struct journal_head     *t_log_list;
 544
 545        /*
 546         * List of inodes whose data we've modified in data=ordered mode.
 547         * [j_list_lock]
 548         */
 549        struct list_head        t_inode_list;
 550
 551        /*
 552         * Protects info related to handles
 553         */
 554        spinlock_t              t_handle_lock;
 555
 556        /*
 557         * Longest time some handle had to wait for running transaction
 558         */
 559        unsigned long           t_max_wait;
 560
 561        /*
 562         * When transaction started
 563         */
 564        unsigned long           t_start;
 565
 566        /*
 567         * When commit was requested
 568         */
 569        unsigned long           t_requested;
 570
 571        /*
 572         * Checkpointing stats [j_checkpoint_sem]
 573         */
 574        struct transaction_chp_stats_s t_chp_stats;
 575
 576        /*
 577         * Number of outstanding updates running on this transaction
 578         * [t_handle_lock]
 579         */
 580        atomic_t                t_updates;
 581
 582        /*
 583         * Number of buffers reserved for use by all handles in this transaction
 584         * handle but not yet modified. [t_handle_lock]
 585         */
 586        atomic_t                t_outstanding_credits;
 587
 588        /*
 589         * Forward and backward links for the circular list of all transactions
 590         * awaiting checkpoint. [j_list_lock]
 591         */
 592        transaction_t           *t_cpnext, *t_cpprev;
 593
 594        /*
 595         * When will the transaction expire (become due for commit), in jiffies?
 596         * [no locking]
 597         */
 598        unsigned long           t_expires;
 599
 600        /*
 601         * When this transaction started, in nanoseconds [no locking]
 602         */
 603        ktime_t                 t_start_time;
 604
 605        /*
 606         * How many handles used this transaction? [t_handle_lock]
 607         */
 608        atomic_t                t_handle_count;
 609
 610        /*
 611         * This transaction is being forced and some process is
 612         * waiting for it to finish.
 613         */
 614        unsigned int t_synchronous_commit:1;
 615
 616        /* Disk flush needs to be sent to fs partition [no locking] */
 617        int                     t_need_data_flush;
 618
 619        /*
 620         * For use by the filesystem to store fs-specific data
 621         * structures associated with the transaction
 622         */
 623        struct list_head        t_private_list;
 624};
 625
 626struct transaction_run_stats_s {
 627        unsigned long           rs_wait;
 628        unsigned long           rs_request_delay;
 629        unsigned long           rs_running;
 630        unsigned long           rs_locked;
 631        unsigned long           rs_flushing;
 632        unsigned long           rs_logging;
 633
 634        __u32                   rs_handle_count;
 635        __u32                   rs_blocks;
 636        __u32                   rs_blocks_logged;
 637};
 638
 639struct transaction_stats_s {
 640        unsigned long           ts_tid;
 641        unsigned long           ts_requested;
 642        struct transaction_run_stats_s run;
 643};
 644
 645static inline unsigned long
 646jbd2_time_diff(unsigned long start, unsigned long end)
 647{
 648        if (end >= start)
 649                return end - start;
 650
 651        return end + (MAX_JIFFY_OFFSET - start);
 652}
 653
 654#define JBD2_NR_BATCH   64
 655
 656/**
 657 * struct journal_s - The journal_s type is the concrete type associated with
 658 *     journal_t.
 659 * @j_flags:  General journaling state flags
 660 * @j_errno:  Is there an outstanding uncleared error on the journal (from a
 661 *     prior abort)?
 662 * @j_sb_buffer: First part of superblock buffer
 663 * @j_superblock: Second part of superblock buffer
 664 * @j_format_version: Version of the superblock format
 665 * @j_state_lock: Protect the various scalars in the journal
 666 * @j_barrier_count:  Number of processes waiting to create a barrier lock
 667 * @j_barrier: The barrier lock itself
 668 * @j_running_transaction: The current running transaction..
 669 * @j_committing_transaction: the transaction we are pushing to disk
 670 * @j_checkpoint_transactions: a linked circular list of all transactions
 671 *  waiting for checkpointing
 672 * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
 673 *  to start committing, or for a barrier lock to be released
 674 * @j_wait_logspace: Wait queue for waiting for checkpointing to complete
 675 * @j_wait_done_commit: Wait queue for waiting for commit to complete
 676 * @j_wait_checkpoint:  Wait queue to trigger checkpointing
 677 * @j_wait_commit: Wait queue to trigger commit
 678 * @j_wait_updates: Wait queue to wait for updates to complete
 679 * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
 680 * @j_head: Journal head - identifies the first unused block in the journal
 681 * @j_tail: Journal tail - identifies the oldest still-used block in the
 682 *  journal.
 683 * @j_free: Journal free - how many free blocks are there in the journal?
 684 * @j_first: The block number of the first usable block
 685 * @j_last: The block number one beyond the last usable block
 686 * @j_dev: Device where we store the journal
 687 * @j_blocksize: blocksize for the location where we store the journal.
 688 * @j_blk_offset: starting block offset for into the device where we store the
 689 *     journal
 690 * @j_fs_dev: Device which holds the client fs.  For internal journal this will
 691 *     be equal to j_dev
 692 * @j_maxlen: Total maximum capacity of the journal region on disk.
 693 * @j_list_lock: Protects the buffer lists and internal buffer state.
 694 * @j_inode: Optional inode where we store the journal.  If present, all journal
 695 *     block numbers are mapped into this inode via bmap().
 696 * @j_tail_sequence:  Sequence number of the oldest transaction in the log
 697 * @j_transaction_sequence: Sequence number of the next transaction to grant
 698 * @j_commit_sequence: Sequence number of the most recently committed
 699 *  transaction
 700 * @j_commit_request: Sequence number of the most recent transaction wanting
 701 *     commit
 702 * @j_uuid: Uuid of client object.
 703 * @j_task: Pointer to the current commit thread for this journal
 704 * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
 705 *     single compound commit transaction
 706 * @j_commit_interval: What is the maximum transaction lifetime before we begin
 707 *  a commit?
 708 * @j_commit_timer:  The timer used to wakeup the commit thread
 709 * @j_revoke_lock: Protect the revoke table
 710 * @j_revoke: The revoke table - maintains the list of revoked blocks in the
 711 *     current transaction.
 712 * @j_revoke_table: alternate revoke tables for j_revoke
 713 * @j_wbuf: array of buffer_heads for jbd2_journal_commit_transaction
 714 * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
 715 *      number that will fit in j_blocksize
 716 * @j_last_sync_writer: most recent pid which did a synchronous write
 717 * @j_history: Buffer storing the transactions statistics history
 718 * @j_history_max: Maximum number of transactions in the statistics history
 719 * @j_history_cur: Current number of transactions in the statistics history
 720 * @j_history_lock: Protect the transactions statistics history
 721 * @j_proc_entry: procfs entry for the jbd statistics directory
 722 * @j_stats: Overall statistics
 723 * @j_private: An opaque pointer to fs-private information.
 724 */
 725
 726struct journal_s
 727{
 728        /* General journaling state flags [j_state_lock] */
 729        unsigned long           j_flags;
 730
 731        /*
 732         * Is there an outstanding uncleared error on the journal (from a prior
 733         * abort)? [j_state_lock]
 734         */
 735        int                     j_errno;
 736
 737        /* The superblock buffer */
 738        struct buffer_head      *j_sb_buffer;
 739        journal_superblock_t    *j_superblock;
 740
 741        /* Version of the superblock format */
 742        int                     j_format_version;
 743
 744        /*
 745         * Protect the various scalars in the journal
 746         */
 747        rwlock_t                j_state_lock;
 748
 749        /*
 750         * Number of processes waiting to create a barrier lock [j_state_lock]
 751         */
 752        int                     j_barrier_count;
 753
 754        /* The barrier lock itself */
 755        struct mutex            j_barrier;
 756
 757        /*
 758         * Transactions: The current running transaction...
 759         * [j_state_lock] [caller holding open handle]
 760         */
 761        transaction_t           *j_running_transaction;
 762
 763        /*
 764         * the transaction we are pushing to disk
 765         * [j_state_lock] [caller holding open handle]
 766         */
 767        transaction_t           *j_committing_transaction;
 768
 769        /*
 770         * ... and a linked circular list of all transactions waiting for
 771         * checkpointing. [j_list_lock]
 772         */
 773        transaction_t           *j_checkpoint_transactions;
 774
 775        /*
 776         * Wait queue for waiting for a locked transaction to start committing,
 777         * or for a barrier lock to be released
 778         */
 779        wait_queue_head_t       j_wait_transaction_locked;
 780
 781        /* Wait queue for waiting for checkpointing to complete */
 782        wait_queue_head_t       j_wait_logspace;
 783
 784        /* Wait queue for waiting for commit to complete */
 785        wait_queue_head_t       j_wait_done_commit;
 786
 787        /* Wait queue to trigger checkpointing */
 788        wait_queue_head_t       j_wait_checkpoint;
 789
 790        /* Wait queue to trigger commit */
 791        wait_queue_head_t       j_wait_commit;
 792
 793        /* Wait queue to wait for updates to complete */
 794        wait_queue_head_t       j_wait_updates;
 795
 796        /* Semaphore for locking against concurrent checkpoints */
 797        struct mutex            j_checkpoint_mutex;
 798
 799        /*
 800         * List of buffer heads used by the checkpoint routine.  This
 801         * was moved from jbd2_log_do_checkpoint() to reduce stack
 802         * usage.  Access to this array is controlled by the
 803         * j_checkpoint_mutex.  [j_checkpoint_mutex]
 804         */
 805        struct buffer_head      *j_chkpt_bhs[JBD2_NR_BATCH];
 806        
 807        /*
 808         * Journal head: identifies the first unused block in the journal.
 809         * [j_state_lock]
 810         */
 811        unsigned long           j_head;
 812
 813        /*
 814         * Journal tail: identifies the oldest still-used block in the journal.
 815         * [j_state_lock]
 816         */
 817        unsigned long           j_tail;
 818
 819        /*
 820         * Journal free: how many free blocks are there in the journal?
 821         * [j_state_lock]
 822         */
 823        unsigned long           j_free;
 824
 825        /*
 826         * Journal start and end: the block numbers of the first usable block
 827         * and one beyond the last usable block in the journal. [j_state_lock]
 828         */
 829        unsigned long           j_first;
 830        unsigned long           j_last;
 831
 832        /*
 833         * Device, blocksize and starting block offset for the location where we
 834         * store the journal.
 835         */
 836        struct block_device     *j_dev;
 837        int                     j_blocksize;
 838        unsigned long long      j_blk_offset;
 839        char                    j_devname[BDEVNAME_SIZE+24];
 840
 841        /*
 842         * Device which holds the client fs.  For internal journal this will be
 843         * equal to j_dev.
 844         */
 845        struct block_device     *j_fs_dev;
 846
 847        /* Total maximum capacity of the journal region on disk. */
 848        unsigned int            j_maxlen;
 849
 850        /*
 851         * Protects the buffer lists and internal buffer state.
 852         */
 853        spinlock_t              j_list_lock;
 854
 855        /* Optional inode where we store the journal.  If present, all */
 856        /* journal block numbers are mapped into this inode via */
 857        /* bmap(). */
 858        struct inode            *j_inode;
 859
 860        /*
 861         * Sequence number of the oldest transaction in the log [j_state_lock]
 862         */
 863        tid_t                   j_tail_sequence;
 864
 865        /*
 866         * Sequence number of the next transaction to grant [j_state_lock]
 867         */
 868        tid_t                   j_transaction_sequence;
 869
 870        /*
 871         * Sequence number of the most recently committed transaction
 872         * [j_state_lock].
 873         */
 874        tid_t                   j_commit_sequence;
 875
 876        /*
 877         * Sequence number of the most recent transaction wanting commit
 878         * [j_state_lock]
 879         */
 880        tid_t                   j_commit_request;
 881
 882        /*
 883         * Journal uuid: identifies the object (filesystem, LVM volume etc)
 884         * backed by this journal.  This will eventually be replaced by an array
 885         * of uuids, allowing us to index multiple devices within a single
 886         * journal and to perform atomic updates across them.
 887         */
 888        __u8                    j_uuid[16];
 889
 890        /* Pointer to the current commit thread for this journal */
 891        struct task_struct      *j_task;
 892
 893        /*
 894         * Maximum number of metadata buffers to allow in a single compound
 895         * commit transaction
 896         */
 897        int                     j_max_transaction_buffers;
 898
 899        /*
 900         * What is the maximum transaction lifetime before we begin a commit?
 901         */
 902        unsigned long           j_commit_interval;
 903
 904        /* The timer used to wakeup the commit thread: */
 905        struct timer_list       j_commit_timer;
 906
 907        /*
 908         * The revoke table: maintains the list of revoked blocks in the
 909         * current transaction.  [j_revoke_lock]
 910         */
 911        spinlock_t              j_revoke_lock;
 912        struct jbd2_revoke_table_s *j_revoke;
 913        struct jbd2_revoke_table_s *j_revoke_table[2];
 914
 915        /*
 916         * array of bhs for jbd2_journal_commit_transaction
 917         */
 918        struct buffer_head      **j_wbuf;
 919        int                     j_wbufsize;
 920
 921        /*
 922         * this is the pid of hte last person to run a synchronous operation
 923         * through the journal
 924         */
 925        pid_t                   j_last_sync_writer;
 926
 927        /*
 928         * the average amount of time in nanoseconds it takes to commit a
 929         * transaction to disk. [j_state_lock]
 930         */
 931        u64                     j_average_commit_time;
 932
 933        /*
 934         * minimum and maximum times that we should wait for
 935         * additional filesystem operations to get batched into a
 936         * synchronous handle in microseconds
 937         */
 938        u32                     j_min_batch_time;
 939        u32                     j_max_batch_time;
 940
 941        /* This function is called when a transaction is closed */
 942        void                    (*j_commit_callback)(journal_t *,
 943                                                     transaction_t *);
 944
 945        /*
 946         * Journal statistics
 947         */
 948        spinlock_t              j_history_lock;
 949        struct proc_dir_entry   *j_proc_entry;
 950        struct transaction_stats_s j_stats;
 951
 952        /* Failed journal commit ID */
 953        unsigned int            j_failed_commit;
 954
 955        /*
 956         * An opaque pointer to fs-private information.  ext3 puts its
 957         * superblock pointer here
 958         */
 959        void *j_private;
 960
 961        /* Reference to checksum algorithm driver via cryptoapi */
 962        struct crypto_shash *j_chksum_driver;
 963
 964        /* Precomputed journal UUID checksum for seeding other checksums */
 965        __u32 j_csum_seed;
 966};
 967
 968/*
 969 * Journal flag definitions
 970 */
 971#define JBD2_UNMOUNT    0x001   /* Journal thread is being destroyed */
 972#define JBD2_ABORT      0x002   /* Journaling has been aborted for errors. */
 973#define JBD2_ACK_ERR    0x004   /* The errno in the sb has been acked */
 974#define JBD2_FLUSHED    0x008   /* The journal superblock has been flushed */
 975#define JBD2_LOADED     0x010   /* The journal superblock has been loaded */
 976#define JBD2_BARRIER    0x020   /* Use IDE barriers */
 977#define JBD2_ABORT_ON_SYNCDATA_ERR      0x040   /* Abort the journal on file
 978                                                 * data write error in ordered
 979                                                 * mode */
 980
 981/*
 982 * Function declarations for the journaling transaction and buffer
 983 * management
 984 */
 985
 986/* Filing buffers */
 987extern void jbd2_journal_unfile_buffer(journal_t *, struct journal_head *);
 988extern void __jbd2_journal_refile_buffer(struct journal_head *);
 989extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *);
 990extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
 991extern void __journal_free_buffer(struct journal_head *bh);
 992extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
 993extern void __journal_clean_data_list(transaction_t *transaction);
 994
 995/* Log buffer allocation */
 996extern struct journal_head * jbd2_journal_get_descriptor_buffer(journal_t *);
 997int jbd2_journal_next_log_block(journal_t *, unsigned long long *);
 998int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
 999                              unsigned long *block);
1000void __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1001void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1002
1003/* Commit management */
1004extern void jbd2_journal_commit_transaction(journal_t *);
1005
1006/* Checkpoint list management */
1007int __jbd2_journal_clean_checkpoint_list(journal_t *journal);
1008int __jbd2_journal_remove_checkpoint(struct journal_head *);
1009void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
1010
1011
1012/*
1013 * Triggers
1014 */
1015
1016struct jbd2_buffer_trigger_type {
1017        /*
1018         * Fired a the moment data to write to the journal are known to be
1019         * stable - so either at the moment b_frozen_data is created or just
1020         * before a buffer is written to the journal.  mapped_data is a mapped
1021         * buffer that is the frozen data for commit.
1022         */
1023        void (*t_frozen)(struct jbd2_buffer_trigger_type *type,
1024                         struct buffer_head *bh, void *mapped_data,
1025                         size_t size);
1026
1027        /*
1028         * Fired during journal abort for dirty buffers that will not be
1029         * committed.
1030         */
1031        void (*t_abort)(struct jbd2_buffer_trigger_type *type,
1032                        struct buffer_head *bh);
1033};
1034
1035extern void jbd2_buffer_frozen_trigger(struct journal_head *jh,
1036                                       void *mapped_data,
1037                                       struct jbd2_buffer_trigger_type *triggers);
1038extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
1039                                      struct jbd2_buffer_trigger_type *triggers);
1040
1041/* Buffer IO */
1042extern int
1043jbd2_journal_write_metadata_buffer(transaction_t          *transaction,
1044                              struct journal_head  *jh_in,
1045                              struct journal_head **jh_out,
1046                              unsigned long long   blocknr);
1047
1048/* Transaction locking */
1049extern void             __wait_on_journal (journal_t *);
1050
1051/* Transaction cache support */
1052extern void jbd2_journal_destroy_transaction_cache(void);
1053extern int  jbd2_journal_init_transaction_cache(void);
1054extern void jbd2_journal_free_transaction(transaction_t *);
1055
1056/*
1057 * Journal locking.
1058 *
1059 * We need to lock the journal during transaction state changes so that nobody
1060 * ever tries to take a handle on the running transaction while we are in the
1061 * middle of moving it to the commit phase.  j_state_lock does this.
1062 *
1063 * Note that the locking is completely interrupt unsafe.  We never touch
1064 * journal structures from interrupts.
1065 */
1066
1067static inline handle_t *journal_current_handle(void)
1068{
1069        return current->journal_info;
1070}
1071
1072/* The journaling code user interface:
1073 *
1074 * Create and destroy handles
1075 * Register buffer modifications against the current transaction.
1076 */
1077
1078extern handle_t *jbd2_journal_start(journal_t *, int nblocks);
1079extern handle_t *jbd2__journal_start(journal_t *, int nblocks, gfp_t gfp_mask,
1080                                     unsigned int type, unsigned int line_no);
1081extern int       jbd2_journal_restart(handle_t *, int nblocks);
1082extern int       jbd2__journal_restart(handle_t *, int nblocks, gfp_t gfp_mask);
1083extern int       jbd2_journal_extend (handle_t *, int nblocks);
1084extern int       jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
1085extern int       jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
1086extern int       jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
1087void             jbd2_journal_set_triggers(struct buffer_head *,
1088                                           struct jbd2_buffer_trigger_type *type);
1089extern int       jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
1090extern int       jbd2_journal_forget (handle_t *, struct buffer_head *);
1091extern void      journal_sync_buffer (struct buffer_head *);
1092extern int       jbd2_journal_invalidatepage(journal_t *,
1093                                struct page *, unsigned long);
1094extern int       jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
1095extern int       jbd2_journal_stop(handle_t *);
1096extern int       jbd2_journal_flush (journal_t *);
1097extern void      jbd2_journal_lock_updates (journal_t *);
1098extern void      jbd2_journal_unlock_updates (journal_t *);
1099
1100extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1101                                struct block_device *fs_dev,
1102                                unsigned long long start, int len, int bsize);
1103extern journal_t * jbd2_journal_init_inode (struct inode *);
1104extern int         jbd2_journal_update_format (journal_t *);
1105extern int         jbd2_journal_check_used_features
1106                   (journal_t *, unsigned long, unsigned long, unsigned long);
1107extern int         jbd2_journal_check_available_features
1108                   (journal_t *, unsigned long, unsigned long, unsigned long);
1109extern int         jbd2_journal_set_features
1110                   (journal_t *, unsigned long, unsigned long, unsigned long);
1111extern void        jbd2_journal_clear_features
1112                   (journal_t *, unsigned long, unsigned long, unsigned long);
1113extern int         jbd2_journal_load       (journal_t *journal);
1114extern int         jbd2_journal_destroy    (journal_t *);
1115extern int         jbd2_journal_recover    (journal_t *journal);
1116extern int         jbd2_journal_wipe       (journal_t *, int);
1117extern int         jbd2_journal_skip_recovery   (journal_t *);
1118extern void        jbd2_journal_update_sb_errno(journal_t *);
1119extern void        jbd2_journal_update_sb_log_tail      (journal_t *, tid_t,
1120                                unsigned long, int);
1121extern void        __jbd2_journal_abort_hard    (journal_t *);
1122extern void        jbd2_journal_abort      (journal_t *, int);
1123extern int         jbd2_journal_errno      (journal_t *);
1124extern void        jbd2_journal_ack_err    (journal_t *);
1125extern int         jbd2_journal_clear_err  (journal_t *);
1126extern int         jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
1127extern int         jbd2_journal_force_commit(journal_t *);
1128extern int         jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *inode);
1129extern int         jbd2_journal_begin_ordered_truncate(journal_t *journal,
1130                                struct jbd2_inode *inode, loff_t new_size);
1131extern void        jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);
1132extern void        jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode);
1133
1134/*
1135 * journal_head management
1136 */
1137struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh);
1138struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh);
1139void jbd2_journal_put_journal_head(struct journal_head *jh);
1140
1141/*
1142 * handle management
1143 */
1144extern struct kmem_cache *jbd2_handle_cache;
1145
1146static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags)
1147{
1148        return kmem_cache_alloc(jbd2_handle_cache, gfp_flags);
1149}
1150
1151static inline void jbd2_free_handle(handle_t *handle)
1152{
1153        kmem_cache_free(jbd2_handle_cache, handle);
1154}
1155
1156/*
1157 * jbd2_inode management (optional, for those file systems that want to use
1158 * dynamically allocated jbd2_inode structures)
1159 */
1160extern struct kmem_cache *jbd2_inode_cache;
1161
1162static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags)
1163{
1164        return kmem_cache_alloc(jbd2_inode_cache, gfp_flags);
1165}
1166
1167static inline void jbd2_free_inode(struct jbd2_inode *jinode)
1168{
1169        kmem_cache_free(jbd2_inode_cache, jinode);
1170}
1171
1172/* Primary revoke support */
1173#define JOURNAL_REVOKE_DEFAULT_HASH 256
1174extern int         jbd2_journal_init_revoke(journal_t *, int);
1175extern void        jbd2_journal_destroy_revoke_caches(void);
1176extern int         jbd2_journal_init_revoke_caches(void);
1177
1178extern void        jbd2_journal_destroy_revoke(journal_t *);
1179extern int         jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *);
1180extern int         jbd2_journal_cancel_revoke(handle_t *, struct journal_head *);
1181extern void        jbd2_journal_write_revoke_records(journal_t *,
1182                                                     transaction_t *, int);
1183
1184/* Recovery revoke support */
1185extern int      jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t);
1186extern int      jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t);
1187extern void     jbd2_journal_clear_revoke(journal_t *);
1188extern void     jbd2_journal_switch_revoke_table(journal_t *journal);
1189extern void     jbd2_clear_buffer_revoked_flags(journal_t *journal);
1190
1191/*
1192 * The log thread user interface:
1193 *
1194 * Request space in the current transaction, and force transaction commit
1195 * transitions on demand.
1196 */
1197
1198int __jbd2_log_space_left(journal_t *); /* Called with journal locked */
1199int jbd2_log_start_commit(journal_t *journal, tid_t tid);
1200int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
1201int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
1202int jbd2_journal_force_commit_nested(journal_t *journal);
1203int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
1204int jbd2_complete_transaction(journal_t *journal, tid_t tid);
1205int jbd2_log_do_checkpoint(journal_t *journal);
1206int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
1207
1208void __jbd2_log_wait_for_space(journal_t *journal);
1209extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
1210extern int jbd2_cleanup_journal_tail(journal_t *);
1211
1212/* Debugging code only: */
1213
1214#define jbd_ENOSYS() \
1215do {                                                                       \
1216        printk (KERN_ERR "JBD unimplemented function %s\n", __func__); \
1217        current->state = TASK_UNINTERRUPTIBLE;                             \
1218        schedule();                                                        \
1219} while (1)
1220
1221/*
1222 * is_journal_abort
1223 *
1224 * Simple test wrapper function to test the JBD2_ABORT state flag.  This
1225 * bit, when set, indicates that we have had a fatal error somewhere,
1226 * either inside the journaling layer or indicated to us by the client
1227 * (eg. ext3), and that we and should not commit any further
1228 * transactions.
1229 */
1230
1231static inline int is_journal_aborted(journal_t *journal)
1232{
1233        return journal->j_flags & JBD2_ABORT;
1234}
1235
1236static inline int is_handle_aborted(handle_t *handle)
1237{
1238        if (handle->h_aborted)
1239                return 1;
1240        return is_journal_aborted(handle->h_transaction->t_journal);
1241}
1242
1243static inline void jbd2_journal_abort_handle(handle_t *handle)
1244{
1245        handle->h_aborted = 1;
1246}
1247
1248#endif /* __KERNEL__   */
1249
1250/* Comparison functions for transaction IDs: perform comparisons using
1251 * modulo arithmetic so that they work over sequence number wraps. */
1252
1253static inline int tid_gt(tid_t x, tid_t y)
1254{
1255        int difference = (x - y);
1256        return (difference > 0);
1257}
1258
1259static inline int tid_geq(tid_t x, tid_t y)
1260{
1261        int difference = (x - y);
1262        return (difference >= 0);
1263}
1264
1265extern int jbd2_journal_blocks_per_page(struct inode *inode);
1266extern size_t journal_tag_bytes(journal_t *journal);
1267
1268/*
1269 * Return the minimum number of blocks which must be free in the journal
1270 * before a new transaction may be started.  Must be called under j_state_lock.
1271 */
1272static inline int jbd_space_needed(journal_t *journal)
1273{
1274        int nblocks = journal->j_max_transaction_buffers;
1275        if (journal->j_committing_transaction)
1276                nblocks += atomic_read(&journal->j_committing_transaction->
1277                                       t_outstanding_credits);
1278        return nblocks;
1279}
1280
1281/*
1282 * Definitions which augment the buffer_head layer
1283 */
1284
1285/* journaling buffer types */
1286#define BJ_None         0       /* Not journaled */
1287#define BJ_Metadata     1       /* Normal journaled metadata */
1288#define BJ_Forget       2       /* Buffer superseded by this transaction */
1289#define BJ_IO           3       /* Buffer is for temporary IO use */
1290#define BJ_Shadow       4       /* Buffer contents being shadowed to the log */
1291#define BJ_LogCtl       5       /* Buffer contains log descriptors */
1292#define BJ_Reserved     6       /* Buffer is reserved for access by journal */
1293#define BJ_Types        7
1294
1295extern int jbd_blocks_per_page(struct inode *inode);
1296
1297/* JBD uses a CRC32 checksum */
1298#define JBD_MAX_CHECKSUM_SIZE 4
1299
1300static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
1301                              const void *address, unsigned int length)
1302{
1303        struct {
1304                struct shash_desc shash;
1305                char ctx[JBD_MAX_CHECKSUM_SIZE];
1306        } desc;
1307        int err;
1308
1309        BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >
1310                JBD_MAX_CHECKSUM_SIZE);
1311
1312        desc.shash.tfm = journal->j_chksum_driver;
1313        desc.shash.flags = 0;
1314        *(u32 *)desc.ctx = crc;
1315
1316        err = crypto_shash_update(&desc.shash, address, length);
1317        BUG_ON(err);
1318
1319        return *(u32 *)desc.ctx;
1320}
1321
1322#ifdef __KERNEL__
1323
1324#define buffer_trace_init(bh)   do {} while (0)
1325#define print_buffer_fields(bh) do {} while (0)
1326#define print_buffer_trace(bh)  do {} while (0)
1327#define BUFFER_TRACE(bh, info)  do {} while (0)
1328#define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1329#define JBUFFER_TRACE(jh, info) do {} while (0)
1330
1331#endif  /* __KERNEL__ */
1332
1333#endif  /* _LINUX_JBD2_H */
1334
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