include/linux/jbd.h

   1 /*
   2  * linux/include/linux/jbd.h
   3  *
   4  * Written by Stephen C. Tweedie <sct@redhat.com>
   5  *
   6  * Copyright 1998-2000 Red Hat, Inc --- All Rights Reserved
   7  *
   8  * This file is part of the Linux kernel and is made available under
   9  * the terms of the GNU General Public License, version 2, or at your
  10  * option, any later version, incorporated herein by reference.
  11  *
  12  * Definitions for transaction data structures for the buffer cache
  13  * filesystem journaling support.
  14  */
  15
  16 #ifndef _LINUX_JBD_H
  17 #define _LINUX_JBD_H
  18
  19 /* Allow this file to be included directly into e2fsprogs */
  20 #ifndef __KERNEL__
  21 #include "jfs_compat.h"
  22 #define JFS_DEBUG
  23 #define jfs_debug jbd_debug
  24 #else
  25
  26 #include <linux/types.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/journal-head.h>
  29 #include <linux/stddef.h>
  30 #include <linux/bit_spinlock.h>
  31 #include <linux/mutex.h>
  32 #include <linux/timer.h>
  33 #include <linux/lockdep.h>
  34
  35 #define journal_oom_retry 1
  36
  37 /*
  38  * Define JBD_PARANOID_IOFAIL to cause a kernel BUG() if ext3 finds
  39  * certain classes of error which can occur due to failed IOs.  Under
  40  * normal use we want ext3 to continue after such errors, because
  41  * hardware _can_ fail, but for debugging purposes when running tests on
  42  * known-good hardware we may want to trap these errors.
  43  */
  44 #undef JBD_PARANOID_IOFAIL
  45
  46 /*
  47  * The default maximum commit age, in seconds.
  48  */
  49 #define JBD_DEFAULT_MAX_COMMIT_AGE 5
  50
  51 #ifdef CONFIG_JBD_DEBUG
  52 /*
  53  * Define JBD_EXPENSIVE_CHECKING to enable more expensive internal
  54  * consistency checks.  By default we don't do this unless
  55  * CONFIG_JBD_DEBUG is on.
  56  */
  57 #define JBD_EXPENSIVE_CHECKING
  58 extern u8 journal_enable_debug;
  59
  60 #define jbd_debug(n, f, a...)                                           \
  61         do {                                                            \
  62                 if ((n) <= journal_enable_debug) {                      \
  63                         printk (KERN_DEBUG "(%s, %d): %s: ",            \
  64                                 __FILE__, __LINE__, __func__);  \
  65                         printk (f, ## a);                               \
  66                 }                                                       \
  67         } while (0)
  68 #else
  69 #define jbd_debug(f, a...)      /**/
  70 #endif
  71
  72 static inline void *jbd_alloc(size_t size, gfp_t flags)
  73 {
  74         return (void *)__get_free_pages(flags, get_order(size));
  75 }
  76
  77 static inline void jbd_free(void *ptr, size_t size)
  78 {
  79         free_pages((unsigned long)ptr, get_order(size));
  80 };
  81
  82 #define JFS_MIN_JOURNAL_BLOCKS 1024
  83
  84
  85 /**
  86  * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.
  87  *
  88  * All filesystem modifications made by the process go
  89  * through this handle.  Recursive operations (such as quota operations)
  90  * are gathered into a single update.
  91  *
  92  * The buffer credits field is used to account for journaled buffers
  93  * being modified by the running process.  To ensure that there is
  94  * enough log space for all outstanding operations, we need to limit the
  95  * number of outstanding buffers possible at any time.  When the
  96  * operation completes, any buffer credits not used are credited back to
  97  * the transaction, so that at all times we know how many buffers the
  98  * outstanding updates on a transaction might possibly touch.
  99  *
 100  * This is an opaque datatype.
 101  **/
 102 typedef struct handle_s         handle_t;       /* Atomic operation type */
 103
 104
 105 /**
 106  * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.
 107  *
 108  * journal_t is linked to from the fs superblock structure.
 109  *
 110  * We use the journal_t to keep track of all outstanding transaction
 111  * activity on the filesystem, and to manage the state of the log
 112  * writing process.
 113  *
 114  * This is an opaque datatype.
 115  **/
 116 typedef struct journal_s        journal_t;      /* Journal control structure */
 117 #endif
 118
 119 /*
 120  * Internal structures used by the logging mechanism:
 121  */
 122
 123 #define JFS_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
 124
 125 /*
 126  * On-disk structures
 127  */
 128
 129 /*
 130  * Descriptor block types:
 131  */
 132
 133 #define JFS_DESCRIPTOR_BLOCK    1
 134 #define JFS_COMMIT_BLOCK        2
 135 #define JFS_SUPERBLOCK_V1       3
 136 #define JFS_SUPERBLOCK_V2       4
 137 #define JFS_REVOKE_BLOCK        5
 138
 139 /*
 140  * Standard header for all descriptor blocks:
 141  */
 142 typedef struct journal_header_s
 143 {
 144         __be32          h_magic;
 145         __be32          h_blocktype;
 146         __be32          h_sequence;
 147 } journal_header_t;
 148
 149
 150 /*
 151  * The block tag: used to describe a single buffer in the journal
 152  */
 153 typedef struct journal_block_tag_s
 154 {
 155         __be32          t_blocknr;      /* The on-disk block number */
 156         __be32          t_flags;        /* See below */
 157 } journal_block_tag_t;
 158
 159 /*
 160  * The revoke descriptor: used on disk to describe a series of blocks to
 161  * be revoked from the log
 162  */
 163 typedef struct journal_revoke_header_s
 164 {
 165         journal_header_t r_header;
 166         __be32           r_count;       /* Count of bytes used in the block */
 167 } journal_revoke_header_t;
 168
 169
 170 /* Definitions for the journal tag flags word: */
 171 #define JFS_FLAG_ESCAPE         1       /* on-disk block is escaped */
 172 #define JFS_FLAG_SAME_UUID      2       /* block has same uuid as previous */
 173 #define JFS_FLAG_DELETED        4       /* block deleted by this transaction */
 174 #define JFS_FLAG_LAST_TAG       8       /* last tag in this descriptor block */
 175
 176
 177 /*
 178  * The journal superblock.  All fields are in big-endian byte order.
 179  */
 180 typedef struct journal_superblock_s
 181 {
 182 /* 0x0000 */
 183         journal_header_t s_header;
 184
 185 /* 0x000C */
 186         /* Static information describing the journal */
 187         __be32  s_blocksize;            /* journal device blocksize */
 188         __be32  s_maxlen;               /* total blocks in journal file */
 189         __be32  s_first;                /* first block of log information */
 190
 191 /* 0x0018 */
 192         /* Dynamic information describing the current state of the log */
 193         __be32  s_sequence;             /* first commit ID expected in log */
 194         __be32  s_start;                /* blocknr of start of log */
 195
 196 /* 0x0020 */
 197         /* Error value, as set by journal_abort(). */
 198         __be32  s_errno;
 199
 200 /* 0x0024 */
 201         /* Remaining fields are only valid in a version-2 superblock */
 202         __be32  s_feature_compat;       /* compatible feature set */
 203         __be32  s_feature_incompat;     /* incompatible feature set */
 204         __be32  s_feature_ro_compat;    /* readonly-compatible feature set */
 205 /* 0x0030 */
 206         __u8    s_uuid[16];             /* 128-bit uuid for journal */
 207
 208 /* 0x0040 */
 209         __be32  s_nr_users;             /* Nr of filesystems sharing log */
 210
 211         __be32  s_dynsuper;             /* Blocknr of dynamic superblock copy*/
 212
 213 /* 0x0048 */
 214         __be32  s_max_transaction;      /* Limit of journal blocks per trans.*/
 215         __be32  s_max_trans_data;       /* Limit of data blocks per trans. */
 216
 217 /* 0x0050 */
 218         __u32   s_padding[44];
 219
 220 /* 0x0100 */
 221         __u8    s_users[16*48];         /* ids of all fs'es sharing the log */
 222 /* 0x0400 */
 223 } journal_superblock_t;
 224
 225 #define JFS_HAS_COMPAT_FEATURE(j,mask)                                  \
 226         ((j)->j_format_version >= 2 &&                                  \
 227          ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
 228 #define JFS_HAS_RO_COMPAT_FEATURE(j,mask)                               \
 229         ((j)->j_format_version >= 2 &&                                  \
 230          ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
 231 #define JFS_HAS_INCOMPAT_FEATURE(j,mask)                                \
 232         ((j)->j_format_version >= 2 &&                                  \
 233          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
 234
 235 #define JFS_FEATURE_INCOMPAT_REVOKE     0x00000001
 236
 237 /* Features known to this kernel version: */
 238 #define JFS_KNOWN_COMPAT_FEATURES       0
 239 #define JFS_KNOWN_ROCOMPAT_FEATURES     0
 240 #define JFS_KNOWN_INCOMPAT_FEATURES     JFS_FEATURE_INCOMPAT_REVOKE
 241
 242 #ifdef __KERNEL__
 243
 244 #include <linux/fs.h>
 245 #include <linux/sched.h>
 246
 247 #define J_ASSERT(assert)        BUG_ON(!(assert))
 248
 249 #define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
 250 #define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
 251
 252 #if defined(JBD_PARANOID_IOFAIL)
 253 #define J_EXPECT(expr, why...)          J_ASSERT(expr)
 254 #define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
 255 #define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
 256 #else
 257 #define __journal_expect(expr, why...)                                       \
 258         ({                                                                   \
 259                 int val = (expr);                                            \
 260                 if (!val) {                                                  \
 261                         printk(KERN_ERR                                      \
 262                                 "EXT3-fs unexpected failure: %s;\n",# expr); \
 263                         printk(KERN_ERR why "\n");                           \
 264                 }                                                            \
 265                 val;                                                         \
 266         })
 267 #define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)
 268 #define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)
 269 #define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)
 270 #endif
 271
 272 enum jbd_state_bits {
 273         BH_JBD                  /* Has an attached ext3 journal_head */
 274           = BH_PrivateStart,
 275         BH_JWrite,              /* Being written to log (@@@ DEBUGGING) */
 276         BH_Freed,               /* Has been freed (truncated) */
 277         BH_Revoked,             /* Has been revoked from the log */
 278         BH_RevokeValid,         /* Revoked flag is valid */
 279         BH_JBDDirty,            /* Is dirty but journaled */
 280         BH_State,               /* Pins most journal_head state */
 281         BH_JournalHead,         /* Pins bh->b_private and jh->b_bh */
 282         BH_Unshadow,            /* Dummy bit, for BJ_Shadow wakeup filtering */
 283 };
 284
 285 BUFFER_FNS(JBD, jbd)
 286 BUFFER_FNS(JWrite, jwrite)
 287 BUFFER_FNS(JBDDirty, jbddirty)
 288 TAS_BUFFER_FNS(JBDDirty, jbddirty)
 289 BUFFER_FNS(Revoked, revoked)
 290 TAS_BUFFER_FNS(Revoked, revoked)
 291 BUFFER_FNS(RevokeValid, revokevalid)
 292 TAS_BUFFER_FNS(RevokeValid, revokevalid)
 293 BUFFER_FNS(Freed, freed)
 294
 295 static inline struct buffer_head *jh2bh(struct journal_head *jh)
 296 {
 297         return jh->b_bh;
 298 }
 299
 300 static inline struct journal_head *bh2jh(struct buffer_head *bh)
 301 {
 302         return bh->b_private;
 303 }
 304
 305 static inline void jbd_lock_bh_state(struct buffer_head *bh)
 306 {
 307         bit_spin_lock(BH_State, &bh->b_state);
 308 }
 309
 310 static inline int jbd_trylock_bh_state(struct buffer_head *bh)
 311 {
 312         return bit_spin_trylock(BH_State, &bh->b_state);
 313 }
 314
 315 static inline int jbd_is_locked_bh_state(struct buffer_head *bh)
 316 {
 317         return bit_spin_is_locked(BH_State, &bh->b_state);
 318 }
 319
 320 static inline void jbd_unlock_bh_state(struct buffer_head *bh)
 321 {
 322         bit_spin_unlock(BH_State, &bh->b_state);
 323 }
 324
 325 static inline void jbd_lock_bh_journal_head(struct buffer_head *bh)
 326 {
 327         bit_spin_lock(BH_JournalHead, &bh->b_state);
 328 }
 329
 330 static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh)
 331 {
 332         bit_spin_unlock(BH_JournalHead, &bh->b_state);
 333 }
 334
 335 struct jbd_revoke_table_s;
 336
 337 /**
 338  * struct handle_s - this is the concrete type associated with handle_t.
 339  * @h_transaction: Which compound transaction is this update a part of?
 340  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
 341  * @h_ref: Reference count on this handle
 342  * @h_err: Field for caller's use to track errors through large fs operations
 343  * @h_sync: flag for sync-on-close
 344  * @h_jdata: flag to force data journaling
 345  * @h_aborted: flag indicating fatal error on handle
 346  * @h_lockdep_map: lockdep info for debugging lock problems
 347  */
 348 struct handle_s
 349 {
 350         /* Which compound transaction is this update a part of? */
 351         transaction_t           *h_transaction;
 352
 353         /* Number of remaining buffers we are allowed to dirty: */
 354         int                     h_buffer_credits;
 355
 356         /* Reference count on this handle */
 357         int                     h_ref;
 358
 359         /* Field for caller's use to track errors through large fs */
 360         /* operations */
 361         int                     h_err;
 362
 363         /* Flags [no locking] */
 364         unsigned int    h_sync:         1;      /* sync-on-close */
 365         unsigned int    h_jdata:        1;      /* force data journaling */
 366         unsigned int    h_aborted:      1;      /* fatal error on handle */
 367
 368 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 369         struct lockdep_map      h_lockdep_map;
 370 #endif
 371 };
 372
 373
 374 /* The transaction_t type is the guts of the journaling mechanism.  It
 375  * tracks a compound transaction through its various states:
 376  *
 377  * RUNNING:     accepting new updates
 378  * LOCKED:      Updates still running but we don't accept new ones
 379  * RUNDOWN:     Updates are tidying up but have finished requesting
 380  *              new buffers to modify (state not used for now)
 381  * FLUSH:       All updates complete, but we are still writing to disk
 382  * COMMIT:      All data on disk, writing commit record
 383  * FINISHED:    We still have to keep the transaction for checkpointing.
 384  *
 385  * The transaction keeps track of all of the buffers modified by a
 386  * running transaction, and all of the buffers committed but not yet
 387  * flushed to home for finished transactions.
 388  */
 389
 390 /*
 391  * Lock ranking:
 392  *
 393  *    j_list_lock
 394  *      ->jbd_lock_bh_journal_head()    (This is "innermost")
 395  *
 396  *    j_state_lock
 397  *    ->jbd_lock_bh_state()
 398  *
 399  *    jbd_lock_bh_state()
 400  *    ->j_list_lock
 401  *
 402  *    j_state_lock
 403  *    ->t_handle_lock
 404  *
 405  *    j_state_lock
 406  *    ->j_list_lock                     (journal_unmap_buffer)
 407  *
 408  */
 409
 410 struct transaction_s
 411 {
 412         /* Pointer to the journal for this transaction. [no locking] */
 413         journal_t               *t_journal;
 414
 415         /* Sequence number for this transaction [no locking] */
 416         tid_t                   t_tid;
 417
 418         /*
 419          * Transaction's current state
 420          * [no locking - only kjournald alters this]
 421          * [j_list_lock] guards transition of a transaction into T_FINISHED
 422          * state and subsequent call of __journal_drop_transaction()
 423          * FIXME: needs barriers
 424          * KLUDGE: [use j_state_lock]
 425          */
 426         enum {
 427                 T_RUNNING,
 428                 T_LOCKED,
 429                 T_RUNDOWN,
 430                 T_FLUSH,
 431                 T_COMMIT,
 432                 T_FINISHED
 433         }                       t_state;
 434
 435         /*
 436          * Where in the log does this transaction's commit start? [no locking]
 437          */
 438         unsigned int            t_log_start;
 439
 440         /* Number of buffers on the t_buffers list [j_list_lock] */
 441         int                     t_nr_buffers;
 442
 443         /*
 444          * Doubly-linked circular list of all buffers reserved but not yet
 445          * modified by this transaction [j_list_lock]
 446          */
 447         struct journal_head     *t_reserved_list;
 448
 449         /*
 450          * Doubly-linked circular list of all buffers under writeout during
 451          * commit [j_list_lock]
 452          */
 453         struct journal_head     *t_locked_list;
 454
 455         /*
 456          * Doubly-linked circular list of all metadata buffers owned by this
 457          * transaction [j_list_lock]
 458          */
 459         struct journal_head     *t_buffers;
 460
 461         /*
 462          * Doubly-linked circular list of all data buffers still to be
 463          * flushed before this transaction can be committed [j_list_lock]
 464          */
 465         struct journal_head     *t_sync_datalist;
 466
 467         /*
 468          * Doubly-linked circular list of all forget buffers (superseded
 469          * buffers which we can un-checkpoint once this transaction commits)
 470          * [j_list_lock]
 471          */
 472         struct journal_head     *t_forget;
 473
 474         /*
 475          * Doubly-linked circular list of all buffers still to be flushed before
 476          * this transaction can be checkpointed. [j_list_lock]
 477          */
 478         struct journal_head     *t_checkpoint_list;
 479
 480         /*
 481          * Doubly-linked circular list of all buffers submitted for IO while
 482          * checkpointing. [j_list_lock]
 483          */
 484         struct journal_head     *t_checkpoint_io_list;
 485
 486         /*
 487          * Doubly-linked circular list of temporary buffers currently undergoing
 488          * IO in the log [j_list_lock]
 489          */
 490         struct journal_head     *t_iobuf_list;
 491
 492         /*
 493          * Doubly-linked circular list of metadata buffers being shadowed by log
 494          * IO.  The IO buffers on the iobuf list and the shadow buffers on this
 495          * list match each other one for one at all times. [j_list_lock]
 496          */
 497         struct journal_head     *t_shadow_list;
 498
 499         /*
 500          * Doubly-linked circular list of control buffers being written to the
 501          * log. [j_list_lock]
 502          */
 503         struct journal_head     *t_log_list;
 504
 505         /*
 506          * Protects info related to handles
 507          */
 508         spinlock_t              t_handle_lock;
 509
 510         /*
 511          * Number of outstanding updates running on this transaction
 512          * [t_handle_lock]
 513          */
 514         int                     t_updates;
 515
 516         /*
 517          * Number of buffers reserved for use by all handles in this transaction
 518          * handle but not yet modified. [t_handle_lock]
 519          */
 520         int                     t_outstanding_credits;
 521
 522         /*
 523          * Forward and backward links for the circular list of all transactions
 524          * awaiting checkpoint. [j_list_lock]
 525          */
 526         transaction_t           *t_cpnext, *t_cpprev;
 527
 528         /*
 529          * When will the transaction expire (become due for commit), in jiffies?
 530          * [no locking]
 531          */
 532         unsigned long           t_expires;
 533
 534         /*
 535          * When this transaction started, in nanoseconds [no locking]
 536          */
 537         ktime_t                 t_start_time;
 538
 539         /*
 540          * How many handles used this transaction? [t_handle_lock]
 541          */
 542         int t_handle_count;
 543
 544         /*
 545          * This transaction is being forced and some process is
 546          * waiting for it to finish.
 547          */
 548         unsigned int t_synchronous_commit:1;
 549 };
 550
 551 /**
 552  * struct journal_s - this is the concrete type associated with journal_t.
 553  * @j_flags:  General journaling state flags
 554  * @j_errno:  Is there an outstanding uncleared error on the journal (from a
 555  *     prior abort)?
 556  * @j_sb_buffer: First part of superblock buffer
 557  * @j_superblock: Second part of superblock buffer
 558  * @j_format_version: Version of the superblock format
 559  * @j_state_lock: Protect the various scalars in the journal
 560  * @j_barrier_count:  Number of processes waiting to create a barrier lock
 561  * @j_barrier: The barrier lock itself
 562  * @j_running_transaction: The current running transaction..
 563  * @j_committing_transaction: the transaction we are pushing to disk
 564  * @j_checkpoint_transactions: a linked circular list of all transactions
 565  *  waiting for checkpointing
 566  * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
 567  *  to start committing, or for a barrier lock to be released
 568  * @j_wait_logspace: Wait queue for waiting for checkpointing to complete
 569  * @j_wait_done_commit: Wait queue for waiting for commit to complete
 570  * @j_wait_checkpoint:  Wait queue to trigger checkpointing
 571  * @j_wait_commit: Wait queue to trigger commit
 572  * @j_wait_updates: Wait queue to wait for updates to complete
 573  * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
 574  * @j_head: Journal head - identifies the first unused block in the journal
 575  * @j_tail: Journal tail - identifies the oldest still-used block in the
 576  *  journal.
 577  * @j_free: Journal free - how many free blocks are there in the journal?
 578  * @j_first: The block number of the first usable block
 579  * @j_last: The block number one beyond the last usable block
 580  * @j_dev: Device where we store the journal
 581  * @j_blocksize: blocksize for the location where we store the journal.
 582  * @j_blk_offset: starting block offset for into the device where we store the
 583  *     journal
 584  * @j_fs_dev: Device which holds the client fs.  For internal journal this will
 585  *     be equal to j_dev
 586  * @j_maxlen: Total maximum capacity of the journal region on disk.
 587  * @j_list_lock: Protects the buffer lists and internal buffer state.
 588  * @j_inode: Optional inode where we store the journal.  If present, all journal
 589  *     block numbers are mapped into this inode via bmap().
 590  * @j_tail_sequence:  Sequence number of the oldest transaction in the log
 591  * @j_transaction_sequence: Sequence number of the next transaction to grant
 592  * @j_commit_sequence: Sequence number of the most recently committed
 593  *  transaction
 594  * @j_commit_request: Sequence number of the most recent transaction wanting
 595  *     commit
 596  * @j_uuid: Uuid of client object.
 597  * @j_task: Pointer to the current commit thread for this journal
 598  * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
 599  *     single compound commit transaction
 600  * @j_commit_interval: What is the maximum transaction lifetime before we begin
 601  *  a commit?
 602  * @j_commit_timer:  The timer used to wakeup the commit thread
 603  * @j_revoke_lock: Protect the revoke table
 604  * @j_revoke: The revoke table - maintains the list of revoked blocks in the
 605  *     current transaction.
 606  * @j_revoke_table: alternate revoke tables for j_revoke
 607  * @j_wbuf: array of buffer_heads for journal_commit_transaction
 608  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
 609  *      number that will fit in j_blocksize
 610  * @j_last_sync_writer: most recent pid which did a synchronous write
 611  * @j_average_commit_time: the average amount of time in nanoseconds it
 612  *      takes to commit a transaction to the disk.
 613  * @j_private: An opaque pointer to fs-private information.
 614  */
 615
 616 struct journal_s
 617 {
 618         /* General journaling state flags [j_state_lock] */
 619         unsigned long           j_flags;
 620
 621         /*
 622          * Is there an outstanding uncleared error on the journal (from a prior
 623          * abort)? [j_state_lock]
 624          */
 625         int                     j_errno;
 626
 627         /* The superblock buffer */
 628         struct buffer_head      *j_sb_buffer;
 629         journal_superblock_t    *j_superblock;
 630
 631         /* Version of the superblock format */
 632         int                     j_format_version;
 633
 634         /*
 635          * Protect the various scalars in the journal
 636          */
 637         spinlock_t              j_state_lock;
 638
 639         /*
 640          * Number of processes waiting to create a barrier lock [j_state_lock]
 641          */
 642         int                     j_barrier_count;
 643
 644         /* The barrier lock itself */
 645         struct mutex            j_barrier;
 646
 647         /*
 648          * Transactions: The current running transaction...
 649          * [j_state_lock] [caller holding open handle]
 650          */
 651         transaction_t           *j_running_transaction;
 652
 653         /*
 654          * the transaction we are pushing to disk
 655          * [j_state_lock] [caller holding open handle]
 656          */
 657         transaction_t           *j_committing_transaction;
 658
 659         /*
 660          * ... and a linked circular list of all transactions waiting for
 661          * checkpointing. [j_list_lock]
 662          */
 663         transaction_t           *j_checkpoint_transactions;
 664
 665         /*
 666          * Wait queue for waiting for a locked transaction to start committing,
 667          * or for a barrier lock to be released
 668          */
 669         wait_queue_head_t       j_wait_transaction_locked;
 670
 671         /* Wait queue for waiting for checkpointing to complete */
 672         wait_queue_head_t       j_wait_logspace;
 673
 674         /* Wait queue for waiting for commit to complete */
 675         wait_queue_head_t       j_wait_done_commit;
 676
 677         /* Wait queue to trigger checkpointing */
 678         wait_queue_head_t       j_wait_checkpoint;
 679
 680         /* Wait queue to trigger commit */
 681         wait_queue_head_t       j_wait_commit;
 682
 683         /* Wait queue to wait for updates to complete */
 684         wait_queue_head_t       j_wait_updates;
 685
 686         /* Semaphore for locking against concurrent checkpoints */
 687         struct mutex            j_checkpoint_mutex;
 688
 689         /*
 690          * Journal head: identifies the first unused block in the journal.
 691          * [j_state_lock]
 692          */
 693         unsigned int            j_head;
 694
 695         /*
 696          * Journal tail: identifies the oldest still-used block in the journal.
 697          * [j_state_lock]
 698          */
 699         unsigned int            j_tail;
 700
 701         /*
 702          * Journal free: how many free blocks are there in the journal?
 703          * [j_state_lock]
 704          */
 705         unsigned int            j_free;
 706
 707         /*
 708          * Journal start and end: the block numbers of the first usable block
 709          * and one beyond the last usable block in the journal. [j_state_lock]
 710          */
 711         unsigned int            j_first;
 712         unsigned int            j_last;
 713
 714         /*
 715          * Device, blocksize and starting block offset for the location where we
 716          * store the journal.
 717          */
 718         struct block_device     *j_dev;
 719         int                     j_blocksize;
 720         unsigned int            j_blk_offset;
 721
 722         /*
 723          * Device which holds the client fs.  For internal journal this will be
 724          * equal to j_dev.
 725          */
 726         struct block_device     *j_fs_dev;
 727
 728         /* Total maximum capacity of the journal region on disk. */
 729         unsigned int            j_maxlen;
 730
 731         /*
 732          * Protects the buffer lists and internal buffer state.
 733          */
 734         spinlock_t              j_list_lock;
 735
 736         /* Optional inode where we store the journal.  If present, all */
 737         /* journal block numbers are mapped into this inode via */
 738         /* bmap(). */
 739         struct inode            *j_inode;
 740
 741         /*
 742          * Sequence number of the oldest transaction in the log [j_state_lock]
 743          */
 744         tid_t                   j_tail_sequence;
 745
 746         /*
 747          * Sequence number of the next transaction to grant [j_state_lock]
 748          */
 749         tid_t                   j_transaction_sequence;
 750
 751         /*
 752          * Sequence number of the most recently committed transaction
 753          * [j_state_lock].
 754          */
 755         tid_t                   j_commit_sequence;
 756
 757         /*
 758          * Sequence number of the most recent transaction wanting commit
 759          * [j_state_lock]
 760          */
 761         tid_t                   j_commit_request;
 762
 763         /*
 764          * Journal uuid: identifies the object (filesystem, LVM volume etc)
 765          * backed by this journal.  This will eventually be replaced by an array
 766          * of uuids, allowing us to index multiple devices within a single
 767          * journal and to perform atomic updates across them.
 768          */
 769         __u8                    j_uuid[16];
 770
 771         /* Pointer to the current commit thread for this journal */
 772         struct task_struct      *j_task;
 773
 774         /*
 775          * Maximum number of metadata buffers to allow in a single compound
 776          * commit transaction
 777          */
 778         int                     j_max_transaction_buffers;
 779
 780         /*
 781          * What is the maximum transaction lifetime before we begin a commit?
 782          */
 783         unsigned long           j_commit_interval;
 784
 785         /* The timer used to wakeup the commit thread: */
 786         struct timer_list       j_commit_timer;
 787
 788         /*
 789          * The revoke table: maintains the list of revoked blocks in the
 790          * current transaction.  [j_revoke_lock]
 791          */
 792         spinlock_t              j_revoke_lock;
 793         struct jbd_revoke_table_s *j_revoke;
 794         struct jbd_revoke_table_s *j_revoke_table[2];
 795
 796         /*
 797          * array of bhs for journal_commit_transaction
 798          */
 799         struct buffer_head      **j_wbuf;
 800         int                     j_wbufsize;
 801
 802         /*
 803          * this is the pid of the last person to run a synchronous operation
 804          * through the journal.
 805          */
 806         pid_t                   j_last_sync_writer;
 807
 808         /*
 809          * the average amount of time in nanoseconds it takes to commit a
 810          * transaction to the disk.  [j_state_lock]
 811          */
 812         u64                     j_average_commit_time;
 813
 814         /*
 815          * An opaque pointer to fs-private information.  ext3 puts its
 816          * superblock pointer here
 817          */
 818         void *j_private;
 819 };
 820
 821 /*
 822  * Journal flag definitions
 823  */
 824 #define JFS_UNMOUNT     0x001   /* Journal thread is being destroyed */
 825 #define JFS_ABORT       0x002   /* Journaling has been aborted for errors. */
 826 #define JFS_ACK_ERR     0x004   /* The errno in the sb has been acked */
 827 #define JFS_FLUSHED     0x008   /* The journal superblock has been flushed */
 828 #define JFS_LOADED      0x010   /* The journal superblock has been loaded */
 829 #define JFS_BARRIER     0x020   /* Use IDE barriers */
 830 #define JFS_ABORT_ON_SYNCDATA_ERR       0x040  /* Abort the journal on file
 831                                                 * data write error in ordered
 832                                                 * mode */
 833
 834 /*
 835  * Function declarations for the journaling transaction and buffer
 836  * management
 837  */
 838
 839 /* Filing buffers */
 840 extern void journal_unfile_buffer(journal_t *, struct journal_head *);
 841 extern void __journal_unfile_buffer(struct journal_head *);
 842 extern void __journal_refile_buffer(struct journal_head *);
 843 extern void journal_refile_buffer(journal_t *, struct journal_head *);
 844 extern void __journal_file_buffer(struct journal_head *, transaction_t *, int);
 845 extern void __journal_free_buffer(struct journal_head *bh);
 846 extern void journal_file_buffer(struct journal_head *, transaction_t *, int);
 847 extern void __journal_clean_data_list(transaction_t *transaction);
 848
 849 /* Log buffer allocation */
 850 extern struct journal_head * journal_get_descriptor_buffer(journal_t *);
 851 int journal_next_log_block(journal_t *, unsigned int *);
 852
 853 /* Commit management */
 854 extern void journal_commit_transaction(journal_t *);
 855
 856 /* Checkpoint list management */
 857 int __journal_clean_checkpoint_list(journal_t *journal);
 858 int __journal_remove_checkpoint(struct journal_head *);
 859 void __journal_insert_checkpoint(struct journal_head *, transaction_t *);
 860
 861 /* Buffer IO */
 862 extern int
 863 journal_write_metadata_buffer(transaction_t       *transaction,
 864                               struct journal_head  *jh_in,
 865                               struct journal_head **jh_out,
 866                               unsigned int blocknr);
 867
 868 /* Transaction locking */
 869 extern void             __wait_on_journal (journal_t *);
 870
 871 /*
 872  * Journal locking.
 873  *
 874  * We need to lock the journal during transaction state changes so that nobody
 875  * ever tries to take a handle on the running transaction while we are in the
 876  * middle of moving it to the commit phase.  j_state_lock does this.
 877  *
 878  * Note that the locking is completely interrupt unsafe.  We never touch
 879  * journal structures from interrupts.
 880  */
 881
 882 static inline handle_t *journal_current_handle(void)
 883 {
 884         return current->journal_info;
 885 }
 886
 887 /* The journaling code user interface:
 888  *
 889  * Create and destroy handles
 890  * Register buffer modifications against the current transaction.
 891  */
 892
 893 extern handle_t *journal_start(journal_t *, int nblocks);
 894 extern int       journal_restart (handle_t *, int nblocks);
 895 extern int       journal_extend (handle_t *, int nblocks);
 896 extern int       journal_get_write_access(handle_t *, struct buffer_head *);
 897 extern int       journal_get_create_access (handle_t *, struct buffer_head *);
 898 extern int       journal_get_undo_access(handle_t *, struct buffer_head *);
 899 extern int       journal_dirty_data (handle_t *, struct buffer_head *);
 900 extern int       journal_dirty_metadata (handle_t *, struct buffer_head *);
 901 extern void      journal_release_buffer (handle_t *, struct buffer_head *);
 902 extern int       journal_forget (handle_t *, struct buffer_head *);
 903 extern void      journal_sync_buffer (struct buffer_head *);
 904 extern void      journal_invalidatepage(journal_t *,
 905                                 struct page *, unsigned long);
 906 extern int       journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
 907 extern int       journal_stop(handle_t *);
 908 extern int       journal_flush (journal_t *);
 909 extern void      journal_lock_updates (journal_t *);
 910 extern void      journal_unlock_updates (journal_t *);
 911
 912 extern journal_t * journal_init_dev(struct block_device *bdev,
 913                                 struct block_device *fs_dev,
 914                                 int start, int len, int bsize);
 915 extern journal_t * journal_init_inode (struct inode *);
 916 extern int         journal_update_format (journal_t *);
 917 extern int         journal_check_used_features
 918                    (journal_t *, unsigned long, unsigned long, unsigned long);
 919 extern int         journal_check_available_features
 920                    (journal_t *, unsigned long, unsigned long, unsigned long);
 921 extern int         journal_set_features
 922                    (journal_t *, unsigned long, unsigned long, unsigned long);
 923 extern int         journal_create     (journal_t *);
 924 extern int         journal_load       (journal_t *journal);
 925 extern int         journal_destroy    (journal_t *);
 926 extern int         journal_recover    (journal_t *journal);
 927 extern int         journal_wipe       (journal_t *, int);
 928 extern int         journal_skip_recovery        (journal_t *);
 929 extern void        journal_update_superblock    (journal_t *, int);
 930 extern void        journal_abort      (journal_t *, int);
 931 extern int         journal_errno      (journal_t *);
 932 extern void        journal_ack_err    (journal_t *);
 933 extern int         journal_clear_err  (journal_t *);
 934 extern int         journal_bmap(journal_t *, unsigned int, unsigned int *);
 935 extern int         journal_force_commit(journal_t *);
 936
 937 /*
 938  * journal_head management
 939  */
 940 struct journal_head *journal_add_journal_head(struct buffer_head *bh);
 941 struct journal_head *journal_grab_journal_head(struct buffer_head *bh);
 942 void journal_remove_journal_head(struct buffer_head *bh);
 943 void journal_put_journal_head(struct journal_head *jh);
 944
 945 /*
 946  * handle management
 947  */
 948 extern struct kmem_cache *jbd_handle_cache;
 949
 950 static inline handle_t *jbd_alloc_handle(gfp_t gfp_flags)
 951 {
 952         return kmem_cache_alloc(jbd_handle_cache, gfp_flags);
 953 }
 954
 955 static inline void jbd_free_handle(handle_t *handle)
 956 {
 957         kmem_cache_free(jbd_handle_cache, handle);
 958 }
 959
 960 /* Primary revoke support */
 961 #define JOURNAL_REVOKE_DEFAULT_HASH 256
 962 extern int         journal_init_revoke(journal_t *, int);
 963 extern void        journal_destroy_revoke_caches(void);
 964 extern int         journal_init_revoke_caches(void);
 965
 966 extern void        journal_destroy_revoke(journal_t *);
 967 extern int         journal_revoke (handle_t *,
 968                                 unsigned int, struct buffer_head *);
 969 extern int         journal_cancel_revoke(handle_t *, struct journal_head *);
 970 extern void        journal_write_revoke_records(journal_t *,
 971                                                 transaction_t *, int);
 972
 973 /* Recovery revoke support */
 974 extern int      journal_set_revoke(journal_t *, unsigned int, tid_t);
 975 extern int      journal_test_revoke(journal_t *, unsigned int, tid_t);
 976 extern void     journal_clear_revoke(journal_t *);
 977 extern void     journal_switch_revoke_table(journal_t *journal);
 978
 979 /*
 980  * The log thread user interface:
 981  *
 982  * Request space in the current transaction, and force transaction commit
 983  * transitions on demand.
 984  */
 985
 986 int __log_space_left(journal_t *); /* Called with journal locked */
 987 int log_start_commit(journal_t *journal, tid_t tid);
 988 int __log_start_commit(journal_t *journal, tid_t tid);
 989 int journal_start_commit(journal_t *journal, tid_t *tid);
 990 int journal_force_commit_nested(journal_t *journal);
 991 int log_wait_commit(journal_t *journal, tid_t tid);
 992 int log_do_checkpoint(journal_t *journal);
 993
 994 void __log_wait_for_space(journal_t *journal);
 995 extern void     __journal_drop_transaction(journal_t *, transaction_t *);
 996 extern int      cleanup_journal_tail(journal_t *);
 997
 998 /* Debugging code only: */
 999
1000 #define jbd_ENOSYS() \
1001 do {                                                                       \
1002         printk (KERN_ERR "JBD unimplemented function %s\n", __func__); \
1003         current->state = TASK_UNINTERRUPTIBLE;                             \
1004         schedule();                                                        \
1005 } while (1)
1006
1007 /*
1008  * is_journal_abort
1009  *
1010  * Simple test wrapper function to test the JFS_ABORT state flag.  This
1011  * bit, when set, indicates that we have had a fatal error somewhere,
1012  * either inside the journaling layer or indicated to us by the client
1013  * (eg. ext3), and that we and should not commit any further
1014  * transactions.
1015  */
1016
1017 static inline int is_journal_aborted(journal_t *journal)
1018 {
1019         return journal->j_flags & JFS_ABORT;
1020 }
1021
1022 static inline int is_handle_aborted(handle_t *handle)
1023 {
1024         if (handle->h_aborted)
1025                 return 1;
1026         return is_journal_aborted(handle->h_transaction->t_journal);
1027 }
1028
1029 static inline void journal_abort_handle(handle_t *handle)
1030 {
1031         handle->h_aborted = 1;
1032 }
1033
1034 #endif /* __KERNEL__   */
1035
1036 /* Comparison functions for transaction IDs: perform comparisons using
1037  * modulo arithmetic so that they work over sequence number wraps. */
1038
1039 static inline int tid_gt(tid_t x, tid_t y)
1040 {
1041         int difference = (x - y);
1042         return (difference > 0);
1043 }
1044
1045 static inline int tid_geq(tid_t x, tid_t y)
1046 {
1047         int difference = (x - y);
1048         return (difference >= 0);
1049 }
1050
1051 extern int journal_blocks_per_page(struct inode *inode);
1052
1053 /*
1054  * Return the minimum number of blocks which must be free in the journal
1055  * before a new transaction may be started.  Must be called under j_state_lock.
1056  */
1057 static inline int jbd_space_needed(journal_t *journal)
1058 {
1059         int nblocks = journal->j_max_transaction_buffers;
1060         if (journal->j_committing_transaction)
1061                 nblocks += journal->j_committing_transaction->
1062                                         t_outstanding_credits;
1063         return nblocks;
1064 }
1065
1066 /*
1067  * Definitions which augment the buffer_head layer
1068  */
1069
1070 /* journaling buffer types */
1071 #define BJ_None         0       /* Not journaled */
1072 #define BJ_SyncData     1       /* Normal data: flush before commit */
1073 #define BJ_Metadata     2       /* Normal journaled metadata */
1074 #define BJ_Forget       3       /* Buffer superseded by this transaction */
1075 #define BJ_IO           4       /* Buffer is for temporary IO use */
1076 #define BJ_Shadow       5       /* Buffer contents being shadowed to the log */
1077 #define BJ_LogCtl       6       /* Buffer contains log descriptors */
1078 #define BJ_Reserved     7       /* Buffer is reserved for access by journal */
1079 #define BJ_Locked       8       /* Locked for I/O during commit */
1080 #define BJ_Types        9
1081
1082 extern int jbd_blocks_per_page(struct inode *inode);
1083
1084 #ifdef __KERNEL__
1085
1086 #define buffer_trace_init(bh)   do {} while (0)
1087 #define print_buffer_fields(bh) do {} while (0)
1088 #define print_buffer_trace(bh)  do {} while (0)
1089 #define BUFFER_TRACE(bh, info)  do {} while (0)
1090 #define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1091 #define JBUFFER_TRACE(jh, info) do {} while (0)
1092
1093 #endif  /* __KERNEL__ */
1094
1095 #endif  /* _LINUX_JBD_H */