include/linux/jbd2.h

   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_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 JBD2_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
  34 #include <asm/semaphore.h>
  35 #endif
  36
  37 #define journal_oom_retry 1
  38
  39 /*
  40  * Define JBD_PARANIOD_IOFAIL to cause a kernel BUG() if ext3 finds
  41  * certain classes of error which can occur due to failed IOs.  Under
  42  * normal use we want ext3 to continue after such errors, because
  43  * hardware _can_ fail, but for debugging purposes when running tests on
  44  * known-good hardware we may want to trap these errors.
  45  */
  46 #undef JBD_PARANOID_IOFAIL
  47
  48 /*
  49  * The default maximum commit age, in seconds.
  50  */
  51 #define JBD_DEFAULT_MAX_COMMIT_AGE 5
  52
  53 #ifdef CONFIG_JBD_DEBUG
  54 /*
  55  * Define JBD_EXPENSIVE_CHECKING to enable more expensive internal
  56  * consistency checks.  By default we don't do this unless
  57  * CONFIG_JBD_DEBUG is on.
  58  */
  59 #define JBD_EXPENSIVE_CHECKING
  60 extern int jbd2_journal_enable_debug;
  61
  62 #define jbd_debug(n, f, a...)                                           \
  63         do {                                                            \
  64                 if ((n) <= jbd2_journal_enable_debug) {                 \
  65                         printk (KERN_DEBUG "(%s, %d): %s: ",            \
  66                                 __FILE__, __LINE__, __FUNCTION__);      \
  67                         printk (f, ## a);                               \
  68                 }                                                       \
  69         } while (0)
  70 #else
  71 #define jbd_debug(f, a...)      /**/
  72 #endif
  73
  74 extern void * __jbd2_kmalloc (const char *where, size_t size, gfp_t flags, int retry);
  75 extern void * jbd2_slab_alloc(size_t size, gfp_t flags);
  76 extern void jbd2_slab_free(void *ptr, size_t size);
  77
  78 #define jbd_kmalloc(size, flags) \
  79         __jbd2_kmalloc(__FUNCTION__, (size), (flags), journal_oom_retry)
  80 #define jbd_rep_kmalloc(size, flags) \
  81         __jbd2_kmalloc(__FUNCTION__, (size), (flags), 1)
  82
  83 #define JBD2_MIN_JOURNAL_BLOCKS 1024
  84
  85 #ifdef __KERNEL__
  86
  87 /**
  88  * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.
  89  *
  90  * All filesystem modifications made by the process go
  91  * through this handle.  Recursive operations (such as quota operations)
  92  * are gathered into a single update.
  93  *
  94  * The buffer credits field is used to account for journaled buffers
  95  * being modified by the running process.  To ensure that there is
  96  * enough log space for all outstanding operations, we need to limit the
  97  * number of outstanding buffers possible at any time.  When the
  98  * operation completes, any buffer credits not used are credited back to
  99  * the transaction, so that at all times we know how many buffers the
 100  * outstanding updates on a transaction might possibly touch.
 101  *
 102  * This is an opaque datatype.
 103  **/
 104 typedef struct handle_s         handle_t;       /* Atomic operation type */
 105
 106
 107 /**
 108  * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.
 109  *
 110  * journal_t is linked to from the fs superblock structure.
 111  *
 112  * We use the journal_t to keep track of all outstanding transaction
 113  * activity on the filesystem, and to manage the state of the log
 114  * writing process.
 115  *
 116  * This is an opaque datatype.
 117  **/
 118 typedef struct journal_s        journal_t;      /* Journal control structure */
 119 #endif
 120
 121 /*
 122  * Internal structures used by the logging mechanism:
 123  */
 124
 125 #define JBD2_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
 126
 127 /*
 128  * On-disk structures
 129  */
 130
 131 /*
 132  * Descriptor block types:
 133  */
 134
 135 #define JBD2_DESCRIPTOR_BLOCK   1
 136 #define JBD2_COMMIT_BLOCK       2
 137 #define JBD2_SUPERBLOCK_V1      3
 138 #define JBD2_SUPERBLOCK_V2      4
 139 #define JBD2_REVOKE_BLOCK       5
 140
 141 /*
 142  * Standard header for all descriptor blocks:
 143  */
 144 typedef struct journal_header_s
 145 {
 146         __be32          h_magic;
 147         __be32          h_blocktype;
 148         __be32          h_sequence;
 149 } journal_header_t;
 150
 151
 152 /*
 153  * The block tag: used to describe a single buffer in the journal.
 154  * t_blocknr_high is only used if INCOMPAT_64BIT is set, so this
 155  * raw struct shouldn't be used for pointer math or sizeof() - use
 156  * journal_tag_bytes(journal) instead to compute this.
 157  */
 158 typedef struct journal_block_tag_s
 159 {
 160         __be32          t_blocknr;      /* The on-disk block number */
 161         __be32          t_flags;        /* See below */
 162         __be32          t_blocknr_high; /* most-significant high 32bits. */
 163 } journal_block_tag_t;
 164
 165 #define JBD_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))
 166 #define JBD_TAG_SIZE64 (sizeof(journal_block_tag_t))
 167
 168 /*
 169  * The revoke descriptor: used on disk to describe a series of blocks to
 170  * be revoked from the log
 171  */
 172 typedef struct jbd2_journal_revoke_header_s
 173 {
 174         journal_header_t r_header;
 175         __be32           r_count;       /* Count of bytes used in the block */
 176 } jbd2_journal_revoke_header_t;
 177
 178
 179 /* Definitions for the journal tag flags word: */
 180 #define JBD2_FLAG_ESCAPE                1       /* on-disk block is escaped */
 181 #define JBD2_FLAG_SAME_UUID     2       /* block has same uuid as previous */
 182 #define JBD2_FLAG_DELETED       4       /* block deleted by this transaction */
 183 #define JBD2_FLAG_LAST_TAG      8       /* last tag in this descriptor block */
 184
 185
 186 /*
 187  * The journal superblock.  All fields are in big-endian byte order.
 188  */
 189 typedef struct journal_superblock_s
 190 {
 191 /* 0x0000 */
 192         journal_header_t s_header;
 193
 194 /* 0x000C */
 195         /* Static information describing the journal */
 196         __be32  s_blocksize;            /* journal device blocksize */
 197         __be32  s_maxlen;               /* total blocks in journal file */
 198         __be32  s_first;                /* first block of log information */
 199
 200 /* 0x0018 */
 201         /* Dynamic information describing the current state of the log */
 202         __be32  s_sequence;             /* first commit ID expected in log */
 203         __be32  s_start;                /* blocknr of start of log */
 204
 205 /* 0x0020 */
 206         /* Error value, as set by jbd2_journal_abort(). */
 207         __be32  s_errno;
 208
 209 /* 0x0024 */
 210         /* Remaining fields are only valid in a version-2 superblock */
 211         __be32  s_feature_compat;       /* compatible feature set */
 212         __be32  s_feature_incompat;     /* incompatible feature set */
 213         __be32  s_feature_ro_compat;    /* readonly-compatible feature set */
 214 /* 0x0030 */
 215         __u8    s_uuid[16];             /* 128-bit uuid for journal */
 216
 217 /* 0x0040 */
 218         __be32  s_nr_users;             /* Nr of filesystems sharing log */
 219
 220         __be32  s_dynsuper;             /* Blocknr of dynamic superblock copy*/
 221
 222 /* 0x0048 */
 223         __be32  s_max_transaction;      /* Limit of journal blocks per trans.*/
 224         __be32  s_max_trans_data;       /* Limit of data blocks per trans. */
 225
 226 /* 0x0050 */
 227         __u32   s_padding[44];
 228
 229 /* 0x0100 */
 230         __u8    s_users[16*48];         /* ids of all fs'es sharing the log */
 231 /* 0x0400 */
 232 } journal_superblock_t;
 233
 234 #define JBD2_HAS_COMPAT_FEATURE(j,mask)                                 \
 235         ((j)->j_format_version >= 2 &&                                  \
 236          ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
 237 #define JBD2_HAS_RO_COMPAT_FEATURE(j,mask)                              \
 238         ((j)->j_format_version >= 2 &&                                  \
 239          ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
 240 #define JBD2_HAS_INCOMPAT_FEATURE(j,mask)                               \
 241         ((j)->j_format_version >= 2 &&                                  \
 242          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
 243
 244 #define JBD2_FEATURE_INCOMPAT_REVOKE    0x00000001
 245 #define JBD2_FEATURE_INCOMPAT_64BIT     0x00000002
 246
 247 /* Features known to this kernel version: */
 248 #define JBD2_KNOWN_COMPAT_FEATURES      0
 249 #define JBD2_KNOWN_ROCOMPAT_FEATURES    0
 250 #define JBD2_KNOWN_INCOMPAT_FEATURES    (JBD2_FEATURE_INCOMPAT_REVOKE | \
 251                                          JBD2_FEATURE_INCOMPAT_64BIT)
 252
 253 #ifdef __KERNEL__
 254
 255 #include <linux/fs.h>
 256 #include <linux/sched.h>
 257
 258 #define JBD_ASSERTIONS
 259 #ifdef JBD_ASSERTIONS
 260 #define J_ASSERT(assert)                                                \
 261 do {                                                                    \
 262         if (!(assert)) {                                                \
 263                 printk (KERN_EMERG                                      \
 264                         "Assertion failure in %s() at %s:%d: \"%s\"\n", \
 265                         __FUNCTION__, __FILE__, __LINE__, # assert);    \
 266                 BUG();                                                  \
 267         }                                                               \
 268 } while (0)
 269
 270 #if defined(CONFIG_BUFFER_DEBUG)
 271 void buffer_assertion_failure(struct buffer_head *bh);
 272 #define J_ASSERT_BH(bh, expr)                                           \
 273         do {                                                            \
 274                 if (!(expr))                                            \
 275                         buffer_assertion_failure(bh);                   \
 276                 J_ASSERT(expr);                                         \
 277         } while (0)
 278 #define J_ASSERT_JH(jh, expr)   J_ASSERT_BH(jh2bh(jh), expr)
 279 #else
 280 #define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
 281 #define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
 282 #endif
 283
 284 #else
 285 #define J_ASSERT(assert)        do { } while (0)
 286 #endif          /* JBD_ASSERTIONS */
 287
 288 #if defined(JBD_PARANOID_IOFAIL)
 289 #define J_EXPECT(expr, why...)          J_ASSERT(expr)
 290 #define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
 291 #define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
 292 #else
 293 #define __journal_expect(expr, why...)                                       \
 294         ({                                                                   \
 295                 int val = (expr);                                            \
 296                 if (!val) {                                                  \
 297                         printk(KERN_ERR                                      \
 298                                 "EXT3-fs unexpected failure: %s;\n",# expr); \
 299                         printk(KERN_ERR why "\n");                           \
 300                 }                                                            \
 301                 val;                                                         \
 302         })
 303 #define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)
 304 #define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)
 305 #define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)
 306 #endif
 307
 308 enum jbd_state_bits {
 309         BH_JBD                  /* Has an attached ext3 journal_head */
 310           = BH_PrivateStart,
 311         BH_JWrite,              /* Being written to log (@@@ DEBUGGING) */
 312         BH_Freed,               /* Has been freed (truncated) */
 313         BH_Revoked,             /* Has been revoked from the log */
 314         BH_RevokeValid,         /* Revoked flag is valid */
 315         BH_JBDDirty,            /* Is dirty but journaled */
 316         BH_State,               /* Pins most journal_head state */
 317         BH_JournalHead,         /* Pins bh->b_private and jh->b_bh */
 318         BH_Unshadow,            /* Dummy bit, for BJ_Shadow wakeup filtering */
 319 };
 320
 321 BUFFER_FNS(JBD, jbd)
 322 BUFFER_FNS(JWrite, jwrite)
 323 BUFFER_FNS(JBDDirty, jbddirty)
 324 TAS_BUFFER_FNS(JBDDirty, jbddirty)
 325 BUFFER_FNS(Revoked, revoked)
 326 TAS_BUFFER_FNS(Revoked, revoked)
 327 BUFFER_FNS(RevokeValid, revokevalid)
 328 TAS_BUFFER_FNS(RevokeValid, revokevalid)
 329 BUFFER_FNS(Freed, freed)
 330
 331 static inline struct buffer_head *jh2bh(struct journal_head *jh)
 332 {
 333         return jh->b_bh;
 334 }
 335
 336 static inline struct journal_head *bh2jh(struct buffer_head *bh)
 337 {
 338         return bh->b_private;
 339 }
 340
 341 static inline void jbd_lock_bh_state(struct buffer_head *bh)
 342 {
 343         bit_spin_lock(BH_State, &bh->b_state);
 344 }
 345
 346 static inline int jbd_trylock_bh_state(struct buffer_head *bh)
 347 {
 348         return bit_spin_trylock(BH_State, &bh->b_state);
 349 }
 350
 351 static inline int jbd_is_locked_bh_state(struct buffer_head *bh)
 352 {
 353         return bit_spin_is_locked(BH_State, &bh->b_state);
 354 }
 355
 356 static inline void jbd_unlock_bh_state(struct buffer_head *bh)
 357 {
 358         bit_spin_unlock(BH_State, &bh->b_state);
 359 }
 360
 361 static inline void jbd_lock_bh_journal_head(struct buffer_head *bh)
 362 {
 363         bit_spin_lock(BH_JournalHead, &bh->b_state);
 364 }
 365
 366 static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh)
 367 {
 368         bit_spin_unlock(BH_JournalHead, &bh->b_state);
 369 }
 370
 371 struct jbd2_revoke_table_s;
 372
 373 /**
 374  * struct handle_s - The handle_s type is the concrete type associated with
 375  *     handle_t.
 376  * @h_transaction: Which compound transaction is this update a part of?
 377  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
 378  * @h_ref: Reference count on this handle
 379  * @h_err: Field for caller's use to track errors through large fs operations
 380  * @h_sync: flag for sync-on-close
 381  * @h_jdata: flag to force data journaling
 382  * @h_aborted: flag indicating fatal error on handle
 383  **/
 384
 385 /* Docbook can't yet cope with the bit fields, but will leave the documentation
 386  * in so it can be fixed later.
 387  */
 388
 389 struct handle_s
 390 {
 391         /* Which compound transaction is this update a part of? */
 392         transaction_t           *h_transaction;
 393
 394         /* Number of remaining buffers we are allowed to dirty: */
 395         int                     h_buffer_credits;
 396
 397         /* Reference count on this handle */
 398         int                     h_ref;
 399
 400         /* Field for caller's use to track errors through large fs */
 401         /* operations */
 402         int                     h_err;
 403
 404         /* Flags [no locking] */
 405         unsigned int    h_sync:         1;      /* sync-on-close */
 406         unsigned int    h_jdata:        1;      /* force data journaling */
 407         unsigned int    h_aborted:      1;      /* fatal error on handle */
 408 };
 409
 410
 411 /* The transaction_t type is the guts of the journaling mechanism.  It
 412  * tracks a compound transaction through its various states:
 413  *
 414  * RUNNING:     accepting new updates
 415  * LOCKED:      Updates still running but we don't accept new ones
 416  * RUNDOWN:     Updates are tidying up but have finished requesting
 417  *              new buffers to modify (state not used for now)
 418  * FLUSH:       All updates complete, but we are still writing to disk
 419  * COMMIT:      All data on disk, writing commit record
 420  * FINISHED:    We still have to keep the transaction for checkpointing.
 421  *
 422  * The transaction keeps track of all of the buffers modified by a
 423  * running transaction, and all of the buffers committed but not yet
 424  * flushed to home for finished transactions.
 425  */
 426
 427 /*
 428  * Lock ranking:
 429  *
 430  *    j_list_lock
 431  *      ->jbd_lock_bh_journal_head()    (This is "innermost")
 432  *
 433  *    j_state_lock
 434  *    ->jbd_lock_bh_state()
 435  *
 436  *    jbd_lock_bh_state()
 437  *    ->j_list_lock
 438  *
 439  *    j_state_lock
 440  *    ->t_handle_lock
 441  *
 442  *    j_state_lock
 443  *    ->j_list_lock                     (journal_unmap_buffer)
 444  *
 445  */
 446
 447 struct transaction_s
 448 {
 449         /* Pointer to the journal for this transaction. [no locking] */
 450         journal_t               *t_journal;
 451
 452         /* Sequence number for this transaction [no locking] */
 453         tid_t                   t_tid;
 454
 455         /*
 456          * Transaction's current state
 457          * [no locking - only kjournald2 alters this]
 458          * FIXME: needs barriers
 459          * KLUDGE: [use j_state_lock]
 460          */
 461         enum {
 462                 T_RUNNING,
 463                 T_LOCKED,
 464                 T_RUNDOWN,
 465                 T_FLUSH,
 466                 T_COMMIT,
 467                 T_FINISHED
 468         }                       t_state;
 469
 470         /*
 471          * Where in the log does this transaction's commit start? [no locking]
 472          */
 473         unsigned long           t_log_start;
 474
 475         /* Number of buffers on the t_buffers list [j_list_lock] */
 476         int                     t_nr_buffers;
 477
 478         /*
 479          * Doubly-linked circular list of all buffers reserved but not yet
 480          * modified by this transaction [j_list_lock]
 481          */
 482         struct journal_head     *t_reserved_list;
 483
 484         /*
 485          * Doubly-linked circular list of all buffers under writeout during
 486          * commit [j_list_lock]
 487          */
 488         struct journal_head     *t_locked_list;
 489
 490         /*
 491          * Doubly-linked circular list of all metadata buffers owned by this
 492          * transaction [j_list_lock]
 493          */
 494         struct journal_head     *t_buffers;
 495
 496         /*
 497          * Doubly-linked circular list of all data buffers still to be
 498          * flushed before this transaction can be committed [j_list_lock]
 499          */
 500         struct journal_head     *t_sync_datalist;
 501
 502         /*
 503          * Doubly-linked circular list of all forget buffers (superseded
 504          * buffers which we can un-checkpoint once this transaction commits)
 505          * [j_list_lock]
 506          */
 507         struct journal_head     *t_forget;
 508
 509         /*
 510          * Doubly-linked circular list of all buffers still to be flushed before
 511          * this transaction can be checkpointed. [j_list_lock]
 512          */
 513         struct journal_head     *t_checkpoint_list;
 514
 515         /*
 516          * Doubly-linked circular list of all buffers submitted for IO while
 517          * checkpointing. [j_list_lock]
 518          */
 519         struct journal_head     *t_checkpoint_io_list;
 520
 521         /*
 522          * Doubly-linked circular list of temporary buffers currently undergoing
 523          * IO in the log [j_list_lock]
 524          */
 525         struct journal_head     *t_iobuf_list;
 526
 527         /*
 528          * Doubly-linked circular list of metadata buffers being shadowed by log
 529          * IO.  The IO buffers on the iobuf list and the shadow buffers on this
 530          * list match each other one for one at all times. [j_list_lock]
 531          */
 532         struct journal_head     *t_shadow_list;
 533
 534         /*
 535          * Doubly-linked circular list of control buffers being written to the
 536          * log. [j_list_lock]
 537          */
 538         struct journal_head     *t_log_list;
 539
 540         /*
 541          * Protects info related to handles
 542          */
 543         spinlock_t              t_handle_lock;
 544
 545         /*
 546          * Number of outstanding updates running on this transaction
 547          * [t_handle_lock]
 548          */
 549         int                     t_updates;
 550
 551         /*
 552          * Number of buffers reserved for use by all handles in this transaction
 553          * handle but not yet modified. [t_handle_lock]
 554          */
 555         int                     t_outstanding_credits;
 556
 557         /*
 558          * Forward and backward links for the circular list of all transactions
 559          * awaiting checkpoint. [j_list_lock]
 560          */
 561         transaction_t           *t_cpnext, *t_cpprev;
 562
 563         /*
 564          * When will the transaction expire (become due for commit), in jiffies?
 565          * [no locking]
 566          */
 567         unsigned long           t_expires;
 568
 569         /*
 570          * How many handles used this transaction? [t_handle_lock]
 571          */
 572         int t_handle_count;
 573
 574 };
 575
 576 /**
 577  * struct journal_s - The journal_s type is the concrete type associated with
 578  *     journal_t.
 579  * @j_flags:  General journaling state flags
 580  * @j_errno:  Is there an outstanding uncleared error on the journal (from a
 581  *     prior abort)?
 582  * @j_sb_buffer: First part of superblock buffer
 583  * @j_superblock: Second part of superblock buffer
 584  * @j_format_version: Version of the superblock format
 585  * @j_state_lock: Protect the various scalars in the journal
 586  * @j_barrier_count:  Number of processes waiting to create a barrier lock
 587  * @j_barrier: The barrier lock itself
 588  * @j_running_transaction: The current running transaction..
 589  * @j_committing_transaction: the transaction we are pushing to disk
 590  * @j_checkpoint_transactions: a linked circular list of all transactions
 591  *  waiting for checkpointing
 592  * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
 593  *  to start committing, or for a barrier lock to be released
 594  * @j_wait_logspace: Wait queue for waiting for checkpointing to complete
 595  * @j_wait_done_commit: Wait queue for waiting for commit to complete
 596  * @j_wait_checkpoint:  Wait queue to trigger checkpointing
 597  * @j_wait_commit: Wait queue to trigger commit
 598  * @j_wait_updates: Wait queue to wait for updates to complete
 599  * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
 600  * @j_head: Journal head - identifies the first unused block in the journal
 601  * @j_tail: Journal tail - identifies the oldest still-used block in the
 602  *  journal.
 603  * @j_free: Journal free - how many free blocks are there in the journal?
 604  * @j_first: The block number of the first usable block
 605  * @j_last: The block number one beyond the last usable block
 606  * @j_dev: Device where we store the journal
 607  * @j_blocksize: blocksize for the location where we store the journal.
 608  * @j_blk_offset: starting block offset for into the device where we store the
 609  *     journal
 610  * @j_fs_dev: Device which holds the client fs.  For internal journal this will
 611  *     be equal to j_dev
 612  * @j_maxlen: Total maximum capacity of the journal region on disk.
 613  * @j_list_lock: Protects the buffer lists and internal buffer state.
 614  * @j_inode: Optional inode where we store the journal.  If present, all journal
 615  *     block numbers are mapped into this inode via bmap().
 616  * @j_tail_sequence:  Sequence number of the oldest transaction in the log
 617  * @j_transaction_sequence: Sequence number of the next transaction to grant
 618  * @j_commit_sequence: Sequence number of the most recently committed
 619  *  transaction
 620  * @j_commit_request: Sequence number of the most recent transaction wanting
 621  *     commit
 622  * @j_uuid: Uuid of client object.
 623  * @j_task: Pointer to the current commit thread for this journal
 624  * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
 625  *     single compound commit transaction
 626  * @j_commit_interval: What is the maximum transaction lifetime before we begin
 627  *  a commit?
 628  * @j_commit_timer:  The timer used to wakeup the commit thread
 629  * @j_revoke_lock: Protect the revoke table
 630  * @j_revoke: The revoke table - maintains the list of revoked blocks in the
 631  *     current transaction.
 632  * @j_revoke_table: alternate revoke tables for j_revoke
 633  * @j_wbuf: array of buffer_heads for jbd2_journal_commit_transaction
 634  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
 635  *      number that will fit in j_blocksize
 636  * @j_last_sync_writer: most recent pid which did a synchronous write
 637  * @j_private: An opaque pointer to fs-private information.
 638  */
 639
 640 struct journal_s
 641 {
 642         /* General journaling state flags [j_state_lock] */
 643         unsigned long           j_flags;
 644
 645         /*
 646          * Is there an outstanding uncleared error on the journal (from a prior
 647          * abort)? [j_state_lock]
 648          */
 649         int                     j_errno;
 650
 651         /* The superblock buffer */
 652         struct buffer_head      *j_sb_buffer;
 653         journal_superblock_t    *j_superblock;
 654
 655         /* Version of the superblock format */
 656         int                     j_format_version;
 657
 658         /*
 659          * Protect the various scalars in the journal
 660          */
 661         spinlock_t              j_state_lock;
 662
 663         /*
 664          * Number of processes waiting to create a barrier lock [j_state_lock]
 665          */
 666         int                     j_barrier_count;
 667
 668         /* The barrier lock itself */
 669         struct mutex            j_barrier;
 670
 671         /*
 672          * Transactions: The current running transaction...
 673          * [j_state_lock] [caller holding open handle]
 674          */
 675         transaction_t           *j_running_transaction;
 676
 677         /*
 678          * the transaction we are pushing to disk
 679          * [j_state_lock] [caller holding open handle]
 680          */
 681         transaction_t           *j_committing_transaction;
 682
 683         /*
 684          * ... and a linked circular list of all transactions waiting for
 685          * checkpointing. [j_list_lock]
 686          */
 687         transaction_t           *j_checkpoint_transactions;
 688
 689         /*
 690          * Wait queue for waiting for a locked transaction to start committing,
 691          * or for a barrier lock to be released
 692          */
 693         wait_queue_head_t       j_wait_transaction_locked;
 694
 695         /* Wait queue for waiting for checkpointing to complete */
 696         wait_queue_head_t       j_wait_logspace;
 697
 698         /* Wait queue for waiting for commit to complete */
 699         wait_queue_head_t       j_wait_done_commit;
 700
 701         /* Wait queue to trigger checkpointing */
 702         wait_queue_head_t       j_wait_checkpoint;
 703
 704         /* Wait queue to trigger commit */
 705         wait_queue_head_t       j_wait_commit;
 706
 707         /* Wait queue to wait for updates to complete */
 708         wait_queue_head_t       j_wait_updates;
 709
 710         /* Semaphore for locking against concurrent checkpoints */
 711         struct mutex            j_checkpoint_mutex;
 712
 713         /*
 714          * Journal head: identifies the first unused block in the journal.
 715          * [j_state_lock]
 716          */
 717         unsigned long           j_head;
 718
 719         /*
 720          * Journal tail: identifies the oldest still-used block in the journal.
 721          * [j_state_lock]
 722          */
 723         unsigned long           j_tail;
 724
 725         /*
 726          * Journal free: how many free blocks are there in the journal?
 727          * [j_state_lock]
 728          */
 729         unsigned long           j_free;
 730
 731         /*
 732          * Journal start and end: the block numbers of the first usable block
 733          * and one beyond the last usable block in the journal. [j_state_lock]
 734          */
 735         unsigned long           j_first;
 736         unsigned long           j_last;
 737
 738         /*
 739          * Device, blocksize and starting block offset for the location where we
 740          * store the journal.
 741          */
 742         struct block_device     *j_dev;
 743         int                     j_blocksize;
 744         unsigned long long              j_blk_offset;
 745
 746         /*
 747          * Device which holds the client fs.  For internal journal this will be
 748          * equal to j_dev.
 749          */
 750         struct block_device     *j_fs_dev;
 751
 752         /* Total maximum capacity of the journal region on disk. */
 753         unsigned int            j_maxlen;
 754
 755         /*
 756          * Protects the buffer lists and internal buffer state.
 757          */
 758         spinlock_t              j_list_lock;
 759
 760         /* Optional inode where we store the journal.  If present, all */
 761         /* journal block numbers are mapped into this inode via */
 762         /* bmap(). */
 763         struct inode            *j_inode;
 764
 765         /*
 766          * Sequence number of the oldest transaction in the log [j_state_lock]
 767          */
 768         tid_t                   j_tail_sequence;
 769
 770         /*
 771          * Sequence number of the next transaction to grant [j_state_lock]
 772          */
 773         tid_t                   j_transaction_sequence;
 774
 775         /*
 776          * Sequence number of the most recently committed transaction
 777          * [j_state_lock].
 778          */
 779         tid_t                   j_commit_sequence;
 780
 781         /*
 782          * Sequence number of the most recent transaction wanting commit
 783          * [j_state_lock]
 784          */
 785         tid_t                   j_commit_request;
 786
 787         /*
 788          * Journal uuid: identifies the object (filesystem, LVM volume etc)
 789          * backed by this journal.  This will eventually be replaced by an array
 790          * of uuids, allowing us to index multiple devices within a single
 791          * journal and to perform atomic updates across them.
 792          */
 793         __u8                    j_uuid[16];
 794
 795         /* Pointer to the current commit thread for this journal */
 796         struct task_struct      *j_task;
 797
 798         /*
 799          * Maximum number of metadata buffers to allow in a single compound
 800          * commit transaction
 801          */
 802         int                     j_max_transaction_buffers;
 803
 804         /*
 805          * What is the maximum transaction lifetime before we begin a commit?
 806          */
 807         unsigned long           j_commit_interval;
 808
 809         /* The timer used to wakeup the commit thread: */
 810         struct timer_list       j_commit_timer;
 811
 812         /*
 813          * The revoke table: maintains the list of revoked blocks in the
 814          * current transaction.  [j_revoke_lock]
 815          */
 816         spinlock_t              j_revoke_lock;
 817         struct jbd2_revoke_table_s *j_revoke;
 818         struct jbd2_revoke_table_s *j_revoke_table[2];
 819
 820         /*
 821          * array of bhs for jbd2_journal_commit_transaction
 822          */
 823         struct buffer_head      **j_wbuf;
 824         int                     j_wbufsize;
 825
 826         pid_t                   j_last_sync_writer;
 827
 828         /*
 829          * An opaque pointer to fs-private information.  ext3 puts its
 830          * superblock pointer here
 831          */
 832         void *j_private;
 833 };
 834
 835 /*
 836  * Journal flag definitions
 837  */
 838 #define JBD2_UNMOUNT    0x001   /* Journal thread is being destroyed */
 839 #define JBD2_ABORT      0x002   /* Journaling has been aborted for errors. */
 840 #define JBD2_ACK_ERR    0x004   /* The errno in the sb has been acked */
 841 #define JBD2_FLUSHED    0x008   /* The journal superblock has been flushed */
 842 #define JBD2_LOADED     0x010   /* The journal superblock has been loaded */
 843 #define JBD2_BARRIER    0x020   /* Use IDE barriers */
 844
 845 /*
 846  * Function declarations for the journaling transaction and buffer
 847  * management
 848  */
 849
 850 /* Filing buffers */
 851 extern void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
 852 extern void jbd2_journal_unfile_buffer(journal_t *, struct journal_head *);
 853 extern void __jbd2_journal_unfile_buffer(struct journal_head *);
 854 extern void __jbd2_journal_refile_buffer(struct journal_head *);
 855 extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *);
 856 extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
 857 extern void __journal_free_buffer(struct journal_head *bh);
 858 extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
 859 extern void __journal_clean_data_list(transaction_t *transaction);
 860
 861 /* Log buffer allocation */
 862 extern struct journal_head * jbd2_journal_get_descriptor_buffer(journal_t *);
 863 int jbd2_journal_next_log_block(journal_t *, unsigned long long *);
 864
 865 /* Commit management */
 866 extern void jbd2_journal_commit_transaction(journal_t *);
 867
 868 /* Checkpoint list management */
 869 int __jbd2_journal_clean_checkpoint_list(journal_t *journal);
 870 int __jbd2_journal_remove_checkpoint(struct journal_head *);
 871 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
 872
 873 /* Buffer IO */
 874 extern int
 875 jbd2_journal_write_metadata_buffer(transaction_t          *transaction,
 876                               struct journal_head  *jh_in,
 877                               struct journal_head **jh_out,
 878                               unsigned long long   blocknr);
 879
 880 /* Transaction locking */
 881 extern void             __wait_on_journal (journal_t *);
 882
 883 /*
 884  * Journal locking.
 885  *
 886  * We need to lock the journal during transaction state changes so that nobody
 887  * ever tries to take a handle on the running transaction while we are in the
 888  * middle of moving it to the commit phase.  j_state_lock does this.
 889  *
 890  * Note that the locking is completely interrupt unsafe.  We never touch
 891  * journal structures from interrupts.
 892  */
 893
 894 static inline handle_t *journal_current_handle(void)
 895 {
 896         return current->journal_info;
 897 }
 898
 899 /* The journaling code user interface:
 900  *
 901  * Create and destroy handles
 902  * Register buffer modifications against the current transaction.
 903  */
 904
 905 extern handle_t *jbd2_journal_start(journal_t *, int nblocks);
 906 extern int       jbd2_journal_restart (handle_t *, int nblocks);
 907 extern int       jbd2_journal_extend (handle_t *, int nblocks);
 908 extern int       jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
 909 extern int       jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
 910 extern int       jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
 911 extern int       jbd2_journal_dirty_data (handle_t *, struct buffer_head *);
 912 extern int       jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
 913 extern void      jbd2_journal_release_buffer (handle_t *, struct buffer_head *);
 914 extern int       jbd2_journal_forget (handle_t *, struct buffer_head *);
 915 extern void      journal_sync_buffer (struct buffer_head *);
 916 extern void      jbd2_journal_invalidatepage(journal_t *,
 917                                 struct page *, unsigned long);
 918 extern int       jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
 919 extern int       jbd2_journal_stop(handle_t *);
 920 extern int       jbd2_journal_flush (journal_t *);
 921 extern void      jbd2_journal_lock_updates (journal_t *);
 922 extern void      jbd2_journal_unlock_updates (journal_t *);
 923
 924 extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
 925                                 struct block_device *fs_dev,
 926                                 unsigned long long start, int len, int bsize);
 927 extern journal_t * jbd2_journal_init_inode (struct inode *);
 928 extern int         jbd2_journal_update_format (journal_t *);
 929 extern int         jbd2_journal_check_used_features
 930                    (journal_t *, unsigned long, unsigned long, unsigned long);
 931 extern int         jbd2_journal_check_available_features
 932                    (journal_t *, unsigned long, unsigned long, unsigned long);
 933 extern int         jbd2_journal_set_features
 934                    (journal_t *, unsigned long, unsigned long, unsigned long);
 935 extern int         jbd2_journal_create     (journal_t *);
 936 extern int         jbd2_journal_load       (journal_t *journal);
 937 extern void        jbd2_journal_destroy    (journal_t *);
 938 extern int         jbd2_journal_recover    (journal_t *journal);
 939 extern int         jbd2_journal_wipe       (journal_t *, int);
 940 extern int         jbd2_journal_skip_recovery   (journal_t *);
 941 extern void        jbd2_journal_update_superblock       (journal_t *, int);
 942 extern void        __jbd2_journal_abort_hard    (journal_t *);
 943 extern void        jbd2_journal_abort      (journal_t *, int);
 944 extern int         jbd2_journal_errno      (journal_t *);
 945 extern void        jbd2_journal_ack_err    (journal_t *);
 946 extern int         jbd2_journal_clear_err  (journal_t *);
 947 extern int         jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
 948 extern int         jbd2_journal_force_commit(journal_t *);
 949
 950 /*
 951  * journal_head management
 952  */
 953 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh);
 954 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh);
 955 void jbd2_journal_remove_journal_head(struct buffer_head *bh);
 956 void jbd2_journal_put_journal_head(struct journal_head *jh);
 957
 958 /*
 959  * handle management
 960  */
 961 extern kmem_cache_t *jbd2_handle_cache;
 962
 963 static inline handle_t *jbd_alloc_handle(gfp_t gfp_flags)
 964 {
 965         return kmem_cache_alloc(jbd2_handle_cache, gfp_flags);
 966 }
 967
 968 static inline void jbd_free_handle(handle_t *handle)
 969 {
 970         kmem_cache_free(jbd2_handle_cache, handle);
 971 }
 972
 973 /* Primary revoke support */
 974 #define JOURNAL_REVOKE_DEFAULT_HASH 256
 975 extern int         jbd2_journal_init_revoke(journal_t *, int);
 976 extern void        jbd2_journal_destroy_revoke_caches(void);
 977 extern int         jbd2_journal_init_revoke_caches(void);
 978
 979 extern void        jbd2_journal_destroy_revoke(journal_t *);
 980 extern int         jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *);
 981 extern int         jbd2_journal_cancel_revoke(handle_t *, struct journal_head *);
 982 extern void        jbd2_journal_write_revoke_records(journal_t *, transaction_t *);
 983
 984 /* Recovery revoke support */
 985 extern int      jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t);
 986 extern int      jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t);
 987 extern void     jbd2_journal_clear_revoke(journal_t *);
 988 extern void     jbd2_journal_switch_revoke_table(journal_t *journal);
 989
 990 /*
 991  * The log thread user interface:
 992  *
 993  * Request space in the current transaction, and force transaction commit
 994  * transitions on demand.
 995  */
 996
 997 int __jbd2_log_space_left(journal_t *); /* Called with journal locked */
 998 int jbd2_log_start_commit(journal_t *journal, tid_t tid);
 999 int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
1000 int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
1001 int jbd2_journal_force_commit_nested(journal_t *journal);
1002 int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
1003 int jbd2_log_do_checkpoint(journal_t *journal);
1004
1005 void __jbd2_log_wait_for_space(journal_t *journal);
1006 extern void     __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
1007 extern int      jbd2_cleanup_journal_tail(journal_t *);
1008
1009 /* Debugging code only: */
1010
1011 #define jbd_ENOSYS() \
1012 do {                                                                       \
1013         printk (KERN_ERR "JBD unimplemented function %s\n", __FUNCTION__); \
1014         current->state = TASK_UNINTERRUPTIBLE;                             \
1015         schedule();                                                        \
1016 } while (1)
1017
1018 /*
1019  * is_journal_abort
1020  *
1021  * Simple test wrapper function to test the JBD2_ABORT state flag.  This
1022  * bit, when set, indicates that we have had a fatal error somewhere,
1023  * either inside the journaling layer or indicated to us by the client
1024  * (eg. ext3), and that we and should not commit any further
1025  * transactions.
1026  */
1027
1028 static inline int is_journal_aborted(journal_t *journal)
1029 {
1030         return journal->j_flags & JBD2_ABORT;
1031 }
1032
1033 static inline int is_handle_aborted(handle_t *handle)
1034 {
1035         if (handle->h_aborted)
1036                 return 1;
1037         return is_journal_aborted(handle->h_transaction->t_journal);
1038 }
1039
1040 static inline void jbd2_journal_abort_handle(handle_t *handle)
1041 {
1042         handle->h_aborted = 1;
1043 }
1044
1045 #endif /* __KERNEL__   */
1046
1047 /* Comparison functions for transaction IDs: perform comparisons using
1048  * modulo arithmetic so that they work over sequence number wraps. */
1049
1050 static inline int tid_gt(tid_t x, tid_t y)
1051 {
1052         int difference = (x - y);
1053         return (difference > 0);
1054 }
1055
1056 static inline int tid_geq(tid_t x, tid_t y)
1057 {
1058         int difference = (x - y);
1059         return (difference >= 0);
1060 }
1061
1062 extern int jbd2_journal_blocks_per_page(struct inode *inode);
1063 extern size_t journal_tag_bytes(journal_t *journal);
1064
1065 /*
1066  * Return the minimum number of blocks which must be free in the journal
1067  * before a new transaction may be started.  Must be called under j_state_lock.
1068  */
1069 static inline int jbd_space_needed(journal_t *journal)
1070 {
1071         int nblocks = journal->j_max_transaction_buffers;
1072         if (journal->j_committing_transaction)
1073                 nblocks += journal->j_committing_transaction->
1074                                         t_outstanding_credits;
1075         return nblocks;
1076 }
1077
1078 /*
1079  * Definitions which augment the buffer_head layer
1080  */
1081
1082 /* journaling buffer types */
1083 #define BJ_None         0       /* Not journaled */
1084 #define BJ_SyncData     1       /* Normal data: flush before commit */
1085 #define BJ_Metadata     2       /* Normal journaled metadata */
1086 #define BJ_Forget       3       /* Buffer superseded by this transaction */
1087 #define BJ_IO           4       /* Buffer is for temporary IO use */
1088 #define BJ_Shadow       5       /* Buffer contents being shadowed to the log */
1089 #define BJ_LogCtl       6       /* Buffer contains log descriptors */
1090 #define BJ_Reserved     7       /* Buffer is reserved for access by journal */
1091 #define BJ_Locked       8       /* Locked for I/O during commit */
1092 #define BJ_Types        9
1093
1094 extern int jbd_blocks_per_page(struct inode *inode);
1095
1096 #ifdef __KERNEL__
1097
1098 #define buffer_trace_init(bh)   do {} while (0)
1099 #define print_buffer_fields(bh) do {} while (0)
1100 #define print_buffer_trace(bh)  do {} while (0)
1101 #define BUFFER_TRACE(bh, info)  do {} while (0)
1102 #define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1103 #define JBUFFER_TRACE(jh, info) do {} while (0)
1104
1105 #endif  /* __KERNEL__ */
1106
1107 #endif  /* _LINUX_JBD_H */