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#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/slab.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 u8 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 3 150 151#define JBD2_CRC32_CHKSUM_SIZE 4 152 153#define JBD2_CHECKSUM_BYTES (32 / sizeof(u32)) 154/* 155 * Commit block header for storing transactional checksums: 156 */ 157struct commit_header { 158 __be32 h_magic; 159 __be32 h_blocktype; 160 __be32 h_sequence; 161 unsigned char h_chksum_type; 162 unsigned char h_chksum_size; 163 unsigned char h_padding[2]; 164 __be32 h_chksum[JBD2_CHECKSUM_BYTES]; 165 __be64 h_commit_sec; 166 __be32 h_commit_nsec; 167}; 168 169/* 170 * The block tag: used to describe a single buffer in the journal. 171 * t_blocknr_high is only used if INCOMPAT_64BIT is set, so this 172 * raw struct shouldn't be used for pointer math or sizeof() - use 173 * journal_tag_bytes(journal) instead to compute this. 174 */ 175typedef struct journal_block_tag_s 176{ 177 __be32 t_blocknr; /* The on-disk block number */ 178 __be32 t_flags; /* See below */ 179 __be32 t_blocknr_high; /* most-significant high 32bits. */ 180} journal_block_tag_t; 181 182#define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high)) 183#define JBD2_TAG_SIZE64 (sizeof(journal_block_tag_t)) 184 185/* 186 * The revoke descriptor: used on disk to describe a series of blocks to 187 * be revoked from the log 188 */ 189typedef struct jbd2_journal_revoke_header_s 190{ 191 journal_header_t r_header; 192 __be32 r_count; /* Count of bytes used in the block */ 193} jbd2_journal_revoke_header_t; 194 195 196/* Definitions for the journal tag flags word: */ 197#define JBD2_FLAG_ESCAPE 1 /* on-disk block is escaped */ 198#define JBD2_FLAG_SAME_UUID 2 /* block has same uuid as previous */ 199#define JBD2_FLAG_DELETED 4 /* block deleted by this transaction */ 200#define JBD2_FLAG_LAST_TAG 8 /* last tag in this descriptor block */ 201 202 203/* 204 * The journal superblock. All fields are in big-endian byte order. 205 */ 206typedef struct journal_superblock_s 207{ 208/* 0x0000 */ 209 journal_header_t s_header; 210 211/* 0x000C */ 212 /* Static information describing the journal */ 213 __be32 s_blocksize; /* journal device blocksize */ 214 __be32 s_maxlen; /* total blocks in journal file */ 215 __be32 s_first; /* first block of log information */ 216 217/* 0x0018 */ 218 /* Dynamic information describing the current state of the log */ 219 __be32 s_sequence; /* first commit ID expected in log */ 220 __be32 s_start; /* blocknr of start of log */ 221 222/* 0x0020 */ 223 /* Error value, as set by jbd2_journal_abort(). */ 224 __be32 s_errno; 225 226/* 0x0024 */ 227 /* Remaining fields are only valid in a version-2 superblock */ 228 __be32 s_feature_compat; /* compatible feature set */ 229 __be32 s_feature_incompat; /* incompatible feature set */ 230 __be32 s_feature_ro_compat; /* readonly-compatible feature set */ 231/* 0x0030 */ 232 __u8 s_uuid[16]; /* 128-bit uuid for journal */ 233 234/* 0x0040 */ 235 __be32 s_nr_users; /* Nr of filesystems sharing log */ 236 237 __be32 s_dynsuper; /* Blocknr of dynamic superblock copy*/ 238 239/* 0x0048 */ 240 __be32 s_max_transaction; /* Limit of journal blocks per trans.*/ 241 __be32 s_max_trans_data; /* Limit of data blocks per trans. */ 242 243/* 0x0050 */ 244 __u32 s_padding[44]; 245 246/* 0x0100 */ 247 __u8 s_users[16*48]; /* ids of all fs'es sharing the log */ 248/* 0x0400 */ 249} journal_superblock_t; 250 251#define JBD2_HAS_COMPAT_FEATURE(j,mask) \ 252 ((j)->j_format_version >= 2 && \ 253 ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask)))) 254#define JBD2_HAS_RO_COMPAT_FEATURE(j,mask) \ 255 ((j)->j_format_version >= 2 && \ 256 ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask)))) 257#define JBD2_HAS_INCOMPAT_FEATURE(j,mask) \ 258 ((j)->j_format_version >= 2 && \ 259 ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask)))) 260 261#define JBD2_FEATURE_COMPAT_CHECKSUM 0x00000001 262 263#define JBD2_FEATURE_INCOMPAT_REVOKE 0x00000001 264#define JBD2_FEATURE_INCOMPAT_64BIT 0x00000002 265#define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT 0x00000004 266 267/* Features known to this kernel version: */ 268#define JBD2_KNOWN_COMPAT_FEATURES JBD2_FEATURE_COMPAT_CHECKSUM 269#define JBD2_KNOWN_ROCOMPAT_FEATURES 0 270#define JBD2_KNOWN_INCOMPAT_FEATURES (JBD2_FEATURE_INCOMPAT_REVOKE | \ 271 JBD2_FEATURE_INCOMPAT_64BIT | \ 272 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT) 273 274#ifdef __KERNEL__ 275 276#include <linux/fs.h> 277#include <linux/sched.h> 278 279#define J_ASSERT(assert) BUG_ON(!(assert)) 280 281#define J_ASSERT_BH(bh, expr) J_ASSERT(expr) 282#define J_ASSERT_JH(jh, expr) J_ASSERT(expr) 283 284#if defined(JBD2_PARANOID_IOFAIL) 285#define J_EXPECT(expr, why...) J_ASSERT(expr) 286#define J_EXPECT_BH(bh, expr, why...) J_ASSERT_BH(bh, expr) 287#define J_EXPECT_JH(jh, expr, why...) J_ASSERT_JH(jh, expr) 288#else 289#define __journal_expect(expr, why...) \ 290 ({ \ 291 int val = (expr); \ 292 if (!val) { \ 293 printk(KERN_ERR \ 294 "JBD2 unexpected failure: %s: %s;\n", \ 295 __func__, #expr); \ 296 printk(KERN_ERR why "\n"); \ 297 } \ 298 val; \ 299 }) 300#define J_EXPECT(expr, why...) __journal_expect(expr, ## why) 301#define J_EXPECT_BH(bh, expr, why...) __journal_expect(expr, ## why) 302#define J_EXPECT_JH(jh, expr, why...) __journal_expect(expr, ## why) 303#endif 304 305enum jbd_state_bits { 306 BH_JBD /* Has an attached ext3 journal_head */ 307 = BH_PrivateStart, 308 BH_JWrite, /* Being written to log (@@@ DEBUGGING) */ 309 BH_Freed, /* Has been freed (truncated) */ 310 BH_Revoked, /* Has been revoked from the log */ 311 BH_RevokeValid, /* Revoked flag is valid */ 312 BH_JBDDirty, /* Is dirty but journaled */ 313 BH_State, /* Pins most journal_head state */ 314 BH_JournalHead, /* Pins bh->b_private and jh->b_bh */ 315 BH_Unshadow, /* Dummy bit, for BJ_Shadow wakeup filtering */ 316 BH_JBDPrivateStart, /* First bit available for private use by FS */ 317}; 318 319BUFFER_FNS(JBD, jbd) 320BUFFER_FNS(JWrite, jwrite) 321BUFFER_FNS(JBDDirty, jbddirty) 322TAS_BUFFER_FNS(JBDDirty, jbddirty) 323BUFFER_FNS(Revoked, revoked) 324TAS_BUFFER_FNS(Revoked, revoked) 325BUFFER_FNS(RevokeValid, revokevalid) 326TAS_BUFFER_FNS(RevokeValid, revokevalid) 327BUFFER_FNS(Freed, freed) 328 329static inline struct buffer_head *jh2bh(struct journal_head *jh) 330{ 331 return jh->b_bh; 332} 333 334static inline struct journal_head *bh2jh(struct buffer_head *bh) 335{ 336 return bh->b_private; 337} 338 339static inline void jbd_lock_bh_state(struct buffer_head *bh) 340{ 341 bit_spin_lock(BH_State, &bh->b_state); 342} 343 344static inline int jbd_trylock_bh_state(struct buffer_head *bh) 345{ 346 return bit_spin_trylock(BH_State, &bh->b_state); 347} 348 349static inline int jbd_is_locked_bh_state(struct buffer_head *bh) 350{ 351 return bit_spin_is_locked(BH_State, &bh->b_state); 352} 353 354static inline void jbd_unlock_bh_state(struct buffer_head *bh) 355{ 356 bit_spin_unlock(BH_State, &bh->b_state); 357} 358 359static inline void jbd_lock_bh_journal_head(struct buffer_head *bh) 360{ 361 bit_spin_lock(BH_JournalHead, &bh->b_state); 362} 363 364static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh) 365{ 366 bit_spin_unlock(BH_JournalHead, &bh->b_state); 367} 368 369/* Flags in jbd_inode->i_flags */ 370#define __JI_COMMIT_RUNNING 0 371/* Commit of the inode data in progress. We use this flag to protect us from 372 * concurrent deletion of inode. We cannot use reference to inode for this 373 * since we cannot afford doing last iput() on behalf of kjournald 374 */ 375#define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING) 376 377/** 378 * struct jbd_inode is the structure linking inodes in ordered mode 379 * present in a transaction so that we can sync them during commit. 380 */ 381struct jbd2_inode { 382 /* Which transaction does this inode belong to? Either the running 383 * transaction or the committing one. [j_list_lock] */ 384 transaction_t *i_transaction; 385 386 /* Pointer to the running transaction modifying inode's data in case 387 * there is already a committing transaction touching it. [j_list_lock] */ 388 transaction_t *i_next_transaction; 389 390 /* List of inodes in the i_transaction [j_list_lock] */ 391 struct list_head i_list; 392 393 /* VFS inode this inode belongs to [constant during the lifetime 394 * of the structure] */ 395 struct inode *i_vfs_inode; 396 397 /* Flags of inode [j_list_lock] */ 398 unsigned long i_flags; 399}; 400 401struct jbd2_revoke_table_s; 402 403/** 404 * struct handle_s - The handle_s type is the concrete type associated with 405 * handle_t. 406 * @h_transaction: Which compound transaction is this update a part of? 407 * @h_buffer_credits: Number of remaining buffers we are allowed to dirty. 408 * @h_ref: Reference count on this handle 409 * @h_err: Field for caller's use to track errors through large fs operations 410 * @h_sync: flag for sync-on-close 411 * @h_jdata: flag to force data journaling 412 * @h_aborted: flag indicating fatal error on handle 413 **/ 414 415/* Docbook can't yet cope with the bit fields, but will leave the documentation 416 * in so it can be fixed later. 417 */ 418 419struct jbd2_journal_handle 420{ 421 /* Which compound transaction is this update a part of? */ 422 transaction_t *h_transaction; 423 424 /* Number of remaining buffers we are allowed to dirty: */ 425 int h_buffer_credits; 426 427 /* Reference count on this handle */ 428 int h_ref; 429 430 /* Field for caller's use to track errors through large fs */ 431 /* operations */ 432 int h_err; 433 434 /* Flags [no locking] */ 435 unsigned int h_sync:1; /* sync-on-close */ 436 unsigned int h_jdata:1; /* force data journaling */ 437 unsigned int h_aborted:1; /* fatal error on handle */ 438 unsigned int h_cowing:1; /* COWing block to snapshot */ 439 440 /* Number of buffers requested by user: 441 * (before adding the COW credits factor) */ 442 unsigned int h_base_credits:14; 443 444 /* Number of buffers the user is allowed to dirty: 445 * (counts only buffers dirtied when !h_cowing) */ 446 unsigned int h_user_credits:14; 447 448 449#ifdef CONFIG_DEBUG_LOCK_ALLOC 450 struct lockdep_map h_lockdep_map; 451#endif 452 453#ifdef CONFIG_JBD2_DEBUG 454 /* COW debugging counters: */ 455 unsigned int h_cow_moved; /* blocks moved to snapshot */ 456 unsigned int h_cow_copied; /* blocks copied to snapshot */ 457 unsigned int h_cow_ok_jh; /* blocks already COWed during current 458 transaction */ 459 unsigned int h_cow_ok_bitmap; /* blocks not set in COW bitmap */ 460 unsigned int h_cow_ok_mapped;/* blocks already mapped in snapshot */ 461 unsigned int h_cow_bitmaps; /* COW bitmaps created */ 462 unsigned int h_cow_excluded; /* blocks set in exclude bitmap */ 463#endif 464}; 465 466 467/* 468 * Some stats for checkpoint phase 469 */ 470struct transaction_chp_stats_s { 471 unsigned long cs_chp_time; 472 __u32 cs_forced_to_close; 473 __u32 cs_written; 474 __u32 cs_dropped; 475}; 476 477/* The transaction_t type is the guts of the journaling mechanism. It 478 * tracks a compound transaction through its various states: 479 * 480 * RUNNING: accepting new updates 481 * LOCKED: Updates still running but we don't accept new ones 482 * RUNDOWN: Updates are tidying up but have finished requesting 483 * new buffers to modify (state not used for now) 484 * FLUSH: All updates complete, but we are still writing to disk 485 * COMMIT: All data on disk, writing commit record 486 * FINISHED: We still have to keep the transaction for checkpointing. 487 * 488 * The transaction keeps track of all of the buffers modified by a 489 * running transaction, and all of the buffers committed but not yet 490 * flushed to home for finished transactions. 491 */ 492 493/* 494 * Lock ranking: 495 * 496 * j_list_lock 497 * ->jbd_lock_bh_journal_head() (This is "innermost") 498 * 499 * j_state_lock 500 * ->jbd_lock_bh_state() 501 * 502 * jbd_lock_bh_state() 503 * ->j_list_lock 504 * 505 * j_state_lock 506 * ->t_handle_lock 507 * 508 * j_state_lock 509 * ->j_list_lock (journal_unmap_buffer) 510 * 511 */ 512 513struct transaction_s 514{ 515 /* Pointer to the journal for this transaction. [no locking] */ 516 journal_t *t_journal; 517 518 /* Sequence number for this transaction [no locking] */ 519 tid_t t_tid; 520 521 /* 522 * Transaction's current state 523 * [no locking - only kjournald2 alters this] 524 * [j_list_lock] guards transition of a transaction into T_FINISHED 525 * state and subsequent call of __jbd2_journal_drop_transaction() 526 * FIXME: needs barriers 527 * KLUDGE: [use j_state_lock] 528 */ 529 enum { 530 T_RUNNING, 531 T_LOCKED, 532 T_FLUSH, 533 T_COMMIT, 534 T_COMMIT_DFLUSH, 535 T_COMMIT_JFLUSH, 536 T_FINISHED 537 } t_state; 538 539 /* 540 * Where in the log does this transaction's commit start? [no locking] 541 */ 542 unsigned long t_log_start; 543 544 /* Number of buffers on the t_buffers list [j_list_lock] */ 545 int t_nr_buffers; 546 547 /* 548 * Doubly-linked circular list of all buffers reserved but not yet 549 * modified by this transaction [j_list_lock] 550 */ 551 struct journal_head *t_reserved_list; 552 553 /* 554 * Doubly-linked circular list of all metadata buffers owned by this 555 * transaction [j_list_lock] 556 */ 557 struct journal_head *t_buffers; 558 559 /* 560 * Doubly-linked circular list of all forget buffers (superseded 561 * buffers which we can un-checkpoint once this transaction commits) 562 * [j_list_lock] 563 */ 564 struct journal_head *t_forget; 565 566 /* 567 * Doubly-linked circular list of all buffers still to be flushed before 568 * this transaction can be checkpointed. [j_list_lock] 569 */ 570 struct journal_head *t_checkpoint_list; 571 572 /* 573 * Doubly-linked circular list of all buffers submitted for IO while 574 * checkpointing. [j_list_lock] 575 */ 576 struct journal_head *t_checkpoint_io_list; 577 578 /* 579 * Doubly-linked circular list of temporary buffers currently undergoing 580 * IO in the log [j_list_lock] 581 */ 582 struct journal_head *t_iobuf_list; 583 584 /* 585 * Doubly-linked circular list of metadata buffers being shadowed by log 586 * IO. The IO buffers on the iobuf list and the shadow buffers on this 587 * list match each other one for one at all times. [j_list_lock] 588 */ 589 struct journal_head *t_shadow_list; 590 591 /* 592 * Doubly-linked circular list of control buffers being written to the 593 * log. [j_list_lock] 594 */ 595 struct journal_head *t_log_list; 596 597 /* 598 * List of inodes whose data we've modified in data=ordered mode. 599 * [j_list_lock] 600 */ 601 struct list_head t_inode_list; 602 603 /* 604 * Protects info related to handles 605 */ 606 spinlock_t t_handle_lock; 607 608 /* 609 * Longest time some handle had to wait for running transaction 610 */ 611 unsigned long t_max_wait; 612 613 /* 614 * When transaction started 615 */ 616 unsigned long t_start; 617 618 /* 619 * Checkpointing stats [j_checkpoint_sem] 620 */ 621 struct transaction_chp_stats_s t_chp_stats; 622 623 /* 624 * Number of outstanding updates running on this transaction 625 * [t_handle_lock] 626 */ 627 atomic_t t_updates; 628 629 /* 630 * Number of buffers reserved for use by all handles in this transaction 631 * handle but not yet modified. [t_handle_lock] 632 */ 633 atomic_t t_outstanding_credits; 634 635 /* 636 * Forward and backward links for the circular list of all transactions 637 * awaiting checkpoint. [j_list_lock] 638 */ 639 transaction_t *t_cpnext, *t_cpprev; 640 641 /* 642 * When will the transaction expire (become due for commit), in jiffies? 643 * [no locking] 644 */ 645 unsigned long t_expires; 646 647 /* 648 * When this transaction started, in nanoseconds [no locking] 649 */ 650 ktime_t t_start_time; 651 652 /* 653 * How many handles used this transaction? [t_handle_lock] 654 */ 655 atomic_t t_handle_count; 656 657 /* 658 * This transaction is being forced and some process is 659 * waiting for it to finish. 660 */ 661 unsigned int t_synchronous_commit:1; 662 663 /* Disk flush needs to be sent to fs partition [no locking] */ 664 int t_need_data_flush; 665 666 /* 667 * For use by the filesystem to store fs-specific data 668 * structures associated with the transaction 669 */ 670 struct list_head t_private_list; 671}; 672 673struct transaction_run_stats_s { 674 unsigned long rs_wait; 675 unsigned long rs_running; 676 unsigned long rs_locked; 677 unsigned long rs_flushing; 678 unsigned long rs_logging; 679 680 __u32 rs_handle_count; 681 __u32 rs_blocks; 682 __u32 rs_blocks_logged; 683}; 684 685struct transaction_stats_s { 686 unsigned long ts_tid; 687 struct transaction_run_stats_s run; 688}; 689 690static inline unsigned long 691jbd2_time_diff(unsigned long start, unsigned long end) 692{ 693 if (end >= start) 694 return end - start; 695 696 return end + (MAX_JIFFY_OFFSET - start); 697} 698 699#define JBD2_NR_BATCH 64 700 701/** 702 * struct journal_s - The journal_s type is the concrete type associated with 703 * journal_t. 704 * @j_flags: General journaling state flags 705 * @j_errno: Is there an outstanding uncleared error on the journal (from a 706 * prior abort)? 707 * @j_sb_buffer: First part of superblock buffer 708 * @j_superblock: Second part of superblock buffer 709 * @j_format_version: Version of the superblock format 710 * @j_state_lock: Protect the various scalars in the journal 711 * @j_barrier_count: Number of processes waiting to create a barrier lock 712 * @j_barrier: The barrier lock itself 713 * @j_running_transaction: The current running transaction.. 714 * @j_committing_transaction: the transaction we are pushing to disk 715 * @j_checkpoint_transactions: a linked circular list of all transactions 716 * waiting for checkpointing 717 * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction 718 * to start committing, or for a barrier lock to be released 719 * @j_wait_logspace: Wait queue for waiting for checkpointing to complete 720 * @j_wait_done_commit: Wait queue for waiting for commit to complete 721 * @j_wait_checkpoint: Wait queue to trigger checkpointing 722 * @j_wait_commit: Wait queue to trigger commit 723 * @j_wait_updates: Wait queue to wait for updates to complete 724 * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints 725 * @j_head: Journal head - identifies the first unused block in the journal 726 * @j_tail: Journal tail - identifies the oldest still-used block in the 727 * journal. 728 * @j_free: Journal free - how many free blocks are there in the journal? 729 * @j_first: The block number of the first usable block 730 * @j_last: The block number one beyond the last usable block 731 * @j_dev: Device where we store the journal 732 * @j_blocksize: blocksize for the location where we store the journal. 733 * @j_blk_offset: starting block offset for into the device where we store the 734 * journal 735 * @j_fs_dev: Device which holds the client fs. For internal journal this will 736 * be equal to j_dev 737 * @j_maxlen: Total maximum capacity of the journal region on disk. 738 * @j_list_lock: Protects the buffer lists and internal buffer state. 739 * @j_inode: Optional inode where we store the journal. If present, all journal 740 * block numbers are mapped into this inode via bmap(). 741 * @j_tail_sequence: Sequence number of the oldest transaction in the log 742 * @j_transaction_sequence: Sequence number of the next transaction to grant 743 * @j_commit_sequence: Sequence number of the most recently committed 744 * transaction 745 * @j_commit_request: Sequence number of the most recent transaction wanting 746 * commit 747 * @j_uuid: Uuid of client object. 748 * @j_task: Pointer to the current commit thread for this journal 749 * @j_max_transaction_buffers: Maximum number of metadata buffers to allow in a 750 * single compound commit transaction 751 * @j_commit_interval: What is the maximum transaction lifetime before we begin 752 * a commit? 753 * @j_commit_timer: The timer used to wakeup the commit thread 754 * @j_revoke_lock: Protect the revoke table 755 * @j_revoke: The revoke table - maintains the list of revoked blocks in the 756 * current transaction. 757 * @j_revoke_table: alternate revoke tables for j_revoke 758 * @j_wbuf: array of buffer_heads for jbd2_journal_commit_transaction 759 * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the 760 * number that will fit in j_blocksize 761 * @j_last_sync_writer: most recent pid which did a synchronous write 762 * @j_history: Buffer storing the transactions statistics history 763 * @j_history_max: Maximum number of transactions in the statistics history 764 * @j_history_cur: Current number of transactions in the statistics history 765 * @j_history_lock: Protect the transactions statistics history 766 * @j_proc_entry: procfs entry for the jbd statistics directory 767 * @j_stats: Overall statistics 768 * @j_private: An opaque pointer to fs-private information. 769 */ 770 771struct journal_s 772{ 773 /* General journaling state flags [j_state_lock] */ 774 unsigned long j_flags; 775 776 /* 777 * Is there an outstanding uncleared error on the journal (from a prior 778 * abort)? [j_state_lock] 779 */ 780 int j_errno; 781 782 /* The superblock buffer */ 783 struct buffer_head *j_sb_buffer; 784 journal_superblock_t *j_superblock; 785 786 /* Version of the superblock format */ 787 int j_format_version; 788 789 /* 790 * Protect the various scalars in the journal 791 */ 792 rwlock_t j_state_lock; 793 794 /* 795 * Number of processes waiting to create a barrier lock [j_state_lock] 796 */ 797 int j_barrier_count; 798 799 /* The barrier lock itself */ 800 struct mutex j_barrier; 801 802 /* 803 * Transactions: The current running transaction... 804 * [j_state_lock] [caller holding open handle] 805 */ 806 transaction_t *j_running_transaction; 807 808 /* 809 * the transaction we are pushing to disk 810 * [j_state_lock] [caller holding open handle] 811 */ 812 transaction_t *j_committing_transaction; 813 814 /* 815 * ... and a linked circular list of all transactions waiting for 816 * checkpointing. [j_list_lock] 817 */ 818 transaction_t *j_checkpoint_transactions; 819 820 /* 821 * Wait queue for waiting for a locked transaction to start committing, 822 * or for a barrier lock to be released 823 */ 824 wait_queue_head_t j_wait_transaction_locked; 825 826 /* Wait queue for waiting for checkpointing to complete */ 827 wait_queue_head_t j_wait_logspace; 828 829 /* Wait queue for waiting for commit to complete */ 830 wait_queue_head_t j_wait_done_commit; 831 832 /* Wait queue to trigger checkpointing */ 833 wait_queue_head_t j_wait_checkpoint; 834 835 /* Wait queue to trigger commit */ 836 wait_queue_head_t j_wait_commit; 837 838 /* Wait queue to wait for updates to complete */ 839 wait_queue_head_t j_wait_updates; 840 841 /* Semaphore for locking against concurrent checkpoints */ 842 struct mutex j_checkpoint_mutex; 843 844 /* 845 * List of buffer heads used by the checkpoint routine. This 846 * was moved from jbd2_log_do_checkpoint() to reduce stack 847 * usage. Access to this array is controlled by the 848 * j_checkpoint_mutex. [j_checkpoint_mutex] 849 */ 850 struct buffer_head *j_chkpt_bhs[JBD2_NR_BATCH]; 851 852 /* 853 * Journal head: identifies the first unused block in the journal. 854 * [j_state_lock] 855 */ 856 unsigned long j_head; 857 858 /* 859 * Journal tail: identifies the oldest still-used block in the journal. 860 * [j_state_lock] 861 */ 862 unsigned long j_tail; 863 864 /* 865 * Journal free: how many free blocks are there in the journal? 866 * [j_state_lock] 867 */ 868 unsigned long j_free; 869 870 /* 871 * Journal start and end: the block numbers of the first usable block 872 * and one beyond the last usable block in the journal. [j_state_lock] 873 */ 874 unsigned long j_first; 875 unsigned long j_last; 876 877 /* 878 * Device, blocksize and starting block offset for the location where we 879 * store the journal. 880 */ 881 struct block_device *j_dev; 882 int j_blocksize; 883 unsigned long long j_blk_offset; 884 char j_devname[BDEVNAME_SIZE+24]; 885 886 /* 887 * Device which holds the client fs. For internal journal this will be 888 * equal to j_dev. 889 */ 890 struct block_device *j_fs_dev; 891 892 /* Total maximum capacity of the journal region on disk. */ 893 unsigned int j_maxlen; 894 895 /* 896 * Protects the buffer lists and internal buffer state. 897 */ 898 spinlock_t j_list_lock; 899 900 /* Optional inode where we store the journal. If present, all */ 901 /* journal block numbers are mapped into this inode via */ 902 /* bmap(). */ 903 struct inode *j_inode; 904 905 /* 906 * Sequence number of the oldest transaction in the log [j_state_lock] 907 */ 908 tid_t j_tail_sequence; 909 910 /* 911 * Sequence number of the next transaction to grant [j_state_lock] 912 */ 913 tid_t j_transaction_sequence; 914 915 /* 916 * Sequence number of the most recently committed transaction 917 * [j_state_lock]. 918 */ 919 tid_t j_commit_sequence; 920 921 /* 922 * Sequence number of the most recent transaction wanting commit 923 * [j_state_lock] 924 */ 925 tid_t j_commit_request; 926 927 /* 928 * Journal uuid: identifies the object (filesystem, LVM volume etc) 929 * backed by this journal. This will eventually be replaced by an array 930 * of uuids, allowing us to index multiple devices within a single 931 * journal and to perform atomic updates across them. 932 */ 933 __u8 j_uuid[16]; 934 935 /* Pointer to the current commit thread for this journal */ 936 struct task_struct *j_task; 937 938 /* 939 * Maximum number of metadata buffers to allow in a single compound 940 * commit transaction 941 */ 942 int j_max_transaction_buffers; 943 944 /* 945 * What is the maximum transaction lifetime before we begin a commit? 946 */ 947 unsigned long j_commit_interval; 948 949 /* The timer used to wakeup the commit thread: */ 950 struct timer_list j_commit_timer; 951 952 /* 953 * The revoke table: maintains the list of revoked blocks in the 954 * current transaction. [j_revoke_lock] 955 */ 956 spinlock_t j_revoke_lock; 957 struct jbd2_revoke_table_s *j_revoke; 958 struct jbd2_revoke_table_s *j_revoke_table[2]; 959 960 /* 961 * array of bhs for jbd2_journal_commit_transaction 962 */ 963 struct buffer_head **j_wbuf; 964 int j_wbufsize; 965 966 /* 967 * this is the pid of hte last person to run a synchronous operation 968 * through the journal 969 */ 970 pid_t j_last_sync_writer; 971 972 /* 973 * the average amount of time in nanoseconds it takes to commit a 974 * transaction to disk. [j_state_lock] 975 */ 976 u64 j_average_commit_time; 977 978 /* 979 * minimum and maximum times that we should wait for 980 * additional filesystem operations to get batched into a 981 * synchronous handle in microseconds 982 */ 983 u32 j_min_batch_time; 984 u32 j_max_batch_time; 985 986 /* This function is called when a transaction is closed */ 987 void (*j_commit_callback)(journal_t *, 988 transaction_t *); 989 990 /* 991 * Journal statistics 992 */ 993 spinlock_t j_history_lock; 994 struct proc_dir_entry *j_proc_entry; 995 struct transaction_stats_s j_stats; 996 997 /* Failed journal commit ID */ 998 unsigned int j_failed_commit; 999 1000 /* 1001 * An opaque pointer to fs-private information. ext3 puts its 1002 * superblock pointer here 1003 */ 1004 void *j_private; 1005}; 1006 1007/* 1008 * Journal flag definitions 1009 */ 1010#define JBD2_UNMOUNT 0x001 /* Journal thread is being destroyed */ 1011#define JBD2_ABORT 0x002 /* Journaling has been aborted for errors. */ 1012#define JBD2_ACK_ERR 0x004 /* The errno in the sb has been acked */ 1013#define JBD2_FLUSHED 0x008 /* The journal superblock has been flushed */ 1014#define JBD2_LOADED 0x010 /* The journal superblock has been loaded */ 1015#define JBD2_BARRIER 0x020 /* Use IDE barriers */ 1016#define JBD2_ABORT_ON_SYNCDATA_ERR 0x040 /* Abort the journal on file 1017 * data write error in ordered 1018 * mode */ 1019 1020/* 1021 * Function declarations for the journaling transaction and buffer 1022 * management 1023 */ 1024 1025/* Filing buffers */ 1026extern void jbd2_journal_unfile_buffer(journal_t *, struct journal_head *); 1027extern void __jbd2_journal_refile_buffer(struct journal_head *); 1028extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *); 1029extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int); 1030extern void __journal_free_buffer(struct journal_head *bh); 1031extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int); 1032extern void __journal_clean_data_list(transaction_t *transaction); 1033 1034/* Log buffer allocation */ 1035extern struct journal_head * jbd2_journal_get_descriptor_buffer(journal_t *); 1036int jbd2_journal_next_log_block(journal_t *, unsigned long long *); 1037 1038/* Commit management */ 1039extern void jbd2_journal_commit_transaction(journal_t *); 1040 1041/* Checkpoint list management */ 1042int __jbd2_journal_clean_checkpoint_list(journal_t *journal); 1043int __jbd2_journal_remove_checkpoint(struct journal_head *); 1044void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *); 1045 1046 1047/* 1048 * Triggers 1049 */ 1050 1051struct jbd2_buffer_trigger_type { 1052 /* 1053 * Fired a the moment data to write to the journal are known to be 1054 * stable - so either at the moment b_frozen_data is created or just 1055 * before a buffer is written to the journal. mapped_data is a mapped 1056 * buffer that is the frozen data for commit. 1057 */ 1058 void (*t_frozen)(struct jbd2_buffer_trigger_type *type, 1059 struct buffer_head *bh, void *mapped_data, 1060 size_t size); 1061 1062 /* 1063 * Fired during journal abort for dirty buffers that will not be 1064 * committed. 1065 */ 1066 void (*t_abort)(struct jbd2_buffer_trigger_type *type, 1067 struct buffer_head *bh); 1068}; 1069 1070extern void jbd2_buffer_frozen_trigger(struct journal_head *jh, 1071 void *mapped_data, 1072 struct jbd2_buffer_trigger_type *triggers); 1073extern void jbd2_buffer_abort_trigger(struct journal_head *jh, 1074 struct jbd2_buffer_trigger_type *triggers); 1075 1076/* Buffer IO */ 1077extern int 1078jbd2_journal_write_metadata_buffer(transaction_t *transaction, 1079 struct journal_head *jh_in, 1080 struct journal_head **jh_out, 1081 unsigned long long blocknr); 1082 1083/* Transaction locking */ 1084extern void __wait_on_journal (journal_t *); 1085 1086/* 1087 * Journal locking. 1088 * 1089 * We need to lock the journal during transaction state changes so that nobody 1090 * ever tries to take a handle on the running transaction while we are in the 1091 * middle of moving it to the commit phase. j_state_lock does this. 1092 * 1093 * Note that the locking is completely interrupt unsafe. We never touch 1094 * journal structures from interrupts. 1095 */ 1096 1097static inline handle_t *journal_current_handle(void) 1098{ 1099 return current->journal_info; 1100} 1101 1102/* The journaling code user interface: 1103 * 1104 * Create and destroy handles 1105 * Register buffer modifications against the current transaction. 1106 */ 1107 1108extern handle_t *jbd2_journal_start(journal_t *, int nblocks); 1109extern handle_t *jbd2__journal_start(journal_t *, int nblocks, int gfp_mask); 1110extern int jbd2_journal_restart(handle_t *, int nblocks); 1111extern int jbd2__journal_restart(handle_t *, int nblocks, int gfp_mask); 1112extern int jbd2_journal_extend (handle_t *, int nblocks); 1113extern int jbd2_journal_get_write_access(handle_t *, struct buffer_head *); 1114extern int jbd2_journal_get_create_access (handle_t *, struct buffer_head *); 1115extern int jbd2_journal_get_undo_access(handle_t *, struct buffer_head *); 1116void jbd2_journal_set_triggers(struct buffer_head *, 1117 struct jbd2_buffer_trigger_type *type); 1118extern int jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *); 1119extern void jbd2_journal_release_buffer (handle_t *, struct buffer_head *); 1120extern int jbd2_journal_forget (handle_t *, struct buffer_head *); 1121extern void journal_sync_buffer (struct buffer_head *); 1122extern void jbd2_journal_invalidatepage(journal_t *, 1123 struct page *, unsigned long); 1124extern int jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t); 1125extern int jbd2_journal_stop(handle_t *); 1126extern int jbd2_journal_flush (journal_t *); 1127extern void jbd2_journal_lock_updates (journal_t *); 1128extern void jbd2_journal_unlock_updates (journal_t *); 1129 1130extern journal_t * jbd2_journal_init_dev(struct block_device *bdev, 1131 struct block_device *fs_dev, 1132 unsigned long long start, int len, int bsize); 1133extern journal_t * jbd2_journal_init_inode (struct inode *); 1134extern int jbd2_journal_update_format (journal_t *); 1135extern int jbd2_journal_check_used_features 1136 (journal_t *, unsigned long, unsigned long, unsigned long); 1137extern int jbd2_journal_check_available_features 1138 (journal_t *, unsigned long, unsigned long, unsigned long); 1139extern int jbd2_journal_set_features 1140 (journal_t *, unsigned long, unsigned long, unsigned long); 1141extern void jbd2_journal_clear_features 1142 (journal_t *, unsigned long, unsigned long, unsigned long); 1143extern int jbd2_journal_load (journal_t *journal); 1144extern int jbd2_journal_destroy (journal_t *); 1145extern int jbd2_journal_recover (journal_t *journal); 1146extern int jbd2_journal_wipe (journal_t *, int); 1147extern int jbd2_journal_skip_recovery (journal_t *); 1148extern void jbd2_journal_update_superblock (journal_t *, int); 1149extern void __jbd2_journal_abort_hard (journal_t *); 1150extern void jbd2_journal_abort (journal_t *, int); 1151extern int jbd2_journal_errno (journal_t *); 1152extern void jbd2_journal_ack_err (journal_t *); 1153extern int jbd2_journal_clear_err (journal_t *); 1154extern int jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *); 1155extern int jbd2_journal_force_commit(journal_t *); 1156extern int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *inode); 1157extern int jbd2_journal_begin_ordered_truncate(journal_t *journal, 1158 struct jbd2_inode *inode, loff_t new_size); 1159extern void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode); 1160extern void jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode); 1161 1162/* 1163 * journal_head management 1164 */ 1165struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh); 1166struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh); 1167void jbd2_journal_put_journal_head(struct journal_head *jh); 1168 1169/* 1170 * handle management 1171 */ 1172extern struct kmem_cache *jbd2_handle_cache; 1173 1174static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags) 1175{ 1176 return kmem_cache_alloc(jbd2_handle_cache, gfp_flags); 1177} 1178 1179static inline void jbd2_free_handle(handle_t *handle) 1180{ 1181 kmem_cache_free(jbd2_handle_cache, handle); 1182} 1183 1184/* 1185 * jbd2_inode management (optional, for those file systems that want to use 1186 * dynamically allocated jbd2_inode structures) 1187 */ 1188extern struct kmem_cache *jbd2_inode_cache; 1189 1190static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags) 1191{ 1192 return kmem_cache_alloc(jbd2_inode_cache, gfp_flags); 1193} 1194 1195static inline void jbd2_free_inode(struct jbd2_inode *jinode) 1196{ 1197 kmem_cache_free(jbd2_inode_cache, jinode); 1198} 1199 1200/* Primary revoke support */ 1201#define JOURNAL_REVOKE_DEFAULT_HASH 256 1202extern int jbd2_journal_init_revoke(journal_t *, int); 1203extern void jbd2_journal_destroy_revoke_caches(void); 1204extern int jbd2_journal_init_revoke_caches(void); 1205 1206extern void jbd2_journal_destroy_revoke(journal_t *); 1207extern int jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *); 1208extern int jbd2_journal_cancel_revoke(handle_t *, struct journal_head *); 1209extern void jbd2_journal_write_revoke_records(journal_t *, 1210 transaction_t *, int); 1211 1212/* Recovery revoke support */ 1213extern int jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t); 1214extern int jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t); 1215extern void jbd2_journal_clear_revoke(journal_t *); 1216extern void jbd2_journal_switch_revoke_table(journal_t *journal); 1217 1218/* 1219 * The log thread user interface: 1220 * 1221 * Request space in the current transaction, and force transaction commit 1222 * transitions on demand. 1223 */ 1224 1225int __jbd2_log_space_left(journal_t *); /* Called with journal locked */ 1226int jbd2_log_start_commit(journal_t *journal, tid_t tid); 1227int __jbd2_log_start_commit(journal_t *journal, tid_t tid); 1228int jbd2_journal_start_commit(journal_t *journal, tid_t *tid); 1229int jbd2_journal_force_commit_nested(journal_t *journal); 1230int jbd2_log_wait_commit(journal_t *journal, tid_t tid); 1231int jbd2_log_do_checkpoint(journal_t *journal); 1232int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid); 1233 1234void __jbd2_log_wait_for_space(journal_t *journal); 1235extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *); 1236extern int jbd2_cleanup_journal_tail(journal_t *); 1237 1238/* Debugging code only: */ 1239 1240#define jbd_ENOSYS() \ 1241do { \ 1242 printk (KERN_ERR "JBD unimplemented function %s\n", __func__); \ 1243 current->state = TASK_UNINTERRUPTIBLE; \ 1244 schedule(); \ 1245} while (1) 1246 1247/* 1248 * is_journal_abort 1249 * 1250 * Simple test wrapper function to test the JBD2_ABORT state flag. This 1251 * bit, when set, indicates that we have had a fatal error somewhere, 1252 * either inside the journaling layer or indicated to us by the client 1253 * (eg. ext3), and that we and should not commit any further 1254 * transactions. 1255 */ 1256 1257static inline int is_journal_aborted(journal_t *journal) 1258{ 1259 return journal->j_flags & JBD2_ABORT; 1260} 1261 1262static inline int is_handle_aborted(handle_t *handle) 1263{ 1264 if (handle->h_aborted) 1265 return 1; 1266 return is_journal_aborted(handle->h_transaction->t_journal); 1267} 1268 1269static inline void jbd2_journal_abort_handle(handle_t *handle) 1270{ 1271 handle->h_aborted = 1; 1272} 1273 1274#endif /* __KERNEL__ */ 1275 1276/* Comparison functions for transaction IDs: perform comparisons using 1277 * modulo arithmetic so that they work over sequence number wraps. */ 1278 1279static inline int tid_gt(tid_t x, tid_t y) 1280{ 1281 int difference = (x - y); 1282 return (difference > 0); 1283} 1284 1285static inline int tid_geq(tid_t x, tid_t y) 1286{ 1287 int difference = (x - y); 1288 return (difference >= 0); 1289} 1290 1291extern int jbd2_journal_blocks_per_page(struct inode *inode); 1292extern size_t journal_tag_bytes(journal_t *journal); 1293 1294/* 1295 * Return the minimum number of blocks which must be free in the journal 1296 * before a new transaction may be started. Must be called under j_state_lock. 1297 */ 1298static inline int jbd_space_needed(journal_t *journal) 1299{ 1300 int nblocks = journal->j_max_transaction_buffers; 1301 if (journal->j_committing_transaction) 1302 nblocks += atomic_read(&journal->j_committing_transaction-> 1303 t_outstanding_credits); 1304 return nblocks; 1305} 1306 1307/* 1308 * Definitions which augment the buffer_head layer 1309 */ 1310 1311/* journaling buffer types */ 1312#define BJ_None 0 /* Not journaled */ 1313#define BJ_Metadata 1 /* Normal journaled metadata */ 1314#define BJ_Forget 2 /* Buffer superseded by this transaction */ 1315#define BJ_IO 3 /* Buffer is for temporary IO use */ 1316#define BJ_Shadow 4 /* Buffer contents being shadowed to the log */ 1317#define BJ_LogCtl 5 /* Buffer contains log descriptors */ 1318#define BJ_Reserved 6 /* Buffer is reserved for access by journal */ 1319#define BJ_Types 7 1320 1321extern int jbd_blocks_per_page(struct inode *inode); 1322 1323#ifdef __KERNEL__ 1324 1325#define buffer_trace_init(bh) do {} while (0) 1326#define print_buffer_fields(bh) do {} while (0) 1327#define print_buffer_trace(bh) do {} while (0) 1328#define BUFFER_TRACE(bh, info) do {} while (0) 1329#define BUFFER_TRACE2(bh, bh2, info) do {} while (0) 1330#define JBUFFER_TRACE(jh, info) do {} while (0) 1331 1332/* 1333 * jbd2_dev_to_name is a utility function used by the jbd2 and ext4 1334 * tracing infrastructure to map a dev_t to a device name. 1335 */ 1336extern const char *jbd2_dev_to_name(dev_t device); 1337 1338#endif /* __KERNEL__ */ 1339 1340#endif /* _LINUX_JBD2_H */ 1341