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Linux/include/linux/jbd.h

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

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