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TOMOYO Linux Cross Reference
Linux/include/linux/jbd2.h

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  1 /*
  2  * linux/include/linux/jbd2.h
  3  *
  4  * Written by Stephen C. Tweedie <sct@redhat.com>
  5  *
  6  * Copyright 1998-2000 Red Hat, Inc --- All Rights Reserved
  7  *
  8  * This file is part of the Linux kernel and is made available under
  9  * the terms of the GNU General Public License, version 2, or at your
 10  * option, any later version, incorporated herein by reference.
 11  *
 12  * Definitions for transaction data structures for the buffer cache
 13  * filesystem journaling support.
 14  */
 15 
 16 #ifndef _LINUX_JBD2_H
 17 #define _LINUX_JBD2_H
 18 
 19 /* Allow this file to be included directly into e2fsprogs */
 20 #ifndef __KERNEL__
 21 #include "jfs_compat.h"
 22 #define JBD2_DEBUG
 23 #else
 24 
 25 #include <linux/types.h>
 26 #include <linux/buffer_head.h>
 27 #include <linux/journal-head.h>
 28 #include <linux/stddef.h>
 29 #include <linux/bit_spinlock.h>
 30 #include <linux/mutex.h>
 31 #include <linux/timer.h>
 32 #include <linux/slab.h>
 33 #include <crypto/hash.h>
 34 #endif
 35 
 36 #define journal_oom_retry 1
 37 
 38 /*
 39  * Define JBD2_PARANIOD_IOFAIL to cause a kernel BUG() if ext4 finds
 40  * certain classes of error which can occur due to failed IOs.  Under
 41  * normal use we want ext4 to continue after such errors, because
 42  * hardware _can_ fail, but for debugging purposes when running tests on
 43  * known-good hardware we may want to trap these errors.
 44  */
 45 #undef JBD2_PARANOID_IOFAIL
 46 
 47 /*
 48  * The default maximum commit age, in seconds.
 49  */
 50 #define JBD2_DEFAULT_MAX_COMMIT_AGE 5
 51 
 52 #ifdef CONFIG_JBD2_DEBUG
 53 /*
 54  * Define JBD2_EXPENSIVE_CHECKING to enable more expensive internal
 55  * consistency checks.  By default we don't do this unless
 56  * CONFIG_JBD2_DEBUG is on.
 57  */
 58 #define JBD2_EXPENSIVE_CHECKING
 59 extern ushort jbd2_journal_enable_debug;
 60 
 61 #define jbd_debug(n, f, a...)                                           \
 62         do {                                                            \
 63                 if ((n) <= jbd2_journal_enable_debug) {                 \
 64                         printk (KERN_DEBUG "(%s, %d): %s: ",            \
 65                                 __FILE__, __LINE__, __func__);  \
 66                         printk (f, ## a);                               \
 67                 }                                                       \
 68         } while (0)
 69 #else
 70 #define jbd_debug(f, a...)      /**/
 71 #endif
 72 
 73 extern void *jbd2_alloc(size_t size, gfp_t flags);
 74 extern 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  **/
 97 typedef 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  **/
111 typedef 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  */
137 typedef struct journal_header_s
138 {
139         __be32          h_magic;
140         __be32          h_blocktype;
141         __be32          h_sequence;
142 } journal_header_t;
143 
144 /*
145  * Checksum types.
146  */
147 #define JBD2_CRC32_CHKSUM   1
148 #define JBD2_MD5_CHKSUM     2
149 #define JBD2_SHA1_CHKSUM    3
150 #define JBD2_CRC32C_CHKSUM  4
151 
152 #define JBD2_CRC32_CHKSUM_SIZE 4
153 
154 #define JBD2_CHECKSUM_BYTES (32 / sizeof(u32))
155 /*
156  * Commit block header for storing transactional checksums:
157  *
158  * NOTE: If FEATURE_COMPAT_CHECKSUM (checksum v1) is set, the h_chksum*
159  * fields are used to store a checksum of the descriptor and data blocks.
160  *
161  * If FEATURE_INCOMPAT_CSUM_V2 (checksum v2) is set, then the h_chksum
162  * field is used to store crc32c(uuid+commit_block).  Each journal metadata
163  * block gets its own checksum, and data block checksums are stored in
164  * journal_block_tag (in the descriptor).  The other h_chksum* fields are
165  * not used.
166  *
167  * Checksum v1 and v2 are mutually exclusive features.
168  */
169 struct commit_header {
170         __be32          h_magic;
171         __be32          h_blocktype;
172         __be32          h_sequence;
173         unsigned char   h_chksum_type;
174         unsigned char   h_chksum_size;
175         unsigned char   h_padding[2];
176         __be32          h_chksum[JBD2_CHECKSUM_BYTES];
177         __be64          h_commit_sec;
178         __be32          h_commit_nsec;
179 };
180 
181 /*
182  * The block tag: used to describe a single buffer in the journal.
183  * t_blocknr_high is only used if INCOMPAT_64BIT is set, so this
184  * raw struct shouldn't be used for pointer math or sizeof() - use
185  * journal_tag_bytes(journal) instead to compute this.
186  */
187 typedef struct journal_block_tag_s
188 {
189         __be32          t_blocknr;      /* The on-disk block number */
190         __be16          t_checksum;     /* truncated crc32c(uuid+seq+block) */
191         __be16          t_flags;        /* See below */
192         __be32          t_blocknr_high; /* most-significant high 32bits. */
193 } journal_block_tag_t;
194 
195 #define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))
196 #define JBD2_TAG_SIZE64 (sizeof(journal_block_tag_t))
197 
198 /* Tail of descriptor block, for checksumming */
199 struct jbd2_journal_block_tail {
200         __be32          t_checksum;     /* crc32c(uuid+descr_block) */
201 };
202 
203 /*
204  * The revoke descriptor: used on disk to describe a series of blocks to
205  * be revoked from the log
206  */
207 typedef struct jbd2_journal_revoke_header_s
208 {
209         journal_header_t r_header;
210         __be32           r_count;       /* Count of bytes used in the block */
211 } jbd2_journal_revoke_header_t;
212 
213 /* Tail of revoke block, for checksumming */
214 struct jbd2_journal_revoke_tail {
215         __be32          r_checksum;     /* crc32c(uuid+revoke_block) */
216 };
217 
218 /* Definitions for the journal tag flags word: */
219 #define JBD2_FLAG_ESCAPE                1       /* on-disk block is escaped */
220 #define JBD2_FLAG_SAME_UUID     2       /* block has same uuid as previous */
221 #define JBD2_FLAG_DELETED       4       /* block deleted by this transaction */
222 #define JBD2_FLAG_LAST_TAG      8       /* last tag in this descriptor block */
223 
224 
225 /*
226  * The journal superblock.  All fields are in big-endian byte order.
227  */
228 typedef struct journal_superblock_s
229 {
230 /* 0x0000 */
231         journal_header_t s_header;
232 
233 /* 0x000C */
234         /* Static information describing the journal */
235         __be32  s_blocksize;            /* journal device blocksize */
236         __be32  s_maxlen;               /* total blocks in journal file */
237         __be32  s_first;                /* first block of log information */
238 
239 /* 0x0018 */
240         /* Dynamic information describing the current state of the log */
241         __be32  s_sequence;             /* first commit ID expected in log */
242         __be32  s_start;                /* blocknr of start of log */
243 
244 /* 0x0020 */
245         /* Error value, as set by jbd2_journal_abort(). */
246         __be32  s_errno;
247 
248 /* 0x0024 */
249         /* Remaining fields are only valid in a version-2 superblock */
250         __be32  s_feature_compat;       /* compatible feature set */
251         __be32  s_feature_incompat;     /* incompatible feature set */
252         __be32  s_feature_ro_compat;    /* readonly-compatible feature set */
253 /* 0x0030 */
254         __u8    s_uuid[16];             /* 128-bit uuid for journal */
255 
256 /* 0x0040 */
257         __be32  s_nr_users;             /* Nr of filesystems sharing log */
258 
259         __be32  s_dynsuper;             /* Blocknr of dynamic superblock copy*/
260 
261 /* 0x0048 */
262         __be32  s_max_transaction;      /* Limit of journal blocks per trans.*/
263         __be32  s_max_trans_data;       /* Limit of data blocks per trans. */
264 
265 /* 0x0050 */
266         __u8    s_checksum_type;        /* checksum type */
267         __u8    s_padding2[3];
268         __u32   s_padding[42];
269         __be32  s_checksum;             /* crc32c(superblock) */
270 
271 /* 0x0100 */
272         __u8    s_users[16*48];         /* ids of all fs'es sharing the log */
273 /* 0x0400 */
274 } journal_superblock_t;
275 
276 #define JBD2_HAS_COMPAT_FEATURE(j,mask)                                 \
277         ((j)->j_format_version >= 2 &&                                  \
278          ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
279 #define JBD2_HAS_RO_COMPAT_FEATURE(j,mask)                              \
280         ((j)->j_format_version >= 2 &&                                  \
281          ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
282 #define JBD2_HAS_INCOMPAT_FEATURE(j,mask)                               \
283         ((j)->j_format_version >= 2 &&                                  \
284          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
285 
286 #define JBD2_FEATURE_COMPAT_CHECKSUM    0x00000001
287 
288 #define JBD2_FEATURE_INCOMPAT_REVOKE            0x00000001
289 #define JBD2_FEATURE_INCOMPAT_64BIT             0x00000002
290 #define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT      0x00000004
291 #define JBD2_FEATURE_INCOMPAT_CSUM_V2           0x00000008
292 
293 /* Features known to this kernel version: */
294 #define JBD2_KNOWN_COMPAT_FEATURES      JBD2_FEATURE_COMPAT_CHECKSUM
295 #define JBD2_KNOWN_ROCOMPAT_FEATURES    0
296 #define JBD2_KNOWN_INCOMPAT_FEATURES    (JBD2_FEATURE_INCOMPAT_REVOKE | \
297                                         JBD2_FEATURE_INCOMPAT_64BIT | \
298                                         JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT | \
299                                         JBD2_FEATURE_INCOMPAT_CSUM_V2)
300 
301 #ifdef __KERNEL__
302 
303 #include <linux/fs.h>
304 #include <linux/sched.h>
305 #include <linux/jbd_common.h>
306 
307 #define J_ASSERT(assert)        BUG_ON(!(assert))
308 
309 #define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
310 #define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
311 
312 #if defined(JBD2_PARANOID_IOFAIL)
313 #define J_EXPECT(expr, why...)          J_ASSERT(expr)
314 #define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
315 #define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
316 #else
317 #define __journal_expect(expr, why...)                                       \
318         ({                                                                   \
319                 int val = (expr);                                            \
320                 if (!val) {                                                  \
321                         printk(KERN_ERR                                      \
322                                "JBD2 unexpected failure: %s: %s;\n",         \
323                                __func__, #expr);                             \
324                         printk(KERN_ERR why "\n");                           \
325                 }                                                            \
326                 val;                                                         \
327         })
328 #define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)
329 #define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)
330 #define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)
331 #endif
332 
333 /* Flags in jbd_inode->i_flags */
334 #define __JI_COMMIT_RUNNING 0
335 /* Commit of the inode data in progress. We use this flag to protect us from
336  * concurrent deletion of inode. We cannot use reference to inode for this
337  * since we cannot afford doing last iput() on behalf of kjournald
338  */
339 #define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING)
340 
341 /**
342  * struct jbd_inode is the structure linking inodes in ordered mode
343  *   present in a transaction so that we can sync them during commit.
344  */
345 struct jbd2_inode {
346         /* Which transaction does this inode belong to? Either the running
347          * transaction or the committing one. [j_list_lock] */
348         transaction_t *i_transaction;
349 
350         /* Pointer to the running transaction modifying inode's data in case
351          * there is already a committing transaction touching it. [j_list_lock] */
352         transaction_t *i_next_transaction;
353 
354         /* List of inodes in the i_transaction [j_list_lock] */
355         struct list_head i_list;
356 
357         /* VFS inode this inode belongs to [constant during the lifetime
358          * of the structure] */
359         struct inode *i_vfs_inode;
360 
361         /* Flags of inode [j_list_lock] */
362         unsigned long i_flags;
363 };
364 
365 struct jbd2_revoke_table_s;
366 
367 /**
368  * struct handle_s - The handle_s type is the concrete type associated with
369  *     handle_t.
370  * @h_transaction: Which compound transaction is this update a part of?
371  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
372  * @h_ref: Reference count on this handle
373  * @h_err: Field for caller's use to track errors through large fs operations
374  * @h_sync: flag for sync-on-close
375  * @h_jdata: flag to force data journaling
376  * @h_aborted: flag indicating fatal error on handle
377  **/
378 
379 /* Docbook can't yet cope with the bit fields, but will leave the documentation
380  * in so it can be fixed later.
381  */
382 
383 struct jbd2_journal_handle
384 {
385         /* Which compound transaction is this update a part of? */
386         transaction_t           *h_transaction;
387 
388         /* Number of remaining buffers we are allowed to dirty: */
389         int                     h_buffer_credits;
390 
391         /* Reference count on this handle */
392         int                     h_ref;
393 
394         /* Field for caller's use to track errors through large fs */
395         /* operations */
396         int                     h_err;
397 
398         /* Flags [no locking] */
399         unsigned int    h_sync:         1;      /* sync-on-close */
400         unsigned int    h_jdata:        1;      /* force data journaling */
401         unsigned int    h_aborted:      1;      /* fatal error on handle */
402         unsigned int    h_type:         8;      /* for handle statistics */
403         unsigned int    h_line_no:      16;     /* for handle statistics */
404 
405         unsigned long           h_start_jiffies;
406         unsigned int            h_requested_credits;
407 
408 #ifdef CONFIG_DEBUG_LOCK_ALLOC
409         struct lockdep_map      h_lockdep_map;
410 #endif
411 };
412 
413 
414 /*
415  * Some stats for checkpoint phase
416  */
417 struct transaction_chp_stats_s {
418         unsigned long           cs_chp_time;
419         __u32                   cs_forced_to_close;
420         __u32                   cs_written;
421         __u32                   cs_dropped;
422 };
423 
424 /* The transaction_t type is the guts of the journaling mechanism.  It
425  * tracks a compound transaction through its various states:
426  *
427  * RUNNING:     accepting new updates
428  * LOCKED:      Updates still running but we don't accept new ones
429  * RUNDOWN:     Updates are tidying up but have finished requesting
430  *              new buffers to modify (state not used for now)
431  * FLUSH:       All updates complete, but we are still writing to disk
432  * COMMIT:      All data on disk, writing commit record
433  * FINISHED:    We still have to keep the transaction for checkpointing.
434  *
435  * The transaction keeps track of all of the buffers modified by a
436  * running transaction, and all of the buffers committed but not yet
437  * flushed to home for finished transactions.
438  */
439 
440 /*
441  * Lock ranking:
442  *
443  *    j_list_lock
444  *      ->jbd_lock_bh_journal_head()    (This is "innermost")
445  *
446  *    j_state_lock
447  *    ->jbd_lock_bh_state()
448  *
449  *    jbd_lock_bh_state()
450  *    ->j_list_lock
451  *
452  *    j_state_lock
453  *    ->t_handle_lock
454  *
455  *    j_state_lock
456  *    ->j_list_lock                     (journal_unmap_buffer)
457  *
458  */
459 
460 struct transaction_s
461 {
462         /* Pointer to the journal for this transaction. [no locking] */
463         journal_t               *t_journal;
464 
465         /* Sequence number for this transaction [no locking] */
466         tid_t                   t_tid;
467 
468         /*
469          * Transaction's current state
470          * [no locking - only kjournald2 alters this]
471          * [j_list_lock] guards transition of a transaction into T_FINISHED
472          * state and subsequent call of __jbd2_journal_drop_transaction()
473          * FIXME: needs barriers
474          * KLUDGE: [use j_state_lock]
475          */
476         enum {
477                 T_RUNNING,
478                 T_LOCKED,
479                 T_FLUSH,
480                 T_COMMIT,
481                 T_COMMIT_DFLUSH,
482                 T_COMMIT_JFLUSH,
483                 T_COMMIT_CALLBACK,
484                 T_FINISHED
485         }                       t_state;
486 
487         /*
488          * Where in the log does this transaction's commit start? [no locking]
489          */
490         unsigned long           t_log_start;
491 
492         /* Number of buffers on the t_buffers list [j_list_lock] */
493         int                     t_nr_buffers;
494 
495         /*
496          * Doubly-linked circular list of all buffers reserved but not yet
497          * modified by this transaction [j_list_lock]
498          */
499         struct journal_head     *t_reserved_list;
500 
501         /*
502          * Doubly-linked circular list of all metadata buffers owned by this
503          * transaction [j_list_lock]
504          */
505         struct journal_head     *t_buffers;
506 
507         /*
508          * Doubly-linked circular list of all forget buffers (superseded
509          * buffers which we can un-checkpoint once this transaction commits)
510          * [j_list_lock]
511          */
512         struct journal_head     *t_forget;
513 
514         /*
515          * Doubly-linked circular list of all buffers still to be flushed before
516          * this transaction can be checkpointed. [j_list_lock]
517          */
518         struct journal_head     *t_checkpoint_list;
519 
520         /*
521          * Doubly-linked circular list of all buffers submitted for IO while
522          * checkpointing. [j_list_lock]
523          */
524         struct journal_head     *t_checkpoint_io_list;
525 
526         /*
527          * Doubly-linked circular list of temporary buffers currently undergoing
528          * IO in the log [j_list_lock]
529          */
530         struct journal_head     *t_iobuf_list;
531 
532         /*
533          * Doubly-linked circular list of metadata buffers being shadowed by log
534          * IO.  The IO buffers on the iobuf list and the shadow buffers on this
535          * list match each other one for one at all times. [j_list_lock]
536          */
537         struct journal_head     *t_shadow_list;
538 
539         /*
540          * Doubly-linked circular list of control buffers being written to the
541          * log. [j_list_lock]
542          */
543         struct journal_head     *t_log_list;
544 
545         /*
546          * List of inodes whose data we've modified in data=ordered mode.
547          * [j_list_lock]
548          */
549         struct list_head        t_inode_list;
550 
551         /*
552          * Protects info related to handles
553          */
554         spinlock_t              t_handle_lock;
555 
556         /*
557          * Longest time some handle had to wait for running transaction
558          */
559         unsigned long           t_max_wait;
560 
561         /*
562          * When transaction started
563          */
564         unsigned long           t_start;
565 
566         /*
567          * When commit was requested
568          */
569         unsigned long           t_requested;
570 
571         /*
572          * Checkpointing stats [j_checkpoint_sem]
573          */
574         struct transaction_chp_stats_s t_chp_stats;
575 
576         /*
577          * Number of outstanding updates running on this transaction
578          * [t_handle_lock]
579          */
580         atomic_t                t_updates;
581 
582         /*
583          * Number of buffers reserved for use by all handles in this transaction
584          * handle but not yet modified. [t_handle_lock]
585          */
586         atomic_t                t_outstanding_credits;
587 
588         /*
589          * Forward and backward links for the circular list of all transactions
590          * awaiting checkpoint. [j_list_lock]
591          */
592         transaction_t           *t_cpnext, *t_cpprev;
593 
594         /*
595          * When will the transaction expire (become due for commit), in jiffies?
596          * [no locking]
597          */
598         unsigned long           t_expires;
599 
600         /*
601          * When this transaction started, in nanoseconds [no locking]
602          */
603         ktime_t                 t_start_time;
604 
605         /*
606          * How many handles used this transaction? [t_handle_lock]
607          */
608         atomic_t                t_handle_count;
609 
610         /*
611          * This transaction is being forced and some process is
612          * waiting for it to finish.
613          */
614         unsigned int t_synchronous_commit:1;
615 
616         /* Disk flush needs to be sent to fs partition [no locking] */
617         int                     t_need_data_flush;
618 
619         /*
620          * For use by the filesystem to store fs-specific data
621          * structures associated with the transaction
622          */
623         struct list_head        t_private_list;
624 };
625 
626 struct transaction_run_stats_s {
627         unsigned long           rs_wait;
628         unsigned long           rs_request_delay;
629         unsigned long           rs_running;
630         unsigned long           rs_locked;
631         unsigned long           rs_flushing;
632         unsigned long           rs_logging;
633 
634         __u32                   rs_handle_count;
635         __u32                   rs_blocks;
636         __u32                   rs_blocks_logged;
637 };
638 
639 struct transaction_stats_s {
640         unsigned long           ts_tid;
641         unsigned long           ts_requested;
642         struct transaction_run_stats_s run;
643 };
644 
645 static inline unsigned long
646 jbd2_time_diff(unsigned long start, unsigned long end)
647 {
648         if (end >= start)
649                 return end - start;
650 
651         return end + (MAX_JIFFY_OFFSET - start);
652 }
653 
654 #define JBD2_NR_BATCH   64
655 
656 /**
657  * struct journal_s - The journal_s type is the concrete type associated with
658  *     journal_t.
659  * @j_flags:  General journaling state flags
660  * @j_errno:  Is there an outstanding uncleared error on the journal (from a
661  *     prior abort)?
662  * @j_sb_buffer: First part of superblock buffer
663  * @j_superblock: Second part of superblock buffer
664  * @j_format_version: Version of the superblock format
665  * @j_state_lock: Protect the various scalars in the journal
666  * @j_barrier_count:  Number of processes waiting to create a barrier lock
667  * @j_barrier: The barrier lock itself
668  * @j_running_transaction: The current running transaction..
669  * @j_committing_transaction: the transaction we are pushing to disk
670  * @j_checkpoint_transactions: a linked circular list of all transactions
671  *  waiting for checkpointing
672  * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
673  *  to start committing, or for a barrier lock to be released
674  * @j_wait_logspace: Wait queue for waiting for checkpointing to complete
675  * @j_wait_done_commit: Wait queue for waiting for commit to complete
676  * @j_wait_checkpoint:  Wait queue to trigger checkpointing
677  * @j_wait_commit: Wait queue to trigger commit
678  * @j_wait_updates: Wait queue to wait for updates to complete
679  * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
680  * @j_head: Journal head - identifies the first unused block in the journal
681  * @j_tail: Journal tail - identifies the oldest still-used block in the
682  *  journal.
683  * @j_free: Journal free - how many free blocks are there in the journal?
684  * @j_first: The block number of the first usable block
685  * @j_last: The block number one beyond the last usable block
686  * @j_dev: Device where we store the journal
687  * @j_blocksize: blocksize for the location where we store the journal.
688  * @j_blk_offset: starting block offset for into the device where we store the
689  *     journal
690  * @j_fs_dev: Device which holds the client fs.  For internal journal this will
691  *     be equal to j_dev
692  * @j_maxlen: Total maximum capacity of the journal region on disk.
693  * @j_list_lock: Protects the buffer lists and internal buffer state.
694  * @j_inode: Optional inode where we store the journal.  If present, all journal
695  *     block numbers are mapped into this inode via bmap().
696  * @j_tail_sequence:  Sequence number of the oldest transaction in the log
697  * @j_transaction_sequence: Sequence number of the next transaction to grant
698  * @j_commit_sequence: Sequence number of the most recently committed
699  *  transaction
700  * @j_commit_request: Sequence number of the most recent transaction wanting
701  *     commit
702  * @j_uuid: Uuid of client object.
703  * @j_task: Pointer to the current commit thread for this journal
704  * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
705  *     single compound commit transaction
706  * @j_commit_interval: What is the maximum transaction lifetime before we begin
707  *  a commit?
708  * @j_commit_timer:  The timer used to wakeup the commit thread
709  * @j_revoke_lock: Protect the revoke table
710  * @j_revoke: The revoke table - maintains the list of revoked blocks in the
711  *     current transaction.
712  * @j_revoke_table: alternate revoke tables for j_revoke
713  * @j_wbuf: array of buffer_heads for jbd2_journal_commit_transaction
714  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
715  *      number that will fit in j_blocksize
716  * @j_last_sync_writer: most recent pid which did a synchronous write
717  * @j_history: Buffer storing the transactions statistics history
718  * @j_history_max: Maximum number of transactions in the statistics history
719  * @j_history_cur: Current number of transactions in the statistics history
720  * @j_history_lock: Protect the transactions statistics history
721  * @j_proc_entry: procfs entry for the jbd statistics directory
722  * @j_stats: Overall statistics
723  * @j_private: An opaque pointer to fs-private information.
724  */
725 
726 struct journal_s
727 {
728         /* General journaling state flags [j_state_lock] */
729         unsigned long           j_flags;
730 
731         /*
732          * Is there an outstanding uncleared error on the journal (from a prior
733          * abort)? [j_state_lock]
734          */
735         int                     j_errno;
736 
737         /* The superblock buffer */
738         struct buffer_head      *j_sb_buffer;
739         journal_superblock_t    *j_superblock;
740 
741         /* Version of the superblock format */
742         int                     j_format_version;
743 
744         /*
745          * Protect the various scalars in the journal
746          */
747         rwlock_t                j_state_lock;
748 
749         /*
750          * Number of processes waiting to create a barrier lock [j_state_lock]
751          */
752         int                     j_barrier_count;
753 
754         /* The barrier lock itself */
755         struct mutex            j_barrier;
756 
757         /*
758          * Transactions: The current running transaction...
759          * [j_state_lock] [caller holding open handle]
760          */
761         transaction_t           *j_running_transaction;
762 
763         /*
764          * the transaction we are pushing to disk
765          * [j_state_lock] [caller holding open handle]
766          */
767         transaction_t           *j_committing_transaction;
768 
769         /*
770          * ... and a linked circular list of all transactions waiting for
771          * checkpointing. [j_list_lock]
772          */
773         transaction_t           *j_checkpoint_transactions;
774 
775         /*
776          * Wait queue for waiting for a locked transaction to start committing,
777          * or for a barrier lock to be released
778          */
779         wait_queue_head_t       j_wait_transaction_locked;
780 
781         /* Wait queue for waiting for checkpointing to complete */
782         wait_queue_head_t       j_wait_logspace;
783 
784         /* Wait queue for waiting for commit to complete */
785         wait_queue_head_t       j_wait_done_commit;
786 
787         /* Wait queue to trigger checkpointing */
788         wait_queue_head_t       j_wait_checkpoint;
789 
790         /* Wait queue to trigger commit */
791         wait_queue_head_t       j_wait_commit;
792 
793         /* Wait queue to wait for updates to complete */
794         wait_queue_head_t       j_wait_updates;
795 
796         /* Semaphore for locking against concurrent checkpoints */
797         struct mutex            j_checkpoint_mutex;
798 
799         /*
800          * List of buffer heads used by the checkpoint routine.  This
801          * was moved from jbd2_log_do_checkpoint() to reduce stack
802          * usage.  Access to this array is controlled by the
803          * j_checkpoint_mutex.  [j_checkpoint_mutex]
804          */
805         struct buffer_head      *j_chkpt_bhs[JBD2_NR_BATCH];
806         
807         /*
808          * Journal head: identifies the first unused block in the journal.
809          * [j_state_lock]
810          */
811         unsigned long           j_head;
812 
813         /*
814          * Journal tail: identifies the oldest still-used block in the journal.
815          * [j_state_lock]
816          */
817         unsigned long           j_tail;
818 
819         /*
820          * Journal free: how many free blocks are there in the journal?
821          * [j_state_lock]
822          */
823         unsigned long           j_free;
824 
825         /*
826          * Journal start and end: the block numbers of the first usable block
827          * and one beyond the last usable block in the journal. [j_state_lock]
828          */
829         unsigned long           j_first;
830         unsigned long           j_last;
831 
832         /*
833          * Device, blocksize and starting block offset for the location where we
834          * store the journal.
835          */
836         struct block_device     *j_dev;
837         int                     j_blocksize;
838         unsigned long long      j_blk_offset;
839         char                    j_devname[BDEVNAME_SIZE+24];
840 
841         /*
842          * Device which holds the client fs.  For internal journal this will be
843          * equal to j_dev.
844          */
845         struct block_device     *j_fs_dev;
846 
847         /* Total maximum capacity of the journal region on disk. */
848         unsigned int            j_maxlen;
849 
850         /*
851          * Protects the buffer lists and internal buffer state.
852          */
853         spinlock_t              j_list_lock;
854 
855         /* Optional inode where we store the journal.  If present, all */
856         /* journal block numbers are mapped into this inode via */
857         /* bmap(). */
858         struct inode            *j_inode;
859 
860         /*
861          * Sequence number of the oldest transaction in the log [j_state_lock]
862          */
863         tid_t                   j_tail_sequence;
864 
865         /*
866          * Sequence number of the next transaction to grant [j_state_lock]
867          */
868         tid_t                   j_transaction_sequence;
869 
870         /*
871          * Sequence number of the most recently committed transaction
872          * [j_state_lock].
873          */
874         tid_t                   j_commit_sequence;
875 
876         /*
877          * Sequence number of the most recent transaction wanting commit
878          * [j_state_lock]
879          */
880         tid_t                   j_commit_request;
881 
882         /*
883          * Journal uuid: identifies the object (filesystem, LVM volume etc)
884          * backed by this journal.  This will eventually be replaced by an array
885          * of uuids, allowing us to index multiple devices within a single
886          * journal and to perform atomic updates across them.
887          */
888         __u8                    j_uuid[16];
889 
890         /* Pointer to the current commit thread for this journal */
891         struct task_struct      *j_task;
892 
893         /*
894          * Maximum number of metadata buffers to allow in a single compound
895          * commit transaction
896          */
897         int                     j_max_transaction_buffers;
898 
899         /*
900          * What is the maximum transaction lifetime before we begin a commit?
901          */
902         unsigned long           j_commit_interval;
903 
904         /* The timer used to wakeup the commit thread: */
905         struct timer_list       j_commit_timer;
906 
907         /*
908          * The revoke table: maintains the list of revoked blocks in the
909          * current transaction.  [j_revoke_lock]
910          */
911         spinlock_t              j_revoke_lock;
912         struct jbd2_revoke_table_s *j_revoke;
913         struct jbd2_revoke_table_s *j_revoke_table[2];
914 
915         /*
916          * array of bhs for jbd2_journal_commit_transaction
917          */
918         struct buffer_head      **j_wbuf;
919         int                     j_wbufsize;
920 
921         /*
922          * this is the pid of hte last person to run a synchronous operation
923          * through the journal
924          */
925         pid_t                   j_last_sync_writer;
926 
927         /*
928          * the average amount of time in nanoseconds it takes to commit a
929          * transaction to disk. [j_state_lock]
930          */
931         u64                     j_average_commit_time;
932 
933         /*
934          * minimum and maximum times that we should wait for
935          * additional filesystem operations to get batched into a
936          * synchronous handle in microseconds
937          */
938         u32                     j_min_batch_time;
939         u32                     j_max_batch_time;
940 
941         /* This function is called when a transaction is closed */
942         void                    (*j_commit_callback)(journal_t *,
943                                                      transaction_t *);
944 
945         /*
946          * Journal statistics
947          */
948         spinlock_t              j_history_lock;
949         struct proc_dir_entry   *j_proc_entry;
950         struct transaction_stats_s j_stats;
951 
952         /* Failed journal commit ID */
953         unsigned int            j_failed_commit;
954 
955         /*
956          * An opaque pointer to fs-private information.  ext3 puts its
957          * superblock pointer here
958          */
959         void *j_private;
960 
961         /* Reference to checksum algorithm driver via cryptoapi */
962         struct crypto_shash *j_chksum_driver;
963 
964         /* Precomputed journal UUID checksum for seeding other checksums */
965         __u32 j_csum_seed;
966 };
967 
968 /*
969  * Journal flag definitions
970  */
971 #define JBD2_UNMOUNT    0x001   /* Journal thread is being destroyed */
972 #define JBD2_ABORT      0x002   /* Journaling has been aborted for errors. */
973 #define JBD2_ACK_ERR    0x004   /* The errno in the sb has been acked */
974 #define JBD2_FLUSHED    0x008   /* The journal superblock has been flushed */
975 #define JBD2_LOADED     0x010   /* The journal superblock has been loaded */
976 #define JBD2_BARRIER    0x020   /* Use IDE barriers */
977 #define JBD2_ABORT_ON_SYNCDATA_ERR      0x040   /* Abort the journal on file
978                                                  * data write error in ordered
979                                                  * mode */
980 
981 /*
982  * Function declarations for the journaling transaction and buffer
983  * management
984  */
985 
986 /* Filing buffers */
987 extern void jbd2_journal_unfile_buffer(journal_t *, struct journal_head *);
988 extern void __jbd2_journal_refile_buffer(struct journal_head *);
989 extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *);
990 extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
991 extern void __journal_free_buffer(struct journal_head *bh);
992 extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
993 extern void __journal_clean_data_list(transaction_t *transaction);
994 
995 /* Log buffer allocation */
996 extern struct journal_head * jbd2_journal_get_descriptor_buffer(journal_t *);
997 int jbd2_journal_next_log_block(journal_t *, unsigned long long *);
998 int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
999                               unsigned long *block);
1000 void __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1001 void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1002 
1003 /* Commit management */
1004 extern void jbd2_journal_commit_transaction(journal_t *);
1005 
1006 /* Checkpoint list management */
1007 int __jbd2_journal_clean_checkpoint_list(journal_t *journal);
1008 int __jbd2_journal_remove_checkpoint(struct journal_head *);
1009 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
1010 
1011 
1012 /*
1013  * Triggers
1014  */
1015 
1016 struct jbd2_buffer_trigger_type {
1017         /*
1018          * Fired a the moment data to write to the journal are known to be
1019          * stable - so either at the moment b_frozen_data is created or just
1020          * before a buffer is written to the journal.  mapped_data is a mapped
1021          * buffer that is the frozen data for commit.
1022          */
1023         void (*t_frozen)(struct jbd2_buffer_trigger_type *type,
1024                          struct buffer_head *bh, void *mapped_data,
1025                          size_t size);
1026 
1027         /*
1028          * Fired during journal abort for dirty buffers that will not be
1029          * committed.
1030          */
1031         void (*t_abort)(struct jbd2_buffer_trigger_type *type,
1032                         struct buffer_head *bh);
1033 };
1034 
1035 extern void jbd2_buffer_frozen_trigger(struct journal_head *jh,
1036                                        void *mapped_data,
1037                                        struct jbd2_buffer_trigger_type *triggers);
1038 extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
1039                                       struct jbd2_buffer_trigger_type *triggers);
1040 
1041 /* Buffer IO */
1042 extern int
1043 jbd2_journal_write_metadata_buffer(transaction_t          *transaction,
1044                               struct journal_head  *jh_in,
1045                               struct journal_head **jh_out,
1046                               unsigned long long   blocknr);
1047 
1048 /* Transaction locking */
1049 extern void             __wait_on_journal (journal_t *);
1050 
1051 /* Transaction cache support */
1052 extern void jbd2_journal_destroy_transaction_cache(void);
1053 extern int  jbd2_journal_init_transaction_cache(void);
1054 extern void jbd2_journal_free_transaction(transaction_t *);
1055 
1056 /*
1057  * Journal locking.
1058  *
1059  * We need to lock the journal during transaction state changes so that nobody
1060  * ever tries to take a handle on the running transaction while we are in the
1061  * middle of moving it to the commit phase.  j_state_lock does this.
1062  *
1063  * Note that the locking is completely interrupt unsafe.  We never touch
1064  * journal structures from interrupts.
1065  */
1066 
1067 static inline handle_t *journal_current_handle(void)
1068 {
1069         return current->journal_info;
1070 }
1071 
1072 /* The journaling code user interface:
1073  *
1074  * Create and destroy handles
1075  * Register buffer modifications against the current transaction.
1076  */
1077 
1078 extern handle_t *jbd2_journal_start(journal_t *, int nblocks);
1079 extern handle_t *jbd2__journal_start(journal_t *, int nblocks, gfp_t gfp_mask,
1080                                      unsigned int type, unsigned int line_no);
1081 extern int       jbd2_journal_restart(handle_t *, int nblocks);
1082 extern int       jbd2__journal_restart(handle_t *, int nblocks, gfp_t gfp_mask);
1083 extern int       jbd2_journal_extend (handle_t *, int nblocks);
1084 extern int       jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
1085 extern int       jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
1086 extern int       jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
1087 void             jbd2_journal_set_triggers(struct buffer_head *,
1088                                            struct jbd2_buffer_trigger_type *type);
1089 extern int       jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
1090 extern int       jbd2_journal_forget (handle_t *, struct buffer_head *);
1091 extern void      journal_sync_buffer (struct buffer_head *);
1092 extern int       jbd2_journal_invalidatepage(journal_t *,
1093                                 struct page *, unsigned long);
1094 extern int       jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
1095 extern int       jbd2_journal_stop(handle_t *);
1096 extern int       jbd2_journal_flush (journal_t *);
1097 extern void      jbd2_journal_lock_updates (journal_t *);
1098 extern void      jbd2_journal_unlock_updates (journal_t *);
1099 
1100 extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1101                                 struct block_device *fs_dev,
1102                                 unsigned long long start, int len, int bsize);
1103 extern journal_t * jbd2_journal_init_inode (struct inode *);
1104 extern int         jbd2_journal_update_format (journal_t *);
1105 extern int         jbd2_journal_check_used_features
1106                    (journal_t *, unsigned long, unsigned long, unsigned long);
1107 extern int         jbd2_journal_check_available_features
1108                    (journal_t *, unsigned long, unsigned long, unsigned long);
1109 extern int         jbd2_journal_set_features
1110                    (journal_t *, unsigned long, unsigned long, unsigned long);
1111 extern void        jbd2_journal_clear_features
1112                    (journal_t *, unsigned long, unsigned long, unsigned long);
1113 extern int         jbd2_journal_load       (journal_t *journal);
1114 extern int         jbd2_journal_destroy    (journal_t *);
1115 extern int         jbd2_journal_recover    (journal_t *journal);
1116 extern int         jbd2_journal_wipe       (journal_t *, int);
1117 extern int         jbd2_journal_skip_recovery   (journal_t *);
1118 extern void        jbd2_journal_update_sb_errno(journal_t *);
1119 extern void        jbd2_journal_update_sb_log_tail      (journal_t *, tid_t,
1120                                 unsigned long, int);
1121 extern void        __jbd2_journal_abort_hard    (journal_t *);
1122 extern void        jbd2_journal_abort      (journal_t *, int);
1123 extern int         jbd2_journal_errno      (journal_t *);
1124 extern void        jbd2_journal_ack_err    (journal_t *);
1125 extern int         jbd2_journal_clear_err  (journal_t *);
1126 extern int         jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
1127 extern int         jbd2_journal_force_commit(journal_t *);
1128 extern int         jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *inode);
1129 extern int         jbd2_journal_begin_ordered_truncate(journal_t *journal,
1130                                 struct jbd2_inode *inode, loff_t new_size);
1131 extern void        jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);
1132 extern void        jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode);
1133 
1134 /*
1135  * journal_head management
1136  */
1137 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh);
1138 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh);
1139 void jbd2_journal_put_journal_head(struct journal_head *jh);
1140 
1141 /*
1142  * handle management
1143  */
1144 extern struct kmem_cache *jbd2_handle_cache;
1145 
1146 static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags)
1147 {
1148         return kmem_cache_alloc(jbd2_handle_cache, gfp_flags);
1149 }
1150 
1151 static inline void jbd2_free_handle(handle_t *handle)
1152 {
1153         kmem_cache_free(jbd2_handle_cache, handle);
1154 }
1155 
1156 /*
1157  * jbd2_inode management (optional, for those file systems that want to use
1158  * dynamically allocated jbd2_inode structures)
1159  */
1160 extern struct kmem_cache *jbd2_inode_cache;
1161 
1162 static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags)
1163 {
1164         return kmem_cache_alloc(jbd2_inode_cache, gfp_flags);
1165 }
1166 
1167 static inline void jbd2_free_inode(struct jbd2_inode *jinode)
1168 {
1169         kmem_cache_free(jbd2_inode_cache, jinode);
1170 }
1171 
1172 /* Primary revoke support */
1173 #define JOURNAL_REVOKE_DEFAULT_HASH 256
1174 extern int         jbd2_journal_init_revoke(journal_t *, int);
1175 extern void        jbd2_journal_destroy_revoke_caches(void);
1176 extern int         jbd2_journal_init_revoke_caches(void);
1177 
1178 extern void        jbd2_journal_destroy_revoke(journal_t *);
1179 extern int         jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *);
1180 extern int         jbd2_journal_cancel_revoke(handle_t *, struct journal_head *);
1181 extern void        jbd2_journal_write_revoke_records(journal_t *,
1182                                                      transaction_t *, int);
1183 
1184 /* Recovery revoke support */
1185 extern int      jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t);
1186 extern int      jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t);
1187 extern void     jbd2_journal_clear_revoke(journal_t *);
1188 extern void     jbd2_journal_switch_revoke_table(journal_t *journal);
1189 extern void     jbd2_clear_buffer_revoked_flags(journal_t *journal);
1190 
1191 /*
1192  * The log thread user interface:
1193  *
1194  * Request space in the current transaction, and force transaction commit
1195  * transitions on demand.
1196  */
1197 
1198 int __jbd2_log_space_left(journal_t *); /* Called with journal locked */
1199 int jbd2_log_start_commit(journal_t *journal, tid_t tid);
1200 int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
1201 int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
1202 int jbd2_journal_force_commit_nested(journal_t *journal);
1203 int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
1204 int jbd2_complete_transaction(journal_t *journal, tid_t tid);
1205 int jbd2_log_do_checkpoint(journal_t *journal);
1206 int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
1207 
1208 void __jbd2_log_wait_for_space(journal_t *journal);
1209 extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
1210 extern int jbd2_cleanup_journal_tail(journal_t *);
1211 
1212 /* Debugging code only: */
1213 
1214 #define jbd_ENOSYS() \
1215 do {                                                                       \
1216         printk (KERN_ERR "JBD unimplemented function %s\n", __func__); \
1217         current->state = TASK_UNINTERRUPTIBLE;                             \
1218         schedule();                                                        \
1219 } while (1)
1220 
1221 /*
1222  * is_journal_abort
1223  *
1224  * Simple test wrapper function to test the JBD2_ABORT state flag.  This
1225  * bit, when set, indicates that we have had a fatal error somewhere,
1226  * either inside the journaling layer or indicated to us by the client
1227  * (eg. ext3), and that we and should not commit any further
1228  * transactions.
1229  */
1230 
1231 static inline int is_journal_aborted(journal_t *journal)
1232 {
1233         return journal->j_flags & JBD2_ABORT;
1234 }
1235 
1236 static inline int is_handle_aborted(handle_t *handle)
1237 {
1238         if (handle->h_aborted)
1239                 return 1;
1240         return is_journal_aborted(handle->h_transaction->t_journal);
1241 }
1242 
1243 static inline void jbd2_journal_abort_handle(handle_t *handle)
1244 {
1245         handle->h_aborted = 1;
1246 }
1247 
1248 #endif /* __KERNEL__   */
1249 
1250 /* Comparison functions for transaction IDs: perform comparisons using
1251  * modulo arithmetic so that they work over sequence number wraps. */
1252 
1253 static inline int tid_gt(tid_t x, tid_t y)
1254 {
1255         int difference = (x - y);
1256         return (difference > 0);
1257 }
1258 
1259 static inline int tid_geq(tid_t x, tid_t y)
1260 {
1261         int difference = (x - y);
1262         return (difference >= 0);
1263 }
1264 
1265 extern int jbd2_journal_blocks_per_page(struct inode *inode);
1266 extern size_t journal_tag_bytes(journal_t *journal);
1267 
1268 /*
1269  * Return the minimum number of blocks which must be free in the journal
1270  * before a new transaction may be started.  Must be called under j_state_lock.
1271  */
1272 static inline int jbd_space_needed(journal_t *journal)
1273 {
1274         int nblocks = journal->j_max_transaction_buffers;
1275         if (journal->j_committing_transaction)
1276                 nblocks += atomic_read(&journal->j_committing_transaction->
1277                                        t_outstanding_credits);
1278         return nblocks;
1279 }
1280 
1281 /*
1282  * Definitions which augment the buffer_head layer
1283  */
1284 
1285 /* journaling buffer types */
1286 #define BJ_None         0       /* Not journaled */
1287 #define BJ_Metadata     1       /* Normal journaled metadata */
1288 #define BJ_Forget       2       /* Buffer superseded by this transaction */
1289 #define BJ_IO           3       /* Buffer is for temporary IO use */
1290 #define BJ_Shadow       4       /* Buffer contents being shadowed to the log */
1291 #define BJ_LogCtl       5       /* Buffer contains log descriptors */
1292 #define BJ_Reserved     6       /* Buffer is reserved for access by journal */
1293 #define BJ_Types        7
1294 
1295 extern int jbd_blocks_per_page(struct inode *inode);
1296 
1297 /* JBD uses a CRC32 checksum */
1298 #define JBD_MAX_CHECKSUM_SIZE 4
1299 
1300 static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
1301                               const void *address, unsigned int length)
1302 {
1303         struct {
1304                 struct shash_desc shash;
1305                 char ctx[JBD_MAX_CHECKSUM_SIZE];
1306         } desc;
1307         int err;
1308 
1309         BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >
1310                 JBD_MAX_CHECKSUM_SIZE);
1311 
1312         desc.shash.tfm = journal->j_chksum_driver;
1313         desc.shash.flags = 0;
1314         *(u32 *)desc.ctx = crc;
1315 
1316         err = crypto_shash_update(&desc.shash, address, length);
1317         BUG_ON(err);
1318 
1319         return *(u32 *)desc.ctx;
1320 }
1321 
1322 #ifdef __KERNEL__
1323 
1324 #define buffer_trace_init(bh)   do {} while (0)
1325 #define print_buffer_fields(bh) do {} while (0)
1326 #define print_buffer_trace(bh)  do {} while (0)
1327 #define BUFFER_TRACE(bh, info)  do {} while (0)
1328 #define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1329 #define JBUFFER_TRACE(jh, info) do {} while (0)
1330 
1331 #endif  /* __KERNEL__ */
1332 
1333 #endif  /* _LINUX_JBD2_H */
1334 

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