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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/mutex.h>
 30 #include <linux/timer.h>
 31 #include <linux/slab.h>
 32 #include <linux/bit_spinlock.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 void __jbd2_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         __jbd2_debug((n), __FILE__, __func__, __LINE__, (fmt), ##a)
 65 #else
 66 #define jbd_debug(n, fmt, a...)    /**/
 67 #endif
 68 
 69 extern void *jbd2_alloc(size_t size, gfp_t flags);
 70 extern void jbd2_free(void *ptr, size_t size);
 71 
 72 #define JBD2_MIN_JOURNAL_BLOCKS 1024
 73 
 74 #ifdef __KERNEL__
 75 
 76 /**
 77  * typedef handle_t - The handle_t type represents a single atomic update being performed by some process.
 78  *
 79  * All filesystem modifications made by the process go
 80  * through this handle.  Recursive operations (such as quota operations)
 81  * are gathered into a single update.
 82  *
 83  * The buffer credits field is used to account for journaled buffers
 84  * being modified by the running process.  To ensure that there is
 85  * enough log space for all outstanding operations, we need to limit the
 86  * number of outstanding buffers possible at any time.  When the
 87  * operation completes, any buffer credits not used are credited back to
 88  * the transaction, so that at all times we know how many buffers the
 89  * outstanding updates on a transaction might possibly touch.
 90  *
 91  * This is an opaque datatype.
 92  **/
 93 typedef struct jbd2_journal_handle handle_t;    /* Atomic operation type */
 94 
 95 
 96 /**
 97  * typedef journal_t - The journal_t maintains all of the journaling state information for a single filesystem.
 98  *
 99  * journal_t is linked to from the fs superblock structure.
100  *
101  * We use the journal_t to keep track of all outstanding transaction
102  * activity on the filesystem, and to manage the state of the log
103  * writing process.
104  *
105  * This is an opaque datatype.
106  **/
107 typedef struct journal_s        journal_t;      /* Journal control structure */
108 #endif
109 
110 /*
111  * Internal structures used by the logging mechanism:
112  */
113 
114 #define JBD2_MAGIC_NUMBER 0xc03b3998U /* The first 4 bytes of /dev/random! */
115 
116 /*
117  * On-disk structures
118  */
119 
120 /*
121  * Descriptor block types:
122  */
123 
124 #define JBD2_DESCRIPTOR_BLOCK   1
125 #define JBD2_COMMIT_BLOCK       2
126 #define JBD2_SUPERBLOCK_V1      3
127 #define JBD2_SUPERBLOCK_V2      4
128 #define JBD2_REVOKE_BLOCK       5
129 
130 /*
131  * Standard header for all descriptor blocks:
132  */
133 typedef struct journal_header_s
134 {
135         __be32          h_magic;
136         __be32          h_blocktype;
137         __be32          h_sequence;
138 } journal_header_t;
139 
140 /*
141  * Checksum types.
142  */
143 #define JBD2_CRC32_CHKSUM   1
144 #define JBD2_MD5_CHKSUM     2
145 #define JBD2_SHA1_CHKSUM    3
146 #define JBD2_CRC32C_CHKSUM  4
147 
148 #define JBD2_CRC32_CHKSUM_SIZE 4
149 
150 #define JBD2_CHECKSUM_BYTES (32 / sizeof(u32))
151 /*
152  * Commit block header for storing transactional checksums:
153  *
154  * NOTE: If FEATURE_COMPAT_CHECKSUM (checksum v1) is set, the h_chksum*
155  * fields are used to store a checksum of the descriptor and data blocks.
156  *
157  * If FEATURE_INCOMPAT_CSUM_V2 (checksum v2) is set, then the h_chksum
158  * field is used to store crc32c(uuid+commit_block).  Each journal metadata
159  * block gets its own checksum, and data block checksums are stored in
160  * journal_block_tag (in the descriptor).  The other h_chksum* fields are
161  * not used.
162  *
163  * If FEATURE_INCOMPAT_CSUM_V3 is set, the descriptor block uses
164  * journal_block_tag3_t to store a full 32-bit checksum.  Everything else
165  * is the same as v2.
166  *
167  * Checksum v1, v2, and v3 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_tag3_s
188 {
189         __be32          t_blocknr;      /* The on-disk block number */
190         __be32          t_flags;        /* See below */
191         __be32          t_blocknr_high; /* most-significant high 32bits. */
192         __be32          t_checksum;     /* crc32c(uuid+seq+block) */
193 } journal_block_tag3_t;
194 
195 typedef struct journal_block_tag_s
196 {
197         __be32          t_blocknr;      /* The on-disk block number */
198         __be16          t_checksum;     /* truncated crc32c(uuid+seq+block) */
199         __be16          t_flags;        /* See below */
200         __be32          t_blocknr_high; /* most-significant high 32bits. */
201 } journal_block_tag_t;
202 
203 /* Tail of descriptor or revoke block, for checksumming */
204 struct jbd2_journal_block_tail {
205         __be32          t_checksum;     /* crc32c(uuid+descr_block) */
206 };
207 
208 /*
209  * The revoke descriptor: used on disk to describe a series of blocks to
210  * be revoked from the log
211  */
212 typedef struct jbd2_journal_revoke_header_s
213 {
214         journal_header_t r_header;
215         __be32           r_count;       /* Count of bytes used in the block */
216 } jbd2_journal_revoke_header_t;
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 /* Use the jbd2_{has,set,clear}_feature_* helpers; these will be removed */
277 #define JBD2_HAS_COMPAT_FEATURE(j,mask)                                 \
278         ((j)->j_format_version >= 2 &&                                  \
279          ((j)->j_superblock->s_feature_compat & cpu_to_be32((mask))))
280 #define JBD2_HAS_RO_COMPAT_FEATURE(j,mask)                              \
281         ((j)->j_format_version >= 2 &&                                  \
282          ((j)->j_superblock->s_feature_ro_compat & cpu_to_be32((mask))))
283 #define JBD2_HAS_INCOMPAT_FEATURE(j,mask)                               \
284         ((j)->j_format_version >= 2 &&                                  \
285          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
286 
287 #define JBD2_FEATURE_COMPAT_CHECKSUM            0x00000001
288 
289 #define JBD2_FEATURE_INCOMPAT_REVOKE            0x00000001
290 #define JBD2_FEATURE_INCOMPAT_64BIT             0x00000002
291 #define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT      0x00000004
292 #define JBD2_FEATURE_INCOMPAT_CSUM_V2           0x00000008
293 #define JBD2_FEATURE_INCOMPAT_CSUM_V3           0x00000010
294 
295 /* See "journal feature predicate functions" below */
296 
297 /* Features known to this kernel version: */
298 #define JBD2_KNOWN_COMPAT_FEATURES      JBD2_FEATURE_COMPAT_CHECKSUM
299 #define JBD2_KNOWN_ROCOMPAT_FEATURES    0
300 #define JBD2_KNOWN_INCOMPAT_FEATURES    (JBD2_FEATURE_INCOMPAT_REVOKE | \
301                                         JBD2_FEATURE_INCOMPAT_64BIT | \
302                                         JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT | \
303                                         JBD2_FEATURE_INCOMPAT_CSUM_V2 | \
304                                         JBD2_FEATURE_INCOMPAT_CSUM_V3)
305 
306 #ifdef __KERNEL__
307 
308 #include <linux/fs.h>
309 #include <linux/sched.h>
310 
311 enum jbd_state_bits {
312         BH_JBD                  /* Has an attached ext3 journal_head */
313           = BH_PrivateStart,
314         BH_JWrite,              /* Being written to log (@@@ DEBUGGING) */
315         BH_Freed,               /* Has been freed (truncated) */
316         BH_Revoked,             /* Has been revoked from the log */
317         BH_RevokeValid,         /* Revoked flag is valid */
318         BH_JBDDirty,            /* Is dirty but journaled */
319         BH_State,               /* Pins most journal_head state */
320         BH_JournalHead,         /* Pins bh->b_private and jh->b_bh */
321         BH_Shadow,              /* IO on shadow buffer is running */
322         BH_Verified,            /* Metadata block has been verified ok */
323         BH_JBDPrivateStart,     /* First bit available for private use by FS */
324 };
325 
326 BUFFER_FNS(JBD, jbd)
327 BUFFER_FNS(JWrite, jwrite)
328 BUFFER_FNS(JBDDirty, jbddirty)
329 TAS_BUFFER_FNS(JBDDirty, jbddirty)
330 BUFFER_FNS(Revoked, revoked)
331 TAS_BUFFER_FNS(Revoked, revoked)
332 BUFFER_FNS(RevokeValid, revokevalid)
333 TAS_BUFFER_FNS(RevokeValid, revokevalid)
334 BUFFER_FNS(Freed, freed)
335 BUFFER_FNS(Shadow, shadow)
336 BUFFER_FNS(Verified, verified)
337 
338 static inline struct buffer_head *jh2bh(struct journal_head *jh)
339 {
340         return jh->b_bh;
341 }
342 
343 static inline struct journal_head *bh2jh(struct buffer_head *bh)
344 {
345         return bh->b_private;
346 }
347 
348 static inline void jbd_lock_bh_state(struct buffer_head *bh)
349 {
350         bit_spin_lock(BH_State, &bh->b_state);
351 }
352 
353 static inline int jbd_trylock_bh_state(struct buffer_head *bh)
354 {
355         return bit_spin_trylock(BH_State, &bh->b_state);
356 }
357 
358 static inline int jbd_is_locked_bh_state(struct buffer_head *bh)
359 {
360         return bit_spin_is_locked(BH_State, &bh->b_state);
361 }
362 
363 static inline void jbd_unlock_bh_state(struct buffer_head *bh)
364 {
365         bit_spin_unlock(BH_State, &bh->b_state);
366 }
367 
368 static inline void jbd_lock_bh_journal_head(struct buffer_head *bh)
369 {
370         bit_spin_lock(BH_JournalHead, &bh->b_state);
371 }
372 
373 static inline void jbd_unlock_bh_journal_head(struct buffer_head *bh)
374 {
375         bit_spin_unlock(BH_JournalHead, &bh->b_state);
376 }
377 
378 #define J_ASSERT(assert)        BUG_ON(!(assert))
379 
380 #define J_ASSERT_BH(bh, expr)   J_ASSERT(expr)
381 #define J_ASSERT_JH(jh, expr)   J_ASSERT(expr)
382 
383 #if defined(JBD2_PARANOID_IOFAIL)
384 #define J_EXPECT(expr, why...)          J_ASSERT(expr)
385 #define J_EXPECT_BH(bh, expr, why...)   J_ASSERT_BH(bh, expr)
386 #define J_EXPECT_JH(jh, expr, why...)   J_ASSERT_JH(jh, expr)
387 #else
388 #define __journal_expect(expr, why...)                                       \
389         ({                                                                   \
390                 int val = (expr);                                            \
391                 if (!val) {                                                  \
392                         printk(KERN_ERR                                      \
393                                "JBD2 unexpected failure: %s: %s;\n",         \
394                                __func__, #expr);                             \
395                         printk(KERN_ERR why "\n");                           \
396                 }                                                            \
397                 val;                                                         \
398         })
399 #define J_EXPECT(expr, why...)          __journal_expect(expr, ## why)
400 #define J_EXPECT_BH(bh, expr, why...)   __journal_expect(expr, ## why)
401 #define J_EXPECT_JH(jh, expr, why...)   __journal_expect(expr, ## why)
402 #endif
403 
404 /* Flags in jbd_inode->i_flags */
405 #define __JI_COMMIT_RUNNING 0
406 #define __JI_WRITE_DATA 1
407 #define __JI_WAIT_DATA 2
408 
409 /*
410  * Commit of the inode data in progress. We use this flag to protect us from
411  * concurrent deletion of inode. We cannot use reference to inode for this
412  * since we cannot afford doing last iput() on behalf of kjournald
413  */
414 #define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING)
415 /* Write allocated dirty buffers in this inode before commit */
416 #define JI_WRITE_DATA (1 << __JI_WRITE_DATA)
417 /* Wait for outstanding data writes for this inode before commit */
418 #define JI_WAIT_DATA (1 << __JI_WAIT_DATA)
419 
420 /**
421  * struct jbd_inode is the structure linking inodes in ordered mode
422  *   present in a transaction so that we can sync them during commit.
423  */
424 struct jbd2_inode {
425         /* Which transaction does this inode belong to? Either the running
426          * transaction or the committing one. [j_list_lock] */
427         transaction_t *i_transaction;
428 
429         /* Pointer to the running transaction modifying inode's data in case
430          * there is already a committing transaction touching it. [j_list_lock] */
431         transaction_t *i_next_transaction;
432 
433         /* List of inodes in the i_transaction [j_list_lock] */
434         struct list_head i_list;
435 
436         /* VFS inode this inode belongs to [constant during the lifetime
437          * of the structure] */
438         struct inode *i_vfs_inode;
439 
440         /* Flags of inode [j_list_lock] */
441         unsigned long i_flags;
442 };
443 
444 struct jbd2_revoke_table_s;
445 
446 /**
447  * struct handle_s - The handle_s type is the concrete type associated with
448  *     handle_t.
449  * @h_transaction: Which compound transaction is this update a part of?
450  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
451  * @h_ref: Reference count on this handle
452  * @h_err: Field for caller's use to track errors through large fs operations
453  * @h_sync: flag for sync-on-close
454  * @h_jdata: flag to force data journaling
455  * @h_aborted: flag indicating fatal error on handle
456  **/
457 
458 /* Docbook can't yet cope with the bit fields, but will leave the documentation
459  * in so it can be fixed later.
460  */
461 
462 struct jbd2_journal_handle
463 {
464         union {
465                 /* Which compound transaction is this update a part of? */
466                 transaction_t   *h_transaction;
467                 /* Which journal handle belongs to - used iff h_reserved set */
468                 journal_t       *h_journal;
469         };
470 
471         /* Handle reserved for finishing the logical operation */
472         handle_t                *h_rsv_handle;
473 
474         /* Number of remaining buffers we are allowed to dirty: */
475         int                     h_buffer_credits;
476 
477         /* Reference count on this handle */
478         int                     h_ref;
479 
480         /* Field for caller's use to track errors through large fs */
481         /* operations */
482         int                     h_err;
483 
484         /* Flags [no locking] */
485         unsigned int    h_sync:         1;      /* sync-on-close */
486         unsigned int    h_jdata:        1;      /* force data journaling */
487         unsigned int    h_reserved:     1;      /* handle with reserved credits */
488         unsigned int    h_aborted:      1;      /* fatal error on handle */
489         unsigned int    h_type:         8;      /* for handle statistics */
490         unsigned int    h_line_no:      16;     /* for handle statistics */
491 
492         unsigned long           h_start_jiffies;
493         unsigned int            h_requested_credits;
494 
495 #ifdef CONFIG_DEBUG_LOCK_ALLOC
496         struct lockdep_map      h_lockdep_map;
497 #endif
498 };
499 
500 
501 /*
502  * Some stats for checkpoint phase
503  */
504 struct transaction_chp_stats_s {
505         unsigned long           cs_chp_time;
506         __u32                   cs_forced_to_close;
507         __u32                   cs_written;
508         __u32                   cs_dropped;
509 };
510 
511 /* The transaction_t type is the guts of the journaling mechanism.  It
512  * tracks a compound transaction through its various states:
513  *
514  * RUNNING:     accepting new updates
515  * LOCKED:      Updates still running but we don't accept new ones
516  * RUNDOWN:     Updates are tidying up but have finished requesting
517  *              new buffers to modify (state not used for now)
518  * FLUSH:       All updates complete, but we are still writing to disk
519  * COMMIT:      All data on disk, writing commit record
520  * FINISHED:    We still have to keep the transaction for checkpointing.
521  *
522  * The transaction keeps track of all of the buffers modified by a
523  * running transaction, and all of the buffers committed but not yet
524  * flushed to home for finished transactions.
525  */
526 
527 /*
528  * Lock ranking:
529  *
530  *    j_list_lock
531  *      ->jbd_lock_bh_journal_head()    (This is "innermost")
532  *
533  *    j_state_lock
534  *    ->jbd_lock_bh_state()
535  *
536  *    jbd_lock_bh_state()
537  *    ->j_list_lock
538  *
539  *    j_state_lock
540  *    ->t_handle_lock
541  *
542  *    j_state_lock
543  *    ->j_list_lock                     (journal_unmap_buffer)
544  *
545  */
546 
547 struct transaction_s
548 {
549         /* Pointer to the journal for this transaction. [no locking] */
550         journal_t               *t_journal;
551 
552         /* Sequence number for this transaction [no locking] */
553         tid_t                   t_tid;
554 
555         /*
556          * Transaction's current state
557          * [no locking - only kjournald2 alters this]
558          * [j_list_lock] guards transition of a transaction into T_FINISHED
559          * state and subsequent call of __jbd2_journal_drop_transaction()
560          * FIXME: needs barriers
561          * KLUDGE: [use j_state_lock]
562          */
563         enum {
564                 T_RUNNING,
565                 T_LOCKED,
566                 T_FLUSH,
567                 T_COMMIT,
568                 T_COMMIT_DFLUSH,
569                 T_COMMIT_JFLUSH,
570                 T_COMMIT_CALLBACK,
571                 T_FINISHED
572         }                       t_state;
573 
574         /*
575          * Where in the log does this transaction's commit start? [no locking]
576          */
577         unsigned long           t_log_start;
578 
579         /* Number of buffers on the t_buffers list [j_list_lock] */
580         int                     t_nr_buffers;
581 
582         /*
583          * Doubly-linked circular list of all buffers reserved but not yet
584          * modified by this transaction [j_list_lock]
585          */
586         struct journal_head     *t_reserved_list;
587 
588         /*
589          * Doubly-linked circular list of all metadata buffers owned by this
590          * transaction [j_list_lock]
591          */
592         struct journal_head     *t_buffers;
593 
594         /*
595          * Doubly-linked circular list of all forget buffers (superseded
596          * buffers which we can un-checkpoint once this transaction commits)
597          * [j_list_lock]
598          */
599         struct journal_head     *t_forget;
600 
601         /*
602          * Doubly-linked circular list of all buffers still to be flushed before
603          * this transaction can be checkpointed. [j_list_lock]
604          */
605         struct journal_head     *t_checkpoint_list;
606 
607         /*
608          * Doubly-linked circular list of all buffers submitted for IO while
609          * checkpointing. [j_list_lock]
610          */
611         struct journal_head     *t_checkpoint_io_list;
612 
613         /*
614          * Doubly-linked circular list of metadata buffers being shadowed by log
615          * IO.  The IO buffers on the iobuf list and the shadow buffers on this
616          * list match each other one for one at all times. [j_list_lock]
617          */
618         struct journal_head     *t_shadow_list;
619 
620         /*
621          * List of inodes whose data we've modified in data=ordered mode.
622          * [j_list_lock]
623          */
624         struct list_head        t_inode_list;
625 
626         /*
627          * Protects info related to handles
628          */
629         spinlock_t              t_handle_lock;
630 
631         /*
632          * Longest time some handle had to wait for running transaction
633          */
634         unsigned long           t_max_wait;
635 
636         /*
637          * When transaction started
638          */
639         unsigned long           t_start;
640 
641         /*
642          * When commit was requested
643          */
644         unsigned long           t_requested;
645 
646         /*
647          * Checkpointing stats [j_checkpoint_sem]
648          */
649         struct transaction_chp_stats_s t_chp_stats;
650 
651         /*
652          * Number of outstanding updates running on this transaction
653          * [t_handle_lock]
654          */
655         atomic_t                t_updates;
656 
657         /*
658          * Number of buffers reserved for use by all handles in this transaction
659          * handle but not yet modified. [t_handle_lock]
660          */
661         atomic_t                t_outstanding_credits;
662 
663         /*
664          * Forward and backward links for the circular list of all transactions
665          * awaiting checkpoint. [j_list_lock]
666          */
667         transaction_t           *t_cpnext, *t_cpprev;
668 
669         /*
670          * When will the transaction expire (become due for commit), in jiffies?
671          * [no locking]
672          */
673         unsigned long           t_expires;
674 
675         /*
676          * When this transaction started, in nanoseconds [no locking]
677          */
678         ktime_t                 t_start_time;
679 
680         /*
681          * How many handles used this transaction? [t_handle_lock]
682          */
683         atomic_t                t_handle_count;
684 
685         /*
686          * This transaction is being forced and some process is
687          * waiting for it to finish.
688          */
689         unsigned int t_synchronous_commit:1;
690 
691         /* Disk flush needs to be sent to fs partition [no locking] */
692         int                     t_need_data_flush;
693 
694         /*
695          * For use by the filesystem to store fs-specific data
696          * structures associated with the transaction
697          */
698         struct list_head        t_private_list;
699 };
700 
701 struct transaction_run_stats_s {
702         unsigned long           rs_wait;
703         unsigned long           rs_request_delay;
704         unsigned long           rs_running;
705         unsigned long           rs_locked;
706         unsigned long           rs_flushing;
707         unsigned long           rs_logging;
708 
709         __u32                   rs_handle_count;
710         __u32                   rs_blocks;
711         __u32                   rs_blocks_logged;
712 };
713 
714 struct transaction_stats_s {
715         unsigned long           ts_tid;
716         unsigned long           ts_requested;
717         struct transaction_run_stats_s run;
718 };
719 
720 static inline unsigned long
721 jbd2_time_diff(unsigned long start, unsigned long end)
722 {
723         if (end >= start)
724                 return end - start;
725 
726         return end + (MAX_JIFFY_OFFSET - start);
727 }
728 
729 #define JBD2_NR_BATCH   64
730 
731 /**
732  * struct journal_s - The journal_s type is the concrete type associated with
733  *     journal_t.
734  * @j_flags:  General journaling state flags
735  * @j_errno:  Is there an outstanding uncleared error on the journal (from a
736  *     prior abort)?
737  * @j_sb_buffer: First part of superblock buffer
738  * @j_superblock: Second part of superblock buffer
739  * @j_format_version: Version of the superblock format
740  * @j_state_lock: Protect the various scalars in the journal
741  * @j_barrier_count:  Number of processes waiting to create a barrier lock
742  * @j_barrier: The barrier lock itself
743  * @j_running_transaction: The current running transaction..
744  * @j_committing_transaction: the transaction we are pushing to disk
745  * @j_checkpoint_transactions: a linked circular list of all transactions
746  *  waiting for checkpointing
747  * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
748  *  to start committing, or for a barrier lock to be released
749  * @j_wait_done_commit: Wait queue for waiting for commit to complete
750  * @j_wait_commit: Wait queue to trigger commit
751  * @j_wait_updates: Wait queue to wait for updates to complete
752  * @j_wait_reserved: Wait queue to wait for reserved buffer credits to drop
753  * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
754  * @j_head: Journal head - identifies the first unused block in the journal
755  * @j_tail: Journal tail - identifies the oldest still-used block in the
756  *  journal.
757  * @j_free: Journal free - how many free blocks are there in the journal?
758  * @j_first: The block number of the first usable block
759  * @j_last: The block number one beyond the last usable block
760  * @j_dev: Device where we store the journal
761  * @j_blocksize: blocksize for the location where we store the journal.
762  * @j_blk_offset: starting block offset for into the device where we store the
763  *     journal
764  * @j_fs_dev: Device which holds the client fs.  For internal journal this will
765  *     be equal to j_dev
766  * @j_reserved_credits: Number of buffers reserved from the running transaction
767  * @j_maxlen: Total maximum capacity of the journal region on disk.
768  * @j_list_lock: Protects the buffer lists and internal buffer state.
769  * @j_inode: Optional inode where we store the journal.  If present, all journal
770  *     block numbers are mapped into this inode via bmap().
771  * @j_tail_sequence:  Sequence number of the oldest transaction in the log
772  * @j_transaction_sequence: Sequence number of the next transaction to grant
773  * @j_commit_sequence: Sequence number of the most recently committed
774  *  transaction
775  * @j_commit_request: Sequence number of the most recent transaction wanting
776  *     commit
777  * @j_uuid: Uuid of client object.
778  * @j_task: Pointer to the current commit thread for this journal
779  * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
780  *     single compound commit transaction
781  * @j_commit_interval: What is the maximum transaction lifetime before we begin
782  *  a commit?
783  * @j_commit_timer:  The timer used to wakeup the commit thread
784  * @j_revoke_lock: Protect the revoke table
785  * @j_revoke: The revoke table - maintains the list of revoked blocks in the
786  *     current transaction.
787  * @j_revoke_table: alternate revoke tables for j_revoke
788  * @j_wbuf: array of buffer_heads for jbd2_journal_commit_transaction
789  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
790  *      number that will fit in j_blocksize
791  * @j_last_sync_writer: most recent pid which did a synchronous write
792  * @j_history_lock: Protect the transactions statistics history
793  * @j_proc_entry: procfs entry for the jbd statistics directory
794  * @j_stats: Overall statistics
795  * @j_private: An opaque pointer to fs-private information.
796  */
797 
798 struct journal_s
799 {
800         /* General journaling state flags [j_state_lock] */
801         unsigned long           j_flags;
802 
803         /*
804          * Is there an outstanding uncleared error on the journal (from a prior
805          * abort)? [j_state_lock]
806          */
807         int                     j_errno;
808 
809         /* The superblock buffer */
810         struct buffer_head      *j_sb_buffer;
811         journal_superblock_t    *j_superblock;
812 
813         /* Version of the superblock format */
814         int                     j_format_version;
815 
816         /*
817          * Protect the various scalars in the journal
818          */
819         rwlock_t                j_state_lock;
820 
821         /*
822          * Number of processes waiting to create a barrier lock [j_state_lock]
823          */
824         int                     j_barrier_count;
825 
826         /* The barrier lock itself */
827         struct mutex            j_barrier;
828 
829         /*
830          * Transactions: The current running transaction...
831          * [j_state_lock] [caller holding open handle]
832          */
833         transaction_t           *j_running_transaction;
834 
835         /*
836          * the transaction we are pushing to disk
837          * [j_state_lock] [caller holding open handle]
838          */
839         transaction_t           *j_committing_transaction;
840 
841         /*
842          * ... and a linked circular list of all transactions waiting for
843          * checkpointing. [j_list_lock]
844          */
845         transaction_t           *j_checkpoint_transactions;
846 
847         /*
848          * Wait queue for waiting for a locked transaction to start committing,
849          * or for a barrier lock to be released
850          */
851         wait_queue_head_t       j_wait_transaction_locked;
852 
853         /* Wait queue for waiting for commit to complete */
854         wait_queue_head_t       j_wait_done_commit;
855 
856         /* Wait queue to trigger commit */
857         wait_queue_head_t       j_wait_commit;
858 
859         /* Wait queue to wait for updates to complete */
860         wait_queue_head_t       j_wait_updates;
861 
862         /* Wait queue to wait for reserved buffer credits to drop */
863         wait_queue_head_t       j_wait_reserved;
864 
865         /* Semaphore for locking against concurrent checkpoints */
866         struct mutex            j_checkpoint_mutex;
867 
868         /*
869          * List of buffer heads used by the checkpoint routine.  This
870          * was moved from jbd2_log_do_checkpoint() to reduce stack
871          * usage.  Access to this array is controlled by the
872          * j_checkpoint_mutex.  [j_checkpoint_mutex]
873          */
874         struct buffer_head      *j_chkpt_bhs[JBD2_NR_BATCH];
875         
876         /*
877          * Journal head: identifies the first unused block in the journal.
878          * [j_state_lock]
879          */
880         unsigned long           j_head;
881 
882         /*
883          * Journal tail: identifies the oldest still-used block in the journal.
884          * [j_state_lock]
885          */
886         unsigned long           j_tail;
887 
888         /*
889          * Journal free: how many free blocks are there in the journal?
890          * [j_state_lock]
891          */
892         unsigned long           j_free;
893 
894         /*
895          * Journal start and end: the block numbers of the first usable block
896          * and one beyond the last usable block in the journal. [j_state_lock]
897          */
898         unsigned long           j_first;
899         unsigned long           j_last;
900 
901         /*
902          * Device, blocksize and starting block offset for the location where we
903          * store the journal.
904          */
905         struct block_device     *j_dev;
906         int                     j_blocksize;
907         unsigned long long      j_blk_offset;
908         char                    j_devname[BDEVNAME_SIZE+24];
909 
910         /*
911          * Device which holds the client fs.  For internal journal this will be
912          * equal to j_dev.
913          */
914         struct block_device     *j_fs_dev;
915 
916         /* Total maximum capacity of the journal region on disk. */
917         unsigned int            j_maxlen;
918 
919         /* Number of buffers reserved from the running transaction */
920         atomic_t                j_reserved_credits;
921 
922         /*
923          * Protects the buffer lists and internal buffer state.
924          */
925         spinlock_t              j_list_lock;
926 
927         /* Optional inode where we store the journal.  If present, all */
928         /* journal block numbers are mapped into this inode via */
929         /* bmap(). */
930         struct inode            *j_inode;
931 
932         /*
933          * Sequence number of the oldest transaction in the log [j_state_lock]
934          */
935         tid_t                   j_tail_sequence;
936 
937         /*
938          * Sequence number of the next transaction to grant [j_state_lock]
939          */
940         tid_t                   j_transaction_sequence;
941 
942         /*
943          * Sequence number of the most recently committed transaction
944          * [j_state_lock].
945          */
946         tid_t                   j_commit_sequence;
947 
948         /*
949          * Sequence number of the most recent transaction wanting commit
950          * [j_state_lock]
951          */
952         tid_t                   j_commit_request;
953 
954         /*
955          * Journal uuid: identifies the object (filesystem, LVM volume etc)
956          * backed by this journal.  This will eventually be replaced by an array
957          * of uuids, allowing us to index multiple devices within a single
958          * journal and to perform atomic updates across them.
959          */
960         __u8                    j_uuid[16];
961 
962         /* Pointer to the current commit thread for this journal */
963         struct task_struct      *j_task;
964 
965         /*
966          * Maximum number of metadata buffers to allow in a single compound
967          * commit transaction
968          */
969         int                     j_max_transaction_buffers;
970 
971         /*
972          * What is the maximum transaction lifetime before we begin a commit?
973          */
974         unsigned long           j_commit_interval;
975 
976         /* The timer used to wakeup the commit thread: */
977         struct timer_list       j_commit_timer;
978 
979         /*
980          * The revoke table: maintains the list of revoked blocks in the
981          * current transaction.  [j_revoke_lock]
982          */
983         spinlock_t              j_revoke_lock;
984         struct jbd2_revoke_table_s *j_revoke;
985         struct jbd2_revoke_table_s *j_revoke_table[2];
986 
987         /*
988          * array of bhs for jbd2_journal_commit_transaction
989          */
990         struct buffer_head      **j_wbuf;
991         int                     j_wbufsize;
992 
993         /*
994          * this is the pid of hte last person to run a synchronous operation
995          * through the journal
996          */
997         pid_t                   j_last_sync_writer;
998 
999         /*
1000          * the average amount of time in nanoseconds it takes to commit a
1001          * transaction to disk. [j_state_lock]
1002          */
1003         u64                     j_average_commit_time;
1004 
1005         /*
1006          * minimum and maximum times that we should wait for
1007          * additional filesystem operations to get batched into a
1008          * synchronous handle in microseconds
1009          */
1010         u32                     j_min_batch_time;
1011         u32                     j_max_batch_time;
1012 
1013         /* This function is called when a transaction is closed */
1014         void                    (*j_commit_callback)(journal_t *,
1015                                                      transaction_t *);
1016 
1017         /*
1018          * Journal statistics
1019          */
1020         spinlock_t              j_history_lock;
1021         struct proc_dir_entry   *j_proc_entry;
1022         struct transaction_stats_s j_stats;
1023 
1024         /* Failed journal commit ID */
1025         unsigned int            j_failed_commit;
1026 
1027         /*
1028          * An opaque pointer to fs-private information.  ext3 puts its
1029          * superblock pointer here
1030          */
1031         void *j_private;
1032 
1033         /* Reference to checksum algorithm driver via cryptoapi */
1034         struct crypto_shash *j_chksum_driver;
1035 
1036         /* Precomputed journal UUID checksum for seeding other checksums */
1037         __u32 j_csum_seed;
1038 };
1039 
1040 /* journal feature predicate functions */
1041 #define JBD2_FEATURE_COMPAT_FUNCS(name, flagname) \
1042 static inline bool jbd2_has_feature_##name(journal_t *j) \
1043 { \
1044         return ((j)->j_format_version >= 2 && \
1045                 ((j)->j_superblock->s_feature_compat & \
1046                  cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname)) != 0); \
1047 } \
1048 static inline void jbd2_set_feature_##name(journal_t *j) \
1049 { \
1050         (j)->j_superblock->s_feature_compat |= \
1051                 cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname); \
1052 } \
1053 static inline void jbd2_clear_feature_##name(journal_t *j) \
1054 { \
1055         (j)->j_superblock->s_feature_compat &= \
1056                 ~cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname); \
1057 }
1058 
1059 #define JBD2_FEATURE_RO_COMPAT_FUNCS(name, flagname) \
1060 static inline bool jbd2_has_feature_##name(journal_t *j) \
1061 { \
1062         return ((j)->j_format_version >= 2 && \
1063                 ((j)->j_superblock->s_feature_ro_compat & \
1064                  cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname)) != 0); \
1065 } \
1066 static inline void jbd2_set_feature_##name(journal_t *j) \
1067 { \
1068         (j)->j_superblock->s_feature_ro_compat |= \
1069                 cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname); \
1070 } \
1071 static inline void jbd2_clear_feature_##name(journal_t *j) \
1072 { \
1073         (j)->j_superblock->s_feature_ro_compat &= \
1074                 ~cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname); \
1075 }
1076 
1077 #define JBD2_FEATURE_INCOMPAT_FUNCS(name, flagname) \
1078 static inline bool jbd2_has_feature_##name(journal_t *j) \
1079 { \
1080         return ((j)->j_format_version >= 2 && \
1081                 ((j)->j_superblock->s_feature_incompat & \
1082                  cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname)) != 0); \
1083 } \
1084 static inline void jbd2_set_feature_##name(journal_t *j) \
1085 { \
1086         (j)->j_superblock->s_feature_incompat |= \
1087                 cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname); \
1088 } \
1089 static inline void jbd2_clear_feature_##name(journal_t *j) \
1090 { \
1091         (j)->j_superblock->s_feature_incompat &= \
1092                 ~cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname); \
1093 }
1094 
1095 JBD2_FEATURE_COMPAT_FUNCS(checksum,             CHECKSUM)
1096 
1097 JBD2_FEATURE_INCOMPAT_FUNCS(revoke,             REVOKE)
1098 JBD2_FEATURE_INCOMPAT_FUNCS(64bit,              64BIT)
1099 JBD2_FEATURE_INCOMPAT_FUNCS(async_commit,       ASYNC_COMMIT)
1100 JBD2_FEATURE_INCOMPAT_FUNCS(csum2,              CSUM_V2)
1101 JBD2_FEATURE_INCOMPAT_FUNCS(csum3,              CSUM_V3)
1102 
1103 /*
1104  * Journal flag definitions
1105  */
1106 #define JBD2_UNMOUNT    0x001   /* Journal thread is being destroyed */
1107 #define JBD2_ABORT      0x002   /* Journaling has been aborted for errors. */
1108 #define JBD2_ACK_ERR    0x004   /* The errno in the sb has been acked */
1109 #define JBD2_FLUSHED    0x008   /* The journal superblock has been flushed */
1110 #define JBD2_LOADED     0x010   /* The journal superblock has been loaded */
1111 #define JBD2_BARRIER    0x020   /* Use IDE barriers */
1112 #define JBD2_ABORT_ON_SYNCDATA_ERR      0x040   /* Abort the journal on file
1113                                                  * data write error in ordered
1114                                                  * mode */
1115 #define JBD2_REC_ERR    0x080   /* The errno in the sb has been recorded */
1116 
1117 /*
1118  * Function declarations for the journaling transaction and buffer
1119  * management
1120  */
1121 
1122 /* Filing buffers */
1123 extern void jbd2_journal_unfile_buffer(journal_t *, struct journal_head *);
1124 extern void __jbd2_journal_refile_buffer(struct journal_head *);
1125 extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *);
1126 extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
1127 extern void __journal_free_buffer(struct journal_head *bh);
1128 extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
1129 extern void __journal_clean_data_list(transaction_t *transaction);
1130 static inline void jbd2_file_log_bh(struct list_head *head, struct buffer_head *bh)
1131 {
1132         list_add_tail(&bh->b_assoc_buffers, head);
1133 }
1134 static inline void jbd2_unfile_log_bh(struct buffer_head *bh)
1135 {
1136         list_del_init(&bh->b_assoc_buffers);
1137 }
1138 
1139 /* Log buffer allocation */
1140 struct buffer_head *jbd2_journal_get_descriptor_buffer(transaction_t *, int);
1141 void jbd2_descriptor_block_csum_set(journal_t *, struct buffer_head *);
1142 int jbd2_journal_next_log_block(journal_t *, unsigned long long *);
1143 int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
1144                               unsigned long *block);
1145 int __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1146 void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1147 
1148 /* Commit management */
1149 extern void jbd2_journal_commit_transaction(journal_t *);
1150 
1151 /* Checkpoint list management */
1152 void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy);
1153 int __jbd2_journal_remove_checkpoint(struct journal_head *);
1154 void jbd2_journal_destroy_checkpoint(journal_t *journal);
1155 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
1156 
1157 
1158 /*
1159  * Triggers
1160  */
1161 
1162 struct jbd2_buffer_trigger_type {
1163         /*
1164          * Fired a the moment data to write to the journal are known to be
1165          * stable - so either at the moment b_frozen_data is created or just
1166          * before a buffer is written to the journal.  mapped_data is a mapped
1167          * buffer that is the frozen data for commit.
1168          */
1169         void (*t_frozen)(struct jbd2_buffer_trigger_type *type,
1170                          struct buffer_head *bh, void *mapped_data,
1171                          size_t size);
1172 
1173         /*
1174          * Fired during journal abort for dirty buffers that will not be
1175          * committed.
1176          */
1177         void (*t_abort)(struct jbd2_buffer_trigger_type *type,
1178                         struct buffer_head *bh);
1179 };
1180 
1181 extern void jbd2_buffer_frozen_trigger(struct journal_head *jh,
1182                                        void *mapped_data,
1183                                        struct jbd2_buffer_trigger_type *triggers);
1184 extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
1185                                       struct jbd2_buffer_trigger_type *triggers);
1186 
1187 /* Buffer IO */
1188 extern int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
1189                                               struct journal_head *jh_in,
1190                                               struct buffer_head **bh_out,
1191                                               sector_t blocknr);
1192 
1193 /* Transaction locking */
1194 extern void             __wait_on_journal (journal_t *);
1195 
1196 /* Transaction cache support */
1197 extern void jbd2_journal_destroy_transaction_cache(void);
1198 extern int  jbd2_journal_init_transaction_cache(void);
1199 extern void jbd2_journal_free_transaction(transaction_t *);
1200 
1201 /*
1202  * Journal locking.
1203  *
1204  * We need to lock the journal during transaction state changes so that nobody
1205  * ever tries to take a handle on the running transaction while we are in the
1206  * middle of moving it to the commit phase.  j_state_lock does this.
1207  *
1208  * Note that the locking is completely interrupt unsafe.  We never touch
1209  * journal structures from interrupts.
1210  */
1211 
1212 static inline handle_t *journal_current_handle(void)
1213 {
1214         return current->journal_info;
1215 }
1216 
1217 /* The journaling code user interface:
1218  *
1219  * Create and destroy handles
1220  * Register buffer modifications against the current transaction.
1221  */
1222 
1223 extern handle_t *jbd2_journal_start(journal_t *, int nblocks);
1224 extern handle_t *jbd2__journal_start(journal_t *, int blocks, int rsv_blocks,
1225                                      gfp_t gfp_mask, unsigned int type,
1226                                      unsigned int line_no);
1227 extern int       jbd2_journal_restart(handle_t *, int nblocks);
1228 extern int       jbd2__journal_restart(handle_t *, int nblocks, gfp_t gfp_mask);
1229 extern int       jbd2_journal_start_reserved(handle_t *handle,
1230                                 unsigned int type, unsigned int line_no);
1231 extern void      jbd2_journal_free_reserved(handle_t *handle);
1232 extern int       jbd2_journal_extend (handle_t *, int nblocks);
1233 extern int       jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
1234 extern int       jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
1235 extern int       jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
1236 void             jbd2_journal_set_triggers(struct buffer_head *,
1237                                            struct jbd2_buffer_trigger_type *type);
1238 extern int       jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
1239 extern int       jbd2_journal_forget (handle_t *, struct buffer_head *);
1240 extern void      journal_sync_buffer (struct buffer_head *);
1241 extern int       jbd2_journal_invalidatepage(journal_t *,
1242                                 struct page *, unsigned int, unsigned int);
1243 extern int       jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
1244 extern int       jbd2_journal_stop(handle_t *);
1245 extern int       jbd2_journal_flush (journal_t *);
1246 extern void      jbd2_journal_lock_updates (journal_t *);
1247 extern void      jbd2_journal_unlock_updates (journal_t *);
1248 
1249 extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1250                                 struct block_device *fs_dev,
1251                                 unsigned long long start, int len, int bsize);
1252 extern journal_t * jbd2_journal_init_inode (struct inode *);
1253 extern int         jbd2_journal_update_format (journal_t *);
1254 extern int         jbd2_journal_check_used_features
1255                    (journal_t *, unsigned long, unsigned long, unsigned long);
1256 extern int         jbd2_journal_check_available_features
1257                    (journal_t *, unsigned long, unsigned long, unsigned long);
1258 extern int         jbd2_journal_set_features
1259                    (journal_t *, unsigned long, unsigned long, unsigned long);
1260 extern void        jbd2_journal_clear_features
1261                    (journal_t *, unsigned long, unsigned long, unsigned long);
1262 extern int         jbd2_journal_load       (journal_t *journal);
1263 extern int         jbd2_journal_destroy    (journal_t *);
1264 extern int         jbd2_journal_recover    (journal_t *journal);
1265 extern int         jbd2_journal_wipe       (journal_t *, int);
1266 extern int         jbd2_journal_skip_recovery   (journal_t *);
1267 extern void        jbd2_journal_update_sb_errno(journal_t *);
1268 extern int         jbd2_journal_update_sb_log_tail      (journal_t *, tid_t,
1269                                 unsigned long, int);
1270 extern void        __jbd2_journal_abort_hard    (journal_t *);
1271 extern void        jbd2_journal_abort      (journal_t *, int);
1272 extern int         jbd2_journal_errno      (journal_t *);
1273 extern void        jbd2_journal_ack_err    (journal_t *);
1274 extern int         jbd2_journal_clear_err  (journal_t *);
1275 extern int         jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
1276 extern int         jbd2_journal_force_commit(journal_t *);
1277 extern int         jbd2_journal_force_commit_nested(journal_t *);
1278 extern int         jbd2_journal_inode_add_write(handle_t *handle, struct jbd2_inode *inode);
1279 extern int         jbd2_journal_inode_add_wait(handle_t *handle, struct jbd2_inode *inode);
1280 extern int         jbd2_journal_begin_ordered_truncate(journal_t *journal,
1281                                 struct jbd2_inode *inode, loff_t new_size);
1282 extern void        jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);
1283 extern void        jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode);
1284 
1285 /*
1286  * journal_head management
1287  */
1288 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh);
1289 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh);
1290 void jbd2_journal_put_journal_head(struct journal_head *jh);
1291 
1292 /*
1293  * handle management
1294  */
1295 extern struct kmem_cache *jbd2_handle_cache;
1296 
1297 static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags)
1298 {
1299         return kmem_cache_zalloc(jbd2_handle_cache, gfp_flags);
1300 }
1301 
1302 static inline void jbd2_free_handle(handle_t *handle)
1303 {
1304         kmem_cache_free(jbd2_handle_cache, handle);
1305 }
1306 
1307 /*
1308  * jbd2_inode management (optional, for those file systems that want to use
1309  * dynamically allocated jbd2_inode structures)
1310  */
1311 extern struct kmem_cache *jbd2_inode_cache;
1312 
1313 static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags)
1314 {
1315         return kmem_cache_alloc(jbd2_inode_cache, gfp_flags);
1316 }
1317 
1318 static inline void jbd2_free_inode(struct jbd2_inode *jinode)
1319 {
1320         kmem_cache_free(jbd2_inode_cache, jinode);
1321 }
1322 
1323 /* Primary revoke support */
1324 #define JOURNAL_REVOKE_DEFAULT_HASH 256
1325 extern int         jbd2_journal_init_revoke(journal_t *, int);
1326 extern void        jbd2_journal_destroy_revoke_caches(void);
1327 extern int         jbd2_journal_init_revoke_caches(void);
1328 
1329 extern void        jbd2_journal_destroy_revoke(journal_t *);
1330 extern int         jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *);
1331 extern int         jbd2_journal_cancel_revoke(handle_t *, struct journal_head *);
1332 extern void        jbd2_journal_write_revoke_records(transaction_t *transaction,
1333                                                      struct list_head *log_bufs);
1334 
1335 /* Recovery revoke support */
1336 extern int      jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t);
1337 extern int      jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t);
1338 extern void     jbd2_journal_clear_revoke(journal_t *);
1339 extern void     jbd2_journal_switch_revoke_table(journal_t *journal);
1340 extern void     jbd2_clear_buffer_revoked_flags(journal_t *journal);
1341 
1342 /*
1343  * The log thread user interface:
1344  *
1345  * Request space in the current transaction, and force transaction commit
1346  * transitions on demand.
1347  */
1348 
1349 int jbd2_log_start_commit(journal_t *journal, tid_t tid);
1350 int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
1351 int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
1352 int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
1353 int jbd2_complete_transaction(journal_t *journal, tid_t tid);
1354 int jbd2_log_do_checkpoint(journal_t *journal);
1355 int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
1356 
1357 void __jbd2_log_wait_for_space(journal_t *journal);
1358 extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
1359 extern int jbd2_cleanup_journal_tail(journal_t *);
1360 
1361 /*
1362  * is_journal_abort
1363  *
1364  * Simple test wrapper function to test the JBD2_ABORT state flag.  This
1365  * bit, when set, indicates that we have had a fatal error somewhere,
1366  * either inside the journaling layer or indicated to us by the client
1367  * (eg. ext3), and that we and should not commit any further
1368  * transactions.
1369  */
1370 
1371 static inline int is_journal_aborted(journal_t *journal)
1372 {
1373         return journal->j_flags & JBD2_ABORT;
1374 }
1375 
1376 static inline int is_handle_aborted(handle_t *handle)
1377 {
1378         if (handle->h_aborted || !handle->h_transaction)
1379                 return 1;
1380         return is_journal_aborted(handle->h_transaction->t_journal);
1381 }
1382 
1383 static inline void jbd2_journal_abort_handle(handle_t *handle)
1384 {
1385         handle->h_aborted = 1;
1386 }
1387 
1388 #endif /* __KERNEL__   */
1389 
1390 /* Comparison functions for transaction IDs: perform comparisons using
1391  * modulo arithmetic so that they work over sequence number wraps. */
1392 
1393 static inline int tid_gt(tid_t x, tid_t y)
1394 {
1395         int difference = (x - y);
1396         return (difference > 0);
1397 }
1398 
1399 static inline int tid_geq(tid_t x, tid_t y)
1400 {
1401         int difference = (x - y);
1402         return (difference >= 0);
1403 }
1404 
1405 extern int jbd2_journal_blocks_per_page(struct inode *inode);
1406 extern size_t journal_tag_bytes(journal_t *journal);
1407 
1408 static inline bool jbd2_journal_has_csum_v2or3_feature(journal_t *j)
1409 {
1410         return jbd2_has_feature_csum2(j) || jbd2_has_feature_csum3(j);
1411 }
1412 
1413 static inline int jbd2_journal_has_csum_v2or3(journal_t *journal)
1414 {
1415         WARN_ON_ONCE(jbd2_journal_has_csum_v2or3_feature(journal) &&
1416                      journal->j_chksum_driver == NULL);
1417 
1418         return journal->j_chksum_driver != NULL;
1419 }
1420 
1421 /*
1422  * We reserve t_outstanding_credits >> JBD2_CONTROL_BLOCKS_SHIFT for
1423  * transaction control blocks.
1424  */
1425 #define JBD2_CONTROL_BLOCKS_SHIFT 5
1426 
1427 /*
1428  * Return the minimum number of blocks which must be free in the journal
1429  * before a new transaction may be started.  Must be called under j_state_lock.
1430  */
1431 static inline int jbd2_space_needed(journal_t *journal)
1432 {
1433         int nblocks = journal->j_max_transaction_buffers;
1434         return nblocks + (nblocks >> JBD2_CONTROL_BLOCKS_SHIFT);
1435 }
1436 
1437 /*
1438  * Return number of free blocks in the log. Must be called under j_state_lock.
1439  */
1440 static inline unsigned long jbd2_log_space_left(journal_t *journal)
1441 {
1442         /* Allow for rounding errors */
1443         unsigned long free = journal->j_free - 32;
1444 
1445         if (journal->j_committing_transaction) {
1446                 unsigned long committing = atomic_read(&journal->
1447                         j_committing_transaction->t_outstanding_credits);
1448 
1449                 /* Transaction + control blocks */
1450                 free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT);
1451         }
1452         return free;
1453 }
1454 
1455 /*
1456  * Definitions which augment the buffer_head layer
1457  */
1458 
1459 /* journaling buffer types */
1460 #define BJ_None         0       /* Not journaled */
1461 #define BJ_Metadata     1       /* Normal journaled metadata */
1462 #define BJ_Forget       2       /* Buffer superseded by this transaction */
1463 #define BJ_Shadow       3       /* Buffer contents being shadowed to the log */
1464 #define BJ_Reserved     4       /* Buffer is reserved for access by journal */
1465 #define BJ_Types        5
1466 
1467 extern int jbd_blocks_per_page(struct inode *inode);
1468 
1469 /* JBD uses a CRC32 checksum */
1470 #define JBD_MAX_CHECKSUM_SIZE 4
1471 
1472 static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
1473                               const void *address, unsigned int length)
1474 {
1475         struct {
1476                 struct shash_desc shash;
1477                 char ctx[JBD_MAX_CHECKSUM_SIZE];
1478         } desc;
1479         int err;
1480 
1481         BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >
1482                 JBD_MAX_CHECKSUM_SIZE);
1483 
1484         desc.shash.tfm = journal->j_chksum_driver;
1485         desc.shash.flags = 0;
1486         *(u32 *)desc.ctx = crc;
1487 
1488         err = crypto_shash_update(&desc.shash, address, length);
1489         BUG_ON(err);
1490 
1491         return *(u32 *)desc.ctx;
1492 }
1493 
1494 /* Return most recent uncommitted transaction */
1495 static inline tid_t  jbd2_get_latest_transaction(journal_t *journal)
1496 {
1497         tid_t tid;
1498 
1499         read_lock(&journal->j_state_lock);
1500         tid = journal->j_commit_request;
1501         if (journal->j_running_transaction)
1502                 tid = journal->j_running_transaction->t_tid;
1503         read_unlock(&journal->j_state_lock);
1504         return tid;
1505 }
1506 
1507 #ifdef __KERNEL__
1508 
1509 #define buffer_trace_init(bh)   do {} while (0)
1510 #define print_buffer_fields(bh) do {} while (0)
1511 #define print_buffer_trace(bh)  do {} while (0)
1512 #define BUFFER_TRACE(bh, info)  do {} while (0)
1513 #define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1514 #define JBUFFER_TRACE(jh, info) do {} while (0)
1515 
1516 #endif  /* __KERNEL__ */
1517 
1518 #define EFSBADCRC       EBADMSG         /* Bad CRC detected */
1519 #define EFSCORRUPTED    EUCLEAN         /* Filesystem is corrupted */
1520 
1521 #endif  /* _LINUX_JBD2_H */
1522 

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