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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 /* Commit of the inode data in progress. We use this flag to protect us from
407  * concurrent deletion of inode. We cannot use reference to inode for this
408  * since we cannot afford doing last iput() on behalf of kjournald
409  */
410 #define JI_COMMIT_RUNNING (1 << __JI_COMMIT_RUNNING)
411 
412 /**
413  * struct jbd_inode is the structure linking inodes in ordered mode
414  *   present in a transaction so that we can sync them during commit.
415  */
416 struct jbd2_inode {
417         /* Which transaction does this inode belong to? Either the running
418          * transaction or the committing one. [j_list_lock] */
419         transaction_t *i_transaction;
420 
421         /* Pointer to the running transaction modifying inode's data in case
422          * there is already a committing transaction touching it. [j_list_lock] */
423         transaction_t *i_next_transaction;
424 
425         /* List of inodes in the i_transaction [j_list_lock] */
426         struct list_head i_list;
427 
428         /* VFS inode this inode belongs to [constant during the lifetime
429          * of the structure] */
430         struct inode *i_vfs_inode;
431 
432         /* Flags of inode [j_list_lock] */
433         unsigned long i_flags;
434 };
435 
436 struct jbd2_revoke_table_s;
437 
438 /**
439  * struct handle_s - The handle_s type is the concrete type associated with
440  *     handle_t.
441  * @h_transaction: Which compound transaction is this update a part of?
442  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
443  * @h_ref: Reference count on this handle
444  * @h_err: Field for caller's use to track errors through large fs operations
445  * @h_sync: flag for sync-on-close
446  * @h_jdata: flag to force data journaling
447  * @h_aborted: flag indicating fatal error on handle
448  **/
449 
450 /* Docbook can't yet cope with the bit fields, but will leave the documentation
451  * in so it can be fixed later.
452  */
453 
454 struct jbd2_journal_handle
455 {
456         union {
457                 /* Which compound transaction is this update a part of? */
458                 transaction_t   *h_transaction;
459                 /* Which journal handle belongs to - used iff h_reserved set */
460                 journal_t       *h_journal;
461         };
462 
463         /* Handle reserved for finishing the logical operation */
464         handle_t                *h_rsv_handle;
465 
466         /* Number of remaining buffers we are allowed to dirty: */
467         int                     h_buffer_credits;
468 
469         /* Reference count on this handle */
470         int                     h_ref;
471 
472         /* Field for caller's use to track errors through large fs */
473         /* operations */
474         int                     h_err;
475 
476         /* Flags [no locking] */
477         unsigned int    h_sync:         1;      /* sync-on-close */
478         unsigned int    h_jdata:        1;      /* force data journaling */
479         unsigned int    h_reserved:     1;      /* handle with reserved credits */
480         unsigned int    h_aborted:      1;      /* fatal error on handle */
481         unsigned int    h_type:         8;      /* for handle statistics */
482         unsigned int    h_line_no:      16;     /* for handle statistics */
483 
484         unsigned long           h_start_jiffies;
485         unsigned int            h_requested_credits;
486 
487 #ifdef CONFIG_DEBUG_LOCK_ALLOC
488         struct lockdep_map      h_lockdep_map;
489 #endif
490 };
491 
492 
493 /*
494  * Some stats for checkpoint phase
495  */
496 struct transaction_chp_stats_s {
497         unsigned long           cs_chp_time;
498         __u32                   cs_forced_to_close;
499         __u32                   cs_written;
500         __u32                   cs_dropped;
501 };
502 
503 /* The transaction_t type is the guts of the journaling mechanism.  It
504  * tracks a compound transaction through its various states:
505  *
506  * RUNNING:     accepting new updates
507  * LOCKED:      Updates still running but we don't accept new ones
508  * RUNDOWN:     Updates are tidying up but have finished requesting
509  *              new buffers to modify (state not used for now)
510  * FLUSH:       All updates complete, but we are still writing to disk
511  * COMMIT:      All data on disk, writing commit record
512  * FINISHED:    We still have to keep the transaction for checkpointing.
513  *
514  * The transaction keeps track of all of the buffers modified by a
515  * running transaction, and all of the buffers committed but not yet
516  * flushed to home for finished transactions.
517  */
518 
519 /*
520  * Lock ranking:
521  *
522  *    j_list_lock
523  *      ->jbd_lock_bh_journal_head()    (This is "innermost")
524  *
525  *    j_state_lock
526  *    ->jbd_lock_bh_state()
527  *
528  *    jbd_lock_bh_state()
529  *    ->j_list_lock
530  *
531  *    j_state_lock
532  *    ->t_handle_lock
533  *
534  *    j_state_lock
535  *    ->j_list_lock                     (journal_unmap_buffer)
536  *
537  */
538 
539 struct transaction_s
540 {
541         /* Pointer to the journal for this transaction. [no locking] */
542         journal_t               *t_journal;
543 
544         /* Sequence number for this transaction [no locking] */
545         tid_t                   t_tid;
546 
547         /*
548          * Transaction's current state
549          * [no locking - only kjournald2 alters this]
550          * [j_list_lock] guards transition of a transaction into T_FINISHED
551          * state and subsequent call of __jbd2_journal_drop_transaction()
552          * FIXME: needs barriers
553          * KLUDGE: [use j_state_lock]
554          */
555         enum {
556                 T_RUNNING,
557                 T_LOCKED,
558                 T_FLUSH,
559                 T_COMMIT,
560                 T_COMMIT_DFLUSH,
561                 T_COMMIT_JFLUSH,
562                 T_COMMIT_CALLBACK,
563                 T_FINISHED
564         }                       t_state;
565 
566         /*
567          * Where in the log does this transaction's commit start? [no locking]
568          */
569         unsigned long           t_log_start;
570 
571         /* Number of buffers on the t_buffers list [j_list_lock] */
572         int                     t_nr_buffers;
573 
574         /*
575          * Doubly-linked circular list of all buffers reserved but not yet
576          * modified by this transaction [j_list_lock]
577          */
578         struct journal_head     *t_reserved_list;
579 
580         /*
581          * Doubly-linked circular list of all metadata buffers owned by this
582          * transaction [j_list_lock]
583          */
584         struct journal_head     *t_buffers;
585 
586         /*
587          * Doubly-linked circular list of all forget buffers (superseded
588          * buffers which we can un-checkpoint once this transaction commits)
589          * [j_list_lock]
590          */
591         struct journal_head     *t_forget;
592 
593         /*
594          * Doubly-linked circular list of all buffers still to be flushed before
595          * this transaction can be checkpointed. [j_list_lock]
596          */
597         struct journal_head     *t_checkpoint_list;
598 
599         /*
600          * Doubly-linked circular list of all buffers submitted for IO while
601          * checkpointing. [j_list_lock]
602          */
603         struct journal_head     *t_checkpoint_io_list;
604 
605         /*
606          * Doubly-linked circular list of metadata buffers being shadowed by log
607          * IO.  The IO buffers on the iobuf list and the shadow buffers on this
608          * list match each other one for one at all times. [j_list_lock]
609          */
610         struct journal_head     *t_shadow_list;
611 
612         /*
613          * List of inodes whose data we've modified in data=ordered mode.
614          * [j_list_lock]
615          */
616         struct list_head        t_inode_list;
617 
618         /*
619          * Protects info related to handles
620          */
621         spinlock_t              t_handle_lock;
622 
623         /*
624          * Longest time some handle had to wait for running transaction
625          */
626         unsigned long           t_max_wait;
627 
628         /*
629          * When transaction started
630          */
631         unsigned long           t_start;
632 
633         /*
634          * When commit was requested
635          */
636         unsigned long           t_requested;
637 
638         /*
639          * Checkpointing stats [j_checkpoint_sem]
640          */
641         struct transaction_chp_stats_s t_chp_stats;
642 
643         /*
644          * Number of outstanding updates running on this transaction
645          * [t_handle_lock]
646          */
647         atomic_t                t_updates;
648 
649         /*
650          * Number of buffers reserved for use by all handles in this transaction
651          * handle but not yet modified. [t_handle_lock]
652          */
653         atomic_t                t_outstanding_credits;
654 
655         /*
656          * Forward and backward links for the circular list of all transactions
657          * awaiting checkpoint. [j_list_lock]
658          */
659         transaction_t           *t_cpnext, *t_cpprev;
660 
661         /*
662          * When will the transaction expire (become due for commit), in jiffies?
663          * [no locking]
664          */
665         unsigned long           t_expires;
666 
667         /*
668          * When this transaction started, in nanoseconds [no locking]
669          */
670         ktime_t                 t_start_time;
671 
672         /*
673          * How many handles used this transaction? [t_handle_lock]
674          */
675         atomic_t                t_handle_count;
676 
677         /*
678          * This transaction is being forced and some process is
679          * waiting for it to finish.
680          */
681         unsigned int t_synchronous_commit:1;
682 
683         /* Disk flush needs to be sent to fs partition [no locking] */
684         int                     t_need_data_flush;
685 
686         /*
687          * For use by the filesystem to store fs-specific data
688          * structures associated with the transaction
689          */
690         struct list_head        t_private_list;
691 };
692 
693 struct transaction_run_stats_s {
694         unsigned long           rs_wait;
695         unsigned long           rs_request_delay;
696         unsigned long           rs_running;
697         unsigned long           rs_locked;
698         unsigned long           rs_flushing;
699         unsigned long           rs_logging;
700 
701         __u32                   rs_handle_count;
702         __u32                   rs_blocks;
703         __u32                   rs_blocks_logged;
704 };
705 
706 struct transaction_stats_s {
707         unsigned long           ts_tid;
708         unsigned long           ts_requested;
709         struct transaction_run_stats_s run;
710 };
711 
712 static inline unsigned long
713 jbd2_time_diff(unsigned long start, unsigned long end)
714 {
715         if (end >= start)
716                 return end - start;
717 
718         return end + (MAX_JIFFY_OFFSET - start);
719 }
720 
721 #define JBD2_NR_BATCH   64
722 
723 /**
724  * struct journal_s - The journal_s type is the concrete type associated with
725  *     journal_t.
726  * @j_flags:  General journaling state flags
727  * @j_errno:  Is there an outstanding uncleared error on the journal (from a
728  *     prior abort)?
729  * @j_sb_buffer: First part of superblock buffer
730  * @j_superblock: Second part of superblock buffer
731  * @j_format_version: Version of the superblock format
732  * @j_state_lock: Protect the various scalars in the journal
733  * @j_barrier_count:  Number of processes waiting to create a barrier lock
734  * @j_barrier: The barrier lock itself
735  * @j_running_transaction: The current running transaction..
736  * @j_committing_transaction: the transaction we are pushing to disk
737  * @j_checkpoint_transactions: a linked circular list of all transactions
738  *  waiting for checkpointing
739  * @j_wait_transaction_locked: Wait queue for waiting for a locked transaction
740  *  to start committing, or for a barrier lock to be released
741  * @j_wait_done_commit: Wait queue for waiting for commit to complete
742  * @j_wait_commit: Wait queue to trigger commit
743  * @j_wait_updates: Wait queue to wait for updates to complete
744  * @j_wait_reserved: Wait queue to wait for reserved buffer credits to drop
745  * @j_checkpoint_mutex: Mutex for locking against concurrent checkpoints
746  * @j_head: Journal head - identifies the first unused block in the journal
747  * @j_tail: Journal tail - identifies the oldest still-used block in the
748  *  journal.
749  * @j_free: Journal free - how many free blocks are there in the journal?
750  * @j_first: The block number of the first usable block
751  * @j_last: The block number one beyond the last usable block
752  * @j_dev: Device where we store the journal
753  * @j_blocksize: blocksize for the location where we store the journal.
754  * @j_blk_offset: starting block offset for into the device where we store the
755  *     journal
756  * @j_fs_dev: Device which holds the client fs.  For internal journal this will
757  *     be equal to j_dev
758  * @j_reserved_credits: Number of buffers reserved from the running transaction
759  * @j_maxlen: Total maximum capacity of the journal region on disk.
760  * @j_list_lock: Protects the buffer lists and internal buffer state.
761  * @j_inode: Optional inode where we store the journal.  If present, all journal
762  *     block numbers are mapped into this inode via bmap().
763  * @j_tail_sequence:  Sequence number of the oldest transaction in the log
764  * @j_transaction_sequence: Sequence number of the next transaction to grant
765  * @j_commit_sequence: Sequence number of the most recently committed
766  *  transaction
767  * @j_commit_request: Sequence number of the most recent transaction wanting
768  *     commit
769  * @j_uuid: Uuid of client object.
770  * @j_task: Pointer to the current commit thread for this journal
771  * @j_max_transaction_buffers:  Maximum number of metadata buffers to allow in a
772  *     single compound commit transaction
773  * @j_commit_interval: What is the maximum transaction lifetime before we begin
774  *  a commit?
775  * @j_commit_timer:  The timer used to wakeup the commit thread
776  * @j_revoke_lock: Protect the revoke table
777  * @j_revoke: The revoke table - maintains the list of revoked blocks in the
778  *     current transaction.
779  * @j_revoke_table: alternate revoke tables for j_revoke
780  * @j_wbuf: array of buffer_heads for jbd2_journal_commit_transaction
781  * @j_wbufsize: maximum number of buffer_heads allowed in j_wbuf, the
782  *      number that will fit in j_blocksize
783  * @j_last_sync_writer: most recent pid which did a synchronous write
784  * @j_history: Buffer storing the transactions statistics history
785  * @j_history_max: Maximum number of transactions in the statistics history
786  * @j_history_cur: Current number of transactions in the statistics history
787  * @j_history_lock: Protect the transactions statistics history
788  * @j_proc_entry: procfs entry for the jbd statistics directory
789  * @j_stats: Overall statistics
790  * @j_private: An opaque pointer to fs-private information.
791  */
792 
793 struct journal_s
794 {
795         /* General journaling state flags [j_state_lock] */
796         unsigned long           j_flags;
797 
798         /*
799          * Is there an outstanding uncleared error on the journal (from a prior
800          * abort)? [j_state_lock]
801          */
802         int                     j_errno;
803 
804         /* The superblock buffer */
805         struct buffer_head      *j_sb_buffer;
806         journal_superblock_t    *j_superblock;
807 
808         /* Version of the superblock format */
809         int                     j_format_version;
810 
811         /*
812          * Protect the various scalars in the journal
813          */
814         rwlock_t                j_state_lock;
815 
816         /*
817          * Number of processes waiting to create a barrier lock [j_state_lock]
818          */
819         int                     j_barrier_count;
820 
821         /* The barrier lock itself */
822         struct mutex            j_barrier;
823 
824         /*
825          * Transactions: The current running transaction...
826          * [j_state_lock] [caller holding open handle]
827          */
828         transaction_t           *j_running_transaction;
829 
830         /*
831          * the transaction we are pushing to disk
832          * [j_state_lock] [caller holding open handle]
833          */
834         transaction_t           *j_committing_transaction;
835 
836         /*
837          * ... and a linked circular list of all transactions waiting for
838          * checkpointing. [j_list_lock]
839          */
840         transaction_t           *j_checkpoint_transactions;
841 
842         /*
843          * Wait queue for waiting for a locked transaction to start committing,
844          * or for a barrier lock to be released
845          */
846         wait_queue_head_t       j_wait_transaction_locked;
847 
848         /* Wait queue for waiting for commit to complete */
849         wait_queue_head_t       j_wait_done_commit;
850 
851         /* Wait queue to trigger commit */
852         wait_queue_head_t       j_wait_commit;
853 
854         /* Wait queue to wait for updates to complete */
855         wait_queue_head_t       j_wait_updates;
856 
857         /* Wait queue to wait for reserved buffer credits to drop */
858         wait_queue_head_t       j_wait_reserved;
859 
860         /* Semaphore for locking against concurrent checkpoints */
861         struct mutex            j_checkpoint_mutex;
862 
863         /*
864          * List of buffer heads used by the checkpoint routine.  This
865          * was moved from jbd2_log_do_checkpoint() to reduce stack
866          * usage.  Access to this array is controlled by the
867          * j_checkpoint_mutex.  [j_checkpoint_mutex]
868          */
869         struct buffer_head      *j_chkpt_bhs[JBD2_NR_BATCH];
870         
871         /*
872          * Journal head: identifies the first unused block in the journal.
873          * [j_state_lock]
874          */
875         unsigned long           j_head;
876 
877         /*
878          * Journal tail: identifies the oldest still-used block in the journal.
879          * [j_state_lock]
880          */
881         unsigned long           j_tail;
882 
883         /*
884          * Journal free: how many free blocks are there in the journal?
885          * [j_state_lock]
886          */
887         unsigned long           j_free;
888 
889         /*
890          * Journal start and end: the block numbers of the first usable block
891          * and one beyond the last usable block in the journal. [j_state_lock]
892          */
893         unsigned long           j_first;
894         unsigned long           j_last;
895 
896         /*
897          * Device, blocksize and starting block offset for the location where we
898          * store the journal.
899          */
900         struct block_device     *j_dev;
901         int                     j_blocksize;
902         unsigned long long      j_blk_offset;
903         char                    j_devname[BDEVNAME_SIZE+24];
904 
905         /*
906          * Device which holds the client fs.  For internal journal this will be
907          * equal to j_dev.
908          */
909         struct block_device     *j_fs_dev;
910 
911         /* Total maximum capacity of the journal region on disk. */
912         unsigned int            j_maxlen;
913 
914         /* Number of buffers reserved from the running transaction */
915         atomic_t                j_reserved_credits;
916 
917         /*
918          * Protects the buffer lists and internal buffer state.
919          */
920         spinlock_t              j_list_lock;
921 
922         /* Optional inode where we store the journal.  If present, all */
923         /* journal block numbers are mapped into this inode via */
924         /* bmap(). */
925         struct inode            *j_inode;
926 
927         /*
928          * Sequence number of the oldest transaction in the log [j_state_lock]
929          */
930         tid_t                   j_tail_sequence;
931 
932         /*
933          * Sequence number of the next transaction to grant [j_state_lock]
934          */
935         tid_t                   j_transaction_sequence;
936 
937         /*
938          * Sequence number of the most recently committed transaction
939          * [j_state_lock].
940          */
941         tid_t                   j_commit_sequence;
942 
943         /*
944          * Sequence number of the most recent transaction wanting commit
945          * [j_state_lock]
946          */
947         tid_t                   j_commit_request;
948 
949         /*
950          * Journal uuid: identifies the object (filesystem, LVM volume etc)
951          * backed by this journal.  This will eventually be replaced by an array
952          * of uuids, allowing us to index multiple devices within a single
953          * journal and to perform atomic updates across them.
954          */
955         __u8                    j_uuid[16];
956 
957         /* Pointer to the current commit thread for this journal */
958         struct task_struct      *j_task;
959 
960         /*
961          * Maximum number of metadata buffers to allow in a single compound
962          * commit transaction
963          */
964         int                     j_max_transaction_buffers;
965 
966         /*
967          * What is the maximum transaction lifetime before we begin a commit?
968          */
969         unsigned long           j_commit_interval;
970 
971         /* The timer used to wakeup the commit thread: */
972         struct timer_list       j_commit_timer;
973 
974         /*
975          * The revoke table: maintains the list of revoked blocks in the
976          * current transaction.  [j_revoke_lock]
977          */
978         spinlock_t              j_revoke_lock;
979         struct jbd2_revoke_table_s *j_revoke;
980         struct jbd2_revoke_table_s *j_revoke_table[2];
981 
982         /*
983          * array of bhs for jbd2_journal_commit_transaction
984          */
985         struct buffer_head      **j_wbuf;
986         int                     j_wbufsize;
987 
988         /*
989          * this is the pid of hte last person to run a synchronous operation
990          * through the journal
991          */
992         pid_t                   j_last_sync_writer;
993 
994         /*
995          * the average amount of time in nanoseconds it takes to commit a
996          * transaction to disk. [j_state_lock]
997          */
998         u64                     j_average_commit_time;
999 
1000         /*
1001          * minimum and maximum times that we should wait for
1002          * additional filesystem operations to get batched into a
1003          * synchronous handle in microseconds
1004          */
1005         u32                     j_min_batch_time;
1006         u32                     j_max_batch_time;
1007 
1008         /* This function is called when a transaction is closed */
1009         void                    (*j_commit_callback)(journal_t *,
1010                                                      transaction_t *);
1011 
1012         /*
1013          * Journal statistics
1014          */
1015         spinlock_t              j_history_lock;
1016         struct proc_dir_entry   *j_proc_entry;
1017         struct transaction_stats_s j_stats;
1018 
1019         /* Failed journal commit ID */
1020         unsigned int            j_failed_commit;
1021 
1022         /*
1023          * An opaque pointer to fs-private information.  ext3 puts its
1024          * superblock pointer here
1025          */
1026         void *j_private;
1027 
1028         /* Reference to checksum algorithm driver via cryptoapi */
1029         struct crypto_shash *j_chksum_driver;
1030 
1031         /* Precomputed journal UUID checksum for seeding other checksums */
1032         __u32 j_csum_seed;
1033 };
1034 
1035 /* journal feature predicate functions */
1036 #define JBD2_FEATURE_COMPAT_FUNCS(name, flagname) \
1037 static inline bool jbd2_has_feature_##name(journal_t *j) \
1038 { \
1039         return ((j)->j_format_version >= 2 && \
1040                 ((j)->j_superblock->s_feature_compat & \
1041                  cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname)) != 0); \
1042 } \
1043 static inline void jbd2_set_feature_##name(journal_t *j) \
1044 { \
1045         (j)->j_superblock->s_feature_compat |= \
1046                 cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname); \
1047 } \
1048 static inline void jbd2_clear_feature_##name(journal_t *j) \
1049 { \
1050         (j)->j_superblock->s_feature_compat &= \
1051                 ~cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname); \
1052 }
1053 
1054 #define JBD2_FEATURE_RO_COMPAT_FUNCS(name, flagname) \
1055 static inline bool jbd2_has_feature_##name(journal_t *j) \
1056 { \
1057         return ((j)->j_format_version >= 2 && \
1058                 ((j)->j_superblock->s_feature_ro_compat & \
1059                  cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname)) != 0); \
1060 } \
1061 static inline void jbd2_set_feature_##name(journal_t *j) \
1062 { \
1063         (j)->j_superblock->s_feature_ro_compat |= \
1064                 cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname); \
1065 } \
1066 static inline void jbd2_clear_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 
1072 #define JBD2_FEATURE_INCOMPAT_FUNCS(name, flagname) \
1073 static inline bool jbd2_has_feature_##name(journal_t *j) \
1074 { \
1075         return ((j)->j_format_version >= 2 && \
1076                 ((j)->j_superblock->s_feature_incompat & \
1077                  cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname)) != 0); \
1078 } \
1079 static inline void jbd2_set_feature_##name(journal_t *j) \
1080 { \
1081         (j)->j_superblock->s_feature_incompat |= \
1082                 cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname); \
1083 } \
1084 static inline void jbd2_clear_feature_##name(journal_t *j) \
1085 { \
1086         (j)->j_superblock->s_feature_incompat &= \
1087                 ~cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname); \
1088 }
1089 
1090 JBD2_FEATURE_COMPAT_FUNCS(checksum,             CHECKSUM)
1091 
1092 JBD2_FEATURE_INCOMPAT_FUNCS(revoke,             REVOKE)
1093 JBD2_FEATURE_INCOMPAT_FUNCS(64bit,              64BIT)
1094 JBD2_FEATURE_INCOMPAT_FUNCS(async_commit,       ASYNC_COMMIT)
1095 JBD2_FEATURE_INCOMPAT_FUNCS(csum2,              CSUM_V2)
1096 JBD2_FEATURE_INCOMPAT_FUNCS(csum3,              CSUM_V3)
1097 
1098 /*
1099  * Journal flag definitions
1100  */
1101 #define JBD2_UNMOUNT    0x001   /* Journal thread is being destroyed */
1102 #define JBD2_ABORT      0x002   /* Journaling has been aborted for errors. */
1103 #define JBD2_ACK_ERR    0x004   /* The errno in the sb has been acked */
1104 #define JBD2_FLUSHED    0x008   /* The journal superblock has been flushed */
1105 #define JBD2_LOADED     0x010   /* The journal superblock has been loaded */
1106 #define JBD2_BARRIER    0x020   /* Use IDE barriers */
1107 #define JBD2_ABORT_ON_SYNCDATA_ERR      0x040   /* Abort the journal on file
1108                                                  * data write error in ordered
1109                                                  * mode */
1110 #define JBD2_REC_ERR    0x080   /* The errno in the sb has been recorded */
1111 
1112 /*
1113  * Function declarations for the journaling transaction and buffer
1114  * management
1115  */
1116 
1117 /* Filing buffers */
1118 extern void jbd2_journal_unfile_buffer(journal_t *, struct journal_head *);
1119 extern void __jbd2_journal_refile_buffer(struct journal_head *);
1120 extern void jbd2_journal_refile_buffer(journal_t *, struct journal_head *);
1121 extern void __jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
1122 extern void __journal_free_buffer(struct journal_head *bh);
1123 extern void jbd2_journal_file_buffer(struct journal_head *, transaction_t *, int);
1124 extern void __journal_clean_data_list(transaction_t *transaction);
1125 static inline void jbd2_file_log_bh(struct list_head *head, struct buffer_head *bh)
1126 {
1127         list_add_tail(&bh->b_assoc_buffers, head);
1128 }
1129 static inline void jbd2_unfile_log_bh(struct buffer_head *bh)
1130 {
1131         list_del_init(&bh->b_assoc_buffers);
1132 }
1133 
1134 /* Log buffer allocation */
1135 struct buffer_head *jbd2_journal_get_descriptor_buffer(transaction_t *, int);
1136 void jbd2_descriptor_block_csum_set(journal_t *, struct buffer_head *);
1137 int jbd2_journal_next_log_block(journal_t *, unsigned long long *);
1138 int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
1139                               unsigned long *block);
1140 int __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1141 void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block);
1142 
1143 /* Commit management */
1144 extern void jbd2_journal_commit_transaction(journal_t *);
1145 
1146 /* Checkpoint list management */
1147 void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy);
1148 int __jbd2_journal_remove_checkpoint(struct journal_head *);
1149 void jbd2_journal_destroy_checkpoint(journal_t *journal);
1150 void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
1151 
1152 
1153 /*
1154  * Triggers
1155  */
1156 
1157 struct jbd2_buffer_trigger_type {
1158         /*
1159          * Fired a the moment data to write to the journal are known to be
1160          * stable - so either at the moment b_frozen_data is created or just
1161          * before a buffer is written to the journal.  mapped_data is a mapped
1162          * buffer that is the frozen data for commit.
1163          */
1164         void (*t_frozen)(struct jbd2_buffer_trigger_type *type,
1165                          struct buffer_head *bh, void *mapped_data,
1166                          size_t size);
1167 
1168         /*
1169          * Fired during journal abort for dirty buffers that will not be
1170          * committed.
1171          */
1172         void (*t_abort)(struct jbd2_buffer_trigger_type *type,
1173                         struct buffer_head *bh);
1174 };
1175 
1176 extern void jbd2_buffer_frozen_trigger(struct journal_head *jh,
1177                                        void *mapped_data,
1178                                        struct jbd2_buffer_trigger_type *triggers);
1179 extern void jbd2_buffer_abort_trigger(struct journal_head *jh,
1180                                       struct jbd2_buffer_trigger_type *triggers);
1181 
1182 /* Buffer IO */
1183 extern int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
1184                                               struct journal_head *jh_in,
1185                                               struct buffer_head **bh_out,
1186                                               sector_t blocknr);
1187 
1188 /* Transaction locking */
1189 extern void             __wait_on_journal (journal_t *);
1190 
1191 /* Transaction cache support */
1192 extern void jbd2_journal_destroy_transaction_cache(void);
1193 extern int  jbd2_journal_init_transaction_cache(void);
1194 extern void jbd2_journal_free_transaction(transaction_t *);
1195 
1196 /*
1197  * Journal locking.
1198  *
1199  * We need to lock the journal during transaction state changes so that nobody
1200  * ever tries to take a handle on the running transaction while we are in the
1201  * middle of moving it to the commit phase.  j_state_lock does this.
1202  *
1203  * Note that the locking is completely interrupt unsafe.  We never touch
1204  * journal structures from interrupts.
1205  */
1206 
1207 static inline handle_t *journal_current_handle(void)
1208 {
1209         return current->journal_info;
1210 }
1211 
1212 /* The journaling code user interface:
1213  *
1214  * Create and destroy handles
1215  * Register buffer modifications against the current transaction.
1216  */
1217 
1218 extern handle_t *jbd2_journal_start(journal_t *, int nblocks);
1219 extern handle_t *jbd2__journal_start(journal_t *, int blocks, int rsv_blocks,
1220                                      gfp_t gfp_mask, unsigned int type,
1221                                      unsigned int line_no);
1222 extern int       jbd2_journal_restart(handle_t *, int nblocks);
1223 extern int       jbd2__journal_restart(handle_t *, int nblocks, gfp_t gfp_mask);
1224 extern int       jbd2_journal_start_reserved(handle_t *handle,
1225                                 unsigned int type, unsigned int line_no);
1226 extern void      jbd2_journal_free_reserved(handle_t *handle);
1227 extern int       jbd2_journal_extend (handle_t *, int nblocks);
1228 extern int       jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
1229 extern int       jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
1230 extern int       jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
1231 void             jbd2_journal_set_triggers(struct buffer_head *,
1232                                            struct jbd2_buffer_trigger_type *type);
1233 extern int       jbd2_journal_dirty_metadata (handle_t *, struct buffer_head *);
1234 extern int       jbd2_journal_forget (handle_t *, struct buffer_head *);
1235 extern void      journal_sync_buffer (struct buffer_head *);
1236 extern int       jbd2_journal_invalidatepage(journal_t *,
1237                                 struct page *, unsigned int, unsigned int);
1238 extern int       jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
1239 extern int       jbd2_journal_stop(handle_t *);
1240 extern int       jbd2_journal_flush (journal_t *);
1241 extern void      jbd2_journal_lock_updates (journal_t *);
1242 extern void      jbd2_journal_unlock_updates (journal_t *);
1243 
1244 extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1245                                 struct block_device *fs_dev,
1246                                 unsigned long long start, int len, int bsize);
1247 extern journal_t * jbd2_journal_init_inode (struct inode *);
1248 extern int         jbd2_journal_update_format (journal_t *);
1249 extern int         jbd2_journal_check_used_features
1250                    (journal_t *, unsigned long, unsigned long, unsigned long);
1251 extern int         jbd2_journal_check_available_features
1252                    (journal_t *, unsigned long, unsigned long, unsigned long);
1253 extern int         jbd2_journal_set_features
1254                    (journal_t *, unsigned long, unsigned long, unsigned long);
1255 extern void        jbd2_journal_clear_features
1256                    (journal_t *, unsigned long, unsigned long, unsigned long);
1257 extern int         jbd2_journal_load       (journal_t *journal);
1258 extern int         jbd2_journal_destroy    (journal_t *);
1259 extern int         jbd2_journal_recover    (journal_t *journal);
1260 extern int         jbd2_journal_wipe       (journal_t *, int);
1261 extern int         jbd2_journal_skip_recovery   (journal_t *);
1262 extern void        jbd2_journal_update_sb_errno(journal_t *);
1263 extern int         jbd2_journal_update_sb_log_tail      (journal_t *, tid_t,
1264                                 unsigned long, int);
1265 extern void        __jbd2_journal_abort_hard    (journal_t *);
1266 extern void        jbd2_journal_abort      (journal_t *, int);
1267 extern int         jbd2_journal_errno      (journal_t *);
1268 extern void        jbd2_journal_ack_err    (journal_t *);
1269 extern int         jbd2_journal_clear_err  (journal_t *);
1270 extern int         jbd2_journal_bmap(journal_t *, unsigned long, unsigned long long *);
1271 extern int         jbd2_journal_force_commit(journal_t *);
1272 extern int         jbd2_journal_force_commit_nested(journal_t *);
1273 extern int         jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *inode);
1274 extern int         jbd2_journal_begin_ordered_truncate(journal_t *journal,
1275                                 struct jbd2_inode *inode, loff_t new_size);
1276 extern void        jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);
1277 extern void        jbd2_journal_release_jbd_inode(journal_t *journal, struct jbd2_inode *jinode);
1278 
1279 /*
1280  * journal_head management
1281  */
1282 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh);
1283 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh);
1284 void jbd2_journal_put_journal_head(struct journal_head *jh);
1285 
1286 /*
1287  * handle management
1288  */
1289 extern struct kmem_cache *jbd2_handle_cache;
1290 
1291 static inline handle_t *jbd2_alloc_handle(gfp_t gfp_flags)
1292 {
1293         return kmem_cache_zalloc(jbd2_handle_cache, gfp_flags);
1294 }
1295 
1296 static inline void jbd2_free_handle(handle_t *handle)
1297 {
1298         kmem_cache_free(jbd2_handle_cache, handle);
1299 }
1300 
1301 /*
1302  * jbd2_inode management (optional, for those file systems that want to use
1303  * dynamically allocated jbd2_inode structures)
1304  */
1305 extern struct kmem_cache *jbd2_inode_cache;
1306 
1307 static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags)
1308 {
1309         return kmem_cache_alloc(jbd2_inode_cache, gfp_flags);
1310 }
1311 
1312 static inline void jbd2_free_inode(struct jbd2_inode *jinode)
1313 {
1314         kmem_cache_free(jbd2_inode_cache, jinode);
1315 }
1316 
1317 /* Primary revoke support */
1318 #define JOURNAL_REVOKE_DEFAULT_HASH 256
1319 extern int         jbd2_journal_init_revoke(journal_t *, int);
1320 extern void        jbd2_journal_destroy_revoke_caches(void);
1321 extern int         jbd2_journal_init_revoke_caches(void);
1322 
1323 extern void        jbd2_journal_destroy_revoke(journal_t *);
1324 extern int         jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *);
1325 extern int         jbd2_journal_cancel_revoke(handle_t *, struct journal_head *);
1326 extern void        jbd2_journal_write_revoke_records(transaction_t *transaction,
1327                                                      struct list_head *log_bufs);
1328 
1329 /* Recovery revoke support */
1330 extern int      jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t);
1331 extern int      jbd2_journal_test_revoke(journal_t *, unsigned long long, tid_t);
1332 extern void     jbd2_journal_clear_revoke(journal_t *);
1333 extern void     jbd2_journal_switch_revoke_table(journal_t *journal);
1334 extern void     jbd2_clear_buffer_revoked_flags(journal_t *journal);
1335 
1336 /*
1337  * The log thread user interface:
1338  *
1339  * Request space in the current transaction, and force transaction commit
1340  * transitions on demand.
1341  */
1342 
1343 int jbd2_log_start_commit(journal_t *journal, tid_t tid);
1344 int __jbd2_log_start_commit(journal_t *journal, tid_t tid);
1345 int jbd2_journal_start_commit(journal_t *journal, tid_t *tid);
1346 int jbd2_log_wait_commit(journal_t *journal, tid_t tid);
1347 int jbd2_complete_transaction(journal_t *journal, tid_t tid);
1348 int jbd2_log_do_checkpoint(journal_t *journal);
1349 int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid);
1350 
1351 void __jbd2_log_wait_for_space(journal_t *journal);
1352 extern void __jbd2_journal_drop_transaction(journal_t *, transaction_t *);
1353 extern int jbd2_cleanup_journal_tail(journal_t *);
1354 
1355 /*
1356  * is_journal_abort
1357  *
1358  * Simple test wrapper function to test the JBD2_ABORT state flag.  This
1359  * bit, when set, indicates that we have had a fatal error somewhere,
1360  * either inside the journaling layer or indicated to us by the client
1361  * (eg. ext3), and that we and should not commit any further
1362  * transactions.
1363  */
1364 
1365 static inline int is_journal_aborted(journal_t *journal)
1366 {
1367         return journal->j_flags & JBD2_ABORT;
1368 }
1369 
1370 static inline int is_handle_aborted(handle_t *handle)
1371 {
1372         if (handle->h_aborted || !handle->h_transaction)
1373                 return 1;
1374         return is_journal_aborted(handle->h_transaction->t_journal);
1375 }
1376 
1377 static inline void jbd2_journal_abort_handle(handle_t *handle)
1378 {
1379         handle->h_aborted = 1;
1380 }
1381 
1382 #endif /* __KERNEL__   */
1383 
1384 /* Comparison functions for transaction IDs: perform comparisons using
1385  * modulo arithmetic so that they work over sequence number wraps. */
1386 
1387 static inline int tid_gt(tid_t x, tid_t y)
1388 {
1389         int difference = (x - y);
1390         return (difference > 0);
1391 }
1392 
1393 static inline int tid_geq(tid_t x, tid_t y)
1394 {
1395         int difference = (x - y);
1396         return (difference >= 0);
1397 }
1398 
1399 extern int jbd2_journal_blocks_per_page(struct inode *inode);
1400 extern size_t journal_tag_bytes(journal_t *journal);
1401 
1402 static inline bool jbd2_journal_has_csum_v2or3_feature(journal_t *j)
1403 {
1404         return jbd2_has_feature_csum2(j) || jbd2_has_feature_csum3(j);
1405 }
1406 
1407 static inline int jbd2_journal_has_csum_v2or3(journal_t *journal)
1408 {
1409         WARN_ON_ONCE(jbd2_journal_has_csum_v2or3_feature(journal) &&
1410                      journal->j_chksum_driver == NULL);
1411 
1412         return journal->j_chksum_driver != NULL;
1413 }
1414 
1415 /*
1416  * We reserve t_outstanding_credits >> JBD2_CONTROL_BLOCKS_SHIFT for
1417  * transaction control blocks.
1418  */
1419 #define JBD2_CONTROL_BLOCKS_SHIFT 5
1420 
1421 /*
1422  * Return the minimum number of blocks which must be free in the journal
1423  * before a new transaction may be started.  Must be called under j_state_lock.
1424  */
1425 static inline int jbd2_space_needed(journal_t *journal)
1426 {
1427         int nblocks = journal->j_max_transaction_buffers;
1428         return nblocks + (nblocks >> JBD2_CONTROL_BLOCKS_SHIFT);
1429 }
1430 
1431 /*
1432  * Return number of free blocks in the log. Must be called under j_state_lock.
1433  */
1434 static inline unsigned long jbd2_log_space_left(journal_t *journal)
1435 {
1436         /* Allow for rounding errors */
1437         unsigned long free = journal->j_free - 32;
1438 
1439         if (journal->j_committing_transaction) {
1440                 unsigned long committing = atomic_read(&journal->
1441                         j_committing_transaction->t_outstanding_credits);
1442 
1443                 /* Transaction + control blocks */
1444                 free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT);
1445         }
1446         return free;
1447 }
1448 
1449 /*
1450  * Definitions which augment the buffer_head layer
1451  */
1452 
1453 /* journaling buffer types */
1454 #define BJ_None         0       /* Not journaled */
1455 #define BJ_Metadata     1       /* Normal journaled metadata */
1456 #define BJ_Forget       2       /* Buffer superseded by this transaction */
1457 #define BJ_Shadow       3       /* Buffer contents being shadowed to the log */
1458 #define BJ_Reserved     4       /* Buffer is reserved for access by journal */
1459 #define BJ_Types        5
1460 
1461 extern int jbd_blocks_per_page(struct inode *inode);
1462 
1463 /* JBD uses a CRC32 checksum */
1464 #define JBD_MAX_CHECKSUM_SIZE 4
1465 
1466 static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
1467                               const void *address, unsigned int length)
1468 {
1469         struct {
1470                 struct shash_desc shash;
1471                 char ctx[JBD_MAX_CHECKSUM_SIZE];
1472         } desc;
1473         int err;
1474 
1475         BUG_ON(crypto_shash_descsize(journal->j_chksum_driver) >
1476                 JBD_MAX_CHECKSUM_SIZE);
1477 
1478         desc.shash.tfm = journal->j_chksum_driver;
1479         desc.shash.flags = 0;
1480         *(u32 *)desc.ctx = crc;
1481 
1482         err = crypto_shash_update(&desc.shash, address, length);
1483         BUG_ON(err);
1484 
1485         return *(u32 *)desc.ctx;
1486 }
1487 
1488 /* Return most recent uncommitted transaction */
1489 static inline tid_t  jbd2_get_latest_transaction(journal_t *journal)
1490 {
1491         tid_t tid;
1492 
1493         read_lock(&journal->j_state_lock);
1494         tid = journal->j_commit_request;
1495         if (journal->j_running_transaction)
1496                 tid = journal->j_running_transaction->t_tid;
1497         read_unlock(&journal->j_state_lock);
1498         return tid;
1499 }
1500 
1501 #ifdef __KERNEL__
1502 
1503 #define buffer_trace_init(bh)   do {} while (0)
1504 #define print_buffer_fields(bh) do {} while (0)
1505 #define print_buffer_trace(bh)  do {} while (0)
1506 #define BUFFER_TRACE(bh, info)  do {} while (0)
1507 #define BUFFER_TRACE2(bh, bh2, info)    do {} while (0)
1508 #define JBUFFER_TRACE(jh, info) do {} while (0)
1509 
1510 #endif  /* __KERNEL__ */
1511 
1512 #define EFSBADCRC       EBADMSG         /* Bad CRC detected */
1513 #define EFSCORRUPTED    EUCLEAN         /* Filesystem is corrupted */
1514 
1515 #endif  /* _LINUX_JBD2_H */
1516 

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