linux/fs/jbd2/commit.c
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   1/*
   2 * linux/fs/jbd2/commit.c
   3 *
   4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
   5 *
   6 * Copyright 1998 Red Hat corp --- 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 * Journal commit routines for the generic filesystem journaling code;
  13 * part of the ext2fs journaling system.
  14 */
  15
  16#include <linux/time.h>
  17#include <linux/fs.h>
  18#include <linux/jbd2.h>
  19#include <linux/errno.h>
  20#include <linux/slab.h>
  21#include <linux/mm.h>
  22#include <linux/pagemap.h>
  23#include <linux/jiffies.h>
  24#include <linux/crc32.h>
  25#include <linux/writeback.h>
  26#include <linux/backing-dev.h>
  27#include <linux/bio.h>
  28#include <linux/blkdev.h>
  29#include <linux/bitops.h>
  30#include <trace/events/jbd2.h>
  31
  32/*
  33 * IO end handler for temporary buffer_heads handling writes to the journal.
  34 */
  35static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
  36{
  37        struct buffer_head *orig_bh = bh->b_private;
  38
  39        BUFFER_TRACE(bh, "");
  40        if (uptodate)
  41                set_buffer_uptodate(bh);
  42        else
  43                clear_buffer_uptodate(bh);
  44        if (orig_bh) {
  45                clear_bit_unlock(BH_Shadow, &orig_bh->b_state);
  46                smp_mb__after_clear_bit();
  47                wake_up_bit(&orig_bh->b_state, BH_Shadow);
  48        }
  49        unlock_buffer(bh);
  50}
  51
  52/*
  53 * When an ext4 file is truncated, it is possible that some pages are not
  54 * successfully freed, because they are attached to a committing transaction.
  55 * After the transaction commits, these pages are left on the LRU, with no
  56 * ->mapping, and with attached buffers.  These pages are trivially reclaimable
  57 * by the VM, but their apparent absence upsets the VM accounting, and it makes
  58 * the numbers in /proc/meminfo look odd.
  59 *
  60 * So here, we have a buffer which has just come off the forget list.  Look to
  61 * see if we can strip all buffers from the backing page.
  62 *
  63 * Called under lock_journal(), and possibly under journal_datalist_lock.  The
  64 * caller provided us with a ref against the buffer, and we drop that here.
  65 */
  66static void release_buffer_page(struct buffer_head *bh)
  67{
  68        struct page *page;
  69
  70        if (buffer_dirty(bh))
  71                goto nope;
  72        if (atomic_read(&bh->b_count) != 1)
  73                goto nope;
  74        page = bh->b_page;
  75        if (!page)
  76                goto nope;
  77        if (page->mapping)
  78                goto nope;
  79
  80        /* OK, it's a truncated page */
  81        if (!trylock_page(page))
  82                goto nope;
  83
  84        page_cache_get(page);
  85        __brelse(bh);
  86        try_to_free_buffers(page);
  87        unlock_page(page);
  88        page_cache_release(page);
  89        return;
  90
  91nope:
  92        __brelse(bh);
  93}
  94
  95static void jbd2_commit_block_csum_set(journal_t *j, struct buffer_head *bh)
  96{
  97        struct commit_header *h;
  98        __u32 csum;
  99
 100        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 101                return;
 102
 103        h = (struct commit_header *)(bh->b_data);
 104        h->h_chksum_type = 0;
 105        h->h_chksum_size = 0;
 106        h->h_chksum[0] = 0;
 107        csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 108        h->h_chksum[0] = cpu_to_be32(csum);
 109}
 110
 111/*
 112 * Done it all: now submit the commit record.  We should have
 113 * cleaned up our previous buffers by now, so if we are in abort
 114 * mode we can now just skip the rest of the journal write
 115 * entirely.
 116 *
 117 * Returns 1 if the journal needs to be aborted or 0 on success
 118 */
 119static int journal_submit_commit_record(journal_t *journal,
 120                                        transaction_t *commit_transaction,
 121                                        struct buffer_head **cbh,
 122                                        __u32 crc32_sum)
 123{
 124        struct commit_header *tmp;
 125        struct buffer_head *bh;
 126        int ret;
 127        struct timespec now = current_kernel_time();
 128
 129        *cbh = NULL;
 130
 131        if (is_journal_aborted(journal))
 132                return 0;
 133
 134        bh = jbd2_journal_get_descriptor_buffer(journal);
 135        if (!bh)
 136                return 1;
 137
 138        tmp = (struct commit_header *)bh->b_data;
 139        tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
 140        tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK);
 141        tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
 142        tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
 143        tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
 144
 145        if (JBD2_HAS_COMPAT_FEATURE(journal,
 146                                    JBD2_FEATURE_COMPAT_CHECKSUM)) {
 147                tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
 148                tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
 149                tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
 150        }
 151        jbd2_commit_block_csum_set(journal, bh);
 152
 153        BUFFER_TRACE(bh, "submit commit block");
 154        lock_buffer(bh);
 155        clear_buffer_dirty(bh);
 156        set_buffer_uptodate(bh);
 157        bh->b_end_io = journal_end_buffer_io_sync;
 158
 159        if (journal->j_flags & JBD2_BARRIER &&
 160            !JBD2_HAS_INCOMPAT_FEATURE(journal,
 161                                       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT))
 162                ret = submit_bh(WRITE_SYNC | WRITE_FLUSH_FUA, bh);
 163        else
 164                ret = submit_bh(WRITE_SYNC, bh);
 165
 166        *cbh = bh;
 167        return ret;
 168}
 169
 170/*
 171 * This function along with journal_submit_commit_record
 172 * allows to write the commit record asynchronously.
 173 */
 174static int journal_wait_on_commit_record(journal_t *journal,
 175                                         struct buffer_head *bh)
 176{
 177        int ret = 0;
 178
 179        clear_buffer_dirty(bh);
 180        wait_on_buffer(bh);
 181
 182        if (unlikely(!buffer_uptodate(bh)))
 183                ret = -EIO;
 184        put_bh(bh);            /* One for getblk() */
 185
 186        return ret;
 187}
 188
 189/*
 190 * write the filemap data using writepage() address_space_operations.
 191 * We don't do block allocation here even for delalloc. We don't
 192 * use writepages() because with dealyed allocation we may be doing
 193 * block allocation in writepages().
 194 */
 195static int journal_submit_inode_data_buffers(struct address_space *mapping)
 196{
 197        int ret;
 198        struct writeback_control wbc = {
 199                .sync_mode =  WB_SYNC_ALL,
 200                .nr_to_write = mapping->nrpages * 2,
 201                .range_start = 0,
 202                .range_end = i_size_read(mapping->host),
 203        };
 204
 205        ret = generic_writepages(mapping, &wbc);
 206        return ret;
 207}
 208
 209/*
 210 * Submit all the data buffers of inode associated with the transaction to
 211 * disk.
 212 *
 213 * We are in a committing transaction. Therefore no new inode can be added to
 214 * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently
 215 * operate on from being released while we write out pages.
 216 */
 217static int journal_submit_data_buffers(journal_t *journal,
 218                transaction_t *commit_transaction)
 219{
 220        struct jbd2_inode *jinode;
 221        int err, ret = 0;
 222        struct address_space *mapping;
 223
 224        spin_lock(&journal->j_list_lock);
 225        list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 226                mapping = jinode->i_vfs_inode->i_mapping;
 227                set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 228                spin_unlock(&journal->j_list_lock);
 229                /*
 230                 * submit the inode data buffers. We use writepage
 231                 * instead of writepages. Because writepages can do
 232                 * block allocation  with delalloc. We need to write
 233                 * only allocated blocks here.
 234                 */
 235                trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
 236                err = journal_submit_inode_data_buffers(mapping);
 237                if (!ret)
 238                        ret = err;
 239                spin_lock(&journal->j_list_lock);
 240                J_ASSERT(jinode->i_transaction == commit_transaction);
 241                clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 242                smp_mb__after_clear_bit();
 243                wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 244        }
 245        spin_unlock(&journal->j_list_lock);
 246        return ret;
 247}
 248
 249/*
 250 * Wait for data submitted for writeout, refile inodes to proper
 251 * transaction if needed.
 252 *
 253 */
 254static int journal_finish_inode_data_buffers(journal_t *journal,
 255                transaction_t *commit_transaction)
 256{
 257        struct jbd2_inode *jinode, *next_i;
 258        int err, ret = 0;
 259
 260        /* For locking, see the comment in journal_submit_data_buffers() */
 261        spin_lock(&journal->j_list_lock);
 262        list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
 263                set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 264                spin_unlock(&journal->j_list_lock);
 265                err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping);
 266                if (err) {
 267                        /*
 268                         * Because AS_EIO is cleared by
 269                         * filemap_fdatawait_range(), set it again so
 270                         * that user process can get -EIO from fsync().
 271                         */
 272                        set_bit(AS_EIO,
 273                                &jinode->i_vfs_inode->i_mapping->flags);
 274
 275                        if (!ret)
 276                                ret = err;
 277                }
 278                spin_lock(&journal->j_list_lock);
 279                clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 280                smp_mb__after_clear_bit();
 281                wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
 282        }
 283
 284        /* Now refile inode to proper lists */
 285        list_for_each_entry_safe(jinode, next_i,
 286                                 &commit_transaction->t_inode_list, i_list) {
 287                list_del(&jinode->i_list);
 288                if (jinode->i_next_transaction) {
 289                        jinode->i_transaction = jinode->i_next_transaction;
 290                        jinode->i_next_transaction = NULL;
 291                        list_add(&jinode->i_list,
 292                                &jinode->i_transaction->t_inode_list);
 293                } else {
 294                        jinode->i_transaction = NULL;
 295                }
 296        }
 297        spin_unlock(&journal->j_list_lock);
 298
 299        return ret;
 300}
 301
 302static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 303{
 304        struct page *page = bh->b_page;
 305        char *addr;
 306        __u32 checksum;
 307
 308        addr = kmap_atomic(page);
 309        checksum = crc32_be(crc32_sum,
 310                (void *)(addr + offset_in_page(bh->b_data)), bh->b_size);
 311        kunmap_atomic(addr);
 312
 313        return checksum;
 314}
 315
 316static void write_tag_block(int tag_bytes, journal_block_tag_t *tag,
 317                                   unsigned long long block)
 318{
 319        tag->t_blocknr = cpu_to_be32(block & (u32)~0);
 320        if (tag_bytes > JBD2_TAG_SIZE32)
 321                tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);
 322}
 323
 324static void jbd2_descr_block_csum_set(journal_t *j,
 325                                      struct buffer_head *bh)
 326{
 327        struct jbd2_journal_block_tail *tail;
 328        __u32 csum;
 329
 330        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 331                return;
 332
 333        tail = (struct jbd2_journal_block_tail *)(bh->b_data + j->j_blocksize -
 334                        sizeof(struct jbd2_journal_block_tail));
 335        tail->t_checksum = 0;
 336        csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 337        tail->t_checksum = cpu_to_be32(csum);
 338}
 339
 340static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 341                                    struct buffer_head *bh, __u32 sequence)
 342{
 343        struct page *page = bh->b_page;
 344        __u8 *addr;
 345        __u32 csum32;
 346
 347        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 348                return;
 349
 350        sequence = cpu_to_be32(sequence);
 351        addr = kmap_atomic(page);
 352        csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
 353                             sizeof(sequence));
 354        csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
 355                             bh->b_size);
 356        kunmap_atomic(addr);
 357
 358        /* We only have space to store the lower 16 bits of the crc32c. */
 359        tag->t_checksum = cpu_to_be16(csum32);
 360}
 361/*
 362 * jbd2_journal_commit_transaction
 363 *
 364 * The primary function for committing a transaction to the log.  This
 365 * function is called by the journal thread to begin a complete commit.
 366 */
 367void jbd2_journal_commit_transaction(journal_t *journal)
 368{
 369        struct transaction_stats_s stats;
 370        transaction_t *commit_transaction;
 371        struct journal_head *jh;
 372        struct buffer_head *descriptor;
 373        struct buffer_head **wbuf = journal->j_wbuf;
 374        int bufs;
 375        int flags;
 376        int err;
 377        unsigned long long blocknr;
 378        ktime_t start_time;
 379        u64 commit_time;
 380        char *tagp = NULL;
 381        journal_header_t *header;
 382        journal_block_tag_t *tag = NULL;
 383        int space_left = 0;
 384        int first_tag = 0;
 385        int tag_flag;
 386        int i;
 387        int tag_bytes = journal_tag_bytes(journal);
 388        struct buffer_head *cbh = NULL; /* For transactional checksums */
 389        __u32 crc32_sum = ~0;
 390        struct blk_plug plug;
 391        /* Tail of the journal */
 392        unsigned long first_block;
 393        tid_t first_tid;
 394        int update_tail;
 395        int csum_size = 0;
 396        LIST_HEAD(io_bufs);
 397        LIST_HEAD(log_bufs);
 398
 399        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 400                csum_size = sizeof(struct jbd2_journal_block_tail);
 401
 402        /*
 403         * First job: lock down the current transaction and wait for
 404         * all outstanding updates to complete.
 405         */
 406
 407        /* Do we need to erase the effects of a prior jbd2_journal_flush? */
 408        if (journal->j_flags & JBD2_FLUSHED) {
 409                jbd_debug(3, "super block updated\n");
 410                mutex_lock(&journal->j_checkpoint_mutex);
 411                /*
 412                 * We hold j_checkpoint_mutex so tail cannot change under us.
 413                 * We don't need any special data guarantees for writing sb
 414                 * since journal is empty and it is ok for write to be
 415                 * flushed only with transaction commit.
 416                 */
 417                jbd2_journal_update_sb_log_tail(journal,
 418                                                journal->j_tail_sequence,
 419                                                journal->j_tail,
 420                                                WRITE_SYNC);
 421                mutex_unlock(&journal->j_checkpoint_mutex);
 422        } else {
 423                jbd_debug(3, "superblock not updated\n");
 424        }
 425
 426        J_ASSERT(journal->j_running_transaction != NULL);
 427        J_ASSERT(journal->j_committing_transaction == NULL);
 428
 429        commit_transaction = journal->j_running_transaction;
 430
 431        trace_jbd2_start_commit(journal, commit_transaction);
 432        jbd_debug(1, "JBD2: starting commit of transaction %d\n",
 433                        commit_transaction->t_tid);
 434
 435        write_lock(&journal->j_state_lock);
 436        J_ASSERT(commit_transaction->t_state == T_RUNNING);
 437        commit_transaction->t_state = T_LOCKED;
 438
 439        trace_jbd2_commit_locking(journal, commit_transaction);
 440        stats.run.rs_wait = commit_transaction->t_max_wait;
 441        stats.run.rs_request_delay = 0;
 442        stats.run.rs_locked = jiffies;
 443        if (commit_transaction->t_requested)
 444                stats.run.rs_request_delay =
 445                        jbd2_time_diff(commit_transaction->t_requested,
 446                                       stats.run.rs_locked);
 447        stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start,
 448                                              stats.run.rs_locked);
 449
 450        spin_lock(&commit_transaction->t_handle_lock);
 451        while (atomic_read(&commit_transaction->t_updates)) {
 452                DEFINE_WAIT(wait);
 453
 454                prepare_to_wait(&journal->j_wait_updates, &wait,
 455                                        TASK_UNINTERRUPTIBLE);
 456                if (atomic_read(&commit_transaction->t_updates)) {
 457                        spin_unlock(&commit_transaction->t_handle_lock);
 458                        write_unlock(&journal->j_state_lock);
 459                        schedule();
 460                        write_lock(&journal->j_state_lock);
 461                        spin_lock(&commit_transaction->t_handle_lock);
 462                }
 463                finish_wait(&journal->j_wait_updates, &wait);
 464        }
 465        spin_unlock(&commit_transaction->t_handle_lock);
 466
 467        J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <=
 468                        journal->j_max_transaction_buffers);
 469
 470        /*
 471         * First thing we are allowed to do is to discard any remaining
 472         * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
 473         * that there are no such buffers: if a large filesystem
 474         * operation like a truncate needs to split itself over multiple
 475         * transactions, then it may try to do a jbd2_journal_restart() while
 476         * there are still BJ_Reserved buffers outstanding.  These must
 477         * be released cleanly from the current transaction.
 478         *
 479         * In this case, the filesystem must still reserve write access
 480         * again before modifying the buffer in the new transaction, but
 481         * we do not require it to remember exactly which old buffers it
 482         * has reserved.  This is consistent with the existing behaviour
 483         * that multiple jbd2_journal_get_write_access() calls to the same
 484         * buffer are perfectly permissible.
 485         */
 486        while (commit_transaction->t_reserved_list) {
 487                jh = commit_transaction->t_reserved_list;
 488                JBUFFER_TRACE(jh, "reserved, unused: refile");
 489                /*
 490                 * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may
 491                 * leave undo-committed data.
 492                 */
 493                if (jh->b_committed_data) {
 494                        struct buffer_head *bh = jh2bh(jh);
 495
 496                        jbd_lock_bh_state(bh);
 497                        jbd2_free(jh->b_committed_data, bh->b_size);
 498                        jh->b_committed_data = NULL;
 499                        jbd_unlock_bh_state(bh);
 500                }
 501                jbd2_journal_refile_buffer(journal, jh);
 502        }
 503
 504        /*
 505         * Now try to drop any written-back buffers from the journal's
 506         * checkpoint lists.  We do this *before* commit because it potentially
 507         * frees some memory
 508         */
 509        spin_lock(&journal->j_list_lock);
 510        __jbd2_journal_clean_checkpoint_list(journal);
 511        spin_unlock(&journal->j_list_lock);
 512
 513        jbd_debug(3, "JBD2: commit phase 1\n");
 514
 515        /*
 516         * Clear revoked flag to reflect there is no revoked buffers
 517         * in the next transaction which is going to be started.
 518         */
 519        jbd2_clear_buffer_revoked_flags(journal);
 520
 521        /*
 522         * Switch to a new revoke table.
 523         */
 524        jbd2_journal_switch_revoke_table(journal);
 525
 526        /*
 527         * Reserved credits cannot be claimed anymore, free them
 528         */
 529        atomic_sub(atomic_read(&journal->j_reserved_credits),
 530                   &commit_transaction->t_outstanding_credits);
 531
 532        trace_jbd2_commit_flushing(journal, commit_transaction);
 533        stats.run.rs_flushing = jiffies;
 534        stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked,
 535                                             stats.run.rs_flushing);
 536
 537        commit_transaction->t_state = T_FLUSH;
 538        journal->j_committing_transaction = commit_transaction;
 539        journal->j_running_transaction = NULL;
 540        start_time = ktime_get();
 541        commit_transaction->t_log_start = journal->j_head;
 542        wake_up(&journal->j_wait_transaction_locked);
 543        write_unlock(&journal->j_state_lock);
 544
 545        jbd_debug(3, "JBD2: commit phase 2a\n");
 546
 547        /*
 548         * Now start flushing things to disk, in the order they appear
 549         * on the transaction lists.  Data blocks go first.
 550         */
 551        err = journal_submit_data_buffers(journal, commit_transaction);
 552        if (err)
 553                jbd2_journal_abort(journal, err);
 554
 555        blk_start_plug(&plug);
 556        jbd2_journal_write_revoke_records(journal, commit_transaction,
 557                                          &log_bufs, WRITE_SYNC);
 558        blk_finish_plug(&plug);
 559
 560        jbd_debug(3, "JBD2: commit phase 2b\n");
 561
 562        /*
 563         * Way to go: we have now written out all of the data for a
 564         * transaction!  Now comes the tricky part: we need to write out
 565         * metadata.  Loop over the transaction's entire buffer list:
 566         */
 567        write_lock(&journal->j_state_lock);
 568        commit_transaction->t_state = T_COMMIT;
 569        write_unlock(&journal->j_state_lock);
 570
 571        trace_jbd2_commit_logging(journal, commit_transaction);
 572        stats.run.rs_logging = jiffies;
 573        stats.run.rs_flushing = jbd2_time_diff(stats.run.rs_flushing,
 574                                               stats.run.rs_logging);
 575        stats.run.rs_blocks =
 576                atomic_read(&commit_transaction->t_outstanding_credits);
 577        stats.run.rs_blocks_logged = 0;
 578
 579        J_ASSERT(commit_transaction->t_nr_buffers <=
 580                 atomic_read(&commit_transaction->t_outstanding_credits));
 581
 582        err = 0;
 583        bufs = 0;
 584        descriptor = NULL;
 585        blk_start_plug(&plug);
 586        while (commit_transaction->t_buffers) {
 587
 588                /* Find the next buffer to be journaled... */
 589
 590                jh = commit_transaction->t_buffers;
 591
 592                /* If we're in abort mode, we just un-journal the buffer and
 593                   release it. */
 594
 595                if (is_journal_aborted(journal)) {
 596                        clear_buffer_jbddirty(jh2bh(jh));
 597                        JBUFFER_TRACE(jh, "journal is aborting: refile");
 598                        jbd2_buffer_abort_trigger(jh,
 599                                                  jh->b_frozen_data ?
 600                                                  jh->b_frozen_triggers :
 601                                                  jh->b_triggers);
 602                        jbd2_journal_refile_buffer(journal, jh);
 603                        /* If that was the last one, we need to clean up
 604                         * any descriptor buffers which may have been
 605                         * already allocated, even if we are now
 606                         * aborting. */
 607                        if (!commit_transaction->t_buffers)
 608                                goto start_journal_io;
 609                        continue;
 610                }
 611
 612                /* Make sure we have a descriptor block in which to
 613                   record the metadata buffer. */
 614
 615                if (!descriptor) {
 616                        J_ASSERT (bufs == 0);
 617
 618                        jbd_debug(4, "JBD2: get descriptor\n");
 619
 620                        descriptor = jbd2_journal_get_descriptor_buffer(journal);
 621                        if (!descriptor) {
 622                                jbd2_journal_abort(journal, -EIO);
 623                                continue;
 624                        }
 625
 626                        jbd_debug(4, "JBD2: got buffer %llu (%p)\n",
 627                                (unsigned long long)descriptor->b_blocknr,
 628                                descriptor->b_data);
 629                        header = (journal_header_t *)descriptor->b_data;
 630                        header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
 631                        header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK);
 632                        header->h_sequence  = cpu_to_be32(commit_transaction->t_tid);
 633
 634                        tagp = &descriptor->b_data[sizeof(journal_header_t)];
 635                        space_left = descriptor->b_size -
 636                                                sizeof(journal_header_t);
 637                        first_tag = 1;
 638                        set_buffer_jwrite(descriptor);
 639                        set_buffer_dirty(descriptor);
 640                        wbuf[bufs++] = descriptor;
 641
 642                        /* Record it so that we can wait for IO
 643                           completion later */
 644                        BUFFER_TRACE(descriptor, "ph3: file as descriptor");
 645                        jbd2_file_log_bh(&log_bufs, descriptor);
 646                }
 647
 648                /* Where is the buffer to be written? */
 649
 650                err = jbd2_journal_next_log_block(journal, &blocknr);
 651                /* If the block mapping failed, just abandon the buffer
 652                   and repeat this loop: we'll fall into the
 653                   refile-on-abort condition above. */
 654                if (err) {
 655                        jbd2_journal_abort(journal, err);
 656                        continue;
 657                }
 658
 659                /*
 660                 * start_this_handle() uses t_outstanding_credits to determine
 661                 * the free space in the log, but this counter is changed
 662                 * by jbd2_journal_next_log_block() also.
 663                 */
 664                atomic_dec(&commit_transaction->t_outstanding_credits);
 665
 666                /* Bump b_count to prevent truncate from stumbling over
 667                   the shadowed buffer!  @@@ This can go if we ever get
 668                   rid of the shadow pairing of buffers. */
 669                atomic_inc(&jh2bh(jh)->b_count);
 670
 671                /*
 672                 * Make a temporary IO buffer with which to write it out
 673                 * (this will requeue the metadata buffer to BJ_Shadow).
 674                 */
 675                set_bit(BH_JWrite, &jh2bh(jh)->b_state);
 676                JBUFFER_TRACE(jh, "ph3: write metadata");
 677                flags = jbd2_journal_write_metadata_buffer(commit_transaction,
 678                                                jh, &wbuf[bufs], blocknr);
 679                if (flags < 0) {
 680                        jbd2_journal_abort(journal, flags);
 681                        continue;
 682                }
 683                jbd2_file_log_bh(&io_bufs, wbuf[bufs]);
 684
 685                /* Record the new block's tag in the current descriptor
 686                   buffer */
 687
 688                tag_flag = 0;
 689                if (flags & 1)
 690                        tag_flag |= JBD2_FLAG_ESCAPE;
 691                if (!first_tag)
 692                        tag_flag |= JBD2_FLAG_SAME_UUID;
 693
 694                tag = (journal_block_tag_t *) tagp;
 695                write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr);
 696                tag->t_flags = cpu_to_be16(tag_flag);
 697                jbd2_block_tag_csum_set(journal, tag, wbuf[bufs],
 698                                        commit_transaction->t_tid);
 699                tagp += tag_bytes;
 700                space_left -= tag_bytes;
 701                bufs++;
 702
 703                if (first_tag) {
 704                        memcpy (tagp, journal->j_uuid, 16);
 705                        tagp += 16;
 706                        space_left -= 16;
 707                        first_tag = 0;
 708                }
 709
 710                /* If there's no more to do, or if the descriptor is full,
 711                   let the IO rip! */
 712
 713                if (bufs == journal->j_wbufsize ||
 714                    commit_transaction->t_buffers == NULL ||
 715                    space_left < tag_bytes + 16 + csum_size) {
 716
 717                        jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
 718
 719                        /* Write an end-of-descriptor marker before
 720                           submitting the IOs.  "tag" still points to
 721                           the last tag we set up. */
 722
 723                        tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
 724
 725                        jbd2_descr_block_csum_set(journal, descriptor);
 726start_journal_io:
 727                        for (i = 0; i < bufs; i++) {
 728                                struct buffer_head *bh = wbuf[i];
 729                                /*
 730                                 * Compute checksum.
 731                                 */
 732                                if (JBD2_HAS_COMPAT_FEATURE(journal,
 733                                        JBD2_FEATURE_COMPAT_CHECKSUM)) {
 734                                        crc32_sum =
 735                                            jbd2_checksum_data(crc32_sum, bh);
 736                                }
 737
 738                                lock_buffer(bh);
 739                                clear_buffer_dirty(bh);
 740                                set_buffer_uptodate(bh);
 741                                bh->b_end_io = journal_end_buffer_io_sync;
 742                                submit_bh(WRITE_SYNC, bh);
 743                        }
 744                        cond_resched();
 745                        stats.run.rs_blocks_logged += bufs;
 746
 747                        /* Force a new descriptor to be generated next
 748                           time round the loop. */
 749                        descriptor = NULL;
 750                        bufs = 0;
 751                }
 752        }
 753
 754        err = journal_finish_inode_data_buffers(journal, commit_transaction);
 755        if (err) {
 756                printk(KERN_WARNING
 757                        "JBD2: Detected IO errors while flushing file data "
 758                       "on %s\n", journal->j_devname);
 759                if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
 760                        jbd2_journal_abort(journal, err);
 761                err = 0;
 762        }
 763
 764        /*
 765         * Get current oldest transaction in the log before we issue flush
 766         * to the filesystem device. After the flush we can be sure that
 767         * blocks of all older transactions are checkpointed to persistent
 768         * storage and we will be safe to update journal start in the
 769         * superblock with the numbers we get here.
 770         */
 771        update_tail =
 772                jbd2_journal_get_log_tail(journal, &first_tid, &first_block);
 773
 774        write_lock(&journal->j_state_lock);
 775        if (update_tail) {
 776                long freed = first_block - journal->j_tail;
 777
 778                if (first_block < journal->j_tail)
 779                        freed += journal->j_last - journal->j_first;
 780                /* Update tail only if we free significant amount of space */
 781                if (freed < journal->j_maxlen / 4)
 782                        update_tail = 0;
 783        }
 784        J_ASSERT(commit_transaction->t_state == T_COMMIT);
 785        commit_transaction->t_state = T_COMMIT_DFLUSH;
 786        write_unlock(&journal->j_state_lock);
 787
 788        /* 
 789         * If the journal is not located on the file system device,
 790         * then we must flush the file system device before we issue
 791         * the commit record
 792         */
 793        if (commit_transaction->t_need_data_flush &&
 794            (journal->j_fs_dev != journal->j_dev) &&
 795            (journal->j_flags & JBD2_BARRIER))
 796                blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 797
 798        /* Done it all: now write the commit record asynchronously. */
 799        if (JBD2_HAS_INCOMPAT_FEATURE(journal,
 800                                      JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 801                err = journal_submit_commit_record(journal, commit_transaction,
 802                                                 &cbh, crc32_sum);
 803                if (err)
 804                        __jbd2_journal_abort_hard(journal);
 805        }
 806
 807        blk_finish_plug(&plug);
 808
 809        /* Lo and behold: we have just managed to send a transaction to
 810           the log.  Before we can commit it, wait for the IO so far to
 811           complete.  Control buffers being written are on the
 812           transaction's t_log_list queue, and metadata buffers are on
 813           the io_bufs list.
 814
 815           Wait for the buffers in reverse order.  That way we are
 816           less likely to be woken up until all IOs have completed, and
 817           so we incur less scheduling load.
 818        */
 819
 820        jbd_debug(3, "JBD2: commit phase 3\n");
 821
 822        while (!list_empty(&io_bufs)) {
 823                struct buffer_head *bh = list_entry(io_bufs.prev,
 824                                                    struct buffer_head,
 825                                                    b_assoc_buffers);
 826
 827                wait_on_buffer(bh);
 828                cond_resched();
 829
 830                if (unlikely(!buffer_uptodate(bh)))
 831                        err = -EIO;
 832                jbd2_unfile_log_bh(bh);
 833
 834                /*
 835                 * The list contains temporary buffer heads created by
 836                 * jbd2_journal_write_metadata_buffer().
 837                 */
 838                BUFFER_TRACE(bh, "dumping temporary bh");
 839                __brelse(bh);
 840                J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
 841                free_buffer_head(bh);
 842
 843                /* We also have to refile the corresponding shadowed buffer */
 844                jh = commit_transaction->t_shadow_list->b_tprev;
 845                bh = jh2bh(jh);
 846                clear_buffer_jwrite(bh);
 847                J_ASSERT_BH(bh, buffer_jbddirty(bh));
 848                J_ASSERT_BH(bh, !buffer_shadow(bh));
 849
 850                /* The metadata is now released for reuse, but we need
 851                   to remember it against this transaction so that when
 852                   we finally commit, we can do any checkpointing
 853                   required. */
 854                JBUFFER_TRACE(jh, "file as BJ_Forget");
 855                jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget);
 856                JBUFFER_TRACE(jh, "brelse shadowed buffer");
 857                __brelse(bh);
 858        }
 859
 860        J_ASSERT (commit_transaction->t_shadow_list == NULL);
 861
 862        jbd_debug(3, "JBD2: commit phase 4\n");
 863
 864        /* Here we wait for the revoke record and descriptor record buffers */
 865        while (!list_empty(&log_bufs)) {
 866                struct buffer_head *bh;
 867
 868                bh = list_entry(log_bufs.prev, struct buffer_head, b_assoc_buffers);
 869                wait_on_buffer(bh);
 870                cond_resched();
 871
 872                if (unlikely(!buffer_uptodate(bh)))
 873                        err = -EIO;
 874
 875                BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
 876                clear_buffer_jwrite(bh);
 877                jbd2_unfile_log_bh(bh);
 878                __brelse(bh);           /* One for getblk */
 879                /* AKPM: bforget here */
 880        }
 881
 882        if (err)
 883                jbd2_journal_abort(journal, err);
 884
 885        jbd_debug(3, "JBD2: commit phase 5\n");
 886        write_lock(&journal->j_state_lock);
 887        J_ASSERT(commit_transaction->t_state == T_COMMIT_DFLUSH);
 888        commit_transaction->t_state = T_COMMIT_JFLUSH;
 889        write_unlock(&journal->j_state_lock);
 890
 891        if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
 892                                       JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 893                err = journal_submit_commit_record(journal, commit_transaction,
 894                                                &cbh, crc32_sum);
 895                if (err)
 896                        __jbd2_journal_abort_hard(journal);
 897        }
 898        if (cbh)
 899                err = journal_wait_on_commit_record(journal, cbh);
 900        if (JBD2_HAS_INCOMPAT_FEATURE(journal,
 901                                      JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT) &&
 902            journal->j_flags & JBD2_BARRIER) {
 903                blkdev_issue_flush(journal->j_dev, GFP_NOFS, NULL);
 904        }
 905
 906        if (err)
 907                jbd2_journal_abort(journal, err);
 908
 909        /*
 910         * Now disk caches for filesystem device are flushed so we are safe to
 911         * erase checkpointed transactions from the log by updating journal
 912         * superblock.
 913         */
 914        if (update_tail)
 915                jbd2_update_log_tail(journal, first_tid, first_block);
 916
 917        /* End of a transaction!  Finally, we can do checkpoint
 918           processing: any buffers committed as a result of this
 919           transaction can be removed from any checkpoint list it was on
 920           before. */
 921
 922        jbd_debug(3, "JBD2: commit phase 6\n");
 923
 924        J_ASSERT(list_empty(&commit_transaction->t_inode_list));
 925        J_ASSERT(commit_transaction->t_buffers == NULL);
 926        J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
 927        J_ASSERT(commit_transaction->t_shadow_list == NULL);
 928
 929restart_loop:
 930        /*
 931         * As there are other places (journal_unmap_buffer()) adding buffers
 932         * to this list we have to be careful and hold the j_list_lock.
 933         */
 934        spin_lock(&journal->j_list_lock);
 935        while (commit_transaction->t_forget) {
 936                transaction_t *cp_transaction;
 937                struct buffer_head *bh;
 938                int try_to_free = 0;
 939
 940                jh = commit_transaction->t_forget;
 941                spin_unlock(&journal->j_list_lock);
 942                bh = jh2bh(jh);
 943                /*
 944                 * Get a reference so that bh cannot be freed before we are
 945                 * done with it.
 946                 */
 947                get_bh(bh);
 948                jbd_lock_bh_state(bh);
 949                J_ASSERT_JH(jh, jh->b_transaction == commit_transaction);
 950
 951                /*
 952                 * If there is undo-protected committed data against
 953                 * this buffer, then we can remove it now.  If it is a
 954                 * buffer needing such protection, the old frozen_data
 955                 * field now points to a committed version of the
 956                 * buffer, so rotate that field to the new committed
 957                 * data.
 958                 *
 959                 * Otherwise, we can just throw away the frozen data now.
 960                 *
 961                 * We also know that the frozen data has already fired
 962                 * its triggers if they exist, so we can clear that too.
 963                 */
 964                if (jh->b_committed_data) {
 965                        jbd2_free(jh->b_committed_data, bh->b_size);
 966                        jh->b_committed_data = NULL;
 967                        if (jh->b_frozen_data) {
 968                                jh->b_committed_data = jh->b_frozen_data;
 969                                jh->b_frozen_data = NULL;
 970                                jh->b_frozen_triggers = NULL;
 971                        }
 972                } else if (jh->b_frozen_data) {
 973                        jbd2_free(jh->b_frozen_data, bh->b_size);
 974                        jh->b_frozen_data = NULL;
 975                        jh->b_frozen_triggers = NULL;
 976                }
 977
 978                spin_lock(&journal->j_list_lock);
 979                cp_transaction = jh->b_cp_transaction;
 980                if (cp_transaction) {
 981                        JBUFFER_TRACE(jh, "remove from old cp transaction");
 982                        cp_transaction->t_chp_stats.cs_dropped++;
 983                        __jbd2_journal_remove_checkpoint(jh);
 984                }
 985
 986                /* Only re-checkpoint the buffer_head if it is marked
 987                 * dirty.  If the buffer was added to the BJ_Forget list
 988                 * by jbd2_journal_forget, it may no longer be dirty and
 989                 * there's no point in keeping a checkpoint record for
 990                 * it. */
 991
 992                /*
 993                * A buffer which has been freed while still being journaled by
 994                * a previous transaction.
 995                */
 996                if (buffer_freed(bh)) {
 997                        /*
 998                         * If the running transaction is the one containing
 999                         * "add to orphan" operation (b_next_transaction !=
1000                         * NULL), we have to wait for that transaction to
1001                         * commit before we can really get rid of the buffer.
1002                         * So just clear b_modified to not confuse transaction
1003                         * credit accounting and refile the buffer to
1004                         * BJ_Forget of the running transaction. If the just
1005                         * committed transaction contains "add to orphan"
1006                         * operation, we can completely invalidate the buffer
1007                         * now. We are rather through in that since the
1008                         * buffer may be still accessible when blocksize <
1009                         * pagesize and it is attached to the last partial
1010                         * page.
1011                         */
1012                        jh->b_modified = 0;
1013                        if (!jh->b_next_transaction) {
1014                                clear_buffer_freed(bh);
1015                                clear_buffer_jbddirty(bh);
1016                                clear_buffer_mapped(bh);
1017                                clear_buffer_new(bh);
1018                                clear_buffer_req(bh);
1019                                bh->b_bdev = NULL;
1020                        }
1021                }
1022
1023                if (buffer_jbddirty(bh)) {
1024                        JBUFFER_TRACE(jh, "add to new checkpointing trans");
1025                        __jbd2_journal_insert_checkpoint(jh, commit_transaction);
1026                        if (is_journal_aborted(journal))
1027                                clear_buffer_jbddirty(bh);
1028                } else {
1029                        J_ASSERT_BH(bh, !buffer_dirty(bh));
1030                        /*
1031                         * The buffer on BJ_Forget list and not jbddirty means
1032                         * it has been freed by this transaction and hence it
1033                         * could not have been reallocated until this
1034                         * transaction has committed. *BUT* it could be
1035                         * reallocated once we have written all the data to
1036                         * disk and before we process the buffer on BJ_Forget
1037                         * list.
1038                         */
1039                        if (!jh->b_next_transaction)
1040                                try_to_free = 1;
1041                }
1042                JBUFFER_TRACE(jh, "refile or unfile buffer");
1043                __jbd2_journal_refile_buffer(jh);
1044                jbd_unlock_bh_state(bh);
1045                if (try_to_free)
1046                        release_buffer_page(bh);        /* Drops bh reference */
1047                else
1048                        __brelse(bh);
1049                cond_resched_lock(&journal->j_list_lock);
1050        }
1051        spin_unlock(&journal->j_list_lock);
1052        /*
1053         * This is a bit sleazy.  We use j_list_lock to protect transition
1054         * of a transaction into T_FINISHED state and calling
1055         * __jbd2_journal_drop_transaction(). Otherwise we could race with
1056         * other checkpointing code processing the transaction...
1057         */
1058        write_lock(&journal->j_state_lock);
1059        spin_lock(&journal->j_list_lock);
1060        /*
1061         * Now recheck if some buffers did not get attached to the transaction
1062         * while the lock was dropped...
1063         */
1064        if (commit_transaction->t_forget) {
1065                spin_unlock(&journal->j_list_lock);
1066                write_unlock(&journal->j_state_lock);
1067                goto restart_loop;
1068        }
1069
1070        /* Done with this transaction! */
1071
1072        jbd_debug(3, "JBD2: commit phase 7\n");
1073
1074        J_ASSERT(commit_transaction->t_state == T_COMMIT_JFLUSH);
1075
1076        commit_transaction->t_start = jiffies;
1077        stats.run.rs_logging = jbd2_time_diff(stats.run.rs_logging,
1078                                              commit_transaction->t_start);
1079
1080        /*
1081         * File the transaction statistics
1082         */
1083        stats.ts_tid = commit_transaction->t_tid;
1084        stats.run.rs_handle_count =
1085                atomic_read(&commit_transaction->t_handle_count);
1086        trace_jbd2_run_stats(journal->j_fs_dev->bd_dev,
1087                             commit_transaction->t_tid, &stats.run);
1088
1089        /*
1090         * Calculate overall stats
1091         */
1092        spin_lock(&journal->j_history_lock);
1093        journal->j_stats.ts_tid++;
1094        if (commit_transaction->t_requested)
1095                journal->j_stats.ts_requested++;
1096        journal->j_stats.run.rs_wait += stats.run.rs_wait;
1097        journal->j_stats.run.rs_request_delay += stats.run.rs_request_delay;
1098        journal->j_stats.run.rs_running += stats.run.rs_running;
1099        journal->j_stats.run.rs_locked += stats.run.rs_locked;
1100        journal->j_stats.run.rs_flushing += stats.run.rs_flushing;
1101        journal->j_stats.run.rs_logging += stats.run.rs_logging;
1102        journal->j_stats.run.rs_handle_count += stats.run.rs_handle_count;
1103        journal->j_stats.run.rs_blocks += stats.run.rs_blocks;
1104        journal->j_stats.run.rs_blocks_logged += stats.run.rs_blocks_logged;
1105        spin_unlock(&journal->j_history_lock);
1106
1107        commit_transaction->t_state = T_COMMIT_CALLBACK;
1108        J_ASSERT(commit_transaction == journal->j_committing_transaction);
1109        journal->j_commit_sequence = commit_transaction->t_tid;
1110        journal->j_committing_transaction = NULL;
1111        commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
1112
1113        /*
1114         * weight the commit time higher than the average time so we don't
1115         * react too strongly to vast changes in the commit time
1116         */
1117        if (likely(journal->j_average_commit_time))
1118                journal->j_average_commit_time = (commit_time +
1119                                journal->j_average_commit_time*3) / 4;
1120        else
1121                journal->j_average_commit_time = commit_time;
1122
1123        write_unlock(&journal->j_state_lock);
1124
1125        if (journal->j_checkpoint_transactions == NULL) {
1126                journal->j_checkpoint_transactions = commit_transaction;
1127                commit_transaction->t_cpnext = commit_transaction;
1128                commit_transaction->t_cpprev = commit_transaction;
1129        } else {
1130                commit_transaction->t_cpnext =
1131                        journal->j_checkpoint_transactions;
1132                commit_transaction->t_cpprev =
1133                        commit_transaction->t_cpnext->t_cpprev;
1134                commit_transaction->t_cpnext->t_cpprev =
1135                        commit_transaction;
1136                commit_transaction->t_cpprev->t_cpnext =
1137                                commit_transaction;
1138        }
1139        spin_unlock(&journal->j_list_lock);
1140        /* Drop all spin_locks because commit_callback may be block.
1141         * __journal_remove_checkpoint() can not destroy transaction
1142         * under us because it is not marked as T_FINISHED yet */
1143        if (journal->j_commit_callback)
1144                journal->j_commit_callback(journal, commit_transaction);
1145
1146        trace_jbd2_end_commit(journal, commit_transaction);
1147        jbd_debug(1, "JBD2: commit %d complete, head %d\n",
1148                  journal->j_commit_sequence, journal->j_tail_sequence);
1149
1150        write_lock(&journal->j_state_lock);
1151        spin_lock(&journal->j_list_lock);
1152        commit_transaction->t_state = T_FINISHED;
1153        /* Recheck checkpoint lists after j_list_lock was dropped */
1154        if (commit_transaction->t_checkpoint_list == NULL &&
1155            commit_transaction->t_checkpoint_io_list == NULL) {
1156                __jbd2_journal_drop_transaction(journal, commit_transaction);
1157                jbd2_journal_free_transaction(commit_transaction);
1158        }
1159        spin_unlock(&journal->j_list_lock);
1160        write_unlock(&journal->j_state_lock);
1161        wake_up(&journal->j_wait_done_commit);
1162}
1163
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