diff options
Diffstat (limited to 'fs/jbd2/commit.c')
| -rw-r--r-- | fs/jbd2/commit.c | 920 |
1 files changed, 920 insertions, 0 deletions
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c new file mode 100644 index 000000000000..70b2ae1ef281 --- /dev/null +++ b/fs/jbd2/commit.c @@ -0,0 +1,920 @@ +/* + * linux/fs/jbd2/commit.c + * + * Written by Stephen C. Tweedie <sct@redhat.com>, 1998 + * + * Copyright 1998 Red Hat corp --- All Rights Reserved + * + * This file is part of the Linux kernel and is made available under + * the terms of the GNU General Public License, version 2, or at your + * option, any later version, incorporated herein by reference. + * + * Journal commit routines for the generic filesystem journaling code; + * part of the ext2fs journaling system. + */ + +#include <linux/time.h> +#include <linux/fs.h> +#include <linux/jbd2.h> +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/smp_lock.h> + +/* + * Default IO end handler for temporary BJ_IO buffer_heads. + */ +static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate) +{ + BUFFER_TRACE(bh, ""); + if (uptodate) + set_buffer_uptodate(bh); + else + clear_buffer_uptodate(bh); + unlock_buffer(bh); +} + +/* + * When an ext3-ordered file is truncated, it is possible that many pages are + * not sucessfully freed, because they are attached to a committing transaction. + * After the transaction commits, these pages are left on the LRU, with no + * ->mapping, and with attached buffers. These pages are trivially reclaimable + * by the VM, but their apparent absence upsets the VM accounting, and it makes + * the numbers in /proc/meminfo look odd. + * + * So here, we have a buffer which has just come off the forget list. Look to + * see if we can strip all buffers from the backing page. + * + * Called under lock_journal(), and possibly under journal_datalist_lock. The + * caller provided us with a ref against the buffer, and we drop that here. + */ +static void release_buffer_page(struct buffer_head *bh) +{ + struct page *page; + + if (buffer_dirty(bh)) + goto nope; + if (atomic_read(&bh->b_count) != 1) + goto nope; + page = bh->b_page; + if (!page) + goto nope; + if (page->mapping) + goto nope; + + /* OK, it's a truncated page */ + if (TestSetPageLocked(page)) + goto nope; + + page_cache_get(page); + __brelse(bh); + try_to_free_buffers(page); + unlock_page(page); + page_cache_release(page); + return; + +nope: + __brelse(bh); +} + +/* + * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is + * held. For ranking reasons we must trylock. If we lose, schedule away and + * return 0. j_list_lock is dropped in this case. + */ +static int inverted_lock(journal_t *journal, struct buffer_head *bh) +{ + if (!jbd_trylock_bh_state(bh)) { + spin_unlock(&journal->j_list_lock); + schedule(); + return 0; + } + return 1; +} + +/* Done it all: now write the commit record. We should have + * cleaned up our previous buffers by now, so if we are in abort + * mode we can now just skip the rest of the journal write + * entirely. + * + * Returns 1 if the journal needs to be aborted or 0 on success + */ +static int journal_write_commit_record(journal_t *journal, + transaction_t *commit_transaction) +{ + struct journal_head *descriptor; + struct buffer_head *bh; + int i, ret; + int barrier_done = 0; + + if (is_journal_aborted(journal)) + return 0; + + descriptor = jbd2_journal_get_descriptor_buffer(journal); + if (!descriptor) + return 1; + + bh = jh2bh(descriptor); + + /* AKPM: buglet - add `i' to tmp! */ + for (i = 0; i < bh->b_size; i += 512) { + journal_header_t *tmp = (journal_header_t*)bh->b_data; + tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); + tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK); + tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid); + } + + JBUFFER_TRACE(descriptor, "write commit block"); + set_buffer_dirty(bh); + if (journal->j_flags & JBD2_BARRIER) { + set_buffer_ordered(bh); + barrier_done = 1; + } + ret = sync_dirty_buffer(bh); + /* is it possible for another commit to fail at roughly + * the same time as this one? If so, we don't want to + * trust the barrier flag in the super, but instead want + * to remember if we sent a barrier request + */ + if (ret == -EOPNOTSUPP && barrier_done) { + char b[BDEVNAME_SIZE]; + + printk(KERN_WARNING + "JBD: barrier-based sync failed on %s - " + "disabling barriers\n", + bdevname(journal->j_dev, b)); + spin_lock(&journal->j_state_lock); + journal->j_flags &= ~JBD2_BARRIER; + spin_unlock(&journal->j_state_lock); + + /* And try again, without the barrier */ + clear_buffer_ordered(bh); + set_buffer_uptodate(bh); + set_buffer_dirty(bh); + ret = sync_dirty_buffer(bh); + } + put_bh(bh); /* One for getblk() */ + jbd2_journal_put_journal_head(descriptor); + + return (ret == -EIO); +} + +static void journal_do_submit_data(struct buffer_head **wbuf, int bufs) +{ + int i; + + for (i = 0; i < bufs; i++) { + wbuf[i]->b_end_io = end_buffer_write_sync; + /* We use-up our safety reference in submit_bh() */ + submit_bh(WRITE, wbuf[i]); + } +} + +/* + * Submit all the data buffers to disk + */ +static void journal_submit_data_buffers(journal_t *journal, + transaction_t *commit_transaction) +{ + struct journal_head *jh; + struct buffer_head *bh; + int locked; + int bufs = 0; + struct buffer_head **wbuf = journal->j_wbuf; + + /* + * Whenever we unlock the journal and sleep, things can get added + * onto ->t_sync_datalist, so we have to keep looping back to + * write_out_data until we *know* that the list is empty. + * + * Cleanup any flushed data buffers from the data list. Even in + * abort mode, we want to flush this out as soon as possible. + */ +write_out_data: + cond_resched(); + spin_lock(&journal->j_list_lock); + + while (commit_transaction->t_sync_datalist) { + jh = commit_transaction->t_sync_datalist; + bh = jh2bh(jh); + locked = 0; + + /* Get reference just to make sure buffer does not disappear + * when we are forced to drop various locks */ + get_bh(bh); + /* If the buffer is dirty, we need to submit IO and hence + * we need the buffer lock. We try to lock the buffer without + * blocking. If we fail, we need to drop j_list_lock and do + * blocking lock_buffer(). + */ + if (buffer_dirty(bh)) { + if (test_set_buffer_locked(bh)) { + BUFFER_TRACE(bh, "needs blocking lock"); + spin_unlock(&journal->j_list_lock); + /* Write out all data to prevent deadlocks */ + journal_do_submit_data(wbuf, bufs); + bufs = 0; + lock_buffer(bh); + spin_lock(&journal->j_list_lock); + } + locked = 1; + } + /* We have to get bh_state lock. Again out of order, sigh. */ + if (!inverted_lock(journal, bh)) { + jbd_lock_bh_state(bh); + spin_lock(&journal->j_list_lock); + } + /* Someone already cleaned up the buffer? */ + if (!buffer_jbd(bh) + || jh->b_transaction != commit_transaction + || jh->b_jlist != BJ_SyncData) { + jbd_unlock_bh_state(bh); + if (locked) + unlock_buffer(bh); + BUFFER_TRACE(bh, "already cleaned up"); + put_bh(bh); + continue; + } + if (locked && test_clear_buffer_dirty(bh)) { + BUFFER_TRACE(bh, "needs writeout, adding to array"); + wbuf[bufs++] = bh; + __jbd2_journal_file_buffer(jh, commit_transaction, + BJ_Locked); + jbd_unlock_bh_state(bh); + if (bufs == journal->j_wbufsize) { + spin_unlock(&journal->j_list_lock); + journal_do_submit_data(wbuf, bufs); + bufs = 0; + goto write_out_data; + } + } + else { + BUFFER_TRACE(bh, "writeout complete: unfile"); + __jbd2_journal_unfile_buffer(jh); + jbd_unlock_bh_state(bh); + if (locked) + unlock_buffer(bh); + jbd2_journal_remove_journal_head(bh); + /* Once for our safety reference, once for + * jbd2_journal_remove_journal_head() */ + put_bh(bh); + put_bh(bh); + } + + if (lock_need_resched(&journal->j_list_lock)) { + spin_unlock(&journal->j_list_lock); + goto write_out_data; + } + } + spin_unlock(&journal->j_list_lock); + journal_do_submit_data(wbuf, bufs); +} + +static inline void write_tag_block(int tag_bytes, journal_block_tag_t *tag, + unsigned long long block) +{ + tag->t_blocknr = cpu_to_be32(block & (u32)~0); + if (tag_bytes > JBD_TAG_SIZE32) + tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1); +} + +/* + * jbd2_journal_commit_transaction + * + * The primary function for committing a transaction to the log. This + * function is called by the journal thread to begin a complete commit. + */ +void jbd2_journal_commit_transaction(journal_t *journal) +{ + transaction_t *commit_transaction; + struct journal_head *jh, *new_jh, *descriptor; + struct buffer_head **wbuf = journal->j_wbuf; + int bufs; + int flags; + int err; + unsigned long long blocknr; + char *tagp = NULL; + journal_header_t *header; + journal_block_tag_t *tag = NULL; + int space_left = 0; + int first_tag = 0; + int tag_flag; + int i; + int tag_bytes = journal_tag_bytes(journal); + + /* + * First job: lock down the current transaction and wait for + * all outstanding updates to complete. + */ + +#ifdef COMMIT_STATS + spin_lock(&journal->j_list_lock); + summarise_journal_usage(journal); + spin_unlock(&journal->j_list_lock); +#endif + + /* Do we need to erase the effects of a prior jbd2_journal_flush? */ + if (journal->j_flags & JBD2_FLUSHED) { + jbd_debug(3, "super block updated\n"); + jbd2_journal_update_superblock(journal, 1); + } else { + jbd_debug(3, "superblock not updated\n"); + } + + J_ASSERT(journal->j_running_transaction != NULL); + J_ASSERT(journal->j_committing_transaction == NULL); + + commit_transaction = journal->j_running_transaction; + J_ASSERT(commit_transaction->t_state == T_RUNNING); + + jbd_debug(1, "JBD: starting commit of transaction %d\n", + commit_transaction->t_tid); + + spin_lock(&journal->j_state_lock); + commit_transaction->t_state = T_LOCKED; + + spin_lock(&commit_transaction->t_handle_lock); + while (commit_transaction->t_updates) { + DEFINE_WAIT(wait); + + prepare_to_wait(&journal->j_wait_updates, &wait, + TASK_UNINTERRUPTIBLE); + if (commit_transaction->t_updates) { + spin_unlock(&commit_transaction->t_handle_lock); + spin_unlock(&journal->j_state_lock); + schedule(); + spin_lock(&journal->j_state_lock); + spin_lock(&commit_transaction->t_handle_lock); + } + finish_wait(&journal->j_wait_updates, &wait); + } + spin_unlock(&commit_transaction->t_handle_lock); + + J_ASSERT (commit_transaction->t_outstanding_credits <= + journal->j_max_transaction_buffers); + + /* + * First thing we are allowed to do is to discard any remaining + * BJ_Reserved buffers. Note, it is _not_ permissible to assume + * that there are no such buffers: if a large filesystem + * operation like a truncate needs to split itself over multiple + * transactions, then it may try to do a jbd2_journal_restart() while + * there are still BJ_Reserved buffers outstanding. These must + * be released cleanly from the current transaction. + * + * In this case, the filesystem must still reserve write access + * again before modifying the buffer in the new transaction, but + * we do not require it to remember exactly which old buffers it + * has reserved. This is consistent with the existing behaviour + * that multiple jbd2_journal_get_write_access() calls to the same + * buffer are perfectly permissable. + */ + while (commit_transaction->t_reserved_list) { + jh = commit_transaction->t_reserved_list; + JBUFFER_TRACE(jh, "reserved, unused: refile"); + /* + * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may + * leave undo-committed data. + */ + if (jh->b_committed_data) { + struct buffer_head *bh = jh2bh(jh); + + jbd_lock_bh_state(bh); + jbd2_slab_free(jh->b_committed_data, bh->b_size); + jh->b_committed_data = NULL; + jbd_unlock_bh_state(bh); + } + jbd2_journal_refile_buffer(journal, jh); + } + + /* + * Now try to drop any written-back buffers from the journal's + * checkpoint lists. We do this *before* commit because it potentially + * frees some memory + */ + spin_lock(&journal->j_list_lock); + __jbd2_journal_clean_checkpoint_list(journal); + spin_unlock(&journal->j_list_lock); + + jbd_debug (3, "JBD: commit phase 1\n"); + + /* + * Switch to a new revoke table. + */ + jbd2_journal_switch_revoke_table(journal); + + commit_transaction->t_state = T_FLUSH; + journal->j_committing_transaction = commit_transaction; + journal->j_running_transaction = NULL; + commit_transaction->t_log_start = journal->j_head; + wake_up(&journal->j_wait_transaction_locked); + spin_unlock(&journal->j_state_lock); + + jbd_debug (3, "JBD: commit phase 2\n"); + + /* + * First, drop modified flag: all accesses to the buffers + * will be tracked for a new trasaction only -bzzz + */ + spin_lock(&journal->j_list_lock); + if (commit_transaction->t_buffers) { + new_jh = jh = commit_transaction->t_buffers->b_tnext; + do { + J_ASSERT_JH(new_jh, new_jh->b_modified == 1 || + new_jh->b_modified == 0); + new_jh->b_modified = 0; + new_jh = new_jh->b_tnext; + } while (new_jh != jh); + } + spin_unlock(&journal->j_list_lock); + + /* + * Now start flushing things to disk, in the order they appear + * on the transaction lists. Data blocks go first. + */ + err = 0; + journal_submit_data_buffers(journal, commit_transaction); + + /* + * Wait for all previously submitted IO to complete. + */ + spin_lock(&journal->j_list_lock); + while (commit_transaction->t_locked_list) { + struct buffer_head *bh; + + jh = commit_transaction->t_locked_list->b_tprev; + bh = jh2bh(jh); + get_bh(bh); + if (buffer_locked(bh)) { + spin_unlock(&journal->j_list_lock); + wait_on_buffer(bh); + if (unlikely(!buffer_uptodate(bh))) + err = -EIO; + spin_lock(&journal->j_list_lock); + } + if (!inverted_lock(journal, bh)) { + put_bh(bh); + spin_lock(&journal->j_list_lock); + continue; + } + if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) { + __jbd2_journal_unfile_buffer(jh); + jbd_unlock_bh_state(bh); + jbd2_journal_remove_journal_head(bh); + put_bh(bh); + } else { + jbd_unlock_bh_state(bh); + } + put_bh(bh); + cond_resched_lock(&journal->j_list_lock); + } + spin_unlock(&journal->j_list_lock); + + if (err) + __jbd2_journal_abort_hard(journal); + + jbd2_journal_write_revoke_records(journal, commit_transaction); + + jbd_debug(3, "JBD: commit phase 2\n"); + + /* + * If we found any dirty or locked buffers, then we should have + * looped back up to the write_out_data label. If there weren't + * any then journal_clean_data_list should have wiped the list + * clean by now, so check that it is in fact empty. + */ + J_ASSERT (commit_transaction->t_sync_datalist == NULL); + + jbd_debug (3, "JBD: commit phase 3\n"); + + /* + * Way to go: we have now written out all of the data for a + * transaction! Now comes the tricky part: we need to write out + * metadata. Loop over the transaction's entire buffer list: + */ + commit_transaction->t_state = T_COMMIT; + + descriptor = NULL; + bufs = 0; + while (commit_transaction->t_buffers) { + + /* Find the next buffer to be journaled... */ + + jh = commit_transaction->t_buffers; + + /* If we're in abort mode, we just un-journal the buffer and + release it for background writing. */ + + if (is_journal_aborted(journal)) { + JBUFFER_TRACE(jh, "journal is aborting: refile"); + jbd2_journal_refile_buffer(journal, jh); + /* If that was the last one, we need to clean up + * any descriptor buffers which may have been + * already allocated, even if we are now + * aborting. */ + if (!commit_transaction->t_buffers) + goto start_journal_io; + continue; + } + + /* Make sure we have a descriptor block in which to + record the metadata buffer. */ + + if (!descriptor) { + struct buffer_head *bh; + + J_ASSERT (bufs == 0); + + jbd_debug(4, "JBD: get descriptor\n"); + + descriptor = jbd2_journal_get_descriptor_buffer(journal); + if (!descriptor) { + __jbd2_journal_abort_hard(journal); + continue; + } + + bh = jh2bh(descriptor); + jbd_debug(4, "JBD: got buffer %llu (%p)\n", + (unsigned long long)bh->b_blocknr, bh->b_data); + header = (journal_header_t *)&bh->b_data[0]; + header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); + header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK); + header->h_sequence = cpu_to_be32(commit_transaction->t_tid); + + tagp = &bh->b_data[sizeof(journal_header_t)]; + space_left = bh->b_size - sizeof(journal_header_t); + first_tag = 1; + set_buffer_jwrite(bh); + set_buffer_dirty(bh); + wbuf[bufs++] = bh; + + /* Record it so that we can wait for IO + completion later */ + BUFFER_TRACE(bh, "ph3: file as descriptor"); + jbd2_journal_file_buffer(descriptor, commit_transaction, + BJ_LogCtl); + } + + /* Where is the buffer to be written? */ + + err = jbd2_journal_next_log_block(journal, &blocknr); + /* If the block mapping failed, just abandon the buffer + and repeat this loop: we'll fall into the + refile-on-abort condition above. */ + if (err) { + __jbd2_journal_abort_hard(journal); + continue; + } + + /* + * start_this_handle() uses t_outstanding_credits to determine + * the free space in the log, but this counter is changed + * by jbd2_journal_next_log_block() also. + */ + commit_transaction->t_outstanding_credits--; + + /* Bump b_count to prevent truncate from stumbling over + the shadowed buffer! @@@ This can go if we ever get + rid of the BJ_IO/BJ_Shadow pairing of buffers. */ + atomic_inc(&jh2bh(jh)->b_count); + + /* Make a temporary IO buffer with which to write it out + (this will requeue both the metadata buffer and the + temporary IO buffer). new_bh goes on BJ_IO*/ + + set_bit(BH_JWrite, &jh2bh(jh)->b_state); + /* + * akpm: jbd2_journal_write_metadata_buffer() sets + * new_bh->b_transaction to commit_transaction. + * We need to clean this up before we release new_bh + * (which is of type BJ_IO) + */ + JBUFFER_TRACE(jh, "ph3: write metadata"); + flags = jbd2_journal_write_metadata_buffer(commit_transaction, + jh, &new_jh, blocknr); + set_bit(BH_JWrite, &jh2bh(new_jh)->b_state); + wbuf[bufs++] = jh2bh(new_jh); + + /* Record the new block's tag in the current descriptor + buffer */ + + tag_flag = 0; + if (flags & 1) + tag_flag |= JBD2_FLAG_ESCAPE; + if (!first_tag) + tag_flag |= JBD2_FLAG_SAME_UUID; + + tag = (journal_block_tag_t *) tagp; + write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr); + tag->t_flags = cpu_to_be32(tag_flag); + tagp += tag_bytes; + space_left -= tag_bytes; + + if (first_tag) { + memcpy (tagp, journal->j_uuid, 16); + tagp += 16; + space_left -= 16; + first_tag = 0; + } + + /* If there's no more to do, or if the descriptor is full, + let the IO rip! */ + + if (bufs == journal->j_wbufsize || + commit_transaction->t_buffers == NULL || + space_left < tag_bytes + 16) { + + jbd_debug(4, "JBD: Submit %d IOs\n", bufs); + + /* Write an end-of-descriptor marker before + submitting the IOs. "tag" still points to + the last tag we set up. */ + + tag->t_flags |= cpu_to_be32(JBD2_FLAG_LAST_TAG); + +start_journal_io: + for (i = 0; i < bufs; i++) { + struct buffer_head *bh = wbuf[i]; + lock_buffer(bh); + clear_buffer_dirty(bh); + set_buffer_uptodate(bh); + bh->b_end_io = journal_end_buffer_io_sync; + submit_bh(WRITE, bh); + } + cond_resched(); + + /* Force a new descriptor to be generated next + time round the loop. */ + descriptor = NULL; + bufs = 0; + } + } + + /* Lo and behold: we have just managed to send a transaction to + the log. Before we can commit it, wait for the IO so far to + complete. Control buffers being written are on the + transaction's t_log_list queue, and metadata buffers are on + the t_iobuf_list queue. + + Wait for the buffers in reverse order. That way we are + less likely to be woken up until all IOs have completed, and + so we incur less scheduling load. + */ + + jbd_debug(3, "JBD: commit phase 4\n"); + + /* + * akpm: these are BJ_IO, and j_list_lock is not needed. + * See __journal_try_to_free_buffer. + */ +wait_for_iobuf: + while (commit_transaction->t_iobuf_list != NULL) { + struct buffer_head *bh; + + jh = commit_transaction->t_iobuf_list->b_tprev; + bh = jh2bh(jh); + if (buffer_locked(bh)) { + wait_on_buffer(bh); + goto wait_for_iobuf; + } + if (cond_resched()) + goto wait_for_iobuf; + + if (unlikely(!buffer_uptodate(bh))) + err = -EIO; + + clear_buffer_jwrite(bh); + + JBUFFER_TRACE(jh, "ph4: unfile after journal write"); + jbd2_journal_unfile_buffer(journal, jh); + + /* + * ->t_iobuf_list should contain only dummy buffer_heads + * which were created by jbd2_journal_write_metadata_buffer(). + */ + BUFFER_TRACE(bh, "dumping temporary bh"); + jbd2_journal_put_journal_head(jh); + __brelse(bh); + J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0); + free_buffer_head(bh); + + /* We also have to unlock and free the corresponding + shadowed buffer */ + jh = commit_transaction->t_shadow_list->b_tprev; + bh = jh2bh(jh); + clear_bit(BH_JWrite, &bh->b_state); + J_ASSERT_BH(bh, buffer_jbddirty(bh)); + + /* The metadata is now released for reuse, but we need + to remember it against this transaction so that when + we finally commit, we can do any checkpointing + required. */ + JBUFFER_TRACE(jh, "file as BJ_Forget"); + jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget); + /* Wake up any transactions which were waiting for this + IO to complete */ + wake_up_bit(&bh->b_state, BH_Unshadow); + JBUFFER_TRACE(jh, "brelse shadowed buffer"); + __brelse(bh); + } + + J_ASSERT (commit_transaction->t_shadow_list == NULL); + + jbd_debug(3, "JBD: commit phase 5\n"); + + /* Here we wait for the revoke record and descriptor record buffers */ + wait_for_ctlbuf: + while (commit_transaction->t_log_list != NULL) { + struct buffer_head *bh; + + jh = commit_transaction->t_log_list->b_tprev; + bh = jh2bh(jh); + if (buffer_locked(bh)) { + wait_on_buffer(bh); + goto wait_for_ctlbuf; + } + if (cond_resched()) + goto wait_for_ctlbuf; + + if (unlikely(!buffer_uptodate(bh))) + err = -EIO; + + BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile"); + clear_buffer_jwrite(bh); + jbd2_journal_unfile_buffer(journal, jh); + jbd2_journal_put_journal_head(jh); + __brelse(bh); /* One for getblk */ + /* AKPM: bforget here */ + } + + jbd_debug(3, "JBD: commit phase 6\n"); + + if (journal_write_commit_record(journal, commit_transaction)) + err = -EIO; + + if (err) + __jbd2_journal_abort_hard(journal); + + /* End of a transaction! Finally, we can do checkpoint + processing: any buffers committed as a result of this + transaction can be removed from any checkpoint list it was on + before. */ + + jbd_debug(3, "JBD: commit phase 7\n"); + + J_ASSERT(commit_transaction->t_sync_datalist == NULL); + J_ASSERT(commit_transaction->t_buffers == NULL); + J_ASSERT(commit_transaction->t_checkpoint_list == NULL); + J_ASSERT(commit_transaction->t_iobuf_list == NULL); + J_ASSERT(commit_transaction->t_shadow_list == NULL); + J_ASSERT(commit_transaction->t_log_list == NULL); + +restart_loop: + /* + * As there are other places (journal_unmap_buffer()) adding buffers + * to this list we have to be careful and hold the j_list_lock. + */ + spin_lock(&journal->j_list_lock); + while (commit_transaction->t_forget) { + transaction_t *cp_transaction; + struct buffer_head *bh; + + jh = commit_transaction->t_forget; + spin_unlock(&journal->j_list_lock); + bh = jh2bh(jh); + jbd_lock_bh_state(bh); + J_ASSERT_JH(jh, jh->b_transaction == commit_transaction || + jh->b_transaction == journal->j_running_transaction); + + /* + * If there is undo-protected committed data against + * this buffer, then we can remove it now. If it is a + * buffer needing such protection, the old frozen_data + * field now points to a committed version of the + * buffer, so rotate that field to the new committed + * data. + * + * Otherwise, we can just throw away the frozen data now. + */ + if (jh->b_committed_data) { + jbd2_slab_free(jh->b_committed_data, bh->b_size); + jh->b_committed_data = NULL; + if (jh->b_frozen_data) { + jh->b_committed_data = jh->b_frozen_data; + jh->b_frozen_data = NULL; + } + } else if (jh->b_frozen_data) { + jbd2_slab_free(jh->b_frozen_data, bh->b_size); + jh->b_frozen_data = NULL; + } + + spin_lock(&journal->j_list_lock); + cp_transaction = jh->b_cp_transaction; + if (cp_transaction) { + JBUFFER_TRACE(jh, "remove from old cp transaction"); + __jbd2_journal_remove_checkpoint(jh); + } + + /* Only re-checkpoint the buffer_head if it is marked + * dirty. If the buffer was added to the BJ_Forget list + * by jbd2_journal_forget, it may no longer be dirty and + * there's no point in keeping a checkpoint record for + * it. */ + + /* A buffer which has been freed while still being + * journaled by a previous transaction may end up still + * being dirty here, but we want to avoid writing back + * that buffer in the future now that the last use has + * been committed. That's not only a performance gain, + * it also stops aliasing problems if the buffer is left + * behind for writeback and gets reallocated for another + * use in a different page. */ + if (buffer_freed(bh)) { + clear_buffer_freed(bh); + clear_buffer_jbddirty(bh); + } + + if (buffer_jbddirty(bh)) { + JBUFFER_TRACE(jh, "add to new checkpointing trans"); + __jbd2_journal_insert_checkpoint(jh, commit_transaction); + JBUFFER_TRACE(jh, "refile for checkpoint writeback"); + __jbd2_journal_refile_buffer(jh); + jbd_unlock_bh_state(bh); + } else { + J_ASSERT_BH(bh, !buffer_dirty(bh)); + /* The buffer on BJ_Forget list and not jbddirty means + * it has been freed by this transaction and hence it + * could not have been reallocated until this + * transaction has committed. *BUT* it could be + * reallocated once we have written all the data to + * disk and before we process the buffer on BJ_Forget + * list. */ + JBUFFER_TRACE(jh, "refile or unfile freed buffer"); + __jbd2_journal_refile_buffer(jh); + if (!jh->b_transaction) { + jbd_unlock_bh_state(bh); + /* needs a brelse */ + jbd2_journal_remove_journal_head(bh); + release_buffer_page(bh); + } else + jbd_unlock_bh_state(bh); + } + cond_resched_lock(&journal->j_list_lock); + } + spin_unlock(&journal->j_list_lock); + /* + * This is a bit sleazy. We borrow j_list_lock to protect + * journal->j_committing_transaction in __jbd2_journal_remove_checkpoint. + * Really, __jbd2_journal_remove_checkpoint should be using j_state_lock but + * it's a bit hassle to hold that across __jbd2_journal_remove_checkpoint + */ + spin_lock(&journal->j_state_lock); + spin_lock(&journal->j_list_lock); + /* + * Now recheck if some buffers did not get attached to the transaction + * while the lock was dropped... + */ + if (commit_transaction->t_forget) { + spin_unlock(&journal->j_list_lock); + spin_unlock(&journal->j_state_lock); + goto restart_loop; + } + + /* Done with this transaction! */ + + jbd_debug(3, "JBD: commit phase 8\n"); + + J_ASSERT(commit_transaction->t_state == T_COMMIT); + + commit_transaction->t_state = T_FINISHED; + J_ASSERT(commit_transaction == journal->j_committing_transaction); + journal->j_commit_sequence = commit_transaction->t_tid; + journal->j_committing_transaction = NULL; + spin_unlock(&journal->j_state_lock); + + if (commit_transaction->t_checkpoint_list == NULL) { + __jbd2_journal_drop_transaction(journal, commit_transaction); + } else { + if (journal->j_checkpoint_transactions == NULL) { + journal->j_checkpoint_transactions = commit_transaction; + commit_transaction->t_cpnext = commit_transaction; + commit_transaction->t_cpprev = commit_transaction; + } else { + commit_transaction->t_cpnext = + journal->j_checkpoint_transactions; + commit_transaction->t_cpprev = + commit_transaction->t_cpnext->t_cpprev; + commit_transaction->t_cpnext->t_cpprev = + commit_transaction; + commit_transaction->t_cpprev->t_cpnext = + commit_transaction; + } + } + spin_unlock(&journal->j_list_lock); + + jbd_debug(1, "JBD: commit %d complete, head %d\n", + journal->j_commit_sequence, journal->j_tail_sequence); + + wake_up(&journal->j_wait_done_commit); +} |