--- /dev/null
+/*
+ * linux/fs/jbd/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/jbd.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <trace/events/jbd.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 successfully 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 journal->j_list_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 (!trylock_page(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);
+}
+
+/*
+ * Decrement reference counter for data buffer. If it has been marked
+ * 'BH_Freed', release it and the page to which it belongs if possible.
+ */
+static void release_data_buffer(struct buffer_head *bh)
+{
+ if (buffer_freed(bh)) {
+ WARN_ON_ONCE(buffer_dirty(bh));
+ clear_buffer_freed(bh);
+ clear_buffer_mapped(bh);
+ clear_buffer_new(bh);
+ clear_buffer_req(bh);
+ bh->b_bdev = NULL;
+ release_buffer_page(bh);
+ } else
+ put_bh(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;
+ journal_header_t *header;
+ int ret;
+
+ if (is_journal_aborted(journal))
+ return 0;
+
+ descriptor = journal_get_descriptor_buffer(journal);
+ if (!descriptor)
+ return 1;
+
+ bh = jh2bh(descriptor);
+
+ header = (journal_header_t *)(bh->b_data);
+ header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
+ header->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK);
+ header->h_sequence = cpu_to_be32(commit_transaction->t_tid);
+
+ JBUFFER_TRACE(descriptor, "write commit block");
+ set_buffer_dirty(bh);
+
+ if (journal->j_flags & JFS_BARRIER)
+ ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_FLUSH_FUA);
+ else
+ ret = sync_dirty_buffer(bh);
+
+ put_bh(bh); /* One for getblk() */
+ journal_put_journal_head(descriptor);
+
+ return (ret == -EIO);
+}
+
+static void journal_do_submit_data(struct buffer_head **wbuf, int bufs,
+ int write_op)
+{
+ int i;
+
+ for (i = 0; i < bufs; i++) {
+ wbuf[i]->b_end_io = end_buffer_write_sync;
+ /*
+ * Here we write back pagecache data that may be mmaped. Since
+ * we cannot afford to clean the page and set PageWriteback
+ * here due to lock ordering (page lock ranks above transaction
+ * start), the data can change while IO is in flight. Tell the
+ * block layer it should bounce the bio pages if stable data
+ * during write is required.
+ *
+ * We use up our safety reference in submit_bh().
+ */
+ _submit_bh(write_op, wbuf[i], 1 << BIO_SNAP_STABLE);
+ }
+}
+
+/*
+ * Submit all the data buffers to disk
+ */
+static int journal_submit_data_buffers(journal_t *journal,
+ transaction_t *commit_transaction,
+ int write_op)
+{
+ struct journal_head *jh;
+ struct buffer_head *bh;
+ int locked;
+ int bufs = 0;
+ struct buffer_head **wbuf = journal->j_wbuf;
+ int err = 0;
+
+ /*
+ * 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 (!trylock_buffer(bh)) {
+ BUFFER_TRACE(bh, "needs blocking lock");
+ spin_unlock(&journal->j_list_lock);
+ trace_jbd_do_submit_data(journal,
+ commit_transaction);
+ /* Write out all data to prevent deadlocks */
+ journal_do_submit_data(wbuf, bufs, write_op);
+ 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) || bh2jh(bh) != jh
+ || 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");
+ release_data_buffer(bh);
+ continue;
+ }
+ if (locked && test_clear_buffer_dirty(bh)) {
+ BUFFER_TRACE(bh, "needs writeout, adding to array");
+ wbuf[bufs++] = bh;
+ __journal_file_buffer(jh, commit_transaction,
+ BJ_Locked);
+ jbd_unlock_bh_state(bh);
+ if (bufs == journal->j_wbufsize) {
+ spin_unlock(&journal->j_list_lock);
+ trace_jbd_do_submit_data(journal,
+ commit_transaction);
+ journal_do_submit_data(wbuf, bufs, write_op);
+ bufs = 0;
+ goto write_out_data;
+ }
+ } else if (!locked && buffer_locked(bh)) {
+ __journal_file_buffer(jh, commit_transaction,
+ BJ_Locked);
+ jbd_unlock_bh_state(bh);
+ put_bh(bh);
+ } else {
+ BUFFER_TRACE(bh, "writeout complete: unfile");
+ if (unlikely(!buffer_uptodate(bh)))
+ err = -EIO;
+ __journal_unfile_buffer(jh);
+ jbd_unlock_bh_state(bh);
+ if (locked)
+ unlock_buffer(bh);
+ release_data_buffer(bh);
+ }
+
+ if (need_resched() || spin_needbreak(&journal->j_list_lock)) {
+ spin_unlock(&journal->j_list_lock);
+ goto write_out_data;
+ }
+ }
+ spin_unlock(&journal->j_list_lock);
+ trace_jbd_do_submit_data(journal, commit_transaction);
+ journal_do_submit_data(wbuf, bufs, write_op);
+
+ return err;
+}
+
+/*
+ * 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 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 int blocknr;
+ ktime_t start_time;
+ u64 commit_time;
+ 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;
+ struct blk_plug plug;
+ int write_op = WRITE;
+
+ /*
+ * First job: lock down the current transaction and wait for
+ * all outstanding updates to complete.
+ */
+
+ /* Do we need to erase the effects of a prior journal_flush? */
+ if (journal->j_flags & JFS_FLUSHED) {
+ jbd_debug(3, "super block updated\n");
+ mutex_lock(&journal->j_checkpoint_mutex);
+ /*
+ * We hold j_checkpoint_mutex so tail cannot change under us.
+ * We don't need any special data guarantees for writing sb
+ * since journal is empty and it is ok for write to be
+ * flushed only with transaction commit.
+ */
+ journal_update_sb_log_tail(journal, journal->j_tail_sequence,
+ journal->j_tail, WRITE_SYNC);
+ mutex_unlock(&journal->j_checkpoint_mutex);
+ } 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;
+
+ trace_jbd_start_commit(journal, commit_transaction);
+ jbd_debug(1, "JBD: starting commit of transaction %d\n",
+ commit_transaction->t_tid);
+
+ spin_lock(&journal->j_state_lock);
+ J_ASSERT(commit_transaction->t_state == T_RUNNING);
+ commit_transaction->t_state = T_LOCKED;
+
+ trace_jbd_commit_locking(journal, commit_transaction);
+ 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 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 journal_get_write_access() calls to the same
+ * buffer are perfectly permissible.
+ */
+ while (commit_transaction->t_reserved_list) {
+ jh = commit_transaction->t_reserved_list;
+ JBUFFER_TRACE(jh, "reserved, unused: refile");
+ /*
+ * A journal_get_undo_access()+journal_release_buffer() may
+ * leave undo-committed data.
+ */
+ if (jh->b_committed_data) {
+ struct buffer_head *bh = jh2bh(jh);
+
+ jbd_lock_bh_state(bh);
+ jbd_free(jh->b_committed_data, bh->b_size);
+ jh->b_committed_data = NULL;
+ jbd_unlock_bh_state(bh);
+ }
+ 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);
+ __journal_clean_checkpoint_list(journal);
+ spin_unlock(&journal->j_list_lock);
+
+ jbd_debug (3, "JBD: commit phase 1\n");
+
+ /*
+ * Clear revoked flag to reflect there is no revoked buffers
+ * in the next transaction which is going to be started.
+ */
+ journal_clear_buffer_revoked_flags(journal);
+
+ /*
+ * Switch to a new revoke table.
+ */
+ journal_switch_revoke_table(journal);
+
+ trace_jbd_commit_flushing(journal, commit_transaction);
+ commit_transaction->t_state = T_FLUSH;
+ journal->j_committing_transaction = commit_transaction;
+ journal->j_running_transaction = NULL;
+ start_time = ktime_get();
+ 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");
+
+ if (tid_geq(journal->j_commit_waited, commit_transaction->t_tid))
+ write_op = WRITE_SYNC;
+
+ /*
+ * Now start flushing things to disk, in the order they appear
+ * on the transaction lists. Data blocks go first.
+ */
+ blk_start_plug(&plug);
+ err = journal_submit_data_buffers(journal, commit_transaction,
+ write_op);
+ blk_finish_plug(&plug);
+
+ /*
+ * 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);
+ spin_lock(&journal->j_list_lock);
+ }
+ if (unlikely(!buffer_uptodate(bh))) {
+ if (!trylock_page(bh->b_page)) {
+ spin_unlock(&journal->j_list_lock);
+ lock_page(bh->b_page);
+ spin_lock(&journal->j_list_lock);
+ }
+ if (bh->b_page->mapping)
+ set_bit(AS_EIO, &bh->b_page->mapping->flags);
+
+ unlock_page(bh->b_page);
+ SetPageError(bh->b_page);
+ err = -EIO;
+ }
+ if (!inverted_lock(journal, bh)) {
+ put_bh(bh);
+ spin_lock(&journal->j_list_lock);
+ continue;
+ }
+ if (buffer_jbd(bh) && bh2jh(bh) == jh &&
+ jh->b_transaction == commit_transaction &&
+ jh->b_jlist == BJ_Locked)
+ __journal_unfile_buffer(jh);
+ jbd_unlock_bh_state(bh);
+ release_data_buffer(bh);
+ cond_resched_lock(&journal->j_list_lock);
+ }
+ spin_unlock(&journal->j_list_lock);
+
+ if (err) {
+ char b[BDEVNAME_SIZE];
+
+ printk(KERN_WARNING
+ "JBD: Detected IO errors while flushing file data "
+ "on %s\n", bdevname(journal->j_fs_dev, b));
+ if (journal->j_flags & JFS_ABORT_ON_SYNCDATA_ERR)
+ journal_abort(journal, err);
+ err = 0;
+ }
+
+ blk_start_plug(&plug);
+
+ journal_write_revoke_records(journal, commit_transaction, write_op);
+
+ /*
+ * 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:
+ */
+ spin_lock(&journal->j_state_lock);
+ commit_transaction->t_state = T_COMMIT;
+ spin_unlock(&journal->j_state_lock);
+
+ trace_jbd_commit_logging(journal, commit_transaction);
+ J_ASSERT(commit_transaction->t_nr_buffers <=
+ commit_transaction->t_outstanding_credits);
+
+ 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. */
+
+ if (is_journal_aborted(journal)) {
+ clear_buffer_jbddirty(jh2bh(jh));
+ JBUFFER_TRACE(jh, "journal is aborting: refile");
+ 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 = journal_get_descriptor_buffer(journal);
+ if (!descriptor) {
+ journal_abort(journal, -EIO);
+ 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(JFS_MAGIC_NUMBER);
+ header->h_blocktype = cpu_to_be32(JFS_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");
+ journal_file_buffer(descriptor, commit_transaction,
+ BJ_LogCtl);
+ }
+
+ /* Where is the buffer to be written? */
+
+ err = 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) {
+ journal_abort(journal, err);
+ continue;
+ }
+
+ /*
+ * start_this_handle() uses t_outstanding_credits to determine
+ * the free space in the log, but this counter is changed
+ * by 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. */
+ get_bh(jh2bh(jh));
+
+ /* 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_buffer_jwrite(jh2bh(jh));
+ /*
+ * akpm: 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 = journal_write_metadata_buffer(commit_transaction,
+ jh, &new_jh, blocknr);
+ set_buffer_jwrite(jh2bh(new_jh));
+ wbuf[bufs++] = jh2bh(new_jh);
+
+ /* Record the new block's tag in the current descriptor
+ buffer */
+
+ tag_flag = 0;
+ if (flags & 1)
+ tag_flag |= JFS_FLAG_ESCAPE;
+ if (!first_tag)
+ tag_flag |= JFS_FLAG_SAME_UUID;
+
+ tag = (journal_block_tag_t *) tagp;
+ tag->t_blocknr = cpu_to_be32(jh2bh(jh)->b_blocknr);
+ tag->t_flags = cpu_to_be32(tag_flag);
+ tagp += sizeof(journal_block_tag_t);
+ space_left -= sizeof(journal_block_tag_t);
+
+ 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 < sizeof(journal_block_tag_t) + 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(JFS_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;
+ /*
+ * In data=journal mode, here we can end up
+ * writing pagecache data that might be
+ * mmapped. Since we can't afford to clean the
+ * page and set PageWriteback (see the comment
+ * near the other use of _submit_bh()), the
+ * data can change while the write is in
+ * flight. Tell the block layer to bounce the
+ * bio pages if stable pages are required.
+ */
+ _submit_bh(write_op, bh, 1 << BIO_SNAP_STABLE);
+ }
+ cond_resched();
+
+ /* Force a new descriptor to be generated next
+ time round the loop. */
+ descriptor = NULL;
+ bufs = 0;
+ }
+ }
+
+ blk_finish_plug(&plug);
+
+ /* 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");
+ journal_unfile_buffer(journal, jh);
+
+ /*
+ * ->t_iobuf_list should contain only dummy buffer_heads
+ * which were created by journal_write_metadata_buffer().
+ */
+ BUFFER_TRACE(bh, "dumping temporary bh");
+ 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_buffer_jwrite(bh);
+ 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");
+ journal_file_buffer(jh, commit_transaction, BJ_Forget);
+ /*
+ * Wake up any transactions which were waiting for this
+ * IO to complete. The barrier must be here so that changes
+ * by journal_file_buffer() take effect before wake_up_bit()
+ * does the waitqueue check.
+ */
+ smp_mb();
+ 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);
+ journal_unfile_buffer(journal, jh);
+ journal_put_journal_head(jh);
+ __brelse(bh); /* One for getblk */
+ /* AKPM: bforget here */
+ }
+
+ if (err)
+ journal_abort(journal, err);
+
+ jbd_debug(3, "JBD: commit phase 6\n");
+
+ /* All metadata is written, now write commit record and do cleanup */
+ spin_lock(&journal->j_state_lock);
+ J_ASSERT(commit_transaction->t_state == T_COMMIT);
+ commit_transaction->t_state = T_COMMIT_RECORD;
+ spin_unlock(&journal->j_state_lock);
+
+ if (journal_write_commit_record(journal, commit_transaction))
+ err = -EIO;
+
+ if (err)
+ journal_abort(journal, err);
+
+ /* 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;
+ int try_to_free = 0;
+
+ jh = commit_transaction->t_forget;
+ spin_unlock(&journal->j_list_lock);
+ bh = jh2bh(jh);
+ /*
+ * Get a reference so that bh cannot be freed before we are
+ * done with it.
+ */
+ get_bh(bh);
+ 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) {
+ jbd_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) {
+ jbd_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");
+ __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 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.
+ */
+ if (buffer_freed(bh)) {
+ /*
+ * If the running transaction is the one containing
+ * "add to orphan" operation (b_next_transaction !=
+ * NULL), we have to wait for that transaction to
+ * commit before we can really get rid of the buffer.
+ * So just clear b_modified to not confuse transaction
+ * credit accounting and refile the buffer to
+ * BJ_Forget of the running transaction. If the just
+ * committed transaction contains "add to orphan"
+ * operation, we can completely invalidate the buffer
+ * now. We are rather throughout in that since the
+ * buffer may be still accessible when blocksize <
+ * pagesize and it is attached to the last partial
+ * page.
+ */
+ jh->b_modified = 0;
+ if (!jh->b_next_transaction) {
+ clear_buffer_freed(bh);
+ clear_buffer_jbddirty(bh);
+ clear_buffer_mapped(bh);
+ clear_buffer_new(bh);
+ clear_buffer_req(bh);
+ bh->b_bdev = NULL;
+ }
+ }
+
+ if (buffer_jbddirty(bh)) {
+ JBUFFER_TRACE(jh, "add to new checkpointing trans");
+ __journal_insert_checkpoint(jh, commit_transaction);
+ if (is_journal_aborted(journal))
+ clear_buffer_jbddirty(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.
+ */
+ if (!jh->b_next_transaction)
+ try_to_free = 1;
+ }
+ JBUFFER_TRACE(jh, "refile or unfile freed buffer");
+ __journal_refile_buffer(jh);
+ jbd_unlock_bh_state(bh);
+ if (try_to_free)
+ release_buffer_page(bh);
+ else
+ __brelse(bh);
+ cond_resched_lock(&journal->j_list_lock);
+ }
+ spin_unlock(&journal->j_list_lock);
+ /*
+ * This is a bit sleazy. We use j_list_lock to protect transition
+ * of a transaction into T_FINISHED state and calling
+ * __journal_drop_transaction(). Otherwise we could race with
+ * other checkpointing code processing the transaction...
+ */
+ 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_RECORD);
+
+ 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;
+ commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
+
+ /*
+ * weight the commit time higher than the average time so we don't
+ * react too strongly to vast changes in commit time
+ */
+ if (likely(journal->j_average_commit_time))
+ journal->j_average_commit_time = (commit_time*3 +
+ journal->j_average_commit_time) / 4;
+ else
+ journal->j_average_commit_time = commit_time;
+
+ spin_unlock(&journal->j_state_lock);
+
+ if (commit_transaction->t_checkpoint_list == NULL &&
+ commit_transaction->t_checkpoint_io_list == NULL) {
+ __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);
+
+ trace_jbd_end_commit(journal, commit_transaction);
+ 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);
+}
Code Review / kvmfornfv.git / blobdiff