jbd2: split updating of journal superblock and marking journal empty
There are three case of updating journal superblock. In the first case, we want to mark journal as empty (setting s_sequence to 0), in the second case we want to update log tail, in the third case we want to update s_errno. Split these cases into separate functions. It makes the code slightly more straightforward and later patches will make the distinction even more important. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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@ -550,7 +550,7 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
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(journal->j_flags & JBD2_BARRIER))
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blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
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if (!(journal->j_flags & JBD2_ABORT))
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jbd2_journal_update_superblock(journal, 1);
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jbd2_journal_update_sb_log_tail(journal);
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return 0;
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}
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@ -340,7 +340,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
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/* Do we need to erase the effects of a prior jbd2_journal_flush? */
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if (journal->j_flags & JBD2_FLUSHED) {
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jbd_debug(3, "super block updated\n");
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jbd2_journal_update_superblock(journal, 1);
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jbd2_journal_update_sb_log_tail(journal);
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} else {
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jbd_debug(3, "superblock not updated\n");
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}
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@ -1110,40 +1110,30 @@ static int journal_reset(journal_t *journal)
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journal->j_max_transaction_buffers = journal->j_maxlen / 4;
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/* Add the dynamic fields and write it to disk. */
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jbd2_journal_update_superblock(journal, 1);
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return jbd2_journal_start_thread(journal);
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}
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/**
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* void jbd2_journal_update_superblock() - Update journal sb on disk.
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* @journal: The journal to update.
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* @wait: Set to '0' if you don't want to wait for IO completion.
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*
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* Update a journal's dynamic superblock fields and write it to disk,
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* optionally waiting for the IO to complete.
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*/
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void jbd2_journal_update_superblock(journal_t *journal, int wait)
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{
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journal_superblock_t *sb = journal->j_superblock;
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struct buffer_head *bh = journal->j_sb_buffer;
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/*
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* As a special case, if the on-disk copy is already marked as needing
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* no recovery (s_start == 0) and there are no outstanding transactions
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* in the filesystem, then we can safely defer the superblock update
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* until the next commit by setting JBD2_FLUSHED. This avoids
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* no recovery (s_start == 0), then we can safely defer the superblock
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* update until the next commit by setting JBD2_FLUSHED. This avoids
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* attempting a write to a potential-readonly device.
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*/
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if (sb->s_start == 0 && journal->j_tail_sequence ==
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journal->j_transaction_sequence) {
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if (sb->s_start == 0) {
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jbd_debug(1, "JBD2: Skipping superblock update on recovered sb "
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"(start %ld, seq %d, errno %d)\n",
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journal->j_tail, journal->j_tail_sequence,
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journal->j_errno);
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goto out;
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journal->j_flags |= JBD2_FLUSHED;
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} else {
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/* Add the dynamic fields and write it to disk. */
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jbd2_journal_update_sb_log_tail(journal);
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}
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return jbd2_journal_start_thread(journal);
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}
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static void jbd2_write_superblock(journal_t *journal)
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{
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struct buffer_head *bh = journal->j_sb_buffer;
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trace_jbd2_write_superblock(journal);
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if (buffer_write_io_error(bh)) {
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/*
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* Oh, dear. A previous attempt to write the journal
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@ -1160,49 +1150,98 @@ void jbd2_journal_update_superblock(journal_t *journal, int wait)
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set_buffer_uptodate(bh);
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}
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BUFFER_TRACE(bh, "marking dirty");
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mark_buffer_dirty(bh);
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sync_dirty_buffer(bh);
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if (buffer_write_io_error(bh)) {
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printk(KERN_ERR "JBD2: I/O error detected "
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"when updating journal superblock for %s.\n",
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journal->j_devname);
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clear_buffer_write_io_error(bh);
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set_buffer_uptodate(bh);
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}
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}
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/**
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* jbd2_journal_update_sb_log_tail() - Update log tail in journal sb on disk.
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* @journal: The journal to update.
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*
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* Update a journal's superblock information about log tail and write it to
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* disk, waiting for the IO to complete.
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*/
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void jbd2_journal_update_sb_log_tail(journal_t *journal)
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{
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journal_superblock_t *sb = journal->j_superblock;
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read_lock(&journal->j_state_lock);
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jbd_debug(1, "JBD2: updating superblock (start %ld, seq %d, errno %d)\n",
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journal->j_tail, journal->j_tail_sequence, journal->j_errno);
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jbd_debug(1, "JBD2: updating superblock (start %ld, seq %d)\n",
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journal->j_tail, journal->j_tail_sequence);
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sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
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sb->s_start = cpu_to_be32(journal->j_tail);
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read_unlock(&journal->j_state_lock);
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jbd2_write_superblock(journal);
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/* Log is no longer empty */
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write_lock(&journal->j_state_lock);
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WARN_ON(!sb->s_sequence);
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journal->j_flags &= ~JBD2_FLUSHED;
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write_unlock(&journal->j_state_lock);
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}
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/**
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* jbd2_mark_journal_empty() - Mark on disk journal as empty.
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* @journal: The journal to update.
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*
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* Update a journal's dynamic superblock fields to show that journal is empty.
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* Write updated superblock to disk waiting for IO to complete.
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*/
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static void jbd2_mark_journal_empty(journal_t *journal)
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{
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journal_superblock_t *sb = journal->j_superblock;
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read_lock(&journal->j_state_lock);
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jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n",
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journal->j_tail_sequence);
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sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
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sb->s_start = cpu_to_be32(0);
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read_unlock(&journal->j_state_lock);
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jbd2_write_superblock(journal);
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/* Log is no longer empty */
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write_lock(&journal->j_state_lock);
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journal->j_flags |= JBD2_FLUSHED;
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write_unlock(&journal->j_state_lock);
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}
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/**
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* jbd2_journal_update_sb_errno() - Update error in the journal.
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* @journal: The journal to update.
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*
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* Update a journal's errno. Write updated superblock to disk waiting for IO
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* to complete.
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*/
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static void jbd2_journal_update_sb_errno(journal_t *journal)
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{
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journal_superblock_t *sb = journal->j_superblock;
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read_lock(&journal->j_state_lock);
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jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",
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journal->j_errno);
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sb->s_errno = cpu_to_be32(journal->j_errno);
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read_unlock(&journal->j_state_lock);
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BUFFER_TRACE(bh, "marking dirty");
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mark_buffer_dirty(bh);
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if (wait) {
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sync_dirty_buffer(bh);
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if (buffer_write_io_error(bh)) {
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printk(KERN_ERR "JBD2: I/O error detected "
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"when updating journal superblock for %s.\n",
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journal->j_devname);
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clear_buffer_write_io_error(bh);
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set_buffer_uptodate(bh);
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}
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} else
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write_dirty_buffer(bh, WRITE);
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trace_jbd2_update_superblock_end(journal, wait);
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out:
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/* If we have just flushed the log (by marking s_start==0), then
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* any future commit will have to be careful to update the
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* superblock again to re-record the true start of the log. */
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write_lock(&journal->j_state_lock);
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if (sb->s_start)
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journal->j_flags &= ~JBD2_FLUSHED;
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else
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journal->j_flags |= JBD2_FLUSHED;
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write_unlock(&journal->j_state_lock);
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jbd2_write_superblock(journal);
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}
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/*
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* Read the superblock for a given journal, performing initial
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* validation of the format.
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*/
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static int journal_get_superblock(journal_t *journal)
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{
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struct buffer_head *bh;
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@ -1395,15 +1434,10 @@ int jbd2_journal_destroy(journal_t *journal)
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spin_unlock(&journal->j_list_lock);
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if (journal->j_sb_buffer) {
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if (!is_journal_aborted(journal)) {
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/* We can now mark the journal as empty. */
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journal->j_tail = 0;
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journal->j_tail_sequence =
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++journal->j_transaction_sequence;
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jbd2_journal_update_superblock(journal, 1);
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} else {
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if (!is_journal_aborted(journal))
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jbd2_mark_journal_empty(journal);
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else
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err = -EIO;
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}
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brelse(journal->j_sb_buffer);
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}
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@ -1562,7 +1596,6 @@ int jbd2_journal_flush(journal_t *journal)
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{
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int err = 0;
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transaction_t *transaction = NULL;
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unsigned long old_tail;
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write_lock(&journal->j_state_lock);
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@ -1604,14 +1637,8 @@ int jbd2_journal_flush(journal_t *journal)
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* the magic code for a fully-recovered superblock. Any future
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* commits of data to the journal will restore the current
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* s_start value. */
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jbd2_mark_journal_empty(journal);
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write_lock(&journal->j_state_lock);
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old_tail = journal->j_tail;
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journal->j_tail = 0;
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write_unlock(&journal->j_state_lock);
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jbd2_journal_update_superblock(journal, 1);
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write_lock(&journal->j_state_lock);
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journal->j_tail = old_tail;
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J_ASSERT(!journal->j_running_transaction);
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J_ASSERT(!journal->j_committing_transaction);
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J_ASSERT(!journal->j_checkpoint_transactions);
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@ -1652,7 +1679,7 @@ int jbd2_journal_wipe(journal_t *journal, int write)
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err = jbd2_journal_skip_recovery(journal);
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if (write)
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jbd2_journal_update_superblock(journal, 1);
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jbd2_mark_journal_empty(journal);
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no_recovery:
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return err;
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@ -1702,7 +1729,7 @@ static void __journal_abort_soft (journal_t *journal, int errno)
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__jbd2_journal_abort_hard(journal);
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if (errno)
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jbd2_journal_update_superblock(journal, 1);
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jbd2_journal_update_sb_errno(journal);
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}
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/**
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@ -1087,7 +1087,7 @@ extern int jbd2_journal_destroy (journal_t *);
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extern int jbd2_journal_recover (journal_t *journal);
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extern int jbd2_journal_wipe (journal_t *, int);
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extern int jbd2_journal_skip_recovery (journal_t *);
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extern void jbd2_journal_update_superblock (journal_t *, int);
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extern void jbd2_journal_update_sb_log_tail (journal_t *);
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extern void __jbd2_journal_abort_hard (journal_t *);
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extern void jbd2_journal_abort (journal_t *, int);
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extern int jbd2_journal_errno (journal_t *);
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@ -236,25 +236,21 @@ TRACE_EVENT(jbd2_cleanup_journal_tail,
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__entry->block_nr, __entry->freed)
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);
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TRACE_EVENT(jbd2_update_superblock_end,
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TRACE_EVENT(jbd2_write_superblock,
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TP_PROTO(journal_t *journal, int wait),
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TP_PROTO(journal_t *journal),
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TP_ARGS(journal, wait),
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TP_ARGS(journal),
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TP_STRUCT__entry(
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__field( dev_t, dev )
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__field( int, wait )
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),
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TP_fast_assign(
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__entry->dev = journal->j_fs_dev->bd_dev;
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__entry->wait = wait;
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),
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TP_printk("dev %d,%d wait %d",
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MAJOR(__entry->dev), MINOR(__entry->dev),
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__entry->wait)
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TP_printk("dev %d,%d", MAJOR(__entry->dev), MINOR(__entry->dev))
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);
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#endif /* _TRACE_JBD2_H */
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