transaction.c 65.0 KB
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/*
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 * linux/fs/jbd2/transaction.c
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 *
 * 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.
 *
 * Generic filesystem transaction handling code; part of the ext2fs
 * journaling system.
 *
 * This file manages transactions (compound commits managed by the
 * journaling code) and handles (individual atomic operations by the
 * filesystem).
 */

#include <linux/time.h>
#include <linux/fs.h>
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#include <linux/jbd2.h>
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#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/highmem.h>

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static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);

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/*
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 * jbd2_get_transaction: obtain a new transaction_t object.
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 *
 * Simply allocate and initialise a new transaction.  Create it in
 * RUNNING state and add it to the current journal (which should not
 * have an existing running transaction: we only make a new transaction
 * once we have started to commit the old one).
 *
 * Preconditions:
 *	The journal MUST be locked.  We don't perform atomic mallocs on the
 *	new transaction	and we can't block without protecting against other
 *	processes trying to touch the journal while it is in transition.
 *
 */

static transaction_t *
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jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
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{
	transaction->t_journal = journal;
	transaction->t_state = T_RUNNING;
	transaction->t_tid = journal->j_transaction_sequence++;
	transaction->t_expires = jiffies + journal->j_commit_interval;
	spin_lock_init(&transaction->t_handle_lock);

	/* Set up the commit timer for the new transaction. */
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	journal->j_commit_timer.expires = round_jiffies(transaction->t_expires);
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	add_timer(&journal->j_commit_timer);

	J_ASSERT(journal->j_running_transaction == NULL);
	journal->j_running_transaction = transaction;
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	transaction->t_max_wait = 0;
	transaction->t_start = jiffies;
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	return transaction;
}

/*
 * Handle management.
 *
 * A handle_t is an object which represents a single atomic update to a
 * filesystem, and which tracks all of the modifications which form part
 * of that one update.
 */

/*
 * start_this_handle: Given a handle, deal with any locking or stalling
 * needed to make sure that there is enough journal space for the handle
 * to begin.  Attach the handle to a transaction and set up the
 * transaction's buffer credits.
 */

static int start_this_handle(journal_t *journal, handle_t *handle)
{
	transaction_t *transaction;
	int needed;
	int nblocks = handle->h_buffer_credits;
	transaction_t *new_transaction = NULL;
	int ret = 0;
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	unsigned long ts = jiffies;
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	if (nblocks > journal->j_max_transaction_buffers) {
		printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
		       current->comm, nblocks,
		       journal->j_max_transaction_buffers);
		ret = -ENOSPC;
		goto out;
	}

alloc_transaction:
	if (!journal->j_running_transaction) {
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		new_transaction = kzalloc(sizeof(*new_transaction),
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						GFP_NOFS|__GFP_NOFAIL);
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		if (!new_transaction) {
			ret = -ENOMEM;
			goto out;
		}
	}

	jbd_debug(3, "New handle %p going live.\n", handle);

repeat:

	/*
	 * We need to hold j_state_lock until t_updates has been incremented,
	 * for proper journal barrier handling
	 */
	spin_lock(&journal->j_state_lock);
repeat_locked:
	if (is_journal_aborted(journal) ||
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	    (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
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		spin_unlock(&journal->j_state_lock);
		ret = -EROFS;
		goto out;
	}

	/* Wait on the journal's transaction barrier if necessary */
	if (journal->j_barrier_count) {
		spin_unlock(&journal->j_state_lock);
		wait_event(journal->j_wait_transaction_locked,
				journal->j_barrier_count == 0);
		goto repeat;
	}

	if (!journal->j_running_transaction) {
		if (!new_transaction) {
			spin_unlock(&journal->j_state_lock);
			goto alloc_transaction;
		}
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		jbd2_get_transaction(journal, new_transaction);
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		new_transaction = NULL;
	}

	transaction = journal->j_running_transaction;

	/*
	 * If the current transaction is locked down for commit, wait for the
	 * lock to be released.
	 */
	if (transaction->t_state == T_LOCKED) {
		DEFINE_WAIT(wait);

		prepare_to_wait(&journal->j_wait_transaction_locked,
					&wait, TASK_UNINTERRUPTIBLE);
		spin_unlock(&journal->j_state_lock);
		schedule();
		finish_wait(&journal->j_wait_transaction_locked, &wait);
		goto repeat;
	}

	/*
	 * If there is not enough space left in the log to write all potential
	 * buffers requested by this operation, we need to stall pending a log
	 * checkpoint to free some more log space.
	 */
	spin_lock(&transaction->t_handle_lock);
	needed = transaction->t_outstanding_credits + nblocks;

	if (needed > journal->j_max_transaction_buffers) {
		/*
		 * If the current transaction is already too large, then start
		 * to commit it: we can then go back and attach this handle to
		 * a new transaction.
		 */
		DEFINE_WAIT(wait);

		jbd_debug(2, "Handle %p starting new commit...\n", handle);
		spin_unlock(&transaction->t_handle_lock);
		prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
				TASK_UNINTERRUPTIBLE);
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		__jbd2_log_start_commit(journal, transaction->t_tid);
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		spin_unlock(&journal->j_state_lock);
		schedule();
		finish_wait(&journal->j_wait_transaction_locked, &wait);
		goto repeat;
	}

	/*
	 * The commit code assumes that it can get enough log space
	 * without forcing a checkpoint.  This is *critical* for
	 * correctness: a checkpoint of a buffer which is also
	 * associated with a committing transaction creates a deadlock,
	 * so commit simply cannot force through checkpoints.
	 *
	 * We must therefore ensure the necessary space in the journal
	 * *before* starting to dirty potentially checkpointed buffers
	 * in the new transaction.
	 *
	 * The worst part is, any transaction currently committing can
	 * reduce the free space arbitrarily.  Be careful to account for
	 * those buffers when checkpointing.
	 */

	/*
	 * @@@ AKPM: This seems rather over-defensive.  We're giving commit
	 * a _lot_ of headroom: 1/4 of the journal plus the size of
	 * the committing transaction.  Really, we only need to give it
	 * committing_transaction->t_outstanding_credits plus "enough" for
	 * the log control blocks.
	 * Also, this test is inconsitent with the matching one in
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	 * jbd2_journal_extend().
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	 */
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	if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) {
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		jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
		spin_unlock(&transaction->t_handle_lock);
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		__jbd2_log_wait_for_space(journal);
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		goto repeat_locked;
	}

	/* OK, account for the buffers that this operation expects to
	 * use and add the handle to the running transaction. */

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	if (time_after(transaction->t_start, ts)) {
		ts = jbd2_time_diff(ts, transaction->t_start);
		if (ts > transaction->t_max_wait)
			transaction->t_max_wait = ts;
	}

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	handle->h_transaction = transaction;
	transaction->t_outstanding_credits += nblocks;
	transaction->t_updates++;
	transaction->t_handle_count++;
	jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
		  handle, nblocks, transaction->t_outstanding_credits,
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		  __jbd2_log_space_left(journal));
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	spin_unlock(&transaction->t_handle_lock);
	spin_unlock(&journal->j_state_lock);
out:
	if (unlikely(new_transaction))		/* It's usually NULL */
		kfree(new_transaction);
	return ret;
}

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static struct lock_class_key jbd2_handle_key;

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/* Allocate a new handle.  This should probably be in a slab... */
static handle_t *new_handle(int nblocks)
{
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	handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
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	if (!handle)
		return NULL;
	memset(handle, 0, sizeof(*handle));
	handle->h_buffer_credits = nblocks;
	handle->h_ref = 1;

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	lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle",
						&jbd2_handle_key, 0);

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	return handle;
}

/**
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 * handle_t *jbd2_journal_start() - Obtain a new handle.
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 * @journal: Journal to start transaction on.
 * @nblocks: number of block buffer we might modify
 *
 * We make sure that the transaction can guarantee at least nblocks of
 * modified buffers in the log.  We block until the log can guarantee
 * that much space.
 *
 * This function is visible to journal users (like ext3fs), so is not
 * called with the journal already locked.
 *
 * Return a pointer to a newly allocated handle, or NULL on failure
 */
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handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
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{
	handle_t *handle = journal_current_handle();
	int err;

	if (!journal)
		return ERR_PTR(-EROFS);

	if (handle) {
		J_ASSERT(handle->h_transaction->t_journal == journal);
		handle->h_ref++;
		return handle;
	}

	handle = new_handle(nblocks);
	if (!handle)
		return ERR_PTR(-ENOMEM);

	current->journal_info = handle;

	err = start_this_handle(journal, handle);
	if (err < 0) {
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		jbd2_free_handle(handle);
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		current->journal_info = NULL;
		handle = ERR_PTR(err);
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		goto out;
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	}
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	lock_acquire(&handle->h_lockdep_map, 0, 0, 0, 2, _THIS_IP_);
out:
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	return handle;
}

/**
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 * int jbd2_journal_extend() - extend buffer credits.
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 * @handle:  handle to 'extend'
 * @nblocks: nr blocks to try to extend by.
 *
 * Some transactions, such as large extends and truncates, can be done
 * atomically all at once or in several stages.  The operation requests
 * a credit for a number of buffer modications in advance, but can
 * extend its credit if it needs more.
 *
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 * jbd2_journal_extend tries to give the running handle more buffer credits.
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 * It does not guarantee that allocation - this is a best-effort only.
 * The calling process MUST be able to deal cleanly with a failure to
 * extend here.
 *
 * Return 0 on success, non-zero on failure.
 *
 * return code < 0 implies an error
 * return code > 0 implies normal transaction-full status.
 */
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int jbd2_journal_extend(handle_t *handle, int nblocks)
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{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	int result;
	int wanted;

	result = -EIO;
	if (is_handle_aborted(handle))
		goto out;

	result = 1;

	spin_lock(&journal->j_state_lock);

	/* Don't extend a locked-down transaction! */
	if (handle->h_transaction->t_state != T_RUNNING) {
		jbd_debug(3, "denied handle %p %d blocks: "
			  "transaction not running\n", handle, nblocks);
		goto error_out;
	}

	spin_lock(&transaction->t_handle_lock);
	wanted = transaction->t_outstanding_credits + nblocks;

	if (wanted > journal->j_max_transaction_buffers) {
		jbd_debug(3, "denied handle %p %d blocks: "
			  "transaction too large\n", handle, nblocks);
		goto unlock;
	}

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	if (wanted > __jbd2_log_space_left(journal)) {
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		jbd_debug(3, "denied handle %p %d blocks: "
			  "insufficient log space\n", handle, nblocks);
		goto unlock;
	}

	handle->h_buffer_credits += nblocks;
	transaction->t_outstanding_credits += nblocks;
	result = 0;

	jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
unlock:
	spin_unlock(&transaction->t_handle_lock);
error_out:
	spin_unlock(&journal->j_state_lock);
out:
	return result;
}


/**
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 * int jbd2_journal_restart() - restart a handle .
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 * @handle:  handle to restart
 * @nblocks: nr credits requested
 *
 * Restart a handle for a multi-transaction filesystem
 * operation.
 *
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 * If the jbd2_journal_extend() call above fails to grant new buffer credits
 * to a running handle, a call to jbd2_journal_restart will commit the
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 * handle's transaction so far and reattach the handle to a new
 * transaction capabable of guaranteeing the requested number of
 * credits.
 */

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int jbd2_journal_restart(handle_t *handle, int nblocks)
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{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	int ret;

	/* If we've had an abort of any type, don't even think about
	 * actually doing the restart! */
	if (is_handle_aborted(handle))
		return 0;

	/*
	 * First unlink the handle from its current transaction, and start the
	 * commit on that.
	 */
	J_ASSERT(transaction->t_updates > 0);
	J_ASSERT(journal_current_handle() == handle);

	spin_lock(&journal->j_state_lock);
	spin_lock(&transaction->t_handle_lock);
	transaction->t_outstanding_credits -= handle->h_buffer_credits;
	transaction->t_updates--;

	if (!transaction->t_updates)
		wake_up(&journal->j_wait_updates);
	spin_unlock(&transaction->t_handle_lock);

	jbd_debug(2, "restarting handle %p\n", handle);
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	__jbd2_log_start_commit(journal, transaction->t_tid);
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	spin_unlock(&journal->j_state_lock);

	handle->h_buffer_credits = nblocks;
	ret = start_this_handle(journal, handle);
	return ret;
}


/**
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 * void jbd2_journal_lock_updates () - establish a transaction barrier.
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 * @journal:  Journal to establish a barrier on.
 *
 * This locks out any further updates from being started, and blocks
 * until all existing updates have completed, returning only once the
 * journal is in a quiescent state with no updates running.
 *
 * The journal lock should not be held on entry.
 */
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void jbd2_journal_lock_updates(journal_t *journal)
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{
	DEFINE_WAIT(wait);

	spin_lock(&journal->j_state_lock);
	++journal->j_barrier_count;

	/* Wait until there are no running updates */
	while (1) {
		transaction_t *transaction = journal->j_running_transaction;

		if (!transaction)
			break;

		spin_lock(&transaction->t_handle_lock);
		if (!transaction->t_updates) {
			spin_unlock(&transaction->t_handle_lock);
			break;
		}
		prepare_to_wait(&journal->j_wait_updates, &wait,
				TASK_UNINTERRUPTIBLE);
		spin_unlock(&transaction->t_handle_lock);
		spin_unlock(&journal->j_state_lock);
		schedule();
		finish_wait(&journal->j_wait_updates, &wait);
		spin_lock(&journal->j_state_lock);
	}
	spin_unlock(&journal->j_state_lock);

	/*
	 * We have now established a barrier against other normal updates, but
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	 * we also need to barrier against other jbd2_journal_lock_updates() calls
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	 * to make sure that we serialise special journal-locked operations
	 * too.
	 */
	mutex_lock(&journal->j_barrier);
}

/**
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 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
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 * @journal:  Journal to release the barrier on.
 *
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 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
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 *
 * Should be called without the journal lock held.
 */
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void jbd2_journal_unlock_updates (journal_t *journal)
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{
	J_ASSERT(journal->j_barrier_count != 0);

	mutex_unlock(&journal->j_barrier);
	spin_lock(&journal->j_state_lock);
	--journal->j_barrier_count;
	spin_unlock(&journal->j_state_lock);
	wake_up(&journal->j_wait_transaction_locked);
}

/*
 * Report any unexpected dirty buffers which turn up.  Normally those
 * indicate an error, but they can occur if the user is running (say)
 * tune2fs to modify the live filesystem, so we need the option of
 * continuing as gracefully as possible.  #
 *
 * The caller should already hold the journal lock and
 * j_list_lock spinlock: most callers will need those anyway
 * in order to probe the buffer's journaling state safely.
 */
static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
{
	int jlist;

	/* If this buffer is one which might reasonably be dirty
	 * --- ie. data, or not part of this journal --- then
	 * we're OK to leave it alone, but otherwise we need to
	 * move the dirty bit to the journal's own internal
	 * JBDDirty bit. */
	jlist = jh->b_jlist;

	if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
	    jlist == BJ_Shadow || jlist == BJ_Forget) {
		struct buffer_head *bh = jh2bh(jh);

		if (test_clear_buffer_dirty(bh))
			set_buffer_jbddirty(bh);
	}
}

/*
 * If the buffer is already part of the current transaction, then there
 * is nothing we need to do.  If it is already part of a prior
 * transaction which we are still committing to disk, then we need to
 * make sure that we do not overwrite the old copy: we do copy-out to
 * preserve the copy going to disk.  We also account the buffer against
 * the handle's metadata buffer credits (unless the buffer is already
 * part of the transaction, that is).
 *
 */
static int
do_get_write_access(handle_t *handle, struct journal_head *jh,
			int force_copy)
{
	struct buffer_head *bh;
	transaction_t *transaction;
	journal_t *journal;
	int error;
	char *frozen_buffer = NULL;
	int need_copy = 0;

	if (is_handle_aborted(handle))
		return -EROFS;

	transaction = handle->h_transaction;
	journal = transaction->t_journal;

	jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);

	JBUFFER_TRACE(jh, "entry");
repeat:
	bh = jh2bh(jh);

	/* @@@ Need to check for errors here at some point. */

	lock_buffer(bh);
	jbd_lock_bh_state(bh);

	/* We now hold the buffer lock so it is safe to query the buffer
	 * state.  Is the buffer dirty?
	 *
	 * If so, there are two possibilities.  The buffer may be
	 * non-journaled, and undergoing a quite legitimate writeback.
	 * Otherwise, it is journaled, and we don't expect dirty buffers
	 * in that state (the buffers should be marked JBD_Dirty
	 * instead.)  So either the IO is being done under our own
	 * control and this is a bug, or it's a third party IO such as
	 * dump(8) (which may leave the buffer scheduled for read ---
	 * ie. locked but not dirty) or tune2fs (which may actually have
	 * the buffer dirtied, ugh.)  */

	if (buffer_dirty(bh)) {
		/*
		 * First question: is this buffer already part of the current
		 * transaction or the existing committing transaction?
		 */
		if (jh->b_transaction) {
			J_ASSERT_JH(jh,
				jh->b_transaction == transaction ||
				jh->b_transaction ==
					journal->j_committing_transaction);
			if (jh->b_next_transaction)
				J_ASSERT_JH(jh, jh->b_next_transaction ==
							transaction);
		}
		/*
		 * In any case we need to clean the dirty flag and we must
		 * do it under the buffer lock to be sure we don't race
		 * with running write-out.
		 */
		JBUFFER_TRACE(jh, "Unexpected dirty buffer");
		jbd_unexpected_dirty_buffer(jh);
	}

	unlock_buffer(bh);

	error = -EROFS;
	if (is_handle_aborted(handle)) {
		jbd_unlock_bh_state(bh);
		goto out;
	}
	error = 0;

	/*
	 * The buffer is already part of this transaction if b_transaction or
	 * b_next_transaction points to it
	 */
	if (jh->b_transaction == transaction ||
	    jh->b_next_transaction == transaction)
		goto done;

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	/*
	 * this is the first time this transaction is touching this buffer,
	 * reset the modified flag
	 */
       jh->b_modified = 0;

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	/*
	 * If there is already a copy-out version of this buffer, then we don't
	 * need to make another one
	 */
	if (jh->b_frozen_data) {
		JBUFFER_TRACE(jh, "has frozen data");
		J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
		jh->b_next_transaction = transaction;
		goto done;
	}

	/* Is there data here we need to preserve? */

	if (jh->b_transaction && jh->b_transaction != transaction) {
		JBUFFER_TRACE(jh, "owned by older transaction");
		J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
		J_ASSERT_JH(jh, jh->b_transaction ==
					journal->j_committing_transaction);

		/* There is one case we have to be very careful about.
		 * If the committing transaction is currently writing
		 * this buffer out to disk and has NOT made a copy-out,
		 * then we cannot modify the buffer contents at all
		 * right now.  The essence of copy-out is that it is the
		 * extra copy, not the primary copy, which gets
		 * journaled.  If the primary copy is already going to
		 * disk then we cannot do copy-out here. */

		if (jh->b_jlist == BJ_Shadow) {
			DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
			wait_queue_head_t *wqh;

			wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);

			JBUFFER_TRACE(jh, "on shadow: sleep");
			jbd_unlock_bh_state(bh);
			/* commit wakes up all shadow buffers after IO */
			for ( ; ; ) {
				prepare_to_wait(wqh, &wait.wait,
						TASK_UNINTERRUPTIBLE);
				if (jh->b_jlist != BJ_Shadow)
					break;
				schedule();
			}
			finish_wait(wqh, &wait.wait);
			goto repeat;
		}

		/* Only do the copy if the currently-owning transaction
		 * still needs it.  If it is on the Forget list, the
		 * committing transaction is past that stage.  The
		 * buffer had better remain locked during the kmalloc,
		 * but that should be true --- we hold the journal lock
		 * still and the buffer is already on the BUF_JOURNAL
		 * list so won't be flushed.
		 *
		 * Subtle point, though: if this is a get_undo_access,
		 * then we will be relying on the frozen_data to contain
		 * the new value of the committed_data record after the
		 * transaction, so we HAVE to force the frozen_data copy
		 * in that case. */

		if (jh->b_jlist != BJ_Forget || force_copy) {
			JBUFFER_TRACE(jh, "generate frozen data");
			if (!frozen_buffer) {
				JBUFFER_TRACE(jh, "allocate memory for buffer");
				jbd_unlock_bh_state(bh);
				frozen_buffer =
M
Mingming Cao 已提交
693
					jbd2_alloc(jh2bh(jh)->b_size,
694 695 696 697
							 GFP_NOFS);
				if (!frozen_buffer) {
					printk(KERN_EMERG
					       "%s: OOM for frozen_buffer\n",
698
					       __func__);
699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724
					JBUFFER_TRACE(jh, "oom!");
					error = -ENOMEM;
					jbd_lock_bh_state(bh);
					goto done;
				}
				goto repeat;
			}
			jh->b_frozen_data = frozen_buffer;
			frozen_buffer = NULL;
			need_copy = 1;
		}
		jh->b_next_transaction = transaction;
	}


	/*
	 * Finally, if the buffer is not journaled right now, we need to make
	 * sure it doesn't get written to disk before the caller actually
	 * commits the new data
	 */
	if (!jh->b_transaction) {
		JBUFFER_TRACE(jh, "no transaction");
		J_ASSERT_JH(jh, !jh->b_next_transaction);
		jh->b_transaction = transaction;
		JBUFFER_TRACE(jh, "file as BJ_Reserved");
		spin_lock(&journal->j_list_lock);
725
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748
		spin_unlock(&journal->j_list_lock);
	}

done:
	if (need_copy) {
		struct page *page;
		int offset;
		char *source;

		J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
			    "Possible IO failure.\n");
		page = jh2bh(jh)->b_page;
		offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
		source = kmap_atomic(page, KM_USER0);
		memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
		kunmap_atomic(source, KM_USER0);
	}
	jbd_unlock_bh_state(bh);

	/*
	 * If we are about to journal a buffer, then any revoke pending on it is
	 * no longer valid
	 */
749
	jbd2_journal_cancel_revoke(handle, jh);
750 751 752

out:
	if (unlikely(frozen_buffer))	/* It's usually NULL */
M
Mingming Cao 已提交
753
		jbd2_free(frozen_buffer, bh->b_size);
754 755 756 757 758 759

	JBUFFER_TRACE(jh, "exit");
	return error;
}

/**
760
 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
761 762 763 764 765 766 767 768 769 770
 * @handle: transaction to add buffer modifications to
 * @bh:     bh to be used for metadata writes
 * @credits: variable that will receive credits for the buffer
 *
 * Returns an error code or 0 on success.
 *
 * In full data journalling mode the buffer may be of type BJ_AsyncData,
 * because we're write()ing a buffer which is also part of a shared mapping.
 */

771
int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
772
{
773
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
774 775 776 777 778 779
	int rc;

	/* We do not want to get caught playing with fields which the
	 * log thread also manipulates.  Make sure that the buffer
	 * completes any outstanding IO before proceeding. */
	rc = do_get_write_access(handle, jh, 0);
780
	jbd2_journal_put_journal_head(jh);
781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797
	return rc;
}


/*
 * When the user wants to journal a newly created buffer_head
 * (ie. getblk() returned a new buffer and we are going to populate it
 * manually rather than reading off disk), then we need to keep the
 * buffer_head locked until it has been completely filled with new
 * data.  In this case, we should be able to make the assertion that
 * the bh is not already part of an existing transaction.
 *
 * The buffer should already be locked by the caller by this point.
 * There is no lock ranking violation: it was a newly created,
 * unlocked buffer beforehand. */

/**
798
 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
799 800 801 802 803
 * @handle: transaction to new buffer to
 * @bh: new buffer.
 *
 * Call this if you create a new bh.
 */
804
int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
805 806 807
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
808
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836
	int err;

	jbd_debug(5, "journal_head %p\n", jh);
	err = -EROFS;
	if (is_handle_aborted(handle))
		goto out;
	err = 0;

	JBUFFER_TRACE(jh, "entry");
	/*
	 * The buffer may already belong to this transaction due to pre-zeroing
	 * in the filesystem's new_block code.  It may also be on the previous,
	 * committing transaction's lists, but it HAS to be in Forget state in
	 * that case: the transaction must have deleted the buffer for it to be
	 * reused here.
	 */
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);
	J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
		jh->b_transaction == NULL ||
		(jh->b_transaction == journal->j_committing_transaction &&
			  jh->b_jlist == BJ_Forget)));

	J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
	J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));

	if (jh->b_transaction == NULL) {
		jh->b_transaction = transaction;
837 838 839 840

		/* first access by this transaction */
		jh->b_modified = 0;

841
		JBUFFER_TRACE(jh, "file as BJ_Reserved");
842
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
843
	} else if (jh->b_transaction == journal->j_committing_transaction) {
844 845 846
		/* first access by this transaction */
		jh->b_modified = 0;

847 848 849 850 851 852 853 854 855 856 857 858 859 860
		JBUFFER_TRACE(jh, "set next transaction");
		jh->b_next_transaction = transaction;
	}
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(bh);

	/*
	 * akpm: I added this.  ext3_alloc_branch can pick up new indirect
	 * blocks which contain freed but then revoked metadata.  We need
	 * to cancel the revoke in case we end up freeing it yet again
	 * and the reallocating as data - this would cause a second revoke,
	 * which hits an assertion error.
	 */
	JBUFFER_TRACE(jh, "cancelling revoke");
861 862
	jbd2_journal_cancel_revoke(handle, jh);
	jbd2_journal_put_journal_head(jh);
863 864 865 866 867
out:
	return err;
}

/**
868
 * int jbd2_journal_get_undo_access() -  Notify intent to modify metadata with
869 870 871 872 873 874 875 876 877 878 879 880
 *     non-rewindable consequences
 * @handle: transaction
 * @bh: buffer to undo
 * @credits: store the number of taken credits here (if not NULL)
 *
 * Sometimes there is a need to distinguish between metadata which has
 * been committed to disk and that which has not.  The ext3fs code uses
 * this for freeing and allocating space, we have to make sure that we
 * do not reuse freed space until the deallocation has been committed,
 * since if we overwrote that space we would make the delete
 * un-rewindable in case of a crash.
 *
881
 * To deal with that, jbd2_journal_get_undo_access requests write access to a
882 883 884 885 886 887 888 889 890 891 892 893
 * buffer for parts of non-rewindable operations such as delete
 * operations on the bitmaps.  The journaling code must keep a copy of
 * the buffer's contents prior to the undo_access call until such time
 * as we know that the buffer has definitely been committed to disk.
 *
 * We never need to know which transaction the committed data is part
 * of, buffers touched here are guaranteed to be dirtied later and so
 * will be committed to a new transaction in due course, at which point
 * we can discard the old committed data pointer.
 *
 * Returns error number or 0 on success.
 */
894
int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
895 896
{
	int err;
897
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
898 899 900 901 902 903 904 905 906 907 908 909 910 911 912
	char *committed_data = NULL;

	JBUFFER_TRACE(jh, "entry");

	/*
	 * Do this first --- it can drop the journal lock, so we want to
	 * make sure that obtaining the committed_data is done
	 * atomically wrt. completion of any outstanding commits.
	 */
	err = do_get_write_access(handle, jh, 1);
	if (err)
		goto out;

repeat:
	if (!jh->b_committed_data) {
M
Mingming Cao 已提交
913
		committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
914 915
		if (!committed_data) {
			printk(KERN_EMERG "%s: No memory for committed data\n",
916
				__func__);
917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937
			err = -ENOMEM;
			goto out;
		}
	}

	jbd_lock_bh_state(bh);
	if (!jh->b_committed_data) {
		/* Copy out the current buffer contents into the
		 * preserved, committed copy. */
		JBUFFER_TRACE(jh, "generate b_committed data");
		if (!committed_data) {
			jbd_unlock_bh_state(bh);
			goto repeat;
		}

		jh->b_committed_data = committed_data;
		committed_data = NULL;
		memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
	}
	jbd_unlock_bh_state(bh);
out:
938
	jbd2_journal_put_journal_head(jh);
939
	if (unlikely(committed_data))
M
Mingming Cao 已提交
940
		jbd2_free(committed_data, bh->b_size);
941 942 943 944
	return err;
}

/**
945
 * int jbd2_journal_dirty_data() -  mark a buffer as containing dirty data which
946 947 948 949 950 951 952 953 954 955
 *                             needs to be flushed before we can commit the
 *                             current transaction.
 * @handle: transaction
 * @bh: bufferhead to mark
 *
 * The buffer is placed on the transaction's data list and is marked as
 * belonging to the transaction.
 *
 * Returns error number or 0 on success.
 *
956
 * jbd2_journal_dirty_data() can be called via page_launder->ext3_writepage
957 958
 * by kswapd.
 */
959
int jbd2_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
960 961 962 963 964 965 966 967
{
	journal_t *journal = handle->h_transaction->t_journal;
	int need_brelse = 0;
	struct journal_head *jh;

	if (is_handle_aborted(handle))
		return 0;

968
	jh = jbd2_journal_add_journal_head(bh);
969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999
	JBUFFER_TRACE(jh, "entry");

	/*
	 * The buffer could *already* be dirty.  Writeout can start
	 * at any time.
	 */
	jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);

	/*
	 * What if the buffer is already part of a running transaction?
	 *
	 * There are two cases:
	 * 1) It is part of the current running transaction.  Refile it,
	 *    just in case we have allocated it as metadata, deallocated
	 *    it, then reallocated it as data.
	 * 2) It is part of the previous, still-committing transaction.
	 *    If all we want to do is to guarantee that the buffer will be
	 *    written to disk before this new transaction commits, then
	 *    being sure that the *previous* transaction has this same
	 *    property is sufficient for us!  Just leave it on its old
	 *    transaction.
	 *
	 * In case (2), the buffer must not already exist as metadata
	 * --- that would violate write ordering (a transaction is free
	 * to write its data at any point, even before the previous
	 * committing transaction has committed).  The caller must
	 * never, ever allow this to happen: there's nothing we can do
	 * about it in this layer.
	 */
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);
1000 1001 1002 1003 1004 1005 1006

	/* Now that we have bh_state locked, are we really still mapped? */
	if (!buffer_mapped(bh)) {
		JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
		goto no_journal;
	}

1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023
	if (jh->b_transaction) {
		JBUFFER_TRACE(jh, "has transaction");
		if (jh->b_transaction != handle->h_transaction) {
			JBUFFER_TRACE(jh, "belongs to older transaction");
			J_ASSERT_JH(jh, jh->b_transaction ==
					journal->j_committing_transaction);

			/* @@@ IS THIS TRUE  ? */
			/*
			 * Not any more.  Scenario: someone does a write()
			 * in data=journal mode.  The buffer's transaction has
			 * moved into commit.  Then someone does another
			 * write() to the file.  We do the frozen data copyout
			 * and set b_next_transaction to point to j_running_t.
			 * And while we're in that state, someone does a
			 * writepage() in an attempt to pageout the same area
			 * of the file via a shared mapping.  At present that
1024
			 * calls jbd2_journal_dirty_data(), and we get right here.
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067
			 * It may be too late to journal the data.  Simply
			 * falling through to the next test will suffice: the
			 * data will be dirty and wil be checkpointed.  The
			 * ordering comments in the next comment block still
			 * apply.
			 */
			//J_ASSERT_JH(jh, jh->b_next_transaction == NULL);

			/*
			 * If we're journalling data, and this buffer was
			 * subject to a write(), it could be metadata, forget
			 * or shadow against the committing transaction.  Now,
			 * someone has dirtied the same darn page via a mapping
			 * and it is being writepage()'d.
			 * We *could* just steal the page from commit, with some
			 * fancy locking there.  Instead, we just skip it -
			 * don't tie the page's buffers to the new transaction
			 * at all.
			 * Implication: if we crash before the writepage() data
			 * is written into the filesystem, recovery will replay
			 * the write() data.
			 */
			if (jh->b_jlist != BJ_None &&
					jh->b_jlist != BJ_SyncData &&
					jh->b_jlist != BJ_Locked) {
				JBUFFER_TRACE(jh, "Not stealing");
				goto no_journal;
			}

			/*
			 * This buffer may be undergoing writeout in commit.  We
			 * can't return from here and let the caller dirty it
			 * again because that can cause the write-out loop in
			 * commit to never terminate.
			 */
			if (buffer_dirty(bh)) {
				get_bh(bh);
				spin_unlock(&journal->j_list_lock);
				jbd_unlock_bh_state(bh);
				need_brelse = 1;
				sync_dirty_buffer(bh);
				jbd_lock_bh_state(bh);
				spin_lock(&journal->j_list_lock);
1068 1069 1070 1071 1072
				/* Since we dropped the lock... */
				if (!buffer_mapped(bh)) {
					JBUFFER_TRACE(jh, "buffer got unmapped");
					goto no_journal;
				}
1073 1074 1075 1076 1077 1078 1079
				/* The buffer may become locked again at any
				   time if it is redirtied */
			}

			/* journal_clean_data_list() may have got there first */
			if (jh->b_transaction != NULL) {
				JBUFFER_TRACE(jh, "unfile from commit");
1080
				__jbd2_journal_temp_unlink_buffer(jh);
1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098
				/* It still points to the committing
				 * transaction; move it to this one so
				 * that the refile assert checks are
				 * happy. */
				jh->b_transaction = handle->h_transaction;
			}
			/* The buffer will be refiled below */

		}
		/*
		 * Special case --- the buffer might actually have been
		 * allocated and then immediately deallocated in the previous,
		 * committing transaction, so might still be left on that
		 * transaction's metadata lists.
		 */
		if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
			JBUFFER_TRACE(jh, "not on correct data list: unfile");
			J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1099
			__jbd2_journal_temp_unlink_buffer(jh);
1100 1101
			jh->b_transaction = handle->h_transaction;
			JBUFFER_TRACE(jh, "file as data");
1102
			__jbd2_journal_file_buffer(jh, handle->h_transaction,
1103 1104 1105 1106
						BJ_SyncData);
		}
	} else {
		JBUFFER_TRACE(jh, "not on a transaction");
1107
		__jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1108 1109 1110 1111 1112 1113 1114 1115 1116
	}
no_journal:
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(bh);
	if (need_brelse) {
		BUFFER_TRACE(bh, "brelse");
		__brelse(bh);
	}
	JBUFFER_TRACE(jh, "exit");
1117
	jbd2_journal_put_journal_head(jh);
1118 1119 1120 1121
	return 0;
}

/**
1122
 * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139
 * @handle: transaction to add buffer to.
 * @bh: buffer to mark
 *
 * mark dirty metadata which needs to be journaled as part of the current
 * transaction.
 *
 * The buffer is placed on the transaction's metadata list and is marked
 * as belonging to the transaction.
 *
 * Returns error number or 0 on success.
 *
 * Special care needs to be taken if the buffer already belongs to the
 * current committing transaction (in which case we should have frozen
 * data present for that commit).  In that case, we don't relink the
 * buffer: that only gets done when the old transaction finally
 * completes its commit.
 */
1140
int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	struct journal_head *jh = bh2jh(bh);

	jbd_debug(5, "journal_head %p\n", jh);
	JBUFFER_TRACE(jh, "entry");
	if (is_handle_aborted(handle))
		goto out;

	jbd_lock_bh_state(bh);

	if (jh->b_modified == 0) {
		/*
		 * This buffer's got modified and becoming part
		 * of the transaction. This needs to be done
		 * once a transaction -bzzz
		 */
		jh->b_modified = 1;
		J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
		handle->h_buffer_credits--;
	}

	/*
	 * fastpath, to avoid expensive locking.  If this buffer is already
	 * on the running transaction's metadata list there is nothing to do.
	 * Nobody can take it off again because there is a handle open.
	 * I _think_ we're OK here with SMP barriers - a mistaken decision will
	 * result in this test being false, so we go in and take the locks.
	 */
	if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
		JBUFFER_TRACE(jh, "fastpath");
		J_ASSERT_JH(jh, jh->b_transaction ==
					journal->j_running_transaction);
		goto out_unlock_bh;
	}

	set_buffer_jbddirty(bh);

	/*
	 * Metadata already on the current transaction list doesn't
	 * need to be filed.  Metadata on another transaction's list must
	 * be committing, and will be refiled once the commit completes:
	 * leave it alone for now.
	 */
	if (jh->b_transaction != transaction) {
		JBUFFER_TRACE(jh, "already on other transaction");
		J_ASSERT_JH(jh, jh->b_transaction ==
					journal->j_committing_transaction);
		J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
		/* And this case is illegal: we can't reuse another
		 * transaction's data buffer, ever. */
		goto out_unlock_bh;
	}

	/* That test should have eliminated the following case: */
1197
	J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1198 1199 1200

	JBUFFER_TRACE(jh, "file as BJ_Metadata");
	spin_lock(&journal->j_list_lock);
1201
	__jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1202 1203 1204 1205 1206 1207 1208 1209 1210
	spin_unlock(&journal->j_list_lock);
out_unlock_bh:
	jbd_unlock_bh_state(bh);
out:
	JBUFFER_TRACE(jh, "exit");
	return 0;
}

/*
1211
 * jbd2_journal_release_buffer: undo a get_write_access without any buffer
1212 1213 1214 1215
 * updates, if the update decided in the end that it didn't need access.
 *
 */
void
1216
jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1217 1218 1219 1220 1221
{
	BUFFER_TRACE(bh, "entry");
}

/**
1222
 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237
 * @handle: transaction handle
 * @bh:     bh to 'forget'
 *
 * We can only do the bforget if there are no commits pending against the
 * buffer.  If the buffer is dirty in the current running transaction we
 * can safely unlink it.
 *
 * bh may not be a journalled buffer at all - it may be a non-JBD
 * buffer which came off the hashtable.  Check for this.
 *
 * Decrements bh->b_count by one.
 *
 * Allow this call even if the handle has aborted --- it may be part of
 * the caller's cleanup after an abort.
 */
1238
int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1239 1240 1241 1242 1243 1244
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	struct journal_head *jh;
	int drop_reserve = 0;
	int err = 0;
1245
	int was_modified = 0;
1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263

	BUFFER_TRACE(bh, "entry");

	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);

	if (!buffer_jbd(bh))
		goto not_jbd;
	jh = bh2jh(bh);

	/* Critical error: attempting to delete a bitmap buffer, maybe?
	 * Don't do any jbd operations, and return an error. */
	if (!J_EXPECT_JH(jh, !jh->b_committed_data,
			 "inconsistent data on disk")) {
		err = -EIO;
		goto not_jbd;
	}

1264 1265 1266
	/* keep track of wether or not this transaction modified us */
	was_modified = jh->b_modified;

1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283
	/*
	 * The buffer's going from the transaction, we must drop
	 * all references -bzzz
	 */
	jh->b_modified = 0;

	if (jh->b_transaction == handle->h_transaction) {
		J_ASSERT_JH(jh, !jh->b_frozen_data);

		/* If we are forgetting a buffer which is already part
		 * of this transaction, then we can just drop it from
		 * the transaction immediately. */
		clear_buffer_dirty(bh);
		clear_buffer_jbddirty(bh);

		JBUFFER_TRACE(jh, "belongs to current transaction: unfile");

1284 1285 1286 1287 1288 1289
		/*
		 * we only want to drop a reference if this transaction
		 * modified the buffer
		 */
		if (was_modified)
			drop_reserve = 1;
1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303

		/*
		 * We are no longer going to journal this buffer.
		 * However, the commit of this transaction is still
		 * important to the buffer: the delete that we are now
		 * processing might obsolete an old log entry, so by
		 * committing, we can satisfy the buffer's checkpoint.
		 *
		 * So, if we have a checkpoint on the buffer, we should
		 * now refile the buffer on our BJ_Forget list so that
		 * we know to remove the checkpoint after we commit.
		 */

		if (jh->b_cp_transaction) {
1304 1305
			__jbd2_journal_temp_unlink_buffer(jh);
			__jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1306
		} else {
1307 1308
			__jbd2_journal_unfile_buffer(jh);
			jbd2_journal_remove_journal_head(bh);
1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328
			__brelse(bh);
			if (!buffer_jbd(bh)) {
				spin_unlock(&journal->j_list_lock);
				jbd_unlock_bh_state(bh);
				__bforget(bh);
				goto drop;
			}
		}
	} else if (jh->b_transaction) {
		J_ASSERT_JH(jh, (jh->b_transaction ==
				 journal->j_committing_transaction));
		/* However, if the buffer is still owned by a prior
		 * (committing) transaction, we can't drop it yet... */
		JBUFFER_TRACE(jh, "belongs to older transaction");
		/* ... but we CAN drop it from the new transaction if we
		 * have also modified it since the original commit. */

		if (jh->b_next_transaction) {
			J_ASSERT(jh->b_next_transaction == transaction);
			jh->b_next_transaction = NULL;
1329 1330 1331 1332 1333 1334 1335

			/*
			 * only drop a reference if this transaction modified
			 * the buffer
			 */
			if (was_modified)
				drop_reserve = 1;
1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351
		}
	}

not_jbd:
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(bh);
	__brelse(bh);
drop:
	if (drop_reserve) {
		/* no need to reserve log space for this block -bzzz */
		handle->h_buffer_credits++;
	}
	return err;
}

/**
1352
 * int jbd2_journal_stop() - complete a transaction
1353 1354 1355 1356 1357 1358 1359 1360 1361
 * @handle: tranaction to complete.
 *
 * All done for a particular handle.
 *
 * There is not much action needed here.  We just return any remaining
 * buffer credits to the transaction and remove the handle.  The only
 * complication is that we need to start a commit operation if the
 * filesystem is marked for synchronous update.
 *
1362
 * jbd2_journal_stop itself will not usually return an error, but it may
1363
 * do so in unusual circumstances.  In particular, expect it to
1364
 * return -EIO if a jbd2_journal_abort has been executed since the
1365 1366
 * transaction began.
 */
1367
int jbd2_journal_stop(handle_t *handle)
1368 1369 1370 1371 1372 1373 1374 1375 1376 1377
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	int old_handle_count, err;
	pid_t pid;

	J_ASSERT(journal_current_handle() == handle);

	if (is_handle_aborted(handle))
		err = -EIO;
1378 1379
	else {
		J_ASSERT(transaction->t_updates > 0);
1380
		err = 0;
1381
	}
1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443

	if (--handle->h_ref > 0) {
		jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
			  handle->h_ref);
		return err;
	}

	jbd_debug(4, "Handle %p going down\n", handle);

	/*
	 * Implement synchronous transaction batching.  If the handle
	 * was synchronous, don't force a commit immediately.  Let's
	 * yield and let another thread piggyback onto this transaction.
	 * Keep doing that while new threads continue to arrive.
	 * It doesn't cost much - we're about to run a commit and sleep
	 * on IO anyway.  Speeds up many-threaded, many-dir operations
	 * by 30x or more...
	 *
	 * But don't do this if this process was the most recent one to
	 * perform a synchronous write.  We do this to detect the case where a
	 * single process is doing a stream of sync writes.  No point in waiting
	 * for joiners in that case.
	 */
	pid = current->pid;
	if (handle->h_sync && journal->j_last_sync_writer != pid) {
		journal->j_last_sync_writer = pid;
		do {
			old_handle_count = transaction->t_handle_count;
			schedule_timeout_uninterruptible(1);
		} while (old_handle_count != transaction->t_handle_count);
	}

	current->journal_info = NULL;
	spin_lock(&journal->j_state_lock);
	spin_lock(&transaction->t_handle_lock);
	transaction->t_outstanding_credits -= handle->h_buffer_credits;
	transaction->t_updates--;
	if (!transaction->t_updates) {
		wake_up(&journal->j_wait_updates);
		if (journal->j_barrier_count)
			wake_up(&journal->j_wait_transaction_locked);
	}

	/*
	 * If the handle is marked SYNC, we need to set another commit
	 * going!  We also want to force a commit if the current
	 * transaction is occupying too much of the log, or if the
	 * transaction is too old now.
	 */
	if (handle->h_sync ||
			transaction->t_outstanding_credits >
				journal->j_max_transaction_buffers ||
			time_after_eq(jiffies, transaction->t_expires)) {
		/* Do this even for aborted journals: an abort still
		 * completes the commit thread, it just doesn't write
		 * anything to disk. */
		tid_t tid = transaction->t_tid;

		spin_unlock(&transaction->t_handle_lock);
		jbd_debug(2, "transaction too old, requesting commit for "
					"handle %p\n", handle);
		/* This is non-blocking */
1444
		__jbd2_log_start_commit(journal, transaction->t_tid);
1445 1446 1447
		spin_unlock(&journal->j_state_lock);

		/*
1448
		 * Special case: JBD2_SYNC synchronous updates require us
1449 1450 1451
		 * to wait for the commit to complete.
		 */
		if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1452
			err = jbd2_log_wait_commit(journal, tid);
1453 1454 1455 1456 1457
	} else {
		spin_unlock(&transaction->t_handle_lock);
		spin_unlock(&journal->j_state_lock);
	}

M
Mingming Cao 已提交
1458 1459
	lock_release(&handle->h_lockdep_map, 1, _THIS_IP_);

M
Mingming Cao 已提交
1460
	jbd2_free_handle(handle);
1461 1462 1463
	return err;
}

R
Randy Dunlap 已提交
1464 1465
/**
 * int jbd2_journal_force_commit() - force any uncommitted transactions
1466 1467 1468 1469 1470 1471
 * @journal: journal to force
 *
 * For synchronous operations: force any uncommitted transactions
 * to disk.  May seem kludgy, but it reuses all the handle batching
 * code in a very simple manner.
 */
1472
int jbd2_journal_force_commit(journal_t *journal)
1473 1474 1475 1476
{
	handle_t *handle;
	int ret;

1477
	handle = jbd2_journal_start(journal, 1);
1478 1479 1480 1481
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
	} else {
		handle->h_sync = 1;
1482
		ret = jbd2_journal_stop(handle);
1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549
	}
	return ret;
}

/*
 *
 * List management code snippets: various functions for manipulating the
 * transaction buffer lists.
 *
 */

/*
 * Append a buffer to a transaction list, given the transaction's list head
 * pointer.
 *
 * j_list_lock is held.
 *
 * jbd_lock_bh_state(jh2bh(jh)) is held.
 */

static inline void
__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
{
	if (!*list) {
		jh->b_tnext = jh->b_tprev = jh;
		*list = jh;
	} else {
		/* Insert at the tail of the list to preserve order */
		struct journal_head *first = *list, *last = first->b_tprev;
		jh->b_tprev = last;
		jh->b_tnext = first;
		last->b_tnext = first->b_tprev = jh;
	}
}

/*
 * Remove a buffer from a transaction list, given the transaction's list
 * head pointer.
 *
 * Called with j_list_lock held, and the journal may not be locked.
 *
 * jbd_lock_bh_state(jh2bh(jh)) is held.
 */

static inline void
__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
{
	if (*list == jh) {
		*list = jh->b_tnext;
		if (*list == jh)
			*list = NULL;
	}
	jh->b_tprev->b_tnext = jh->b_tnext;
	jh->b_tnext->b_tprev = jh->b_tprev;
}

/*
 * Remove a buffer from the appropriate transaction list.
 *
 * Note that this function can *change* the value of
 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list.  If the caller
 * is holding onto a copy of one of thee pointers, it could go bad.
 * Generally the caller needs to re-read the pointer from the transaction_t.
 *
 * Called under j_list_lock.  The journal may not be locked.
 */
1550
void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562
{
	struct journal_head **list = NULL;
	transaction_t *transaction;
	struct buffer_head *bh = jh2bh(jh);

	J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
	transaction = jh->b_transaction;
	if (transaction)
		assert_spin_locked(&transaction->t_journal->j_list_lock);

	J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
	if (jh->b_jlist != BJ_None)
1563
		J_ASSERT_JH(jh, transaction != NULL);
1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601

	switch (jh->b_jlist) {
	case BJ_None:
		return;
	case BJ_SyncData:
		list = &transaction->t_sync_datalist;
		break;
	case BJ_Metadata:
		transaction->t_nr_buffers--;
		J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
		list = &transaction->t_buffers;
		break;
	case BJ_Forget:
		list = &transaction->t_forget;
		break;
	case BJ_IO:
		list = &transaction->t_iobuf_list;
		break;
	case BJ_Shadow:
		list = &transaction->t_shadow_list;
		break;
	case BJ_LogCtl:
		list = &transaction->t_log_list;
		break;
	case BJ_Reserved:
		list = &transaction->t_reserved_list;
		break;
	case BJ_Locked:
		list = &transaction->t_locked_list;
		break;
	}

	__blist_del_buffer(list, jh);
	jh->b_jlist = BJ_None;
	if (test_clear_buffer_jbddirty(bh))
		mark_buffer_dirty(bh);	/* Expose it to the VM */
}

1602
void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1603
{
1604
	__jbd2_journal_temp_unlink_buffer(jh);
1605 1606 1607
	jh->b_transaction = NULL;
}

1608
void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1609 1610 1611
{
	jbd_lock_bh_state(jh2bh(jh));
	spin_lock(&journal->j_list_lock);
1612
	__jbd2_journal_unfile_buffer(jh);
1613 1614 1615 1616 1617
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(jh2bh(jh));
}

/*
1618
 * Called from jbd2_journal_try_to_free_buffers().
1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631
 *
 * Called under jbd_lock_bh_state(bh)
 */
static void
__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
{
	struct journal_head *jh;

	jh = bh2jh(bh);

	if (buffer_locked(bh) || buffer_dirty(bh))
		goto out;

1632
	if (jh->b_next_transaction != NULL)
1633 1634 1635
		goto out;

	spin_lock(&journal->j_list_lock);
1636
	if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
1637 1638 1639
		if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
			/* A written-back ordered data buffer */
			JBUFFER_TRACE(jh, "release data");
1640 1641
			__jbd2_journal_unfile_buffer(jh);
			jbd2_journal_remove_journal_head(bh);
1642 1643
			__brelse(bh);
		}
1644
	} else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1645 1646 1647
		/* written-back checkpointed metadata buffer */
		if (jh->b_jlist == BJ_None) {
			JBUFFER_TRACE(jh, "remove from checkpoint list");
1648 1649
			__jbd2_journal_remove_checkpoint(jh);
			jbd2_journal_remove_journal_head(bh);
1650 1651 1652 1653 1654 1655 1656 1657
			__brelse(bh);
		}
	}
	spin_unlock(&journal->j_list_lock);
out:
	return;
}

1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686
/*
 * jbd2_journal_try_to_free_buffers() could race with
 * jbd2_journal_commit_transaction(). The later might still hold the
 * reference count to the buffers when inspecting them on
 * t_syncdata_list or t_locked_list.
 *
 * jbd2_journal_try_to_free_buffers() will call this function to
 * wait for the current transaction to finish syncing data buffers, before
 * try to free that buffer.
 *
 * Called with journal->j_state_lock hold.
 */
static void jbd2_journal_wait_for_transaction_sync_data(journal_t *journal)
{
	transaction_t *transaction;
	tid_t tid;

	spin_lock(&journal->j_state_lock);
	transaction = journal->j_committing_transaction;

	if (!transaction) {
		spin_unlock(&journal->j_state_lock);
		return;
	}

	tid = transaction->t_tid;
	spin_unlock(&journal->j_state_lock);
	jbd2_log_wait_commit(journal, tid);
}
1687 1688

/**
1689
 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1690 1691
 * @journal: journal for operation
 * @page: to try and free
1692 1693 1694
 * @gfp_mask: we use the mask to detect how hard should we try to release
 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
 * release the buffers.
1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707
 *
 *
 * For all the buffers on this page,
 * if they are fully written out ordered data, move them onto BUF_CLEAN
 * so try_to_free_buffers() can reap them.
 *
 * This function returns non-zero if we wish try_to_free_buffers()
 * to be called. We do this if the page is releasable by try_to_free_buffers().
 * We also do it if the page has locked or dirty buffers and the caller wants
 * us to perform sync or async writeout.
 *
 * This complicates JBD locking somewhat.  We aren't protected by the
 * BKL here.  We wish to remove the buffer from its committing or
1708
 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1709 1710 1711 1712
 *
 * This may *change* the value of transaction_t->t_datalist, so anyone
 * who looks at t_datalist needs to lock against this function.
 *
1713 1714
 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
 * buffer.  So we need to lock against that.  jbd2_journal_dirty_data()
1715 1716 1717 1718 1719 1720 1721 1722
 * will come out of the lock with the buffer dirty, which makes it
 * ineligible for release here.
 *
 * Who else is affected by this?  hmm...  Really the only contender
 * is do_get_write_access() - it could be looking at the buffer while
 * journal_try_to_free_buffer() is changing its state.  But that
 * cannot happen because we never reallocate freed data as metadata
 * while the data is part of a transaction.  Yes?
1723 1724
 *
 * Return 0 on failure, 1 on success
1725
 */
1726
int jbd2_journal_try_to_free_buffers(journal_t *journal,
1727
				struct page *page, gfp_t gfp_mask)
1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742
{
	struct buffer_head *head;
	struct buffer_head *bh;
	int ret = 0;

	J_ASSERT(PageLocked(page));

	head = page_buffers(page);
	bh = head;
	do {
		struct journal_head *jh;

		/*
		 * We take our own ref against the journal_head here to avoid
		 * having to add tons of locking around each instance of
1743 1744
		 * jbd2_journal_remove_journal_head() and
		 * jbd2_journal_put_journal_head().
1745
		 */
1746
		jh = jbd2_journal_grab_journal_head(bh);
1747 1748 1749 1750 1751
		if (!jh)
			continue;

		jbd_lock_bh_state(bh);
		__journal_try_to_free_buffer(journal, bh);
1752
		jbd2_journal_put_journal_head(jh);
1753 1754 1755 1756
		jbd_unlock_bh_state(bh);
		if (buffer_jbd(bh))
			goto busy;
	} while ((bh = bh->b_this_page) != head);
1757

1758
	ret = try_to_free_buffers(page);
1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778

	/*
	 * There are a number of places where jbd2_journal_try_to_free_buffers()
	 * could race with jbd2_journal_commit_transaction(), the later still
	 * holds the reference to the buffers to free while processing them.
	 * try_to_free_buffers() failed to free those buffers. Some of the
	 * caller of releasepage() request page buffers to be dropped, otherwise
	 * treat the fail-to-free as errors (such as generic_file_direct_IO())
	 *
	 * So, if the caller of try_to_release_page() wants the synchronous
	 * behaviour(i.e make sure buffers are dropped upon return),
	 * let's wait for the current transaction to finish flush of
	 * dirty data buffers, then try to free those buffers again,
	 * with the journal locked.
	 */
	if (ret == 0 && (gfp_mask & __GFP_WAIT) && (gfp_mask & __GFP_FS)) {
		jbd2_journal_wait_for_transaction_sync_data(journal);
		ret = try_to_free_buffers(page);
	}

1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799
busy:
	return ret;
}

/*
 * This buffer is no longer needed.  If it is on an older transaction's
 * checkpoint list we need to record it on this transaction's forget list
 * to pin this buffer (and hence its checkpointing transaction) down until
 * this transaction commits.  If the buffer isn't on a checkpoint list, we
 * release it.
 * Returns non-zero if JBD no longer has an interest in the buffer.
 *
 * Called under j_list_lock.
 *
 * Called under jbd_lock_bh_state(bh).
 */
static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
{
	int may_free = 1;
	struct buffer_head *bh = jh2bh(jh);

1800
	__jbd2_journal_unfile_buffer(jh);
1801 1802 1803

	if (jh->b_cp_transaction) {
		JBUFFER_TRACE(jh, "on running+cp transaction");
1804
		__jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1805 1806 1807 1808
		clear_buffer_jbddirty(bh);
		may_free = 0;
	} else {
		JBUFFER_TRACE(jh, "on running transaction");
1809
		jbd2_journal_remove_journal_head(bh);
1810 1811 1812 1813 1814 1815
		__brelse(bh);
	}
	return may_free;
}

/*
1816
 * jbd2_journal_invalidatepage
1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883
 *
 * This code is tricky.  It has a number of cases to deal with.
 *
 * There are two invariants which this code relies on:
 *
 * i_size must be updated on disk before we start calling invalidatepage on the
 * data.
 *
 *  This is done in ext3 by defining an ext3_setattr method which
 *  updates i_size before truncate gets going.  By maintaining this
 *  invariant, we can be sure that it is safe to throw away any buffers
 *  attached to the current transaction: once the transaction commits,
 *  we know that the data will not be needed.
 *
 *  Note however that we can *not* throw away data belonging to the
 *  previous, committing transaction!
 *
 * Any disk blocks which *are* part of the previous, committing
 * transaction (and which therefore cannot be discarded immediately) are
 * not going to be reused in the new running transaction
 *
 *  The bitmap committed_data images guarantee this: any block which is
 *  allocated in one transaction and removed in the next will be marked
 *  as in-use in the committed_data bitmap, so cannot be reused until
 *  the next transaction to delete the block commits.  This means that
 *  leaving committing buffers dirty is quite safe: the disk blocks
 *  cannot be reallocated to a different file and so buffer aliasing is
 *  not possible.
 *
 *
 * The above applies mainly to ordered data mode.  In writeback mode we
 * don't make guarantees about the order in which data hits disk --- in
 * particular we don't guarantee that new dirty data is flushed before
 * transaction commit --- so it is always safe just to discard data
 * immediately in that mode.  --sct
 */

/*
 * The journal_unmap_buffer helper function returns zero if the buffer
 * concerned remains pinned as an anonymous buffer belonging to an older
 * transaction.
 *
 * We're outside-transaction here.  Either or both of j_running_transaction
 * and j_committing_transaction may be NULL.
 */
static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
{
	transaction_t *transaction;
	struct journal_head *jh;
	int may_free = 1;
	int ret;

	BUFFER_TRACE(bh, "entry");

	/*
	 * It is safe to proceed here without the j_list_lock because the
	 * buffers cannot be stolen by try_to_free_buffers as long as we are
	 * holding the page lock. --sct
	 */

	if (!buffer_jbd(bh))
		goto zap_buffer_unlocked;

	spin_lock(&journal->j_state_lock);
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);

1884
	jh = jbd2_journal_grab_journal_head(bh);
1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914
	if (!jh)
		goto zap_buffer_no_jh;

	transaction = jh->b_transaction;
	if (transaction == NULL) {
		/* First case: not on any transaction.  If it
		 * has no checkpoint link, then we can zap it:
		 * it's a writeback-mode buffer so we don't care
		 * if it hits disk safely. */
		if (!jh->b_cp_transaction) {
			JBUFFER_TRACE(jh, "not on any transaction: zap");
			goto zap_buffer;
		}

		if (!buffer_dirty(bh)) {
			/* bdflush has written it.  We can drop it now */
			goto zap_buffer;
		}

		/* OK, it must be in the journal but still not
		 * written fully to disk: it's metadata or
		 * journaled data... */

		if (journal->j_running_transaction) {
			/* ... and once the current transaction has
			 * committed, the buffer won't be needed any
			 * longer. */
			JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
			ret = __dispose_buffer(jh,
					journal->j_running_transaction);
1915
			jbd2_journal_put_journal_head(jh);
1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928
			spin_unlock(&journal->j_list_lock);
			jbd_unlock_bh_state(bh);
			spin_unlock(&journal->j_state_lock);
			return ret;
		} else {
			/* There is no currently-running transaction. So the
			 * orphan record which we wrote for this file must have
			 * passed into commit.  We must attach this buffer to
			 * the committing transaction, if it exists. */
			if (journal->j_committing_transaction) {
				JBUFFER_TRACE(jh, "give to committing trans");
				ret = __dispose_buffer(jh,
					journal->j_committing_transaction);
1929
				jbd2_journal_put_journal_head(jh);
1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941
				spin_unlock(&journal->j_list_lock);
				jbd_unlock_bh_state(bh);
				spin_unlock(&journal->j_state_lock);
				return ret;
			} else {
				/* The orphan record's transaction has
				 * committed.  We can cleanse this buffer */
				clear_buffer_jbddirty(bh);
				goto zap_buffer;
			}
		}
	} else if (transaction == journal->j_committing_transaction) {
1942
		JBUFFER_TRACE(jh, "on committing transaction");
1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962
		if (jh->b_jlist == BJ_Locked) {
			/*
			 * The buffer is on the committing transaction's locked
			 * list.  We have the buffer locked, so I/O has
			 * completed.  So we can nail the buffer now.
			 */
			may_free = __dispose_buffer(jh, transaction);
			goto zap_buffer;
		}
		/*
		 * If it is committing, we simply cannot touch it.  We
		 * can remove it's next_transaction pointer from the
		 * running transaction if that is set, but nothing
		 * else. */
		set_buffer_freed(bh);
		if (jh->b_next_transaction) {
			J_ASSERT(jh->b_next_transaction ==
					journal->j_running_transaction);
			jh->b_next_transaction = NULL;
		}
1963
		jbd2_journal_put_journal_head(jh);
1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975
		spin_unlock(&journal->j_list_lock);
		jbd_unlock_bh_state(bh);
		spin_unlock(&journal->j_state_lock);
		return 0;
	} else {
		/* Good, the buffer belongs to the running transaction.
		 * We are writing our own transaction's data, not any
		 * previous one's, so it is safe to throw it away
		 * (remember that we expect the filesystem to have set
		 * i_size already for this truncate so recovery will not
		 * expose the disk blocks we are discarding here.) */
		J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1976
		JBUFFER_TRACE(jh, "on running transaction");
1977 1978 1979 1980
		may_free = __dispose_buffer(jh, transaction);
	}

zap_buffer:
1981
	jbd2_journal_put_journal_head(jh);
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996
zap_buffer_no_jh:
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(bh);
	spin_unlock(&journal->j_state_lock);
zap_buffer_unlocked:
	clear_buffer_dirty(bh);
	J_ASSERT_BH(bh, !buffer_jbddirty(bh));
	clear_buffer_mapped(bh);
	clear_buffer_req(bh);
	clear_buffer_new(bh);
	bh->b_bdev = NULL;
	return may_free;
}

/**
1997
 * void jbd2_journal_invalidatepage()
1998 1999 2000 2001 2002 2003 2004
 * @journal: journal to use for flush...
 * @page:    page to flush
 * @offset:  length of page to invalidate.
 *
 * Reap page buffers containing data after offset in page.
 *
 */
2005
void jbd2_journal_invalidatepage(journal_t *journal,
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046
		      struct page *page,
		      unsigned long offset)
{
	struct buffer_head *head, *bh, *next;
	unsigned int curr_off = 0;
	int may_free = 1;

	if (!PageLocked(page))
		BUG();
	if (!page_has_buffers(page))
		return;

	/* We will potentially be playing with lists other than just the
	 * data lists (especially for journaled data mode), so be
	 * cautious in our locking. */

	head = bh = page_buffers(page);
	do {
		unsigned int next_off = curr_off + bh->b_size;
		next = bh->b_this_page;

		if (offset <= curr_off) {
			/* This block is wholly outside the truncation point */
			lock_buffer(bh);
			may_free &= journal_unmap_buffer(journal, bh);
			unlock_buffer(bh);
		}
		curr_off = next_off;
		bh = next;

	} while (bh != head);

	if (!offset) {
		if (may_free && try_to_free_buffers(page))
			J_ASSERT(!page_has_buffers(page));
	}
}

/*
 * File a buffer on the given transaction list.
 */
2047
void __jbd2_journal_file_buffer(struct journal_head *jh,
2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058
			transaction_t *transaction, int jlist)
{
	struct journal_head **list = NULL;
	int was_dirty = 0;
	struct buffer_head *bh = jh2bh(jh);

	J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
	assert_spin_locked(&transaction->t_journal->j_list_lock);

	J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
	J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2059
				jh->b_transaction == NULL);
2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075

	if (jh->b_transaction && jh->b_jlist == jlist)
		return;

	/* The following list of buffer states needs to be consistent
	 * with __jbd_unexpected_dirty_buffer()'s handling of dirty
	 * state. */

	if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
	    jlist == BJ_Shadow || jlist == BJ_Forget) {
		if (test_clear_buffer_dirty(bh) ||
		    test_clear_buffer_jbddirty(bh))
			was_dirty = 1;
	}

	if (jh->b_transaction)
2076
		__jbd2_journal_temp_unlink_buffer(jh);
2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117
	jh->b_transaction = transaction;

	switch (jlist) {
	case BJ_None:
		J_ASSERT_JH(jh, !jh->b_committed_data);
		J_ASSERT_JH(jh, !jh->b_frozen_data);
		return;
	case BJ_SyncData:
		list = &transaction->t_sync_datalist;
		break;
	case BJ_Metadata:
		transaction->t_nr_buffers++;
		list = &transaction->t_buffers;
		break;
	case BJ_Forget:
		list = &transaction->t_forget;
		break;
	case BJ_IO:
		list = &transaction->t_iobuf_list;
		break;
	case BJ_Shadow:
		list = &transaction->t_shadow_list;
		break;
	case BJ_LogCtl:
		list = &transaction->t_log_list;
		break;
	case BJ_Reserved:
		list = &transaction->t_reserved_list;
		break;
	case BJ_Locked:
		list =  &transaction->t_locked_list;
		break;
	}

	__blist_add_buffer(list, jh);
	jh->b_jlist = jlist;

	if (was_dirty)
		set_buffer_jbddirty(bh);
}

2118
void jbd2_journal_file_buffer(struct journal_head *jh,
2119 2120 2121 2122
				transaction_t *transaction, int jlist)
{
	jbd_lock_bh_state(jh2bh(jh));
	spin_lock(&transaction->t_journal->j_list_lock);
2123
	__jbd2_journal_file_buffer(jh, transaction, jlist);
2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137
	spin_unlock(&transaction->t_journal->j_list_lock);
	jbd_unlock_bh_state(jh2bh(jh));
}

/*
 * Remove a buffer from its current buffer list in preparation for
 * dropping it from its current transaction entirely.  If the buffer has
 * already started to be used by a subsequent transaction, refile the
 * buffer on that transaction's metadata list.
 *
 * Called under journal->j_list_lock
 *
 * Called under jbd_lock_bh_state(jh2bh(jh))
 */
2138
void __jbd2_journal_refile_buffer(struct journal_head *jh)
2139 2140 2141 2142 2143 2144 2145 2146 2147 2148
{
	int was_dirty;
	struct buffer_head *bh = jh2bh(jh);

	J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
	if (jh->b_transaction)
		assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);

	/* If the buffer is now unused, just drop it. */
	if (jh->b_next_transaction == NULL) {
2149
		__jbd2_journal_unfile_buffer(jh);
2150 2151 2152 2153 2154 2155 2156 2157 2158
		return;
	}

	/*
	 * It has been modified by a later transaction: add it to the new
	 * transaction's metadata list.
	 */

	was_dirty = test_clear_buffer_jbddirty(bh);
2159
	__jbd2_journal_temp_unlink_buffer(jh);
2160 2161
	jh->b_transaction = jh->b_next_transaction;
	jh->b_next_transaction = NULL;
2162
	__jbd2_journal_file_buffer(jh, jh->b_transaction,
2163
				jh->b_modified ? BJ_Metadata : BJ_Reserved);
2164 2165 2166 2167 2168 2169 2170 2171 2172 2173
	J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);

	if (was_dirty)
		set_buffer_jbddirty(bh);
}

/*
 * For the unlocked version of this call, also make sure that any
 * hanging journal_head is cleaned up if necessary.
 *
2174
 * __jbd2_journal_refile_buffer is usually called as part of a single locked
2175 2176 2177
 * operation on a buffer_head, in which the caller is probably going to
 * be hooking the journal_head onto other lists.  In that case it is up
 * to the caller to remove the journal_head if necessary.  For the
2178
 * unlocked jbd2_journal_refile_buffer call, the caller isn't going to be
2179 2180 2181 2182 2183
 * doing anything else to the buffer so we need to do the cleanup
 * ourselves to avoid a jh leak.
 *
 * *** The journal_head may be freed by this call! ***
 */
2184
void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2185 2186 2187 2188 2189 2190
{
	struct buffer_head *bh = jh2bh(jh);

	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);

2191
	__jbd2_journal_refile_buffer(jh);
2192
	jbd_unlock_bh_state(bh);
2193
	jbd2_journal_remove_journal_head(bh);
2194 2195 2196 2197

	spin_unlock(&journal->j_list_lock);
	__brelse(bh);
}