transaction.c 69.7 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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#include <linux/hrtimer.h>
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#include <linux/backing-dev.h>
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#include <linux/bug.h>
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#include <linux/module.h>
32

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static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
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static void __jbd2_journal_unfile_buffer(struct journal_head *jh);
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static struct kmem_cache *transaction_cache;
int __init jbd2_journal_init_transaction_cache(void)
{
	J_ASSERT(!transaction_cache);
	transaction_cache = kmem_cache_create("jbd2_transaction_s",
					sizeof(transaction_t),
					0,
					SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY,
					NULL);
	if (transaction_cache)
		return 0;
	return -ENOMEM;
}

void jbd2_journal_destroy_transaction_cache(void)
{
	if (transaction_cache) {
		kmem_cache_destroy(transaction_cache);
		transaction_cache = NULL;
	}
}

void jbd2_journal_free_transaction(transaction_t *transaction)
{
	if (unlikely(ZERO_OR_NULL_PTR(transaction)))
		return;
	kmem_cache_free(transaction_cache, transaction);
}

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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;
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	transaction->t_start_time = ktime_get();
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	transaction->t_tid = journal->j_transaction_sequence++;
	transaction->t_expires = jiffies + journal->j_commit_interval;
	spin_lock_init(&transaction->t_handle_lock);
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	atomic_set(&transaction->t_updates, 0);
	atomic_set(&transaction->t_outstanding_credits, 0);
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	atomic_set(&transaction->t_handle_count, 0);
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	INIT_LIST_HEAD(&transaction->t_inode_list);
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	INIT_LIST_HEAD(&transaction->t_private_list);
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	/* Set up the commit timer for the new transaction. */
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	journal->j_commit_timer.expires = round_jiffies_up(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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	transaction->t_requested = 0;
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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.
 */

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/*
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 * Update transaction's maximum wait time, if debugging is enabled.
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 *
 * In order for t_max_wait to be reliable, it must be protected by a
 * lock.  But doing so will mean that start_this_handle() can not be
 * run in parallel on SMP systems, which limits our scalability.  So
 * unless debugging is enabled, we no longer update t_max_wait, which
 * means that maximum wait time reported by the jbd2_run_stats
 * tracepoint will always be zero.
 */
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static inline void update_t_max_wait(transaction_t *transaction,
				     unsigned long ts)
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{
#ifdef CONFIG_JBD2_DEBUG
	if (jbd2_journal_enable_debug &&
	    time_after(transaction->t_start, ts)) {
		ts = jbd2_time_diff(ts, transaction->t_start);
		spin_lock(&transaction->t_handle_lock);
		if (ts > transaction->t_max_wait)
			transaction->t_max_wait = ts;
		spin_unlock(&transaction->t_handle_lock);
	}
#endif
}

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/*
 * 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.
 */

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static int start_this_handle(journal_t *journal, handle_t *handle,
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			     gfp_t gfp_mask)
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{
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	transaction_t	*transaction, *new_transaction = NULL;
	tid_t		tid;
	int		needed, need_to_start;
	int		nblocks = handle->h_buffer_credits;
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	unsigned long ts = jiffies;
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	if (nblocks > journal->j_max_transaction_buffers) {
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		printk(KERN_ERR "JBD2: %s wants too many credits (%d > %d)\n",
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		       current->comm, nblocks,
		       journal->j_max_transaction_buffers);
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		return -ENOSPC;
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	}

alloc_transaction:
	if (!journal->j_running_transaction) {
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		new_transaction = kmem_cache_zalloc(transaction_cache,
						    gfp_mask);
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		if (!new_transaction) {
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			/*
			 * If __GFP_FS is not present, then we may be
			 * being called from inside the fs writeback
			 * layer, so we MUST NOT fail.  Since
			 * __GFP_NOFAIL is going away, we will arrange
			 * to retry the allocation ourselves.
			 */
			if ((gfp_mask & __GFP_FS) == 0) {
				congestion_wait(BLK_RW_ASYNC, HZ/50);
				goto alloc_transaction;
			}
			return -ENOMEM;
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		}
	}

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

	/*
	 * We need to hold j_state_lock until t_updates has been incremented,
	 * for proper journal barrier handling
	 */
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repeat:
	read_lock(&journal->j_state_lock);
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	BUG_ON(journal->j_flags & JBD2_UNMOUNT);
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	if (is_journal_aborted(journal) ||
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	    (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
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		read_unlock(&journal->j_state_lock);
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		jbd2_journal_free_transaction(new_transaction);
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		return -EROFS;
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	}

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

	if (!journal->j_running_transaction) {
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		read_unlock(&journal->j_state_lock);
		if (!new_transaction)
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			goto alloc_transaction;
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		write_lock(&journal->j_state_lock);
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		if (!journal->j_running_transaction &&
		    !journal->j_barrier_count) {
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			jbd2_get_transaction(journal, new_transaction);
			new_transaction = NULL;
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		}
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		write_unlock(&journal->j_state_lock);
		goto repeat;
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	}

	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);
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		read_unlock(&journal->j_state_lock);
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		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.
	 */
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	needed = atomic_add_return(nblocks,
				   &transaction->t_outstanding_credits);
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	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);
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		atomic_sub(nblocks, &transaction->t_outstanding_credits);
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		prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
				TASK_UNINTERRUPTIBLE);
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		tid = transaction->t_tid;
		need_to_start = !tid_geq(journal->j_commit_request, tid);
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		read_unlock(&journal->j_state_lock);
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		if (need_to_start)
			jbd2_log_start_commit(journal, tid);
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		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.
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	 * Also, this test is inconsistent with the matching one in
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	 * jbd2_journal_extend().
293
	 */
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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);
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		atomic_sub(nblocks, &transaction->t_outstanding_credits);
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		read_unlock(&journal->j_state_lock);
		write_lock(&journal->j_state_lock);
		if (__jbd2_log_space_left(journal) < jbd_space_needed(journal))
			__jbd2_log_wait_for_space(journal);
		write_unlock(&journal->j_state_lock);
		goto repeat;
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	}

	/* OK, account for the buffers that this operation expects to
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	 * use and add the handle to the running transaction. 
	 */
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	update_t_max_wait(transaction, ts);
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	handle->h_transaction = transaction;
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	atomic_inc(&transaction->t_updates);
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	atomic_inc(&transaction->t_handle_count);
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	jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
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		  handle, nblocks,
		  atomic_read(&transaction->t_outstanding_credits),
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		  __jbd2_log_space_left(journal));
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	read_unlock(&journal->j_state_lock);
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	lock_map_acquire(&handle->h_lockdep_map);
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	jbd2_journal_free_transaction(new_transaction);
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	return 0;
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}

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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.
 *
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 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
 * on failure.
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 */
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handle_t *jbd2__journal_start(journal_t *journal, int nblocks, gfp_t gfp_mask)
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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;

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	err = start_this_handle(journal, handle, gfp_mask);
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	if (err < 0) {
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		jbd2_free_handle(handle);
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		current->journal_info = NULL;
		handle = ERR_PTR(err);
	}
	return handle;
}
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EXPORT_SYMBOL(jbd2__journal_start);


handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
{
	return jbd2__journal_start(journal, nblocks, GFP_NOFS);
}
EXPORT_SYMBOL(jbd2_journal_start);

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/**
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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;

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	read_lock(&journal->j_state_lock);
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	/* 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);
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	wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks;
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	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;
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	atomic_add(nblocks, &transaction->t_outstanding_credits);
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	result = 0;

	jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
unlock:
	spin_unlock(&transaction->t_handle_lock);
error_out:
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	read_unlock(&journal->j_state_lock);
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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, gfp_t gfp_mask)
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{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
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	tid_t		tid;
	int		need_to_start, ret;
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	/* 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.
	 */
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	J_ASSERT(atomic_read(&transaction->t_updates) > 0);
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	J_ASSERT(journal_current_handle() == handle);

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	read_lock(&journal->j_state_lock);
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	spin_lock(&transaction->t_handle_lock);
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	atomic_sub(handle->h_buffer_credits,
		   &transaction->t_outstanding_credits);
	if (atomic_dec_and_test(&transaction->t_updates))
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		wake_up(&journal->j_wait_updates);
	spin_unlock(&transaction->t_handle_lock);

	jbd_debug(2, "restarting handle %p\n", handle);
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	tid = transaction->t_tid;
	need_to_start = !tid_geq(journal->j_commit_request, tid);
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	read_unlock(&journal->j_state_lock);
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	if (need_to_start)
		jbd2_log_start_commit(journal, tid);
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513
	lock_map_release(&handle->h_lockdep_map);
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	handle->h_buffer_credits = nblocks;
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	ret = start_this_handle(journal, handle, gfp_mask);
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	return ret;
}
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EXPORT_SYMBOL(jbd2__journal_restart);
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int jbd2_journal_restart(handle_t *handle, int nblocks)
{
	return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
}
EXPORT_SYMBOL(jbd2_journal_restart);

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/**
528
 * 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);

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	write_lock(&journal->j_state_lock);
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	++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);
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		prepare_to_wait(&journal->j_wait_updates, &wait,
				TASK_UNINTERRUPTIBLE);
554
		if (!atomic_read(&transaction->t_updates)) {
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			spin_unlock(&transaction->t_handle_lock);
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			finish_wait(&journal->j_wait_updates, &wait);
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			break;
		}
		spin_unlock(&transaction->t_handle_lock);
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		write_unlock(&journal->j_state_lock);
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		schedule();
		finish_wait(&journal->j_wait_updates, &wait);
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		write_lock(&journal->j_state_lock);
564
	}
565
	write_unlock(&journal->j_state_lock);
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	/*
	 * 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);
}

/**
577
 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
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 * @journal:  Journal to release the barrier on.
 *
580
 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
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 *
 * Should be called without the journal lock held.
 */
584
void jbd2_journal_unlock_updates (journal_t *journal)
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{
	J_ASSERT(journal->j_barrier_count != 0);

	mutex_unlock(&journal->j_barrier);
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	write_lock(&journal->j_state_lock);
590
	--journal->j_barrier_count;
591
	write_unlock(&journal->j_state_lock);
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	wake_up(&journal->j_wait_transaction_locked);
}

595
static void warn_dirty_buffer(struct buffer_head *bh)
596
{
597
	char b[BDEVNAME_SIZE];
598

599
	printk(KERN_WARNING
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	       "JBD2: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
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	       "There's a risk of filesystem corruption in case of system "
	       "crash.\n",
	       bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
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}

/*
 * 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;

633
	jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
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	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);
670
			warn_dirty_buffer(bh);
671 672 673 674 675 676
		}
		/*
		 * 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.
		 */
677 678 679
		JBUFFER_TRACE(jh, "Journalling dirty buffer");
		clear_buffer_dirty(bh);
		set_buffer_jbddirty(bh);
680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698
	}

	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;

699 700 701 702 703 704
	/*
	 * this is the first time this transaction is touching this buffer,
	 * reset the modified flag
	 */
       jh->b_modified = 0;

705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772
	/*
	 * 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
773
					jbd2_alloc(jh2bh(jh)->b_size,
774 775 776 777
							 GFP_NOFS);
				if (!frozen_buffer) {
					printk(KERN_EMERG
					       "%s: OOM for frozen_buffer\n",
778
					       __func__);
779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803
					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);
		JBUFFER_TRACE(jh, "file as BJ_Reserved");
		spin_lock(&journal->j_list_lock);
804
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
805 806 807 808 809 810 811 812 813 814 815 816
		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;
817
		offset = offset_in_page(jh2bh(jh)->b_data);
818
		source = kmap_atomic(page);
819 820 821
		/* Fire data frozen trigger just before we copy the data */
		jbd2_buffer_frozen_trigger(jh, source + offset,
					   jh->b_triggers);
822
		memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
823
		kunmap_atomic(source);
J
Joel Becker 已提交
824 825 826 827 828 829

		/*
		 * Now that the frozen data is saved off, we need to store
		 * any matching triggers.
		 */
		jh->b_frozen_triggers = jh->b_triggers;
830 831 832 833 834 835 836
	}
	jbd_unlock_bh_state(bh);

	/*
	 * If we are about to journal a buffer, then any revoke pending on it is
	 * no longer valid
	 */
837
	jbd2_journal_cancel_revoke(handle, jh);
838 839 840

out:
	if (unlikely(frozen_buffer))	/* It's usually NULL */
M
Mingming Cao 已提交
841
		jbd2_free(frozen_buffer, bh->b_size);
842 843 844 845 846 847

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

/**
848
 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
849 850 851 852 853 854 855 856 857
 * @handle: transaction to add buffer modifications to
 * @bh:     bh to be used for metadata writes
 *
 * 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.
 */

858
int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
859
{
860
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
861 862 863 864 865 866
	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);
867
	jbd2_journal_put_journal_head(jh);
868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884
	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. */

/**
885
 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
886 887 888 889 890
 * @handle: transaction to new buffer to
 * @bh: new buffer.
 *
 * Call this if you create a new bh.
 */
891
int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
892 893 894
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
895
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922
	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) {
923 924 925 926 927 928 929 930 931
		/*
		 * Previous jbd2_journal_forget() could have left the buffer
		 * with jbddirty bit set because it was being committed. When
		 * the commit finished, we've filed the buffer for
		 * checkpointing and marked it dirty. Now we are reallocating
		 * the buffer so the transaction freeing it must have
		 * committed and so it's safe to clear the dirty bit.
		 */
		clear_buffer_dirty(jh2bh(jh));
932 933 934
		/* first access by this transaction */
		jh->b_modified = 0;

935
		JBUFFER_TRACE(jh, "file as BJ_Reserved");
936
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
937
	} else if (jh->b_transaction == journal->j_committing_transaction) {
938 939 940
		/* first access by this transaction */
		jh->b_modified = 0;

941 942 943 944 945 946 947 948 949 950 951 952 953 954
		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");
955
	jbd2_journal_cancel_revoke(handle, jh);
956
out:
957
	jbd2_journal_put_journal_head(jh);
958 959 960 961
	return err;
}

/**
962
 * int jbd2_journal_get_undo_access() -  Notify intent to modify metadata with
963 964 965 966 967 968 969 970 971 972 973
 *     non-rewindable consequences
 * @handle: transaction
 * @bh: buffer to undo
 *
 * 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.
 *
974
 * To deal with that, jbd2_journal_get_undo_access requests write access to a
975 976 977 978 979 980 981 982 983 984 985 986
 * 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.
 */
987
int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
988 989
{
	int err;
990
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005
	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
1006
		committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
1007 1008
		if (!committed_data) {
			printk(KERN_EMERG "%s: No memory for committed data\n",
1009
				__func__);
1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030
			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:
1031
	jbd2_journal_put_journal_head(jh);
1032
	if (unlikely(committed_data))
M
Mingming Cao 已提交
1033
		jbd2_free(committed_data, bh->b_size);
1034 1035 1036
	return err;
}

J
Joel Becker 已提交
1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
/**
 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
 * @bh: buffer to trigger on
 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
 *
 * Set any triggers on this journal_head.  This is always safe, because
 * triggers for a committing buffer will be saved off, and triggers for
 * a running transaction will match the buffer in that transaction.
 *
 * Call with NULL to clear the triggers.
 */
void jbd2_journal_set_triggers(struct buffer_head *bh,
			       struct jbd2_buffer_trigger_type *type)
{
	struct journal_head *jh = bh2jh(bh);

	jh->b_triggers = type;
}

1056
void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
J
Joel Becker 已提交
1057 1058 1059 1060
				struct jbd2_buffer_trigger_type *triggers)
{
	struct buffer_head *bh = jh2bh(jh);

1061
	if (!triggers || !triggers->t_frozen)
J
Joel Becker 已提交
1062 1063
		return;

1064
	triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
J
Joel Becker 已提交
1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077
}

void jbd2_buffer_abort_trigger(struct journal_head *jh,
			       struct jbd2_buffer_trigger_type *triggers)
{
	if (!triggers || !triggers->t_abort)
		return;

	triggers->t_abort(triggers, jh2bh(jh));
}



1078
/**
1079
 * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
1080 1081 1082 1083 1084 1085
 * @handle: transaction to add buffer to.
 * @bh: buffer to mark
 *
 * mark dirty metadata which needs to be journaled as part of the current
 * transaction.
 *
1086 1087 1088 1089
 * The buffer must have previously had jbd2_journal_get_write_access()
 * called so that it has a valid journal_head attached to the buffer
 * head.
 *
1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
 * 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.
 */
1101
int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1102 1103 1104 1105
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	struct journal_head *jh = bh2jh(bh);
1106
	int ret = 0;
1107 1108 1109 1110 1111

	jbd_debug(5, "journal_head %p\n", jh);
	JBUFFER_TRACE(jh, "entry");
	if (is_handle_aborted(handle))
		goto out;
1112 1113 1114 1115
	if (!buffer_jbd(bh)) {
		ret = -EUCLEAN;
		goto out;
	}
1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138

	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");
1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152
		if (unlikely(jh->b_transaction !=
			     journal->j_running_transaction)) {
			printk(KERN_EMERG "JBD: %s: "
			       "jh->b_transaction (%llu, %p, %u) != "
			       "journal->j_running_transaction (%p, %u)",
			       journal->j_devname,
			       (unsigned long long) bh->b_blocknr,
			       jh->b_transaction,
			       jh->b_transaction ? jh->b_transaction->t_tid : 0,
			       journal->j_running_transaction,
			       journal->j_running_transaction ?
			       journal->j_running_transaction->t_tid : 0);
			ret = -EINVAL;
		}
1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165
		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");
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
		if (unlikely(jh->b_transaction !=
			     journal->j_committing_transaction)) {
			printk(KERN_EMERG "JBD: %s: "
			       "jh->b_transaction (%llu, %p, %u) != "
			       "journal->j_committing_transaction (%p, %u)",
			       journal->j_devname,
			       (unsigned long long) bh->b_blocknr,
			       jh->b_transaction,
			       jh->b_transaction ? jh->b_transaction->t_tid : 0,
			       journal->j_committing_transaction,
			       journal->j_committing_transaction ?
			       journal->j_committing_transaction->t_tid : 0);
			ret = -EINVAL;
		}
		if (unlikely(jh->b_next_transaction != transaction)) {
			printk(KERN_EMERG "JBD: %s: "
			       "jh->b_next_transaction (%llu, %p, %u) != "
			       "transaction (%p, %u)",
			       journal->j_devname,
			       (unsigned long long) bh->b_blocknr,
			       jh->b_next_transaction,
			       jh->b_next_transaction ?
			       jh->b_next_transaction->t_tid : 0,
			       transaction, transaction->t_tid);
			ret = -EINVAL;
		}
1192 1193 1194 1195 1196 1197
		/* 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: */
1198
	J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1199 1200 1201

	JBUFFER_TRACE(jh, "file as BJ_Metadata");
	spin_lock(&journal->j_list_lock);
1202
	__jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1203 1204 1205 1206 1207
	spin_unlock(&journal->j_list_lock);
out_unlock_bh:
	jbd_unlock_bh_state(bh);
out:
	JBUFFER_TRACE(jh, "exit");
1208
	WARN_ON(ret);	/* All errors are bugs, so dump the stack */
1209
	return ret;
1210 1211 1212
}

/**
1213
 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228
 * @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.
 */
1229
int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1230 1231 1232 1233 1234 1235
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	struct journal_head *jh;
	int drop_reserve = 0;
	int err = 0;
1236
	int was_modified = 0;
1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254

	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;
	}

1255
	/* keep track of whether or not this transaction modified us */
1256 1257
	was_modified = jh->b_modified;

1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274
	/*
	 * 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");

1275 1276 1277 1278 1279 1280
		/*
		 * we only want to drop a reference if this transaction
		 * modified the buffer
		 */
		if (was_modified)
			drop_reserve = 1;
1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294

		/*
		 * 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) {
1295 1296
			__jbd2_journal_temp_unlink_buffer(jh);
			__jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1297
		} else {
1298
			__jbd2_journal_unfile_buffer(jh);
1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317
			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;
1318 1319 1320 1321 1322 1323 1324

			/*
			 * only drop a reference if this transaction modified
			 * the buffer
			 */
			if (was_modified)
				drop_reserve = 1;
1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340
		}
	}

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;
}

/**
1341
 * int jbd2_journal_stop() - complete a transaction
1342 1343 1344 1345 1346 1347 1348 1349 1350
 * @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.
 *
1351
 * jbd2_journal_stop itself will not usually return an error, but it may
1352
 * do so in unusual circumstances.  In particular, expect it to
1353
 * return -EIO if a jbd2_journal_abort has been executed since the
1354 1355
 * transaction began.
 */
1356
int jbd2_journal_stop(handle_t *handle)
1357 1358 1359
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
1360 1361
	int err, wait_for_commit = 0;
	tid_t tid;
1362 1363 1364 1365 1366 1367
	pid_t pid;

	J_ASSERT(journal_current_handle() == handle);

	if (is_handle_aborted(handle))
		err = -EIO;
1368
	else {
1369
		J_ASSERT(atomic_read(&transaction->t_updates) > 0);
1370
		err = 0;
1371
	}
1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383

	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
J
Josef Bacik 已提交
1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401
	 * 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...
	 *
	 * We try and optimize the sleep time against what the
	 * underlying disk can do, instead of having a static sleep
	 * time.  This is useful for the case where our storage is so
	 * fast that it is more optimal to go ahead and force a flush
	 * and wait for the transaction to be committed than it is to
	 * wait for an arbitrary amount of time for new writers to
	 * join the transaction.  We achieve this by measuring how
	 * long it takes to commit a transaction, and compare it with
	 * how long this transaction has been running, and if run time
	 * < commit time then we sleep for the delta and commit.  This
	 * greatly helps super fast disks that would see slowdowns as
	 * more threads started doing fsyncs.
1402
	 *
J
Josef Bacik 已提交
1403 1404 1405 1406
	 * 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.
1407 1408 1409
	 */
	pid = current->pid;
	if (handle->h_sync && journal->j_last_sync_writer != pid) {
J
Josef Bacik 已提交
1410 1411
		u64 commit_time, trans_time;

1412
		journal->j_last_sync_writer = pid;
J
Josef Bacik 已提交
1413

1414
		read_lock(&journal->j_state_lock);
J
Josef Bacik 已提交
1415
		commit_time = journal->j_average_commit_time;
1416
		read_unlock(&journal->j_state_lock);
J
Josef Bacik 已提交
1417 1418 1419 1420

		trans_time = ktime_to_ns(ktime_sub(ktime_get(),
						   transaction->t_start_time));

1421 1422
		commit_time = max_t(u64, commit_time,
				    1000*journal->j_min_batch_time);
J
Josef Bacik 已提交
1423
		commit_time = min_t(u64, commit_time,
1424
				    1000*journal->j_max_batch_time);
J
Josef Bacik 已提交
1425 1426 1427 1428 1429 1430 1431

		if (trans_time < commit_time) {
			ktime_t expires = ktime_add_ns(ktime_get(),
						       commit_time);
			set_current_state(TASK_UNINTERRUPTIBLE);
			schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
		}
1432 1433
	}

1434 1435
	if (handle->h_sync)
		transaction->t_synchronous_commit = 1;
1436
	current->journal_info = NULL;
1437 1438
	atomic_sub(handle->h_buffer_credits,
		   &transaction->t_outstanding_credits);
1439 1440 1441 1442 1443 1444 1445 1446

	/*
	 * 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 ||
1447 1448 1449
	    (atomic_read(&transaction->t_outstanding_credits) >
	     journal->j_max_transaction_buffers) ||
	    time_after_eq(jiffies, transaction->t_expires)) {
1450 1451 1452 1453 1454 1455 1456
		/* Do this even for aborted journals: an abort still
		 * completes the commit thread, it just doesn't write
		 * anything to disk. */

		jbd_debug(2, "transaction too old, requesting commit for "
					"handle %p\n", handle);
		/* This is non-blocking */
1457
		jbd2_log_start_commit(journal, transaction->t_tid);
1458 1459

		/*
1460
		 * Special case: JBD2_SYNC synchronous updates require us
1461 1462 1463
		 * to wait for the commit to complete.
		 */
		if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1464
			wait_for_commit = 1;
1465 1466
	}

1467 1468
	/*
	 * Once we drop t_updates, if it goes to zero the transaction
L
Lucas De Marchi 已提交
1469
	 * could start committing on us and eventually disappear.  So
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482
	 * once we do this, we must not dereference transaction
	 * pointer again.
	 */
	tid = transaction->t_tid;
	if (atomic_dec_and_test(&transaction->t_updates)) {
		wake_up(&journal->j_wait_updates);
		if (journal->j_barrier_count)
			wake_up(&journal->j_wait_transaction_locked);
	}

	if (wait_for_commit)
		err = jbd2_log_wait_commit(journal, tid);

1483
	lock_map_release(&handle->h_lockdep_map);
M
Mingming Cao 已提交
1484

M
Mingming Cao 已提交
1485
	jbd2_free_handle(handle);
1486 1487 1488
	return err;
}

R
Randy Dunlap 已提交
1489 1490
/**
 * int jbd2_journal_force_commit() - force any uncommitted transactions
1491 1492 1493 1494 1495 1496
 * @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.
 */
1497
int jbd2_journal_force_commit(journal_t *journal)
1498 1499 1500 1501
{
	handle_t *handle;
	int ret;

1502
	handle = jbd2_journal_start(journal, 1);
1503 1504 1505 1506
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
	} else {
		handle->h_sync = 1;
1507
		ret = jbd2_journal_stop(handle);
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 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567
	}
	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
1568 1569 1570 1571
 * bh->b_transaction->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 these pointers, it could go bad.  Generally the caller needs to re-read
 * the pointer from the transaction_t.
1572
 *
1573
 * Called under j_list_lock.
1574
 */
1575
static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587
{
	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)
1588
		J_ASSERT_JH(jh, transaction != NULL);
1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620

	switch (jh->b_jlist) {
	case BJ_None:
		return;
	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;
	}

	__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 */
}

1621 1622 1623 1624 1625 1626 1627 1628
/*
 * Remove buffer from all transactions.
 *
 * Called with bh_state lock and j_list_lock
 *
 * jh and bh may be already freed when this function returns.
 */
static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1629
{
1630
	__jbd2_journal_temp_unlink_buffer(jh);
1631
	jh->b_transaction = NULL;
1632
	jbd2_journal_put_journal_head(jh);
1633 1634
}

1635
void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1636
{
1637 1638 1639 1640 1641
	struct buffer_head *bh = jh2bh(jh);

	/* Get reference so that buffer cannot be freed before we unlock it */
	get_bh(bh);
	jbd_lock_bh_state(bh);
1642
	spin_lock(&journal->j_list_lock);
1643
	__jbd2_journal_unfile_buffer(jh);
1644
	spin_unlock(&journal->j_list_lock);
1645 1646
	jbd_unlock_bh_state(bh);
	__brelse(bh);
1647 1648 1649
}

/*
1650
 * Called from jbd2_journal_try_to_free_buffers().
1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663
 *
 * 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;

1664
	if (jh->b_next_transaction != NULL)
1665 1666 1667
		goto out;

	spin_lock(&journal->j_list_lock);
1668
	if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1669
		/* written-back checkpointed metadata buffer */
1670 1671
		JBUFFER_TRACE(jh, "remove from checkpoint list");
		__jbd2_journal_remove_checkpoint(jh);
1672 1673 1674 1675 1676 1677 1678
	}
	spin_unlock(&journal->j_list_lock);
out:
	return;
}

/**
1679
 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1680 1681
 * @journal: journal for operation
 * @page: to try and free
1682 1683 1684
 * @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.
1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697
 *
 *
 * 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
1698
 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1699 1700 1701 1702
 *
 * This may *change* the value of transaction_t->t_datalist, so anyone
 * who looks at t_datalist needs to lock against this function.
 *
1703 1704
 * 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()
1705 1706 1707 1708 1709 1710 1711 1712
 * 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?
1713 1714
 *
 * Return 0 on failure, 1 on success
1715
 */
1716
int jbd2_journal_try_to_free_buffers(journal_t *journal,
1717
				struct page *page, gfp_t gfp_mask)
1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732
{
	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
1733
		 * jbd2_journal_put_journal_head().
1734
		 */
1735
		jh = jbd2_journal_grab_journal_head(bh);
1736 1737 1738 1739 1740
		if (!jh)
			continue;

		jbd_lock_bh_state(bh);
		__journal_try_to_free_buffer(journal, bh);
1741
		jbd2_journal_put_journal_head(jh);
1742 1743 1744 1745
		jbd_unlock_bh_state(bh);
		if (buffer_jbd(bh))
			goto busy;
	} while ((bh = bh->b_this_page) != head);
1746

1747
	ret = try_to_free_buffers(page);
1748

1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771
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);

	if (jh->b_cp_transaction) {
		JBUFFER_TRACE(jh, "on running+cp transaction");
1772
		__jbd2_journal_temp_unlink_buffer(jh);
1773 1774 1775 1776 1777 1778
		/*
		 * We don't want to write the buffer anymore, clear the
		 * bit so that we don't confuse checks in
		 * __journal_file_buffer
		 */
		clear_buffer_dirty(bh);
1779
		__jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1780 1781 1782
		may_free = 0;
	} else {
		JBUFFER_TRACE(jh, "on running transaction");
1783
		__jbd2_journal_unfile_buffer(jh);
1784 1785 1786 1787 1788
	}
	return may_free;
}

/*
1789
 * jbd2_journal_invalidatepage
1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834
 *
 * 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.
 */
1835 1836
static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
				int partial_page)
1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852
{
	transaction_t *transaction;
	struct journal_head *jh;
	int may_free = 1;

	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;

1853
	/* OK, we have data buffer in journaled mode */
1854
	write_lock(&journal->j_state_lock);
1855 1856 1857
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);

1858
	jh = jbd2_journal_grab_journal_head(bh);
1859 1860 1861
	if (!jh)
		goto zap_buffer_no_jh;

1862 1863 1864 1865 1866 1867 1868 1869 1870 1871
	/*
	 * We cannot remove the buffer from checkpoint lists until the
	 * transaction adding inode to orphan list (let's call it T)
	 * is committed.  Otherwise if the transaction changing the
	 * buffer would be cleaned from the journal before T is
	 * committed, a crash will cause that the correct contents of
	 * the buffer will be lost.  On the other hand we have to
	 * clear the buffer dirty bit at latest at the moment when the
	 * transaction marking the buffer as freed in the filesystem
	 * structures is committed because from that moment on the
1872
	 * block can be reallocated and used by a different page.
1873 1874 1875
	 * Since the block hasn't been freed yet but the inode has
	 * already been added to orphan list, it is safe for us to add
	 * the buffer to BJ_Forget list of the newest transaction.
1876 1877 1878 1879 1880 1881 1882 1883
	 *
	 * Also we have to clear buffer_mapped flag of a truncated buffer
	 * because the buffer_head may be attached to the page straddling
	 * i_size (can happen only when blocksize < pagesize) and thus the
	 * buffer_head can be reused when the file is extended again. So we end
	 * up keeping around invalidated buffers attached to transactions'
	 * BJ_Forget list just to stop checkpointing code from cleaning up
	 * the transaction this buffer was modified in.
1884
	 */
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
	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");
1910
			may_free = __dispose_buffer(jh,
1911
					journal->j_running_transaction);
1912
			goto zap_buffer;
1913 1914 1915 1916 1917 1918 1919
		} 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");
1920
				may_free = __dispose_buffer(jh,
1921
					journal->j_committing_transaction);
1922
				goto zap_buffer;
1923 1924 1925 1926 1927 1928 1929 1930
			} 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) {
1931
		JBUFFER_TRACE(jh, "on committing transaction");
1932
		/*
1933
		 * The buffer is committing, we simply cannot touch
1934 1935 1936 1937 1938 1939 1940 1941
		 * it. If the page is straddling i_size we have to wait
		 * for commit and try again.
		 */
		if (partial_page) {
			jbd2_journal_put_journal_head(jh);
			spin_unlock(&journal->j_list_lock);
			jbd_unlock_bh_state(bh);
			write_unlock(&journal->j_state_lock);
1942
			return -EBUSY;
1943 1944 1945 1946 1947 1948
		}
		/*
		 * OK, buffer won't be reachable after truncate. We just set
		 * j_next_transaction to the running transaction (if there is
		 * one) and mark buffer as freed so that commit code knows it
		 * should clear dirty bits when it is done with the buffer.
1949
		 */
1950
		set_buffer_freed(bh);
1951 1952
		if (journal->j_running_transaction && buffer_jbddirty(bh))
			jh->b_next_transaction = journal->j_running_transaction;
1953
		jbd2_journal_put_journal_head(jh);
1954 1955
		spin_unlock(&journal->j_list_lock);
		jbd_unlock_bh_state(bh);
1956
		write_unlock(&journal->j_state_lock);
1957 1958 1959 1960 1961 1962 1963 1964 1965
		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);
1966
		JBUFFER_TRACE(jh, "on running transaction");
1967 1968 1969 1970
		may_free = __dispose_buffer(jh, transaction);
	}

zap_buffer:
1971 1972 1973 1974 1975 1976 1977 1978 1979
	/*
	 * This is tricky. Although the buffer is truncated, it may be reused
	 * if blocksize < pagesize and it is attached to the page straddling
	 * EOF. Since the buffer might have been added to BJ_Forget list of the
	 * running transaction, journal_get_write_access() won't clear
	 * b_modified and credit accounting gets confused. So clear b_modified
	 * here.
	 */
	jh->b_modified = 0;
1980
	jbd2_journal_put_journal_head(jh);
1981 1982 1983
zap_buffer_no_jh:
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(bh);
1984
	write_unlock(&journal->j_state_lock);
1985 1986 1987 1988 1989 1990
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);
1991 1992
	clear_buffer_delay(bh);
	clear_buffer_unwritten(bh);
1993 1994 1995 1996 1997
	bh->b_bdev = NULL;
	return may_free;
}

/**
1998
 * void jbd2_journal_invalidatepage()
1999 2000 2001 2002
 * @journal: journal to use for flush...
 * @page:    page to flush
 * @offset:  length of page to invalidate.
 *
2003 2004 2005
 * Reap page buffers containing data after offset in page. Can return -EBUSY
 * if buffers are part of the committing transaction and the page is straddling
 * i_size. Caller then has to wait for current commit and try again.
2006
 */
2007 2008 2009
int jbd2_journal_invalidatepage(journal_t *journal,
				struct page *page,
				unsigned long offset)
2010 2011 2012 2013
{
	struct buffer_head *head, *bh, *next;
	unsigned int curr_off = 0;
	int may_free = 1;
2014
	int ret = 0;
2015 2016 2017 2018

	if (!PageLocked(page))
		BUG();
	if (!page_has_buffers(page))
2019
		return 0;
2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032

	/* 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);
2033
			ret = journal_unmap_buffer(journal, bh, offset > 0);
2034
			unlock_buffer(bh);
2035 2036 2037
			if (ret < 0)
				return ret;
			may_free &= ret;
2038 2039 2040 2041 2042 2043 2044 2045 2046 2047
		}
		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));
	}
2048
	return 0;
2049 2050 2051 2052 2053
}

/*
 * File a buffer on the given transaction list.
 */
2054
void __jbd2_journal_file_buffer(struct journal_head *jh,
2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065
			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 ||
2066
				jh->b_transaction == NULL);
2067 2068 2069 2070 2071 2072

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

	if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
	    jlist == BJ_Shadow || jlist == BJ_Forget) {
2073 2074 2075 2076 2077 2078 2079 2080 2081
		/*
		 * For metadata buffers, we track dirty bit in buffer_jbddirty
		 * instead of buffer_dirty. We should not see a dirty bit set
		 * here because we clear it in do_get_write_access but e.g.
		 * tune2fs can modify the sb and set the dirty bit at any time
		 * so we try to gracefully handle that.
		 */
		if (buffer_dirty(bh))
			warn_dirty_buffer(bh);
2082 2083 2084 2085 2086 2087
		if (test_clear_buffer_dirty(bh) ||
		    test_clear_buffer_jbddirty(bh))
			was_dirty = 1;
	}

	if (jh->b_transaction)
2088
		__jbd2_journal_temp_unlink_buffer(jh);
2089 2090
	else
		jbd2_journal_grab_journal_head(bh);
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 2118 2119 2120 2121 2122 2123 2124 2125
	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_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;
	}

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

	if (was_dirty)
		set_buffer_jbddirty(bh);
}

2126
void jbd2_journal_file_buffer(struct journal_head *jh,
2127 2128 2129 2130
				transaction_t *transaction, int jlist)
{
	jbd_lock_bh_state(jh2bh(jh));
	spin_lock(&transaction->t_journal->j_list_lock);
2131
	__jbd2_journal_file_buffer(jh, transaction, jlist);
2132 2133 2134 2135 2136 2137 2138 2139 2140 2141
	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.
 *
2142
 * Called under j_list_lock
2143
 * Called under jbd_lock_bh_state(jh2bh(jh))
2144 2145
 *
 * jh and bh may be already free when this function returns
2146
 */
2147
void __jbd2_journal_refile_buffer(struct journal_head *jh)
2148
{
2149
	int was_dirty, jlist;
2150 2151 2152 2153 2154 2155 2156 2157
	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) {
2158
		__jbd2_journal_unfile_buffer(jh);
2159 2160 2161 2162 2163 2164 2165 2166 2167
		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);
2168
	__jbd2_journal_temp_unlink_buffer(jh);
2169 2170 2171 2172 2173
	/*
	 * We set b_transaction here because b_next_transaction will inherit
	 * our jh reference and thus __jbd2_journal_file_buffer() must not
	 * take a new one.
	 */
2174 2175
	jh->b_transaction = jh->b_next_transaction;
	jh->b_next_transaction = NULL;
2176 2177 2178 2179 2180 2181 2182
	if (buffer_freed(bh))
		jlist = BJ_Forget;
	else if (jh->b_modified)
		jlist = BJ_Metadata;
	else
		jlist = BJ_Reserved;
	__jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
2183 2184 2185 2186 2187 2188 2189
	J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);

	if (was_dirty)
		set_buffer_jbddirty(bh);
}

/*
2190 2191 2192 2193
 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
 * bh reference so that we can safely unlock bh.
 *
 * The jh and bh may be freed by this call.
2194
 */
2195
void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2196 2197 2198
{
	struct buffer_head *bh = jh2bh(jh);

2199 2200
	/* Get reference so that buffer cannot be freed before we unlock it */
	get_bh(bh);
2201 2202
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);
2203
	__jbd2_journal_refile_buffer(jh);
2204 2205 2206 2207
	jbd_unlock_bh_state(bh);
	spin_unlock(&journal->j_list_lock);
	__brelse(bh);
}
2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245

/*
 * File inode in the inode list of the handle's transaction
 */
int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;

	if (is_handle_aborted(handle))
		return -EIO;

	jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
			transaction->t_tid);

	/*
	 * First check whether inode isn't already on the transaction's
	 * lists without taking the lock. Note that this check is safe
	 * without the lock as we cannot race with somebody removing inode
	 * from the transaction. The reason is that we remove inode from the
	 * transaction only in journal_release_jbd_inode() and when we commit
	 * the transaction. We are guarded from the first case by holding
	 * a reference to the inode. We are safe against the second case
	 * because if jinode->i_transaction == transaction, commit code
	 * cannot touch the transaction because we hold reference to it,
	 * and if jinode->i_next_transaction == transaction, commit code
	 * will only file the inode where we want it.
	 */
	if (jinode->i_transaction == transaction ||
	    jinode->i_next_transaction == transaction)
		return 0;

	spin_lock(&journal->j_list_lock);

	if (jinode->i_transaction == transaction ||
	    jinode->i_next_transaction == transaction)
		goto done;

2246 2247 2248 2249 2250 2251 2252
	/*
	 * We only ever set this variable to 1 so the test is safe. Since
	 * t_need_data_flush is likely to be set, we do the test to save some
	 * cacheline bouncing
	 */
	if (!transaction->t_need_data_flush)
		transaction->t_need_data_flush = 1;
2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272
	/* On some different transaction's list - should be
	 * the committing one */
	if (jinode->i_transaction) {
		J_ASSERT(jinode->i_next_transaction == NULL);
		J_ASSERT(jinode->i_transaction ==
					journal->j_committing_transaction);
		jinode->i_next_transaction = transaction;
		goto done;
	}
	/* Not on any transaction list... */
	J_ASSERT(!jinode->i_next_transaction);
	jinode->i_transaction = transaction;
	list_add(&jinode->i_list, &transaction->t_inode_list);
done:
	spin_unlock(&journal->j_list_lock);

	return 0;
}

/*
2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290
 * File truncate and transaction commit interact with each other in a
 * non-trivial way.  If a transaction writing data block A is
 * committing, we cannot discard the data by truncate until we have
 * written them.  Otherwise if we crashed after the transaction with
 * write has committed but before the transaction with truncate has
 * committed, we could see stale data in block A.  This function is a
 * helper to solve this problem.  It starts writeout of the truncated
 * part in case it is in the committing transaction.
 *
 * Filesystem code must call this function when inode is journaled in
 * ordered mode before truncation happens and after the inode has been
 * placed on orphan list with the new inode size. The second condition
 * avoids the race that someone writes new data and we start
 * committing the transaction after this function has been called but
 * before a transaction for truncate is started (and furthermore it
 * allows us to optimize the case where the addition to orphan list
 * happens in the same transaction as write --- we don't have to write
 * any data in such case).
2291
 */
2292 2293
int jbd2_journal_begin_ordered_truncate(journal_t *journal,
					struct jbd2_inode *jinode,
2294 2295
					loff_t new_size)
{
2296
	transaction_t *inode_trans, *commit_trans;
2297 2298
	int ret = 0;

2299 2300
	/* This is a quick check to avoid locking if not necessary */
	if (!jinode->i_transaction)
2301
		goto out;
2302 2303 2304
	/* Locks are here just to force reading of recent values, it is
	 * enough that the transaction was not committing before we started
	 * a transaction adding the inode to orphan list */
2305
	read_lock(&journal->j_state_lock);
2306
	commit_trans = journal->j_committing_transaction;
2307
	read_unlock(&journal->j_state_lock);
2308 2309 2310 2311 2312
	spin_lock(&journal->j_list_lock);
	inode_trans = jinode->i_transaction;
	spin_unlock(&journal->j_list_lock);
	if (inode_trans == commit_trans) {
		ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
2313 2314 2315 2316 2317 2318 2319
			new_size, LLONG_MAX);
		if (ret)
			jbd2_journal_abort(journal, ret);
	}
out:
	return ret;
}