[PATCH] jbd2: initial copy of files from jbd

#

# Makefile for the linux journaling routines.

#

obj-$(CONFIG_JBD) += jbd.o

jbd-objs := transaction.o commit.o recovery.o checkpoint.o revoke.o journal.o

/*

 * linux/fs/checkpoint.c

 *

 * Written by Stephen C. Tweedie <sct@redhat.com>, 1999

 *

 * Copyright 1999 Red Hat Software --- 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.

 *

 * Checkpoint routines for the generic filesystem journaling code.

 * Part of the ext2fs journaling system.

 *

 * Checkpointing is the process of ensuring that a section of the log is

 * committed fully to disk, so that that portion of the log can be

 * reused.

 */

#include <linux/time.h>

#include <linux/fs.h>

#include <linux/jbd.h>

#include <linux/errno.h>

#include <linux/slab.h>

/*

 * Unlink a buffer from a transaction checkpoint list.

 *

 * Called with j_list_lock held.

 */

static inline void __buffer_unlink_first(struct journal_head *jh)

{

	transaction_t *transaction = jh->b_cp_transaction;

	jh->b_cpnext->b_cpprev = jh->b_cpprev;

	jh->b_cpprev->b_cpnext = jh->b_cpnext;

	if (transaction->t_checkpoint_list == jh) {

		transaction->t_checkpoint_list = jh->b_cpnext;

		if (transaction->t_checkpoint_list == jh)

			transaction->t_checkpoint_list = NULL;

	}

}

/*

 * Unlink a buffer from a transaction checkpoint(io) list.

 *

 * Called with j_list_lock held.

 */

static inline void __buffer_unlink(struct journal_head *jh)

{

	transaction_t *transaction = jh->b_cp_transaction;

	__buffer_unlink_first(jh);

	if (transaction->t_checkpoint_io_list == jh) {

		transaction->t_checkpoint_io_list = jh->b_cpnext;

		if (transaction->t_checkpoint_io_list == jh)

			transaction->t_checkpoint_io_list = NULL;

	}

}

/*

 * Move a buffer from the checkpoint list to the checkpoint io list

 *

 * Called with j_list_lock held

 */

static inline void __buffer_relink_io(struct journal_head *jh)

{

	transaction_t *transaction = jh->b_cp_transaction;

	__buffer_unlink_first(jh);

	if (!transaction->t_checkpoint_io_list) {

		jh->b_cpnext = jh->b_cpprev = jh;

	} else {

		jh->b_cpnext = transaction->t_checkpoint_io_list;

		jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;

		jh->b_cpprev->b_cpnext = jh;

		jh->b_cpnext->b_cpprev = jh;

	}

	transaction->t_checkpoint_io_list = jh;

}

/*

 * Try to release a checkpointed buffer from its transaction.

 * Returns 1 if we released it and 2 if we also released the

 * whole transaction.

 *

 * Requires j_list_lock

 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it

 */

static int __try_to_free_cp_buf(struct journal_head *jh)

{

	int ret = 0;

	struct buffer_head *bh = jh2bh(jh);

	if (jh->b_jlist == BJ_None && !buffer_locked(bh) && !buffer_dirty(bh)) {

		JBUFFER_TRACE(jh, "remove from checkpoint list");

		ret = __journal_remove_checkpoint(jh) + 1;

		jbd_unlock_bh_state(bh);

		journal_remove_journal_head(bh);

		BUFFER_TRACE(bh, "release");

		__brelse(bh);

	} else {

		jbd_unlock_bh_state(bh);

	}

	return ret;

}

/*

 * __log_wait_for_space: wait until there is space in the journal.

 *

 * Called under j-state_lock *only*.  It will be unlocked if we have to wait

 * for a checkpoint to free up some space in the log.

 */

void __log_wait_for_space(journal_t *journal)

{

	int nblocks;

	assert_spin_locked(&journal->j_state_lock);

	nblocks = jbd_space_needed(journal);

	while (__log_space_left(journal) < nblocks) {

		if (journal->j_flags & JFS_ABORT)

			return;

		spin_unlock(&journal->j_state_lock);

		mutex_lock(&journal->j_checkpoint_mutex);

		/*

		 * Test again, another process may have checkpointed while we

		 * were waiting for the checkpoint lock

		 */

		spin_lock(&journal->j_state_lock);

		nblocks = jbd_space_needed(journal);

		if (__log_space_left(journal) < nblocks) {

			spin_unlock(&journal->j_state_lock);

			log_do_checkpoint(journal);

			spin_lock(&journal->j_state_lock);

		}

		mutex_unlock(&journal->j_checkpoint_mutex);

	}

}

/*

 * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.

 * The caller must restart a list walk.  Wait for someone else to run

 * jbd_unlock_bh_state().

 */

static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)

	__releases(journal->j_list_lock)

{

	get_bh(bh);

	spin_unlock(&journal->j_list_lock);

	jbd_lock_bh_state(bh);

	jbd_unlock_bh_state(bh);

	put_bh(bh);

}

/*

 * Clean up transaction's list of buffers submitted for io.

 * We wait for any pending IO to complete and remove any clean

 * buffers. Note that we take the buffers in the opposite ordering

 * from the one in which they were submitted for IO.

 *

 * Called with j_list_lock held.

 */

static void __wait_cp_io(journal_t *journal, transaction_t *transaction)

{

	struct journal_head *jh;

	struct buffer_head *bh;

	tid_t this_tid;

	int released = 0;

	this_tid = transaction->t_tid;

restart:

	/* Did somebody clean up the transaction in the meanwhile? */

	if (journal->j_checkpoint_transactions != transaction ||

			transaction->t_tid != this_tid)

		return;

	while (!released && transaction->t_checkpoint_io_list) {

		jh = transaction->t_checkpoint_io_list;

		bh = jh2bh(jh);

		if (!jbd_trylock_bh_state(bh)) {

			jbd_sync_bh(journal, bh);

			spin_lock(&journal->j_list_lock);

			goto restart;

		}

		if (buffer_locked(bh)) {

			atomic_inc(&bh->b_count);

			spin_unlock(&journal->j_list_lock);

			jbd_unlock_bh_state(bh);

			wait_on_buffer(bh);

			/* the journal_head may have gone by now */

			BUFFER_TRACE(bh, "brelse");

			__brelse(bh);

			spin_lock(&journal->j_list_lock);

			goto restart;

		}

		/*

		 * Now in whatever state the buffer currently is, we know that

		 * it has been written out and so we can drop it from the list

		 */

		released = __journal_remove_checkpoint(jh);

		jbd_unlock_bh_state(bh);

		journal_remove_journal_head(bh);

		__brelse(bh);

	}

}

#define NR_BATCH	64

static void

__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)

{

	int i;

	ll_rw_block(SWRITE, *batch_count, bhs);

	for (i = 0; i < *batch_count; i++) {

		struct buffer_head *bh = bhs[i];

		clear_buffer_jwrite(bh);

		BUFFER_TRACE(bh, "brelse");

		__brelse(bh);

	}

	*batch_count = 0;

}

/*

 * Try to flush one buffer from the checkpoint list to disk.

 *

 * Return 1 if something happened which requires us to abort the current

 * scan of the checkpoint list.

 *

 * Called with j_list_lock held and drops it if 1 is returned

 * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it

 */

static int __process_buffer(journal_t *journal, struct journal_head *jh,

			struct buffer_head **bhs, int *batch_count)

{

	struct buffer_head *bh = jh2bh(jh);

	int ret = 0;

	if (buffer_locked(bh)) {

		atomic_inc(&bh->b_count);

		spin_unlock(&journal->j_list_lock);

		jbd_unlock_bh_state(bh);

		wait_on_buffer(bh);

		/* the journal_head may have gone by now */

		BUFFER_TRACE(bh, "brelse");

		__brelse(bh);

		ret = 1;

	} else if (jh->b_transaction != NULL) {

		transaction_t *t = jh->b_transaction;

		tid_t tid = t->t_tid;

		spin_unlock(&journal->j_list_lock);

		jbd_unlock_bh_state(bh);

		log_start_commit(journal, tid);

		log_wait_commit(journal, tid);

		ret = 1;

	} else if (!buffer_dirty(bh)) {

		J_ASSERT_JH(jh, !buffer_jbddirty(bh));

		BUFFER_TRACE(bh, "remove from checkpoint");

		__journal_remove_checkpoint(jh);

		spin_unlock(&journal->j_list_lock);

		jbd_unlock_bh_state(bh);

		journal_remove_journal_head(bh);

		__brelse(bh);

		ret = 1;

	} else {

		/*

		 * Important: we are about to write the buffer, and

		 * possibly block, while still holding the journal lock.

		 * We cannot afford to let the transaction logic start

		 * messing around with this buffer before we write it to

		 * disk, as that would break recoverability.

		 */

		BUFFER_TRACE(bh, "queue");

		get_bh(bh);

		J_ASSERT_BH(bh, !buffer_jwrite(bh));

		set_buffer_jwrite(bh);

		bhs[*batch_count] = bh;

		__buffer_relink_io(jh);

		jbd_unlock_bh_state(bh);

		(*batch_count)++;

		if (*batch_count == NR_BATCH) {

			spin_unlock(&journal->j_list_lock);

			__flush_batch(journal, bhs, batch_count);

			ret = 1;

		}

	}

	return ret;

}

/*

 * Perform an actual checkpoint. We take the first transaction on the

 * list of transactions to be checkpointed and send all its buffers

 * to disk. We submit larger chunks of data at once.

 *

 * The journal should be locked before calling this function.

 */

int log_do_checkpoint(journal_t *journal)

{

	transaction_t *transaction;

	tid_t this_tid;

	int result;

	jbd_debug(1, "Start checkpoint\n");

	/*

	 * First thing: if there are any transactions in the log which

	 * don't need checkpointing, just eliminate them from the

	 * journal straight away.

	 */

	result = cleanup_journal_tail(journal);

	jbd_debug(1, "cleanup_journal_tail returned %d\n", result);

	if (result <= 0)

		return result;

	/*

	 * OK, we need to start writing disk blocks.  Take one transaction

	 * and write it.

	 */

	spin_lock(&journal->j_list_lock);

	if (!journal->j_checkpoint_transactions)

		goto out;

	transaction = journal->j_checkpoint_transactions;

	this_tid = transaction->t_tid;

restart:

	/*

	 * If someone cleaned up this transaction while we slept, we're

	 * done (maybe it's a new transaction, but it fell at the same

	 * address).

	 */

	if (journal->j_checkpoint_transactions == transaction &&

			transaction->t_tid == this_tid) {

		int batch_count = 0;

		struct buffer_head *bhs[NR_BATCH];

		struct journal_head *jh;

		int retry = 0;

		while (!retry && transaction->t_checkpoint_list) {

			struct buffer_head *bh;

			jh = transaction->t_checkpoint_list;

			bh = jh2bh(jh);

			if (!jbd_trylock_bh_state(bh)) {

				jbd_sync_bh(journal, bh);

				retry = 1;

				break;

			}

			retry = __process_buffer(journal, jh, bhs,&batch_count);

			if (!retry && lock_need_resched(&journal->j_list_lock)){

				spin_unlock(&journal->j_list_lock);

				retry = 1;

				break;

			}

		}

		if (batch_count) {

			if (!retry) {

				spin_unlock(&journal->j_list_lock);

				retry = 1;

			}

			__flush_batch(journal, bhs, &batch_count);

		}

		if (retry) {

			spin_lock(&journal->j_list_lock);

			goto restart;

		}

		/*

		 * Now we have cleaned up the first transaction's checkpoint

		 * list. Let's clean up the second one

		 */

		__wait_cp_io(journal, transaction);

	}

out:

	spin_unlock(&journal->j_list_lock);

	result = cleanup_journal_tail(journal);

	if (result < 0)

		return result;

	return 0;

}

/*

 * Check the list of checkpoint transactions for the journal to see if

 * we have already got rid of any since the last update of the log tail

 * in the journal superblock.  If so, we can instantly roll the

 * superblock forward to remove those transactions from the log.

 *

 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.

 *

 * Called with the journal lock held.

 *

 * This is the only part of the journaling code which really needs to be

 * aware of transaction aborts.  Checkpointing involves writing to the

 * main filesystem area rather than to the journal, so it can proceed

 * even in abort state, but we must not update the journal superblock if

 * we have an abort error outstanding.

 */

int cleanup_journal_tail(journal_t *journal)

{

	transaction_t * transaction;

	tid_t		first_tid;

	unsigned long	blocknr, freed;

	/* OK, work out the oldest transaction remaining in the log, and

	 * the log block it starts at.

	 *

	 * If the log is now empty, we need to work out which is the

	 * next transaction ID we will write, and where it will

	 * start. */

	spin_lock(&journal->j_state_lock);

	spin_lock(&journal->j_list_lock);

	transaction = journal->j_checkpoint_transactions;

	if (transaction) {

		first_tid = transaction->t_tid;

		blocknr = transaction->t_log_start;

	} else if ((transaction = journal->j_committing_transaction) != NULL) {

		first_tid = transaction->t_tid;

		blocknr = transaction->t_log_start;

	} else if ((transaction = journal->j_running_transaction) != NULL) {

		first_tid = transaction->t_tid;

		blocknr = journal->j_head;

	} else {

		first_tid = journal->j_transaction_sequence;

		blocknr = journal->j_head;

	}

	spin_unlock(&journal->j_list_lock);

	J_ASSERT(blocknr != 0);

	/* If the oldest pinned transaction is at the tail of the log

           already then there's not much we can do right now. */

	if (journal->j_tail_sequence == first_tid) {

		spin_unlock(&journal->j_state_lock);

		return 1;

	}

	/* OK, update the superblock to recover the freed space.

	 * Physical blocks come first: have we wrapped beyond the end of

	 * the log?  */

	freed = blocknr - journal->j_tail;

	if (blocknr < journal->j_tail)

		freed = freed + journal->j_last - journal->j_first;

	jbd_debug(1,

		  "Cleaning journal tail from %d to %d (offset %lu), "

		  "freeing %lu\n",

		  journal->j_tail_sequence, first_tid, blocknr, freed);

	journal->j_free += freed;

	journal->j_tail_sequence = first_tid;

	journal->j_tail = blocknr;

	spin_unlock(&journal->j_state_lock);

	if (!(journal->j_flags & JFS_ABORT))

		journal_update_superblock(journal, 1);

	return 0;

}

/* Checkpoint list management */

/*

 * journal_clean_one_cp_list

 *

 * Find all the written-back checkpoint buffers in the given list and release them.

 *

 * Called with the journal locked.

 * Called with j_list_lock held.

 * Returns number of bufers reaped (for debug)

 */

static int journal_clean_one_cp_list(struct journal_head *jh, int *released)

{

	struct journal_head *last_jh;

	struct journal_head *next_jh = jh;

	int ret, freed = 0;

	*released = 0;

	if (!jh)

		return 0;

	last_jh = jh->b_cpprev;

	do {

		jh = next_jh;

		next_jh = jh->b_cpnext;

		/* Use trylock because of the ranking */

		if (jbd_trylock_bh_state(jh2bh(jh))) {

			ret = __try_to_free_cp_buf(jh);

			if (ret) {

				freed++;

				if (ret == 2) {

					*released = 1;

					return freed;

				}

			}

		}

		/*

		 * This function only frees up some memory

		 * if possible so we dont have an obligation

		 * to finish processing. Bail out if preemption

		 * requested:

		 */

		if (need_resched())

			return freed;

	} while (jh != last_jh);

	return freed;

}

/*

 * journal_clean_checkpoint_list

 *

 * Find all the written-back checkpoint buffers in the journal and release them.

 *

 * Called with the journal locked.

 * Called with j_list_lock held.

 * Returns number of buffers reaped (for debug)

 */

int __journal_clean_checkpoint_list(journal_t *journal)

{

	transaction_t *transaction, *last_transaction, *next_transaction;

	int ret = 0;

	int released;

	transaction = journal->j_checkpoint_transactions;

	if (!transaction)

		goto out;

	last_transaction = transaction->t_cpprev;

	next_transaction = transaction;

	do {

		transaction = next_transaction;

		next_transaction = transaction->t_cpnext;

		ret += journal_clean_one_cp_list(transaction->

				t_checkpoint_list, &released);

		/*

		 * This function only frees up some memory if possible so we

		 * dont have an obligation to finish processing. Bail out if

		 * preemption requested:

		 */

		if (need_resched())

			goto out;

		if (released)

			continue;

		/*

		 * It is essential that we are as careful as in the case of

		 * t_checkpoint_list with removing the buffer from the list as

		 * we can possibly see not yet submitted buffers on io_list

		 */

		ret += journal_clean_one_cp_list(transaction->

				t_checkpoint_io_list, &released);

		if (need_resched())

			goto out;

	} while (transaction != last_transaction);

out:

	return ret;

}

/*

 * journal_remove_checkpoint: called after a buffer has been committed

 * to disk (either by being write-back flushed to disk, or being

 * committed to the log).

 *

 * We cannot safely clean a transaction out of the log until all of the

 * buffer updates committed in that transaction have safely been stored

 * elsewhere on disk.  To achieve this, all of the buffers in a

 * transaction need to be maintained on the transaction's checkpoint

 * lists until they have been rewritten, at which point this function is

 * called to remove the buffer from the existing transaction's

 * checkpoint lists.

 *

 * The function returns 1 if it frees the transaction, 0 otherwise.

 *

 * This function is called with the journal locked.

 * This function is called with j_list_lock held.

 * This function is called with jbd_lock_bh_state(jh2bh(jh))

 */

int __journal_remove_checkpoint(struct journal_head *jh)

{

	transaction_t *transaction;

	journal_t *journal;

	int ret = 0;

	JBUFFER_TRACE(jh, "entry");

	if ((transaction = jh->b_cp_transaction) == NULL) {

		JBUFFER_TRACE(jh, "not on transaction");

		goto out;

	}

	journal = transaction->t_journal;

	__buffer_unlink(jh);

	jh->b_cp_transaction = NULL;

	if (transaction->t_checkpoint_list != NULL ||

	    transaction->t_checkpoint_io_list != NULL)

		goto out;

	JBUFFER_TRACE(jh, "transaction has no more buffers");

	/*

	 * There is one special case to worry about: if we have just pulled the

	 * buffer off a committing transaction's forget list, then even if the

	 * checkpoint list is empty, the transaction obviously cannot be

	 * dropped!

	 *

	 * The locking here around j_committing_transaction is a bit sleazy.

	 * See the comment at the end of journal_commit_transaction().

	 */

	if (transaction == journal->j_committing_transaction) {

		JBUFFER_TRACE(jh, "belongs to committing transaction");

		goto out;

	}

	/* OK, that was the last buffer for the transaction: we can now

	   safely remove this transaction from the log */

	__journal_drop_transaction(journal, transaction);

	/* Just in case anybody was waiting for more transactions to be

           checkpointed... */

	wake_up(&journal->j_wait_logspace);

	ret = 1;

out:

	JBUFFER_TRACE(jh, "exit");

	return ret;

}

/*

 * journal_insert_checkpoint: put a committed buffer onto a checkpoint

 * list so that we know when it is safe to clean the transaction out of

 * the log.

 *

 * Called with the journal locked.

 * Called with j_list_lock held.

 */

void __journal_insert_checkpoint(struct journal_head *jh,

			       transaction_t *transaction)

{

	JBUFFER_TRACE(jh, "entry");

	J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));

	J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);

	jh->b_cp_transaction = transaction;

	if (!transaction->t_checkpoint_list) {

		jh->b_cpnext = jh->b_cpprev = jh;

	} else {

		jh->b_cpnext = transaction->t_checkpoint_list;

		jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;

		jh->b_cpprev->b_cpnext = jh;

		jh->b_cpnext->b_cpprev = jh;

	}

	transaction->t_checkpoint_list = jh;

}

/*

 * We've finished with this transaction structure: adios...

 *

 * The transaction must have no links except for the checkpoint by this

 * point.

 *

 * Called with the journal locked.

 * Called with j_list_lock held.

 */

void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)

{

	assert_spin_locked(&journal->j_list_lock);

	if (transaction->t_cpnext) {

		transaction->t_cpnext->t_cpprev = transaction->t_cpprev;

		transaction->t_cpprev->t_cpnext = transaction->t_cpnext;

		if (journal->j_checkpoint_transactions == transaction)

			journal->j_checkpoint_transactions =

				transaction->t_cpnext;

		if (journal->j_checkpoint_transactions == transaction)

			journal->j_checkpoint_transactions = NULL;

	}

	J_ASSERT(transaction->t_state == T_FINISHED);

	J_ASSERT(transaction->t_buffers == NULL);

	J_ASSERT(transaction->t_sync_datalist == NULL);

	J_ASSERT(transaction->t_forget == NULL);

	J_ASSERT(transaction->t_iobuf_list == NULL);

	J_ASSERT(transaction->t_shadow_list == NULL);

	J_ASSERT(transaction->t_log_list == NULL);

	J_ASSERT(transaction->t_checkpoint_list == NULL);

	J_ASSERT(transaction->t_checkpoint_io_list == NULL);

	J_ASSERT(transaction->t_updates == 0);

	J_ASSERT(journal->j_committing_transaction != transaction);

	J_ASSERT(journal->j_running_transaction != transaction);

	jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);

	kfree(transaction);

}