/*
* linux/fs/checkpoint.c
- *
+ *
* Written by Stephen C. Tweedie <sct@redhat.com>, 1999
*
* Copyright 1999 Red Hat Software --- All Rights Reserved
* 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.
+ * 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
#include <linux/slab.h>
/*
- * Unlink a buffer from a transaction.
+ * Unlink a buffer from a transaction checkpoint list.
*
* Called with j_list_lock held.
*/
-
-static inline void __buffer_unlink(struct journal_head *jh)
+static inline void __buffer_unlink_first(struct journal_head *jh)
{
- transaction_t *transaction;
-
- transaction = jh->b_cp_transaction;
- jh->b_cp_transaction = NULL;
+ 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)
+ if (transaction->t_checkpoint_list == jh) {
transaction->t_checkpoint_list = jh->b_cpnext;
- if (transaction->t_checkpoint_list == jh)
- transaction->t_checkpoint_list = NULL;
+ 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.
+ * 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
*/
if (jh->b_jlist == BJ_None && !buffer_locked(bh) && !buffer_dirty(bh)) {
JBUFFER_TRACE(jh, "remove from checkpoint list");
- __journal_remove_checkpoint(jh);
+ ret = __journal_remove_checkpoint(jh) + 1;
jbd_unlock_bh_state(bh);
journal_remove_journal_head(bh);
BUFFER_TRACE(bh, "release");
__brelse(bh);
- ret = 1;
} else {
jbd_unlock_bh_state(bh);
}
if (journal->j_flags & JFS_ABORT)
return;
spin_unlock(&journal->j_state_lock);
- down(&journal->j_checkpoint_sem);
+ mutex_lock(&journal->j_checkpoint_mutex);
/*
* Test again, another process may have checkpointed while we
log_do_checkpoint(journal);
spin_lock(&journal->j_state_lock);
}
- up(&journal->j_checkpoint_sem);
+ mutex_unlock(&journal->j_checkpoint_mutex);
}
}
* 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);
}
/*
- * Clean up a transaction's checkpoint list.
- *
- * We wait for any pending IO to complete and make sure any clean
- * buffers are removed from the transaction.
- *
- * Return 1 if we performed any actions which might have destroyed the
- * checkpoint. (journal_remove_checkpoint() deletes the transaction when
- * the last checkpoint buffer is cleansed)
+ * 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 int __cleanup_transaction(journal_t *journal, transaction_t *transaction)
+static void __wait_cp_io(journal_t *journal, transaction_t *transaction)
{
- struct journal_head *jh, *next_jh, *last_jh;
+ struct journal_head *jh;
struct buffer_head *bh;
- int ret = 0;
-
- assert_spin_locked(&journal->j_list_lock);
- jh = transaction->t_checkpoint_list;
- if (!jh)
- return 0;
-
- last_jh = jh->b_cpprev;
- next_jh = jh;
- do {
- jh = next_jh;
+ 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);
- goto out_return_1;
+ spin_lock(&journal->j_list_lock);
+ goto restart;
}
-
/*
- * This is foul
+ * 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
*/
- if (!jbd_trylock_bh_state(bh)) {
- jbd_sync_bh(journal, bh);
- goto out_return_1;
- }
-
- 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);
- goto out_return_1;
- }
-
- /*
- * AKPM: I think the buffer_jbddirty test is redundant - it
- * shouldn't have NULL b_transaction?
- */
- next_jh = jh->b_cpnext;
- if (!buffer_dirty(bh) && !buffer_jbddirty(bh)) {
- BUFFER_TRACE(bh, "remove from checkpoint");
- __journal_remove_checkpoint(jh);
- jbd_unlock_bh_state(bh);
- journal_remove_journal_head(bh);
- __brelse(bh);
- ret = 1;
- } else {
- jbd_unlock_bh_state(bh);
- }
- } while (jh != last_jh);
-
- return ret;
-out_return_1:
- spin_lock(&journal->j_list_lock);
- return 1;
+ released = __journal_remove_checkpoint(jh);
+ jbd_unlock_bh_state(bh);
+ journal_remove_journal_head(bh);
+ __brelse(bh);
+ }
}
#define NR_BATCH 64
{
int i;
- spin_unlock(&journal->j_list_lock);
ll_rw_block(SWRITE, *batch_count, bhs);
- spin_lock(&journal->j_list_lock);
for (i = 0; i < *batch_count; i++) {
struct buffer_head *bh = bhs[i];
clear_buffer_jwrite(bh);
* 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.
+ * scan of the checkpoint list.
*
- * Called with j_list_lock held.
+ * 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 __flush_buffer(journal_t *journal, struct journal_head *jh,
- struct buffer_head **bhs, int *batch_count,
- int *drop_count)
+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_dirty(bh) && !buffer_locked(bh) && jh->b_jlist == BJ_None) {
- J_ASSERT_JH(jh, jh->b_transaction == NULL);
+ 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.
+ * 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;
}
- } else {
- int last_buffer = 0;
- if (jh->b_cpnext == jh) {
- /* We may be about to drop the transaction. Tell the
- * caller that the lists have changed.
- */
- last_buffer = 1;
- }
- if (__try_to_free_cp_buf(jh)) {
- (*drop_count)++;
- ret = last_buffer;
- }
}
return ret;
}
/*
- * Perform an actual checkpoint. We don't write out only enough to
- * satisfy the current blocked requests: rather we submit a reasonably
- * sized chunk of the outstanding data to disk at once for
- * efficiency. __log_wait_for_space() will retry if we didn't free enough.
- *
- * However, we _do_ take into account the amount requested so that once
- * the IO has been queued, we can return as soon as enough of it has
- * completed to disk.
+ * 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;
- int batch_count = 0;
- struct buffer_head *bhs[NR_BATCH];
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.
+ * journal straight away.
*/
result = cleanup_journal_tail(journal);
jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
return result;
/*
- * OK, we need to start writing disk blocks. Try to free up a
- * quarter of the log in a single checkpoint if we can.
+ * 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:
/*
- * AKPM: check this code. I had a feeling a while back that it
- * degenerates into a busy loop at unmount time.
+ * 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).
*/
- spin_lock(&journal->j_list_lock);
- while (journal->j_checkpoint_transactions) {
- transaction_t *transaction;
- struct journal_head *jh, *last_jh, *next_jh;
- int drop_count = 0;
- int cleanup_ret, retry = 0;
- tid_t this_tid;
-
- transaction = journal->j_checkpoint_transactions;
- this_tid = transaction->t_tid;
- jh = transaction->t_checkpoint_list;
- last_jh = jh->b_cpprev;
- next_jh = jh;
- do {
+ 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 = next_jh;
- next_jh = jh->b_cpnext;
+ jh = transaction->t_checkpoint_list;
bh = jh2bh(jh);
if (!jbd_trylock_bh_state(bh)) {
jbd_sync_bh(journal, bh);
- spin_lock(&journal->j_list_lock);
retry = 1;
break;
}
- retry = __flush_buffer(journal, jh, bhs, &batch_count, &drop_count);
- if (cond_resched_lock(&journal->j_list_lock)) {
+ 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;
}
- } while (jh != last_jh && !retry);
+ }
if (batch_count) {
+ if (!retry) {
+ spin_unlock(&journal->j_list_lock);
+ retry = 1;
+ }
__flush_batch(journal, bhs, &batch_count);
- retry = 1;
}
+ if (retry) {
+ spin_lock(&journal->j_list_lock);
+ goto restart;
+ }
/*
- * If someone cleaned up this transaction while we slept, we're
- * done
- */
- if (journal->j_checkpoint_transactions != transaction)
- break;
- if (retry)
- continue;
- /*
- * Maybe it's a new transaction, but it fell at the same
- * address
- */
- if (transaction->t_tid != this_tid)
- continue;
- /*
- * We have walked the whole transaction list without
- * finding anything to write to disk. We had better be
- * able to make some progress or we are in trouble.
+ * Now we have cleaned up the first transaction's checkpoint
+ * list. Let's clean up the second one
*/
- cleanup_ret = __cleanup_transaction(journal, transaction);
- J_ASSERT(drop_count != 0 || cleanup_ret != 0);
- if (journal->j_checkpoint_transactions != transaction)
- break;
+ __wait_cp_io(journal, transaction);
}
+out:
spin_unlock(&journal->j_list_lock);
result = cleanup_journal_tail(journal);
if (result < 0)
return result;
-
return 0;
}
* 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
unsigned long blocknr, freed;
/* OK, work out the oldest transaction remaining in the log, and
- * the log block it starts at.
- *
+ * 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. */
/* 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
*
*
* Called with the journal locked.
* Called with j_list_lock held.
- * Returns number of bufers reaped (for debug)
+ * 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 == 0)
+ if (!transaction)
goto out;
last_transaction = transaction->t_cpprev;
next_transaction = transaction;
do {
- struct journal_head *jh;
-
transaction = next_transaction;
next_transaction = transaction->t_cpnext;
- jh = transaction->t_checkpoint_list;
- if (jh) {
- struct journal_head *last_jh = jh->b_cpprev;
- struct journal_head *next_jh = jh;
-
- do {
- jh = next_jh;
- next_jh = jh->b_cpnext;
- /* Use trylock because of the ranknig */
- if (jbd_trylock_bh_state(jh2bh(jh)))
- ret += __try_to_free_cp_buf(jh);
- /*
- * 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;
- } while (jh != last_jh);
- }
+ 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).
* 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
- * list until they have been rewritten, at which point this function is
+ * lists until they have been rewritten, at which point this function is
* called to remove the buffer from the existing transaction's
- * checkpoint list.
+ * 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))
*/
-void __journal_remove_checkpoint(struct journal_head *jh)
+int __journal_remove_checkpoint(struct journal_head *jh)
{
transaction_t *transaction;
journal_t *journal;
+ int ret = 0;
JBUFFER_TRACE(jh, "entry");
journal = transaction->t_journal;
__buffer_unlink(jh);
+ jh->b_cp_transaction = NULL;
- if (transaction->t_checkpoint_list != NULL)
+ if (transaction->t_checkpoint_list != NULL ||
+ transaction->t_checkpoint_io_list != NULL)
goto out;
JBUFFER_TRACE(jh, "transaction has no more buffers");
/* 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;
}
/*
* Called with the journal locked.
* Called with j_list_lock held.
*/
-void __journal_insert_checkpoint(struct journal_head *jh,
+void __journal_insert_checkpoint(struct journal_head *jh,
transaction_t *transaction)
{
JBUFFER_TRACE(jh, "entry");
/*
* We've finished with this transaction structure: adios...
- *
+ *
* The transaction must have no links except for the checkpoint by this
* point.
*
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);
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