#include <linux/slab.h>
/*
- * Unlink a buffer from a transaction checkpoint list.
+ * Unlink a buffer from a transaction.
*
* Called with j_list_lock held.
*/
-static void __buffer_unlink_first(struct journal_head *jh)
+static inline void __buffer_unlink(struct journal_head *jh)
{
transaction_t *transaction;
transaction = jh->b_cp_transaction;
+ jh->b_cp_transaction = NULL;
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;
- }
-}
-
-/*
- * 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;
-
- 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;
-
- 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;
+ if (transaction->t_checkpoint_list == jh)
+ transaction->t_checkpoint_list = NULL;
}
/*
* Try to release a checkpointed buffer from its transaction.
- * Returns 1 if we released it and 2 if we also released the
- * whole transaction.
- *
+ * Returns 1 if we released it.
* 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");
- ret = __journal_remove_checkpoint(jh) + 1;
+ __journal_remove_checkpoint(jh);
jbd_unlock_bh_state(bh);
journal_remove_journal_head(bh);
BUFFER_TRACE(bh, "release");
__brelse(bh);
+ ret = 1;
} else {
jbd_unlock_bh_state(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.
+ * 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)
*
* Called with j_list_lock held.
*/
-
-static void __wait_cp_io(journal_t *journal, transaction_t *transaction)
+static int __cleanup_transaction(journal_t *journal, transaction_t *transaction)
{
- struct journal_head *jh;
+ struct journal_head *jh, *next_jh, *last_jh;
struct buffer_head *bh;
- tid_t this_tid;
- int released = 0;
-
- this_tid = transaction->t_tid;
-restart:
- /* Didn't 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;
+ 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;
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;
+ goto out_return_1;
}
+
/*
- * 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
+ * This is foul
*/
- released = __journal_remove_checkpoint(jh);
- jbd_unlock_bh_state(bh);
- }
+ 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;
}
#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);
* 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 with j_list_lock held.
* 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)
+static int __flush_buffer(journal_t *journal, struct journal_head *jh,
+ struct buffer_head **bhs, int *batch_count,
+ int *drop_count)
{
struct buffer_head *bh = jh2bh(jh);
int ret = 0;
- if (buffer_locked(bh)) {
- get_bh(bh);
- 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");
- put_bh(bh);
- ret = 1;
- }
- else if (jh->b_transaction != NULL) {
- transaction_t *t = jh->b_transaction;
- tid_t tid = t->t_tid;
+ if (buffer_dirty(bh) && !buffer_locked(bh) && jh->b_jlist == BJ_None) {
+ J_ASSERT_JH(jh, jh->b_transaction == NULL);
- 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);
- put_bh(bh);
- ret = 1;
- }
- else {
/*
* Important: we are about to write the buffer, and
* possibly block, while still holding the journal lock.
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 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.
+ * 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.
+ *
* 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");
return result;
/*
- * OK, we need to start writing disk blocks. Take one transaction
- * and write it.
+ * OK, we need to start writing disk blocks. Try to free up a
+ * quarter of the log in a single checkpoint if we can.
*/
- 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).
+ * AKPM: check this code. I had a feeling a while back that it
+ * degenerates into a busy loop at unmount time.
*/
- 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) {
+ 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 {
struct buffer_head *bh;
- jh = transaction->t_checkpoint_list;
+ jh = next_jh;
+ next_jh = jh->b_cpnext;
bh = jh2bh(jh);
if (!jbd_trylock_bh_state(bh)) {
jbd_sync_bh(journal, bh);
+ spin_lock(&journal->j_list_lock);
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 = __flush_buffer(journal, jh, bhs, &batch_count, &drop_count);
+ if (cond_resched_lock(&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;
- }
/*
- * Now we have cleaned up the first transaction's checkpoint
- * list. Let's clean up the second one.
+ * 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
*/
- __wait_cp_io(journal, transaction);
+ 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.
+ */
+ cleanup_ret = __cleanup_transaction(journal, transaction);
+ J_ASSERT(drop_count != 0 || cleanup_ret != 0);
+ if (journal->j_checkpoint_transactions != transaction)
+ break;
}
-out:
spin_unlock(&journal->j_list_lock);
result = cleanup_journal_tail(journal);
if (result < 0)
return result;
+
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
*
*
* Called with the journal locked.
* Called with j_list_lock held.
- * Returns number of buffers reaped (for debug)
+ * Returns number of bufers reaped (for debug)
*/
int __journal_clean_checkpoint_list(journal_t *journal)
{
transaction_t *transaction, *last_transaction, *next_transaction;
- int ret = 0, released;
+ int ret = 0;
transaction = journal->j_checkpoint_transactions;
- if (!transaction)
+ if (transaction == 0)
goto out;
last_transaction = transaction->t_cpprev;
next_transaction = transaction;
do {
+ struct journal_head *jh;
+
transaction = next_transaction;
next_transaction = transaction->t_cpnext;
- ret += journal_clean_one_cp_list(transaction->
- t_checkpoint_list, &released);
- 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;
+ 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);
+ }
} while (transaction != last_transaction);
out:
return ret;
* 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
+ * list 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.
+ * checkpoint list.
*
* 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)
+void __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 ||
- transaction->t_checkpoint_io_list != NULL)
+ if (transaction->t_checkpoint_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;
}
/*
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);
projects / linux-2.6 / commitdiff