[PATCH] JBD: remove journal_datalist_lock

This was a system-wide spinlock.

Simple transformation: make it a filesystem-wide spinlock, in the JBD
journal.

That's a bit lame, and later it might be nice to make it per-transaction_t.
But there are interesting ranking and ordering problems with that, especially
around __journal_refile_buffer().

fs/jbd/checkpoint.c

@@ -23,12 +23,10 @@
 #include <linux/errno.h>
 #include <linux/slab.h>
 
-extern spinlock_t journal_datalist_lock;
-
 /*
  * Unlink a buffer from a transaction. 
  *
- * Called with journal_datalist_lock held.
+ * Called with j_list_lock held.
  */
 
 static inline void __buffer_unlink(struct journal_head *jh)
@@ -49,7 +47,7 @@ static inline void __buffer_unlink(struct journal_head *jh)
 /*
  * Try to release a checkpointed buffer from its transaction.
  * Returns 1 if we released it.
- * Requires journal_datalist_lock
+ * 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)
@@ -97,14 +95,14 @@ void log_wait_for_space(journal_t *journal, int nblocks)
 }
 
 /*
- * We were unable to perform jbd_trylock_bh_state() inside
- * journal_datalist_lock.  The caller must restart a list walk.  Wait for
- * someone else to run jbd_unlock_bh_state().
+ * 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)
 {
 	get_bh(bh);
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 	jbd_lock_bh_state(bh);
 	jbd_unlock_bh_state(bh);
 	put_bh(bh);
@@ -121,7 +119,7 @@ static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
  * the last checkpoint buffer is cleansed)
  *
  * Called with the journal locked.
- * Called with journal_datalist_lock held.
+ * Called with j_list_lock held.
  */
 static int __cleanup_transaction(journal_t *journal, transaction_t *transaction)
 {
@@ -129,7 +127,7 @@ static int __cleanup_transaction(journal_t *journal, transaction_t *transaction)
 	struct buffer_head *bh;
 	int ret = 0;
 
-	assert_spin_locked(&journal_datalist_lock);
+	assert_spin_locked(&journal->j_list_lock);
 	jh = transaction->t_checkpoint_list;
 	if (!jh)
 		return 0;
@@ -141,7 +139,7 @@ static int __cleanup_transaction(journal_t *journal, transaction_t *transaction)
 		bh = jh2bh(jh);
 		if (buffer_locked(bh)) {
 			atomic_inc(&bh->b_count);
-			spin_unlock(&journal_datalist_lock);
+			spin_unlock(&journal->j_list_lock);
 			unlock_journal(journal);
 			wait_on_buffer(bh);
 			/* the journal_head may have gone by now */
@@ -162,7 +160,7 @@ static int __cleanup_transaction(journal_t *journal, transaction_t *transaction)
 			transaction_t *transaction = jh->b_transaction;
 			tid_t tid = transaction->t_tid;
 
-			spin_unlock(&journal_datalist_lock);
+			spin_unlock(&journal->j_list_lock);
 			jbd_unlock_bh_state(bh);
 			log_start_commit(journal, transaction);
 			unlock_journal(journal);
@@ -196,20 +194,20 @@ static int __cleanup_transaction(journal_t *journal, transaction_t *transaction)
 	return ret;
 out_return_1:
 	lock_journal(journal);
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 	return 1;
 }
 
 #define NR_BATCH	64
 
-static void __flush_batch(struct buffer_head **bhs, int *batch_count)
+static void
+__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
 {
 	int i;
 
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 	ll_rw_block(WRITE, *batch_count, bhs);
-	blk_run_queues();
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 	for (i = 0; i < *batch_count; i++) {
 		struct buffer_head *bh = bhs[i];
 		clear_bit(BH_JWrite, &bh->b_state);
@@ -225,7 +223,7 @@ static void __flush_batch(struct buffer_head **bhs, int *batch_count)
  * Return 1 if something happened which requires us to abort the current
  * scan of the checkpoint list.  
  *
- * Called with journal_datalist_lock held.
+ * Called with j_list_lock held.
  * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
  */
 static int __flush_buffer(journal_t *journal, struct journal_head *jh,
@@ -253,7 +251,7 @@ static int __flush_buffer(journal_t *journal, struct journal_head *jh,
 		jbd_unlock_bh_state(bh);
 		(*batch_count)++;
 		if (*batch_count == NR_BATCH) {
-			__flush_batch(bhs, batch_count);
+			__flush_batch(journal, bhs, batch_count);
 			ret = 1;
 		}
 	} else {
@@ -287,7 +285,7 @@ static int __flush_buffer(journal_t *journal, struct journal_head *jh,
  */
 
 /* @@@ `nblocks' is unused.  Should it be used? */
-int log_do_checkpoint (journal_t *journal, int nblocks)
+int log_do_checkpoint(journal_t *journal, int nblocks)
 {
 	transaction_t *transaction, *last_transaction, *next_transaction;
 	int result;
@@ -314,7 +312,7 @@ int log_do_checkpoint (journal_t *journal, int nblocks)
 	 * AKPM: check this code.  I had a feeling a while back that it
 	 * degenerates into a busy loop at unmount time.
 	 */
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 repeat:
 	transaction = journal->j_checkpoint_transactions;
 	if (transaction == NULL)
@@ -340,14 +338,14 @@ int log_do_checkpoint (journal_t *journal, int nblocks)
 			bh = jh2bh(jh);
 			if (!jbd_trylock_bh_state(bh)) {
 				jbd_sync_bh(journal, bh);
-				spin_lock(&journal_datalist_lock);
+				spin_lock(&journal->j_list_lock);
 				break;
 			}
 			retry = __flush_buffer(journal, jh, bhs, &batch_count,
 						&drop_count);
 		} while (jh != last_jh && !retry);
 		if (batch_count) {
-			__flush_batch(bhs, &batch_count);
+			__flush_batch(journal, bhs, &batch_count);
 			goto repeat;
 		}
 		if (retry)
@@ -363,7 +361,7 @@ int log_do_checkpoint (journal_t *journal, int nblocks)
 	} while (transaction != last_transaction);
 
 done:
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 	result = cleanup_journal_tail(journal);
 	if (result < 0)
 		return result;
@@ -402,7 +400,7 @@ int cleanup_journal_tail(journal_t *journal)
 	 * start. */
 
 	/* j_checkpoint_transactions needs locking */
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 	transaction = journal->j_checkpoint_transactions;
 	if (transaction) {
 		first_tid = transaction->t_tid;
@@ -417,7 +415,7 @@ int cleanup_journal_tail(journal_t *journal)
 		first_tid = journal->j_transaction_sequence;
 		blocknr = journal->j_head;
 	}
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 	J_ASSERT (blocknr != 0);
 
 	/* If the oldest pinned transaction is at the tail of the log
@@ -454,7 +452,7 @@ int cleanup_journal_tail(journal_t *journal)
  * Find all the written-back checkpoint buffers in the journal and release them.
  *
  * Called with the journal locked.
- * Called with journal_datalist_lock held.
+ * Called with j_list_lock held.
  * Returns number of bufers reaped (for debug)
  */
 
@@ -506,7 +504,7 @@ int __journal_clean_checkpoint_list(journal_t *journal)
  * checkpoint list.  
  *
  * This function is called with the journal locked.
- * This function is called with journal_datalist_lock held.
+ * This function is called with j_list_lock held.
  */
 
 void __journal_remove_checkpoint(struct journal_head *jh)
@@ -551,20 +549,13 @@ void __journal_remove_checkpoint(struct journal_head *jh)
 	JBUFFER_TRACE(jh, "exit");
 }
 
-void journal_remove_checkpoint(struct journal_head *jh)
-{
-	spin_lock(&journal_datalist_lock);
-	__journal_remove_checkpoint(jh);
-	spin_unlock(&journal_datalist_lock);
-}
-
 /*
  * 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 journal_datalist_lock held.
+ * Called with j_list_lock held.
  */
 void __journal_insert_checkpoint(struct journal_head *jh, 
 			       transaction_t *transaction)
@@ -573,7 +564,6 @@ void __journal_insert_checkpoint(struct journal_head *jh,
 	J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
 	J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
 
-	assert_spin_locked(&journal_datalist_lock);
 	jh->b_cp_transaction = transaction;
 
 	if (!transaction->t_checkpoint_list) {
@@ -587,14 +577,6 @@ void __journal_insert_checkpoint(struct journal_head *jh,
 	transaction->t_checkpoint_list = jh;
 }
 
-void journal_insert_checkpoint(struct journal_head *jh, 
-			       transaction_t *transaction)
-{
-	spin_lock(&journal_datalist_lock);
-	__journal_insert_checkpoint(jh, transaction);
-	spin_unlock(&journal_datalist_lock);
-}
-
 /*
  * We've finished with this transaction structure: adios...
  * 
@@ -602,12 +584,12 @@ void journal_insert_checkpoint(struct journal_head *jh,
  * point.
  *
  * Called with the journal locked.
- * Called with journal_datalist_lock held.
+ * Called with j_list_lock held.
  */
 
 void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
 {
-	assert_spin_locked(&journal_datalist_lock);
+	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;

fs/jbd/commit.c

@@ -20,8 +20,6 @@
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
 
-extern spinlock_t journal_datalist_lock;
-
 /*
  * Default IO end handler for temporary BJ_IO buffer_heads.
  */
@@ -67,9 +65,9 @@ void journal_commit_transaction(journal_t *journal)
 	lock_journal(journal); /* Protect journal->j_running_transaction */
 
 #ifdef COMMIT_STATS
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 	summarise_journal_usage(journal);
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 #endif
 
 	lock_kernel();
@@ -121,7 +119,7 @@ void journal_commit_transaction(journal_t *journal)
 	while (commit_transaction->t_reserved_list) {
 		jh = commit_transaction->t_reserved_list;
 		JBUFFER_TRACE(jh, "reserved, unused: refile");
-		journal_refile_buffer(jh);
+		journal_refile_buffer(journal, jh);
 	}
 
 	/*
@@ -129,9 +127,9 @@ void journal_commit_transaction(journal_t *journal)
 	 * checkpoint lists.  We do this *before* commit because it potentially
 	 * frees some memory
 	 */
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 	__journal_clean_checkpoint_list(journal);
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 
 	/* First part of the commit: force the revoke list out to disk.
 	 * The revoke code generates its own metadata blocks on disk for this.
@@ -185,10 +183,10 @@ void journal_commit_transaction(journal_t *journal)
 	 * Cleanup any flushed data buffers from the data list.  Even in
 	 * abort mode, we want to flush this out as soon as possible.
 	 *
-	 * We take journal_datalist_lock to protect the lists from
+	 * We take j_list_lock to protect the lists from
 	 * journal_try_to_free_buffers().
 	 */
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 
 write_out_data_locked:
 	bufs = 0;
@@ -214,9 +212,9 @@ void journal_commit_transaction(journal_t *journal)
 				 * We have a lock ranking problem..
 				 */
 				if (!jbd_trylock_bh_state(bh)) {
-					spin_unlock(&journal_datalist_lock);
+					spin_unlock(&journal->j_list_lock);
 					schedule();
-					spin_lock(&journal_datalist_lock);
+					spin_lock(&journal->j_list_lock);
 					break;
 				}
 				__journal_unfile_buffer(jh);
@@ -238,14 +236,14 @@ void journal_commit_transaction(journal_t *journal)
 
 	if (bufs || need_resched()) {
 		jbd_debug(2, "submit %d writes\n", bufs);
-		spin_unlock(&journal_datalist_lock);
+		spin_unlock(&journal->j_list_lock);
 		unlock_journal(journal);
 		if (bufs)
 			ll_rw_block(WRITE, bufs, wbuf);
 		cond_resched();
 		journal_brelse_array(wbuf, bufs);
 		lock_journal(journal);
-		spin_lock(&journal_datalist_lock);
+		spin_lock(&journal->j_list_lock);
 		if (bufs)
 			goto write_out_data_locked;
 	}
@@ -263,7 +261,7 @@ void journal_commit_transaction(journal_t *journal)
 		bh = jh2bh(jh);
 		if (buffer_locked(bh)) {
 			get_bh(bh);
-			spin_unlock(&journal_datalist_lock);
+			spin_unlock(&journal->j_list_lock);
 			unlock_journal(journal);
 			wait_on_buffer(bh);
 			if (unlikely(!buffer_uptodate(bh)))
@@ -279,7 +277,7 @@ void journal_commit_transaction(journal_t *journal)
 	goto write_out_data_locked;
 
 sync_datalist_empty:
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 
 	/*
 	 * If we found any dirty or locked buffers, then we should have
@@ -311,7 +309,7 @@ void journal_commit_transaction(journal_t *journal)
 
 		if (is_journal_aborted(journal)) {
 			JBUFFER_TRACE(jh, "journal is aborting: refile");
-			journal_refile_buffer(jh);
+			journal_refile_buffer(journal, jh);
 			/* If that was the last one, we need to clean up
 			 * any descriptor buffers which may have been
 			 * already allocated, even if we are now
@@ -462,7 +460,7 @@ void journal_commit_transaction(journal_t *journal)
 	jbd_debug(3, "JBD: commit phase 4\n");
 
 	/*
-	 * akpm: these are BJ_IO, and journal_datalist_lock is not needed.
+	 * akpm: these are BJ_IO, and j_list_lock is not needed.
 	 * See __journal_try_to_free_buffer.
 	 */
 wait_for_iobuf:
@@ -483,7 +481,7 @@ void journal_commit_transaction(journal_t *journal)
 		clear_buffer_jwrite(bh);
 
 		JBUFFER_TRACE(jh, "ph4: unfile after journal write");
-		journal_unfile_buffer(jh);
+		journal_unfile_buffer(journal, jh);
 
 		/*
 		 * akpm: don't put back a buffer_head with stale pointers
@@ -543,8 +541,8 @@ void journal_commit_transaction(journal_t *journal)
 		}
 
 		BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
-		clear_bit(BH_JWrite, &bh->b_state);
-		journal_unfile_buffer(jh);
+		clear_buffer_jwrite(bh);
+		journal_unfile_buffer(journal, jh);
 		jh->b_transaction = NULL;
 		journal_put_journal_head(jh);
 		__brelse(bh);		/* One for getblk */
@@ -664,7 +662,7 @@ void journal_commit_transaction(journal_t *journal)
 			jh->b_frozen_data = NULL;
 		}
 
-		spin_lock(&journal_datalist_lock);
+		spin_lock(&journal->j_list_lock);
 		cp_transaction = jh->b_cp_transaction;
 		if (cp_transaction) {
 			JBUFFER_TRACE(jh, "remove from old cp transaction");
@@ -706,7 +704,7 @@ void journal_commit_transaction(journal_t *journal)
 			journal_remove_journal_head(bh);
 			__brelse(bh);
 		}
-		spin_unlock(&journal_datalist_lock);
+		spin_unlock(&journal->j_list_lock);
 	}
 
 	/* Done with this transaction! */
@@ -720,7 +718,7 @@ void journal_commit_transaction(journal_t *journal)
 	journal->j_commit_sequence = commit_transaction->t_tid;
 	journal->j_committing_transaction = NULL;
 
-	spin_lock(&journal_datalist_lock);
+	spin_lock(&journal->j_list_lock);
 	if (commit_transaction->t_checkpoint_list == NULL) {
 		__journal_drop_transaction(journal, commit_transaction);
 	} else {
@@ -739,7 +737,7 @@ void journal_commit_transaction(journal_t *journal)
 				commit_transaction;
 		}
 	}
-	spin_unlock(&journal_datalist_lock);
+	spin_unlock(&journal->j_list_lock);
 
 	jbd_debug(1, "JBD: commit %d complete, head %d\n",
 		  journal->j_commit_sequence, journal->j_tail_sequence);

fs/jbd/journal.c

@@ -83,39 +83,6 @@ EXPORT_SYMBOL(journal_force_commit);
 
 static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
 
-/*
- * journal_datalist_lock is used to protect data buffers:
- *
- *	bh->b_transaction
- *	bh->b_tprev
- *	bh->b_tnext
- *
- * journal_free_buffer() is called from journal_try_to_free_buffer(), and is
- * async wrt everything else.
- *
- * It is also used for checkpoint data, also to protect against
- * journal_try_to_free_buffer():
- *
- *	bh->b_cp_transaction
- *	bh->b_cpnext
- *	bh->b_cpprev
- *	transaction->t_checkpoint_list
- *	transaction->t_cpnext
- *	transaction->t_cpprev
- *	journal->j_checkpoint_transactions
- *
- * It is global at this time rather than per-journal because it's
- * impossible for __journal_free_buffer to go from a buffer_head
- * back to a journal_t unracily (well, not true.  Fix later)
- *
- *
- * The `datalist' and `checkpoint list' functions are quite
- * separate and we could use two spinlocks here.
- *
- * lru_list_lock nests inside journal_datalist_lock.
- */
-spinlock_t journal_datalist_lock = SPIN_LOCK_UNLOCKED;
-
 /*
  * List of all journals in the system.  Protected by the BKL.
  */
@@ -1515,26 +1482,6 @@ int journal_blocks_per_page(struct inode *inode)
 	return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
 }
 
-/*
- * shrink_journal_memory().
- * Called when we're under memory pressure.  Free up all the written-back
- * checkpointed metadata buffers.
- */
-void shrink_journal_memory(void)
-{
-	struct list_head *list;
-
-	lock_kernel();
-	list_for_each(list, &all_journals) {
-		journal_t *journal =
-			list_entry(list, journal_t, j_all_journals);
-		spin_lock(&journal_datalist_lock);
-		__journal_clean_checkpoint_list(journal);
-		spin_unlock(&journal_datalist_lock);
-	}
-	unlock_kernel();
-}
-
 /*
  * Simple support for retying memory allocations.  Introduced to help to
  * debug different VM deadlock avoidance strategies. 
@@ -1660,7 +1607,6 @@ static void journal_free_journal_head(struct journal_head *jh)
  *
  * Doesn't need the journal lock.
  * May sleep.
- * Cannot be called with journal_datalist_lock held.
  */
 struct journal_head *journal_add_journal_head(struct buffer_head *bh)
 {

include/linux/jbd.h

@@ -836,10 +836,10 @@ struct journal_s
  */
 
 /* Filing buffers */
+extern void journal_unfile_buffer(journal_t *, struct journal_head *);
 extern void __journal_unfile_buffer(struct journal_head *);
-extern void journal_unfile_buffer(struct journal_head *);
 extern void __journal_refile_buffer(struct journal_head *);
-extern void journal_refile_buffer(struct journal_head *);
+extern void journal_refile_buffer(journal_t *, struct journal_head *);
 extern void __journal_file_buffer(struct journal_head *, transaction_t *, int);
 extern void __journal_free_buffer(struct journal_head *bh);
 extern void journal_file_buffer(struct journal_head *, transaction_t *, int);
@@ -854,10 +854,8 @@ extern void journal_commit_transaction(journal_t *);
 
 /* Checkpoint list management */
 int __journal_clean_checkpoint_list(journal_t *journal);
-extern void journal_remove_checkpoint(struct journal_head *);
-extern void __journal_remove_checkpoint(struct journal_head *);
-extern void journal_insert_checkpoint(struct journal_head *, transaction_t *);
-extern void __journal_insert_checkpoint(struct journal_head *,transaction_t *);
+void __journal_remove_checkpoint(struct journal_head *);
+void __journal_insert_checkpoint(struct journal_head *, transaction_t *);
 
 /* Buffer IO */
 extern int 
@@ -1017,9 +1015,6 @@ extern void	log_wait_for_space(journal_t *, int nblocks);
 extern void	__journal_drop_transaction(journal_t *, transaction_t *);
 extern int	cleanup_journal_tail(journal_t *);
 
-/* Reduce journal memory usage by flushing */
-extern void shrink_journal_memory(void);
-
 /* Debugging code only: */
 
 #define jbd_ENOSYS() \