Message-ID: <4EBA657E.6010506@whamcloud.com>
Date:	Wed, 09 Nov 2011 19:35:26 +0800
From:	Bobi Jam <bobijam@...mcloud.com>
To:	linux-ext4@...r.kernel.org
Subject: [PATCH v2] ext4: expand commit callback

The per-commit callback was used by mballoc code to manage free
space bitmaps after deleted blocks have been released. This patch
expand it to contain multiple different callbacks.

* add a ext4_journal_cb_entry to store journal callback function.
* add an ext4_journal_cb_entry member in ext4_free_data.
* transaction->t_private_list is used to link all journal callback
  entries.
* add ext4_journal_callback_add/del functions to add/deletel
  callback entry into/from jounal->j_private.

Signed-off-by: Bobi Jam <bobijam@...mcloud.com>
Signed-off-by: Andreas Dilger <adilger@...mcloud.com>
---
 fs/ext4/ext4_jbd2.h |   72 ++++++++++++++++++++++++
 fs/ext4/mballoc.c   |  151 ++++++++++++++++++++++++---------------------------
 fs/ext4/mballoc.h   |   18 ++++---
 fs/ext4/super.c     |   18 ++++++
 4 files changed, 171 insertions(+), 88 deletions(-)

diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 5802fa1..c65a774 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -104,6 +104,78 @@
 #define EXT4_MAXQUOTAS_INIT_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_INIT_BLOCKS(sb))
 #define EXT4_MAXQUOTAS_DEL_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_DEL_BLOCKS(sb))
 
+/**
+ *   struct ext4_journal_cb_entry - Base structure for callback information.
+ *
+ *   This struct is a 'seed' structure for a using with your own callback
+ *   structs. If you are using callbacks you must allocate one of these
+ *   or another struct of your own definition which has this struct
+ *   as it's first element and pass it to ext4_journal_callback_add().
+ */
+struct ext4_journal_cb_entry {
+	/* list information for other callbacks attached to the same handle */
+	struct list_head jce_list;
+
+	/*  Function to call with this callback structure */
+	void (*jce_func)(struct super_block *sb,
+			 struct ext4_journal_cb_entry *jce, int error);
+
+	/* user data goes here */
+};
+
+/**
+ * ext4_journal_callback_add: add a function to call after transaction commit
+ * @handle: active journal transaction handle to register callback on
+ * @func: callback function to call after the transaction has committed:
+ *        @sb: superblock of current filesystem for transaction
+ *        @jce: returned journal callback data
+ *        @rc: journal state at commit (0 = transaction committed properly)
+ * @jce: journal callback data (internal and function private data struct)
+ *
+ * The registered function will be called in the context of the journal thread
+ * after the transaction for which the handle was created has completed.
+ *
+ * No locks are held when the callback function is called, so it is safe to
+ * call blocking functions from within the callback, but the callback should
+ * not block or run for too long, or the filesystem will be blocked waiting for
+ * the next transaction to commit. No journaling functions can be used, or
+ * there is a risk of deadlock.
+ *
+ * There is no guaranteed calling order of multiple registered callbacks on
+ * the same transaction.
+ */
+static inline void ext4_journal_callback_add(handle_t *handle,
+			void (*func)(struct super_block *sb,
+				     struct ext4_journal_cb_entry *jce,
+				     int rc),
+			struct ext4_journal_cb_entry *jce)
+{
+	struct ext4_sb_info *sbi =
+			EXT4_SB(handle->h_transaction->t_journal->j_private);
+
+	/* Add the jce to transaction's private list */
+	jce->jce_func = func;
+	spin_lock(&sbi->s_md_lock);
+	list_add_tail(&jce->jce_list, &handle->h_transaction->t_private_list);
+	spin_unlock(&sbi->s_md_lock);
+}
+
+/**
+ * ext4_journal_callback_del: delete a registered callback
+ * @handle: active journal transaction handle on which callback was registered
+ * @jce: registered journal callback entry to unregister
+ */
+static inline void ext4_journal_callback_del(handle_t *handle,
+					     struct ext4_journal_cb_entry *jce)
+{
+	struct ext4_sb_info *sbi =
+			EXT4_SB(handle->h_transaction->t_journal->j_private);
+
+	spin_lock(&sbi->s_md_lock);
+	list_del_init(&jce->jce_list);
+	spin_unlock(&sbi->s_md_lock);
+}
+
 int
 ext4_mark_iloc_dirty(handle_t *handle,
 		     struct inode *inode,
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e2d8be8..fdf3f30 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -21,6 +21,7 @@
  * mballoc.c contains the multiblocks allocation routines
  */
 
+#include "ext4_jbd2.h"
 #include "mballoc.h"
 #include <linux/debugfs.h>
 #include <linux/slab.h>
@@ -339,7 +340,7 @@
  */
 static struct kmem_cache *ext4_pspace_cachep;
 static struct kmem_cache *ext4_ac_cachep;
-static struct kmem_cache *ext4_free_ext_cachep;
+static struct kmem_cache *ext4_free_data_cachep;
 
 /* We create slab caches for groupinfo data structures based on the
  * superblock block size.  There will be one per mounted filesystem for
@@ -357,7 +358,8 @@ static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
 					ext4_group_t group);
 static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
 						ext4_group_t group);
-static void release_blocks_on_commit(journal_t *journal, transaction_t *txn);
+static void ext4_free_data_callback(struct super_block *sb,
+				struct ext4_journal_cb_entry *jce, int rc);
 
 static inline void *mb_correct_addr_and_bit(int *bit, void *addr)
 {
@@ -2522,9 +2524,6 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
 		proc_create_data("mb_groups", S_IRUGO, sbi->s_proc,
 				 &ext4_mb_seq_groups_fops, sb);
 
-	if (sbi->s_journal)
-		sbi->s_journal->j_commit_callback = release_blocks_on_commit;
-
 	return 0;
 
 out_free_locality_groups:
@@ -2637,58 +2636,55 @@ static inline int ext4_issue_discard(struct super_block *sb,
  * This function is called by the jbd2 layer once the commit has finished,
  * so we know we can free the blocks that were released with that commit.
  */
-static void release_blocks_on_commit(journal_t *journal, transaction_t *txn)
+static void ext4_free_data_callback(struct super_block *sb,
+				    struct ext4_journal_cb_entry *jce,
+				    int rc)
 {
-	struct super_block *sb = journal->j_private;
+	struct ext4_free_data *entry = (struct ext4_free_data *)jce;
 	struct ext4_buddy e4b;
 	struct ext4_group_info *db;
 	int err, count = 0, count2 = 0;
-	struct ext4_free_data *entry;
-	struct list_head *l, *ltmp;
 
-	list_for_each_safe(l, ltmp, &txn->t_private_list) {
-		entry = list_entry(l, struct ext4_free_data, list);
+	mb_debug(1, "gonna free %u blocks in group %u (0x%p):",
+		 entry->efd_count, entry->efd_group, entry);
 
-		mb_debug(1, "gonna free %u blocks in group %u (0x%p):",
-			 entry->count, entry->group, entry);
+	if (test_opt(sb, DISCARD))
+		ext4_issue_discard(sb, entry->efd_group,
+				   entry->efd_start_cluster, entry->efd_count);
 
-		if (test_opt(sb, DISCARD))
-			ext4_issue_discard(sb, entry->group,
-					   entry->start_cluster, entry->count);
+	err = ext4_mb_load_buddy(sb, entry->efd_group, &e4b);
+	/* we expect to find existing buddy because it's pinned */
+	BUG_ON(err != 0);
 
-		err = ext4_mb_load_buddy(sb, entry->group, &e4b);
-		/* we expect to find existing buddy because it's pinned */
-		BUG_ON(err != 0);
 
-		db = e4b.bd_info;
-		/* there are blocks to put in buddy to make them really free */
-		count += entry->count;
-		count2++;
-		ext4_lock_group(sb, entry->group);
-		/* Take it out of per group rb tree */
-		rb_erase(&entry->node, &(db->bb_free_root));
-		mb_free_blocks(NULL, &e4b, entry->start_cluster, entry->count);
+	db = e4b.bd_info;
+	/* there are blocks to put in buddy to make them really free */
+	count += entry->efd_count;
+	count2++;
+	ext4_lock_group(sb, entry->efd_group);
+	/* Take it out of per group rb tree */
+	rb_erase(&entry->efd_node, &(db->bb_free_root));
+	mb_free_blocks(NULL, &e4b, entry->efd_start_cluster, entry->efd_count);
 
-		/*
-		 * Clear the trimmed flag for the group so that the next
-		 * ext4_trim_fs can trim it.
-		 * If the volume is mounted with -o discard, online discard
-		 * is supported and the free blocks will be trimmed online.
-		 */
-		if (!test_opt(sb, DISCARD))
-			EXT4_MB_GRP_CLEAR_TRIMMED(db);
+	/*
+	 * Clear the trimmed flag for the group so that the next
+	 * ext4_trim_fs can trim it.
+	 * If the volume is mounted with -o discard, online discard
+	 * is supported and the free blocks will be trimmed online.
+	 */
+	if (!test_opt(sb, DISCARD))
+		EXT4_MB_GRP_CLEAR_TRIMMED(db);
 
-		if (!db->bb_free_root.rb_node) {
-			/* No more items in the per group rb tree
-			 * balance refcounts from ext4_mb_free_metadata()
-			 */
-			page_cache_release(e4b.bd_buddy_page);
-			page_cache_release(e4b.bd_bitmap_page);
-		}
-		ext4_unlock_group(sb, entry->group);
-		kmem_cache_free(ext4_free_ext_cachep, entry);
-		ext4_mb_unload_buddy(&e4b);
+	if (!db->bb_free_root.rb_node) {
+		/* No more items in the per group rb tree
+		 * balance refcounts from ext4_mb_free_metadata()
+		 */
+		page_cache_release(e4b.bd_buddy_page);
+		page_cache_release(e4b.bd_bitmap_page);
 	}
+	ext4_unlock_group(sb, entry->efd_group);
+	kmem_cache_free(ext4_free_data_cachep, entry);
+	ext4_mb_unload_buddy(&e4b);
 
 	mb_debug(1, "freed %u blocks in %u structures\n", count, count2);
 }
@@ -2741,9 +2737,9 @@ int __init ext4_init_mballoc(void)
 		return -ENOMEM;
 	}
 
-	ext4_free_ext_cachep = KMEM_CACHE(ext4_free_data,
-					  SLAB_RECLAIM_ACCOUNT);
-	if (ext4_free_ext_cachep == NULL) {
+	ext4_free_data_cachep = KMEM_CACHE(ext4_free_data,
+					   SLAB_RECLAIM_ACCOUNT);
+	if (ext4_free_data_cachep == NULL) {
 		kmem_cache_destroy(ext4_pspace_cachep);
 		kmem_cache_destroy(ext4_ac_cachep);
 		return -ENOMEM;
@@ -2761,7 +2757,7 @@ void ext4_exit_mballoc(void)
 	rcu_barrier();
 	kmem_cache_destroy(ext4_pspace_cachep);
 	kmem_cache_destroy(ext4_ac_cachep);
-	kmem_cache_destroy(ext4_free_ext_cachep);
+	kmem_cache_destroy(ext4_free_data_cachep);
 	ext4_groupinfo_destroy_slabs();
 	ext4_remove_debugfs_entry();
 }
@@ -3321,8 +3317,8 @@ static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
 	n = rb_first(&(grp->bb_free_root));
 
 	while (n) {
-		entry = rb_entry(n, struct ext4_free_data, node);
-		ext4_set_bits(bitmap, entry->start_cluster, entry->count);
+		entry = rb_entry(n, struct ext4_free_data, efd_node);
+		ext4_set_bits(bitmap, entry->efd_start_cluster, entry->efd_count);
 		n = rb_next(n);
 	}
 	return;
@@ -4428,9 +4424,9 @@ out:
 static int can_merge(struct ext4_free_data *entry1,
 			struct ext4_free_data *entry2)
 {
-	if ((entry1->t_tid == entry2->t_tid) &&
-	    (entry1->group == entry2->group) &&
-	    ((entry1->start_cluster + entry1->count) == entry2->start_cluster))
+	if ((entry1->efd_tid == entry2->efd_tid) &&
+	    (entry1->efd_group == entry2->efd_group) &&
+	    ((entry1->efd_start_cluster + entry1->efd_count) == entry2->efd_start_cluster))
 		return 1;
 	return 0;
 }
@@ -4452,8 +4448,8 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
 	BUG_ON(e4b->bd_bitmap_page == NULL);
 	BUG_ON(e4b->bd_buddy_page == NULL);
 
-	new_node = &new_entry->node;
-	cluster = new_entry->start_cluster;
+	new_node = &new_entry->efd_node;
+	cluster = new_entry->efd_start_cluster;
 
 	if (!*n) {
 		/* first free block exent. We need to
@@ -4466,10 +4462,10 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
 	}
 	while (*n) {
 		parent = *n;
-		entry = rb_entry(parent, struct ext4_free_data, node);
-		if (cluster < entry->start_cluster)
+		entry = rb_entry(parent, struct ext4_free_data, efd_node);
+		if (cluster < entry->efd_start_cluster)
 			n = &(*n)->rb_left;
-		else if (cluster >= (entry->start_cluster + entry->count))
+		else if (cluster >= (entry->efd_start_cluster + entry->efd_count))
 			n = &(*n)->rb_right;
 		else {
 			ext4_grp_locked_error(sb, group, 0,
@@ -4486,34 +4482,29 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
 	/* Now try to see the extent can be merged to left and right */
 	node = rb_prev(new_node);
 	if (node) {
-		entry = rb_entry(node, struct ext4_free_data, node);
+		entry = rb_entry(node, struct ext4_free_data, efd_node);
 		if (can_merge(entry, new_entry)) {
-			new_entry->start_cluster = entry->start_cluster;
-			new_entry->count += entry->count;
+			new_entry->efd_start_cluster = entry->efd_start_cluster;
+			new_entry->efd_count += entry->efd_count;
 			rb_erase(node, &(db->bb_free_root));
-			spin_lock(&sbi->s_md_lock);
-			list_del(&entry->list);
-			spin_unlock(&sbi->s_md_lock);
-			kmem_cache_free(ext4_free_ext_cachep, entry);
+			ext4_journal_callback_del(handle, &entry->efd_jce);
+			kmem_cache_free(ext4_free_data_cachep, entry);
 		}
 	}
 
 	node = rb_next(new_node);
 	if (node) {
-		entry = rb_entry(node, struct ext4_free_data, node);
+		entry = rb_entry(node, struct ext4_free_data, efd_node);
 		if (can_merge(new_entry, entry)) {
-			new_entry->count += entry->count;
+			new_entry->efd_count += entry->efd_count;
 			rb_erase(node, &(db->bb_free_root));
-			spin_lock(&sbi->s_md_lock);
-			list_del(&entry->list);
-			spin_unlock(&sbi->s_md_lock);
-			kmem_cache_free(ext4_free_ext_cachep, entry);
+			ext4_journal_callback_del(handle, &entry->efd_jce);
+			kmem_cache_free(ext4_free_data_cachep, entry);
 		}
 	}
 	/* Add the extent to transaction's private list */
-	spin_lock(&sbi->s_md_lock);
-	list_add(&new_entry->list, &handle->h_transaction->t_private_list);
-	spin_unlock(&sbi->s_md_lock);
+	ext4_journal_callback_add(handle, ext4_free_data_callback,
+				  &new_entry->efd_jce);
 	return 0;
 }
 
@@ -4691,15 +4682,15 @@ do_more:
 		 * blocks being freed are metadata. these blocks shouldn't
 		 * be used until this transaction is committed
 		 */
-		new_entry = kmem_cache_alloc(ext4_free_ext_cachep, GFP_NOFS);
+		new_entry = kmem_cache_alloc(ext4_free_data_cachep, GFP_NOFS);
 		if (!new_entry) {
 			err = -ENOMEM;
 			goto error_return;
 		}
-		new_entry->start_cluster = bit;
-		new_entry->group  = block_group;
-		new_entry->count = count_clusters;
-		new_entry->t_tid = handle->h_transaction->t_tid;
+		new_entry->efd_start_cluster = bit;
+		new_entry->efd_group = block_group;
+		new_entry->efd_count = count_clusters;
+		new_entry->efd_tid = handle->h_transaction->t_tid;
 
 		ext4_lock_group(sb, block_group);
 		mb_clear_bits(bitmap_bh->b_data, bit, count_clusters);
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 47705f3..7128f46 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -96,21 +96,23 @@ extern u8 mb_enable_debug;
 
 
 struct ext4_free_data {
-	/* this links the free block information from group_info */
-	struct rb_node node;
+	/* MUST be the first member */
+	struct ext4_journal_cb_entry	efd_jce;
+
+	/* ext4_free_data private data starts from here */
 
-	/* this links the free block information from ext4_sb_info */
-	struct list_head list;
+	/* this links the free block information from group_info */
+	struct rb_node			efd_node;
 
 	/* group which free block extent belongs */
-	ext4_group_t group;
+	ext4_group_t			efd_group;
 
 	/* free block extent */
-	ext4_grpblk_t start_cluster;
-	ext4_grpblk_t count;
+	ext4_grpblk_t			efd_start_cluster;
+	ext4_grpblk_t			efd_count;
 
 	/* transaction which freed this extent */
-	tid_t	t_tid;
+	tid_t				efd_tid;
 };
 
 struct ext4_prealloc_space {
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9953d80..f5da954 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -431,6 +431,22 @@ static int block_device_ejected(struct super_block *sb)
 	return bdi->dev == NULL;
 }
 
+static void ext4_journal_commit_callback(journal_t *journal, transaction_t *txn)
+{
+	struct super_block		*sb = journal->j_private;
+	struct ext4_sb_info		*sbi = EXT4_SB(sb);
+	int				error = is_journal_aborted(journal);
+	struct ext4_journal_cb_entry	*jce, *tmp;
+
+	spin_lock(&sbi->s_md_lock);
+	list_for_each_entry_safe(jce, tmp, &txn->t_private_list, jce_list) {
+		list_del_init(&jce->jce_list);
+		spin_unlock(&sbi->s_md_lock);
+		jce->jce_func(sb, jce, error);
+		spin_lock(&sbi->s_md_lock);
+	}
+	spin_unlock(&sbi->s_md_lock);
+}
 
 /* Deal with the reporting of failure conditions on a filesystem such as
  * inconsistencies detected or read IO failures.
@@ -3698,6 +3714,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	}
 	set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
 
+	sbi->s_journal->j_commit_callback = ext4_journal_commit_callback;
+
 	/*
 	 * The journal may have updated the bg summary counts, so we
 	 * need to update the global counters.
-- 
1.7.7

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