ext4: provide wrappers for transaction reservation calls

Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4_jbd2.c

@@ -38,31 +38,43 @@ static void ext4_put_nojournal(handle_t *handle)
 /*
  * Wrappers for jbd2_journal_start/end.
  */
-handle_t *__ext4_journal_start_sb(struct super_block *sb, unsigned int line,
+static int ext4_journal_check_start(struct super_block *sb)
-				  int type, int nblocks)
 {
 	journal_t *journal;
 
 	might_sleep();
-
-	trace_ext4_journal_start(sb, nblocks, _RET_IP_);
 	if (sb->s_flags & MS_RDONLY)
-		return ERR_PTR(-EROFS);
+		return -EROFS;
-
 	WARN_ON(sb->s_writers.frozen == SB_FREEZE_COMPLETE);
 	journal = EXT4_SB(sb)->s_journal;
-	if (!journal)
-		return ext4_get_nojournal();
 	/*
 	 * Special case here: if the journal has aborted behind our
 	 * backs (eg. EIO in the commit thread), then we still need to
 	 * take the FS itself readonly cleanly.
 	 */
-	if (is_journal_aborted(journal)) {
+	if (journal && is_journal_aborted(journal)) {
 		ext4_abort(sb, "Detected aborted journal");
-		return ERR_PTR(-EROFS);
+		return -EROFS;
 	}
-	return jbd2__journal_start(journal, nblocks, 0, GFP_NOFS, type, line);
+	return 0;
+}
+
+handle_t *__ext4_journal_start_sb(struct super_block *sb, unsigned int line,
+				  int type, int blocks, int rsv_blocks)
+{
+	journal_t *journal;
+	int err;
+
+	trace_ext4_journal_start(sb, blocks, rsv_blocks, _RET_IP_);
+	err = ext4_journal_check_start(sb);
+	if (err < 0)
+		return ERR_PTR(err);
+
+	journal = EXT4_SB(sb)->s_journal;
+	if (!journal)
+		return ext4_get_nojournal();
+	return jbd2__journal_start(journal, blocks, rsv_blocks, GFP_NOFS,
+				   type, line);
 }
 
 int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle)
@@ -86,6 +98,30 @@ int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle)
 	return err;
 }
 
+handle_t *__ext4_journal_start_reserved(handle_t *handle, unsigned int line,
+					int type)
+{
+	struct super_block *sb;
+	int err;
+
+	if (!ext4_handle_valid(handle))
+		return ext4_get_nojournal();
+
+	sb = handle->h_journal->j_private;
+	trace_ext4_journal_start_reserved(sb, handle->h_buffer_credits,
+					  _RET_IP_);
+	err = ext4_journal_check_start(sb);
+	if (err < 0) {
+		jbd2_journal_free_reserved(handle);
+		return ERR_PTR(err);
+	}
+
+	err = jbd2_journal_start_reserved(handle, type, line);
+	if (err < 0)
+		return ERR_PTR(err);
+	return handle;
+}
+
 void ext4_journal_abort_handle(const char *caller, unsigned int line,
 			       const char *err_fn, struct buffer_head *bh,
 			       handle_t *handle, int err)

fs/ext4/ext4_jbd2.h

@@ -265,7 +265,7 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
 	__ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb))
 
 handle_t *__ext4_journal_start_sb(struct super_block *sb, unsigned int line,
-				  int type, int nblocks);
+				  int type, int blocks, int rsv_blocks);
 int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle);
 
 #define EXT4_NOJOURNAL_MAX_REF_COUNT ((unsigned long) 4096)
@@ -300,21 +300,37 @@ static inline int ext4_handle_has_enough_credits(handle_t *handle, int needed)
 }
 
 #define ext4_journal_start_sb(sb, type, nblocks)			\
-	__ext4_journal_start_sb((sb), __LINE__, (type), (nblocks))
+	__ext4_journal_start_sb((sb), __LINE__, (type), (nblocks), 0)
 
 #define ext4_journal_start(inode, type, nblocks)			\
-	__ext4_journal_start((inode), __LINE__, (type), (nblocks))
+	__ext4_journal_start((inode), __LINE__, (type), (nblocks), 0)
+
+#define ext4_journal_start_with_reserve(inode, type, blocks, rsv_blocks) \
+	__ext4_journal_start((inode), __LINE__, (type), (blocks), (rsv_blocks))
 
 static inline handle_t *__ext4_journal_start(struct inode *inode,
 					     unsigned int line, int type,
-					     int nblocks)
+					     int blocks, int rsv_blocks)
 {
-	return __ext4_journal_start_sb(inode->i_sb, line, type, nblocks);
+	return __ext4_journal_start_sb(inode->i_sb, line, type, blocks,
+				       rsv_blocks);
 }
 
 #define ext4_journal_stop(handle) \
 	__ext4_journal_stop(__func__, __LINE__, (handle))
 
+#define ext4_journal_start_reserve(handle, type) \
+	__ext4_journal_start_reserved((handle), __LINE__, (type))
+
+handle_t *__ext4_journal_start_reserved(handle_t *handle, unsigned int line,
+					int type);
+
+static inline void ext4_journal_free_reserved(handle_t *handle)
+{
+	if (ext4_handle_valid(handle))
+		jbd2_journal_free_reserved(handle);
+}
+
 static inline handle_t *ext4_journal_current_handle(void)
 {
 	return journal_current_handle();

fs/ext4/ialloc.c

@@ -747,7 +747,8 @@ repeat_in_this_group:
 		if (!handle) {
 			BUG_ON(nblocks <= 0);
 			handle = __ext4_journal_start_sb(dir->i_sb, line_no,
-							 handle_type, nblocks);
+							 handle_type, nblocks,
+							 0);
 			if (IS_ERR(handle)) {
 				err = PTR_ERR(handle);
 				ext4_std_error(sb, err);

include/trace/events/ext4.h

@@ -1640,25 +1640,50 @@ TRACE_EVENT(ext4_load_inode,
 );
 
 TRACE_EVENT(ext4_journal_start,
-	TP_PROTO(struct super_block *sb, int nblocks, unsigned long IP),
+	TP_PROTO(struct super_block *sb, int blocks, int rsv_blocks,
+		 unsigned long IP),
 
-	TP_ARGS(sb, nblocks, IP),
+	TP_ARGS(sb, blocks, rsv_blocks, IP),
 
 	TP_STRUCT__entry(
 		__field(	dev_t,	dev			)
 		__field(unsigned long,	ip			)
-		__field(	int,	nblocks			)
+		__field(	  int,	blocks			)
+		__field(	  int,	rsv_blocks		)
 	),
 
 	TP_fast_assign(
-		__entry->dev	 = sb->s_dev;
+		__entry->dev		 = sb->s_dev;
-		__entry->ip	 = IP;
+		__entry->ip		 = IP;
-		__entry->nblocks = nblocks;
+		__entry->blocks		 = blocks;
+		__entry->rsv_blocks	 = rsv_blocks;
 	),
 
-	TP_printk("dev %d,%d nblocks %d caller %pF",
+	TP_printk("dev %d,%d blocks, %d rsv_blocks, %d caller %pF",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
-		  __entry->nblocks, (void *)__entry->ip)
+		  __entry->blocks, __entry->rsv_blocks, (void *)__entry->ip)
+);
+
+TRACE_EVENT(ext4_journal_start_reserved,
+	TP_PROTO(struct super_block *sb, int blocks, unsigned long IP),
+
+	TP_ARGS(sb, blocks, IP),
+
+	TP_STRUCT__entry(
+		__field(	dev_t,	dev			)
+		__field(unsigned long,	ip			)
+		__field(	  int,	blocks			)
+	),
+
+	TP_fast_assign(
+		__entry->dev		 = sb->s_dev;
+		__entry->ip		 = IP;
+		__entry->blocks		 = blocks;
+	),
+
+	TP_printk("dev %d,%d blocks, %d caller %pF",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->blocks, (void *)__entry->ip)
 );
 
 DECLARE_EVENT_CLASS(ext4__trim,