ext4: Adjust ext4_da_writepages() to write out larger contiguous chunks

(cherry picked from commit 55138e0bc29c0751e2152df9ad35deea542f29b3)

Work around problems in the writeback code to force out writebacks in
larger chunks than just 4mb, which is just too small.  This also works
around limitations in the ext4 block allocator, which can't allocate
more than 2048 blocks at a time.  So we need to defeat the round-robin
characteristics of the writeback code and try to write out as many
blocks in one inode before allowing the writeback code to move on to
another inode.  We add a a new per-filesystem tunable,
max_writeback_mb_bump, which caps this to a default of 128mb per
inode.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 48 insertions, 6 deletions

diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 718b0d9293ed..824979e60677 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -231,6 +231,7 @@ TRACE_EVENT(ext4_da_writepages,
 		__field(	char,	for_reclaim		)
 		__field(	char,	for_writepages		)
 		__field(	char,	range_cyclic		)
+		__field(       pgoff_t,	writeback_index		)
 	),
 
 	TP_fast_assign(
@@ -245,14 +246,51 @@ TRACE_EVENT(ext4_da_writepages,
 		__entry->for_reclaim	= wbc->for_reclaim;
 		__entry->for_writepages	= wbc->for_writepages;
 		__entry->range_cyclic	= wbc->range_cyclic;
+		__entry->writeback_index = inode->i_mapping->writeback_index;
 	),
 
-	TP_printk("dev %s ino %lu nr_t_write %ld pages_skipped %ld range_start %llu range_end %llu nonblocking %d for_kupdate %d for_reclaim %d for_writepages %d range_cyclic %d",
-		  jbd2_dev_to_name(__entry->dev), __entry->ino, __entry->nr_to_write,
+	TP_printk("dev %s ino %lu nr_to_write %ld pages_skipped %ld range_start %llu range_end %llu nonblocking %d for_kupdate %d for_reclaim %d for_writepages %d range_cyclic %d writeback_index %lu",
+		  jbd2_dev_to_name(__entry->dev),
+		  (unsigned long) __entry->ino, __entry->nr_to_write,
 		  __entry->pages_skipped, __entry->range_start,
 		  __entry->range_end, __entry->nonblocking,
 		  __entry->for_kupdate, __entry->for_reclaim,
-		  __entry->for_writepages, __entry->range_cyclic)
+		  __entry->for_writepages, __entry->range_cyclic,
+		  (unsigned long) __entry->writeback_index)
+);
+
+TRACE_EVENT(ext4_da_write_pages,
+	TP_PROTO(struct inode *inode, struct mpage_da_data *mpd),
+
+	TP_ARGS(inode, mpd),
+
+	TP_STRUCT__entry(
+		__field(	dev_t,	dev			)
+		__field(	ino_t,	ino			)
+		__field(	__u64,	b_blocknr		)
+		__field(	__u32,	b_size			)
+		__field(	__u32,	b_state			)
+		__field(	unsigned long,	first_page	)
+		__field(	int,	io_done			)
+		__field(	int,	pages_written		)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= inode->i_sb->s_dev;
+		__entry->ino		= inode->i_ino;
+		__entry->b_blocknr	= mpd->b_blocknr;
+		__entry->b_size		= mpd->b_size;
+		__entry->b_state	= mpd->b_state;
+		__entry->first_page	= mpd->first_page;
+		__entry->io_done	= mpd->io_done;
+		__entry->pages_written	= mpd->pages_written;
+	),
+
+	TP_printk("dev %s ino %lu b_blocknr %llu b_size %u b_state 0x%04x first_page %lu io_done %d pages_written %d",
+		  jbd2_dev_to_name(__entry->dev), (unsigned long) __entry->ino,
+		  __entry->b_blocknr, __entry->b_size,
+		  __entry->b_state, __entry->first_page,
+		  __entry->io_done, __entry->pages_written)
 );
 
 TRACE_EVENT(ext4_da_writepages_result,
@@ -270,6 +308,7 @@ TRACE_EVENT(ext4_da_writepages_result,
 		__field(	char,	encountered_congestion	)
 		__field(	char,	more_io			)	
 		__field(	char,	no_nrwrite_index_update )
+		__field(       pgoff_t,	writeback_index		)
 	),
 
 	TP_fast_assign(
@@ -281,13 +320,16 @@ TRACE_EVENT(ext4_da_writepages_result,
 		__entry->encountered_congestion	= wbc->encountered_congestion;
 		__entry->more_io	= wbc->more_io;
 		__entry->no_nrwrite_index_update = wbc->no_nrwrite_index_update;
+		__entry->writeback_index = inode->i_mapping->writeback_index;
 	),
 
-	TP_printk("dev %s ino %lu ret %d pages_written %d pages_skipped %ld congestion %d more_io %d no_nrwrite_index_update %d",
-		  jbd2_dev_to_name(__entry->dev), __entry->ino, __entry->ret,
+	TP_printk("dev %s ino %lu ret %d pages_written %d pages_skipped %ld congestion %d more_io %d no_nrwrite_index_update %d writeback_index %lu",
+		  jbd2_dev_to_name(__entry->dev),
+		  (unsigned long) __entry->ino, __entry->ret,
 		  __entry->pages_written, __entry->pages_skipped,
 		  __entry->encountered_congestion, __entry->more_io,
-		  __entry->no_nrwrite_index_update)
+		  __entry->no_nrwrite_index_update,
+		  (unsigned long) __entry->writeback_index)
 );
 
 TRACE_EVENT(ext4_da_write_begin,