From 7dd6dc4704480d9d07113c7218649cd056ea8508 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 15 Mar 2016 15:25:02 +0100
Subject: [PATCH 4/4] ext4: Do not ask jbd2 to write data for delalloc buffers

Currently we ask jbd2 to write all dirty allocated buffers before
committing a transaction when doing writeback of delay allocated blocks.
However this is unnecessary since we move all pages to writeback state
before dropping a transaction handle and then submit all the necessary
IO. We still need the transaction commit to wait for all the outstanding
writeback before flushing disk caches during transaction commit to avoid
data exposure issues though. Use the new jbd2 capability and ask it to
only wait for outstanding writeback during transaction commit when
writing back data in ext4_writepages().

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/ext4.h        |  3 +++
 fs/ext4/ext4_jbd2.h   | 12 +++++++++++-
 fs/ext4/inode.c       | 10 +++++++---
 fs/ext4/move_extent.c |  2 +-
 fs/jbd2/transaction.c |  4 ++--
 5 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index bc4910bce4ff..a095e833a6c0 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -561,6 +561,9 @@ enum {
 #define EXT4_GET_BLOCKS_ZERO			0x0200
 #define EXT4_GET_BLOCKS_CREATE_ZERO		(EXT4_GET_BLOCKS_CREATE |\
 					EXT4_GET_BLOCKS_ZERO)
+	/* Caller will submit data before dropping transaction handle. This
+	 * allows jbd2 to avoid submitting data before commit. */
+#define EXT4_GET_BLOCKS_IO_SUBMIT		0x0400
 
 /*
  * The bit position of these flags must not overlap with any of the
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index f1c940b38b30..09c1ef38cbe6 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -359,7 +359,8 @@ static inline int ext4_journal_force_commit(journal_t *journal)
 	return 0;
 }
 
-static inline int ext4_jbd2_file_inode(handle_t *handle, struct inode *inode)
+static inline int ext4_jbd2_inode_add_write(handle_t *handle,
+					    struct inode *inode)
 {
 	if (ext4_handle_valid(handle))
 		return jbd2_journal_inode_add_write(handle,
@@ -367,6 +368,15 @@ static inline int ext4_jbd2_file_inode(handle_t *handle, struct inode *inode)
 	return 0;
 }
 
+static inline int ext4_jbd2_inode_add_wait(handle_t *handle,
+					   struct inode *inode)
+{
+	if (ext4_handle_valid(handle))
+		return jbd2_journal_inode_add_wait(handle,
+						   EXT4_I(inode)->jinode);
+	return 0;
+}
+
 static inline void ext4_update_inode_fsync_trans(handle_t *handle,
 						 struct inode *inode,
 						 int datasync)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 173da9d467d1..01ecc67985bb 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -692,7 +692,10 @@ out_sem:
 		    !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
 		    !(flags & EXT4_GET_BLOCKS_ZERO) &&
 		    ext4_should_order_data(inode)) {
-			ret = ext4_jbd2_file_inode(handle, inode);
+			if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
+				ret = ext4_jbd2_inode_add_wait(handle, inode);
+			else
+				ret = ext4_jbd2_inode_add_write(handle, inode);
 			if (ret)
 				return ret;
 		}
@@ -2164,7 +2167,8 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
 	 * the data was copied into the page cache.
 	 */
 	get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
-			   EXT4_GET_BLOCKS_METADATA_NOFAIL;
+			   EXT4_GET_BLOCKS_METADATA_NOFAIL |
+			   EXT4_GET_BLOCKS_IO_SUBMIT;
 	dioread_nolock = ext4_should_dioread_nolock(inode);
 	if (dioread_nolock)
 		get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
@@ -3538,7 +3542,7 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 		err = 0;
 		mark_buffer_dirty(bh);
 		if (ext4_should_order_data(inode))
-			err = ext4_jbd2_file_inode(handle, inode);
+			err = ext4_jbd2_inode_add_write(handle, inode);
 	}
 
 unlock:
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index fb6f11709ae6..0ce9795c7404 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -390,7 +390,7 @@ data_copy:
 
 	/* Even in case of data=writeback it is reasonable to pin
 	 * inode to transaction, to prevent unexpected data loss */
-	*err = ext4_jbd2_file_inode(handle, orig_inode);
+	*err = ext4_jbd2_inode_add_write(handle, orig_inode);
 
 unlock_pages:
 	unlock_page(pagep[0]);
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 0fcbec79fc7e..903ad38443c8 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2504,14 +2504,14 @@ static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
 	 */
 	if ((jinode->i_transaction == transaction ||
 	    jinode->i_next_transaction == transaction) &&
-	    jinode->i_flags & flags == flags)
+	    (jinode->i_flags & flags) == flags)
 		return 0;
 
 	spin_lock(&journal->j_list_lock);
 
 	if ((jinode->i_transaction == transaction ||
 	    jinode->i_next_transaction == transaction) &&
-	    jinode->i_flags & flags == flags)
+	    (jinode->i_flags & flags) == flags)
 		goto done;
 
 	/*
-- 
2.6.2

