[PATCH 9/9] ext4: Use mmb infrastructure for inode buffer writeout

[Jan Kara <jack@suse.cz>]

Use mmb inode buffer writeout infrastructure to reliably write out
inode's inode table block on fsync(2) in nojournal mode (from
ext4_sync_parent() and ext4_fsync_nojournal()). This significantly
simplifies the code as we don't have to explicitely handle inode buffer
writeback in ext4_write_inode() and thus we can also remove
sync_inode_metadata() calls from ext4_sync_parent() and
ext4_write_inode() call from ext4_fsync_nojournal().

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/ext4_jbd2.c |  2 +-
 fs/ext4/ext4_jbd2.h |  2 ++
 fs/ext4/fsync.c     | 12 ------------
 fs/ext4/inode.c     | 24 +++++-------------------
 4 files changed, 8 insertions(+), 32 deletions(-)

diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index 74f05bd0cdde..6bbaf72108fd 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -350,7 +350,7 @@ int __ext4_journal_get_create_access(const char *where, unsigned int line,
 	return 0;
 }
 
-static void ext4_inode_attach_mmb(struct inode *inode)
+void ext4_inode_attach_mmb(struct inode *inode)
 {
 	struct mapping_metadata_bhs *mmb;
 
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 63d17c5201b5..2a01b8279c88 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -122,6 +122,8 @@
 #define EXT4_HT_EXT_CONVERT     11
 #define EXT4_HT_MAX             12
 
+void ext4_inode_attach_mmb(struct inode *inode);
+
 int
 ext4_mark_iloc_dirty(handle_t *handle,
 		     struct inode *inode,
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index e25d365e1179..af84489e57c6 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -75,9 +75,6 @@ static int ext4_sync_parent(struct inode *inode)
 			if (ret)
 				break;
 		}
-		ret = sync_inode_metadata(inode, 1);
-		if (ret)
-			break;
 	}
 	dput(dentry);
 	return ret;
@@ -87,10 +84,6 @@ static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
 				int datasync, bool *needs_barrier)
 {
 	struct inode *inode = file->f_inode;
-	struct writeback_control wbc = {
-		.sync_mode = WB_SYNC_ALL,
-		.nr_to_write = 0,
-	};
 	int ret;
 
 	ret = mmb_fsync_noflush(file, EXT4_I(inode)->i_metadata_bhs,
@@ -98,11 +91,6 @@ static int ext4_fsync_nojournal(struct file *file, loff_t start, loff_t end,
 	if (ret)
 		return ret;
 
-	/* Force writeout of inode table buffer to disk */
-	ret = ext4_write_inode(inode, &wbc);
-	if (ret)
-		return ret;
-
 	ret = ext4_sync_parent(inode);
 
 	if (test_opt(inode->i_sb, BARRIER))
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3e66e9510909..09506b4de1b2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5786,24 +5786,6 @@ int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
 
 		err = ext4_fc_commit(EXT4_SB(inode->i_sb)->s_journal,
 						EXT4_I(inode)->i_sync_tid);
-	} else {
-		struct ext4_iloc iloc;
-
-		err = __ext4_get_inode_loc_noinmem(inode, &iloc);
-		if (err)
-			return err;
-		/*
-		 * sync(2) will flush the whole buffer cache. No need to do
-		 * it here separately for each inode.
-		 */
-		if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
-			sync_dirty_buffer(iloc.bh);
-		if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
-			ext4_error_inode_block(inode, iloc.bh->b_blocknr, EIO,
-					       "IO error syncing inode");
-			err = -EIO;
-		}
-		brelse(iloc.bh);
 	}
 	return err;
 }
@@ -6348,7 +6330,11 @@ int ext4_mark_iloc_dirty(handle_t *handle,
 
 	/* the do_update_inode consumes one bh->b_count */
 	get_bh(iloc->bh);
-
+	if (!ext4_handle_valid(handle)) {
+		if (!EXT4_I(inode)->i_metadata_bhs)
+			ext4_inode_attach_mmb(inode);
+		EXT4_I(inode)->i_metadata_bhs->inode_blk = iloc->bh->b_blocknr;
+	}
 	/* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
 	err = ext4_do_update_inode(handle, inode, iloc);
 	put_bh(iloc->bh);
-- 
2.51.0