From 109811c20fb8ec46e2ed01750214a32a9163d164 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 8 Mar 2016 23:36:46 -0500 Subject: ext4: simplify io_end handling for AIO DIO When mapping blocks for direct IO, we allocate io_end structure before mapping blocks and store pointer to it in the inode. This creates a requirement that any AIO DIO using io_end must be protected by i_mutex. This created problems in the past with dioread_nolock mode which was corrupting io_end pointers. Also io_end is allocated unnecessarily in case where we don't need to convert any extents (which is a common case for example when overwriting file). We fix the problem by allocating io_end only once we return unwritten extent from block mapping function for AIO DIO (so we can save some pointless io_end allocations) and we pass pointer to it in bh->b_private which generic DIO code later passes to our end IO callback. That way we remove any need for global pointer to io_end structure and thus fix the races. The downside of this change is that the checking for unwritten IO in flight in ext4_extents_can_be_merged() is more racy since we now increment i_unwritten / set EXT4_STATE_DIO_UNWRITTEN only after dropping i_data_sem. However the check has been racy already before because ext4_writepages() already increment i_unwritten after dropping i_data_sem and reserved blocks save us from hitting ENOSPC in the worst case. Signed-off-by: Jan Kara --- fs/ext4/ext4.h | 10 ---------- 1 file changed, 10 deletions(-) (limited to 'fs/ext4/ext4.h') diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index d60db18edb4a..9f3156c38b16 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1513,16 +1513,6 @@ static inline void ext4_set_io_unwritten_flag(struct inode *inode, } } -static inline ext4_io_end_t *ext4_inode_aio(struct inode *inode) -{ - return inode->i_private; -} - -static inline void ext4_inode_aio_set(struct inode *inode, ext4_io_end_t *io) -{ - inode->i_private = io; -} - /* * Inode dynamic state flags */ -- cgit v1.2.3-55-g7522