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author | Jan Kara <jack@suse.cz> | 2016-03-08 23:36:46 -0500 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2016-03-08 23:36:46 -0500 |
commit | 109811c20fb8ec46e2ed01750214a32a9163d164 (patch) | |
tree | 63284815eb0c1f0386a93b51cda92682d26ce02e /fs/ext4/ext4.h | |
parent | efe70c29511544b0468723fe92c1847b3b0ca046 (diff) | |
download | op-kernel-dev-109811c20fb8ec46e2ed01750214a32a9163d164.zip op-kernel-dev-109811c20fb8ec46e2ed01750214a32a9163d164.tar.gz |
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 <jack@suse.cz>
Diffstat (limited to 'fs/ext4/ext4.h')
-rw-r--r-- | fs/ext4/ext4.h | 10 |
1 files changed, 0 insertions, 10 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index d60db18..9f3156c 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 */ |