diff options
| author |   Ritesh Harjani <riteshh@linux.ibm.com> | 2019-12-12 11:25:57 +0530 |
|---|---|---|
| committer |   Theodore Ts'o <tytso@mit.edu> | 2019-12-22 23:57:27 -0500 |
| commit | bc6385dab125d20870f0eb9ca9e589f43abb3f56 (patch) | |
| tree | cd540e75d89db53d020513cfda559ef5fb5ed294 /fs/ext4 | |
| parent | ext4: Start with shared i_rwsem in case of DIO instead of exclusive (diff) | |
| download | linux-dev-bc6385dab125d20870f0eb9ca9e589f43abb3f56.tar.xz linux-dev-bc6385dab125d20870f0eb9ca9e589f43abb3f56.zip | |
ext4: Move to shared i_rwsem even without dioread_nolock mount opt
We were using shared locking only in case of dioread_nolock mount option in case
of DIO overwrites. This mount condition is not needed anymore with current code,
since:-
1. No race between buffered writes & DIO overwrites. Since buffIO writes takes
exclusive lock & DIO overwrites will take shared locking. Also DIO path will
make sure to flush and wait for any dirty page cache data.
2. No race between buffered reads & DIO overwrites, since there is no block
allocation that is possible with DIO overwrites. So no stale data exposure
should happen. Same is the case between DIO reads & DIO overwrites.
3. Also other paths like truncate is protected, since we wait there for any DIO
in flight to be over.
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20191212055557.11151-4-riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/file.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 1da49dffa3df..9c2711bce0f9 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -392,8 +392,8 @@ static const struct iomap_dio_ops ext4_dio_write_ops = { * - For extending writes case we don't take the shared lock, since it requires * updating inode i_disksize and/or orphan handling with exclusive lock. * - * - shared locking will only be true mostly with overwrites in dioread_nolock - * mode. Otherwise we will switch to exclusive i_rwsem lock. + * - shared locking will only be true mostly with overwrites. Otherwise we will + * switch to exclusive i_rwsem lock. */ static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from, bool *ilock_shared, bool *extend) @@ -415,14 +415,11 @@ restart: *extend = true; /* * Determine whether the IO operation will overwrite allocated - * and initialized blocks. If so, check to see whether it is - * possible to take the dioread_nolock path. - * + * and initialized blocks. * We need exclusive i_rwsem for changing security info * in file_modified(). */ if (*ilock_shared && (!IS_NOSEC(inode) || *extend || - !ext4_should_dioread_nolock(inode) || !ext4_overwrite_io(inode, offset, count))) { inode_unlock_shared(inode); *ilock_shared = false; |