This is a note to let you know that I've just added the patch titled ext4: update direct I/O read lock pattern for IOCB_NOWAIT to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-update-direct-i-o-read-lock-pattern-for-iocb_no.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 80e10d2642bcc70b27f4d17a72209944904f6118 Author: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx> Date: Tue Nov 5 22:59:22 2019 +1100 ext4: update direct I/O read lock pattern for IOCB_NOWAIT [ Upstream commit 548feebec7e93e58b647dba70b3303dcb569c914 ] This patch updates the lock pattern in ext4_direct_IO_read() to not block on inode lock in cases of IOCB_NOWAIT direct I/O reads. The locking condition implemented here is similar to that of 942491c9e6d6 ("xfs: fix AIM7 regression"). Fixes: 16c54688592c ("ext4: Allow parallel DIO reads") Signed-off-by: Matthew Bobrowski <mbobrowski@xxxxxxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Reviewed-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/c5d5e759f91747359fbd2c6f9a36240cf75ad79f.1572949325.git.mbobrowski@xxxxxxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c2920cbfa3bf..a91b8404d3dc 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3796,7 +3796,13 @@ static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter) * writes & truncates and since we take care of writing back page cache, * we are protected against page writeback as well. */ - inode_lock_shared(inode); + if (iocb->ki_flags & IOCB_NOWAIT) { + if (!inode_trylock_shared(inode)) + return -EAGAIN; + } else { + inode_lock_shared(inode); + } + ret = filemap_write_and_wait_range(mapping, iocb->ki_pos, iocb->ki_pos + count - 1); if (ret)