From 9436aabf04a8e1591a03ee9b9163789fc06b9edd Mon Sep 17 00:00:00 2001 From: Matthew Bobrowski Date: Tue, 5 Nov 2019 22:59:22 +1100 Subject: [PATCH] ext4: update direct I/O read lock pattern for IOCB_NOWAIT BugLink: https://bugs.launchpad.net/bugs/1860602 [ 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 Reviewed-by: Jan Kara Reviewed-by: Ritesh Harjani Link: https://lore.kernel.org/r/c5d5e759f91747359fbd2c6f9a36240cf75ad79f.1572949325.git.mbobrowski@mbobrowski.org Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin Signed-off-by: Kamal Mostafa Signed-off-by: Khalid Elmously --- fs/ext4/inode.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index add419e4d57a..d9ebde8f022d 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3842,7 +3842,13 @@ 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) -- 2.39.2