From: Matthew Bobrowski mbobrowski@mbobrowski.org
[ 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@mbobrowski.org Reviewed-by: Jan Kara jack@suse.cz Reviewed-by: Ritesh Harjani riteshh@linux.ibm.com Link: https://lore.kernel.org/r/c5d5e759f91747359fbd2c6f9a36240cf75ad79f.157294932... Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Sasha Levin sashal@kernel.org --- 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 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)