blob: e43c639db35750a3601598933b0b883756a7ec82 [file] [log] [blame]
From f021ac812e5cfcc6effba953c0baddc3a90b5779 Mon Sep 17 00:00:00 2001
From: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Date: Tue, 5 Nov 2019 22:59:22 +1100
Subject: [PATCH] ext4: update direct I/O read lock pattern for IOCB_NOWAIT
commit 548feebec7e93e58b647dba70b3303dcb569c914 upstream.
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.1572949325.git.mbobrowski@mbobrowski.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0ee59a59e225..270e147d1392 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3872,7 +3872,13 @@ 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)
--
2.7.4