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From: Matthew Bobrowski <mbobrowski@mbobrowski.org>
To: tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca
Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	riteshh@linux.ibm.com
Subject: [PATCH v7 02/11] ext4: update direct I/O read lock pattern for IOCB_NOWAIT
Date: Tue, 5 Nov 2019 22:59:22 +1100
Message-ID: <c5d5e759f91747359fbd2c6f9a36240cf75ad79f.1572949325.git.mbobrowski@mbobrowski.org> (raw)
In-Reply-To: <cover.1572949325.git.mbobrowski@mbobrowski.org>

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>
---
 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 e4b0722717b3..f33fa86fff67 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3881,7 +3881,13 @@ 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)
-- 
2.20.1


  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-05 11:58 [PATCH v7 00/11] ext4: port direct I/O to iomap infrastructure Matthew Bobrowski
2019-11-05 11:58 ` [PATCH v7 01/11] ext4: reorder map.m_flags checks within ext4_iomap_begin() Matthew Bobrowski
2019-11-05 11:59 ` Matthew Bobrowski [this message]
2019-11-05 11:59 ` [PATCH v7 03/11] ext4: iomap that extends beyond EOF should be marked dirty Matthew Bobrowski
2019-11-05 11:59 ` [PATCH v7 04/11] ext4: move set iomap routines into a separate helper ext4_set_iomap() Matthew Bobrowski
2019-11-05 12:00 ` [PATCH v7 05/11] ext4: split IOMAP_WRITE branch in ext4_iomap_begin() into helper Matthew Bobrowski
2019-11-05 12:01 ` [PATCH v7 07/11] ext4: introduce direct I/O read using iomap infrastructure Matthew Bobrowski
2019-11-05 12:01 ` [PATCH v7 08/11] ext4: move inode extension/truncate code out from ->iomap_end() callback Matthew Bobrowski
2019-11-05 15:49   ` Darrick J. Wong
2019-11-05 21:10     ` Matthew Bobrowski
2019-11-05 12:02 ` [PATCH v7 09/11] ext4: move inode extension check out from ext4_iomap_alloc() Matthew Bobrowski
2019-11-05 12:02 ` [PATCH v7 10/11] ext4: update ext4_sync_file() to not use __generic_file_fsync() Matthew Bobrowski
2019-11-05 12:02 ` [PATCH v7 11/11] ext4: introduce direct I/O write using iomap infrastructure Matthew Bobrowski
2019-11-05 13:59   ` Jan Kara
2019-11-05 20:32     ` Matthew Bobrowski
2019-11-05 20:53       ` Theodore Y. Ts'o
2019-11-05 21:00         ` Matthew Bobrowski
2019-11-06  0:59           ` Theodore Y. Ts'o
2019-11-05 16:28   ` Theodore Y. Ts'o
2019-11-05 20:57     ` Matthew Bobrowski
2019-11-05 12:03 ` [PATCH v7 06/11] ext4: introduce new callback for IOMAP_REPORT Matthew Bobrowski
2019-11-05 15:43   ` Darrick J. Wong

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