Commit 548feebe authored Nov 05, 2019 by Matthew Bobrowski Committed by Theodore Ts'o Nov 05, 2019

ext4: update direct I/O read lock pattern for IOCB_NOWAIT



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 942491c9
("xfs: fix AIM7 regression").

Fixes: 16c54688 ("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>

parent 53e5cca5

fs/ext4/inode.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -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.
		*/
		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)

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