linux-kernel - [PATCH 1/1 linux-next] fs/affs/file.c: fix direct IO writes beyond EOF

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Message-Id: <1420838383-6638-1-git-send-email-fabf@skynet.be>
Date:	Fri,  9 Jan 2015 22:19:43 +0100
From:	Fabian Frederick <fabf@...net.be>
To:	linux-kernel@...r.kernel.org
Cc:	Fabian Frederick <fabf@...net.be>, Jan Kara <jack@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 1/1 linux-next] fs/affs/file.c: fix direct IO writes beyond EOF

Use the same fallback to normal IO in case of write
operations beyond EOF as fat direct IO. This patch fixes

fsx file -d -Z -r 4096 -w 4096

Report:
129(129 mod 256): TRUNCATE DOWN from 0x3ff01 to 0xb3f6
130(130 mod 256): WRITE    0x22000 thru 0x2dfff (0xc000 bytes) HOLE

Thanks to Jan for helping me on this problem.

Cc: Jan Kara <jack@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@...net.be>
---
Ideal solution suggested by Jan Kara would be to use cont_write_begin but
 affs direct_IO shouldn't be used a lot anyway...

 fs/affs/file.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/affs/file.c b/fs/affs/file.c
index 7e83ba2..d2468bf 100644
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -398,6 +398,13 @@ affs_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
 	size_t count = iov_iter_count(iter);
 	ssize_t ret;
 
+	if (rw == WRITE) {
+		loff_t size = offset + count;
+
+		if (AFFS_I(inode)->mmu_private < size)
+			return 0;
+	}
+
 	ret = blockdev_direct_IO(rw, iocb, inode, iter, offset, affs_get_block);
 	if (ret < 0 && (rw & WRITE))
 		affs_write_failed(mapping, offset + count);
-- 
2.1.0

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