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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "=?UTF-8?q?Ernesto=20A . =20Fern=C3=A1ndez?=" 
        <ernesto.mnd.fernandez@gmail.com>,
        Vyacheslav Dubeyko <slava@dubeyko.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 175/306] hfs: fix return value of hfs_get_block()
Date:   Wed, 27 Nov 2019 21:30:25 +0100
Message-Id: <20191127203128.147157857@linuxfoundation.org>
In-Reply-To: <20191127203114.766709977@linuxfoundation.org>
References: <20191127203114.766709977@linuxfoundation.org>
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From: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>

[ Upstream commit 1267a07be5ebbff2d2739290f3d043ae137c15b4 ]

Direct writes to empty inodes fail with EIO.  The generic direct-io code
is in part to blame (a patch has been submitted as "direct-io: allow
direct writes to empty inodes"), but hfs is worse affected than the other
filesystems because the fallback to buffered I/O doesn't happen.

The problem is the return value of hfs_get_block() when called with
!create.  Change it to be more consistent with the other modules.

Link: http://lkml.kernel.org/r/4538ab8c35ea37338490525f0f24cbc37227528c.1539195310.git.ernesto.mnd.fernandez@gmail.com
Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Reviewed-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/hfs/extent.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/hfs/extent.c b/fs/hfs/extent.c
index 0c638c6121526..5f1ff97a3b987 100644
--- a/fs/hfs/extent.c
+++ b/fs/hfs/extent.c
@@ -345,7 +345,9 @@ int hfs_get_block(struct inode *inode, sector_t block,
 	ablock = (u32)block / HFS_SB(sb)->fs_div;
 
 	if (block >= HFS_I(inode)->fs_blocks) {
-		if (block > HFS_I(inode)->fs_blocks || !create)
+		if (!create)
+			return 0;
+		if (block > HFS_I(inode)->fs_blocks)
 			return -EIO;
 		if (ablock >= HFS_I(inode)->alloc_blocks) {
 			res = hfs_extend_file(inode);
-- 
2.20.1