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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, Denis Kirjanov <kda@linux-powerpc.org>,
        "Chao Yu" <yuchao0@huawei.com>, "Jan Kara" <jack@suse.cz>
Date:   Fri, 24 Apr 2020 00:04:00 +0100
Message-ID: <lsq.1587683028.17394596@decadent.org.uk>
Subject: [PATCH 3.16 013/245] quota: fix wrong condition in
 is_quota_modification()
In-Reply-To: <lsq.1587683027.831233700@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Chao Yu <yuchao0@huawei.com>

commit 6565c182094f69e4ffdece337d395eb7ec760efc upstream.

Quoted from
commit 3da40c7b0898 ("ext4: only call ext4_truncate when size <= isize")

" At LSF we decided that if we truncate up from isize we shouldn't trim
  fallocated blocks that were fallocated with KEEP_SIZE and are past the
 new i_size.  This patch fixes ext4 to do this. "

And generic/092 of fstest have covered this case for long time, however
is_quota_modification() didn't adjust based on that rule, so that in
below condition, we will lose to quota block change:
- fallocate blocks beyond EOF
- remount
- truncate(file_path, file_size)

Fix it.

Link: https://lore.kernel.org/r/20190911093650.35329-1-yuchao0@huawei.com
Fixes: 3da40c7b0898 ("ext4: only call ext4_truncate when size <= isize")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 include/linux/quotaops.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -21,7 +21,7 @@ static inline struct quota_info *sb_dqop
 /* i_mutex must being held */
 static inline bool is_quota_modification(struct inode *inode, struct iattr *ia)
 {
-	return (ia->ia_valid & ATTR_SIZE && ia->ia_size != inode->i_size) ||
+	return (ia->ia_valid & ATTR_SIZE) ||
 		(ia->ia_valid & ATTR_UID && !uid_eq(ia->ia_uid, inode->i_uid)) ||
 		(ia->ia_valid & ATTR_GID && !gid_eq(ia->ia_gid, inode->i_gid));
 }