linux-kernel - [PATCH] quota: fix wrong condition in is_quota

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Date:   Wed, 11 Sep 2019 17:36:50 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <jack@...e.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <chao@...nel.org>, Chao Yu <yuchao0@...wei.com>
Subject: [PATCH] quota: fix wrong condition in is_quota_modification()

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.

Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
 include/linux/quotaops.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index dc905a4ff8d7..bd30acad3a7f 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -22,7 +22,7 @@ static inline struct quota_info *sb_dqopt(struct super_block *sb)
 /* 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_size <= inode->i_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));
 }
-- 
2.18.0.rc1