From: Xue jiufei <xuejiufei@huawei.com>
To: ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] [PATCH V2] ocfs2: Check existence of old dentry in ocfs2_link()
Date: Sat, 8 Feb 2014 10:16:28 +0800 [thread overview]
Message-ID: <52F5937C.5050507@huawei.com> (raw)
System call linkat first calls user_path_at(), check the existence
of old dentry, and then calls vfs_link()->ocfs2_link() to do the actual
work. There may exist a race when Node A create a hard link for file
while node B rm it.
Node A Node B
user_path_at()
->ocfs2_lookup(),
find old dentry exist
rm file, add inode say inodeA
to orphan_dir
call ocfs2_link(),create a
hard link for inodeA.
rm the link, add inodeA to orphan_dir
again
When orphan_scan work start, it calls ocfs2_queue_orphans() to do
the main work. It first tranverses entrys in orphan_dir, linking
all inodes in this orphan_dir to a list look like this:
inodeA->inodeB->...->inodeA
When tranvering this list, it will fall into loop, calling iput() again and again.
And finally trigger BUG_ON(inode->i_state & I_CLEAR).
Signed-off-by: joyce <xuejiufei@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
---
fs/ocfs2/namei.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index f4d609b..3683643 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -664,6 +664,7 @@ static int ocfs2_link(struct dentry *old_dentry,
struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
struct ocfs2_dir_lookup_result lookup = { NULL, };
sigset_t oldset;
+ u64 old_de_ino;
trace_ocfs2_link((unsigned long long)OCFS2_I(inode)->ip_blkno,
old_dentry->d_name.len, old_dentry->d_name.name,
@@ -686,6 +687,22 @@ static int ocfs2_link(struct dentry *old_dentry,
goto out;
}
+ err = ocfs2_lookup_ino_from_name(dir, old_dentry->d_name.name,
+ old_dentry->d_name.len, &old_de_ino);
+ if (err) {
+ err = -ENOENT;
+ goto out;
+ }
+
+ /*
+ * Check whether another node removed the source inode while we
+ * were in the vfs.
+ */
+ if (old_de_ino != OCFS2_I(inode)->ip_blkno) {
+ err = -ENOENT;
+ goto out;
+ }
+
err = ocfs2_check_dir_for_entry(dir, dentry->d_name.name,
dentry->d_name.len);
if (err)
--
1.8.4.3
next reply other threads:[~2014-02-08 2:16 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-08 2:16 Xue jiufei [this message]
2014-02-10 21:47 ` [Ocfs2-devel] [PATCH V2] ocfs2: Check existence of old dentry in ocfs2_link() Mark Fasheh
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