3.16.7-ckt1 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit 4023bfc9f351a7994fb6a7d515476c320f94a574 upstream.
in the former we simply check if dentry is still valid after picking
its ->d_inode; in the latter we fetch ->d_inode in the same places
where we fetch dentry and its ->d_seq, under the same checks.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
fs/namei.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index d4ca42085e1d..8a3bdeae730c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1135,6 +1135,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
static int follow_dotdot_rcu(struct nameidata *nd)
{
+ struct inode *inode = nd->inode;
if (!nd->root.mnt)
set_root_rcu(nd);
@@ -1148,6 +1149,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
struct dentry *parent = old->d_parent;
unsigned seq;
+ inode = parent->d_inode;
seq = read_seqcount_begin(&parent->d_seq);
if (read_seqcount_retry(&old->d_seq, nd->seq))
goto failed;
@@ -1157,6 +1159,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
}
if (!follow_up_rcu(&nd->path))
break;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
while (d_mountpoint(nd->path.dentry)) {
@@ -1166,11 +1169,12 @@ static int follow_dotdot_rcu(struct nameidata *nd)
break;
nd->path.mnt = &mounted->mnt;
nd->path.dentry = mounted->mnt.mnt_root;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
if (!read_seqretry(&mount_lock, nd->m_seq))
goto failed;
}
- nd->inode = nd->path.dentry->d_inode;
+ nd->inode = inode;
return 0;
failed:
@@ -1899,7 +1903,14 @@ static int path_init(int dfd, const char *name, unsigned int flags,
}
nd->inode = nd->path.dentry->d_inode;
- return 0;
+ if (!(flags & LOOKUP_RCU))
+ return 0;
+ if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
+ return 0;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ return -ECHILD;
}
static inline int lookup_last(struct nameidata *nd, struct path *path)
--
2.1.0
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