3.2.64-rc1 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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/namei.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -913,6 +913,7 @@ static bool __follow_mount_rcu(struct na
static int follow_dotdot_rcu(struct nameidata *nd)
{
+ struct inode *inode = nd->inode;
if (!nd->root.mnt)
set_root_rcu(nd);
@@ -926,6 +927,7 @@ static int follow_dotdot_rcu(struct name
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;
@@ -935,6 +937,7 @@ static int follow_dotdot_rcu(struct name
}
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)) {
@@ -944,9 +947,10 @@ static int follow_dotdot_rcu(struct name
break;
nd->path.mnt = mounted;
nd->path.dentry = mounted->mnt_root;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
- nd->inode = nd->path.dentry->d_inode;
+ nd->inode = inode;
return 0;
failed:
@@ -1556,7 +1560,14 @@ static int path_init(int dfd, const char
}
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;
fput_fail:
fput_light(file, fput_needed);
--
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