[PATCH] lost content of /proc/sys/fs/binfmt_misc

From: Denis V. Lunev
Date: Wed Dec 05 2007 - 09:34:51 EST


/proc/sys/fs/binfmt_misc dentry disappeared during d_revalidate.
d_revalidate only dentries from shadowed one and below.
http://bugzilla.kernel.org/show_bug.cgi?id=9504

CC: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
CC: Marcus Better <marcus@xxxxxxxxx>
Signed-off-by: Denis V. Lunev <den@xxxxxxxxxx>

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 5fccfe2..1497ac4 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -380,12 +380,17 @@ static int proc_revalidate_dentry(struct dentry *dentry, struct nameidata *nd)
return 0;
}

-static struct dentry_operations proc_dentry_operations =
+static struct dentry_operations proc_dentry_shadow_operations =
{
.d_delete = proc_delete_dentry,
.d_revalidate = proc_revalidate_dentry,
};

+static struct dentry_operations proc_dentry_operations =
+{
+ .d_delete = proc_delete_dentry,
+};
+
/*
* Don't create negative dentries here, return -ENOENT by hand
* instead.
@@ -394,6 +399,7 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam
{
struct inode *inode = NULL;
struct proc_dir_entry * de;
+ int use_shadow = 0;
int error = -ENOENT;

lock_kernel();
@@ -406,8 +412,10 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam
if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
unsigned int ino;

- if (de->shadow_proc)
+ if (de->shadow_proc) {
de = de->shadow_proc(current, de);
+ use_shadow = 1;
+ }
ino = de->low_ino;
de_get(de);
spin_unlock(&proc_subdir_lock);
@@ -423,6 +431,8 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam

if (inode) {
dentry->d_op = &proc_dentry_operations;
+ dentry->d_op = use_shadow ?
+ &proc_dentry_shadow_operations : dentry->d_parent->d_op;
d_add(dentry, inode);
return NULL;
}
--
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