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authorAl Viro <viro@zeniv.linux.org.uk>2015-11-17 10:20:54 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2015-12-08 22:41:54 -0500
commit6b2553918d8b4e6de9853fd6315bec7271a2e592 (patch)
tree85540dcb0dc0de3d67c68d0aa7b17058f4e96539 /fs/proc
parent21fc61c73c3903c4c312d0802da01ec2b323d174 (diff)
downloadlinux-6b2553918d8b4e6de9853fd6315bec7271a2e592.tar.bz2
replace ->follow_link() with new method that could stay in RCU mode
new method: ->get_link(); replacement of ->follow_link(). The differences are: * inode and dentry are passed separately * might be called both in RCU and non-RCU mode; the former is indicated by passing it a NULL dentry. * when called that way it isn't allowed to block and should return ERR_PTR(-ECHILD) if it needs to be called in non-RCU mode. It's a flagday change - the old method is gone, all in-tree instances converted. Conversion isn't hard; said that, so far very few instances do not immediately bail out when called in RCU mode. That'll change in the next commits. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c22
-rw-r--r--fs/proc/inode.c7
-rw-r--r--fs/proc/namespaces.c9
-rw-r--r--fs/proc/self.c9
-rw-r--r--fs/proc/thread_self.c9
5 files changed, 35 insertions, 21 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index bd3e9e68125b..1a489e2b9768 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1564,12 +1564,15 @@ static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
return -ENOENT;
}
-static const char *proc_pid_follow_link(struct dentry *dentry, void **cookie)
+static const char *proc_pid_get_link(struct dentry *dentry,
+ struct inode *inode, void **cookie)
{
- struct inode *inode = d_inode(dentry);
struct path path;
int error = -EACCES;
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
+
/* Are we allowed to snoop on the tasks file descriptors? */
if (!proc_fd_access_allowed(inode))
goto out;
@@ -1630,7 +1633,7 @@ out:
const struct inode_operations proc_pid_link_inode_operations = {
.readlink = proc_pid_readlink,
- .follow_link = proc_pid_follow_link,
+ .get_link = proc_pid_get_link,
.setattr = proc_setattr,
};
@@ -1895,7 +1898,7 @@ static const struct dentry_operations tid_map_files_dentry_operations = {
.d_delete = pid_delete_dentry,
};
-static int proc_map_files_get_link(struct dentry *dentry, struct path *path)
+static int map_files_get_link(struct dentry *dentry, struct path *path)
{
unsigned long vm_start, vm_end;
struct vm_area_struct *vma;
@@ -1945,20 +1948,21 @@ struct map_files_info {
* path to the file in question.
*/
static const char *
-proc_map_files_follow_link(struct dentry *dentry, void **cookie)
+proc_map_files_get_link(struct dentry *dentry,
+ struct inode *inode, void **cookie)
{
if (!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
- return proc_pid_follow_link(dentry, NULL);
+ return proc_pid_get_link(dentry, inode, NULL);
}
/*
- * Identical to proc_pid_link_inode_operations except for follow_link()
+ * Identical to proc_pid_link_inode_operations except for get_link()
*/
static const struct inode_operations proc_map_files_link_inode_operations = {
.readlink = proc_pid_readlink,
- .follow_link = proc_map_files_follow_link,
+ .get_link = proc_map_files_get_link,
.setattr = proc_setattr,
};
@@ -1975,7 +1979,7 @@ proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
return -ENOENT;
ei = PROC_I(inode);
- ei->op.proc_get_link = proc_map_files_get_link;
+ ei->op.proc_get_link = map_files_get_link;
inode->i_op = &proc_map_files_link_inode_operations;
inode->i_size = 64;
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index bd95b9fdebb0..10360b268794 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -393,9 +393,10 @@ static const struct file_operations proc_reg_file_ops_no_compat = {
};
#endif
-static const char *proc_follow_link(struct dentry *dentry, void **cookie)
+static const char *proc_get_link(struct dentry *dentry,
+ struct inode *inode, void **cookie)
{
- struct proc_dir_entry *pde = PDE(d_inode(dentry));
+ struct proc_dir_entry *pde = PDE(inode);
if (unlikely(!use_pde(pde)))
return ERR_PTR(-EINVAL);
*cookie = pde;
@@ -409,7 +410,7 @@ static void proc_put_link(struct inode *unused, void *p)
const struct inode_operations proc_link_inode_operations = {
.readlink = generic_readlink,
- .follow_link = proc_follow_link,
+ .get_link = proc_get_link,
.put_link = proc_put_link,
};
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index f6e8354b8cea..63861c15e109 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -30,14 +30,17 @@ static const struct proc_ns_operations *ns_entries[] = {
&mntns_operations,
};
-static const char *proc_ns_follow_link(struct dentry *dentry, void **cookie)
+static const char *proc_ns_get_link(struct dentry *dentry,
+ struct inode *inode, void **cookie)
{
- struct inode *inode = d_inode(dentry);
const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
struct task_struct *task;
struct path ns_path;
void *error = ERR_PTR(-EACCES);
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
+
task = get_proc_task(inode);
if (!task)
return error;
@@ -74,7 +77,7 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl
static const struct inode_operations proc_ns_link_inode_operations = {
.readlink = proc_ns_readlink,
- .follow_link = proc_ns_follow_link,
+ .get_link = proc_ns_get_link,
.setattr = proc_setattr,
};
diff --git a/fs/proc/self.c b/fs/proc/self.c
index 113b8d061fc0..9dd0ae6aefdb 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -18,12 +18,15 @@ static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
return readlink_copy(buffer, buflen, tmp);
}
-static const char *proc_self_follow_link(struct dentry *dentry, void **cookie)
+static const char *proc_self_get_link(struct dentry *dentry,
+ struct inode *inode, void **cookie)
{
- struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+ struct pid_namespace *ns = inode->i_sb->s_fs_info;
pid_t tgid = task_tgid_nr_ns(current, ns);
char *name;
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
if (!tgid)
return ERR_PTR(-ENOENT);
/* 11 for max length of signed int in decimal + NULL term */
@@ -36,7 +39,7 @@ static const char *proc_self_follow_link(struct dentry *dentry, void **cookie)
static const struct inode_operations proc_self_inode_operations = {
.readlink = proc_self_readlink,
- .follow_link = proc_self_follow_link,
+ .get_link = proc_self_get_link,
.put_link = kfree_put_link,
};
diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index 947b0f4fd0a1..50eef6f3e671 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -19,13 +19,16 @@ static int proc_thread_self_readlink(struct dentry *dentry, char __user *buffer,
return readlink_copy(buffer, buflen, tmp);
}
-static const char *proc_thread_self_follow_link(struct dentry *dentry, void **cookie)
+static const char *proc_thread_self_get_link(struct dentry *dentry,
+ struct inode *inode, void **cookie)
{
- struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+ struct pid_namespace *ns = inode->i_sb->s_fs_info;
pid_t tgid = task_tgid_nr_ns(current, ns);
pid_t pid = task_pid_nr_ns(current, ns);
char *name;
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
if (!pid)
return ERR_PTR(-ENOENT);
name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, GFP_KERNEL);
@@ -37,7 +40,7 @@ static const char *proc_thread_self_follow_link(struct dentry *dentry, void **co
static const struct inode_operations proc_thread_self_inode_operations = {
.readlink = proc_thread_self_readlink,
- .follow_link = proc_thread_self_follow_link,
+ .get_link = proc_thread_self_get_link,
.put_link = kfree_put_link,
};