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authorAl Viro <viro@zeniv.linux.org.uk>2014-09-13 21:55:46 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2014-09-14 14:19:44 -0400
commit7bd88377d482e1eae3c5329b12e33cfd664fa6a9 (patch)
tree814293d29b98c33b887c3140c11e24ccffbf9862
parentf5be3e29127aec8c87f883aadadff337f8c2cfd7 (diff)
downloadop-kernel-dev-7bd88377d482e1eae3c5329b12e33cfd664fa6a9.zip
op-kernel-dev-7bd88377d482e1eae3c5329b12e33cfd664fa6a9.tar.gz
don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu()
return the value instead, and have path_init() do the assignment. Broken by "vfs: Fix absolute RCU path walk failures due to uninitialized seq number", which was Cc-stable with 2.6.38+ as destination. This one should go where it went. To avoid dummy value returned in case when root is already set (it would do no harm, actually, since the only caller that doesn't ignore the return value is guaranteed to have nd->root *not* set, but it's more obvious that way), lift the check into callers. And do the same to set_root(), to keep them in sync. Cc: stable@vger.kernel.org # 2.6.38+ Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/namei.c33
1 files changed, 17 insertions, 16 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 3d1dc74..fe47e6d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -643,24 +643,22 @@ static int complete_walk(struct nameidata *nd)
static __always_inline void set_root(struct nameidata *nd)
{
- if (!nd->root.mnt)
- get_fs_root(current->fs, &nd->root);
+ get_fs_root(current->fs, &nd->root);
}
static int link_path_walk(const char *, struct nameidata *);
-static __always_inline void set_root_rcu(struct nameidata *nd)
+static __always_inline unsigned set_root_rcu(struct nameidata *nd)
{
- if (!nd->root.mnt) {
- struct fs_struct *fs = current->fs;
- unsigned seq;
+ struct fs_struct *fs = current->fs;
+ unsigned seq, res;
- do {
- seq = read_seqcount_begin(&fs->seq);
- nd->root = fs->root;
- nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
- } while (read_seqcount_retry(&fs->seq, seq));
- }
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ res = __read_seqcount_begin(&nd->root.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ return res;
}
static void path_put_conditional(struct path *path, struct nameidata *nd)
@@ -860,7 +858,8 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
return PTR_ERR(s);
}
if (*s == '/') {
- set_root(nd);
+ if (!nd->root.mnt)
+ set_root(nd);
path_put(&nd->path);
nd->path = nd->root;
path_get(&nd->root);
@@ -1143,7 +1142,8 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
static int follow_dotdot_rcu(struct nameidata *nd)
{
- set_root_rcu(nd);
+ if (!nd->root.mnt)
+ set_root_rcu(nd);
while (1) {
if (nd->path.dentry == nd->root.dentry &&
@@ -1256,7 +1256,8 @@ static void follow_mount(struct path *path)
static void follow_dotdot(struct nameidata *nd)
{
- set_root(nd);
+ if (!nd->root.mnt)
+ set_root(nd);
while(1) {
struct dentry *old = nd->path.dentry;
@@ -1852,7 +1853,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
if (*name=='/') {
if (flags & LOOKUP_RCU) {
rcu_read_lock();
- set_root_rcu(nd);
+ nd->seq = set_root_rcu(nd);
} else {
set_root(nd);
path_get(&nd->root);
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