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-rw-r--r--fs/namei.c122
1 files changed, 57 insertions, 65 deletions
diff --git a/fs/namei.c b/fs/namei.c
index ec4b2d0190a..9e701e28a32 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -455,14 +455,6 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry
struct fs_struct *fs = current->fs;
struct dentry *parent = nd->path.dentry;
- /*
- * It can be possible to revalidate the dentry that we started
- * the path walk with. force_reval_path may also revalidate the
- * dentry already committed to the nameidata.
- */
- if (unlikely(parent == dentry))
- return nameidata_drop_rcu(nd);
-
BUG_ON(!(nd->flags & LOOKUP_RCU));
if (nd->root.mnt) {
spin_lock(&fs->lock);
@@ -571,33 +563,15 @@ void release_open_intent(struct nameidata *nd)
}
}
-/*
- * Call d_revalidate and handle filesystems that request rcu-walk
- * to be dropped. This may be called and return in rcu-walk mode,
- * regardless of success or error. If -ECHILD is returned, the caller
- * must return -ECHILD back up the path walk stack so path walk may
- * be restarted in ref-walk mode.
- */
-static int d_revalidate(struct dentry *dentry, struct nameidata *nd)
+static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
{
- int status;
-
- status = dentry->d_op->d_revalidate(dentry, nd);
- if (status == -ECHILD) {
- if (nameidata_dentry_drop_rcu(nd, dentry))
- return status;
- status = dentry->d_op->d_revalidate(dentry, nd);
- }
-
- return status;
+ return dentry->d_op->d_revalidate(dentry, nd);
}
-static inline struct dentry *
+static struct dentry *
do_revalidate(struct dentry *dentry, struct nameidata *nd)
{
- int status;
-
- status = d_revalidate(dentry, nd);
+ int status = d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
/*
* The dentry failed validation.
@@ -606,24 +580,39 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
* to return a fail status.
*/
if (status < 0) {
- /* If we're in rcu-walk, we don't have a ref */
- if (!(nd->flags & LOOKUP_RCU))
- dput(dentry);
+ dput(dentry);
dentry = ERR_PTR(status);
-
- } else {
- /* Don't d_invalidate in rcu-walk mode */
- if (nameidata_dentry_drop_rcu_maybe(nd, dentry))
- return ERR_PTR(-ECHILD);
- if (!d_invalidate(dentry)) {
- dput(dentry);
- dentry = NULL;
- }
+ } else if (!d_invalidate(dentry)) {
+ dput(dentry);
+ dentry = NULL;
}
}
return dentry;
}
+static inline struct dentry *
+do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd)
+{
+ int status = d_revalidate(dentry, nd);
+ if (likely(status > 0))
+ return dentry;
+ if (status == -ECHILD) {
+ if (nameidata_dentry_drop_rcu(nd, dentry))
+ return ERR_PTR(-ECHILD);
+ return do_revalidate(dentry, nd);
+ }
+ if (status < 0)
+ return ERR_PTR(status);
+ /* Don't d_invalidate in rcu-walk mode */
+ if (nameidata_dentry_drop_rcu(nd, dentry))
+ return ERR_PTR(-ECHILD);
+ if (!d_invalidate(dentry)) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ return dentry;
+}
+
static inline int need_reval_dot(struct dentry *dentry)
{
if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
@@ -668,9 +657,6 @@ force_reval_path(struct path *path, struct nameidata *nd)
return 0;
if (!status) {
- /* Don't d_invalidate in rcu-walk mode */
- if (nameidata_drop_rcu(nd))
- return -ECHILD;
d_invalidate(dentry);
status = -ESTALE;
}
@@ -777,6 +763,8 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
int error;
struct dentry *dentry = link->dentry;
+ BUG_ON(nd->flags & LOOKUP_RCU);
+
touch_atime(link->mnt, dentry);
nd_set_link(nd, NULL);
@@ -811,6 +799,11 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd)
{
void *cookie;
int err = -ELOOP;
+
+ /* We drop rcu-walk here */
+ if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
+ return -ECHILD;
+
if (current->link_count >= MAX_NESTED_LINKS)
goto loop;
if (current->total_link_count >= 40)
@@ -1255,9 +1248,15 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
return -ECHILD;
nd->seq = seq;
- if (dentry->d_flags & DCACHE_OP_REVALIDATE)
- goto need_revalidate;
-done2:
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
+ dentry = do_revalidate_rcu(dentry, nd);
+ if (!dentry)
+ goto need_lookup;
+ if (IS_ERR(dentry))
+ goto fail;
+ if (!(nd->flags & LOOKUP_RCU))
+ goto done;
+ }
path->mnt = mnt;
path->dentry = dentry;
if (likely(__follow_mount_rcu(nd, path, inode, false)))
@@ -1270,8 +1269,13 @@ done2:
if (!dentry)
goto need_lookup;
found:
- if (dentry->d_flags & DCACHE_OP_REVALIDATE)
- goto need_revalidate;
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
+ dentry = do_revalidate(dentry, nd);
+ if (!dentry)
+ goto need_lookup;
+ if (IS_ERR(dentry))
+ goto fail;
+ }
done:
path->mnt = mnt;
path->dentry = dentry;
@@ -1313,16 +1317,6 @@ need_lookup:
mutex_unlock(&dir->i_mutex);
goto found;
-need_revalidate:
- dentry = do_revalidate(dentry, nd);
- if (!dentry)
- goto need_lookup;
- if (IS_ERR(dentry))
- goto fail;
- if (nd->flags & LOOKUP_RCU)
- goto done2;
- goto done;
-
fail:
return PTR_ERR(dentry);
}
@@ -1419,9 +1413,6 @@ exec_again:
goto out_dput;
if (inode->i_op->follow_link) {
- /* We commonly drop rcu-walk here */
- if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
- return -ECHILD;
BUG_ON(inode != next.dentry->d_inode);
err = do_follow_link(&next, nd);
if (err)
@@ -1467,8 +1458,6 @@ last_component:
break;
if (inode && unlikely(inode->i_op->follow_link) &&
(lookup_flags & LOOKUP_FOLLOW)) {
- if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
- return -ECHILD;
BUG_ON(inode != next.dentry->d_inode);
err = do_follow_link(&next, nd);
if (err)
@@ -1504,12 +1493,15 @@ return_reval:
* We may need to check the cached dentry for staleness.
*/
if (need_reval_dot(nd->path.dentry)) {
+ if (nameidata_drop_rcu_last_maybe(nd))
+ return -ECHILD;
/* Note: we do not d_invalidate() */
err = d_revalidate(nd->path.dentry, nd);
if (!err)
err = -ESTALE;
if (err < 0)
break;
+ return 0;
}
return_base:
if (nameidata_drop_rcu_last_maybe(nd))
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-28 03:09:33 +0000