forked from Minki/linux
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: get rid of nameidata_dentry_drop_rcu() calling nameidata_drop_rcu() drop out of RCU in return_reval split do_revalidate() into RCU and non-RCU cases in do_lookup() split RCU and non-RCU cases of need_revalidate nothing in do_follow_link() is going to see RCU
This commit is contained in:
Linus Torvalds
commit
055d219441
122
fs/namei.c
122
fs/namei.c
@ -455,14 +455,6 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry
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struct fs_struct *fs = current->fs;
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struct dentry *parent = nd->path.dentry;
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/*
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* It can be possible to revalidate the dentry that we started
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* the path walk with. force_reval_path may also revalidate the
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* dentry already committed to the nameidata.
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*/
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if (unlikely(parent == dentry))
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return nameidata_drop_rcu(nd);
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BUG_ON(!(nd->flags & LOOKUP_RCU));
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if (nd->root.mnt) {
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spin_lock(&fs->lock);
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@ -571,33 +563,15 @@ void release_open_intent(struct nameidata *nd)
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}
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}
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/*
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* Call d_revalidate and handle filesystems that request rcu-walk
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* to be dropped. This may be called and return in rcu-walk mode,
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* regardless of success or error. If -ECHILD is returned, the caller
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* must return -ECHILD back up the path walk stack so path walk may
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* be restarted in ref-walk mode.
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*/
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static int d_revalidate(struct dentry *dentry, struct nameidata *nd)
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static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
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{
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int status;
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status = dentry->d_op->d_revalidate(dentry, nd);
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if (status == -ECHILD) {
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if (nameidata_dentry_drop_rcu(nd, dentry))
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return status;
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status = dentry->d_op->d_revalidate(dentry, nd);
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}
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return status;
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return dentry->d_op->d_revalidate(dentry, nd);
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}
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static inline struct dentry *
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static struct dentry *
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do_revalidate(struct dentry *dentry, struct nameidata *nd)
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{
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int status;
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status = d_revalidate(dentry, nd);
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int status = d_revalidate(dentry, nd);
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if (unlikely(status <= 0)) {
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/*
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* The dentry failed validation.
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@ -606,24 +580,39 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
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* to return a fail status.
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*/
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if (status < 0) {
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/* If we're in rcu-walk, we don't have a ref */
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if (!(nd->flags & LOOKUP_RCU))
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dput(dentry);
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dput(dentry);
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dentry = ERR_PTR(status);
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} else {
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/* Don't d_invalidate in rcu-walk mode */
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if (nameidata_dentry_drop_rcu_maybe(nd, dentry))
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return ERR_PTR(-ECHILD);
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if (!d_invalidate(dentry)) {
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dput(dentry);
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dentry = NULL;
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}
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} else if (!d_invalidate(dentry)) {
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dput(dentry);
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dentry = NULL;
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}
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}
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return dentry;
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}
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static inline struct dentry *
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do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd)
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{
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int status = d_revalidate(dentry, nd);
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if (likely(status > 0))
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return dentry;
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if (status == -ECHILD) {
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if (nameidata_dentry_drop_rcu(nd, dentry))
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return ERR_PTR(-ECHILD);
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return do_revalidate(dentry, nd);
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}
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if (status < 0)
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return ERR_PTR(status);
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/* Don't d_invalidate in rcu-walk mode */
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if (nameidata_dentry_drop_rcu(nd, dentry))
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return ERR_PTR(-ECHILD);
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if (!d_invalidate(dentry)) {
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dput(dentry);
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dentry = NULL;
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}
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return dentry;
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}
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static inline int need_reval_dot(struct dentry *dentry)
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{
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if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
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@ -668,9 +657,6 @@ force_reval_path(struct path *path, struct nameidata *nd)
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return 0;
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if (!status) {
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/* Don't d_invalidate in rcu-walk mode */
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if (nameidata_drop_rcu(nd))
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return -ECHILD;
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d_invalidate(dentry);
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status = -ESTALE;
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}
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@ -777,6 +763,8 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
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int error;
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struct dentry *dentry = link->dentry;
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BUG_ON(nd->flags & LOOKUP_RCU);
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touch_atime(link->mnt, dentry);
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nd_set_link(nd, NULL);
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@ -811,6 +799,11 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd)
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{
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void *cookie;
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int err = -ELOOP;
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/* We drop rcu-walk here */
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if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry))
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return -ECHILD;
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if (current->link_count >= MAX_NESTED_LINKS)
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goto loop;
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if (current->total_link_count >= 40)
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@ -1255,9 +1248,15 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
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return -ECHILD;
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nd->seq = seq;
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if (dentry->d_flags & DCACHE_OP_REVALIDATE)
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goto need_revalidate;
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done2:
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if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
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dentry = do_revalidate_rcu(dentry, nd);
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if (!dentry)
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goto need_lookup;
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if (IS_ERR(dentry))
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goto fail;
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if (!(nd->flags & LOOKUP_RCU))
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goto done;
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}
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path->mnt = mnt;
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path->dentry = dentry;
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if (likely(__follow_mount_rcu(nd, path, inode, false)))
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@ -1270,8 +1269,13 @@ done2:
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if (!dentry)
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goto need_lookup;
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found:
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if (dentry->d_flags & DCACHE_OP_REVALIDATE)
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goto need_revalidate;
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if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
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dentry = do_revalidate(dentry, nd);
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if (!dentry)
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goto need_lookup;
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if (IS_ERR(dentry))
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goto fail;
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}
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done:
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path->mnt = mnt;
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path->dentry = dentry;
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@ -1313,16 +1317,6 @@ need_lookup:
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mutex_unlock(&dir->i_mutex);
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goto found;
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need_revalidate:
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dentry = do_revalidate(dentry, nd);
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if (!dentry)
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goto need_lookup;
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if (IS_ERR(dentry))
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goto fail;
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if (nd->flags & LOOKUP_RCU)
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goto done2;
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goto done;
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fail:
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return PTR_ERR(dentry);
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}
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@ -1419,9 +1413,6 @@ exec_again:
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goto out_dput;
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if (inode->i_op->follow_link) {
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/* We commonly drop rcu-walk here */
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if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
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return -ECHILD;
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BUG_ON(inode != next.dentry->d_inode);
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err = do_follow_link(&next, nd);
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if (err)
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@ -1467,8 +1458,6 @@ last_component:
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break;
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if (inode && unlikely(inode->i_op->follow_link) &&
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(lookup_flags & LOOKUP_FOLLOW)) {
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if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry))
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return -ECHILD;
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BUG_ON(inode != next.dentry->d_inode);
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err = do_follow_link(&next, nd);
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if (err)
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@ -1504,12 +1493,15 @@ return_reval:
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* We may need to check the cached dentry for staleness.
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*/
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if (need_reval_dot(nd->path.dentry)) {
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if (nameidata_drop_rcu_last_maybe(nd))
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return -ECHILD;
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/* Note: we do not d_invalidate() */
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err = d_revalidate(nd->path.dentry, nd);
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if (!err)
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err = -ESTALE;
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if (err < 0)
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break;
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return 0;
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}
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return_base:
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if (nameidata_drop_rcu_last_maybe(nd))
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