namei: explicitly pass seq number to unlazy_walk() when dentry != NULL (6e9918b7) · Commits · e / devices / android_kernel_fairphone_FP3

fs/namei.c

+8 −7

Original line number	Diff line number	Diff line
		@@ -567,13 +567,14 @@ static inline int nd_alloc_stack(struct nameidata *nd)
		* unlazy_walk - try to switch to ref-walk mode.
		* @nd: nameidata pathwalk data
		* @dentry: child of nd->path.dentry or NULL
		* @seq: seq number to check dentry against
		* Returns: 0 on success, -ECHILD on failure
		*
		* unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry
		* for ref-walk mode. @dentry must be a path found by a do_lookup call on
		* @nd or NULL. Must be called from rcu-walk context.
		*/
		static int unlazy_walk(struct nameidata nd, struct dentry dentry)
		static int unlazy_walk(struct nameidata nd, struct dentry dentry, unsigned seq)
		{
		struct fs_struct *fs = current->fs;
		struct dentry *parent = nd->path.dentry;
		@@ -615,7 +616,7 @@ static int unlazy_walk(struct nameidata nd, struct dentry dentry)
		} else {
		if (!lockref_get_not_dead(&dentry->d_lockref))
		goto out;
		if (read_seqcount_retry(&dentry->d_seq, nd->seq))
		if (read_seqcount_retry(&dentry->d_seq, seq))
		goto drop_dentry;
		}

		@@ -671,7 +672,7 @@ static int complete_walk(struct nameidata *nd)
		if (nd->flags & LOOKUP_RCU) {
		if (!(nd->flags & LOOKUP_ROOT))
		nd->root.mnt = NULL;
		if (unlikely(unlazy_walk(nd, NULL)))
		if (unlikely(unlazy_walk(nd, NULL, 0)))
		return -ECHILD;
		}

		@@ -1451,7 +1452,7 @@ static int lookup_fast(struct nameidata *nd,
		if (likely(__follow_mount_rcu(nd, path, inode)))
		return 0;
		unlazy:
		if (unlazy_walk(nd, dentry))
		if (unlazy_walk(nd, dentry, nd->seq))
		return -ECHILD;
		} else {
		dentry = __d_lookup(parent, &nd->last);
		@@ -1511,7 +1512,7 @@ static inline int may_lookup(struct nameidata *nd)
		int err = inode_permission(nd->inode, MAY_EXEC\|MAY_NOT_BLOCK);
		if (err != -ECHILD)
		return err;
		if (unlazy_walk(nd, NULL))
		if (unlazy_walk(nd, NULL, 0))
		return -ECHILD;
		}
		return inode_permission(nd->inode, MAY_EXEC);
		@@ -1552,7 +1553,7 @@ static int pick_link(struct nameidata nd, struct path link)
		}
		if (nd->flags & LOOKUP_RCU) {
		if (unlikely(nd->path.mnt != link->mnt \|\|
		unlazy_walk(nd, link->dentry))) {
		unlazy_walk(nd, link->dentry, nd->seq))) {
		return -ECHILD;
		}
		}
		@@ -2297,7 +2298,7 @@ mountpoint_last(struct nameidata nd, struct path path)

		/* If we're in rcuwalk, drop out of it to handle last component */
		if (nd->flags & LOOKUP_RCU) {
		if (unlazy_walk(nd, NULL))
		if (unlazy_walk(nd, NULL, 0))
		return -ECHILD;
		}