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Commit 58c465eb authored by Al Viro's avatar Al Viro Committed by Linus Torvalds
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[PATCH] namei fixes (17/19) 



follow_mount() made void, reordered dput()/mntput() in it.

follow_dotdot() switched from struct vfmount ** + struct dentry ** to
struct nameidata *; callers updated.

Equivalent transformation + fix for too-early-mntput() race.

Signed-off-by: default avatarAl Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 39ca6d49

fs/namei.c

+16 −19
Original line number Diff line number Diff line
@@ -596,20 +596,17 @@ static int __follow_mount(struct path *path) 
	return res;

}



static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)

static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)

{

	int res = 0;

	while (d_mountpoint(*dentry)) {

		struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);

		if (!mounted)

			break;

		dput(*dentry);

		mntput(*mnt);

		*mnt = mounted;

		dput(*dentry);

		*dentry = dget(mounted->mnt_root);

		res = 1;

	}

	return res;

}



/* no need for dcache_lock, as serialization is taken care in
@@ -630,41 +627,41 @@ int follow_down(struct vfsmount **mnt, struct dentry **dentry) 
	return 0;

}



static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)

static inline void follow_dotdot(struct nameidata *nd)

{

	while(1) {

		struct vfsmount *parent;

		struct dentry *old = *dentry;

		struct dentry *old = nd->dentry;



                read_lock(&current->fs->lock);

		if (*dentry == current->fs->root &&

		    *mnt == current->fs->rootmnt) {

		if (nd->dentry == current->fs->root &&

		    nd->mnt == current->fs->rootmnt) {

                        read_unlock(&current->fs->lock);

			break;

		}

                read_unlock(&current->fs->lock);

		spin_lock(&dcache_lock);

		if (*dentry != (*mnt)->mnt_root) {

			*dentry = dget((*dentry)->d_parent);

		if (nd->dentry != nd->mnt->mnt_root) {

			nd->dentry = dget(nd->dentry->d_parent);

			spin_unlock(&dcache_lock);

			dput(old);

			break;

		}

		spin_unlock(&dcache_lock);

		spin_lock(&vfsmount_lock);

		parent = (*mnt)->mnt_parent;

		if (parent == *mnt) {

		parent = nd->mnt->mnt_parent;

		if (parent == nd->mnt) {

			spin_unlock(&vfsmount_lock);

			break;

		}

		mntget(parent);

		*dentry = dget((*mnt)->mnt_mountpoint);

		nd->dentry = dget(nd->mnt->mnt_mountpoint);

		spin_unlock(&vfsmount_lock);

		dput(old);

		mntput(*mnt);

		*mnt = parent;

		mntput(nd->mnt);

		nd->mnt = parent;

	}

	follow_mount(mnt, dentry);

	follow_mount(&nd->mnt, &nd->dentry);

}



/*
@@ -772,7 +769,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd) 
			case 2:	

				if (this.name[1] != '.')

					break;

				follow_dotdot(&nd->mnt, &nd->dentry);

				follow_dotdot(nd);

				inode = nd->dentry->d_inode;

				/* fallthrough */

			case 1:
@@ -839,7 +836,7 @@ last_component: 
			case 2:	

				if (this.name[1] != '.')

					break;

				follow_dotdot(&nd->mnt, &nd->dentry);

				follow_dotdot(nd);

				inode = nd->dentry->d_inode;

				/* fallthrough */

			case 1: