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Subject[PATCH 21/42] Unionfs: inode operations
Date
Includes create, lookup, link, symlink, mkdir, mknod, readlink, follow_link,
put_link, permission, and setattr.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
fs/unionfs/inode.c | 1154 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 1154 insertions(+), 0 deletions(-)
create mode 100644 fs/unionfs/inode.c

diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
new file mode 100644
index 0000000..63ff3d3
--- /dev/null
+++ b/fs/unionfs/inode.c
@@ -0,0 +1,1154 @@
+/*
+ * Copyright (c) 2003-2007 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2007 Josef 'Jeff' Sipek
+ * Copyright (c) 2005-2006 Junjiro Okajima
+ * Copyright (c) 2005 Arun M. Krishnakumar
+ * Copyright (c) 2004-2006 David P. Quigley
+ * Copyright (c) 2003-2004 Mohammad Nayyer Zubair
+ * Copyright (c) 2003 Puja Gupta
+ * Copyright (c) 2003 Harikesavan Krishnan
+ * Copyright (c) 2003-2007 Stony Brook University
+ * Copyright (c) 2003-2007 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "union.h"
+
+static int unionfs_create(struct inode *parent, struct dentry *dentry,
+ int mode, struct nameidata *nd)
+{
+ int err = 0;
+ struct dentry *lower_dentry = NULL;
+ struct dentry *wh_dentry = NULL;
+ struct dentry *lower_parent_dentry = NULL;
+ char *name = NULL;
+ int valid = 0;
+ struct nameidata lower_nd;
+
+ unionfs_read_lock(dentry->d_sb);
+ unionfs_lock_dentry(dentry);
+
+ unionfs_lock_dentry(dentry->d_parent);
+ valid = __unionfs_d_revalidate_chain(dentry->d_parent, nd, false);
+ unionfs_unlock_dentry(dentry->d_parent);
+ if (unlikely(!valid)) {
+ err = -ESTALE; /* same as what real_lookup does */
+ goto out;
+ }
+ valid = __unionfs_d_revalidate_chain(dentry, nd, false);
+ /*
+ * It's only a bug if this dentry was not negative and couldn't be
+ * revalidated (shouldn't happen).
+ */
+ BUG_ON(!valid && dentry->d_inode);
+
+ /*
+ * We shouldn't create things in a read-only branch; this check is a
+ * bit redundant as we don't allow branch 0 to be read-only at the
+ * moment
+ */
+ err = is_robranch_super(dentry->d_sb, 0);
+ if (err) {
+ err = -EROFS;
+ goto out;
+ }
+
+ /*
+ * We _always_ create on branch 0
+ */
+ lower_dentry = unionfs_lower_dentry_idx(dentry, 0);
+ if (lower_dentry) {
+ /*
+ * check if whiteout exists in this branch, i.e. lookup .wh.foo
+ * first.
+ */
+ name = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+ if (unlikely(IS_ERR(name))) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ wh_dentry = lookup_one_len(name, lower_dentry->d_parent,
+ dentry->d_name.len + UNIONFS_WHLEN);
+ if (IS_ERR(wh_dentry)) {
+ err = PTR_ERR(wh_dentry);
+ wh_dentry = NULL;
+ goto out;
+ }
+
+ if (wh_dentry->d_inode) {
+ /*
+ * .wh.foo has been found, so let's unlink it
+ */
+ struct dentry *lower_dir_dentry;
+
+ lower_dir_dentry = lock_parent(wh_dentry);
+ err = vfs_unlink(lower_dir_dentry->d_inode, wh_dentry);
+ unlock_dir(lower_dir_dentry);
+
+ /*
+ * Whiteouts are special files and should be deleted
+ * no matter what (as if they never existed), in
+ * order to allow this create operation to succeed.
+ * This is especially important in sticky
+ * directories: a whiteout may have been created by
+ * one user, but the newly created file may be
+ * created by another user. Therefore, in order to
+ * maintain Unix semantics, if the vfs_unlink above
+ * ailed, then we have to try to directly unlink the
+ * whiteout. Note: in the ODF version of unionfs,
+ * whiteout are handled much more cleanly.
+ */
+ if (err == -EPERM) {
+ struct inode *inode = lower_dir_dentry->d_inode;
+ err = inode->i_op->unlink(inode, wh_dentry);
+ }
+ if (err) {
+ printk(KERN_ERR "unionfs: create: could not "
+ "unlink whiteout, err = %d\n", err);
+ goto out;
+ }
+ }
+ } else {
+ /*
+ * if lower_dentry is NULL, create the entire
+ * dentry directory structure in branch 0.
+ */
+ lower_dentry = create_parents(parent, dentry,
+ dentry->d_name.name, 0);
+ if (IS_ERR(lower_dentry)) {
+ err = PTR_ERR(lower_dentry);
+ goto out;
+ }
+ }
+
+ lower_parent_dentry = lock_parent(lower_dentry);
+ if (IS_ERR(lower_parent_dentry)) {
+ err = PTR_ERR(lower_parent_dentry);
+ goto out;
+ }
+
+ err = init_lower_nd(&lower_nd, LOOKUP_CREATE);
+ if (unlikely(err < 0))
+ goto out;
+ err = vfs_create(lower_parent_dentry->d_inode, lower_dentry, mode,
+ &lower_nd);
+ release_lower_nd(&lower_nd, err);
+
+ if (!err) {
+ err = PTR_ERR(unionfs_interpose(dentry, parent->i_sb, 0));
+ if (!err) {
+ unionfs_copy_attr_times(parent);
+ fsstack_copy_inode_size(parent,
+ lower_parent_dentry->d_inode);
+ /* update no. of links on parent directory */
+ parent->i_nlink = unionfs_get_nlinks(parent);
+ }
+ }
+
+ unlock_dir(lower_parent_dentry);
+
+out:
+ dput(wh_dentry);
+ kfree(name);
+
+ if (!err)
+ unionfs_postcopyup_setmnt(dentry);
+
+ unionfs_check_inode(parent);
+ if (!err) {
+ unionfs_check_dentry(dentry->d_parent);
+ unionfs_check_nd(nd);
+ }
+ unionfs_check_dentry(dentry);
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+ return err;
+}
+
+/*
+ * unionfs_lookup is the only special function which takes a dentry, yet we
+ * do NOT want to call __unionfs_d_revalidate_chain because by definition,
+ * we don't have a valid dentry here yet.
+ */
+static struct dentry *unionfs_lookup(struct inode *parent,
+ struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct path path_save;
+ struct dentry *ret;
+
+ unionfs_read_lock(dentry->d_sb);
+
+ /* save the dentry & vfsmnt from namei */
+ if (nd) {
+ path_save.dentry = nd->dentry;
+ path_save.mnt = nd->mnt;
+ }
+
+ /*
+ * unionfs_lookup_backend returns a locked dentry upon success,
+ * so we'll have to unlock it below.
+ */
+ ret = unionfs_lookup_backend(dentry, nd, INTERPOSE_LOOKUP);
+
+ /* restore the dentry & vfsmnt in namei */
+ if (nd) {
+ nd->dentry = path_save.dentry;
+ nd->mnt = path_save.mnt;
+ }
+ if (!IS_ERR(ret)) {
+ if (ret)
+ dentry = ret;
+ /* parent times may have changed */
+ unionfs_copy_attr_times(dentry->d_parent->d_inode);
+ }
+
+ unionfs_check_inode(parent);
+ unionfs_check_dentry(dentry);
+ unionfs_check_dentry(dentry->d_parent);
+ unionfs_check_nd(nd);
+ if (!IS_ERR(ret))
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+
+ return ret;
+}
+
+static int unionfs_link(struct dentry *old_dentry, struct inode *dir,
+ struct dentry *new_dentry)
+{
+ int err = 0;
+ struct dentry *lower_old_dentry = NULL;
+ struct dentry *lower_new_dentry = NULL;
+ struct dentry *lower_dir_dentry = NULL;
+ struct dentry *whiteout_dentry;
+ char *name = NULL;
+
+ unionfs_read_lock(old_dentry->d_sb);
+ unionfs_double_lock_dentry(new_dentry, old_dentry);
+
+ if (unlikely(!__unionfs_d_revalidate_chain(old_dentry, NULL, false))) {
+ err = -ESTALE;
+ goto out;
+ }
+ if (unlikely(new_dentry->d_inode &&
+ !__unionfs_d_revalidate_chain(new_dentry, NULL, false))) {
+ err = -ESTALE;
+ goto out;
+ }
+
+ lower_new_dentry = unionfs_lower_dentry(new_dentry);
+
+ /*
+ * check if whiteout exists in the branch of new dentry, i.e. lookup
+ * .wh.foo first. If present, delete it
+ */
+ name = alloc_whname(new_dentry->d_name.name, new_dentry->d_name.len);
+ if (unlikely(IS_ERR(name))) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry = lookup_one_len(name, lower_new_dentry->d_parent,
+ new_dentry->d_name.len +
+ UNIONFS_WHLEN);
+ if (IS_ERR(whiteout_dentry)) {
+ err = PTR_ERR(whiteout_dentry);
+ goto out;
+ }
+
+ if (!whiteout_dentry->d_inode) {
+ dput(whiteout_dentry);
+ whiteout_dentry = NULL;
+ } else {
+ /* found a .wh.foo entry, unlink it and then call vfs_link() */
+ lower_dir_dentry = lock_parent(whiteout_dentry);
+ err = is_robranch_super(new_dentry->d_sb, dbstart(new_dentry));
+ if (!err)
+ err = vfs_unlink(lower_dir_dentry->d_inode,
+ whiteout_dentry);
+
+ fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
+ dir->i_nlink = unionfs_get_nlinks(dir);
+ unlock_dir(lower_dir_dentry);
+ lower_dir_dentry = NULL;
+ dput(whiteout_dentry);
+ if (err)
+ goto out;
+ }
+
+ if (dbstart(old_dentry) != dbstart(new_dentry)) {
+ lower_new_dentry = create_parents(dir, new_dentry,
+ new_dentry->d_name.name,
+ dbstart(old_dentry));
+ err = PTR_ERR(lower_new_dentry);
+ if (IS_COPYUP_ERR(err))
+ goto docopyup;
+ if (!lower_new_dentry || IS_ERR(lower_new_dentry))
+ goto out;
+ }
+ lower_new_dentry = unionfs_lower_dentry(new_dentry);
+ lower_old_dentry = unionfs_lower_dentry(old_dentry);
+
+ BUG_ON(dbstart(old_dentry) != dbstart(new_dentry));
+ lower_dir_dentry = lock_parent(lower_new_dentry);
+ err = is_robranch(old_dentry);
+ if (!err)
+ err = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
+ lower_new_dentry);
+ unlock_dir(lower_dir_dentry);
+
+docopyup:
+ if (IS_COPYUP_ERR(err)) {
+ int old_bstart = dbstart(old_dentry);
+ int bindex;
+
+ for (bindex = old_bstart - 1; bindex >= 0; bindex--) {
+ err = copyup_dentry(old_dentry->d_parent->d_inode,
+ old_dentry, old_bstart,
+ bindex, old_dentry->d_name.name,
+ old_dentry->d_name.len, NULL,
+ i_size_read(old_dentry->d_inode));
+ if (!err) {
+ lower_new_dentry =
+ create_parents(dir, new_dentry,
+ new_dentry->d_name.name,
+ bindex);
+ lower_old_dentry =
+ unionfs_lower_dentry(old_dentry);
+ lower_dir_dentry =
+ lock_parent(lower_new_dentry);
+ /* do vfs_link */
+ err = vfs_link(lower_old_dentry,
+ lower_dir_dentry->d_inode,
+ lower_new_dentry);
+ unlock_dir(lower_dir_dentry);
+ goto check_link;
+ }
+ }
+ goto out;
+ }
+
+check_link:
+ if (err || !lower_new_dentry->d_inode)
+ goto out;
+
+ /* Its a hard link, so use the same inode */
+ new_dentry->d_inode = igrab(old_dentry->d_inode);
+ d_instantiate(new_dentry, new_dentry->d_inode);
+ unionfs_copy_attr_all(dir, lower_new_dentry->d_parent->d_inode);
+ fsstack_copy_inode_size(dir, lower_new_dentry->d_parent->d_inode);
+
+ /* propagate number of hard-links */
+ old_dentry->d_inode->i_nlink = unionfs_get_nlinks(old_dentry->d_inode);
+ /* new dentry's ctime may have changed due to hard-link counts */
+ unionfs_copy_attr_times(new_dentry->d_inode);
+
+out:
+ if (!new_dentry->d_inode)
+ d_drop(new_dentry);
+
+ kfree(name);
+ if (!err)
+ unionfs_postcopyup_setmnt(new_dentry);
+
+ unionfs_check_inode(dir);
+ unionfs_check_dentry(new_dentry);
+ unionfs_check_dentry(old_dentry);
+
+ unionfs_unlock_dentry(new_dentry);
+ unionfs_unlock_dentry(old_dentry);
+ unionfs_read_unlock(old_dentry->d_sb);
+
+ return err;
+}
+
+static int unionfs_symlink(struct inode *dir, struct dentry *dentry,
+ const char *symname)
+{
+ int err = 0;
+ struct dentry *lower_dentry = NULL;
+ struct dentry *whiteout_dentry = NULL;
+ struct dentry *lower_dir_dentry = NULL;
+ umode_t mode;
+ int bindex = 0, bstart;
+ char *name = NULL;
+
+ unionfs_read_lock(dentry->d_sb);
+ unionfs_lock_dentry(dentry);
+
+ if (unlikely(dentry->d_inode &&
+ !__unionfs_d_revalidate_chain(dentry, NULL, false))) {
+ err = -ESTALE;
+ goto out;
+ }
+
+ /* We start out in the leftmost branch. */
+ bstart = dbstart(dentry);
+
+ lower_dentry = unionfs_lower_dentry(dentry);
+
+ /*
+ * check if whiteout exists in this branch, i.e. lookup .wh.foo
+ * first. If present, delete it
+ */
+ name = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+ if (unlikely(IS_ERR(name))) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry =
+ lookup_one_len(name, lower_dentry->d_parent,
+ dentry->d_name.len + UNIONFS_WHLEN);
+ if (IS_ERR(whiteout_dentry)) {
+ err = PTR_ERR(whiteout_dentry);
+ goto out;
+ }
+
+ if (!whiteout_dentry->d_inode) {
+ dput(whiteout_dentry);
+ whiteout_dentry = NULL;
+ } else {
+ /*
+ * found a .wh.foo entry, unlink it and then call
+ * vfs_symlink().
+ */
+ lower_dir_dentry = lock_parent(whiteout_dentry);
+
+ err = is_robranch_super(dentry->d_sb, bstart);
+ if (!err)
+ err = vfs_unlink(lower_dir_dentry->d_inode,
+ whiteout_dentry);
+ dput(whiteout_dentry);
+
+ fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
+ /* propagate number of hard-links */
+ dir->i_nlink = unionfs_get_nlinks(dir);
+
+ unlock_dir(lower_dir_dentry);
+
+ if (err) {
+ /* exit if the error returned was NOT -EROFS */
+ if (!IS_COPYUP_ERR(err))
+ goto out;
+ /*
+ * should now try to create symlink in the another
+ * branch.
+ */
+ bstart--;
+ }
+ }
+
+ /*
+ * deleted whiteout if it was present, now do a normal vfs_symlink()
+ * with possible recursive directory creation
+ */
+ for (bindex = bstart; bindex >= 0; bindex--) {
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!lower_dentry) {
+ /*
+ * if lower_dentry is NULL, create the entire
+ * dentry directory structure in branch 'bindex'.
+ * lower_dentry will NOT be null when bindex ==
+ * bstart because lookup passed as a negative
+ * unionfs dentry pointing to a lone negative
+ * underlying dentry
+ */
+ lower_dentry = create_parents(dir, dentry,
+ dentry->d_name.name,
+ bindex);
+ if (!lower_dentry || IS_ERR(lower_dentry)) {
+ if (IS_ERR(lower_dentry))
+ err = PTR_ERR(lower_dentry);
+ if (!IS_COPYUP_ERR(err))
+ printk(KERN_ERR
+ "unionfs: create_parents for "
+ "symlink failed: bindex=%d "
+ "err=%d\n", bindex, err);
+ continue;
+ }
+ }
+
+ lower_dir_dentry = lock_parent(lower_dentry);
+
+ err = is_robranch_super(dentry->d_sb, bindex);
+ if (!err) {
+ mode = S_IALLUGO;
+ err = vfs_symlink(lower_dir_dentry->d_inode,
+ lower_dentry, symname, mode);
+ }
+ unlock_dir(lower_dir_dentry);
+
+ if (err || !lower_dentry->d_inode) {
+ /*
+ * break out of for loop if error returned was NOT
+ * -EROFS.
+ */
+ if (!IS_COPYUP_ERR(err))
+ break;
+ } else {
+ /*
+ * Only INTERPOSE_LOOKUP can return a value other
+ * than 0 on err.
+ */
+ err = PTR_ERR(unionfs_interpose(dentry,
+ dir->i_sb, 0));
+ if (!err) {
+ fsstack_copy_attr_times(dir,
+ lower_dir_dentry->
+ d_inode);
+ fsstack_copy_inode_size(dir,
+ lower_dir_dentry->
+ d_inode);
+ /*
+ * update number of links on parent
+ * directory.
+ */
+ dir->i_nlink = unionfs_get_nlinks(dir);
+ }
+ break;
+ }
+ }
+
+out:
+ if (!dentry->d_inode)
+ d_drop(dentry);
+
+ kfree(name);
+ if (!err)
+ unionfs_postcopyup_setmnt(dentry);
+
+ unionfs_check_inode(dir);
+ unionfs_check_dentry(dentry);
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+
+ return err;
+}
+
+static int unionfs_mkdir(struct inode *parent, struct dentry *dentry, int mode)
+{
+ int err = 0;
+ struct dentry *lower_dentry = NULL, *whiteout_dentry = NULL;
+ struct dentry *lower_parent_dentry = NULL;
+ int bindex = 0, bstart;
+ char *name = NULL;
+ int whiteout_unlinked = 0;
+ struct sioq_args args;
+
+ unionfs_read_lock(dentry->d_sb);
+ unionfs_lock_dentry(dentry);
+
+ if (unlikely(dentry->d_inode &&
+ !__unionfs_d_revalidate_chain(dentry, NULL, false))) {
+ err = -ESTALE;
+ goto out;
+ }
+
+ bstart = dbstart(dentry);
+
+ lower_dentry = unionfs_lower_dentry(dentry);
+
+ /*
+ * check if whiteout exists in this branch, i.e. lookup .wh.foo
+ * first.
+ */
+ name = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+ if (unlikely(IS_ERR(name))) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry = lookup_one_len(name, lower_dentry->d_parent,
+ dentry->d_name.len + UNIONFS_WHLEN);
+ if (IS_ERR(whiteout_dentry)) {
+ err = PTR_ERR(whiteout_dentry);
+ goto out;
+ }
+
+ if (!whiteout_dentry->d_inode) {
+ dput(whiteout_dentry);
+ whiteout_dentry = NULL;
+ } else {
+ lower_parent_dentry = lock_parent(whiteout_dentry);
+
+ /* found a.wh.foo entry, remove it then do vfs_mkdir */
+ err = is_robranch_super(dentry->d_sb, bstart);
+ if (!err) {
+ args.unlink.parent = lower_parent_dentry->d_inode;
+ args.unlink.dentry = whiteout_dentry;
+ run_sioq(__unionfs_unlink, &args);
+ err = args.err;
+ }
+ dput(whiteout_dentry);
+
+ unlock_dir(lower_parent_dentry);
+
+ if (err) {
+ /* exit if the error returned was NOT -EROFS */
+ if (!IS_COPYUP_ERR(err))
+ goto out;
+ bstart--;
+ } else {
+ whiteout_unlinked = 1;
+ }
+ }
+
+ for (bindex = bstart; bindex >= 0; bindex--) {
+ int i;
+ int bend = dbend(dentry);
+
+ if (is_robranch_super(dentry->d_sb, bindex))
+ continue;
+
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!lower_dentry) {
+ lower_dentry = create_parents(parent, dentry,
+ dentry->d_name.name,
+ bindex);
+ if (!lower_dentry || IS_ERR(lower_dentry)) {
+ printk(KERN_ERR "unionfs: lower dentry "
+ " NULL for bindex = %d\n", bindex);
+ continue;
+ }
+ }
+
+ lower_parent_dentry = lock_parent(lower_dentry);
+
+ if (IS_ERR(lower_parent_dentry)) {
+ err = PTR_ERR(lower_parent_dentry);
+ goto out;
+ }
+
+ err = vfs_mkdir(lower_parent_dentry->d_inode, lower_dentry,
+ mode);
+
+ unlock_dir(lower_parent_dentry);
+
+ /* did the mkdir succeed? */
+ if (err)
+ break;
+
+ for (i = bindex + 1; i < bend; i++) {
+ if (unionfs_lower_dentry_idx(dentry, i)) {
+ dput(unionfs_lower_dentry_idx(dentry, i));
+ unionfs_set_lower_dentry_idx(dentry, i, NULL);
+ }
+ }
+ set_dbend(dentry, bindex);
+
+ /*
+ * Only INTERPOSE_LOOKUP can return a value other than 0 on
+ * err.
+ */
+ err = PTR_ERR(unionfs_interpose(dentry, parent->i_sb, 0));
+ if (!err) {
+ unionfs_copy_attr_times(parent);
+ fsstack_copy_inode_size(parent,
+ lower_parent_dentry->d_inode);
+
+ /* update number of links on parent directory */
+ parent->i_nlink = unionfs_get_nlinks(parent);
+ }
+
+ err = make_dir_opaque(dentry, dbstart(dentry));
+ if (err) {
+ printk(KERN_ERR "unionfs: mkdir: error creating "
+ ".wh.__dir_opaque: %d\n", err);
+ goto out;
+ }
+
+ /* we are done! */
+ break;
+ }
+
+out:
+ if (!dentry->d_inode)
+ d_drop(dentry);
+
+ kfree(name);
+
+ if (!err) {
+ unionfs_copy_attr_times(dentry->d_inode);
+ unionfs_postcopyup_setmnt(dentry);
+ }
+ unionfs_check_inode(parent);
+ unionfs_check_dentry(dentry);
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+
+ return err;
+}
+
+static int unionfs_mknod(struct inode *dir, struct dentry *dentry, int mode,
+ dev_t dev)
+{
+ int err = 0;
+ struct dentry *lower_dentry = NULL, *whiteout_dentry = NULL;
+ struct dentry *lower_parent_dentry = NULL;
+ int bindex = 0, bstart;
+ char *name = NULL;
+ int whiteout_unlinked = 0;
+
+ unionfs_read_lock(dentry->d_sb);
+ unionfs_lock_dentry(dentry);
+
+ if (unlikely(dentry->d_inode &&
+ !__unionfs_d_revalidate_chain(dentry, NULL, false))) {
+ err = -ESTALE;
+ goto out;
+ }
+
+ bstart = dbstart(dentry);
+
+ lower_dentry = unionfs_lower_dentry(dentry);
+
+ /*
+ * check if whiteout exists in this branch, i.e. lookup .wh.foo
+ * first.
+ */
+ name = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+ if (unlikely(IS_ERR(name))) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry = lookup_one_len(name, lower_dentry->d_parent,
+ dentry->d_name.len + UNIONFS_WHLEN);
+ if (IS_ERR(whiteout_dentry)) {
+ err = PTR_ERR(whiteout_dentry);
+ goto out;
+ }
+
+ if (!whiteout_dentry->d_inode) {
+ dput(whiteout_dentry);
+ whiteout_dentry = NULL;
+ } else {
+ /* found .wh.foo, unlink it */
+ lower_parent_dentry = lock_parent(whiteout_dentry);
+
+ /* found a.wh.foo entry, remove it then do vfs_mkdir */
+ err = is_robranch_super(dentry->d_sb, bstart);
+ if (!err)
+ err = vfs_unlink(lower_parent_dentry->d_inode,
+ whiteout_dentry);
+ dput(whiteout_dentry);
+
+ unlock_dir(lower_parent_dentry);
+
+ if (err) {
+ if (!IS_COPYUP_ERR(err))
+ goto out;
+ bstart--;
+ } else {
+ whiteout_unlinked = 1;
+ }
+ }
+
+ for (bindex = bstart; bindex >= 0; bindex--) {
+ if (is_robranch_super(dentry->d_sb, bindex))
+ continue;
+
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!lower_dentry) {
+ lower_dentry = create_parents(dir, dentry,
+ dentry->d_name.name,
+ bindex);
+ if (IS_ERR(lower_dentry)) {
+ printk(KERN_ERR "unionfs: failed to create "
+ "parents on %d, err = %ld\n",
+ bindex, PTR_ERR(lower_dentry));
+ continue;
+ }
+ }
+
+ lower_parent_dentry = lock_parent(lower_dentry);
+ if (IS_ERR(lower_parent_dentry)) {
+ err = PTR_ERR(lower_parent_dentry);
+ goto out;
+ }
+
+ err = vfs_mknod(lower_parent_dentry->d_inode,
+ lower_dentry, mode, dev);
+
+ if (err) {
+ unlock_dir(lower_parent_dentry);
+ break;
+ }
+
+ /*
+ * Only INTERPOSE_LOOKUP can return a value other than 0 on
+ * err.
+ */
+ err = PTR_ERR(unionfs_interpose(dentry, dir->i_sb, 0));
+ if (!err) {
+ fsstack_copy_attr_times(dir,
+ lower_parent_dentry->d_inode);
+ fsstack_copy_inode_size(dir,
+ lower_parent_dentry->d_inode);
+ /* update number of links on parent directory */
+ dir->i_nlink = unionfs_get_nlinks(dir);
+ }
+ unlock_dir(lower_parent_dentry);
+
+ break;
+ }
+
+out:
+ if (!dentry->d_inode)
+ d_drop(dentry);
+
+ kfree(name);
+
+ if (!err)
+ unionfs_postcopyup_setmnt(dentry);
+
+ unionfs_check_inode(dir);
+ unionfs_check_dentry(dentry);
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+
+ return err;
+}
+
+static int unionfs_readlink(struct dentry *dentry, char __user *buf,
+ int bufsiz)
+{
+ int err;
+ struct dentry *lower_dentry;
+
+ unionfs_read_lock(dentry->d_sb);
+ unionfs_lock_dentry(dentry);
+
+ if (unlikely(!__unionfs_d_revalidate_chain(dentry, NULL, false))) {
+ err = -ESTALE;
+ goto out;
+ }
+
+ lower_dentry = unionfs_lower_dentry(dentry);
+
+ if (!lower_dentry->d_inode->i_op ||
+ !lower_dentry->d_inode->i_op->readlink) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = lower_dentry->d_inode->i_op->readlink(lower_dentry,
+ buf, bufsiz);
+ if (err > 0)
+ fsstack_copy_attr_atime(dentry->d_inode,
+ lower_dentry->d_inode);
+
+out:
+ unionfs_check_dentry(dentry);
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+
+ return err;
+}
+
+/*
+ * unionfs_follow_link takes a dentry, but it is simple. It only needs to
+ * allocate some memory and then call our ->readlink method. Our
+ * unionfs_readlink *does* lock our dentry and revalidate the dentry.
+ * Therefore, we do not have to lock our dentry here, to prevent a deadlock;
+ * nor do we need to revalidate it either. It is safe to not lock our
+ * dentry here, nor revalidate it, because unionfs_follow_link does not do
+ * anything (prior to calling ->readlink) which could become inconsistent
+ * due to branch management.
+ */
+static void *unionfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ char *buf;
+ int len = PAGE_SIZE, err;
+ mm_segment_t old_fs;
+
+ unionfs_read_lock(dentry->d_sb);
+
+ /* This is freed by the put_link method assuming a successful call. */
+ buf = kmalloc(len, GFP_KERNEL);
+ if (unlikely(!buf)) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ /* read the symlink, and then we will follow it */
+ old_fs = get_fs();
+ set_fs(KERNEL_DS);
+ err = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
+ set_fs(old_fs);
+ if (err < 0) {
+ kfree(buf);
+ buf = NULL;
+ goto out;
+ }
+ buf[err] = 0;
+ nd_set_link(nd, buf);
+ err = 0;
+
+out:
+ unionfs_check_dentry(dentry);
+ unionfs_check_nd(nd);
+ unionfs_read_unlock(dentry->d_sb);
+ return ERR_PTR(err);
+}
+
+/* FIXME: We may not have to lock here */
+static void unionfs_put_link(struct dentry *dentry, struct nameidata *nd,
+ void *cookie)
+{
+ unionfs_read_lock(dentry->d_sb);
+
+ unionfs_lock_dentry(dentry);
+ if (unlikely(!__unionfs_d_revalidate_chain(dentry, nd, false)))
+ printk(KERN_ERR
+ "unionfs: put_link failed to revalidate dentry\n");
+
+ unionfs_check_dentry(dentry);
+ unionfs_check_nd(nd);
+ kfree(nd_get_link(nd));
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+}
+
+/*
+ * Don't grab the superblock read-lock in unionfs_permission, which prevents
+ * a deadlock with the branch-management "add branch" code (which grabbed
+ * the write lock). It is safe to not grab the read lock here, because even
+ * with branch management taking place, there is no chance that
+ * unionfs_permission, or anything it calls, will use stale branch
+ * information.
+ */
+static int unionfs_permission(struct inode *inode, int mask,
+ struct nameidata *nd)
+{
+ struct inode *lower_inode = NULL;
+ int err = 0;
+ int bindex, bstart, bend;
+ const int is_file = !S_ISDIR(inode->i_mode);
+ const int write_mask = (mask & MAY_WRITE) && !(mask & MAY_READ);
+
+ bstart = ibstart(inode);
+ bend = ibend(inode);
+ if (unlikely(bstart < 0 || bend < 0)) {
+ /*
+ * With branch-management, we can get a stale inode here.
+ * If so, we return ESTALE back to link_path_walk, which
+ * would discard the dcache entry and re-lookup the
+ * dentry+inode. This should be equivalent to issuing
+ * __unionfs_d_revalidate_chain on nd.dentry here.
+ */
+ if (is_file) /* dirs can be unlinked but chdir'ed to */
+ err = -ESTALE; /* force revalidate */
+ goto out;
+ }
+
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ lower_inode = unionfs_lower_inode_idx(inode, bindex);
+ if (!lower_inode)
+ continue;
+
+ /*
+ * check the condition for D-F-D underlying files/directories,
+ * we don't have to check for files, if we are checking for
+ * directories.
+ */
+ if (!is_file && !S_ISDIR(lower_inode->i_mode))
+ continue;
+
+ /*
+ * We check basic permissions, but we ignore any conditions
+ * such as readonly file systems or branches marked as
+ * readonly, because those conditions should lead to a
+ * copyup taking place later on.
+ */
+ err = permission(lower_inode, mask, nd);
+ if (err && bindex > 0) {
+ umode_t mode = lower_inode->i_mode;
+ if (is_robranch_super(inode->i_sb, bindex) &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ err = 0;
+ if (IS_COPYUP_ERR(err))
+ err = 0;
+ }
+
+ /*
+ * The permissions are an intersection of the overall directory
+ * permissions, so we fail if one fails.
+ */
+ if (err)
+ goto out;
+
+ /* only the leftmost file matters. */
+ if (is_file || write_mask) {
+ if (is_file && write_mask) {
+ err = get_write_access(lower_inode);
+ if (!err)
+ put_write_access(lower_inode);
+ }
+ break;
+ }
+ }
+ /* sync times which may have changed (asynchronously) below */
+ unionfs_copy_attr_times(inode);
+
+out:
+ unionfs_check_inode(inode);
+ unionfs_check_nd(nd);
+ return err;
+}
+
+static int unionfs_setattr(struct dentry *dentry, struct iattr *ia)
+{
+ int err = 0;
+ struct dentry *lower_dentry;
+ struct inode *inode = NULL;
+ struct inode *lower_inode = NULL;
+ int bstart, bend, bindex;
+ int i;
+ int copyup = 0;
+
+ unionfs_read_lock(dentry->d_sb);
+ unionfs_lock_dentry(dentry);
+
+ if (unlikely(!__unionfs_d_revalidate_chain(dentry, NULL, false))) {
+ err = -ESTALE;
+ goto out;
+ }
+
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+ inode = dentry->d_inode;
+
+ /*
+ * mode change is for clearing setuid/setgid. Allow lower filesystem
+ * to reinterpret it in its own way.
+ */
+ if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
+ ia->ia_valid &= ~ATTR_MODE;
+
+ for (bindex = bstart; (bindex <= bend) || (bindex == bstart);
+ bindex++) {
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!lower_dentry)
+ continue;
+ BUG_ON(lower_dentry->d_inode == NULL);
+
+ /* If the file is on a read only branch */
+ if (is_robranch_super(dentry->d_sb, bindex)
+ || IS_RDONLY(lower_dentry->d_inode)) {
+ if (copyup || (bindex != bstart))
+ continue;
+ /* Only if its the leftmost file, copyup the file */
+ for (i = bstart - 1; i >= 0; i--) {
+ loff_t size = i_size_read(dentry->d_inode);
+ if (ia->ia_valid & ATTR_SIZE)
+ size = ia->ia_size;
+ err = copyup_dentry(dentry->d_parent->d_inode,
+ dentry, bstart, i,
+ dentry->d_name.name,
+ dentry->d_name.len,
+ NULL, size);
+
+ if (!err) {
+ copyup = 1;
+ lower_dentry =
+ unionfs_lower_dentry(dentry);
+ break;
+ }
+ /*
+ * if error is in the leftmost branch, pass
+ * it up.
+ */
+ if (i == 0)
+ goto out;
+ }
+
+ }
+ err = notify_change(lower_dentry, ia);
+ if (err)
+ goto out;
+ break;
+ }
+
+ /* for mmap */
+ if (ia->ia_valid & ATTR_SIZE) {
+ if (ia->ia_size != i_size_read(inode)) {
+ err = vmtruncate(inode, ia->ia_size);
+ if (err)
+ printk(KERN_ERR
+ "unionfs: setattr: vmtruncate failed\n");
+ }
+ }
+
+ /* get the size from the first lower inode */
+ lower_inode = unionfs_lower_inode(inode);
+ unionfs_copy_attr_all(inode, lower_inode);
+ /*
+ * unionfs_copy_attr_all will copy the lower times to our inode if
+ * the lower ones are newer (useful for cache coherency). However,
+ * ->setattr is the only place in which we may have to copy the
+ * lower inode times absolutely, to support utimes(2).
+ */
+ if (ia->ia_valid & ATTR_MTIME_SET)
+ inode->i_mtime = lower_inode->i_mtime;
+ if (ia->ia_valid & ATTR_CTIME)
+ inode->i_ctime = lower_inode->i_ctime;
+ if (ia->ia_valid & ATTR_ATIME_SET)
+ inode->i_atime = lower_inode->i_atime;
+ fsstack_copy_inode_size(inode, lower_inode);
+ /* if setattr succeeded, then parent dir may have changed */
+ unionfs_copy_attr_times(dentry->d_parent->d_inode);
+out:
+ unionfs_check_dentry(dentry);
+ unionfs_check_dentry(dentry->d_parent);
+ unionfs_unlock_dentry(dentry);
+ unionfs_read_unlock(dentry->d_sb);
+
+ return err;
+}
+
+struct inode_operations unionfs_symlink_iops = {
+ .readlink = unionfs_readlink,
+ .permission = unionfs_permission,
+ .follow_link = unionfs_follow_link,
+ .setattr = unionfs_setattr,
+ .put_link = unionfs_put_link,
+};
+
+struct inode_operations unionfs_dir_iops = {
+ .create = unionfs_create,
+ .lookup = unionfs_lookup,
+ .link = unionfs_link,
+ .unlink = unionfs_unlink,
+ .symlink = unionfs_symlink,
+ .mkdir = unionfs_mkdir,
+ .rmdir = unionfs_rmdir,
+ .mknod = unionfs_mknod,
+ .rename = unionfs_rename,
+ .permission = unionfs_permission,
+ .setattr = unionfs_setattr,
+#ifdef CONFIG_UNION_FS_XATTR
+ .setxattr = unionfs_setxattr,
+ .getxattr = unionfs_getxattr,
+ .removexattr = unionfs_removexattr,
+ .listxattr = unionfs_listxattr,
+#endif /* CONFIG_UNION_FS_XATTR */
+};
+
+struct inode_operations unionfs_main_iops = {
+ .permission = unionfs_permission,
+ .setattr = unionfs_setattr,
+#ifdef CONFIG_UNION_FS_XATTR
+ .setxattr = unionfs_setxattr,
+ .getxattr = unionfs_getxattr,
+ .removexattr = unionfs_removexattr,
+ .listxattr = unionfs_listxattr,
+#endif /* CONFIG_UNION_FS_XATTR */
+};
--
1.5.2.2


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