From: Erez Zadok <ezk@cs.sunysb.edu>
To: torvalds@linux-foundation.org, akpm@linux-foundation.org,
       hch@infradead.org, viro@ftp.linux.org.uk
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
       Erez Zadok <ezk@cs.sunysb.edu>
Subject: [PATCH 12/29] Unionfs: rename method and helpers
Date: Thu, 10 Jan 2008 09:59:31 -0500
Message-Id: <11999771943311-git-send-email-ezk@cs.sunysb.edu>
In-Reply-To: <11999771882152-git-send-email-ezk@cs.sunysb.edu>
References: <11999771882152-git-send-email-ezk@cs.sunysb.edu>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 15519
Lines: 551

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
 fs/unionfs/rename.c |  531 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 531 insertions(+), 0 deletions(-)
 create mode 100644 fs/unionfs/rename.c

diff --git a/fs/unionfs/rename.c b/fs/unionfs/rename.c
new file mode 100644
index 0000000..9306a2b
--- /dev/null
+++ b/fs/unionfs/rename.c
@@ -0,0 +1,531 @@
+/*
+ * 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_rename(struct inode *old_dir, struct dentry *old_dentry,
+			    struct inode *new_dir, struct dentry *new_dentry,
+			    int bindex, struct dentry **wh_old)
+{
+	int err = 0;
+	struct dentry *lower_old_dentry;
+	struct dentry *lower_new_dentry;
+	struct dentry *lower_old_dir_dentry;
+	struct dentry *lower_new_dir_dentry;
+	struct dentry *lower_wh_dentry;
+	struct dentry *lower_wh_dir_dentry;
+	char *wh_name = NULL;
+
+	lower_new_dentry = unionfs_lower_dentry_idx(new_dentry, bindex);
+	lower_old_dentry = unionfs_lower_dentry_idx(old_dentry, bindex);
+
+	if (!lower_new_dentry) {
+		lower_new_dentry =
+			create_parents(new_dentry->d_parent->d_inode,
+				       new_dentry, new_dentry->d_name.name,
+				       bindex);
+		if (IS_ERR(lower_new_dentry)) {
+			err = PTR_ERR(lower_new_dentry);
+			if (IS_COPYUP_ERR(err))
+				goto out;
+			printk(KERN_ERR "unionfs: error creating directory "
+			       "tree for rename, bindex=%d err=%d\n",
+			       bindex, err);
+			goto out;
+		}
+	}
+
+	wh_name = alloc_whname(new_dentry->d_name.name,
+			       new_dentry->d_name.len);
+	if (unlikely(IS_ERR(wh_name))) {
+		err = PTR_ERR(wh_name);
+		goto out;
+	}
+
+	lower_wh_dentry = lookup_one_len(wh_name, lower_new_dentry->d_parent,
+					 new_dentry->d_name.len +
+					 UNIONFS_WHLEN);
+	if (IS_ERR(lower_wh_dentry)) {
+		err = PTR_ERR(lower_wh_dentry);
+		goto out;
+	}
+
+	if (lower_wh_dentry->d_inode) {
+		/* get rid of the whiteout that is existing */
+		if (lower_new_dentry->d_inode) {
+			printk(KERN_ERR "unionfs: both a whiteout and a "
+			       "dentry exist when doing a rename!\n");
+			err = -EIO;
+
+			dput(lower_wh_dentry);
+			goto out;
+		}
+
+		lower_wh_dir_dentry = lock_parent_wh(lower_wh_dentry);
+		err = is_robranch_super(old_dentry->d_sb, bindex);
+		if (!err)
+			err = vfs_unlink(lower_wh_dir_dentry->d_inode,
+					 lower_wh_dentry);
+
+		dput(lower_wh_dentry);
+		unlock_dir(lower_wh_dir_dentry);
+		if (err)
+			goto out;
+	} else {
+		dput(lower_wh_dentry);
+	}
+
+	err = is_robranch_super(old_dentry->d_sb, bindex);
+	if (err)
+		goto out;
+
+	dget(lower_old_dentry);
+	lower_old_dir_dentry = dget_parent(lower_old_dentry);
+	lower_new_dir_dentry = dget_parent(lower_new_dentry);
+
+	/*
+	 * ready to whiteout for old_dentry. caller will create the actual
+	 * whiteout, and must dput(*wh_old)
+	 */
+	if (wh_old) {
+		char *whname;
+		whname = alloc_whname(old_dentry->d_name.name,
+				      old_dentry->d_name.len);
+		err = PTR_ERR(whname);
+		if (unlikely(IS_ERR(whname)))
+			goto out_dput;
+		*wh_old = lookup_one_len(whname, lower_old_dir_dentry,
+					 old_dentry->d_name.len +
+					 UNIONFS_WHLEN);
+		kfree(whname);
+		err = PTR_ERR(*wh_old);
+		if (IS_ERR(*wh_old)) {
+			*wh_old = NULL;
+			goto out_dput;
+		}
+	}
+
+	/* see Documentation/filesystems/unionfs/issues.txt */
+	lockdep_off();
+	lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+	err = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
+			 lower_new_dir_dentry->d_inode, lower_new_dentry);
+	unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+	lockdep_on();
+
+out_dput:
+	dput(lower_old_dir_dentry);
+	dput(lower_new_dir_dentry);
+	dput(lower_old_dentry);
+
+out:
+	if (!err) {
+		/* Fixup the new_dentry. */
+		if (bindex < dbstart(new_dentry))
+			set_dbstart(new_dentry, bindex);
+		else if (bindex > dbend(new_dentry))
+			set_dbend(new_dentry, bindex);
+	}
+
+	kfree(wh_name);
+
+	return err;
+}
+
+/*
+ * Main rename code.  This is sufficiently complex, that it's documented in
+ * Documentation/filesystems/unionfs/rename.txt.  This routine calls
+ * __unionfs_rename() above to perform some of the work.
+ */
+static int do_unionfs_rename(struct inode *old_dir,
+			     struct dentry *old_dentry,
+			     struct inode *new_dir,
+			     struct dentry *new_dentry)
+{
+	int err = 0;
+	int bindex, bwh_old;
+	int old_bstart, old_bend;
+	int new_bstart, new_bend;
+	int do_copyup = -1;
+	struct dentry *parent_dentry;
+	int local_err = 0;
+	int eio = 0;
+	int revert = 0;
+	struct dentry *wh_old = NULL;
+
+	old_bstart = dbstart(old_dentry);
+	bwh_old = old_bstart;
+	old_bend = dbend(old_dentry);
+	parent_dentry = old_dentry->d_parent;
+
+	new_bstart = dbstart(new_dentry);
+	new_bend = dbend(new_dentry);
+
+	/* Rename source to destination. */
+	err = __unionfs_rename(old_dir, old_dentry, new_dir, new_dentry,
+			       old_bstart, &wh_old);
+	if (err) {
+		if (!IS_COPYUP_ERR(err))
+			goto out;
+		do_copyup = old_bstart - 1;
+	} else {
+		revert = 1;
+	}
+
+	/*
+	 * Unlink all instances of destination that exist to the left of
+	 * bstart of source. On error, revert back, goto out.
+	 */
+	for (bindex = old_bstart - 1; bindex >= new_bstart; bindex--) {
+		struct dentry *unlink_dentry;
+		struct dentry *unlink_dir_dentry;
+
+		unlink_dentry = unionfs_lower_dentry_idx(new_dentry, bindex);
+		if (!unlink_dentry)
+			continue;
+
+		unlink_dir_dentry = lock_parent(unlink_dentry);
+		err = is_robranch_super(old_dir->i_sb, bindex);
+		if (!err)
+			err = vfs_unlink(unlink_dir_dentry->d_inode,
+					 unlink_dentry);
+
+		fsstack_copy_attr_times(new_dentry->d_parent->d_inode,
+					unlink_dir_dentry->d_inode);
+		/* propagate number of hard-links */
+		new_dentry->d_parent->d_inode->i_nlink =
+			unionfs_get_nlinks(new_dentry->d_parent->d_inode);
+
+		unlock_dir(unlink_dir_dentry);
+		if (!err) {
+			if (bindex != new_bstart) {
+				dput(unlink_dentry);
+				unionfs_set_lower_dentry_idx(new_dentry,
+							     bindex, NULL);
+			}
+		} else if (IS_COPYUP_ERR(err)) {
+			do_copyup = bindex - 1;
+		} else if (revert) {
+			dput(wh_old);
+			goto revert;
+		}
+	}
+
+	if (do_copyup != -1) {
+		for (bindex = do_copyup; bindex >= 0; bindex--) {
+			/*
+			 * copyup the file into some left directory, so that
+			 * you can rename it
+			 */
+			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 copyup failed, try next branch to the left */
+			if (err)
+				continue;
+			dput(wh_old);
+			bwh_old = bindex;
+			err = __unionfs_rename(old_dir, old_dentry,
+					       new_dir, new_dentry,
+					       bindex, &wh_old);
+			break;
+		}
+	}
+
+	/* make it opaque */
+	if (S_ISDIR(old_dentry->d_inode->i_mode)) {
+		err = make_dir_opaque(old_dentry, dbstart(old_dentry));
+		if (err)
+			goto revert;
+	}
+
+	/*
+	 * Create whiteout for source, only if:
+	 * (1) There is more than one underlying instance of source.
+	 * (2) We did a copy_up
+	 */
+	if ((old_bstart != old_bend) || (do_copyup != -1)) {
+		struct dentry *lower_parent;
+		struct nameidata nd;
+		if (!wh_old || wh_old->d_inode || bwh_old < 0) {
+			printk(KERN_ERR "unionfs: rename error "
+			       "(wh_old=%p/%p bwh_old=%d)\n", wh_old,
+			       (wh_old ? wh_old->d_inode : NULL), bwh_old);
+			err = -EIO;
+			goto out;
+		}
+		err = init_lower_nd(&nd, LOOKUP_CREATE);
+		if (unlikely(err < 0))
+			goto out;
+		lower_parent = lock_parent_wh(wh_old);
+		local_err = vfs_create(lower_parent->d_inode, wh_old, S_IRUGO,
+				       &nd);
+		unlock_dir(lower_parent);
+		if (!local_err) {
+			set_dbopaque(old_dentry, bwh_old);
+		} else {
+			/*
+			 * we can't fix anything now, so we cop-out and use
+			 * -EIO.
+			 */
+			printk(KERN_ERR "unionfs: can't create a whiteout for "
+			       "the source in rename!\n");
+			err = -EIO;
+		}
+		release_lower_nd(&nd, local_err);
+	}
+
+out:
+	dput(wh_old);
+	return err;
+
+revert:
+	/* Do revert here. */
+	local_err = unionfs_refresh_lower_dentry(new_dentry, old_bstart);
+	if (local_err) {
+		printk(KERN_ERR "unionfs: revert failed in rename: "
+		       "the new refresh failed\n");
+		eio = -EIO;
+	}
+
+	local_err = unionfs_refresh_lower_dentry(old_dentry, old_bstart);
+	if (local_err) {
+		printk(KERN_ERR "unionfs: revert failed in rename: "
+		       "the old refresh failed\n");
+		eio = -EIO;
+		goto revert_out;
+	}
+
+	if (!unionfs_lower_dentry_idx(new_dentry, bindex) ||
+	    !unionfs_lower_dentry_idx(new_dentry, bindex)->d_inode) {
+		printk(KERN_ERR "unionfs: revert failed in rename: "
+		       "the object disappeared from under us!\n");
+		eio = -EIO;
+		goto revert_out;
+	}
+
+	if (unionfs_lower_dentry_idx(old_dentry, bindex) &&
+	    unionfs_lower_dentry_idx(old_dentry, bindex)->d_inode) {
+		printk(KERN_ERR "unionfs: revert failed in rename: "
+		       "the object was created underneath us!\n");
+		eio = -EIO;
+		goto revert_out;
+	}
+
+	local_err = __unionfs_rename(new_dir, new_dentry,
+				     old_dir, old_dentry, old_bstart, NULL);
+
+	/* If we can't fix it, then we cop-out with -EIO. */
+	if (local_err) {
+		printk(KERN_ERR "unionfs: revert failed in rename!\n");
+		eio = -EIO;
+	}
+
+	local_err = unionfs_refresh_lower_dentry(new_dentry, bindex);
+	if (local_err)
+		eio = -EIO;
+	local_err = unionfs_refresh_lower_dentry(old_dentry, bindex);
+	if (local_err)
+		eio = -EIO;
+
+revert_out:
+	if (eio)
+		err = eio;
+	return err;
+}
+
+static struct dentry *lookup_whiteout(struct dentry *dentry)
+{
+	char *whname;
+	int bindex = -1, bstart = -1, bend = -1;
+	struct dentry *parent, *lower_parent, *wh_dentry;
+
+	whname = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+	if (unlikely(IS_ERR(whname)))
+		return (void *)whname;
+
+	parent = dget_parent(dentry);
+	unionfs_lock_dentry(parent, UNIONFS_DMUTEX_WHITEOUT);
+	bstart = dbstart(parent);
+	bend = dbend(parent);
+	wh_dentry = ERR_PTR(-ENOENT);
+	for (bindex = bstart; bindex <= bend; bindex++) {
+		lower_parent = unionfs_lower_dentry_idx(parent, bindex);
+		if (!lower_parent)
+			continue;
+		wh_dentry = lookup_one_len(whname, lower_parent,
+					   dentry->d_name.len + UNIONFS_WHLEN);
+		if (IS_ERR(wh_dentry))
+			continue;
+		if (wh_dentry->d_inode)
+			break;
+		dput(wh_dentry);
+		wh_dentry = ERR_PTR(-ENOENT);
+	}
+	unionfs_unlock_dentry(parent);
+	dput(parent);
+	kfree(whname);
+	return wh_dentry;
+}
+
+/*
+ * We can't copyup a directory, because it may involve huge numbers of
+ * children, etc.  Doing that in the kernel would be bad, so instead we
+ * return EXDEV to the user-space utility that caused this, and let the
+ * user-space recurse and ask us to copy up each file separately.
+ */
+static int may_rename_dir(struct dentry *dentry)
+{
+	int err, bstart;
+
+	err = check_empty(dentry, NULL);
+	if (err == -ENOTEMPTY) {
+		if (is_robranch(dentry))
+			return -EXDEV;
+	} else if (err) {
+		return err;
+	}
+
+	bstart = dbstart(dentry);
+	if (dbend(dentry) == bstart || dbopaque(dentry) == bstart)
+		return 0;
+
+	set_dbstart(dentry, bstart + 1);
+	err = check_empty(dentry, NULL);
+	set_dbstart(dentry, bstart);
+	if (err == -ENOTEMPTY)
+		err = -EXDEV;
+	return err;
+}
+
+int unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+		   struct inode *new_dir, struct dentry *new_dentry)
+{
+	int err = 0;
+	struct dentry *wh_dentry;
+
+	unionfs_read_lock(old_dentry->d_sb, UNIONFS_SMUTEX_CHILD);
+	unionfs_double_lock_dentry(old_dentry, new_dentry);
+
+	if (unlikely(!__unionfs_d_revalidate_chain(old_dentry, NULL, false))) {
+		err = -ESTALE;
+		goto out;
+	}
+	if (unlikely(!d_deleted(new_dentry) && new_dentry->d_inode &&
+		     !__unionfs_d_revalidate_chain(new_dentry, NULL, false))) {
+		err = -ESTALE;
+		goto out;
+	}
+
+	if (!S_ISDIR(old_dentry->d_inode->i_mode))
+		err = unionfs_partial_lookup(old_dentry);
+	else
+		err = may_rename_dir(old_dentry);
+
+	if (err)
+		goto out;
+
+	err = unionfs_partial_lookup(new_dentry);
+	if (err)
+		goto out;
+
+	/*
+	 * if new_dentry is already lower because of whiteout,
+	 * simply override it even if the whited-out dir is not empty.
+	 */
+	wh_dentry = lookup_whiteout(new_dentry);
+	if (!IS_ERR(wh_dentry)) {
+		dput(wh_dentry);
+	} else if (new_dentry->d_inode) {
+		if (S_ISDIR(old_dentry->d_inode->i_mode) !=
+		    S_ISDIR(new_dentry->d_inode->i_mode)) {
+			err = S_ISDIR(old_dentry->d_inode->i_mode) ?
+				-ENOTDIR : -EISDIR;
+			goto out;
+		}
+
+		if (S_ISDIR(new_dentry->d_inode->i_mode)) {
+			struct unionfs_dir_state *namelist = NULL;
+			/* check if this unionfs directory is empty or not */
+			err = check_empty(new_dentry, &namelist);
+			if (err)
+				goto out;
+
+			if (!is_robranch(new_dentry))
+				err = delete_whiteouts(new_dentry,
+						       dbstart(new_dentry),
+						       namelist);
+
+			free_rdstate(namelist);
+
+			if (err)
+				goto out;
+		}
+	}
+
+	err = do_unionfs_rename(old_dir, old_dentry, new_dir, new_dentry);
+	if (err)
+		goto out;
+
+	/*
+	 * force re-lookup since the dir on ro branch is not renamed, and
+	 * lower dentries still indicate the un-renamed ones.
+	 */
+	if (S_ISDIR(old_dentry->d_inode->i_mode))
+		atomic_dec(&UNIONFS_D(old_dentry)->generation);
+	else
+		unionfs_postcopyup_release(old_dentry);
+	if (new_dentry->d_inode && !S_ISDIR(new_dentry->d_inode->i_mode)) {
+		unionfs_postcopyup_release(new_dentry);
+		unionfs_postcopyup_setmnt(new_dentry);
+		if (!unionfs_lower_inode(new_dentry->d_inode)) {
+			/*
+			 * If we get here, it means that no copyup was
+			 * needed, and that a file by the old name already
+			 * existing on the destination branch; that file got
+			 * renamed earlier in this function, so all we need
+			 * to do here is set the lower inode.
+			 */
+			struct inode *inode;
+			inode = unionfs_lower_inode(old_dentry->d_inode);
+			igrab(inode);
+			unionfs_set_lower_inode_idx(new_dentry->d_inode,
+						    dbstart(new_dentry),
+						    inode);
+		}
+	}
+	/* if all of this renaming succeeded, update our times */
+	unionfs_copy_attr_times(old_dir);
+	unionfs_copy_attr_times(new_dir);
+	unionfs_copy_attr_times(old_dentry->d_inode);
+	unionfs_copy_attr_times(new_dentry->d_inode);
+	unionfs_check_inode(old_dir);
+	unionfs_check_inode(new_dir);
+	unionfs_check_dentry(old_dentry);
+	unionfs_check_dentry(new_dentry);
+
+out:
+	if (err)		/* clear the new_dentry stuff created */
+		d_drop(new_dentry);
+	unionfs_unlock_dentry(new_dentry);
+	unionfs_unlock_dentry(old_dentry);
+	unionfs_read_unlock(old_dentry->d_sb);
+	return err;
+}
-- 
1.5.2.2

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