Message-ID: <20060901015445.GO5788@fsl.cs.sunysb.edu>
Date:	Thu, 31 Aug 2006 21:54:45 -0400
From:	Josef Sipek <jsipek@...sunysb.edu>
To:	linux-kernel@...r.kernel.org
Cc:	linux-fsdevel@...r.kernel.org, hch@...radead.org, akpm@...l.org,
	viro@....linux.org.uk
Subject: [PATCH 14/22][RFC] Unionfs: Rename

From: Josef "Jeff" Sipek <jsipek@...sunysb.edu>

This patch provides rename functionality for Unionfs.

Signed-off-by: Josef "Jeff" Sipek <jsipek@...sunysb.edu>
Signed-off-by: David Quigley <dquigley@....cs.sunysb.edu>
Signed-off-by: Erez Zadok <ezk@...sunysb.edu>

---

 fs/unionfs/rename.c |  480 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 480 insertions(+)

diff -Nur -x linux-2.6-git/Documentation/dontdiff linux-2.6-git/fs/unionfs/rename.c linux-2.6-git-unionfs/fs/unionfs/rename.c
--- linux-2.6-git/fs/unionfs/rename.c	1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6-git-unionfs/fs/unionfs/rename.c	2006-08-31 19:04:00.000000000 -0400
@@ -0,0 +1,480 @@
+/*
+ * Copyright (c) 2003-2006 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2006 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) 2003-2006 Stony Brook University
+ * Copyright (c) 2003-2006 The Research Foundation of State University of New York
+ *
+ * For specific licensing information, see the COPYING file distributed with
+ * this package.
+ *
+ * This Copyright notice must be kept intact and distributed with all sources.
+ */
+
+#include "union.h"
+
+static int do_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 *hidden_old_dentry;
+	struct dentry *hidden_new_dentry;
+	struct dentry *hidden_old_dir_dentry;
+	struct dentry *hidden_new_dir_dentry;
+	struct dentry *hidden_wh_dentry;
+	struct dentry *hidden_wh_dir_dentry;
+	char *wh_name = NULL;
+
+	hidden_new_dentry = dtohd_index(new_dentry, bindex);
+	hidden_old_dentry = dtohd_index(old_dentry, bindex);
+
+	if (!hidden_new_dentry) {
+		hidden_new_dentry =
+		    create_parents(new_dentry->d_parent->d_inode, new_dentry, bindex);
+		if (IS_ERR(hidden_new_dentry)) {
+			printk(KERN_DEBUG "error creating directory tree for"
+					  " rename, bindex = %d, err = %ld\n",
+				          bindex, PTR_ERR(hidden_new_dentry));
+			err = PTR_ERR(hidden_new_dentry);
+			goto out;
+		}
+	}
+
+	wh_name = alloc_whname(new_dentry->d_name.name, new_dentry->d_name.len);
+	if (IS_ERR(wh_name)) {
+		err = PTR_ERR(wh_name);
+		goto out;
+	}
+
+	hidden_wh_dentry =
+	    lookup_one_len(wh_name, hidden_new_dentry->d_parent,
+			   new_dentry->d_name.len + UNIONFS_WHLEN);
+	if (IS_ERR(hidden_wh_dentry)) {
+		err = PTR_ERR(hidden_wh_dentry);
+		goto out;
+	}
+
+	if (hidden_wh_dentry->d_inode) {
+		/* get rid of the whiteout that is existing */
+		if (hidden_new_dentry->d_inode) {
+			printk(KERN_WARNING "Both a whiteout and a dentry"
+					" exist when doing a rename!\n");
+			err = -EIO;
+
+			dput(hidden_wh_dentry);
+			goto out;
+		}
+
+		hidden_wh_dir_dentry = lock_parent(hidden_wh_dentry);
+		if (!(err = is_robranch_super(old_dentry->d_sb, bindex))) {
+			err = vfs_unlink(hidden_wh_dir_dentry->d_inode,
+					       hidden_wh_dentry);
+		}
+		dput(hidden_wh_dentry);
+		unlock_dir(hidden_wh_dir_dentry);
+		if (err)
+			goto out;
+	} else
+		dput(hidden_wh_dentry);
+
+	dget(hidden_old_dentry);
+	hidden_old_dir_dentry = dget_parent(hidden_old_dentry);
+	hidden_new_dir_dentry = dget_parent(hidden_new_dentry);
+
+	lock_rename(hidden_old_dir_dentry, hidden_new_dir_dentry);
+
+	err = is_robranch_super(old_dentry->d_sb, bindex);
+	if (err)
+		goto out_unlock;
+
+	/* 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 (IS_ERR(whname))
+			goto out_unlock;
+		*wh_old = lookup_one_len(whname, hidden_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_unlock;
+		}
+	}
+
+	err = vfs_rename(hidden_old_dir_dentry->d_inode, hidden_old_dentry,
+			 hidden_new_dir_dentry->d_inode, hidden_new_dentry);
+
+out_unlock:
+	unlock_rename(hidden_old_dir_dentry, hidden_new_dir_dentry);
+
+	dput(hidden_old_dir_dentry);
+	dput(hidden_new_dir_dentry);
+	dput(hidden_old_dentry);
+
+out:
+	if (!err) {
+		/* Fixup the newdentry. */
+		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;
+}
+
+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 = do_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 = dtohd_index(new_dentry, bindex);
+		if (!unlink_dentry) {
+			continue;
+		}
+
+		unlink_dir_dentry = lock_parent(unlink_dentry);
+		if (!(err = is_robranch_super(old_dir->i_sb, bindex))) {
+			err =
+			    vfs_unlink(unlink_dir_dentry->d_inode,
+				       unlink_dentry);
+		}
+
+		fist_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 =
+		    get_nlinks(new_dentry->d_parent->d_inode);
+
+		unlock_dir(unlink_dir_dentry);
+		if (!err) {
+			if (bindex != new_bstart) {
+				dput(unlink_dentry);
+				set_dtohd_index(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, NULL,
+					  old_dentry->d_inode->i_size);
+			if (!err) {
+				dput(wh_old);
+				bwh_old = bindex;
+				err =
+				    do_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 *hidden_parent;
+		BUG_ON(!wh_old || IS_ERR(wh_old) || wh_old->d_inode
+		       || bwh_old < 0);
+		hidden_parent = lock_parent(wh_old);
+		local_err = vfs_create(hidden_parent->d_inode, wh_old, S_IRUGO,
+				       NULL);
+		unlock_dir(hidden_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("<0>We can't create a whiteout for the source in rename!\n");
+			err = -EIO;
+		}
+	}
+
+out:
+	dput(wh_old);
+	return err;
+
+revert:
+	/* Do revert here. */
+	local_err = unionfs_refresh_hidden_dentry(new_dentry, old_bstart);
+	if (local_err) {
+		printk(KERN_WARNING
+		       "Revert failed in rename: the new refresh failed.\n");
+		eio = -EIO;
+	}
+
+	local_err = unionfs_refresh_hidden_dentry(old_dentry, old_bstart);
+	if (local_err) {
+		printk(KERN_WARNING
+		       "Revert failed in rename: the old refresh failed.\n");
+		eio = -EIO;
+		goto revert_out;
+	}
+
+	if (!dtohd_index(new_dentry, bindex)
+	    || !dtohd_index(new_dentry, bindex)->d_inode) {
+		printk(KERN_WARNING
+		       "Revert failed in rename: the object disappeared from under us!\n");
+		eio = -EIO;
+		goto revert_out;
+	}
+
+	if (dtohd_index(old_dentry, bindex)
+	    && dtohd_index(old_dentry, bindex)->d_inode) {
+		printk(KERN_WARNING
+		       "Revert failed in rename: the object was created underneath us!\n");
+		eio = -EIO;
+		goto revert_out;
+	}
+
+	local_err =
+	    do_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_WARNING "Revert failed in rename!\n");
+		eio = -EIO;
+	}
+
+	local_err = unionfs_refresh_hidden_dentry(new_dentry, bindex);
+	if (local_err)
+		eio = -EIO;
+	local_err = unionfs_refresh_hidden_dentry(old_dentry, bindex);
+	if (local_err)
+		eio = -EIO;
+
+revert_out:
+	if (eio)
+		err = eio;
+	return err;
+}
+
+/*
+ * Unfortunately, we cannot simply call things like dbstart() in different
+ * places of the rename code because we move things around. So, we use this
+ * structure to pass the necessary information around to all the places that
+ * need it.
+ */
+struct rename_info {
+	int do_copyup;
+	int do_whiteout;
+	int rename_ok;
+
+	int old_bstart;
+	int old_bend;
+	int new_bstart;
+	int new_bend;
+
+	int isdir;		/* Is the source a directory? */
+	int clobber;		/* Are we clobbering the destination? */
+
+	int bwh_old;		/* where we create the whiteout */
+	struct dentry *wh_old;	/* lookup and set by do_rename() */
+};
+
+static struct dentry *lookup_whiteout(struct dentry *dentry)
+{
+	char *whname;
+	int bindex = -1, bstart = -1, bend = -1;
+	struct dentry *parent, *hidden_parent, *wh_dentry;
+
+	whname = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+	if (IS_ERR(whname))
+		return (void *)whname;
+
+	parent = dget_parent(dentry);
+	lock_dentry(parent);
+	bstart = dbstart(parent);
+	bend = dbend(parent);
+	wh_dentry = ERR_PTR(-ENOENT);
+	for (bindex = bstart; bindex <= bend; bindex++) {
+		hidden_parent = dtohd_index(parent, bindex);
+		if (!hidden_parent)
+			continue;
+		wh_dentry =
+		    lookup_one_len(whname, hidden_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);
+	}
+	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 let the userspace 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;
+
+	double_lock_dentry(old_dentry, new_dentry);
+
+	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 hidden because of whiteout,
+	 * simply override it even if the whiteouted 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;
+			/* 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);
+
+out:
+
+	if (err) {
+		/* clear the new_dentry stuff created */
+		d_drop(new_dentry);
+	} else {
+		/* force re-lookup since the dir on ro branch is not renamed,
+		   and hidden dentries still indicate the un-renamed ones. */
+		if (S_ISDIR(old_dentry->d_inode->i_mode))
+			atomic_dec(&dtopd(old_dentry)->udi_generation);
+	}
+
+	unlock_dentry(new_dentry);
+	unlock_dentry(old_dentry);
+	return err;
+}
+
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