[PATCH 10/22][RFC] Unionfs: Inode operations

Josef Sipek
2006-09-01T01:49:52Z

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

This patch provides the inode operations for Unionfs.

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

---

fs/unionfs/inode.c | 925 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 925 insertions(+)

diff -Nur -x linux-2.6-git/Documentation/dontdiff linux-2.6-git/fs/unionfs/inode.c linux-2.6-git-unionfs/fs/unionfs/inode.c
--- linux-2.6-git/fs/unionfs/inode.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-2.6-git-unionfs/fs/unionfs/inode.c 2006-08-31 19:04:00.000000000 -0400
@@ -0,0 +1,925 @@
+/*
+ * 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"
+
+/* declarations added for "sparse" */
+extern struct dentry *unionfs_lookup(struct inode *, struct dentry *,
+ struct nameidata *);
+extern int unionfs_readlink(struct dentry *dentry, char __user * buf,
+ int bufsiz);
+extern void unionfs_put_link(struct dentry *dentry, struct nameidata *nd,
+ void *cookie);
+
+static int unionfs_create(struct inode *parent, struct dentry *dentry,
+ int mode, struct nameidata *nd)
+{
+ int err = 0;
+ struct dentry *hidden_dentry = NULL;
+ struct dentry *whiteout_dentry = NULL;
+ struct dentry *new_hidden_dentry;
+ struct dentry *hidden_parent_dentry = NULL;
+ int bindex = 0, bstart;
+ char *name = NULL;
+
+ lock_dentry(dentry);
+
+ /* We start out in the leftmost branch. */
+ bstart = dbstart(dentry);
+ hidden_dentry = dtohd(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 (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry =
+ lookup_one_len(name, hidden_dentry->d_parent,
+ dentry->d_name.len + UNIONFS_WHLEN);
+ if (IS_ERR(whiteout_dentry)) {
+ err = PTR_ERR(whiteout_dentry);
+ whiteout_dentry = NULL;
+ goto out;
+ }
+
+ if (whiteout_dentry->d_inode) {
+ /* .wh.foo has been found. */
+ /* First truncate it and then rename it to foo (hence having
+ * the same overall effect as a normal create.
+ */
+ struct dentry *hidden_dir_dentry;
+ struct iattr newattrs;
+
+ mutex_lock(&whiteout_dentry->d_inode->i_mutex);
+ newattrs.ia_valid = ATTR_CTIME | ATTR_MODE | ATTR_ATIME
+ | ATTR_MTIME | ATTR_UID | ATTR_GID | ATTR_FORCE
+ | ATTR_KILL_SUID | ATTR_KILL_SGID;
+
+ newattrs.ia_mode = mode & ~current->fs->umask;
+ newattrs.ia_uid = current->fsuid;
+ newattrs.ia_gid = current->fsgid;
+
+ if (whiteout_dentry->d_inode->i_size != 0) {
+ newattrs.ia_valid |= ATTR_SIZE;
+ newattrs.ia_size = 0;
+ }
+
+ err = notify_change(whiteout_dentry, &newattrs);
+
+ mutex_unlock(&whiteout_dentry->d_inode->i_mutex);
+
+ if (err)
+ printk(KERN_WARNING
+ "unionfs: %s:%d: notify_change failed: %d, ignoring..\n",
+ __FILE__, __LINE__, err);
+
+ new_hidden_dentry = dtohd(dentry);
+ dget(new_hidden_dentry);
+
+ hidden_dir_dentry = dget_parent(whiteout_dentry);
+ lock_rename(hidden_dir_dentry, hidden_dir_dentry);
+
+ if (!(err = is_robranch_super(dentry->d_sb, bstart))) {
+ err =
+ vfs_rename(hidden_dir_dentry->d_inode,
+ whiteout_dentry,
+ hidden_dir_dentry->d_inode,
+ new_hidden_dentry);
+ }
+ if (!err) {
+ fist_copy_attr_timesizes(parent,
+ new_hidden_dentry->d_parent->
+ d_inode);
+ parent->i_nlink = get_nlinks(parent);
+ }
+
+ unlock_rename(hidden_dir_dentry, hidden_dir_dentry);
+ dput(hidden_dir_dentry);
+
+ dput(new_hidden_dentry);
+
+ if (err) {
+ /* exit if the error returned was NOT -EROFS */
+ if (!IS_COPYUP_ERR(err))
+ goto out;
+ /* We were not able to create the file in this branch,
+ * so, we try to create it in one branch to left
+ */
+ bstart--;
+ } else {
+ /* reset the unionfs dentry to point to the .wh.foo entry. */
+
+ /* Discard any old reference. */
+ dput(dtohd(dentry));
+
+ /* Trade one reference to another. */
+ set_dtohd_index(dentry, bstart, whiteout_dentry);
+ whiteout_dentry = NULL;
+
+ err = unionfs_interpose(dentry, parent->i_sb, 0);
+ goto out;
+ }
+ }
+
+ for (bindex = bstart; bindex >= 0; bindex--) {
+ hidden_dentry = dtohd_index(dentry, bindex);
+ if (!hidden_dentry) {
+ /* if hidden_dentry is NULL, create the entire
+ * dentry directory structure in branch 'bindex'.
+ * hidden_dentry will NOT be null when bindex == bstart
+ * because lookup passed as a negative unionfs dentry
+ * pointing to a lone negative underlying dentry */
+ hidden_dentry = create_parents(parent, dentry, bindex);
+ if (!hidden_dentry || IS_ERR(hidden_dentry)) {
+ if (IS_ERR(hidden_dentry))
+ err = PTR_ERR(hidden_dentry);
+ continue;
+ }
+ }
+
+ hidden_parent_dentry = lock_parent(hidden_dentry);
+ if (IS_ERR(hidden_parent_dentry)) {
+ err = PTR_ERR(hidden_parent_dentry);
+ goto out;
+ }
+ /* We shouldn't create things in a read-only branch. */
+ if (!(err = is_robranch_super(dentry->d_sb, bindex))) {
+ //DQ: vfs_create has a different prototype in 2.6
+ err = vfs_create(hidden_parent_dentry->d_inode,
+ hidden_dentry, mode, nd);
+ }
+ if (err || !hidden_dentry->d_inode) {
+ unlock_dir(hidden_parent_dentry);
+
+ /* break out of for loop if the error wasn't -EROFS */
+ if (!IS_COPYUP_ERR(err))
+ break;
+ } else {
+ err = unionfs_interpose(dentry, parent->i_sb, 0);
+ if (!err) {
+ fist_copy_attr_timesizes(parent,
+ hidden_parent_dentry->
+ d_inode);
+ /* update number of links on parent directory */
+ parent->i_nlink = get_nlinks(parent);
+ }
+ unlock_dir(hidden_parent_dentry);
+ break;
+ }
+ }
+
+out:
+ dput(whiteout_dentry);
+ kfree(name);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
+struct dentry *unionfs_lookup(struct inode *parent, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ /* The locking is done by unionfs_lookup_backend. */
+ return unionfs_lookup_backend(dentry, INTERPOSE_LOOKUP);
+}
+
+static int unionfs_link(struct dentry *old_dentry, struct inode *dir,
+ struct dentry *new_dentry)
+{
+ int err = 0;
+ struct dentry *hidden_old_dentry = NULL;
+ struct dentry *hidden_new_dentry = NULL;
+ struct dentry *hidden_dir_dentry = NULL;
+ struct dentry *whiteout_dentry;
+ char *name = NULL;
+
+ double_lock_dentry(new_dentry, old_dentry);
+
+ hidden_new_dentry = dtohd(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 (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry =
+ lookup_one_len(name, hidden_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() */
+ hidden_dir_dentry = lock_parent(whiteout_dentry);
+ if (!
+ (err =
+ is_robranch_super(new_dentry->d_sb,
+ dbstart(new_dentry)))) {
+ err =
+ vfs_unlink(hidden_dir_dentry->d_inode,
+ whiteout_dentry);
+ }
+ fist_copy_attr_times(dir, hidden_dir_dentry->d_inode);
+ dir->i_nlink = get_nlinks(dir);
+ unlock_dir(hidden_dir_dentry);
+ hidden_dir_dentry = NULL;
+ dput(whiteout_dentry);
+ if (err)
+ goto out;
+ }
+
+ if (dbstart(old_dentry) != dbstart(new_dentry)) {
+ hidden_new_dentry =
+ create_parents(dir, new_dentry, dbstart(old_dentry));
+ err = PTR_ERR(hidden_new_dentry);
+ if (IS_COPYUP_ERR(err))
+ goto docopyup;
+ if (!hidden_new_dentry || IS_ERR(hidden_new_dentry))
+ goto out;
+ }
+ hidden_new_dentry = dtohd(new_dentry);
+ hidden_old_dentry = dtohd(old_dentry);
+
+ BUG_ON(dbstart(old_dentry) != dbstart(new_dentry));
+ hidden_dir_dentry = lock_parent(hidden_new_dentry);
+ if (!(err = is_robranch(old_dentry)))
+ err =
+ vfs_link(hidden_old_dentry, hidden_dir_dentry->d_inode,
+ hidden_new_dentry);
+ unlock_dir(hidden_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, NULL,
+ old_dentry->d_inode->i_size);
+ if (!err) {
+ hidden_new_dentry =
+ create_parents(dir, new_dentry, bindex);
+ hidden_old_dentry = dtohd(old_dentry);
+ hidden_dir_dentry =
+ lock_parent(hidden_new_dentry);
+ /* do vfs_link */
+ err =
+ vfs_link(hidden_old_dentry,
+ hidden_dir_dentry->d_inode,
+ hidden_new_dentry);
+ unlock_dir(hidden_dir_dentry);
+ goto check_link;
+ }
+ }
+ goto out;
+ }
+check_link:
+ if (err || !hidden_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);
+ fist_copy_attr_all(dir, hidden_new_dentry->d_parent->d_inode);
+ /* propagate number of hard-links */
+ old_dentry->d_inode->i_nlink = get_nlinks(old_dentry->d_inode);
+
+out:
+ if (!new_dentry->d_inode)
+ d_drop(new_dentry);
+
+ kfree(name);
+
+ unlock_dentry(new_dentry);
+ unlock_dentry(old_dentry);
+
+ return err;
+}
+
+static int unionfs_symlink(struct inode *dir, struct dentry *dentry,
+ const char *symname)
+{
+ int err = 0;
+ struct dentry *hidden_dentry = NULL;
+ struct dentry *whiteout_dentry = NULL;
+ struct dentry *hidden_dir_dentry = NULL;
+ umode_t mode;
+ int bindex = 0, bstart;
+ char *name = NULL;
+
+ lock_dentry(dentry);
+
+ /* We start out in the leftmost branch. */
+ bstart = dbstart(dentry);
+
+ hidden_dentry = dtohd(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 (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry =
+ lookup_one_len(name, hidden_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() */
+ hidden_dir_dentry = lock_parent(whiteout_dentry);
+
+ if (!(err = is_robranch_super(dentry->d_sb, bstart))) {
+ err =
+ vfs_unlink(hidden_dir_dentry->d_inode,
+ whiteout_dentry);
+ }
+ dput(whiteout_dentry);
+
+ fist_copy_attr_times(dir, hidden_dir_dentry->d_inode);
+ /* propagate number of hard-links */
+ dir->i_nlink = get_nlinks(dir);
+
+ unlock_dir(hidden_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--) {
+ hidden_dentry = dtohd_index(dentry, bindex);
+ if (!hidden_dentry) {
+ /* if hidden_dentry is NULL, create the entire
+ * dentry directory structure in branch 'bindex'. hidden_dentry will NOT be null when
+ * bindex == bstart because lookup passed as a negative unionfs dentry pointing to a
+ * lone negative underlying dentry */
+ hidden_dentry = create_parents(dir, dentry, bindex);
+ if (!hidden_dentry || IS_ERR(hidden_dentry)) {
+ if (IS_ERR(hidden_dentry)) {
+ err = PTR_ERR(hidden_dentry);
+ }
+ printk(KERN_DEBUG
+ "hidden dentry NULL (or error) for bindex = %d\n",
+ bindex);
+ continue;
+ }
+ }
+
+ hidden_dir_dentry = lock_parent(hidden_dentry);
+
+ if (!(err = is_robranch_super(dentry->d_sb, bindex))) {
+ mode = S_IALLUGO;
+ err =
+ vfs_symlink(hidden_dir_dentry->d_inode,
+ hidden_dentry, symname, mode);
+ }
+ unlock_dir(hidden_dir_dentry);
+
+ if (err || !hidden_dentry->d_inode) {
+ /* break out of for loop if error returned was NOT -EROFS */
+ if (!IS_COPYUP_ERR(err))
+ break;
+ } else {
+ err = unionfs_interpose(dentry, dir->i_sb, 0);
+ if (!err) {
+ fist_copy_attr_timesizes(dir,
+ hidden_dir_dentry->
+ d_inode);
+ /* update number of links on parent directory */
+ dir->i_nlink = get_nlinks(dir);
+ }
+ break;
+ }
+ }
+
+out:
+ if (!dentry->d_inode)
+ d_drop(dentry);
+
+ kfree(name);
+ unlock_dentry(dentry);
+ return err;
+}
+
+static int unionfs_mkdir(struct inode *parent, struct dentry *dentry, int mode)
+{
+ int err = 0;
+ struct dentry *hidden_dentry = NULL, *whiteout_dentry = NULL;
+ struct dentry *hidden_parent_dentry = NULL;
+ int bindex = 0, bstart;
+ char *name = NULL;
+ int whiteout_unlinked = 0;
+ struct sioq_args args;
+
+ lock_dentry(dentry);
+ bstart = dbstart(dentry);
+
+ hidden_dentry = dtohd(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 (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry = lookup_one_len(name, hidden_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 {
+ hidden_parent_dentry = lock_parent(whiteout_dentry);
+
+ //found a.wh.foo entry, remove it then do vfs_mkdir
+ if (!(err = is_robranch_super(dentry->d_sb, bstart))) {
+ args.u.unlink.parent = hidden_parent_dentry->d_inode;
+ args.u.unlink.dentry = whiteout_dentry;
+ run_sioq(__unionfs_unlink, &args);
+ err = args.err;
+ }
+ dput(whiteout_dentry);
+
+ unlock_dir(hidden_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;
+
+ hidden_dentry = dtohd_index(dentry, bindex);
+ if (!hidden_dentry) {
+ hidden_dentry = create_parents(parent, dentry, bindex);
+ if (!hidden_dentry || IS_ERR(hidden_dentry)) {
+ printk(KERN_DEBUG
+ "hidden dentry NULL for bindex = %d\n",
+ bindex);
+ continue;
+ }
+ }
+
+ hidden_parent_dentry = lock_parent(hidden_dentry);
+
+ if (IS_ERR(hidden_parent_dentry)) {
+ err = PTR_ERR(hidden_parent_dentry);
+ goto out;
+ }
+
+ err = vfs_mkdir(hidden_parent_dentry->d_inode, hidden_dentry, mode);
+
+ unlock_dir(hidden_parent_dentry);
+
+ /* did the mkdir suceed? */
+ if (err)
+ break;
+
+ for (i = bindex + 1; i < bend; i++) {
+ if (dtohd_index(dentry, i)) {
+ dput(dtohd_index(dentry, i));
+ set_dtohd_index(dentry, i, NULL);
+ }
+ }
+ set_dbend(dentry, bindex);
+
+ err = unionfs_interpose(dentry, parent->i_sb, 0);
+ if (!err) {
+ fist_copy_attr_timesizes(parent,
+ hidden_parent_dentry->d_inode);
+
+ /* update number of links on parent directory */
+ parent->i_nlink = get_nlinks(parent);
+ }
+
+ err = make_dir_opaque(dentry, dbstart(dentry));
+ if (err) {
+ printk(KERN_DEBUG "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);
+
+ unlock_dentry(dentry);
+ return err;
+}
+
+static int unionfs_mknod(struct inode *dir, struct dentry *dentry, int mode,
+ dev_t dev)
+{
+ int err = 0;
+ struct dentry *hidden_dentry = NULL, *whiteout_dentry = NULL;
+ struct dentry *hidden_parent_dentry = NULL;
+ int bindex = 0, bstart;
+ char *name = NULL;
+ int whiteout_unlinked = 0;
+
+ lock_dentry(dentry);
+ bstart = dbstart(dentry);
+
+ hidden_dentry = dtohd(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 (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ whiteout_dentry =
+ lookup_one_len(name, hidden_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 */
+ hidden_parent_dentry = lock_parent(whiteout_dentry);
+
+ //found a.wh.foo entry, remove it then do vfs_mkdir
+ if (!(err = is_robranch_super(dentry->d_sb, bstart)))
+ err = vfs_unlink(hidden_parent_dentry->d_inode,
+ whiteout_dentry);
+ dput(whiteout_dentry);
+
+ unlock_dir(hidden_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;
+
+ hidden_dentry = dtohd_index(dentry, bindex);
+ if (!hidden_dentry) {
+ hidden_dentry = create_parents(dir, dentry, bindex);
+ if (IS_ERR(hidden_dentry)) {
+ printk(KERN_DEBUG
+ "failed to create parents on %d, err = %ld\n",
+ bindex, PTR_ERR(hidden_dentry));
+ continue;
+ }
+ }
+
+ hidden_parent_dentry = lock_parent(hidden_dentry);
+ if (IS_ERR(hidden_parent_dentry)) {
+ err = PTR_ERR(hidden_parent_dentry);
+ goto out;
+ }
+
+ err = vfs_mknod(hidden_parent_dentry->d_inode,
+ hidden_dentry, mode, dev);
+
+ if (err) {
+ unlock_dir(hidden_parent_dentry);
+ break;
+ }
+
+ err = unionfs_interpose(dentry, dir->i_sb, 0);
+ if (!err) {
+ fist_copy_attr_timesizes(dir,
+ hidden_parent_dentry->
+ d_inode);
+ /* update number of links on parent directory */
+ dir->i_nlink = get_nlinks(dir);
+ }
+ unlock_dir(hidden_parent_dentry);
+
+ break;
+ }
+
+out:
+ if (!dentry->d_inode)
+ d_drop(dentry);
+
+ if (name) {
+ kfree(name);
+ }
+
+ unlock_dentry(dentry);
+ return err;
+}
+
+int unionfs_readlink(struct dentry *dentry, char __user * buf, int bufsiz)
+{
+ int err;
+ struct dentry *hidden_dentry;
+
+ lock_dentry(dentry);
+ hidden_dentry = dtohd(dentry);
+
+ if (!hidden_dentry->d_inode->i_op ||
+ !hidden_dentry->d_inode->i_op->readlink) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = hidden_dentry->d_inode->i_op->readlink(hidden_dentry,
+ buf, bufsiz);
+ if (err > 0)
+ fist_copy_attr_atime(dentry->d_inode, hidden_dentry->d_inode);
+
+out:
+ unlock_dentry(dentry);
+ return err;
+}
+
+/* We don't lock the dentry here, because readlink does the heavy lifting. */
+static void *unionfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ char *buf;
+ int len = PAGE_SIZE, err;
+ mm_segment_t old_fs;
+
+ /* This is freed by the put_link method assuming a successful call. */
+ buf = (char *)kmalloc(len, GFP_KERNEL);
+ if (!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:
+ return ERR_PTR(err);
+}
+
+void unionfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
+{
+ char *link;
+ link = nd_get_link(nd);
+ kfree(link);
+}
+
+/* Basically copied from the kernel vfs permission(), but we've changed
+ * the following: (1) the IS_RDONLY check is skipped, and (2) if you set
+ * the mount option `nfsperms=insceure', we assume that -EACCES means that
+ * the export is read-only and we should check standard Unix permissions.
+ * This means that NFS ACL checks (or other advanced permission features)
+ * are bypassed.
+ */
+static int inode_permission(struct inode *inode, int mask, struct nameidata *nd,
+ int bindex)
+{
+ int retval, submask;
+
+ if (mask & MAY_WRITE) {
+ /* The first branch is allowed to be really readonly. */
+ if (bindex == 0) {
+ umode_t mode = inode->i_mode;
+ if (IS_RDONLY(inode) && (S_ISREG(mode) || S_ISDIR(mode)
+ || S_ISLNK(mode)))
+ return -EROFS;
+ }
+ /*
+ * Nobody gets write access to an immutable file.
+ */
+ if (IS_IMMUTABLE(inode))
+ return -EACCES;
+ }
+
+ /* Ordinary permission routines do not understand MAY_APPEND. */
+ submask = mask & ~MAY_APPEND;
+ if (inode->i_op && inode->i_op->permission) {
+ retval = inode->i_op->permission(inode, submask, nd);
+ if ((retval == -EACCES) && (submask & MAY_WRITE) &&
+ (!strcmp("nfs", (inode)->i_sb->s_type->name)) &&
+ (nd) && (nd->mnt) && (nd->mnt->mnt_sb) &&
+ (branchperms(nd->mnt->mnt_sb, bindex) & MAY_NFSRO)) {
+ retval = generic_permission(inode, submask, NULL);
+ }
+ } else {
+ retval = generic_permission(inode, submask, NULL);
+ }
+
+ if (retval && retval != -EROFS) /* ignore EROFS */
+ return retval;
+
+ retval = security_inode_permission(inode, mask, nd);
+ return ((retval == -EROFS) ? 0 : retval); /* ignore EROFS */
+}
+
+static int unionfs_permission(struct inode *inode, int mask,
+ struct nameidata *nd)
+{
+ struct inode *hidden_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);
+
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_inode = itohi_index(inode, bindex);
+ if (!hidden_inode)
+ continue;
+
+ /* check the condition for D-F-D underlying files/directories,
+ * we dont have to check for files, if we are checking for
+ * directories.
+ */
+ if (!is_file && !S_ISDIR(hidden_inode->i_mode))
+ continue;
+ /* We use our own special version of permission, such that
+ * only the first branch returns -EROFS. */
+ err = inode_permission(hidden_inode, mask, nd, bindex);
+ /* 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(hidden_inode);
+ if (!err)
+ put_write_access(hidden_inode);
+ }
+ break;
+ }
+ }
+
+out:
+ return err;
+}
+
+static int unionfs_setattr(struct dentry *dentry, struct iattr *ia)
+{
+ int err = 0;
+ struct dentry *hidden_dentry;
+ struct inode *inode = NULL;
+ struct inode *hidden_inode = NULL;
+ int bstart, bend, bindex;
+ int i;
+ int copyup = 0;
+
+ lock_dentry(dentry);
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+ inode = dentry->d_inode;
+
+ for (bindex = bstart; (bindex <= bend) || (bindex == bstart); bindex++) {
+ hidden_dentry = dtohd_index(dentry, bindex);
+ if (!hidden_dentry)
+ continue;
+ BUG_ON(hidden_dentry->d_inode == NULL);
+
+ /* If the file is on a read only branch */
+ if (is_robranch_super(dentry->d_sb, bindex)
+ || IS_RDONLY(hidden_dentry->d_inode)) {
+ if (copyup || (bindex != bstart))
+ continue;
+ /* Only if its the leftmost file, copyup the file */
+ for (i = bstart - 1; i >= 0; i--) {
+ size_t size = dentry->d_inode->i_size;
+ if (ia->ia_valid & ATTR_SIZE)
+ size = ia->ia_size;
+ err = copyup_dentry(dentry->d_parent->d_inode,
+ dentry, bstart, i, NULL,
+ size);
+
+ if (!err) {
+ copyup = 1;
+ hidden_dentry = dtohd(dentry);
+ break;
+ }
+ /* if error is in the leftmost f/s, pass it up */
+ if (i == 0)
+ goto out;
+ }
+
+ }
+ err = notify_change(hidden_dentry, ia);
+ if (err)
+ goto out;
+ break;
+ }
+
+ /* get the size from the first hidden inode */
+ hidden_inode = itohi(dentry->d_inode);
+ fist_copy_attr_all(inode, hidden_inode);
+
+out:
+ unlock_dentry(dentry);
+ 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,
+};
+
+struct inode_operations unionfs_main_iops = {
+ .permission = unionfs_permission,
+ .setattr = unionfs_setattr,
+};
+