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Subject[PATCH 06/24] Unionfs: Dentry operations
Date
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

This patch contains the dentry 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/dentry.c | 243 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 243 insertions(+), 0 deletions(-)
diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
new file mode 100644
index 0000000..740c000
--- /dev/null
+++ b/fs/unionfs/dentry.c
@@ -0,0 +1,243 @@
+/*
+ * 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
+ *
+ * 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"
+
+/* declarations added for "sparse" */
+extern int unionfs_d_revalidate_wrap(struct dentry *dentry,
+ struct nameidata *nd);
+extern void unionfs_d_release(struct dentry *dentry);
+extern void unionfs_d_iput(struct dentry *dentry, struct inode *inode);
+
+/*
+ * returns 1 if valid, 0 otherwise.
+ */
+int unionfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+ int valid = 1; /* default is valid (1); invalid is 0. */
+ struct dentry *hidden_dentry;
+ int bindex, bstart, bend;
+ int sbgen, dgen;
+ int positive = 0;
+ int locked = 0;
+ int restart = 0;
+ int interpose_flag;
+
+ struct nameidata lowernd; /* TODO: be gentler to the stack */
+
+ if (nd)
+ memcpy(&lowernd, nd, sizeof(struct nameidata));
+ else
+ memset(&lowernd, 0, sizeof(struct nameidata));
+
+restart:
+ verify_locked(dentry);
+
+ /* if the dentry is unhashed, do NOT revalidate */
+ if (d_deleted(dentry)) {
+ printk(KERN_DEBUG "unhashed dentry being revalidated: %*s\n",
+ dentry->d_name.len, dentry->d_name.name);
+ goto out;
+ }
+
+ BUG_ON(dbstart(dentry) == -1);
+ if (dentry->d_inode)
+ positive = 1;
+ dgen = atomic_read(&UNIONFS_D(dentry)->generation);
+ sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
+ /* If we are working on an unconnected dentry, then there is no
+ * revalidation to be done, because this file does not exist within the
+ * namespace, and Unionfs operates on the namespace, not data.
+ */
+ if (sbgen != dgen) {
+ struct dentry *result;
+ int pdgen;
+
+ unionfs_read_lock(dentry->d_sb);
+ locked = 1;
+
+ /* The root entry should always be valid */
+ BUG_ON(IS_ROOT(dentry));
+
+ /* We can't work correctly if our parent isn't valid. */
+ pdgen = atomic_read(&UNIONFS_D(dentry->d_parent)->generation);
+ if (!restart && (pdgen != sbgen)) {
+ unionfs_read_unlock(dentry->d_sb);
+ locked = 0;
+ /* We must be locked before our parent. */
+ if (!
+ (dentry->d_parent->d_op->
+ d_revalidate(dentry->d_parent, nd))) {
+ valid = 0;
+ goto out;
+ }
+ restart = 1;
+ goto restart;
+ }
+ BUG_ON(pdgen != sbgen);
+
+ /* Free the pointers for our inodes and this dentry. */
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+ if (bstart >= 0) {
+ struct dentry *hidden_dentry;
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_dentry =
+ unionfs_lower_dentry_idx(dentry, bindex);
+ dput(hidden_dentry);
+ }
+ }
+ set_dbstart(dentry, -1);
+ set_dbend(dentry, -1);
+
+ interpose_flag = INTERPOSE_REVAL_NEG;
+ if (positive) {
+ interpose_flag = INTERPOSE_REVAL;
+ mutex_lock(&dentry->d_inode->i_mutex);
+ bstart = ibstart(dentry->d_inode);
+ bend = ibend(dentry->d_inode);
+ if (bstart >= 0) {
+ struct inode *hidden_inode;
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_inode =
+ unionfs_lower_inode_idx(dentry->d_inode,
+ bindex);
+ iput(hidden_inode);
+ }
+ }
+ kfree(UNIONFS_I(dentry->d_inode)->lower_inodes);
+ UNIONFS_I(dentry->d_inode)->lower_inodes = NULL;
+ ibstart(dentry->d_inode) = -1;
+ ibend(dentry->d_inode) = -1;
+ mutex_unlock(&dentry->d_inode->i_mutex);
+ }
+
+ result = unionfs_lookup_backend(dentry, &lowernd, interpose_flag);
+ if (result) {
+ if (IS_ERR(result)) {
+ valid = 0;
+ goto out;
+ }
+ /* current unionfs_lookup_backend() doesn't return
+ * a valid dentry
+ */
+ dput(dentry);
+ dentry = result;
+ }
+
+ if (positive && UNIONFS_I(dentry->d_inode)->stale) {
+ make_stale_inode(dentry->d_inode);
+ d_drop(dentry);
+ valid = 0;
+ goto out;
+ }
+ goto out;
+ }
+
+ /* The revalidation must occur across all branches */
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+ BUG_ON(bstart == -1);
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!hidden_dentry || !hidden_dentry->d_op
+ || !hidden_dentry->d_op->d_revalidate)
+ continue;
+
+ if (!hidden_dentry->d_op->d_revalidate(hidden_dentry, nd))
+ valid = 0;
+ }
+
+ if (!dentry->d_inode)
+ valid = 0;
+
+ if (valid) {
+ fsstack_copy_attr_all(dentry->d_inode,
+ unionfs_lower_inode(dentry->d_inode),
+ unionfs_get_nlinks);
+ fsstack_copy_inode_size(dentry->d_inode,
+ unionfs_lower_inode(dentry->d_inode));
+ }
+
+out:
+ if (locked)
+ unionfs_read_unlock(dentry->d_sb);
+ return valid;
+}
+
+int unionfs_d_revalidate_wrap(struct dentry *dentry, struct nameidata *nd)
+{
+ int err;
+
+ lock_dentry(dentry);
+ err = unionfs_d_revalidate(dentry, nd);
+ unlock_dentry(dentry);
+
+ return err;
+}
+
+void unionfs_d_release(struct dentry *dentry)
+{
+ int bindex, bstart, bend;
+
+ /* There is no reason to lock the dentry, because we have the only
+ * reference, but the printing functions verify that we have a lock
+ * on the dentry before calling dbstart, etc.
+ */
+ lock_dentry(dentry);
+
+ /* this could be a negative dentry, so check first */
+ if (!UNIONFS_D(dentry)) {
+ printk(KERN_DEBUG "dentry without private data: %.*s",
+ dentry->d_name.len, dentry->d_name.name);
+ goto out;
+ } else if (dbstart(dentry) < 0) {
+ /* this is due to a failed lookup */
+ printk(KERN_DEBUG "dentry without hidden dentries : %.*s",
+ dentry->d_name.len, dentry->d_name.name);
+ goto out_free;
+ }
+
+ /* Release all the hidden dentries */
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ dput(unionfs_lower_dentry_idx(dentry, bindex));
+ mntput(unionfs_lower_mnt_idx(dentry, bindex));
+
+ unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
+ unionfs_set_lower_mnt_idx(dentry, bindex, NULL);
+ }
+ /* free private data (unionfs_dentry_info) here */
+ kfree(UNIONFS_D(dentry)->lower_paths);
+ UNIONFS_D(dentry)->lower_paths = NULL;
+
+out_free:
+ /* No need to unlock it, because it is disappeared. */
+ free_dentry_private_data(UNIONFS_D(dentry));
+ dentry->d_fsdata = NULL; /* just to be safe */
+
+out:
+ return;
+}
+
+struct dentry_operations unionfs_dops = {
+ .d_revalidate = unionfs_d_revalidate_wrap,
+ .d_release = unionfs_d_release,
+};
+
--
1.4.4.2
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