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Subject[PATCH 23/35] Unionfs: Main module functions
Date
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

Module init & cleanup code, as well as interposition functions.

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/main.c | 685 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 685 insertions(+), 0 deletions(-)

diff --git a/fs/unionfs/main.c b/fs/unionfs/main.c
new file mode 100644
index 0000000..34fb5f8
--- /dev/null
+++ b/fs/unionfs/main.c
@@ -0,0 +1,685 @@
+/*
+ * 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"
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+/* sb we pass is unionfs's super_block */
+int unionfs_interpose(struct dentry *dentry, struct super_block *sb, int flag)
+{
+ struct inode *hidden_inode;
+ struct dentry *hidden_dentry;
+ int err = 0;
+ struct inode *inode;
+ int is_negative_dentry = 1;
+ int bindex, bstart, bend;
+
+ verify_locked(dentry);
+
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+
+ /* Make sure that we didn't get a negative dentry. */
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ if (unionfs_lower_dentry_idx(dentry, bindex) &&
+ unionfs_lower_dentry_idx(dentry, bindex)->d_inode) {
+ is_negative_dentry = 0;
+ break;
+ }
+ }
+ BUG_ON(is_negative_dentry);
+
+ /* We allocate our new inode below, by calling iget.
+ * iget will call our read_inode which will initialize some
+ * of the new inode's fields
+ */
+
+ /* On revalidate we've already got our own inode and just need
+ * to fix it up. */
+ if (flag == INTERPOSE_REVAL) {
+ inode = dentry->d_inode;
+ UNIONFS_I(inode)->bstart = -1;
+ UNIONFS_I(inode)->bend = -1;
+ atomic_set(&UNIONFS_I(inode)->generation,
+ atomic_read(&UNIONFS_SB(sb)->generation));
+
+ UNIONFS_I(inode)->lower_inodes =
+ kcalloc(sbmax(sb), sizeof(struct inode *), GFP_KERNEL);
+ if (!UNIONFS_I(inode)->lower_inodes) {
+ err = -ENOMEM;
+ goto out;
+ }
+ mutex_lock(&inode->i_mutex);
+ } else {
+ ino_t ino;
+ /* get unique inode number for unionfs */
+ ino = iunique(sb, UNIONFS_ROOT_INO);
+
+ inode = iget(sb, ino);
+ if (!inode) {
+ err = -EACCES; /* should be impossible??? */
+ goto out;
+ }
+
+ mutex_lock(&inode->i_mutex);
+ if (atomic_read(&inode->i_count) > 1)
+ goto skip;
+ }
+
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!hidden_dentry) {
+ unionfs_set_lower_inode_idx(inode, bindex, NULL);
+ continue;
+ }
+
+ /* Initialize the hidden inode to the new hidden inode. */
+ if (!hidden_dentry->d_inode)
+ continue;
+
+ unionfs_set_lower_inode_idx(inode, bindex,
+ igrab(hidden_dentry->d_inode));
+ }
+
+ ibstart(inode) = dbstart(dentry);
+ ibend(inode) = dbend(dentry);
+
+ /* Use attributes from the first branch. */
+ hidden_inode = unionfs_lower_inode(inode);
+
+ /* Use different set of inode ops for symlinks & directories */
+ if (S_ISLNK(hidden_inode->i_mode))
+ inode->i_op = &unionfs_symlink_iops;
+ else if (S_ISDIR(hidden_inode->i_mode))
+ inode->i_op = &unionfs_dir_iops;
+
+ /* Use different set of file ops for directories */
+ if (S_ISDIR(hidden_inode->i_mode))
+ inode->i_fop = &unionfs_dir_fops;
+
+ /* properly initialize special inodes */
+ if (S_ISBLK(hidden_inode->i_mode) || S_ISCHR(hidden_inode->i_mode) ||
+ S_ISFIFO(hidden_inode->i_mode) || S_ISSOCK(hidden_inode->i_mode))
+ init_special_inode(inode, hidden_inode->i_mode,
+ hidden_inode->i_rdev);
+ /* Fix our inode's address operations to that of the lower inode (Unionfs is FiST-Lite) */
+ if (inode->i_mapping->a_ops != hidden_inode->i_mapping->a_ops)
+ inode->i_mapping->a_ops = hidden_inode->i_mapping->a_ops;
+
+ /* all well, copy inode attributes */
+ fsstack_copy_attr_all(inode, hidden_inode, unionfs_get_nlinks);
+
+skip:
+ /* only (our) lookup wants to do a d_add */
+ switch (flag) {
+ case INTERPOSE_DEFAULT:
+ case INTERPOSE_REVAL_NEG:
+ d_instantiate(dentry, inode);
+ break;
+ case INTERPOSE_LOOKUP:
+ err = PTR_ERR(d_splice_alias(inode, dentry));
+ break;
+ case INTERPOSE_REVAL:
+ /* Do nothing. */
+ break;
+ default:
+ printk(KERN_ERR "Invalid interpose flag passed!");
+ BUG();
+ }
+
+ mutex_unlock(&inode->i_mutex);
+
+out:
+ return err;
+}
+
+void unionfs_reinterpose(struct dentry *dentry)
+{
+ struct dentry *hidden_dentry;
+ struct inode *inode;
+ int bindex, bstart, bend;
+
+ verify_locked(dentry);
+
+ /* This is pre-allocated inode */
+ inode = dentry->d_inode;
+
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ hidden_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (!hidden_dentry)
+ continue;
+
+ if (!hidden_dentry->d_inode)
+ continue;
+ if (unionfs_lower_inode_idx(inode, bindex))
+ continue;
+ unionfs_set_lower_inode_idx(inode, bindex, igrab(hidden_dentry->d_inode));
+ }
+ ibstart(inode) = dbstart(dentry);
+ ibend(inode) = dbend(dentry);
+}
+
+/* make sure the branch we just looked up (nd) makes sense:
+ *
+ * 1) we're not trying to stack unionfs on top of unionfs
+ * 2) it exists
+ * 3) is a directory
+ */
+int check_branch(struct nameidata *nd)
+{
+ if (!strcmp(nd->dentry->d_sb->s_type->name, "unionfs"))
+ return -EINVAL;
+ if (!nd->dentry->d_inode)
+ return -ENOENT;
+ if (!S_ISDIR(nd->dentry->d_inode->i_mode))
+ return -ENOTDIR;
+ return 0;
+}
+
+/* checks if two hidden_dentries have overlapping branches */
+int is_branch_overlap(struct dentry *dent1, struct dentry *dent2)
+{
+ struct dentry *dent = NULL;
+
+ dent = dent1;
+ while ((dent != dent2) && (dent->d_parent != dent))
+ dent = dent->d_parent;
+
+ if (dent == dent2)
+ return 1;
+
+ dent = dent2;
+ while ((dent != dent1) && (dent->d_parent != dent))
+ dent = dent->d_parent;
+
+ return (dent == dent1);
+}
+
+/* parse branch mode */
+static int parse_branch_mode(char *name)
+{
+ int perms;
+ int l = strlen(name);
+ if (!strcmp(name + l - 3, "=ro")) {
+ perms = MAY_READ;
+ name[l - 3] = '\0';
+ } else if (!strcmp(name + l - 3, "=rw")) {
+ perms = MAY_READ | MAY_WRITE;
+ name[l - 3] = '\0';
+ } else
+ perms = MAY_READ | MAY_WRITE;
+
+ return perms;
+}
+
+/* parse the dirs= mount argument */
+static int parse_dirs_option(struct super_block *sb, struct unionfs_dentry_info
+ *hidden_root_info, char *options)
+{
+ struct nameidata nd;
+ char *name;
+ int err = 0;
+ int branches = 1;
+ int bindex = 0;
+ int i = 0;
+ int j = 0;
+
+ struct dentry *dent1;
+ struct dentry *dent2;
+
+ if (options[0] == '\0') {
+ printk(KERN_WARNING "unionfs: no branches specified\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ /* Each colon means we have a separator, this is really just a rough
+ * guess, since strsep will handle empty fields for us. */
+ for (i = 0; options[i]; i++)
+ if (options[i] == ':')
+ branches++;
+
+ /* allocate space for underlying pointers to hidden dentry */
+ UNIONFS_SB(sb)->data = kcalloc(branches,
+ sizeof(struct unionfs_data), GFP_KERNEL);
+ if (!UNIONFS_SB(sb)->data) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ hidden_root_info->lower_paths = kcalloc(branches,
+ sizeof(struct path), GFP_KERNEL);
+ if (!hidden_root_info->lower_paths) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ /* now parsing the string b1:b2=rw:b3=ro:b4 */
+ branches = 0;
+ while ((name = strsep(&options, ":")) != NULL) {
+ int perms;
+
+ if (!*name)
+ continue;
+
+ branches++;
+
+ /* strip off =rw or =ro if it is specified. */
+ perms = parse_branch_mode(name);
+ if (!bindex && !(perms & MAY_WRITE)) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = path_lookup(name, LOOKUP_FOLLOW, &nd);
+ if (err) {
+ printk(KERN_WARNING "unionfs: error accessing "
+ "hidden directory '%s' (error %d)\n", name, err);
+ goto out;
+ }
+
+ if ((err = check_branch(&nd))) {
+ printk(KERN_WARNING "unionfs: hidden directory "
+ "'%s' is not a valid branch\n", name);
+ path_release(&nd);
+ goto out;
+ }
+
+ hidden_root_info->lower_paths[bindex].dentry = nd.dentry;
+ hidden_root_info->lower_paths[bindex].mnt = nd.mnt;
+
+ set_branchperms(sb, bindex, perms);
+ set_branch_count(sb, bindex, 0);
+
+ if (hidden_root_info->bstart < 0)
+ hidden_root_info->bstart = bindex;
+ hidden_root_info->bend = bindex;
+ bindex++;
+ }
+
+ if (branches == 0) {
+ printk(KERN_WARNING "unionfs: no branches specified\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ BUG_ON(branches != (hidden_root_info->bend + 1));
+
+ /* ensure that no overlaps exist in the branches */
+ for (i = 0; i < branches; i++) {
+ for (j = i + 1; j < branches; j++) {
+ dent1 = hidden_root_info->lower_paths[i].dentry;
+ dent2 = hidden_root_info->lower_paths[j].dentry;
+
+ if (is_branch_overlap(dent1, dent2)) {
+ printk(KERN_WARNING "unionfs: branches %d and "
+ "%d overlap\n", i, j);
+ err = -EINVAL;
+ goto out;
+ }
+ }
+ }
+
+out:
+ if (err) {
+ for (i = 0; i < branches; i++)
+ if (hidden_root_info->lower_paths[i].dentry) {
+ dput(hidden_root_info->lower_paths[i].dentry);
+ mntput(hidden_root_info->lower_paths[i].mnt);
+ }
+
+ kfree(hidden_root_info->lower_paths);
+ kfree(UNIONFS_SB(sb)->data);
+
+ /* MUST clear the pointers to prevent potential double free if
+ * the caller dies later on
+ */
+ hidden_root_info->lower_paths = NULL;
+ UNIONFS_SB(sb)->data = NULL;
+ }
+ return err;
+}
+
+/*
+ * Parse mount options. See the manual page for usage instructions.
+ *
+ * Returns the dentry object of the lower-level (hidden) directory;
+ * We want to mount our stackable file system on top of that hidden directory.
+ */
+static struct unionfs_dentry_info *unionfs_parse_options(struct super_block *sb,
+ char *options)
+{
+ struct unionfs_dentry_info *hidden_root_info;
+ char *optname;
+ int err = 0;
+ int bindex;
+ int dirsfound = 0;
+
+ /* allocate private data area */
+ err = -ENOMEM;
+ hidden_root_info =
+ kzalloc(sizeof(struct unionfs_dentry_info), GFP_KERNEL);
+ if (!hidden_root_info)
+ goto out_error;
+ hidden_root_info->bstart = -1;
+ hidden_root_info->bend = -1;
+ hidden_root_info->bopaque = -1;
+
+ while ((optname = strsep(&options, ",")) != NULL) {
+ char *optarg;
+ char *endptr;
+ int intval;
+
+ if (!*optname)
+ continue;
+
+ optarg = strchr(optname, '=');
+ if (optarg)
+ *optarg++ = '\0';
+
+ /* All of our options take an argument now. Insert ones that
+ * don't, above this check. */
+ if (!optarg) {
+ printk("unionfs: %s requires an argument.\n", optname);
+ err = -EINVAL;
+ goto out_error;
+ }
+
+ if (!strcmp("dirs", optname)) {
+ if (++dirsfound > 1) {
+ printk(KERN_WARNING
+ "unionfs: multiple dirs specified\n");
+ err = -EINVAL;
+ goto out_error;
+ }
+ err = parse_dirs_option(sb, hidden_root_info, optarg);
+ if (err)
+ goto out_error;
+ continue;
+ }
+
+ /* All of these options require an integer argument. */
+ intval = simple_strtoul(optarg, &endptr, 0);
+ if (*endptr) {
+ printk(KERN_WARNING
+ "unionfs: invalid %s option '%s'\n",
+ optname, optarg);
+ err = -EINVAL;
+ goto out_error;
+ }
+
+ err = -EINVAL;
+ printk(KERN_WARNING
+ "unionfs: unrecognized option '%s'\n", optname);
+ goto out_error;
+ }
+ if (dirsfound != 1) {
+ printk(KERN_WARNING "unionfs: dirs option required\n");
+ err = -EINVAL;
+ goto out_error;
+ }
+ goto out;
+
+out_error:
+ if (hidden_root_info && hidden_root_info->lower_paths) {
+ for (bindex = hidden_root_info->bstart;
+ bindex >= 0 && bindex <= hidden_root_info->bend;
+ bindex++) {
+ struct dentry *d;
+ struct vfsmount *m;
+
+ d = hidden_root_info->lower_paths[bindex].dentry;
+ m = hidden_root_info->lower_paths[bindex].mnt;
+
+ dput(d);
+
+ if (m)
+ mntput(m);
+ }
+ }
+
+ kfree(hidden_root_info->lower_paths);
+ kfree(hidden_root_info);
+
+ kfree(UNIONFS_SB(sb)->data);
+ UNIONFS_SB(sb)->data = NULL;
+
+ hidden_root_info = ERR_PTR(err);
+out:
+ return hidden_root_info;
+}
+
+/* our custom d_alloc_root workalike
+ *
+ * we can't use d_alloc_root if we want to use our own interpose function
+ * unchanged, so we simply call our own "fake" d_alloc_root
+ */
+static struct dentry *unionfs_d_alloc_root(struct super_block *sb)
+{
+ struct dentry *ret = NULL;
+
+ if (sb) {
+ static const struct qstr name = {.name = "/",.len = 1 };
+
+ ret = d_alloc(NULL, &name);
+ if (ret) {
+ ret->d_op = &unionfs_dops;
+ ret->d_sb = sb;
+ ret->d_parent = ret;
+ }
+ }
+ return ret;
+}
+
+static int unionfs_read_super(struct super_block *sb, void *raw_data,
+ int silent)
+{
+ int err = 0;
+
+ struct unionfs_dentry_info *hidden_root_info = NULL;
+ int bindex, bstart, bend;
+
+ if (!raw_data) {
+ printk(KERN_WARNING
+ "unionfs_read_super: missing data argument\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * Allocate superblock private data
+ */
+ sb->s_fs_info = kzalloc(sizeof(struct unionfs_sb_info), GFP_KERNEL);
+ if (!UNIONFS_SB(sb)) {
+ printk(KERN_WARNING "%s: out of memory\n", __FUNCTION__);
+ err = -ENOMEM;
+ goto out;
+ }
+
+ UNIONFS_SB(sb)->bend = -1;
+ atomic_set(&UNIONFS_SB(sb)->generation, 1);
+ init_rwsem(&UNIONFS_SB(sb)->rwsem);
+
+ hidden_root_info = unionfs_parse_options(sb, raw_data);
+ if (IS_ERR(hidden_root_info)) {
+ printk(KERN_WARNING
+ "unionfs_read_super: error while parsing options "
+ "(err = %ld)\n", PTR_ERR(hidden_root_info));
+ err = PTR_ERR(hidden_root_info);
+ hidden_root_info = NULL;
+ goto out_free;
+ }
+ if (hidden_root_info->bstart == -1) {
+ err = -ENOENT;
+ goto out_free;
+ }
+
+ /* set the hidden superblock field of upper superblock */
+ bstart = hidden_root_info->bstart;
+ BUG_ON(bstart != 0);
+ sbend(sb) = bend = hidden_root_info->bend;
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ struct dentry *d;
+
+ d = hidden_root_info->lower_paths[bindex].dentry;
+
+ unionfs_set_lower_super_idx(sb, bindex, d->d_sb);
+ }
+
+ /* Unionfs: Max Bytes is the maximum bytes from highest priority branch */
+ sb->s_maxbytes = unionfs_lower_super_idx(sb, 0)->s_maxbytes;
+
+ sb->s_op = &unionfs_sops;
+
+ /* See comment next to the definition of unionfs_d_alloc_root */
+ sb->s_root = unionfs_d_alloc_root(sb);
+ if (!sb->s_root) {
+ err = -ENOMEM;
+ goto out_dput;
+ }
+
+ /* link the upper and lower dentries */
+ sb->s_root->d_fsdata = NULL;
+ if ((err = new_dentry_private_data(sb->s_root)))
+ goto out_freedpd;
+
+ /* Set the hidden dentries for s_root */
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ struct dentry *d;
+ struct vfsmount *m;
+
+ d = hidden_root_info->lower_paths[bindex].dentry;
+ m = hidden_root_info->lower_paths[bindex].mnt;
+
+ unionfs_set_lower_dentry_idx(sb->s_root, bindex, d);
+ unionfs_set_lower_mnt_idx(sb->s_root, bindex, m);
+ }
+ set_dbstart(sb->s_root, bstart);
+ set_dbend(sb->s_root, bend);
+
+ /* Set the generation number to one, since this is for the mount. */
+ atomic_set(&UNIONFS_D(sb->s_root)->generation, 1);
+
+ /* call interpose to create the upper level inode */
+ if ((err = unionfs_interpose(sb->s_root, sb, 0)))
+ goto out_freedpd;
+ unlock_dentry(sb->s_root);
+ goto out;
+
+out_freedpd:
+ if (UNIONFS_D(sb->s_root)) {
+ kfree(UNIONFS_D(sb->s_root)->lower_paths);
+ free_dentry_private_data(UNIONFS_D(sb->s_root));
+ }
+ dput(sb->s_root);
+
+out_dput:
+ if (hidden_root_info && !IS_ERR(hidden_root_info)) {
+ for (bindex = hidden_root_info->bstart;
+ bindex <= hidden_root_info->bend; bindex++) {
+ struct dentry *d;
+ struct vfsmount *m;
+
+ d = hidden_root_info->lower_paths[bindex].dentry;
+ m = hidden_root_info->lower_paths[bindex].mnt;
+
+ dput(d);
+ mntput(m);
+ }
+ kfree(hidden_root_info->lower_paths);
+ kfree(hidden_root_info);
+ hidden_root_info = NULL;
+ }
+
+out_free:
+ kfree(UNIONFS_SB(sb)->data);
+ kfree(UNIONFS_SB(sb));
+ sb->s_fs_info = NULL;
+
+out:
+ if (hidden_root_info && !IS_ERR(hidden_root_info)) {
+ kfree(hidden_root_info->lower_paths);
+ kfree(hidden_root_info);
+ }
+ return err;
+}
+
+static int unionfs_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name,
+ void *raw_data, struct vfsmount *mnt)
+{
+ return get_sb_nodev(fs_type, flags, raw_data, unionfs_read_super, mnt);
+}
+
+static struct file_system_type unionfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "unionfs",
+ .get_sb = unionfs_get_sb,
+ .kill_sb = generic_shutdown_super,
+ .fs_flags = FS_REVAL_DOT,
+};
+
+static int init_debug = 0;
+module_param_named(debug, init_debug, int, S_IRUGO);
+MODULE_PARM_DESC(debug, "Initial Unionfs debug value.");
+
+static int __init init_unionfs_fs(void)
+{
+ int err;
+ printk("Registering unionfs " UNIONFS_VERSION "\n");
+
+ if ((err = init_filldir_cache()))
+ goto out;
+ if ((err = init_inode_cache()))
+ goto out;
+ if ((err = init_dentry_cache()))
+ goto out;
+ if ((err = init_sioq()))
+ goto out;
+ err = register_filesystem(&unionfs_fs_type);
+out:
+ if (err) {
+ fin_sioq();
+ destroy_filldir_cache();
+ destroy_inode_cache();
+ destroy_dentry_cache();
+ }
+ return err;
+}
+static void __exit exit_unionfs_fs(void)
+{
+ fin_sioq();
+ destroy_filldir_cache();
+ destroy_inode_cache();
+ destroy_dentry_cache();
+ unregister_filesystem(&unionfs_fs_type);
+ printk("Completed unionfs module unload.\n");
+}
+
+MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
+ " (http://www.fsl.cs.sunysb.edu)");
+MODULE_DESCRIPTION("Unionfs " UNIONFS_VERSION
+ " (http://www.unionfs.org)");
+MODULE_LICENSE("GPL");
+
+module_init(init_unionfs_fs);
+module_exit(exit_unionfs_fs);
+
--
1.4.3.3
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