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Subject[PATCH 13 of 23] Unionfs: Readdir state
Date
From
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

This file contains the routines for maintaining readdir state.

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>

---
1 file changed, 295 insertions(+)
fs/unionfs/rdstate.c | 295 ++++++++++++++++++++++++++++++++++++++++++++++++++
diff -r e107be2f4ead -r 28ddedcd7cbe fs/unionfs/rdstate.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/fs/unionfs/rdstate.c Sat Oct 07 00:46:19 2006 -0400
@@ -0,0 +1,295 @@
+/*
+ * 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"
+
+/* This file contains the routines for maintaining readdir state. */
+/* There are two structures here, rdstate which is a hash table
+ * of the second structure which is a filldir_node. */
+
+/* This is a kmem_cache_t for filldir nodes, because we allocate a lot of them
+ * and they shouldn't waste memory. If the node has a small name (as defined
+ * by the dentry structure), then we use an inline name to preserve kmalloc
+ * space. */
+static kmem_cache_t *unionfs_filldir_cachep;
+int init_filldir_cache(void)
+{
+ unionfs_filldir_cachep =
+ kmem_cache_create("unionfs_filldir", sizeof(struct filldir_node), 0,
+ SLAB_RECLAIM_ACCOUNT, NULL, NULL);
+
+ if (!unionfs_filldir_cachep)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void destroy_filldir_cache(void)
+{
+ if (unionfs_filldir_cachep)
+ kmem_cache_destroy(unionfs_filldir_cachep);
+}
+
+/* This is a tuning parameter that tells us roughly how big to make the
+ * hash table in directory entries per page. This isn't perfect, but
+ * at least we get a hash table size that shouldn't be too overloaded.
+ * The following averages are based on my home directory.
+ * 14.44693 Overall
+ * 12.29 Single Page Directories
+ * 117.93 Multi-page directories
+ */
+#define DENTPAGE 4096
+#define DENTPERONEPAGE 12
+#define DENTPERPAGE 118
+#define MINHASHSIZE 1
+static int guesstimate_hash_size(struct inode *inode)
+{
+ struct inode *hidden_inode;
+ int bindex;
+ int hashsize = MINHASHSIZE;
+
+ if (itopd(inode)->uii_hashsize > 0)
+ return itopd(inode)->uii_hashsize;
+
+ for (bindex = ibstart(inode); bindex <= ibend(inode); bindex++) {
+ if (!(hidden_inode = itohi_index(inode, bindex)))
+ continue;
+
+ if (hidden_inode->i_size == DENTPAGE) {
+ hashsize += DENTPERONEPAGE;
+ } else {
+ hashsize +=
+ (hidden_inode->i_size / DENTPAGE) * DENTPERPAGE;
+ }
+ }
+
+ return hashsize;
+}
+
+int init_rdstate(struct file *file)
+{
+ BUG_ON(sizeof(loff_t) != (sizeof(unsigned int) + sizeof(unsigned int)));
+ BUG_ON(ftopd(file)->rdstate != NULL);
+
+ ftopd(file)->rdstate =
+ alloc_rdstate(file->f_dentry->d_inode, fbstart(file));
+ if (!ftopd(file)->rdstate)
+ return -ENOMEM;
+ return 0;
+}
+
+struct unionfs_dir_state *find_rdstate(struct inode *inode, loff_t fpos)
+{
+ struct unionfs_dir_state *rdstate = NULL;
+ struct list_head *pos;
+
+ spin_lock(&itopd(inode)->uii_rdlock);
+ list_for_each(pos, &itopd(inode)->uii_readdircache) {
+ struct unionfs_dir_state *r =
+ list_entry(pos, struct unionfs_dir_state, uds_cache);
+ if (fpos == rdstate2offset(r)) {
+ itopd(inode)->uii_rdcount--;
+ list_del(&r->uds_cache);
+ rdstate = r;
+ break;
+ }
+ }
+ spin_unlock(&itopd(inode)->uii_rdlock);
+ return rdstate;
+}
+
+struct unionfs_dir_state *alloc_rdstate(struct inode *inode, int bindex)
+{
+ int i = 0;
+ int hashsize;
+ int mallocsize = sizeof(struct unionfs_dir_state);
+ struct unionfs_dir_state *rdstate;
+
+ hashsize = guesstimate_hash_size(inode);
+ mallocsize += hashsize * sizeof(struct list_head);
+ /* Round it up to the next highest power of two. */
+ mallocsize--;
+ mallocsize |= mallocsize >> 1;
+ mallocsize |= mallocsize >> 2;
+ mallocsize |= mallocsize >> 4;
+ mallocsize |= mallocsize >> 8;
+ mallocsize |= mallocsize >> 16;
+ mallocsize++;
+
+ /* This should give us about 500 entries anyway. */
+ if (mallocsize > PAGE_SIZE)
+ mallocsize = PAGE_SIZE;
+
+ hashsize =
+ (mallocsize -
+ sizeof(struct unionfs_dir_state)) / sizeof(struct list_head);
+
+ rdstate = kmalloc(mallocsize, GFP_KERNEL);
+ if (!rdstate)
+ return NULL;
+
+ spin_lock(&itopd(inode)->uii_rdlock);
+ if (itopd(inode)->uii_cookie >= (MAXRDCOOKIE - 1))
+ itopd(inode)->uii_cookie = 1;
+ else
+ itopd(inode)->uii_cookie++;
+
+ rdstate->uds_cookie = itopd(inode)->uii_cookie;
+ spin_unlock(&itopd(inode)->uii_rdlock);
+ rdstate->uds_offset = 1;
+ rdstate->uds_access = jiffies;
+ rdstate->uds_bindex = bindex;
+ rdstate->uds_dirpos = 0;
+ rdstate->uds_hashentries = 0;
+ rdstate->uds_size = hashsize;
+ for (i = 0; i < rdstate->uds_size; i++)
+ INIT_LIST_HEAD(&rdstate->uds_list[i]);
+
+ return rdstate;
+}
+
+static void free_filldir_node(struct filldir_node *node)
+{
+ if (node->namelen >= DNAME_INLINE_LEN_MIN)
+ kfree(node->name);
+ kmem_cache_free(unionfs_filldir_cachep, node);
+}
+
+void free_rdstate(struct unionfs_dir_state *state)
+{
+ struct filldir_node *tmp;
+ int i;
+
+ for (i = 0; i < state->uds_size; i++) {
+ struct list_head *head = &(state->uds_list[i]);
+ struct list_head *pos, *n;
+
+ /* traverse the list and deallocate space */
+ list_for_each_safe(pos, n, head) {
+ tmp = list_entry(pos, struct filldir_node, file_list);
+ list_del(&tmp->file_list);
+ free_filldir_node(tmp);
+ }
+ }
+
+ kfree(state);
+}
+
+struct filldir_node *find_filldir_node(struct unionfs_dir_state *rdstate,
+ const char *name, int namelen)
+{
+ int index;
+ unsigned int hash;
+ struct list_head *head;
+ struct list_head *pos;
+ struct filldir_node *cursor = NULL;
+ int found = 0;
+
+ BUG_ON(namelen <= 0);
+
+ hash = full_name_hash(name, namelen);
+ index = hash % rdstate->uds_size;
+
+ head = &(rdstate->uds_list[index]);
+ list_for_each(pos, head) {
+ cursor = list_entry(pos, struct filldir_node, file_list);
+
+ if (cursor->namelen == namelen && cursor->hash == hash
+ && !strncmp(cursor->name, name, namelen)) {
+ /* a duplicate exists, and hence no need to create entry to the list */
+ found = 1;
+ /* if the duplicate is in this branch, then the file system is corrupted. */
+ if (cursor->bindex == rdstate->uds_bindex) {
+ //buf->error = err = -EIO;
+ printk(KERN_DEBUG
+ "Possible I/O error unionfs_filldir: a file is duplicated in the same branch %d: %s\n",
+ rdstate->uds_bindex, cursor->name);
+ }
+ break;
+ }
+ }
+
+ if (!found) {
+ cursor = NULL;
+ }
+ return cursor;
+}
+
+inline struct filldir_node *alloc_filldir_node(const char *name, int namelen,
+ unsigned int hash, int bindex)
+{
+ struct filldir_node *newnode;
+
+ newnode =
+ (struct filldir_node *)kmem_cache_alloc(unionfs_filldir_cachep,
+ SLAB_KERNEL);
+ if (!newnode)
+ goto out;
+
+out:
+ return newnode;
+}
+
+int add_filldir_node(struct unionfs_dir_state *rdstate, const char *name,
+ int namelen, int bindex, int whiteout)
+{
+ struct filldir_node *new;
+ unsigned int hash;
+ int index;
+ int err = 0;
+ struct list_head *head;
+
+ BUG_ON(namelen <= 0);
+
+ hash = full_name_hash(name, namelen);
+ index = hash % rdstate->uds_size;
+ head = &(rdstate->uds_list[index]);
+
+ new = alloc_filldir_node(name, namelen, hash, bindex);
+ if (!new) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ INIT_LIST_HEAD(&new->file_list);
+ new->namelen = namelen;
+ new->hash = hash;
+ new->bindex = bindex;
+ new->whiteout = whiteout;
+
+ if (namelen < DNAME_INLINE_LEN_MIN) {
+ new->name = new->iname;
+ } else {
+ new->name = kmalloc(namelen + 1, GFP_KERNEL);
+ if (!new->name) {
+ kmem_cache_free(unionfs_filldir_cachep, new);
+ new = NULL;
+ goto out;
+ }
+ }
+
+ memcpy(new->name, name, namelen);
+ new->name[namelen] = '\0';
+
+ rdstate->uds_hashentries++;
+
+ list_add(&(new->file_list), head);
+out:
+ return err;
+}
+

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