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Subject[PATCH 02/14] Pramfs: File operations for directories
From: Marco Stornelli <marco.stornelli@gmail.com>

File operations for directories.

Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
---
diff -uprN linux-2.6.30-orig/fs/pramfs/dir.c linux-2.6.30/fs/pramfs/dir.c
--- linux-2.6.30-orig/fs/pramfs/dir.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.30/fs/pramfs/dir.c 2009-06-13 12:51:46.000000000 +0200
@@ -0,0 +1,220 @@
+/*
+ * FILE NAME fs/pramfs/dir.c
+ *
+ * BRIEF DESCRIPTION
+ *
+ * File operations for directories.
+ *
+ * Copyright 2009 Marco Stornelli <marco.stornelli@gmail.com>
+ * Copyright 2003 Sony Corporation
+ * Copyright 2003 Matsushita Electric Industrial Co., Ltd.
+ * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include "pram_fs.h"
+
+/*
+ * Parent is locked.
+ */
+int pram_add_link(struct dentry *dentry, struct inode *inode)
+{
+ struct inode *dir = dentry->d_parent->d_inode;
+ struct pram_inode *pidir, *pi, *pitail = NULL;
+ off_t tail_ino, prev_ino;
+ unsigned long flags;
+
+ const char *name = dentry->d_name.name;
+ int namelen = dentry->d_name.len > PRAM_NAME_LEN ?
+ PRAM_NAME_LEN : dentry->d_name.len;
+
+ flags = 0;
+
+ pidir = pram_get_inode(dir->i_sb, dir->i_ino);
+ pi = pram_get_inode(dir->i_sb, inode->i_ino);
+
+ dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+
+ tail_ino = pidir->i_type.dir.tail;
+ if (tail_ino != 0) {
+ pitail = pram_get_inode(dir->i_sb, tail_ino);
+ pram_lock_inode(pitail, flags);
+ pitail->i_d.d_next = inode->i_ino;
+ pram_unlock_inode(pitail, flags);
+
+ prev_ino = tail_ino;
+
+ pram_lock_inode(pidir, flags);
+ pidir->i_type.dir.tail = inode->i_ino;
+ pidir->i_mtime = dir->i_mtime.tv_sec;
+ pidir->i_ctime = dir->i_ctime.tv_sec;
+ pram_unlock_inode(pidir, flags);
+ } else {
+ /* the directory is empty */
+ prev_ino = 0;
+
+ pram_lock_inode(pidir, flags);
+ pidir->i_type.dir.head = pidir->i_type.dir.tail = inode->i_ino;
+ pidir->i_mtime = dir->i_mtime.tv_sec;
+ pidir->i_ctime = dir->i_ctime.tv_sec;
+ pram_unlock_inode(pidir, flags);
+ }
+
+
+ pram_lock_inode(pi, flags);
+ pi->i_d.d_prev = prev_ino;
+ pi->i_d.d_parent = dir->i_ino;
+ memcpy(pi->i_d.d_name, name, namelen);
+ pi->i_d.d_name[namelen] = '\0';
+ pram_unlock_inode(pi, flags);
+ return 0;
+}
+
+int pram_remove_link(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+ struct pram_inode *prev = NULL;
+ struct pram_inode *next = NULL;
+ struct pram_inode *pidir, *pi;
+ unsigned long flags;
+
+ flags = 0;
+
+ pi = pram_get_inode(sb, inode->i_ino);
+ pidir = pram_get_inode(sb, pi->i_d.d_parent);
+ if (!pidir)
+ return -EACCES;
+
+ if (inode->i_ino == pidir->i_type.dir.head) {
+ /* first inode in directory */
+ next = pram_get_inode(sb, pi->i_d.d_next);
+
+ if (next) {
+ pram_lock_inode(next, flags);
+ next->i_d.d_prev = 0;
+ pram_unlock_inode(next, flags);
+
+ pram_lock_inode(pidir, flags);
+ pidir->i_type.dir.head = pi->i_d.d_next;
+ } else {
+ pram_lock_inode(pidir, flags);
+ pidir->i_type.dir.head = pidir->i_type.dir.tail = 0;
+ }
+ pram_unlock_inode(pidir, flags);
+ } else if (inode->i_ino == pidir->i_type.dir.tail) {
+ /* last inode in directory */
+ prev = pram_get_inode(sb, pi->i_d.d_prev);
+
+ pram_lock_inode(prev, flags);
+ prev->i_d.d_next = 0;
+ pram_unlock_inode(prev, flags);
+
+ pram_lock_inode(pidir, flags);
+ pidir->i_type.dir.tail = pi->i_d.d_prev;
+ pram_unlock_inode(pidir, flags);
+ } else {
+ /* somewhere in the middle */
+ prev = pram_get_inode(sb, pi->i_d.d_prev);
+ next = pram_get_inode(sb, pi->i_d.d_next);
+
+ if (prev && next) {
+ pram_lock_inode(prev, flags);
+ prev->i_d.d_next = pi->i_d.d_next;
+ pram_unlock_inode(prev, flags);
+
+ pram_lock_inode(next, flags);
+ next->i_d.d_prev = pi->i_d.d_prev;
+ pram_unlock_inode(next, flags);
+ }
+ }
+
+ pram_lock_inode(pi, flags);
+ pi->i_d.d_next = pi->i_d.d_prev = pi->i_d.d_parent = 0;
+ pram_unlock_inode(pi, flags);
+
+ return 0;
+}
+
+#define S_SHIFT 12
+static unsigned int dtype_by_mode[S_IFMT >> S_SHIFT] = {
+ [S_IFREG >> S_SHIFT] DT_REG,
+ [S_IFDIR >> S_SHIFT] DT_DIR,
+ [S_IFCHR >> S_SHIFT] DT_CHR,
+ [S_IFBLK >> S_SHIFT] DT_BLK,
+ [S_IFIFO >> S_SHIFT] DT_FIFO,
+ [S_IFSOCK >> S_SHIFT] DT_SOCK,
+ [S_IFLNK >> S_SHIFT] DT_LNK,
+};
+
+static int
+pram_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+ struct inode *inode = filp->f_dentry->d_inode;
+ struct super_block *sb = inode->i_sb;
+ struct pram_inode *pi;
+ int namelen, ret = 0;
+ char *name;
+ ino_t ino;
+
+ if (filp->f_pos >> 32)
+ return 0;
+
+ pi = pram_get_inode(sb, inode->i_ino);
+
+ switch ((unsigned long)filp->f_pos) {
+ case 0:
+ ret = filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR);
+ filp->f_pos++;
+ return ret;
+ case 1:
+ ret = filldir(dirent, "..", 2, 1, pi->i_d.d_parent, DT_DIR);
+ ino = pi->i_type.dir.head;
+ filp->f_pos = ino ? ino : 2;
+ return ret;
+ case 2:
+ ino = pi->i_type.dir.head;
+ if (ino) {
+ filp->f_pos = ino;
+ pi = pram_get_inode(sb, ino);
+ break;
+ } else {
+ /* the directory is empty */
+ filp->f_pos = 2;
+ return 0;
+ }
+ case 3:
+ return 0;
+ default:
+ ino = filp->f_pos;
+ pi = pram_get_inode(sb, ino);
+ break;
+ }
+
+ while (pi && !pi->i_links_count) {
+ ino = filp->f_pos = pi->i_d.d_next;
+ pi = pram_get_inode(sb, ino);
+ }
+
+ if (pi) {
+ name = pi->i_d.d_name;
+ namelen = strlen(name);
+
+ ret = filldir(dirent, name, namelen,
+ filp->f_pos, ino,
+ dtype_by_mode[(pi->i_mode & S_IFMT)>>S_SHIFT]);
+ filp->f_pos = pi->i_d.d_next ? pi->i_d.d_next : 3;
+ } else
+ filp->f_pos = 3;
+
+ return ret;
+}
+
+struct file_operations pram_dir_operations = {
+ .read = generic_read_dir,
+ .readdir = pram_readdir,
+ .fsync = simple_sync_file,
+};


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