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Subject[PATCH 8 of 23] Unionfs: Directory file operations
Date
From
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

This patch provides directory file operations.

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, 263 insertions(+)
fs/unionfs/dirfops.c | 263 ++++++++++++++++++++++++++++++++++++++++++++++++++
diff -r b699f4b2c3a5 -r 9ebbf5515984 fs/unionfs/dirfops.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/fs/unionfs/dirfops.c Sat Oct 07 00:46:18 2006 -0400
@@ -0,0 +1,263 @@
+/*
+ * 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"
+
+/* Make sure our rdstate is playing by the rules. */
+static void verify_rdstate_offset(struct unionfs_dir_state *rdstate)
+{
+ BUG_ON(rdstate->uds_offset >= DIREOF);
+ BUG_ON(rdstate->uds_cookie >= MAXRDCOOKIE);
+}
+
+struct unionfs_getdents_callback {
+ struct unionfs_dir_state *rdstate;
+ void *dirent;
+ int entries_written;
+ int filldir_called;
+ int filldir_error;
+ filldir_t filldir;
+ struct super_block *sb;
+};
+
+/* copied from generic filldir in fs/readir.c */
+static int unionfs_filldir(void *dirent, const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
+{
+ struct unionfs_getdents_callback *buf = dirent;
+ struct filldir_node *found = NULL;
+ int err = 0;
+ int is_wh_entry = 0;
+
+ buf->filldir_called++;
+
+ if ((namelen > UNIONFS_WHLEN) && !strncmp(name, UNIONFS_WHPFX, UNIONFS_WHLEN)) {
+ name += UNIONFS_WHLEN;
+ namelen -= UNIONFS_WHLEN;
+ is_wh_entry = 1;
+ }
+
+ found = find_filldir_node(buf->rdstate, name, namelen);
+
+ if (found)
+ goto out;
+
+ /* if 'name' isn't a whiteout, filldir it. */
+ if (!is_wh_entry) {
+ off_t pos = rdstate2offset(buf->rdstate);
+ u64 unionfs_ino = ino;
+
+ if (!err) {
+ err = buf->filldir(buf->dirent, name, namelen, pos,
+ unionfs_ino, d_type);
+ buf->rdstate->uds_offset++;
+ verify_rdstate_offset(buf->rdstate);
+ }
+ }
+ /* If we did fill it, stuff it in our hash, otherwise return an error */
+ if (err) {
+ buf->filldir_error = err;
+ goto out;
+ }
+ buf->entries_written++;
+ if ((err = add_filldir_node(buf->rdstate, name, namelen,
+ buf->rdstate->uds_bindex, is_wh_entry)))
+ buf->filldir_error = err;
+
+out:
+ return err;
+}
+
+static int unionfs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+ int err = 0;
+ struct file *hidden_file = NULL;
+ struct inode *inode = NULL;
+ struct unionfs_getdents_callback buf;
+ struct unionfs_dir_state *uds;
+ int bend;
+ loff_t offset;
+
+ if ((err = unionfs_file_revalidate(file, 0)))
+ goto out;
+
+ inode = file->f_dentry->d_inode;
+
+ uds = ftopd(file)->rdstate;
+ if (!uds) {
+ if (file->f_pos == DIREOF) {
+ goto out;
+ } else if (file->f_pos > 0) {
+ uds = find_rdstate(inode, file->f_pos);
+ if (!uds) {
+ err = -ESTALE;
+ goto out;
+ }
+ ftopd(file)->rdstate = uds;
+ } else {
+ init_rdstate(file);
+ uds = ftopd(file)->rdstate;
+ }
+ }
+ bend = fbend(file);
+
+ while (uds->uds_bindex <= bend) {
+ hidden_file = ftohf_index(file, uds->uds_bindex);
+ if (!hidden_file) {
+ uds->uds_bindex++;
+ uds->uds_dirpos = 0;
+ continue;
+ }
+
+ /* prepare callback buffer */
+ buf.filldir_called = 0;
+ buf.filldir_error = 0;
+ buf.entries_written = 0;
+ buf.dirent = dirent;
+ buf.filldir = filldir;
+ buf.rdstate = uds;
+ buf.sb = inode->i_sb;
+
+ /* Read starting from where we last left off. */
+ offset = vfs_llseek(hidden_file, uds->uds_dirpos, 0);
+ if (offset < 0) {
+ err = offset;
+ goto out;
+ }
+ err = vfs_readdir(hidden_file, unionfs_filldir, &buf);
+ /* Save the position for when we continue. */
+
+ offset = vfs_llseek(hidden_file, 0, 1);
+ if (offset < 0) {
+ err = offset;
+ goto out;
+ }
+ uds->uds_dirpos = offset;
+
+ /* Copy the atime. */
+ fist_copy_attr_atime(inode, hidden_file->f_dentry->d_inode);
+
+ if (err < 0)
+ goto out;
+
+ if (buf.filldir_error)
+ break;
+
+ if (!buf.entries_written) {
+ uds->uds_bindex++;
+ uds->uds_dirpos = 0;
+ }
+ }
+
+ if (!buf.filldir_error && uds->uds_bindex >= bend) {
+ /* Save the number of hash entries for next time. */
+ itopd(inode)->uii_hashsize = uds->uds_hashentries;
+ free_rdstate(uds);
+ ftopd(file)->rdstate = NULL;
+ file->f_pos = DIREOF;
+ } else
+ file->f_pos = rdstate2offset(uds);
+
+out:
+ return err;
+}
+
+/* This is not meant to be a generic repositioning function. If you do
+ * things that aren't supported, then we return EINVAL.
+ *
+ * What is allowed:
+ * (1) seeking to the same position that you are currently at
+ * This really has no effect, but returns where you are.
+ * (2) seeking to the end of the file, if you've read everything
+ * This really has no effect, but returns where you are.
+ * (3) seeking to the beginning of the file
+ * This throws out all state, and lets you begin again.
+ */
+static loff_t unionfs_dir_llseek(struct file *file, loff_t offset, int origin)
+{
+ struct unionfs_dir_state *rdstate;
+ loff_t err;
+
+ if ((err = unionfs_file_revalidate(file, 0)))
+ goto out;
+
+ rdstate = ftopd(file)->rdstate;
+
+ /* We let users seek to their current position, but not anywhere else. */
+ if (!offset) {
+ switch (origin) {
+ case SEEK_SET:
+ if (rdstate) {
+ free_rdstate(rdstate);
+ ftopd(file)->rdstate = NULL;
+ }
+ init_rdstate(file);
+ err = 0;
+ break;
+ case SEEK_CUR:
+ err = file->f_pos;
+ break;
+ case SEEK_END:
+ /* Unsupported, because we would break everything. */
+ err = -EINVAL;
+ break;
+ }
+ } else {
+ switch (origin) {
+ case SEEK_SET:
+ if (rdstate) {
+ if (offset == rdstate2offset(rdstate))
+ err = offset;
+ else if (file->f_pos == DIREOF)
+ err = DIREOF;
+ else
+ err = -EINVAL;
+ } else {
+ if ((rdstate = find_rdstate(file->f_dentry->d_inode,
+ offset))) {
+ ftopd(file)->rdstate = rdstate;
+ err = rdstate->uds_offset;
+ } else
+ err = -EINVAL;
+ }
+ break;
+ case SEEK_CUR:
+ case SEEK_END:
+ /* Unsupported, because we would break everything. */
+ err = -EINVAL;
+ break;
+ }
+ }
+
+out:
+ return err;
+}
+
+/* Trimmed directory options, we shouldn't pass everything down since
+ * we don't want to operate on partial directories.
+ */
+struct file_operations unionfs_dir_fops = {
+ .llseek = unionfs_dir_llseek,
+ .read = generic_read_dir,
+ .readdir = unionfs_readdir,
+ .unlocked_ioctl = unionfs_ioctl,
+ .open = unionfs_open,
+ .release = unionfs_file_release,
+ .flush = unionfs_flush,
+};
+

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