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Subject[PATCH 18/35] Unionfs: File operations
Date
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

This patch provides the file 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/file.c | 258 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 258 insertions(+), 0 deletions(-)
diff --git a/fs/unionfs/file.c b/fs/unionfs/file.c
new file mode 100644
index 0000000..3dc9f8f
--- /dev/null
+++ b/fs/unionfs/file.c
@@ -0,0 +1,258 @@
+/*
+ * 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 for sparse */
+extern ssize_t unionfs_read(struct file *, char __user *, size_t, loff_t *);
+extern ssize_t unionfs_write(struct file *, const char __user *, size_t,
+ loff_t *);
+
+/*******************
+ * File Operations *
+ *******************/
+
+static loff_t unionfs_llseek(struct file *file, loff_t offset, int origin)
+{
+ loff_t err;
+ struct file *hidden_file = NULL;
+
+ if ((err = unionfs_file_revalidate(file, 0)))
+ goto out;
+
+ hidden_file = unionfs_lower_file(file);
+ /* always set hidden position to this one */
+ hidden_file->f_pos = file->f_pos;
+
+ memcpy(&hidden_file->f_ra, &file->f_ra, sizeof(struct file_ra_state));
+
+ if (hidden_file->f_op && hidden_file->f_op->llseek)
+ err = hidden_file->f_op->llseek(hidden_file, offset, origin);
+ else
+ err = generic_file_llseek(hidden_file, offset, origin);
+
+ if (err < 0)
+ goto out;
+ if (err != file->f_pos) {
+ file->f_pos = err;
+ file->f_version++;
+ }
+out:
+ return err;
+}
+
+ssize_t unionfs_read(struct file * file, char __user * buf, size_t count,
+ loff_t * ppos)
+{
+ struct file *hidden_file;
+ loff_t pos = *ppos;
+ int err;
+
+ if ((err = unionfs_file_revalidate(file, 0)))
+ goto out;
+
+ err = -EINVAL;
+ hidden_file = unionfs_lower_file(file);
+ if (!hidden_file->f_op || !hidden_file->f_op->read)
+ goto out;
+
+ err = hidden_file->f_op->read(hidden_file, buf, count, &pos);
+ *ppos = pos;
+
+out:
+ return err;
+}
+
+ssize_t __unionfs_write(struct file * file, const char __user * buf,
+ size_t count, loff_t * ppos)
+{
+ int err = -EINVAL;
+ struct file *hidden_file = NULL;
+ struct inode *inode;
+ struct inode *hidden_inode;
+ loff_t pos = *ppos;
+ int bstart, bend;
+
+ inode = file->f_dentry->d_inode;
+
+ bstart = fbstart(file);
+ bend = fbend(file);
+
+ BUG_ON(bstart == -1);
+
+ hidden_file = unionfs_lower_file(file);
+ hidden_inode = hidden_file->f_dentry->d_inode;
+
+ if (!hidden_file->f_op || !hidden_file->f_op->write)
+ goto out;
+
+ /* adjust for append -- seek to the end of the file */
+ if (file->f_flags & O_APPEND)
+ pos = inode->i_size;
+
+ err = hidden_file->f_op->write(hidden_file, buf, count, &pos);
+
+ /*
+ * copy ctime and mtime from lower layer attributes
+ * atime is unchanged for both layers
+ */
+ if (err >= 0)
+ fsstack_copy_attr_times(inode, hidden_inode);
+
+ *ppos = pos;
+
+ /* update this inode's size */
+ if (pos > inode->i_size)
+ inode->i_size = pos;
+out:
+ return err;
+}
+
+ssize_t unionfs_write(struct file * file, const char __user * buf, size_t count,
+ loff_t * ppos)
+{
+ int err = 0;
+
+ if ((err = unionfs_file_revalidate(file, 1)))
+ goto out;
+
+ err = __unionfs_write(file, buf, count, ppos);
+
+out:
+ return err;
+}
+
+static int unionfs_file_readdir(struct file *file, void *dirent,
+ filldir_t filldir)
+{
+ return -ENOTDIR;
+}
+
+static unsigned int unionfs_poll(struct file *file, poll_table * wait)
+{
+ unsigned int mask = DEFAULT_POLLMASK;
+ struct file *hidden_file = NULL;
+
+ if (unionfs_file_revalidate(file, 0)) {
+ /* We should pretend an error happend. */
+ mask = POLLERR | POLLIN | POLLOUT;
+ goto out;
+ }
+
+ hidden_file = unionfs_lower_file(file);
+
+ if (!hidden_file->f_op || !hidden_file->f_op->poll)
+ goto out;
+
+ mask = hidden_file->f_op->poll(hidden_file, wait);
+
+out:
+ return mask;
+}
+
+static int __do_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int err;
+ struct file *hidden_file;
+
+ hidden_file = unionfs_lower_file(file);
+
+ err = -ENODEV;
+ if (!hidden_file->f_op || !hidden_file->f_op->mmap)
+ goto out;
+
+ vma->vm_file = hidden_file;
+ err = hidden_file->f_op->mmap(hidden_file, vma);
+ get_file(hidden_file); /* make sure it doesn't get freed on us */
+ fput(file); /* no need to keep extra ref on ours */
+out:
+ return err;
+}
+
+static int unionfs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int err = 0;
+ int willwrite;
+
+ /* This might could be deferred to mmap's writepage. */
+ willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
+ if ((err = unionfs_file_revalidate(file, willwrite)))
+ goto out;
+
+ err = __do_mmap(file, vma);
+
+out:
+ return err;
+}
+
+static int unionfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+ int err;
+ struct file *hidden_file = NULL;
+
+ if ((err = unionfs_file_revalidate(file, 1)))
+ goto out;
+
+ hidden_file = unionfs_lower_file(file);
+
+ err = -EINVAL;
+ if (!hidden_file->f_op || !hidden_file->f_op->fsync)
+ goto out;
+
+ mutex_lock(&hidden_file->f_dentry->d_inode->i_mutex);
+ err = hidden_file->f_op->fsync(hidden_file, hidden_file->f_dentry,
+ datasync);
+ mutex_unlock(&hidden_file->f_dentry->d_inode->i_mutex);
+
+out:
+ return err;
+}
+
+/* SP: disabled as none of the other in kernel fs's seem to use it */
+static int unionfs_fasync(int fd, struct file *file, int flag)
+{
+ int err = 0;
+ struct file *hidden_file = NULL;
+
+ if ((err = unionfs_file_revalidate(file, 1)))
+ goto out;
+
+ hidden_file = unionfs_lower_file(file);
+
+ if (hidden_file->f_op && hidden_file->f_op->fasync)
+ err = hidden_file->f_op->fasync(fd, hidden_file, flag);
+
+out:
+ return err;
+}
+
+struct file_operations unionfs_main_fops = {
+ .llseek = unionfs_llseek,
+ .read = unionfs_read,
+ .write = unionfs_write,
+ .readdir = unionfs_file_readdir,
+ .poll = unionfs_poll,
+ .unlocked_ioctl = unionfs_ioctl,
+ .mmap = unionfs_mmap,
+ .open = unionfs_open,
+ .flush = unionfs_flush,
+ .release = unionfs_file_release,
+ .fsync = unionfs_fsync,
+ .fasync = unionfs_fasync,
+};
+
--
1.4.3.3
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