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Subject[PATCH 13/42] Unionfs: basic file operations
Date
Includes read, write, mmap, fsync, and fasync.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
fs/unionfs/file.c | 227 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 227 insertions(+), 0 deletions(-)
create mode 100644 fs/unionfs/file.c
diff --git a/fs/unionfs/file.c b/fs/unionfs/file.c
new file mode 100644
index 0000000..c922173
--- /dev/null
+++ b/fs/unionfs/file.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright (c) 2003-2007 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2007 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) 2003-2007 Stony Brook University
+ * Copyright (c) 2003-2007 The Research Foundation of SUNY
+ *
+ * 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"
+
+static ssize_t unionfs_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ int err;
+
+ unionfs_read_lock(file->f_path.dentry->d_sb);
+ err = unionfs_file_revalidate(file, false);
+ if (unlikely(err))
+ goto out;
+ unionfs_check_file(file);
+
+ err = do_sync_read(file, buf, count, ppos);
+
+out:
+ unionfs_check_file(file);
+ unionfs_read_unlock(file->f_path.dentry->d_sb);
+ return err;
+}
+
+static ssize_t unionfs_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ int err = 0;
+
+ unionfs_read_lock(file->f_path.dentry->d_sb);
+ err = unionfs_file_revalidate(file, true);
+ if (unlikely(err))
+ goto out;
+ unionfs_check_file(file);
+
+ err = do_sync_write(file, buf, count, ppos);
+ /* update our inode times upon a successful lower write */
+ if (err >= 0) {
+ unionfs_copy_attr_times(file->f_path.dentry->d_inode);
+ unionfs_check_file(file);
+ }
+
+out:
+ unionfs_read_unlock(file->f_path.dentry->d_sb);
+ return err;
+}
+
+static int unionfs_file_readdir(struct file *file, void *dirent,
+ filldir_t filldir)
+{
+ return -ENOTDIR;
+}
+
+static int unionfs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int err = 0;
+ bool willwrite;
+ struct file *lower_file;
+
+ unionfs_read_lock(file->f_path.dentry->d_sb);
+
+ /* This might be deferred to mmap's writepage */
+ willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
+ err = unionfs_file_revalidate(file, willwrite);
+ if (unlikely(err))
+ goto out;
+ unionfs_check_file(file);
+
+ /*
+ * File systems which do not implement ->writepage may use
+ * generic_file_readonly_mmap as their ->mmap op. If you call
+ * generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
+ * But we cannot call the lower ->mmap op, so we can't tell that
+ * writeable mappings won't work. Therefore, our only choice is to
+ * check if the lower file system supports the ->writepage, and if
+ * not, return EINVAL (the same error that
+ * generic_file_readonly_mmap returns in that case).
+ */
+ lower_file = unionfs_lower_file(file);
+ if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
+ err = -EINVAL;
+ printk(KERN_ERR "unionfs: branch %d file system does not "
+ "support writeable mmap\n", fbstart(file));
+ } else {
+ err = generic_file_mmap(file, vma);
+ if (err)
+ printk(KERN_ERR
+ "unionfs: generic_file_mmap failed %d\n", err);
+ }
+
+out:
+ if (!err) {
+ /* copyup could cause parent dir times to change */
+ unionfs_copy_attr_times(file->f_path.dentry->d_parent->d_inode);
+ unionfs_check_file(file);
+ unionfs_check_dentry(file->f_path.dentry->d_parent);
+ }
+ unionfs_read_unlock(file->f_path.dentry->d_sb);
+ return err;
+}
+
+int unionfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+ int bindex, bstart, bend;
+ struct file *lower_file;
+ struct dentry *lower_dentry;
+ struct inode *lower_inode, *inode;
+ int err = -EINVAL;
+
+ unionfs_read_lock(file->f_path.dentry->d_sb);
+ err = unionfs_file_revalidate(file, true);
+ if (unlikely(err))
+ goto out;
+ unionfs_check_file(file);
+
+ bstart = fbstart(file);
+ bend = fbend(file);
+ if (bstart < 0 || bend < 0)
+ goto out;
+
+ inode = dentry->d_inode;
+ if (unlikely(!inode)) {
+ printk(KERN_ERR
+ "unionfs: null lower inode in unionfs_fsync\n");
+ goto out;
+ }
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ lower_inode = unionfs_lower_inode_idx(inode, bindex);
+ if (!lower_inode || !lower_inode->i_fop->fsync)
+ continue;
+ lower_file = unionfs_lower_file_idx(file, bindex);
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ mutex_lock(&lower_inode->i_mutex);
+ err = lower_inode->i_fop->fsync(lower_file,
+ lower_dentry,
+ datasync);
+ mutex_unlock(&lower_inode->i_mutex);
+ if (err)
+ goto out;
+ }
+
+ unionfs_copy_attr_times(inode);
+
+out:
+ unionfs_check_file(file);
+ unionfs_read_unlock(file->f_path.dentry->d_sb);
+ return err;
+}
+
+int unionfs_fasync(int fd, struct file *file, int flag)
+{
+ int bindex, bstart, bend;
+ struct file *lower_file;
+ struct dentry *dentry;
+ struct inode *lower_inode, *inode;
+ int err = 0;
+
+ unionfs_read_lock(file->f_path.dentry->d_sb);
+ err = unionfs_file_revalidate(file, true);
+ if (unlikely(err))
+ goto out;
+ unionfs_check_file(file);
+
+ bstart = fbstart(file);
+ bend = fbend(file);
+ if (bstart < 0 || bend < 0)
+ goto out;
+
+ dentry = file->f_path.dentry;
+ inode = dentry->d_inode;
+ if (unlikely(!inode)) {
+ printk(KERN_ERR
+ "unionfs: null lower inode in unionfs_fasync\n");
+ goto out;
+ }
+ for (bindex = bstart; bindex <= bend; bindex++) {
+ lower_inode = unionfs_lower_inode_idx(inode, bindex);
+ if (!lower_inode || !lower_inode->i_fop->fasync)
+ continue;
+ lower_file = unionfs_lower_file_idx(file, bindex);
+ mutex_lock(&lower_inode->i_mutex);
+ err = lower_inode->i_fop->fasync(fd, lower_file, flag);
+ mutex_unlock(&lower_inode->i_mutex);
+ if (err)
+ goto out;
+ }
+
+ unionfs_copy_attr_times(inode);
+
+out:
+ unionfs_check_file(file);
+ unionfs_read_unlock(file->f_path.dentry->d_sb);
+ return err;
+}
+
+struct file_operations unionfs_main_fops = {
+ .llseek = generic_file_llseek,
+ .read = unionfs_read,
+ .aio_read = generic_file_aio_read,
+ .write = unionfs_write,
+ .aio_write = generic_file_aio_write,
+ .readdir = unionfs_file_readdir,
+ .unlocked_ioctl = unionfs_ioctl,
+ .mmap = unionfs_mmap,
+ .open = unionfs_open,
+ .flush = unionfs_flush,
+ .release = unionfs_file_release,
+ .fsync = unionfs_fsync,
+ .fasync = unionfs_fasync,
+ .splice_read = generic_file_splice_read,
+ .splice_write = generic_file_splice_write,
+};
--
1.5.2.2


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