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![Jan Harkes](/assets/img/avatar_default.png)
This is an variation on the patch sent by Christoph Hellwig which kills file_count abuse by the Coda kernel module by moving the coda_flush functionality into coda_release. However part of reason we were using the coda_flush callback was to allow Coda to pass errors that occur during writeback from the userspace cache manager back to close(). As Al Viro explained on linux-fsdevel, it is impossible to guarantee that such errors can in fact be returned back to the caller. There are many cases where the last reference to a file is not released by the close system call and it is also impossible to pick some close as a 'last-close' and delay it until all other references have been destroyed. The CODA_STORE/CODA_RELEASE upcall combination is clearly a broken design, and it is better to remove it completely. Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@ftp.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
243 lines
6.2 KiB
C
243 lines
6.2 KiB
C
/*
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* File operations for Coda.
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* Original version: (C) 1996 Peter Braam
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* Rewritten for Linux 2.1: (C) 1997 Carnegie Mellon University
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*
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* Carnegie Mellon encourages users of this code to contribute improvements
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* to the Coda project. Contact Peter Braam <coda@cs.cmu.edu>.
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/time.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/stat.h>
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#include <linux/errno.h>
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#include <linux/smp_lock.h>
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#include <linux/string.h>
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#include <asm/uaccess.h>
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#include <linux/coda.h>
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#include <linux/coda_linux.h>
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#include <linux/coda_fs_i.h>
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#include <linux/coda_psdev.h>
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#include "coda_int.h"
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static ssize_t
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coda_file_read(struct file *coda_file, char __user *buf, size_t count, loff_t *ppos)
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{
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struct coda_file_info *cfi;
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struct file *host_file;
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cfi = CODA_FTOC(coda_file);
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BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
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host_file = cfi->cfi_container;
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if (!host_file->f_op || !host_file->f_op->read)
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return -EINVAL;
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return host_file->f_op->read(host_file, buf, count, ppos);
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}
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static ssize_t
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coda_file_splice_read(struct file *coda_file, loff_t *ppos,
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struct pipe_inode_info *pipe, size_t count,
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unsigned int flags)
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{
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struct coda_file_info *cfi;
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struct file *host_file;
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cfi = CODA_FTOC(coda_file);
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BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
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host_file = cfi->cfi_container;
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if (!host_file->f_op || !host_file->f_op->splice_read)
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return -EINVAL;
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return host_file->f_op->splice_read(host_file, ppos, pipe, count,flags);
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}
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static ssize_t
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coda_file_write(struct file *coda_file, const char __user *buf, size_t count, loff_t *ppos)
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{
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struct inode *host_inode, *coda_inode = coda_file->f_path.dentry->d_inode;
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struct coda_file_info *cfi;
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struct file *host_file;
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ssize_t ret;
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cfi = CODA_FTOC(coda_file);
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BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
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host_file = cfi->cfi_container;
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if (!host_file->f_op || !host_file->f_op->write)
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return -EINVAL;
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host_inode = host_file->f_path.dentry->d_inode;
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mutex_lock(&coda_inode->i_mutex);
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ret = host_file->f_op->write(host_file, buf, count, ppos);
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coda_inode->i_size = host_inode->i_size;
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coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
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coda_inode->i_mtime = coda_inode->i_ctime = CURRENT_TIME_SEC;
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mutex_unlock(&coda_inode->i_mutex);
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return ret;
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}
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static int
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coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma)
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{
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struct coda_file_info *cfi;
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struct coda_inode_info *cii;
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struct file *host_file;
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struct inode *coda_inode, *host_inode;
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cfi = CODA_FTOC(coda_file);
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BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
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host_file = cfi->cfi_container;
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if (!host_file->f_op || !host_file->f_op->mmap)
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return -ENODEV;
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coda_inode = coda_file->f_path.dentry->d_inode;
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host_inode = host_file->f_path.dentry->d_inode;
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coda_file->f_mapping = host_file->f_mapping;
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if (coda_inode->i_mapping == &coda_inode->i_data)
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coda_inode->i_mapping = host_inode->i_mapping;
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/* only allow additional mmaps as long as userspace isn't changing
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* the container file on us! */
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else if (coda_inode->i_mapping != host_inode->i_mapping)
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return -EBUSY;
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/* keep track of how often the coda_inode/host_file has been mmapped */
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cii = ITOC(coda_inode);
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cii->c_mapcount++;
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cfi->cfi_mapcount++;
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return host_file->f_op->mmap(host_file, vma);
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}
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int coda_open(struct inode *coda_inode, struct file *coda_file)
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{
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struct file *host_file = NULL;
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int error;
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unsigned short flags = coda_file->f_flags & (~O_EXCL);
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unsigned short coda_flags = coda_flags_to_cflags(flags);
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struct coda_file_info *cfi;
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cfi = kmalloc(sizeof(struct coda_file_info), GFP_KERNEL);
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if (!cfi)
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return -ENOMEM;
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lock_kernel();
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error = venus_open(coda_inode->i_sb, coda_i2f(coda_inode), coda_flags,
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&host_file);
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if (!host_file)
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error = -EIO;
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if (error) {
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kfree(cfi);
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unlock_kernel();
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return error;
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}
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host_file->f_flags |= coda_file->f_flags & (O_APPEND | O_SYNC);
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cfi->cfi_magic = CODA_MAGIC;
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cfi->cfi_mapcount = 0;
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cfi->cfi_container = host_file;
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BUG_ON(coda_file->private_data != NULL);
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coda_file->private_data = cfi;
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unlock_kernel();
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return 0;
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}
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int coda_release(struct inode *coda_inode, struct file *coda_file)
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{
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unsigned short flags = (coda_file->f_flags) & (~O_EXCL);
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unsigned short coda_flags = coda_flags_to_cflags(flags);
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struct coda_file_info *cfi;
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struct coda_inode_info *cii;
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struct inode *host_inode;
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int err = 0;
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lock_kernel();
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cfi = CODA_FTOC(coda_file);
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BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
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err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
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coda_flags, coda_file->f_uid);
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host_inode = cfi->cfi_container->f_path.dentry->d_inode;
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cii = ITOC(coda_inode);
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/* did we mmap this file? */
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if (coda_inode->i_mapping == &host_inode->i_data) {
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cii->c_mapcount -= cfi->cfi_mapcount;
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if (!cii->c_mapcount)
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coda_inode->i_mapping = &coda_inode->i_data;
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}
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fput(cfi->cfi_container);
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kfree(coda_file->private_data);
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coda_file->private_data = NULL;
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unlock_kernel();
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/* VFS fput ignores the return value from file_operations->release, so
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* there is no use returning an error here */
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return 0;
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}
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int coda_fsync(struct file *coda_file, struct dentry *coda_dentry, int datasync)
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{
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struct file *host_file;
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struct dentry *host_dentry;
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struct inode *host_inode, *coda_inode = coda_dentry->d_inode;
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struct coda_file_info *cfi;
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int err = 0;
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if (!(S_ISREG(coda_inode->i_mode) || S_ISDIR(coda_inode->i_mode) ||
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S_ISLNK(coda_inode->i_mode)))
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return -EINVAL;
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cfi = CODA_FTOC(coda_file);
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BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
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host_file = cfi->cfi_container;
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if (host_file->f_op && host_file->f_op->fsync) {
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host_dentry = host_file->f_path.dentry;
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host_inode = host_dentry->d_inode;
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mutex_lock(&host_inode->i_mutex);
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err = host_file->f_op->fsync(host_file, host_dentry, datasync);
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mutex_unlock(&host_inode->i_mutex);
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}
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if ( !err && !datasync ) {
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lock_kernel();
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err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
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unlock_kernel();
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}
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return err;
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}
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const struct file_operations coda_file_operations = {
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.llseek = generic_file_llseek,
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.read = coda_file_read,
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.write = coda_file_write,
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.mmap = coda_file_mmap,
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.open = coda_open,
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.release = coda_release,
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.fsync = coda_fsync,
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.splice_read = coda_file_splice_read,
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};
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