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![Pedro Cuadra](/assets/img/avatar_default.png)
This adds support for partial file caching in Coda. Every read, write and mmap informs the userspace cache manager about what part of a file is about to be accessed so that the cache manager can ensure the relevant parts are available before the operation is allowed to proceed. When a read or write operation completes, this is also reported to allow the cache manager to track when partially cached content can be released. If the cache manager does not support partial file caching, or when the entire file has been fetched into the local cache, the cache manager may return an EOPNOTSUPP error to indicate that intent upcalls are no longer necessary until the file is closed. [akpm@linux-foundation.org: little whitespace fixup] Link: http://lkml.kernel.org/r/20190618181301.6960-1-jaharkes@cs.cmu.edu Signed-off-by: Pedro Cuadra <pjcuadra@gmail.com> Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
305 lines
7.9 KiB
C
305 lines
7.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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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/cred.h>
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#include <linux/errno.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/uio.h>
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#include <linux/coda.h>
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#include "coda_psdev.h"
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#include "coda_linux.h"
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#include "coda_int.h"
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struct coda_vm_ops {
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atomic_t refcnt;
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struct file *coda_file;
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const struct vm_operations_struct *host_vm_ops;
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struct vm_operations_struct vm_ops;
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};
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static ssize_t
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coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
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{
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struct file *coda_file = iocb->ki_filp;
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struct inode *coda_inode = file_inode(coda_file);
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struct coda_file_info *cfi = coda_ftoc(coda_file);
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loff_t ki_pos = iocb->ki_pos;
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size_t count = iov_iter_count(to);
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ssize_t ret;
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ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
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&cfi->cfi_access_intent,
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count, ki_pos, CODA_ACCESS_TYPE_READ);
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if (ret)
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goto finish_read;
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ret = vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);
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finish_read:
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venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
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&cfi->cfi_access_intent,
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count, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
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return ret;
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}
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static ssize_t
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coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
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{
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struct file *coda_file = iocb->ki_filp;
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struct inode *coda_inode = file_inode(coda_file);
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struct coda_file_info *cfi = coda_ftoc(coda_file);
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struct file *host_file = cfi->cfi_container;
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loff_t ki_pos = iocb->ki_pos;
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size_t count = iov_iter_count(to);
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ssize_t ret;
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ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
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&cfi->cfi_access_intent,
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count, ki_pos, CODA_ACCESS_TYPE_WRITE);
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if (ret)
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goto finish_write;
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file_start_write(host_file);
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inode_lock(coda_inode);
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ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos, 0);
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coda_inode->i_size = file_inode(host_file)->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(coda_inode);
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inode_unlock(coda_inode);
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file_end_write(host_file);
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finish_write:
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venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
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&cfi->cfi_access_intent,
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count, ki_pos, CODA_ACCESS_TYPE_WRITE_FINISH);
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return ret;
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}
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static void
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coda_vm_open(struct vm_area_struct *vma)
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{
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struct coda_vm_ops *cvm_ops =
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container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
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atomic_inc(&cvm_ops->refcnt);
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if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->open)
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cvm_ops->host_vm_ops->open(vma);
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}
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static void
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coda_vm_close(struct vm_area_struct *vma)
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{
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struct coda_vm_ops *cvm_ops =
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container_of(vma->vm_ops, struct coda_vm_ops, vm_ops);
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if (cvm_ops->host_vm_ops && cvm_ops->host_vm_ops->close)
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cvm_ops->host_vm_ops->close(vma);
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if (atomic_dec_and_test(&cvm_ops->refcnt)) {
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vma->vm_ops = cvm_ops->host_vm_ops;
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fput(cvm_ops->coda_file);
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kfree(cvm_ops);
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}
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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 inode *coda_inode = file_inode(coda_file);
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struct coda_file_info *cfi = coda_ftoc(coda_file);
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struct file *host_file = cfi->cfi_container;
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struct inode *host_inode = file_inode(host_file);
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struct coda_inode_info *cii;
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struct coda_vm_ops *cvm_ops;
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loff_t ppos;
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size_t count;
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int ret;
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if (!host_file->f_op->mmap)
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return -ENODEV;
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if (WARN_ON(coda_file != vma->vm_file))
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return -EIO;
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count = vma->vm_end - vma->vm_start;
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ppos = vma->vm_pgoff * PAGE_SIZE;
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ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
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&cfi->cfi_access_intent,
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count, ppos, CODA_ACCESS_TYPE_MMAP);
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if (ret)
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return ret;
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cvm_ops = kmalloc(sizeof(struct coda_vm_ops), GFP_KERNEL);
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if (!cvm_ops)
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return -ENOMEM;
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cii = ITOC(coda_inode);
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spin_lock(&cii->c_lock);
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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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spin_unlock(&cii->c_lock);
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kfree(cvm_ops);
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return -EBUSY;
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}
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/* keep track of how often the coda_inode/host_file has been mmapped */
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cii->c_mapcount++;
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cfi->cfi_mapcount++;
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spin_unlock(&cii->c_lock);
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vma->vm_file = get_file(host_file);
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ret = call_mmap(vma->vm_file, vma);
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if (ret) {
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/* if call_mmap fails, our caller will put coda_file so we
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* should drop the reference to the host_file that we got.
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*/
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fput(host_file);
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kfree(cvm_ops);
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} else {
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/* here we add redirects for the open/close vm_operations */
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cvm_ops->host_vm_ops = vma->vm_ops;
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if (vma->vm_ops)
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cvm_ops->vm_ops = *vma->vm_ops;
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cvm_ops->vm_ops.open = coda_vm_open;
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cvm_ops->vm_ops.close = coda_vm_close;
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cvm_ops->coda_file = coda_file;
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atomic_set(&cvm_ops->refcnt, 1);
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vma->vm_ops = &cvm_ops->vm_ops;
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}
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return ret;
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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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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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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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/* assume access intents are supported unless we hear otherwise */
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cfi->cfi_access_intent = true;
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BUG_ON(coda_file->private_data != NULL);
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coda_file->private_data = cfi;
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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;
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cfi = coda_ftoc(coda_file);
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err = venus_close(coda_inode->i_sb, coda_i2f(coda_inode),
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coda_flags, coda_file->f_cred->fsuid);
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host_inode = file_inode(cfi->cfi_container);
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cii = ITOC(coda_inode);
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/* did we mmap this file? */
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spin_lock(&cii->c_lock);
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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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spin_unlock(&cii->c_lock);
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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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/* 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, loff_t start, loff_t end, int datasync)
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{
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struct file *host_file;
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struct inode *coda_inode = file_inode(coda_file);
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struct coda_file_info *cfi;
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int err;
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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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err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
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if (err)
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return err;
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inode_lock(coda_inode);
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cfi = coda_ftoc(coda_file);
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host_file = cfi->cfi_container;
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err = vfs_fsync(host_file, datasync);
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if (!err && !datasync)
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err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
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inode_unlock(coda_inode);
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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_iter = coda_file_read_iter,
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.write_iter = coda_file_write_iter,
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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 = generic_file_splice_read,
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};
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