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![Al Viro](/assets/img/avatar_default.png)
All places outside of core VFS that checked ->read and ->write for being NULL or called the methods directly are gone now, so NULL {read,write} with non-NULL {read,write}_iter will do the right thing in all cases. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
378 lines
8.6 KiB
C
378 lines
8.6 KiB
C
/* AFS filesystem file handling
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*
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* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/writeback.h>
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#include <linux/gfp.h>
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#include "internal.h"
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static int afs_readpage(struct file *file, struct page *page);
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static void afs_invalidatepage(struct page *page, unsigned int offset,
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unsigned int length);
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static int afs_releasepage(struct page *page, gfp_t gfp_flags);
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static int afs_launder_page(struct page *page);
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static int afs_readpages(struct file *filp, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages);
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const struct file_operations afs_file_operations = {
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.open = afs_open,
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.release = afs_release,
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.llseek = generic_file_llseek,
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.read_iter = generic_file_read_iter,
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.write_iter = afs_file_write,
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.mmap = generic_file_readonly_mmap,
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.splice_read = generic_file_splice_read,
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.fsync = afs_fsync,
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.lock = afs_lock,
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.flock = afs_flock,
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};
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const struct inode_operations afs_file_inode_operations = {
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.getattr = afs_getattr,
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.setattr = afs_setattr,
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.permission = afs_permission,
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};
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const struct address_space_operations afs_fs_aops = {
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.readpage = afs_readpage,
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.readpages = afs_readpages,
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.set_page_dirty = afs_set_page_dirty,
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.launder_page = afs_launder_page,
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.releasepage = afs_releasepage,
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.invalidatepage = afs_invalidatepage,
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.write_begin = afs_write_begin,
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.write_end = afs_write_end,
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.writepage = afs_writepage,
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.writepages = afs_writepages,
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};
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/*
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* open an AFS file or directory and attach a key to it
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*/
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int afs_open(struct inode *inode, struct file *file)
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{
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struct afs_vnode *vnode = AFS_FS_I(inode);
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struct key *key;
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int ret;
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_enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
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key = afs_request_key(vnode->volume->cell);
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if (IS_ERR(key)) {
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_leave(" = %ld [key]", PTR_ERR(key));
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return PTR_ERR(key);
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}
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ret = afs_validate(vnode, key);
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if (ret < 0) {
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_leave(" = %d [val]", ret);
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return ret;
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}
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file->private_data = key;
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_leave(" = 0");
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return 0;
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}
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/*
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* release an AFS file or directory and discard its key
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*/
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int afs_release(struct inode *inode, struct file *file)
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{
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struct afs_vnode *vnode = AFS_FS_I(inode);
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_enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
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key_put(file->private_data);
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_leave(" = 0");
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return 0;
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}
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#ifdef CONFIG_AFS_FSCACHE
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/*
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* deal with notification that a page was read from the cache
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*/
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static void afs_file_readpage_read_complete(struct page *page,
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void *data,
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int error)
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{
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_enter("%p,%p,%d", page, data, error);
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/* if the read completes with an error, we just unlock the page and let
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* the VM reissue the readpage */
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if (!error)
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SetPageUptodate(page);
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unlock_page(page);
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}
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#endif
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/*
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* read page from file, directory or symlink, given a key to use
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*/
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int afs_page_filler(void *data, struct page *page)
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{
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struct inode *inode = page->mapping->host;
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struct afs_vnode *vnode = AFS_FS_I(inode);
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struct key *key = data;
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size_t len;
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off_t offset;
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int ret;
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_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
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BUG_ON(!PageLocked(page));
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ret = -ESTALE;
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if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
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goto error;
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/* is it cached? */
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#ifdef CONFIG_AFS_FSCACHE
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ret = fscache_read_or_alloc_page(vnode->cache,
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page,
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afs_file_readpage_read_complete,
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NULL,
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GFP_KERNEL);
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#else
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ret = -ENOBUFS;
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#endif
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switch (ret) {
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/* read BIO submitted (page in cache) */
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case 0:
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break;
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/* page not yet cached */
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case -ENODATA:
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_debug("cache said ENODATA");
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goto go_on;
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/* page will not be cached */
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case -ENOBUFS:
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_debug("cache said ENOBUFS");
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default:
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go_on:
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offset = page->index << PAGE_CACHE_SHIFT;
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len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
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/* read the contents of the file from the server into the
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* page */
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ret = afs_vnode_fetch_data(vnode, key, offset, len, page);
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if (ret < 0) {
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if (ret == -ENOENT) {
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_debug("got NOENT from server"
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" - marking file deleted and stale");
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set_bit(AFS_VNODE_DELETED, &vnode->flags);
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ret = -ESTALE;
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}
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#ifdef CONFIG_AFS_FSCACHE
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fscache_uncache_page(vnode->cache, page);
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#endif
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BUG_ON(PageFsCache(page));
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goto error;
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}
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SetPageUptodate(page);
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/* send the page to the cache */
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#ifdef CONFIG_AFS_FSCACHE
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if (PageFsCache(page) &&
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fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
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fscache_uncache_page(vnode->cache, page);
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BUG_ON(PageFsCache(page));
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}
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#endif
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unlock_page(page);
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}
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_leave(" = 0");
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return 0;
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error:
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SetPageError(page);
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unlock_page(page);
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* read page from file, directory or symlink, given a file to nominate the key
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* to be used
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*/
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static int afs_readpage(struct file *file, struct page *page)
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{
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struct key *key;
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int ret;
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if (file) {
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key = file->private_data;
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ASSERT(key != NULL);
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ret = afs_page_filler(key, page);
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} else {
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struct inode *inode = page->mapping->host;
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key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
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if (IS_ERR(key)) {
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ret = PTR_ERR(key);
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} else {
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ret = afs_page_filler(key, page);
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key_put(key);
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}
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}
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return ret;
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}
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/*
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* read a set of pages
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*/
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static int afs_readpages(struct file *file, struct address_space *mapping,
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struct list_head *pages, unsigned nr_pages)
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{
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struct key *key = file->private_data;
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struct afs_vnode *vnode;
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int ret = 0;
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_enter("{%d},{%lu},,%d",
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key_serial(key), mapping->host->i_ino, nr_pages);
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ASSERT(key != NULL);
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vnode = AFS_FS_I(mapping->host);
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if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
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_leave(" = -ESTALE");
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return -ESTALE;
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}
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/* attempt to read as many of the pages as possible */
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#ifdef CONFIG_AFS_FSCACHE
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ret = fscache_read_or_alloc_pages(vnode->cache,
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mapping,
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pages,
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&nr_pages,
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afs_file_readpage_read_complete,
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NULL,
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mapping_gfp_mask(mapping));
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#else
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ret = -ENOBUFS;
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#endif
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switch (ret) {
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/* all pages are being read from the cache */
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case 0:
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BUG_ON(!list_empty(pages));
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BUG_ON(nr_pages != 0);
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_leave(" = 0 [reading all]");
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return 0;
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/* there were pages that couldn't be read from the cache */
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case -ENODATA:
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case -ENOBUFS:
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break;
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/* other error */
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default:
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_leave(" = %d", ret);
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return ret;
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}
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/* load the missing pages from the network */
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ret = read_cache_pages(mapping, pages, afs_page_filler, key);
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_leave(" = %d [netting]", ret);
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return ret;
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}
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/*
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* write back a dirty page
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*/
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static int afs_launder_page(struct page *page)
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{
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_enter("{%lu}", page->index);
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return 0;
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}
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/*
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* invalidate part or all of a page
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* - release a page and clean up its private data if offset is 0 (indicating
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* the entire page)
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*/
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static void afs_invalidatepage(struct page *page, unsigned int offset,
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unsigned int length)
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{
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struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
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_enter("{%lu},%u,%u", page->index, offset, length);
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BUG_ON(!PageLocked(page));
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/* we clean up only if the entire page is being invalidated */
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if (offset == 0 && length == PAGE_CACHE_SIZE) {
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#ifdef CONFIG_AFS_FSCACHE
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if (PageFsCache(page)) {
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struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
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fscache_wait_on_page_write(vnode->cache, page);
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fscache_uncache_page(vnode->cache, page);
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}
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#endif
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if (PagePrivate(page)) {
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if (wb && !PageWriteback(page)) {
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set_page_private(page, 0);
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afs_put_writeback(wb);
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}
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if (!page_private(page))
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ClearPagePrivate(page);
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}
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}
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_leave("");
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}
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/*
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* release a page and clean up its private state if it's not busy
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* - return true if the page can now be released, false if not
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*/
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static int afs_releasepage(struct page *page, gfp_t gfp_flags)
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{
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struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
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struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
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_enter("{{%x:%u}[%lu],%lx},%x",
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vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
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gfp_flags);
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/* deny if page is being written to the cache and the caller hasn't
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* elected to wait */
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#ifdef CONFIG_AFS_FSCACHE
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if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
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_leave(" = F [cache busy]");
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return 0;
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}
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#endif
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if (PagePrivate(page)) {
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if (wb) {
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set_page_private(page, 0);
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afs_put_writeback(wb);
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}
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ClearPagePrivate(page);
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}
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/* indicate that the page can be released */
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_leave(" = T");
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return 1;
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}
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