fs/afs/file.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* AFS filesystem file handling
  *
  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
 #include <linux/writeback.h>
 #include <linux/gfp.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/mm.h>
 #include "internal.h"

 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
 static int afs_readpage(struct file *file, struct page *page);
 static void afs_invalidatepage(struct page *page, unsigned int offset,
 			       unsigned int length);
 static int afs_releasepage(struct page *page, gfp_t gfp_flags);

 static int afs_readpages(struct file *filp, struct address_space *mapping,
 			 struct list_head *pages, unsigned nr_pages);

 const struct file_operations afs_file_operations = {
 	.open		= afs_open,
 	.release	= afs_release,
 	.llseek		= generic_file_llseek,
 	.read_iter	= generic_file_read_iter,
 	.write_iter	= afs_file_write,
 	.mmap		= afs_file_mmap,
 	.splice_read	= generic_file_splice_read,
 	.fsync		= afs_fsync,
 	.lock		= afs_lock,
 	.flock		= afs_flock,
 };

 const struct inode_operations afs_file_inode_operations = {
 	.getattr	= afs_getattr,
 	.setattr	= afs_setattr,
 	.permission	= afs_permission,
 	.listxattr	= afs_listxattr,
 };

 const struct address_space_operations afs_fs_aops = {
 	.readpage	= afs_readpage,
 	.readpages	= afs_readpages,
 	.set_page_dirty	= afs_set_page_dirty,
 	.launder_page	= afs_launder_page,
 	.releasepage	= afs_releasepage,
 	.invalidatepage	= afs_invalidatepage,
 	.write_begin	= afs_write_begin,
 	.write_end	= afs_write_end,
 	.writepage	= afs_writepage,
 	.writepages	= afs_writepages,
 };

 static const struct vm_operations_struct afs_vm_ops = {
 	.fault		= filemap_fault,
 	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= afs_page_mkwrite,
 };

 /*
  * Discard a pin on a writeback key.
  */
 void afs_put_wb_key(struct afs_wb_key *wbk)
 {
 	if (refcount_dec_and_test(&wbk->usage)) {
 		key_put(wbk->key);
 		kfree(wbk);
 	}
 }

 /*
  * Cache key for writeback.
  */
 int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
 {
 	struct afs_wb_key *wbk, *p;

 	wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
 	if (!wbk)
 		return -ENOMEM;
 	refcount_set(&wbk->usage, 2);
 	wbk->key = af->key;

 	spin_lock(&vnode->wb_lock);
 	list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
 		if (p->key == wbk->key)
 			goto found;
 	}

 	key_get(wbk->key);
 	list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
 	spin_unlock(&vnode->wb_lock);
 	af->wb = wbk;
 	return 0;

 found:
 	refcount_inc(&p->usage);
 	spin_unlock(&vnode->wb_lock);
 	af->wb = p;
 	kfree(wbk);
 	return 0;
 }

 /*
  * open an AFS file or directory and attach a key to it
  */
 int afs_open(struct inode *inode, struct file *file)
 {
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 	struct afs_file *af;
 	struct key *key;
 	int ret;

 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);

 	key = afs_request_key(vnode->volume->cell);
 	if (IS_ERR(key)) {
 		ret = PTR_ERR(key);
 		goto error;
 	}

 	af = kzalloc(sizeof(*af), GFP_KERNEL);
 	if (!af) {
 		ret = -ENOMEM;
 		goto error_key;
 	}
 	af->key = key;

 	ret = afs_validate(vnode, key);
 	if (ret < 0)
 		goto error_af;

 	if (file->f_mode & FMODE_WRITE) {
 		ret = afs_cache_wb_key(vnode, af);
 		if (ret < 0)
 			goto error_af;
 	}

 	if (file->f_flags & O_TRUNC)
 		set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);

 	file->private_data = af;
 	_leave(" = 0");
 	return 0;

 error_af:
 	kfree(af);
 error_key:
 	key_put(key);
 error:
 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * release an AFS file or directory and discard its key
  */
 int afs_release(struct inode *inode, struct file *file)
 {
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 	struct afs_file *af = file->private_data;
 	int ret = 0;

 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);

 	if ((file->f_mode & FMODE_WRITE))
 		ret = vfs_fsync(file, 0);

 	file->private_data = NULL;
 	if (af->wb)
 		afs_put_wb_key(af->wb);
 	key_put(af->key);
 	kfree(af);
 	afs_prune_wb_keys(vnode);
 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * Dispose of a ref to a read record.
  */
 void afs_put_read(struct afs_read *req)
 {
 	int i;

 	if (refcount_dec_and_test(&req->usage)) {
 		if (req->pages) {
 			for (i = 0; i < req->nr_pages; i++)
 				if (req->pages[i])
 					put_page(req->pages[i]);
 			if (req->pages != req->array)
 				kfree(req->pages);
 		}
 		kfree(req);
 	}
 }

 #ifdef CONFIG_AFS_FSCACHE
 /*
  * deal with notification that a page was read from the cache
  */
 static void afs_file_readpage_read_complete(struct page *page,
 					    void *data,
 					    int error)
 {
 	_enter("%p,%p,%d", page, data, error);

 	/* if the read completes with an error, we just unlock the page and let
 	 * the VM reissue the readpage */
 	if (!error)
 		SetPageUptodate(page);
 	unlock_page(page);
 }
 #endif

 /*
  * Fetch file data from the volume.
  */
 int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *req)
 {
 	struct afs_fs_cursor fc;
 	struct afs_status_cb *scb;
 	int ret;

 	_enter("%s{%llx:%llu.%u},%x,,,",
 	       vnode->volume->name,
 	       vnode->fid.vid,
 	       vnode->fid.vnode,
 	       vnode->fid.unique,
 	       key_serial(key));

 	scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
 	if (!scb)
 		return -ENOMEM;

 	ret = -ERESTARTSYS;
 	if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
 		afs_dataversion_t data_version = vnode->status.data_version;

 		while (afs_select_fileserver(&fc)) {
 			fc.cb_break = afs_calc_vnode_cb_break(vnode);
 			afs_fs_fetch_data(&fc, scb, req);
 		}

 		afs_check_for_remote_deletion(&fc, vnode);
 		afs_vnode_commit_status(&fc, vnode, fc.cb_break,
 					&data_version, scb);
 		ret = afs_end_vnode_operation(&fc);
 	}

 	if (ret == 0) {
 		afs_stat_v(vnode, n_fetches);
 		atomic_long_add(req->actual_len,
 				&afs_v2net(vnode)->n_fetch_bytes);
 	}

 	kfree(scb);
 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * read page from file, directory or symlink, given a key to use
  */
 int afs_page_filler(void *data, struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 	struct afs_read *req;
 	struct key *key = data;
 	int ret;

 	_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);

 	BUG_ON(!PageLocked(page));

 	ret = -ESTALE;
 	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 		goto error;

 	/* is it cached? */
 #ifdef CONFIG_AFS_FSCACHE
 	ret = fscache_read_or_alloc_page(vnode->cache,
 					 page,
 					 afs_file_readpage_read_complete,
 					 NULL,
 					 GFP_KERNEL);
 #else
 	ret = -ENOBUFS;
 #endif
 	switch (ret) {
 		/* read BIO submitted (page in cache) */
 	case 0:
 		break;

 		/* page not yet cached */
 	case -ENODATA:
 		_debug("cache said ENODATA");
 		goto go_on;

 		/* page will not be cached */
 	case -ENOBUFS:
 		_debug("cache said ENOBUFS");

 		/* fall through */
 	default:
 	go_on:
 		req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
 		if (!req)
 			goto enomem;

 		/* We request a full page.  If the page is a partial one at the
 		 * end of the file, the server will return a short read and the
 		 * unmarshalling code will clear the unfilled space.
 		 */
 		refcount_set(&req->usage, 1);
 		req->pos = (loff_t)page->index << PAGE_SHIFT;
 		req->len = PAGE_SIZE;
 		req->nr_pages = 1;
 		req->pages = req->array;
 		req->pages[0] = page;
 		get_page(page);

 		/* read the contents of the file from the server into the
 		 * page */
 		ret = afs_fetch_data(vnode, key, req);
 		afs_put_read(req);

 		if (ret < 0) {
 			if (ret == -ENOENT) {
 				_debug("got NOENT from server"
 				       " - marking file deleted and stale");
 				set_bit(AFS_VNODE_DELETED, &vnode->flags);
 				ret = -ESTALE;
 			}

 #ifdef CONFIG_AFS_FSCACHE
 			fscache_uncache_page(vnode->cache, page);
 #endif
 			BUG_ON(PageFsCache(page));

 			if (ret == -EINTR ||
 			    ret == -ENOMEM ||
 			    ret == -ERESTARTSYS ||
 			    ret == -EAGAIN)
 				goto error;
 			goto io_error;
 		}

 		SetPageUptodate(page);

 		/* send the page to the cache */
 #ifdef CONFIG_AFS_FSCACHE
 		if (PageFsCache(page) &&
 		    fscache_write_page(vnode->cache, page, vnode->status.size,
 				       GFP_KERNEL) != 0) {
 			fscache_uncache_page(vnode->cache, page);
 			BUG_ON(PageFsCache(page));
 		}
 #endif
 		unlock_page(page);
 	}

 	_leave(" = 0");
 	return 0;

 io_error:
 	SetPageError(page);
 	goto error;
 enomem:
 	ret = -ENOMEM;
 error:
 	unlock_page(page);
 	_leave(" = %d", ret);
 	return ret;
 }

 /*
  * read page from file, directory or symlink, given a file to nominate the key
  * to be used
  */
 static int afs_readpage(struct file *file, struct page *page)
 {
 	struct key *key;
 	int ret;

 	if (file) {
 		key = afs_file_key(file);
 		ASSERT(key != NULL);
 		ret = afs_page_filler(key, page);
 	} else {
 		struct inode *inode = page->mapping->host;
 		key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
 		if (IS_ERR(key)) {
 			ret = PTR_ERR(key);
 		} else {
 			ret = afs_page_filler(key, page);
 			key_put(key);
 		}
 	}
 	return ret;
 }

 /*
  * Make pages available as they're filled.
  */
 static void afs_readpages_page_done(struct afs_read *req)
 {
 #ifdef CONFIG_AFS_FSCACHE
 	struct afs_vnode *vnode = req->vnode;
 #endif
 	struct page *page = req->pages[req->index];

 	req->pages[req->index] = NULL;
 	SetPageUptodate(page);

 	/* send the page to the cache */
 #ifdef CONFIG_AFS_FSCACHE
 	if (PageFsCache(page) &&
 	    fscache_write_page(vnode->cache, page, vnode->status.size,
 			       GFP_KERNEL) != 0) {
 		fscache_uncache_page(vnode->cache, page);
 		BUG_ON(PageFsCache(page));
 	}
 #endif
 	unlock_page(page);
 	put_page(page);
 }

 /*
  * Read a contiguous set of pages.
  */
 static int afs_readpages_one(struct file *file, struct address_space *mapping,
 			     struct list_head *pages)
 {
 	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 	struct afs_read *req;
 	struct list_head *p;
 	struct page *first, *page;
 	struct key *key = afs_file_key(file);
 	pgoff_t index;
 	int ret, n, i;

 	/* Count the number of contiguous pages at the front of the list.  Note
 	 * that the list goes prev-wards rather than next-wards.
 	 */
 	first = lru_to_page(pages);
 	index = first->index + 1;
 	n = 1;
 	for (p = first->lru.prev; p != pages; p = p->prev) {
 		page = list_entry(p, struct page, lru);
 		if (page->index != index)
 			break;
 		index++;
 		n++;
 	}

 	req = kzalloc(struct_size(req, array, n), GFP_NOFS);
 	if (!req)
 		return -ENOMEM;

 	refcount_set(&req->usage, 1);
 	req->vnode = vnode;
 	req->page_done = afs_readpages_page_done;
 	req->pos = first->index;
 	req->pos <<= PAGE_SHIFT;
 	req->pages = req->array;

 	/* Transfer the pages to the request.  We add them in until one fails
 	 * to add to the LRU and then we stop (as that'll make a hole in the
 	 * contiguous run.
 	 *
 	 * Note that it's possible for the file size to change whilst we're
 	 * doing this, but we rely on the server returning less than we asked
 	 * for if the file shrank.  We also rely on this to deal with a partial
 	 * page at the end of the file.
 	 */
 	do {
 		page = lru_to_page(pages);
 		list_del(&page->lru);
 		index = page->index;
 		if (add_to_page_cache_lru(page, mapping, index,
 					  readahead_gfp_mask(mapping))) {
 #ifdef CONFIG_AFS_FSCACHE
 			fscache_uncache_page(vnode->cache, page);
 #endif
 			put_page(page);
 			break;
 		}

 		req->pages[req->nr_pages++] = page;
 		req->len += PAGE_SIZE;
 	} while (req->nr_pages < n);

 	if (req->nr_pages == 0) {
 		kfree(req);
 		return 0;
 	}

 	ret = afs_fetch_data(vnode, key, req);
 	if (ret < 0)
 		goto error;

 	task_io_account_read(PAGE_SIZE * req->nr_pages);
 	afs_put_read(req);
 	return 0;

 error:
 	if (ret == -ENOENT) {
 		_debug("got NOENT from server"
 		       " - marking file deleted and stale");
 		set_bit(AFS_VNODE_DELETED, &vnode->flags);
 		ret = -ESTALE;
 	}

 	for (i = 0; i < req->nr_pages; i++) {
 		page = req->pages[i];
 		if (page) {
 #ifdef CONFIG_AFS_FSCACHE
 			fscache_uncache_page(vnode->cache, page);
 #endif
 			SetPageError(page);
 			unlock_page(page);
 		}
 	}

 	afs_put_read(req);
 	return ret;
 }

 /*
  * read a set of pages
  */
 static int afs_readpages(struct file *file, struct address_space *mapping,
 			 struct list_head *pages, unsigned nr_pages)
 {
 	struct key *key = afs_file_key(file);
 	struct afs_vnode *vnode;
 	int ret = 0;

 	_enter("{%d},{%lu},,%d",
 	       key_serial(key), mapping->host->i_ino, nr_pages);

 	ASSERT(key != NULL);

 	vnode = AFS_FS_I(mapping->host);
 	if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
 		_leave(" = -ESTALE");
 		return -ESTALE;
 	}

 	/* attempt to read as many of the pages as possible */
 #ifdef CONFIG_AFS_FSCACHE
 	ret = fscache_read_or_alloc_pages(vnode->cache,
 					  mapping,
 					  pages,
 					  &nr_pages,
 					  afs_file_readpage_read_complete,
 					  NULL,
 					  mapping_gfp_mask(mapping));
 #else
 	ret = -ENOBUFS;
 #endif

 	switch (ret) {
 		/* all pages are being read from the cache */
 	case 0:
 		BUG_ON(!list_empty(pages));
 		BUG_ON(nr_pages != 0);
 		_leave(" = 0 [reading all]");
 		return 0;

 		/* there were pages that couldn't be read from the cache */
 	case -ENODATA:
 	case -ENOBUFS:
 		break;

 		/* other error */
 	default:
 		_leave(" = %d", ret);
 		return ret;
 	}

 	while (!list_empty(pages)) {
 		ret = afs_readpages_one(file, mapping, pages);
 		if (ret < 0)
 			break;
 	}

 	_leave(" = %d [netting]", ret);
 	return ret;
 }

 /*
  * invalidate part or all of a page
  * - release a page and clean up its private data if offset is 0 (indicating
  *   the entire page)
  */
 static void afs_invalidatepage(struct page *page, unsigned int offset,
 			       unsigned int length)
 {
 	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 	unsigned long priv;

 	_enter("{%lu},%u,%u", page->index, offset, length);

 	BUG_ON(!PageLocked(page));

 	/* we clean up only if the entire page is being invalidated */
 	if (offset == 0 && length == PAGE_SIZE) {
 #ifdef CONFIG_AFS_FSCACHE
 		if (PageFsCache(page)) {
 			struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 			fscache_wait_on_page_write(vnode->cache, page);
 			fscache_uncache_page(vnode->cache, page);
 		}
 #endif

 		if (PagePrivate(page)) {
 			priv = page_private(page);
 			trace_afs_page_dirty(vnode, tracepoint_string("inval"),
 					     page->index, priv);
 			set_page_private(page, 0);
 			ClearPagePrivate(page);
 		}
 	}

 	_leave("");
 }

 /*
  * release a page and clean up its private state if it's not busy
  * - return true if the page can now be released, false if not
  */
 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 {
 	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 	unsigned long priv;

 	_enter("{{%llx:%llu}[%lu],%lx},%x",
 	       vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 	       gfp_flags);

 	/* deny if page is being written to the cache and the caller hasn't
 	 * elected to wait */
 #ifdef CONFIG_AFS_FSCACHE
 	if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
 		_leave(" = F [cache busy]");
 		return 0;
 	}
 #endif

 	if (PagePrivate(page)) {
 		priv = page_private(page);
 		trace_afs_page_dirty(vnode, tracepoint_string("rel"),
 				     page->index, priv);
 		set_page_private(page, 0);
 		ClearPagePrivate(page);
 	}

 	/* indicate that the page can be released */
 	_leave(" = T");
 	return 1;
 }

 /*
  * Handle setting up a memory mapping on an AFS file.
  */
 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	int ret;

 	ret = generic_file_mmap(file, vma);
 	if (ret == 0)
 		vma->vm_ops = &afs_vm_ops;
 	return ret;
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* AFS filesystem file handling
	*
	* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/fs.h>
	#include <linux/pagemap.h>
	#include <linux/writeback.h>
	#include <linux/gfp.h>
	#include <linux/task_io_accounting_ops.h>
	#include <linux/mm.h>
	#include "internal.h"

	static int afs_file_mmap(struct file file, struct vm_area_struct vma);
	static int afs_readpage(struct file file, struct page page);
	static void afs_invalidatepage(struct page *page, unsigned int offset,
	unsigned int length);
	static int afs_releasepage(struct page *page, gfp_t gfp_flags);

	static int afs_readpages(struct file filp, struct address_space mapping,
	struct list_head *pages, unsigned nr_pages);

	const struct file_operations afs_file_operations = {
	.open = afs_open,
	.release = afs_release,
	.llseek = generic_file_llseek,
	.read_iter = generic_file_read_iter,
	.write_iter = afs_file_write,
	.mmap = afs_file_mmap,
	.splice_read = generic_file_splice_read,
	.fsync = afs_fsync,
	.lock = afs_lock,
	.flock = afs_flock,
	};

	const struct inode_operations afs_file_inode_operations = {
	.getattr = afs_getattr,
	.setattr = afs_setattr,
	.permission = afs_permission,
	.listxattr = afs_listxattr,
	};

	const struct address_space_operations afs_fs_aops = {
	.readpage = afs_readpage,
	.readpages = afs_readpages,
	.set_page_dirty = afs_set_page_dirty,
	.launder_page = afs_launder_page,
	.releasepage = afs_releasepage,
	.invalidatepage = afs_invalidatepage,
	.write_begin = afs_write_begin,
	.write_end = afs_write_end,
	.writepage = afs_writepage,
	.writepages = afs_writepages,
	};

	static const struct vm_operations_struct afs_vm_ops = {
	.fault = filemap_fault,
	.map_pages = filemap_map_pages,
	.page_mkwrite = afs_page_mkwrite,
	};

	/*
	* Discard a pin on a writeback key.
	*/
	void afs_put_wb_key(struct afs_wb_key *wbk)
	{
	if (refcount_dec_and_test(&wbk->usage)) {
	key_put(wbk->key);
	kfree(wbk);
	}
	}

	/*
	* Cache key for writeback.
	*/
	int afs_cache_wb_key(struct afs_vnode vnode, struct afs_file af)
	{
	struct afs_wb_key wbk, p;

	wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
	if (!wbk)
	return -ENOMEM;
	refcount_set(&wbk->usage, 2);
	wbk->key = af->key;

	spin_lock(&vnode->wb_lock);
	list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
	if (p->key == wbk->key)
	goto found;
	}

	key_get(wbk->key);
	list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
	spin_unlock(&vnode->wb_lock);
	af->wb = wbk;
	return 0;

	found:
	refcount_inc(&p->usage);
	spin_unlock(&vnode->wb_lock);
	af->wb = p;
	kfree(wbk);
	return 0;
	}

	/*
	* open an AFS file or directory and attach a key to it
	*/
	int afs_open(struct inode inode, struct file file)
	{
	struct afs_vnode *vnode = AFS_FS_I(inode);
	struct afs_file *af;
	struct key *key;
	int ret;

	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);

	key = afs_request_key(vnode->volume->cell);
	if (IS_ERR(key)) {
	ret = PTR_ERR(key);
	goto error;
	}

	af = kzalloc(sizeof(*af), GFP_KERNEL);
	if (!af) {
	ret = -ENOMEM;
	goto error_key;
	}
	af->key = key;

	ret = afs_validate(vnode, key);
	if (ret < 0)
	goto error_af;

	if (file->f_mode & FMODE_WRITE) {
	ret = afs_cache_wb_key(vnode, af);
	if (ret < 0)
	goto error_af;
	}

	if (file->f_flags & O_TRUNC)
	set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);

	file->private_data = af;
	_leave(" = 0");
	return 0;

	error_af:
	kfree(af);
	error_key:
	key_put(key);
	error:
	_leave(" = %d", ret);
	return ret;
	}

	/*
	* release an AFS file or directory and discard its key
	*/
	int afs_release(struct inode inode, struct file file)
	{
	struct afs_vnode *vnode = AFS_FS_I(inode);
	struct afs_file *af = file->private_data;
	int ret = 0;

	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);

	if ((file->f_mode & FMODE_WRITE))
	ret = vfs_fsync(file, 0);

	file->private_data = NULL;
	if (af->wb)
	afs_put_wb_key(af->wb);
	key_put(af->key);
	kfree(af);
	afs_prune_wb_keys(vnode);
	_leave(" = %d", ret);
	return ret;
	}

	/*
	* Dispose of a ref to a read record.
	*/
	void afs_put_read(struct afs_read *req)
	{
	int i;

	if (refcount_dec_and_test(&req->usage)) {
	if (req->pages) {
	for (i = 0; i < req->nr_pages; i++)
	if (req->pages[i])
	put_page(req->pages[i]);
	if (req->pages != req->array)
	kfree(req->pages);
	}
	kfree(req);
	}
	}

	#ifdef CONFIG_AFS_FSCACHE
	/*
	* deal with notification that a page was read from the cache
	*/
	static void afs_file_readpage_read_complete(struct page *page,
	void *data,
	int error)
	{
	_enter("%p,%p,%d", page, data, error);

	/* if the read completes with an error, we just unlock the page and let
	* the VM reissue the readpage */
	if (!error)
	SetPageUptodate(page);
	unlock_page(page);
	}
	#endif

	/*
	* Fetch file data from the volume.
	*/
	int afs_fetch_data(struct afs_vnode vnode, struct key key, struct afs_read *req)
	{
	struct afs_fs_cursor fc;
	struct afs_status_cb *scb;
	int ret;

	_enter("%s{%llx:%llu.%u},%x,,,",
	vnode->volume->name,
	vnode->fid.vid,
	vnode->fid.vnode,
	vnode->fid.unique,
	key_serial(key));

	scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
	if (!scb)
	return -ENOMEM;

	ret = -ERESTARTSYS;
	if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
	afs_dataversion_t data_version = vnode->status.data_version;

	while (afs_select_fileserver(&fc)) {
	fc.cb_break = afs_calc_vnode_cb_break(vnode);
	afs_fs_fetch_data(&fc, scb, req);
	}

	afs_check_for_remote_deletion(&fc, vnode);
	afs_vnode_commit_status(&fc, vnode, fc.cb_break,
	&data_version, scb);
	ret = afs_end_vnode_operation(&fc);
	}

	if (ret == 0) {
	afs_stat_v(vnode, n_fetches);
	atomic_long_add(req->actual_len,
	&afs_v2net(vnode)->n_fetch_bytes);
	}

	kfree(scb);
	_leave(" = %d", ret);
	return ret;
	}

	/*
	* read page from file, directory or symlink, given a key to use
	*/
	int afs_page_filler(void data, struct page page)
	{
	struct inode *inode = page->mapping->host;
	struct afs_vnode *vnode = AFS_FS_I(inode);
	struct afs_read *req;
	struct key *key = data;
	int ret;

	_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);

	BUG_ON(!PageLocked(page));

	ret = -ESTALE;
	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
	goto error;

	/* is it cached? */
	#ifdef CONFIG_AFS_FSCACHE
	ret = fscache_read_or_alloc_page(vnode->cache,
	page,
	afs_file_readpage_read_complete,
	NULL,
	GFP_KERNEL);
	#else
	ret = -ENOBUFS;
	#endif
	switch (ret) {
	/* read BIO submitted (page in cache) */
	case 0:
	break;

	/* page not yet cached */
	case -ENODATA:
	_debug("cache said ENODATA");
	goto go_on;

	/* page will not be cached */
	case -ENOBUFS:
	_debug("cache said ENOBUFS");

	/* fall through */
	default:
	go_on:
	req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
	if (!req)
	goto enomem;

	/* We request a full page. If the page is a partial one at the
	* end of the file, the server will return a short read and the
	* unmarshalling code will clear the unfilled space.
	*/
	refcount_set(&req->usage, 1);
	req->pos = (loff_t)page->index << PAGE_SHIFT;
	req->len = PAGE_SIZE;
	req->nr_pages = 1;
	req->pages = req->array;
	req->pages[0] = page;
	get_page(page);

	/* read the contents of the file from the server into the
	* page */
	ret = afs_fetch_data(vnode, key, req);
	afs_put_read(req);

	if (ret < 0) {
	if (ret == -ENOENT) {
	_debug("got NOENT from server"
	" - marking file deleted and stale");
	set_bit(AFS_VNODE_DELETED, &vnode->flags);
	ret = -ESTALE;
	}

	#ifdef CONFIG_AFS_FSCACHE
	fscache_uncache_page(vnode->cache, page);
	#endif
	BUG_ON(PageFsCache(page));

	if (ret == -EINTR \|\|
	ret == -ENOMEM \|\|
	ret == -ERESTARTSYS \|\|
	ret == -EAGAIN)
	goto error;
	goto io_error;
	}

	SetPageUptodate(page);

	/* send the page to the cache */
	#ifdef CONFIG_AFS_FSCACHE
	if (PageFsCache(page) &&
	fscache_write_page(vnode->cache, page, vnode->status.size,
	GFP_KERNEL) != 0) {
	fscache_uncache_page(vnode->cache, page);
	BUG_ON(PageFsCache(page));
	}
	#endif
	unlock_page(page);
	}

	_leave(" = 0");
	return 0;

	io_error:
	SetPageError(page);
	goto error;
	enomem:
	ret = -ENOMEM;
	error:
	unlock_page(page);
	_leave(" = %d", ret);
	return ret;
	}

	/*
	* read page from file, directory or symlink, given a file to nominate the key
	* to be used
	*/
	static int afs_readpage(struct file file, struct page page)
	{
	struct key *key;
	int ret;

	if (file) {
	key = afs_file_key(file);
	ASSERT(key != NULL);
	ret = afs_page_filler(key, page);
	} else {
	struct inode *inode = page->mapping->host;
	key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
	if (IS_ERR(key)) {
	ret = PTR_ERR(key);
	} else {
	ret = afs_page_filler(key, page);
	key_put(key);
	}
	}
	return ret;
	}

	/*
	* Make pages available as they're filled.
	*/
	static void afs_readpages_page_done(struct afs_read *req)
	{
	#ifdef CONFIG_AFS_FSCACHE
	struct afs_vnode *vnode = req->vnode;
	#endif
	struct page *page = req->pages[req->index];

	req->pages[req->index] = NULL;
	SetPageUptodate(page);

	/* send the page to the cache */
	#ifdef CONFIG_AFS_FSCACHE
	if (PageFsCache(page) &&
	fscache_write_page(vnode->cache, page, vnode->status.size,
	GFP_KERNEL) != 0) {
	fscache_uncache_page(vnode->cache, page);
	BUG_ON(PageFsCache(page));
	}
	#endif
	unlock_page(page);
	put_page(page);
	}

	/*
	* Read a contiguous set of pages.
	*/
	static int afs_readpages_one(struct file file, struct address_space mapping,
	struct list_head *pages)
	{
	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
	struct afs_read *req;
	struct list_head *p;
	struct page first, page;
	struct key *key = afs_file_key(file);
	pgoff_t index;
	int ret, n, i;

	/* Count the number of contiguous pages at the front of the list. Note
	* that the list goes prev-wards rather than next-wards.
	*/
	first = lru_to_page(pages);
	index = first->index + 1;
	n = 1;
	for (p = first->lru.prev; p != pages; p = p->prev) {
	page = list_entry(p, struct page, lru);
	if (page->index != index)
	break;
	index++;
	n++;
	}

	req = kzalloc(struct_size(req, array, n), GFP_NOFS);
	if (!req)
	return -ENOMEM;

	refcount_set(&req->usage, 1);
	req->vnode = vnode;
	req->page_done = afs_readpages_page_done;
	req->pos = first->index;
	req->pos <<= PAGE_SHIFT;
	req->pages = req->array;

	/* Transfer the pages to the request. We add them in until one fails
	* to add to the LRU and then we stop (as that'll make a hole in the
	* contiguous run.
	*
	* Note that it's possible for the file size to change whilst we're
	* doing this, but we rely on the server returning less than we asked
	* for if the file shrank. We also rely on this to deal with a partial
	* page at the end of the file.
	*/
	do {
	page = lru_to_page(pages);
	list_del(&page->lru);
	index = page->index;
	if (add_to_page_cache_lru(page, mapping, index,
	readahead_gfp_mask(mapping))) {
	#ifdef CONFIG_AFS_FSCACHE
	fscache_uncache_page(vnode->cache, page);
	#endif
	put_page(page);
	break;
	}

	req->pages[req->nr_pages++] = page;
	req->len += PAGE_SIZE;
	} while (req->nr_pages < n);

	if (req->nr_pages == 0) {
	kfree(req);
	return 0;
	}

	ret = afs_fetch_data(vnode, key, req);
	if (ret < 0)
	goto error;

	task_io_account_read(PAGE_SIZE * req->nr_pages);
	afs_put_read(req);
	return 0;

	error:
	if (ret == -ENOENT) {
	_debug("got NOENT from server"
	" - marking file deleted and stale");
	set_bit(AFS_VNODE_DELETED, &vnode->flags);
	ret = -ESTALE;
	}

	for (i = 0; i < req->nr_pages; i++) {
	page = req->pages[i];
	if (page) {
	#ifdef CONFIG_AFS_FSCACHE
	fscache_uncache_page(vnode->cache, page);
	#endif
	SetPageError(page);
	unlock_page(page);
	}
	}

	afs_put_read(req);
	return ret;
	}

	/*
	* read a set of pages
	*/
	static int afs_readpages(struct file file, struct address_space mapping,
	struct list_head *pages, unsigned nr_pages)
	{
	struct key *key = afs_file_key(file);
	struct afs_vnode *vnode;
	int ret = 0;

	_enter("{%d},{%lu},,%d",
	key_serial(key), mapping->host->i_ino, nr_pages);

	ASSERT(key != NULL);

	vnode = AFS_FS_I(mapping->host);
	if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
	_leave(" = -ESTALE");
	return -ESTALE;
	}

	/* attempt to read as many of the pages as possible */
	#ifdef CONFIG_AFS_FSCACHE
	ret = fscache_read_or_alloc_pages(vnode->cache,
	mapping,
	pages,
	&nr_pages,
	afs_file_readpage_read_complete,
	NULL,
	mapping_gfp_mask(mapping));
	#else
	ret = -ENOBUFS;
	#endif

	switch (ret) {
	/* all pages are being read from the cache */
	case 0:
	BUG_ON(!list_empty(pages));
	BUG_ON(nr_pages != 0);
	_leave(" = 0 [reading all]");
	return 0;

	/* there were pages that couldn't be read from the cache */
	case -ENODATA:
	case -ENOBUFS:
	break;

	/* other error */
	default:
	_leave(" = %d", ret);
	return ret;
	}

	while (!list_empty(pages)) {
	ret = afs_readpages_one(file, mapping, pages);
	if (ret < 0)
	break;
	}

	_leave(" = %d [netting]", ret);
	return ret;
	}

	/*
	* invalidate part or all of a page
	* - release a page and clean up its private data if offset is 0 (indicating
	* the entire page)
	*/
	static void afs_invalidatepage(struct page *page, unsigned int offset,
	unsigned int length)
	{
	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
	unsigned long priv;

	_enter("{%lu},%u,%u", page->index, offset, length);

	BUG_ON(!PageLocked(page));

	/* we clean up only if the entire page is being invalidated */
	if (offset == 0 && length == PAGE_SIZE) {
	#ifdef CONFIG_AFS_FSCACHE
	if (PageFsCache(page)) {
	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
	fscache_wait_on_page_write(vnode->cache, page);
	fscache_uncache_page(vnode->cache, page);
	}
	#endif

	if (PagePrivate(page)) {
	priv = page_private(page);
	trace_afs_page_dirty(vnode, tracepoint_string("inval"),
	page->index, priv);
	set_page_private(page, 0);
	ClearPagePrivate(page);
	}
	}

	_leave("");
	}

	/*
	* release a page and clean up its private state if it's not busy
	* - return true if the page can now be released, false if not
	*/
	static int afs_releasepage(struct page *page, gfp_t gfp_flags)
	{
	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
	unsigned long priv;

	_enter("{{%llx:%llu}[%lu],%lx},%x",
	vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
	gfp_flags);

	/* deny if page is being written to the cache and the caller hasn't
	* elected to wait */
	#ifdef CONFIG_AFS_FSCACHE
	if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
	_leave(" = F [cache busy]");
	return 0;
	}
	#endif

	if (PagePrivate(page)) {
	priv = page_private(page);
	trace_afs_page_dirty(vnode, tracepoint_string("rel"),
	page->index, priv);
	set_page_private(page, 0);
	ClearPagePrivate(page);
	}

	/* indicate that the page can be released */
	_leave(" = T");
	return 1;
	}

	/*
	* Handle setting up a memory mapping on an AFS file.
	*/
	static int afs_file_mmap(struct file file, struct vm_area_struct vma)
	{
	int ret;

	ret = generic_file_mmap(file, vma);
	if (ret == 0)
	vma->vm_ops = &afs_vm_ops;
	return ret;
	}