fs/fscache/io.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* Cache data I/O routines
  *
  * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */
 #define FSCACHE_DEBUG_LEVEL OPERATION
 #include <linux/fscache-cache.h>
 #include <linux/uio.h>
 #include <linux/bvec.h>
 #include <linux/slab.h>
 #include <linux/uio.h>
 #include "internal.h"

 /**
  * fscache_wait_for_operation - Wait for an object become accessible
  * @cres: The cache resources for the operation being performed
  * @want_state: The minimum state the object must be at
  *
  * See if the target cache object is at the specified minimum state of
  * accessibility yet, and if not, wait for it.
  */
 bool fscache_wait_for_operation(struct netfs_cache_resources *cres,
 				enum fscache_want_state want_state)
 {
 	struct fscache_cookie *cookie = fscache_cres_cookie(cres);
 	enum fscache_cookie_state state;

 again:
 	if (!fscache_cache_is_live(cookie->volume->cache)) {
 		_leave(" [broken]");
 		return false;
 	}

 	state = fscache_cookie_state(cookie);
 	_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);

 	switch (state) {
 	case FSCACHE_COOKIE_STATE_CREATING:
 	case FSCACHE_COOKIE_STATE_INVALIDATING:
 		if (want_state == FSCACHE_WANT_PARAMS)
 			goto ready; /* There can be no content */
 		fallthrough;
 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
 	case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
 		wait_var_event(&cookie->state,
 			       fscache_cookie_state(cookie) != state);
 		goto again;

 	case FSCACHE_COOKIE_STATE_ACTIVE:
 		goto ready;
 	case FSCACHE_COOKIE_STATE_DROPPED:
 	case FSCACHE_COOKIE_STATE_RELINQUISHING:
 	default:
 		_leave(" [not live]");
 		return false;
 	}

 ready:
 	if (!cres->cache_priv2)
 		return cookie->volume->cache->ops->begin_operation(cres, want_state);
 	return true;
 }
 EXPORT_SYMBOL(fscache_wait_for_operation);

 /*
  * Begin an I/O operation on the cache, waiting till we reach the right state.
  *
  * Attaches the resources required to the operation resources record.
  */
 static int fscache_begin_operation(struct netfs_cache_resources *cres,
 				   struct fscache_cookie *cookie,
 				   enum fscache_want_state want_state,
 				   enum fscache_access_trace why)
 {
 	enum fscache_cookie_state state;
 	long timeo;
 	bool once_only = false;

 	cres->ops		= NULL;
 	cres->cache_priv	= cookie;
 	cres->cache_priv2	= NULL;
 	cres->debug_id		= cookie->debug_id;
 	cres->inval_counter	= cookie->inval_counter;

 	if (!fscache_begin_cookie_access(cookie, why))
 		return -ENOBUFS;

 again:
 	spin_lock(&cookie->lock);

 	state = fscache_cookie_state(cookie);
 	_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);

 	switch (state) {
 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
 	case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
 	case FSCACHE_COOKIE_STATE_INVALIDATING:
 		goto wait_for_file_wrangling;
 	case FSCACHE_COOKIE_STATE_CREATING:
 		if (want_state == FSCACHE_WANT_PARAMS)
 			goto ready; /* There can be no content */
 		goto wait_for_file_wrangling;
 	case FSCACHE_COOKIE_STATE_ACTIVE:
 		goto ready;
 	case FSCACHE_COOKIE_STATE_DROPPED:
 	case FSCACHE_COOKIE_STATE_RELINQUISHING:
 		WARN(1, "Can't use cookie in state %u\n", cookie->state);
 		goto not_live;
 	default:
 		goto not_live;
 	}

 ready:
 	spin_unlock(&cookie->lock);
 	if (!cookie->volume->cache->ops->begin_operation(cres, want_state))
 		goto failed;
 	return 0;

 wait_for_file_wrangling:
 	spin_unlock(&cookie->lock);
 	trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
 			     atomic_read(&cookie->n_accesses),
 			     fscache_access_io_wait);
 	timeo = wait_var_event_timeout(&cookie->state,
 				       fscache_cookie_state(cookie) != state, 20 * HZ);
 	if (timeo <= 1 && !once_only) {
 		pr_warn("%s: cookie state change wait timed out: cookie->state=%u state=%u",
 			__func__, fscache_cookie_state(cookie), state);
 		fscache_print_cookie(cookie, 'O');
 		once_only = true;
 	}
 	goto again;

 not_live:
 	spin_unlock(&cookie->lock);
 failed:
 	cres->cache_priv = NULL;
 	cres->ops = NULL;
 	fscache_end_cookie_access(cookie, fscache_access_io_not_live);
 	_leave(" = -ENOBUFS");
 	return -ENOBUFS;
 }

 int __fscache_begin_read_operation(struct netfs_cache_resources *cres,
 				   struct fscache_cookie *cookie)
 {
 	return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
 				       fscache_access_io_read);
 }
 EXPORT_SYMBOL(__fscache_begin_read_operation);

 int __fscache_begin_write_operation(struct netfs_cache_resources *cres,
 				    struct fscache_cookie *cookie)
 {
 	return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
 				       fscache_access_io_write);
 }
 EXPORT_SYMBOL(__fscache_begin_write_operation);

 /**
  * fscache_set_page_dirty - Mark page dirty and pin a cache object for writeback
  * @page: The page being dirtied
  * @cookie: The cookie referring to the cache object
  *
  * Set the dirty flag on a page and pin an in-use cache object in memory when
  * dirtying a page so that writeback can later write to it.  This is intended
  * to be called from the filesystem's ->set_page_dirty() method.
  *
  *  Returns 1 if PG_dirty was set on the page, 0 otherwise.
  */
 int fscache_set_page_dirty(struct page *page, struct fscache_cookie *cookie)
 {
 	struct inode *inode = page->mapping->host;
 	bool need_use = false;

 	_enter("");

 	if (!__set_page_dirty_nobuffers(page))
 		return 0;
 	if (!fscache_cookie_valid(cookie))
 		return 1;

 	if (!(inode->i_state & I_PINNING_FSCACHE_WB)) {
 		spin_lock(&inode->i_lock);
 		if (!(inode->i_state & I_PINNING_FSCACHE_WB)) {
 			inode->i_state |= I_PINNING_FSCACHE_WB;
 			need_use = true;
 		}
 		spin_unlock(&inode->i_lock);

 		if (need_use)
 			fscache_use_cookie(cookie, true);
 	}
 	return 1;
 }
 EXPORT_SYMBOL(fscache_set_page_dirty);

 struct fscache_write_request {
 	struct netfs_cache_resources cache_resources;
 	struct address_space	*mapping;
 	loff_t			start;
 	size_t			len;
 	bool			set_bits;
 	netfs_io_terminated_t	term_func;
 	void			*term_func_priv;
 };

 void __fscache_clear_page_bits(struct address_space *mapping,
 			       loff_t start, size_t len)
 {
 	pgoff_t first = start / PAGE_SIZE;
 	pgoff_t last = (start + len - 1) / PAGE_SIZE;
 	struct page *page;

 	if (len) {
 		XA_STATE(xas, &mapping->i_pages, first);

 		rcu_read_lock();
 		xas_for_each(&xas, page, last) {
 			end_page_fscache(page);
 		}
 		rcu_read_unlock();
 	}
 }
 EXPORT_SYMBOL(__fscache_clear_page_bits);

 /*
  * Deal with the completion of writing the data to the cache.
  */
 static void fscache_wreq_done(void *priv, ssize_t transferred_or_error,
 			      bool was_async)
 {
 	struct fscache_write_request *wreq = priv;

 	fscache_clear_page_bits(fscache_cres_cookie(&wreq->cache_resources),
 				wreq->mapping, wreq->start, wreq->len,
 				wreq->set_bits);

 	if (wreq->term_func)
 		wreq->term_func(wreq->term_func_priv, transferred_or_error,
 				was_async);
 	fscache_end_operation(&wreq->cache_resources);
 	kfree(wreq);
 }

 void __fscache_write_to_cache(struct fscache_cookie *cookie,
 			      struct address_space *mapping,
 			      loff_t start, size_t len, loff_t i_size,
 			      netfs_io_terminated_t term_func,
 			      void *term_func_priv,
 			      bool cond)
 {
 	struct fscache_write_request *wreq;
 	struct netfs_cache_resources *cres;
 	struct iov_iter iter;
 	int ret = -ENOBUFS;

 	if (len == 0)
 		goto abandon;

 	_enter("%llx,%zx", start, len);

 	wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS);
 	if (!wreq)
 		goto abandon;
 	wreq->mapping		= mapping;
 	wreq->start		= start;
 	wreq->len		= len;
 	wreq->set_bits		= cond;
 	wreq->term_func		= term_func;
 	wreq->term_func_priv	= term_func_priv;

 	cres = &wreq->cache_resources;
 	if (fscache_begin_operation(cres, cookie, FSCACHE_WANT_WRITE,
 				    fscache_access_io_write) < 0)
 		goto abandon_free;

 	ret = cres->ops->prepare_write(cres, &start, &len, i_size, false);
 	if (ret < 0)
 		goto abandon_end;

 	/* TODO: Consider clearing page bits now for space the write isn't
 	 * covering.  This is more complicated than it appears when THPs are
 	 * taken into account.
 	 */

 	iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
 	fscache_write(cres, start, &iter, fscache_wreq_done, wreq);
 	return;

 abandon_end:
 	return fscache_wreq_done(wreq, ret, false);
 abandon_free:
 	kfree(wreq);
 abandon:
 	fscache_clear_page_bits(cookie, mapping, start, len, cond);
 	if (term_func)
 		term_func(term_func_priv, ret, false);
 }
 EXPORT_SYMBOL(__fscache_write_to_cache);

 /*
  * Change the size of a backing object.
  */
 void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
 {
 	struct netfs_cache_resources cres;

 	trace_fscache_resize(cookie, new_size);
 	if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE,
 				    fscache_access_io_resize) == 0) {
 		fscache_stat(&fscache_n_resizes);
 		set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);

 		/* We cannot defer a resize as we need to do it inside the
 		 * netfs's inode lock so that we're serialised with respect to
 		 * writes.
 		 */
 		cookie->volume->cache->ops->resize_cookie(&cres, new_size);
 		fscache_end_operation(&cres);
 	} else {
 		fscache_stat(&fscache_n_resizes_null);
 	}
 }
 EXPORT_SYMBOL(__fscache_resize_cookie);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* Cache data I/O routines
	*
	* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*/
	#define FSCACHE_DEBUG_LEVEL OPERATION
	#include <linux/fscache-cache.h>
	#include <linux/uio.h>
	#include <linux/bvec.h>
	#include <linux/slab.h>
	#include <linux/uio.h>
	#include "internal.h"

	/**
	* fscache_wait_for_operation - Wait for an object become accessible
	* @cres: The cache resources for the operation being performed
	* @want_state: The minimum state the object must be at
	*
	* See if the target cache object is at the specified minimum state of
	* accessibility yet, and if not, wait for it.
	*/
	bool fscache_wait_for_operation(struct netfs_cache_resources *cres,
	enum fscache_want_state want_state)
	{
	struct fscache_cookie *cookie = fscache_cres_cookie(cres);
	enum fscache_cookie_state state;

	again:
	if (!fscache_cache_is_live(cookie->volume->cache)) {
	_leave(" [broken]");
	return false;
	}

	state = fscache_cookie_state(cookie);
	_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);

	switch (state) {
	case FSCACHE_COOKIE_STATE_CREATING:
	case FSCACHE_COOKIE_STATE_INVALIDATING:
	if (want_state == FSCACHE_WANT_PARAMS)
	goto ready; /* There can be no content */
	fallthrough;
	case FSCACHE_COOKIE_STATE_LOOKING_UP:
	case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
	wait_var_event(&cookie->state,
	fscache_cookie_state(cookie) != state);
	goto again;

	case FSCACHE_COOKIE_STATE_ACTIVE:
	goto ready;
	case FSCACHE_COOKIE_STATE_DROPPED:
	case FSCACHE_COOKIE_STATE_RELINQUISHING:
	default:
	_leave(" [not live]");
	return false;
	}

	ready:
	if (!cres->cache_priv2)
	return cookie->volume->cache->ops->begin_operation(cres, want_state);
	return true;
	}
	EXPORT_SYMBOL(fscache_wait_for_operation);

	/*
	* Begin an I/O operation on the cache, waiting till we reach the right state.
	*
	* Attaches the resources required to the operation resources record.
	*/
	static int fscache_begin_operation(struct netfs_cache_resources *cres,
	struct fscache_cookie *cookie,
	enum fscache_want_state want_state,
	enum fscache_access_trace why)
	{
	enum fscache_cookie_state state;
	long timeo;
	bool once_only = false;

	cres->ops = NULL;
	cres->cache_priv = cookie;
	cres->cache_priv2 = NULL;
	cres->debug_id = cookie->debug_id;
	cres->inval_counter = cookie->inval_counter;

	if (!fscache_begin_cookie_access(cookie, why))
	return -ENOBUFS;

	again:
	spin_lock(&cookie->lock);

	state = fscache_cookie_state(cookie);
	_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);

	switch (state) {
	case FSCACHE_COOKIE_STATE_LOOKING_UP:
	case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
	case FSCACHE_COOKIE_STATE_INVALIDATING:
	goto wait_for_file_wrangling;
	case FSCACHE_COOKIE_STATE_CREATING:
	if (want_state == FSCACHE_WANT_PARAMS)
	goto ready; /* There can be no content */
	goto wait_for_file_wrangling;
	case FSCACHE_COOKIE_STATE_ACTIVE:
	goto ready;
	case FSCACHE_COOKIE_STATE_DROPPED:
	case FSCACHE_COOKIE_STATE_RELINQUISHING:
	WARN(1, "Can't use cookie in state %u\n", cookie->state);
	goto not_live;
	default:
	goto not_live;
	}

	ready:
	spin_unlock(&cookie->lock);
	if (!cookie->volume->cache->ops->begin_operation(cres, want_state))
	goto failed;
	return 0;

	wait_for_file_wrangling:
	spin_unlock(&cookie->lock);
	trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
	atomic_read(&cookie->n_accesses),
	fscache_access_io_wait);
	timeo = wait_var_event_timeout(&cookie->state,
	fscache_cookie_state(cookie) != state, 20 * HZ);
	if (timeo <= 1 && !once_only) {
	pr_warn("%s: cookie state change wait timed out: cookie->state=%u state=%u",
	__func__, fscache_cookie_state(cookie), state);
	fscache_print_cookie(cookie, 'O');
	once_only = true;
	}
	goto again;

	not_live:
	spin_unlock(&cookie->lock);
	failed:
	cres->cache_priv = NULL;
	cres->ops = NULL;
	fscache_end_cookie_access(cookie, fscache_access_io_not_live);
	_leave(" = -ENOBUFS");
	return -ENOBUFS;
	}

	int __fscache_begin_read_operation(struct netfs_cache_resources *cres,
	struct fscache_cookie *cookie)
	{
	return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
	fscache_access_io_read);
	}
	EXPORT_SYMBOL(__fscache_begin_read_operation);

	int __fscache_begin_write_operation(struct netfs_cache_resources *cres,
	struct fscache_cookie *cookie)
	{
	return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
	fscache_access_io_write);
	}
	EXPORT_SYMBOL(__fscache_begin_write_operation);

	/**
	* fscache_set_page_dirty - Mark page dirty and pin a cache object for writeback
	* @page: The page being dirtied
	* @cookie: The cookie referring to the cache object
	*
	* Set the dirty flag on a page and pin an in-use cache object in memory when
	* dirtying a page so that writeback can later write to it. This is intended
	* to be called from the filesystem's ->set_page_dirty() method.
	*
	* Returns 1 if PG_dirty was set on the page, 0 otherwise.
	*/
	int fscache_set_page_dirty(struct page page, struct fscache_cookie cookie)
	{
	struct inode *inode = page->mapping->host;
	bool need_use = false;

	_enter("");

	if (!__set_page_dirty_nobuffers(page))
	return 0;
	if (!fscache_cookie_valid(cookie))
	return 1;

	if (!(inode->i_state & I_PINNING_FSCACHE_WB)) {
	spin_lock(&inode->i_lock);
	if (!(inode->i_state & I_PINNING_FSCACHE_WB)) {
	inode->i_state \|= I_PINNING_FSCACHE_WB;
	need_use = true;
	}
	spin_unlock(&inode->i_lock);

	if (need_use)
	fscache_use_cookie(cookie, true);
	}
	return 1;
	}
	EXPORT_SYMBOL(fscache_set_page_dirty);

	struct fscache_write_request {
	struct netfs_cache_resources cache_resources;
	struct address_space *mapping;
	loff_t start;
	size_t len;
	bool set_bits;
	netfs_io_terminated_t term_func;
	void *term_func_priv;
	};

	void __fscache_clear_page_bits(struct address_space *mapping,
	loff_t start, size_t len)
	{
	pgoff_t first = start / PAGE_SIZE;
	pgoff_t last = (start + len - 1) / PAGE_SIZE;
	struct page *page;

	if (len) {
	XA_STATE(xas, &mapping->i_pages, first);

	rcu_read_lock();
	xas_for_each(&xas, page, last) {
	end_page_fscache(page);
	}
	rcu_read_unlock();
	}
	}
	EXPORT_SYMBOL(__fscache_clear_page_bits);

	/*
	* Deal with the completion of writing the data to the cache.
	*/
	static void fscache_wreq_done(void *priv, ssize_t transferred_or_error,
	bool was_async)
	{
	struct fscache_write_request *wreq = priv;

	fscache_clear_page_bits(fscache_cres_cookie(&wreq->cache_resources),
	wreq->mapping, wreq->start, wreq->len,
	wreq->set_bits);

	if (wreq->term_func)
	wreq->term_func(wreq->term_func_priv, transferred_or_error,
	was_async);
	fscache_end_operation(&wreq->cache_resources);
	kfree(wreq);
	}

	void __fscache_write_to_cache(struct fscache_cookie *cookie,
	struct address_space *mapping,
	loff_t start, size_t len, loff_t i_size,
	netfs_io_terminated_t term_func,
	void *term_func_priv,
	bool cond)
	{
	struct fscache_write_request *wreq;
	struct netfs_cache_resources *cres;
	struct iov_iter iter;
	int ret = -ENOBUFS;

	if (len == 0)
	goto abandon;

	_enter("%llx,%zx", start, len);

	wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS);
	if (!wreq)
	goto abandon;
	wreq->mapping = mapping;
	wreq->start = start;
	wreq->len = len;
	wreq->set_bits = cond;
	wreq->term_func = term_func;
	wreq->term_func_priv = term_func_priv;

	cres = &wreq->cache_resources;
	if (fscache_begin_operation(cres, cookie, FSCACHE_WANT_WRITE,
	fscache_access_io_write) < 0)
	goto abandon_free;

	ret = cres->ops->prepare_write(cres, &start, &len, i_size, false);
	if (ret < 0)
	goto abandon_end;

	/* TODO: Consider clearing page bits now for space the write isn't
	* covering. This is more complicated than it appears when THPs are
	* taken into account.
	*/

	iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
	fscache_write(cres, start, &iter, fscache_wreq_done, wreq);
	return;

	abandon_end:
	return fscache_wreq_done(wreq, ret, false);
	abandon_free:
	kfree(wreq);
	abandon:
	fscache_clear_page_bits(cookie, mapping, start, len, cond);
	if (term_func)
	term_func(term_func_priv, ret, false);
	}
	EXPORT_SYMBOL(__fscache_write_to_cache);

	/*
	* Change the size of a backing object.
	*/
	void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
	{
	struct netfs_cache_resources cres;

	trace_fscache_resize(cookie, new_size);
	if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE,
	fscache_access_io_resize) == 0) {
	fscache_stat(&fscache_n_resizes);
	set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);

	/* We cannot defer a resize as we need to do it inside the
	* netfs's inode lock so that we're serialised with respect to
	* writes.
	*/
	cookie->volume->cache->ops->resize_cookie(&cres, new_size);
	fscache_end_operation(&cres);
	} else {
	fscache_stat(&fscache_n_resizes_null);
	}
	}
	EXPORT_SYMBOL(__fscache_resize_cookie);