fs/9p/cache.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * V9FS cache definitions.
  *
  *  Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
  */

 #include <linux/jiffies.h>
 #include <linux/file.h>
 #include <linux/slab.h>
 #include <linux/stat.h>
 #include <linux/sched.h>
 #include <linux/fs.h>
 #include <net/9p/9p.h>

 #include "v9fs.h"
 #include "cache.h"

 #define CACHETAG_LEN  11

 struct fscache_netfs v9fs_cache_netfs = {
 	.name 		= "9p",
 	.version 	= 0,
 };

 /**
  * v9fs_random_cachetag - Generate a random tag to be associated
  *			  with a new cache session.
  *
  * The value of jiffies is used for a fairly randomly cache tag.
  */

 static
 int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
 {
 	v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
 	if (!v9ses->cachetag)
 		return -ENOMEM;

 	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
 }

 const struct fscache_cookie_def v9fs_cache_session_index_def = {
 	.name		= "9P.session",
 	.type		= FSCACHE_COOKIE_TYPE_INDEX,
 };

 void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
 {
 	/* If no cache session tag was specified, we generate a random one. */
 	if (!v9ses->cachetag) {
 		if (v9fs_random_cachetag(v9ses) < 0) {
 			v9ses->fscache = NULL;
 			return;
 		}
 	}

 	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
 						&v9fs_cache_session_index_def,
 						v9ses->cachetag,
 						strlen(v9ses->cachetag),
 						NULL, 0,
 						v9ses, 0, true);
 	p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
 		 v9ses, v9ses->fscache);
 }

 void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
 {
 	p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
 		 v9ses, v9ses->fscache);
 	fscache_relinquish_cookie(v9ses->fscache, NULL, false);
 	v9ses->fscache = NULL;
 }

 static enum
 fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
 					    const void *buffer,
 					    uint16_t buflen,
 					    loff_t object_size)
 {
 	const struct v9fs_inode *v9inode = cookie_netfs_data;

 	if (buflen != sizeof(v9inode->qid.version))
 		return FSCACHE_CHECKAUX_OBSOLETE;

 	if (memcmp(buffer, &v9inode->qid.version,
 		   sizeof(v9inode->qid.version)))
 		return FSCACHE_CHECKAUX_OBSOLETE;

 	return FSCACHE_CHECKAUX_OKAY;
 }

 const struct fscache_cookie_def v9fs_cache_inode_index_def = {
 	.name		= "9p.inode",
 	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
 	.check_aux	= v9fs_cache_inode_check_aux,
 };

 void v9fs_cache_inode_get_cookie(struct inode *inode)
 {
 	struct v9fs_inode *v9inode;
 	struct v9fs_session_info *v9ses;

 	if (!S_ISREG(inode->i_mode))
 		return;

 	v9inode = V9FS_I(inode);
 	if (v9inode->fscache)
 		return;

 	v9ses = v9fs_inode2v9ses(inode);
 	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 						  &v9fs_cache_inode_index_def,
 						  &v9inode->qid.path,
 						  sizeof(v9inode->qid.path),
 						  &v9inode->qid.version,
 						  sizeof(v9inode->qid.version),
 						  v9inode,
 						  i_size_read(&v9inode->vfs_inode),
 						  true);

 	p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
 		 inode, v9inode->fscache);
 }

 void v9fs_cache_inode_put_cookie(struct inode *inode)
 {
 	struct v9fs_inode *v9inode = V9FS_I(inode);

 	if (!v9inode->fscache)
 		return;
 	p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
 		 inode, v9inode->fscache);

 	fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
 				  false);
 	v9inode->fscache = NULL;
 }

 void v9fs_cache_inode_flush_cookie(struct inode *inode)
 {
 	struct v9fs_inode *v9inode = V9FS_I(inode);

 	if (!v9inode->fscache)
 		return;
 	p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
 		 inode, v9inode->fscache);

 	fscache_relinquish_cookie(v9inode->fscache, NULL, true);
 	v9inode->fscache = NULL;
 }

 void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
 {
 	struct v9fs_inode *v9inode = V9FS_I(inode);

 	if (!v9inode->fscache)
 		return;

 	mutex_lock(&v9inode->fscache_lock);

 	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 		v9fs_cache_inode_flush_cookie(inode);
 	else
 		v9fs_cache_inode_get_cookie(inode);

 	mutex_unlock(&v9inode->fscache_lock);
 }

 void v9fs_cache_inode_reset_cookie(struct inode *inode)
 {
 	struct v9fs_inode *v9inode = V9FS_I(inode);
 	struct v9fs_session_info *v9ses;
 	struct fscache_cookie *old;

 	if (!v9inode->fscache)
 		return;

 	old = v9inode->fscache;

 	mutex_lock(&v9inode->fscache_lock);
 	fscache_relinquish_cookie(v9inode->fscache, NULL, true);

 	v9ses = v9fs_inode2v9ses(inode);
 	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
 						  &v9fs_cache_inode_index_def,
 						  &v9inode->qid.path,
 						  sizeof(v9inode->qid.path),
 						  &v9inode->qid.version,
 						  sizeof(v9inode->qid.version),
 						  v9inode,
 						  i_size_read(&v9inode->vfs_inode),
 						  true);
 	p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
 		 inode, old, v9inode->fscache);

 	mutex_unlock(&v9inode->fscache_lock);
 }

 int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
 {
 	struct inode *inode = page->mapping->host;
 	struct v9fs_inode *v9inode = V9FS_I(inode);

 	BUG_ON(!v9inode->fscache);

 	return fscache_maybe_release_page(v9inode->fscache, page, gfp);
 }

 void __v9fs_fscache_invalidate_page(struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	struct v9fs_inode *v9inode = V9FS_I(inode);

 	BUG_ON(!v9inode->fscache);

 	if (PageFsCache(page)) {
 		fscache_wait_on_page_write(v9inode->fscache, page);
 		BUG_ON(!PageLocked(page));
 		fscache_uncache_page(v9inode->fscache, page);
 	}
 }

 static void v9fs_vfs_readpage_complete(struct page *page, void *data,
 				       int error)
 {
 	if (!error)
 		SetPageUptodate(page);

 	unlock_page(page);
 }

 /**
  * __v9fs_readpage_from_fscache - read a page from cache
  *
  * Returns 0 if the pages are in cache and a BIO is submitted,
  * 1 if the pages are not in cache and -error otherwise.
  */

 int __v9fs_readpage_from_fscache(struct inode *inode, struct page *page)
 {
 	int ret;
 	const struct v9fs_inode *v9inode = V9FS_I(inode);

 	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 	if (!v9inode->fscache)
 		return -ENOBUFS;

 	ret = fscache_read_or_alloc_page(v9inode->fscache,
 					 page,
 					 v9fs_vfs_readpage_complete,
 					 NULL,
 					 GFP_KERNEL);
 	switch (ret) {
 	case -ENOBUFS:
 	case -ENODATA:
 		p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
 		return 1;
 	case 0:
 		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 		return ret;
 	default:
 		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 		return ret;
 	}
 }

 /**
  * __v9fs_readpages_from_fscache - read multiple pages from cache
  *
  * Returns 0 if the pages are in cache and a BIO is submitted,
  * 1 if the pages are not in cache and -error otherwise.
  */

 int __v9fs_readpages_from_fscache(struct inode *inode,
 				  struct address_space *mapping,
 				  struct list_head *pages,
 				  unsigned *nr_pages)
 {
 	int ret;
 	const struct v9fs_inode *v9inode = V9FS_I(inode);

 	p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
 	if (!v9inode->fscache)
 		return -ENOBUFS;

 	ret = fscache_read_or_alloc_pages(v9inode->fscache,
 					  mapping, pages, nr_pages,
 					  v9fs_vfs_readpage_complete,
 					  NULL,
 					  mapping_gfp_mask(mapping));
 	switch (ret) {
 	case -ENOBUFS:
 	case -ENODATA:
 		p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
 		return 1;
 	case 0:
 		BUG_ON(!list_empty(pages));
 		BUG_ON(*nr_pages != 0);
 		p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
 		return ret;
 	default:
 		p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
 		return ret;
 	}
 }

 /**
  * __v9fs_readpage_to_fscache - write a page to the cache
  *
  */

 void __v9fs_readpage_to_fscache(struct inode *inode, struct page *page)
 {
 	int ret;
 	const struct v9fs_inode *v9inode = V9FS_I(inode);

 	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 	ret = fscache_write_page(v9inode->fscache, page,
 				 i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
 	p9_debug(P9_DEBUG_FSC, "ret =  %d\n", ret);
 	if (ret != 0)
 		v9fs_uncache_page(inode, page);
 }

 /*
  * wait for a page to complete writing to the cache
  */
 void __v9fs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
 {
 	const struct v9fs_inode *v9inode = V9FS_I(inode);
 	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
 	if (PageFsCache(page))
 		fscache_wait_on_page_write(v9inode->fscache, page);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* V9FS cache definitions.
	*
	* Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
	*/

	#include <linux/jiffies.h>
	#include <linux/file.h>
	#include <linux/slab.h>
	#include <linux/stat.h>
	#include <linux/sched.h>
	#include <linux/fs.h>
	#include <net/9p/9p.h>

	#include "v9fs.h"
	#include "cache.h"

	#define CACHETAG_LEN 11

	struct fscache_netfs v9fs_cache_netfs = {
	.name = "9p",
	.version = 0,
	};

	/**
	* v9fs_random_cachetag - Generate a random tag to be associated
	* with a new cache session.
	*
	* The value of jiffies is used for a fairly randomly cache tag.
	*/

	static
	int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
	{
	v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
	if (!v9ses->cachetag)
	return -ENOMEM;

	return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
	}

	const struct fscache_cookie_def v9fs_cache_session_index_def = {
	.name = "9P.session",
	.type = FSCACHE_COOKIE_TYPE_INDEX,
	};

	void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
	{
	/* If no cache session tag was specified, we generate a random one. */
	if (!v9ses->cachetag) {
	if (v9fs_random_cachetag(v9ses) < 0) {
	v9ses->fscache = NULL;
	return;
	}
	}

	v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
	&v9fs_cache_session_index_def,
	v9ses->cachetag,
	strlen(v9ses->cachetag),
	NULL, 0,
	v9ses, 0, true);
	p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
	v9ses, v9ses->fscache);
	}

	void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
	{
	p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
	v9ses, v9ses->fscache);
	fscache_relinquish_cookie(v9ses->fscache, NULL, false);
	v9ses->fscache = NULL;
	}

	static enum
	fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
	const void *buffer,
	uint16_t buflen,
	loff_t object_size)
	{
	const struct v9fs_inode *v9inode = cookie_netfs_data;

	if (buflen != sizeof(v9inode->qid.version))
	return FSCACHE_CHECKAUX_OBSOLETE;

	if (memcmp(buffer, &v9inode->qid.version,
	sizeof(v9inode->qid.version)))
	return FSCACHE_CHECKAUX_OBSOLETE;

	return FSCACHE_CHECKAUX_OKAY;
	}

	const struct fscache_cookie_def v9fs_cache_inode_index_def = {
	.name = "9p.inode",
	.type = FSCACHE_COOKIE_TYPE_DATAFILE,
	.check_aux = v9fs_cache_inode_check_aux,
	};

	void v9fs_cache_inode_get_cookie(struct inode *inode)
	{
	struct v9fs_inode *v9inode;
	struct v9fs_session_info *v9ses;

	if (!S_ISREG(inode->i_mode))
	return;

	v9inode = V9FS_I(inode);
	if (v9inode->fscache)
	return;

	v9ses = v9fs_inode2v9ses(inode);
	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
	&v9fs_cache_inode_index_def,
	&v9inode->qid.path,
	sizeof(v9inode->qid.path),
	&v9inode->qid.version,
	sizeof(v9inode->qid.version),
	v9inode,
	i_size_read(&v9inode->vfs_inode),
	true);

	p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
	inode, v9inode->fscache);
	}

	void v9fs_cache_inode_put_cookie(struct inode *inode)
	{
	struct v9fs_inode *v9inode = V9FS_I(inode);

	if (!v9inode->fscache)
	return;
	p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
	inode, v9inode->fscache);

	fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
	false);
	v9inode->fscache = NULL;
	}

	void v9fs_cache_inode_flush_cookie(struct inode *inode)
	{
	struct v9fs_inode *v9inode = V9FS_I(inode);

	if (!v9inode->fscache)
	return;
	p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
	inode, v9inode->fscache);

	fscache_relinquish_cookie(v9inode->fscache, NULL, true);
	v9inode->fscache = NULL;
	}

	void v9fs_cache_inode_set_cookie(struct inode inode, struct file filp)
	{
	struct v9fs_inode *v9inode = V9FS_I(inode);

	if (!v9inode->fscache)
	return;

	mutex_lock(&v9inode->fscache_lock);

	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
	v9fs_cache_inode_flush_cookie(inode);
	else
	v9fs_cache_inode_get_cookie(inode);

	mutex_unlock(&v9inode->fscache_lock);
	}

	void v9fs_cache_inode_reset_cookie(struct inode *inode)
	{
	struct v9fs_inode *v9inode = V9FS_I(inode);
	struct v9fs_session_info *v9ses;
	struct fscache_cookie *old;

	if (!v9inode->fscache)
	return;

	old = v9inode->fscache;

	mutex_lock(&v9inode->fscache_lock);
	fscache_relinquish_cookie(v9inode->fscache, NULL, true);

	v9ses = v9fs_inode2v9ses(inode);
	v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
	&v9fs_cache_inode_index_def,
	&v9inode->qid.path,
	sizeof(v9inode->qid.path),
	&v9inode->qid.version,
	sizeof(v9inode->qid.version),
	v9inode,
	i_size_read(&v9inode->vfs_inode),
	true);
	p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
	inode, old, v9inode->fscache);

	mutex_unlock(&v9inode->fscache_lock);
	}

	int __v9fs_fscache_release_page(struct page *page, gfp_t gfp)
	{
	struct inode *inode = page->mapping->host;
	struct v9fs_inode *v9inode = V9FS_I(inode);

	BUG_ON(!v9inode->fscache);

	return fscache_maybe_release_page(v9inode->fscache, page, gfp);
	}

	void __v9fs_fscache_invalidate_page(struct page *page)
	{
	struct inode *inode = page->mapping->host;
	struct v9fs_inode *v9inode = V9FS_I(inode);

	BUG_ON(!v9inode->fscache);

	if (PageFsCache(page)) {
	fscache_wait_on_page_write(v9inode->fscache, page);
	BUG_ON(!PageLocked(page));
	fscache_uncache_page(v9inode->fscache, page);
	}
	}

	static void v9fs_vfs_readpage_complete(struct page page, void data,
	int error)
	{
	if (!error)
	SetPageUptodate(page);

	unlock_page(page);
	}

	/**
	* __v9fs_readpage_from_fscache - read a page from cache
	*
	* Returns 0 if the pages are in cache and a BIO is submitted,
	* 1 if the pages are not in cache and -error otherwise.
	*/

	int __v9fs_readpage_from_fscache(struct inode inode, struct page page)
	{
	int ret;
	const struct v9fs_inode *v9inode = V9FS_I(inode);

	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
	if (!v9inode->fscache)
	return -ENOBUFS;

	ret = fscache_read_or_alloc_page(v9inode->fscache,
	page,
	v9fs_vfs_readpage_complete,
	NULL,
	GFP_KERNEL);
	switch (ret) {
	case -ENOBUFS:
	case -ENODATA:
	p9_debug(P9_DEBUG_FSC, "page/inode not in cache %d\n", ret);
	return 1;
	case 0:
	p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
	return ret;
	default:
	p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
	return ret;
	}
	}

	/**
	* __v9fs_readpages_from_fscache - read multiple pages from cache
	*
	* Returns 0 if the pages are in cache and a BIO is submitted,
	* 1 if the pages are not in cache and -error otherwise.
	*/

	int __v9fs_readpages_from_fscache(struct inode *inode,
	struct address_space *mapping,
	struct list_head *pages,
	unsigned *nr_pages)
	{
	int ret;
	const struct v9fs_inode *v9inode = V9FS_I(inode);

	p9_debug(P9_DEBUG_FSC, "inode %p pages %u\n", inode, *nr_pages);
	if (!v9inode->fscache)
	return -ENOBUFS;

	ret = fscache_read_or_alloc_pages(v9inode->fscache,
	mapping, pages, nr_pages,
	v9fs_vfs_readpage_complete,
	NULL,
	mapping_gfp_mask(mapping));
	switch (ret) {
	case -ENOBUFS:
	case -ENODATA:
	p9_debug(P9_DEBUG_FSC, "pages/inodes not in cache %d\n", ret);
	return 1;
	case 0:
	BUG_ON(!list_empty(pages));
	BUG_ON(*nr_pages != 0);
	p9_debug(P9_DEBUG_FSC, "BIO submitted\n");
	return ret;
	default:
	p9_debug(P9_DEBUG_FSC, "ret %d\n", ret);
	return ret;
	}
	}

	/**
	* __v9fs_readpage_to_fscache - write a page to the cache
	*
	*/

	void __v9fs_readpage_to_fscache(struct inode inode, struct page page)
	{
	int ret;
	const struct v9fs_inode *v9inode = V9FS_I(inode);

	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
	ret = fscache_write_page(v9inode->fscache, page,
	i_size_read(&v9inode->vfs_inode), GFP_KERNEL);
	p9_debug(P9_DEBUG_FSC, "ret = %d\n", ret);
	if (ret != 0)
	v9fs_uncache_page(inode, page);
	}

	/*
	* wait for a page to complete writing to the cache
	*/
	void __v9fs_fscache_wait_on_page_write(struct inode inode, struct page page)
	{
	const struct v9fs_inode *v9inode = V9FS_I(inode);
	p9_debug(P9_DEBUG_FSC, "inode %p page %p\n", inode, page);
	if (PageFsCache(page))
	fscache_wait_on_page_write(v9inode->fscache, page);
	}