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From: Namjae Jeon <namjae.jeon@samsung.com>
To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Cc: gregkh@linuxfoundation.org, valdis.kletnieks@vt.edu, hch@lst.de,
	sj1557.seo@samsung.com, linkinjeon@gmail.com,
	pali.rohar@gmail.com, arnd@arndb.de,
	Namjae Jeon <namjae.jeon@samsung.com>
Subject: [PATCH v10 08/14] exfat: add exfat cache
Date: Wed, 15 Jan 2020 17:24:41 +0900
Message-ID: <20200115082447.19520-9-namjae.jeon@samsung.com> (raw)
In-Reply-To: <20200115082447.19520-1-namjae.jeon@samsung.com>

This adds the implementation of exfat cache.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
---
 fs/exfat/cache.c | 325 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 325 insertions(+)
 create mode 100644 fs/exfat/cache.c

diff --git a/fs/exfat/cache.c b/fs/exfat/cache.c
new file mode 100644
index 000000000000..03d0824fc368
--- /dev/null
+++ b/fs/exfat/cache.c
@@ -0,0 +1,325 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  linux/fs/fat/cache.c
+ *
+ *  Written 1992,1993 by Werner Almesberger
+ *
+ *  Mar 1999. AV. Changed cache, so that it uses the starting cluster instead
+ *	of inode number.
+ *  May 1999. AV. Fixed the bogosity with FAT32 (read "FAT28"). Fscking lusers.
+ *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/slab.h>
+#include <asm/unaligned.h>
+#include <linux/buffer_head.h>
+
+#include "exfat_raw.h"
+#include "exfat_fs.h"
+
+#define EXFAT_CACHE_VALID	0
+#define EXFAT_MAX_CACHE		16
+
+struct exfat_cache {
+	struct list_head cache_list;
+	unsigned int nr_contig;	/* number of contiguous clusters */
+	unsigned int fcluster;	/* cluster number in the file. */
+	unsigned int dcluster;	/* cluster number on disk. */
+};
+
+struct exfat_cache_id {
+	unsigned int id;
+	unsigned int nr_contig;
+	unsigned int fcluster;
+	unsigned int dcluster;
+};
+
+static struct kmem_cache *exfat_cachep;
+
+static void exfat_cache_init_once(void *c)
+{
+	struct exfat_cache *cache = (struct exfat_cache *)c;
+
+	INIT_LIST_HEAD(&cache->cache_list);
+}
+
+int exfat_cache_init(void)
+{
+	exfat_cachep = kmem_cache_create("exfat_cache",
+				sizeof(struct exfat_cache),
+				0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
+				exfat_cache_init_once);
+	if (!exfat_cachep)
+		return -ENOMEM;
+	return 0;
+}
+
+void exfat_cache_shutdown(void)
+{
+	if (!exfat_cachep)
+		return;
+	kmem_cache_destroy(exfat_cachep);
+}
+
+void exfat_cache_init_inode(struct inode *inode)
+{
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+
+	spin_lock_init(&ei->cache_lru_lock);
+	ei->nr_caches = 0;
+	ei->cache_valid_id = EXFAT_CACHE_VALID + 1;
+	INIT_LIST_HEAD(&ei->cache_lru);
+}
+
+static inline struct exfat_cache *exfat_cache_alloc(void)
+{
+	return kmem_cache_alloc(exfat_cachep, GFP_NOFS);
+}
+
+static inline void exfat_cache_free(struct exfat_cache *cache)
+{
+	WARN_ON(!list_empty(&cache->cache_list));
+	kmem_cache_free(exfat_cachep, cache);
+}
+
+static inline void exfat_cache_update_lru(struct inode *inode,
+		struct exfat_cache *cache)
+{
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+
+	if (ei->cache_lru.next != &cache->cache_list)
+		list_move(&cache->cache_list, &ei->cache_lru);
+}
+
+static unsigned int exfat_cache_lookup(struct inode *inode,
+		unsigned int fclus, struct exfat_cache_id *cid,
+		unsigned int *cached_fclus, unsigned int *cached_dclus)
+{
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+	static struct exfat_cache nohit = { .fcluster = 0, };
+	struct exfat_cache *hit = &nohit, *p;
+	unsigned int offset = EXFAT_EOF_CLUSTER;
+
+	spin_lock(&ei->cache_lru_lock);
+	list_for_each_entry(p, &ei->cache_lru, cache_list) {
+		/* Find the cache of "fclus" or nearest cache. */
+		if (p->fcluster <= fclus && hit->fcluster < p->fcluster) {
+			hit = p;
+			if (hit->fcluster + hit->nr_contig < fclus) {
+				offset = hit->nr_contig;
+			} else {
+				offset = fclus - hit->fcluster;
+				break;
+			}
+		}
+	}
+	if (hit != &nohit) {
+		exfat_cache_update_lru(inode, hit);
+
+		cid->id = ei->cache_valid_id;
+		cid->nr_contig = hit->nr_contig;
+		cid->fcluster = hit->fcluster;
+		cid->dcluster = hit->dcluster;
+		*cached_fclus = cid->fcluster + offset;
+		*cached_dclus = cid->dcluster + offset;
+	}
+	spin_unlock(&ei->cache_lru_lock);
+
+	return offset;
+}
+
+static struct exfat_cache *exfat_cache_merge(struct inode *inode,
+		struct exfat_cache_id *new)
+{
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+	struct exfat_cache *p;
+
+	list_for_each_entry(p, &ei->cache_lru, cache_list) {
+		/* Find the same part as "new" in cluster-chain. */
+		if (p->fcluster == new->fcluster) {
+			if (new->nr_contig > p->nr_contig)
+				p->nr_contig = new->nr_contig;
+			return p;
+		}
+	}
+	return NULL;
+}
+
+static void exfat_cache_add(struct inode *inode,
+		struct exfat_cache_id *new)
+{
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+	struct exfat_cache *cache, *tmp;
+
+	if (new->fcluster == EXFAT_EOF_CLUSTER) /* dummy cache */
+		return;
+
+	spin_lock(&ei->cache_lru_lock);
+	if (new->id != EXFAT_CACHE_VALID &&
+	    new->id != ei->cache_valid_id)
+		goto unlock;	/* this cache was invalidated */
+
+	cache = exfat_cache_merge(inode, new);
+	if (cache == NULL) {
+		if (ei->nr_caches < EXFAT_MAX_CACHE) {
+			ei->nr_caches++;
+			spin_unlock(&ei->cache_lru_lock);
+
+			tmp = exfat_cache_alloc();
+			if (!tmp) {
+				spin_lock(&ei->cache_lru_lock);
+				ei->nr_caches--;
+				spin_unlock(&ei->cache_lru_lock);
+				return;
+			}
+
+			spin_lock(&ei->cache_lru_lock);
+			cache = exfat_cache_merge(inode, new);
+			if (cache != NULL) {
+				ei->nr_caches--;
+				exfat_cache_free(tmp);
+				goto out_update_lru;
+			}
+			cache = tmp;
+		} else {
+			struct list_head *p = ei->cache_lru.prev;
+
+			cache = list_entry(p,
+					struct exfat_cache, cache_list);
+		}
+		cache->fcluster = new->fcluster;
+		cache->dcluster = new->dcluster;
+		cache->nr_contig = new->nr_contig;
+	}
+out_update_lru:
+	exfat_cache_update_lru(inode, cache);
+unlock:
+	spin_unlock(&ei->cache_lru_lock);
+}
+
+/*
+ * Cache invalidation occurs rarely, thus the LRU chain is not updated. It
+ * fixes itself after a while.
+ */
+static void __exfat_cache_inval_inode(struct inode *inode)
+{
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+	struct exfat_cache *cache;
+
+	while (!list_empty(&ei->cache_lru)) {
+		cache = list_entry(ei->cache_lru.next,
+				   struct exfat_cache, cache_list);
+		list_del_init(&cache->cache_list);
+		ei->nr_caches--;
+		exfat_cache_free(cache);
+	}
+	/* Update. The copy of caches before this id is discarded. */
+	ei->cache_valid_id++;
+	if (ei->cache_valid_id == EXFAT_CACHE_VALID)
+		ei->cache_valid_id++;
+}
+
+void exfat_cache_inval_inode(struct inode *inode)
+{
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+
+	spin_lock(&ei->cache_lru_lock);
+	__exfat_cache_inval_inode(inode);
+	spin_unlock(&ei->cache_lru_lock);
+}
+
+static inline int cache_contiguous(struct exfat_cache_id *cid,
+		unsigned int dclus)
+{
+	cid->nr_contig++;
+	return cid->dcluster + cid->nr_contig == dclus;
+}
+
+static inline void cache_init(struct exfat_cache_id *cid,
+		unsigned int fclus, unsigned int dclus)
+{
+	cid->id = EXFAT_CACHE_VALID;
+	cid->fcluster = fclus;
+	cid->dcluster = dclus;
+	cid->nr_contig = 0;
+}
+
+int exfat_get_cluster(struct inode *inode, unsigned int cluster,
+		unsigned int *fclus, unsigned int *dclus,
+		unsigned int *last_dclus, int allow_eof)
+{
+	struct super_block *sb = inode->i_sb;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	unsigned int limit = sbi->num_clusters;
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+	struct exfat_cache_id cid;
+	unsigned int content;
+
+	if (ei->start_clu == EXFAT_FREE_CLUSTER) {
+		exfat_fs_error(sb,
+			"invalid access to exfat cache (entry 0x%08x)",
+			ei->start_clu);
+		return -EIO;
+	}
+
+	*fclus = 0;
+	*dclus = ei->start_clu;
+	*last_dclus = *dclus;
+
+	/*
+	 * Don`t use exfat_cache if zero offset or non-cluster allocation
+	 */
+	if (cluster == 0 || *dclus == EXFAT_EOF_CLUSTER)
+		return 0;
+
+	cache_init(&cid, EXFAT_EOF_CLUSTER, EXFAT_EOF_CLUSTER);
+
+	if (exfat_cache_lookup(inode, cluster, &cid, fclus, dclus) ==
+			EXFAT_EOF_CLUSTER) {
+		/*
+		 * dummy, always not contiguous
+		 * This is reinitialized by cache_init(), later.
+		 */
+		WARN_ON(cid.id != EXFAT_CACHE_VALID ||
+			cid.fcluster != EXFAT_EOF_CLUSTER ||
+			cid.dcluster != EXFAT_EOF_CLUSTER ||
+			cid.nr_contig != 0);
+	}
+
+	if (*fclus == cluster)
+		return 0;
+
+	while (*fclus < cluster) {
+		/* prevent the infinite loop of cluster chain */
+		if (*fclus > limit) {
+			exfat_fs_error(sb,
+				"detected the cluster chain loop (i_pos %u)",
+				(*fclus));
+			return -EIO;
+		}
+
+		if (exfat_ent_get(sb, *dclus, &content))
+			return -EIO;
+
+		*last_dclus = *dclus;
+		*dclus = content;
+		(*fclus)++;
+
+		if (content == EXFAT_EOF_CLUSTER) {
+			if (!allow_eof) {
+				exfat_fs_error(sb,
+				       "invalid cluster chain (i_pos %u, last_clus 0x%08x is EOF)",
+				       *fclus, (*last_dclus));
+				return -EIO;
+			}
+
+			break;
+		}
+
+		if (!cache_contiguous(&cid, *dclus))
+			cache_init(&cid, *fclus, *dclus);
+	}
+
+	exfat_cache_add(inode, &cid);
+	return 0;
+}
-- 
2.17.1


  parent reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200115082818epcas1p4892a99345626188afd111ee263132458@epcas1p4.samsung.com>
2020-01-15  8:24 ` [PATCH v10 00/14] add the latest exfat driver Namjae Jeon
     [not found]   ` <CGME20200115082819epcas1p3303009557f8bf670b47991530f380ef7@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 01/14] exfat: add in-memory and on-disk structures and headers Namjae Jeon
     [not found]   ` <CGME20200115082819epcas1p3825d5bed592a8378ad26254d07d59b18@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 02/14] exfat: add super block operations Namjae Jeon
     [not found]   ` <CGME20200115082820epcas1p34ebebebaf610fd61c4e9882fca8ddbd5@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 03/14] exfat: add inode operations Namjae Jeon
2020-01-15 10:25       ` Arnd Bergmann
2020-01-15 13:39         ` Namjae Jeon
2020-01-17  9:25       ` Pali Rohár
2020-01-17 11:17       ` Pali Rohár
     [not found]   ` <CGME20200115082821epcas1p3db1f70cf53185c40934c3a754c65e648@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 04/14] exfat: add directory operations Namjae Jeon
2020-01-17 11:13       ` Pali Rohár
     [not found]   ` <CGME20200115082821epcas1p4d76d8668dfac70ae3e3889d4ccb6c3ee@epcas1p4.samsung.com>
2020-01-15  8:24     ` [PATCH v10 05/14] exfat: add file operations Namjae Jeon
2020-01-15  9:56       ` Arnd Bergmann
2020-01-15 13:07         ` Namjae Jeon
2020-01-17  9:18       ` Pali Rohár
2020-01-17 12:12         ` Namjae Jeon
     [not found]   ` <CGME20200115082822epcas1p37aca37dad0aa9159d7eddde01edfeec2@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 06/14] exfat: add fat entry operations Namjae Jeon
     [not found]   ` <CGME20200115082822epcas1p384d080724d8bb0a8cd4c3e3015a0895c@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 07/14] exfat: add bitmap operations Namjae Jeon
     [not found]   ` <CGME20200115082823epcas1p27ec5ff6d384f148d826529f573173b04@epcas1p2.samsung.com>
2020-01-15  8:24     ` Namjae Jeon [this message]
     [not found]   ` <CGME20200115082824epcas1p4eb45d088c2f88149acb94563c4a9b276@epcas1p4.samsung.com>
2020-01-15  8:24     ` [PATCH v10 09/14] exfat: add misc operations Namjae Jeon
2020-01-15 10:10       ` Arnd Bergmann
2020-01-15 13:30         ` Namjae Jeon
2020-01-15 13:38           ` Pali Rohár
2020-01-15 13:50             ` Arnd Bergmann
2020-01-15 14:24               ` Pali Rohár
2020-01-15 15:03                 ` Arnd Bergmann
2020-01-15 15:39                   ` Pali Rohár
2020-01-15 15:52                     ` Arnd Bergmann
2020-01-16 10:19                       ` Pali Rohár
2020-01-16 10:23                         ` Christoph Hellwig
2020-01-16 16:00                           ` Pali Rohár
2020-01-17  2:59                       ` Namjae Jeon
2020-01-17 10:13                         ` Arnd Bergmann
2020-01-17 12:13                           ` Namjae Jeon
     [not found]   ` <CGME20200115082824epcas1p23a0fa255a5833c6dcd2479b384f37740@epcas1p2.samsung.com>
2020-01-15  8:24     ` [PATCH v10 10/14] exfat: add nls operations Namjae Jeon
     [not found]   ` <CGME20200115082825epcas1p1f22ddca6dbf5d70e65d3b0e3c25c3a59@epcas1p1.samsung.com>
2020-01-15  8:24     ` [PATCH v10 11/14] exfat: add Kconfig and Makefile Namjae Jeon
2020-01-15  9:39       ` Pali Rohár
2020-01-17  4:22         ` Namjae Jeon
2020-01-17  9:12           ` Pali Rohár
2020-01-17 11:59             ` Namjae Jeon
     [not found]   ` <CGME20200115082825epcas1p4a0d63d53d8737a84fe8867bc1e63811e@epcas1p4.samsung.com>
2020-01-15  8:24     ` [PATCH v10 12/14] exfat: add exfat in fs/Kconfig and fs/Makefile Namjae Jeon
     [not found]   ` <CGME20200115082826epcas1p117191a39ecccaef5a9b5cbe77b05c5a5@epcas1p1.samsung.com>
2020-01-15  8:24     ` [PATCH v10 13/14] MAINTAINERS: add exfat filesystem Namjae Jeon
     [not found]   ` <CGME20200115082826epcas1p3475ce2b4d03234dc96ced428be582eb3@epcas1p3.samsung.com>
2020-01-15  8:24     ` [PATCH v10 14/14] staging: exfat: make staging/exfat and fs/exfat mutually exclusive Namjae Jeon
2020-01-15  8:56       ` Greg KH
2020-01-15 13:06         ` Namjae Jeon
2020-01-15  9:47   ` [PATCH v10 00/14] add the latest exfat driver Pali Rohár
2020-01-15 13:05     ` Namjae Jeon
2020-01-16 10:51     ` Christoph Hellwig
2020-01-16 11:32       ` Pali Rohár
2020-01-16 13:01       ` Greg KH

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