[deliverable/linux.git] / fs / fat / cache.c

/*
 *  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.
 */

#include <linux/slab.h>
#include "fat.h"

/* this must be > 0. */
#define FAT_MAX_CACHE	8

struct fat_cache {
	struct list_head cache_list;
	int nr_contig;	/* number of contiguous clusters */
	int fcluster;	/* cluster number in the file. */
	int dcluster;	/* cluster number on disk. */
};

struct fat_cache_id {
	unsigned int id;
	int nr_contig;
	int fcluster;
	int dcluster;
};

static inline int fat_max_cache(struct inode *inode)
{
	return FAT_MAX_CACHE;
}

static struct kmem_cache *fat_cache_cachep;

static void init_once(void *foo)
{
	struct fat_cache *cache = (struct fat_cache *)foo;

	INIT_LIST_HEAD(&cache->cache_list);
}

int __init fat_cache_init(void)
{
	fat_cache_cachep = kmem_cache_create("fat_cache",
				sizeof(struct fat_cache),
				0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
				init_once);
	if (fat_cache_cachep == NULL)
		return -ENOMEM;
	return 0;
}

void fat_cache_destroy(void)
{
	kmem_cache_destroy(fat_cache_cachep);
}

static inline struct fat_cache *fat_cache_alloc(struct inode *inode)
{
	return kmem_cache_alloc(fat_cache_cachep, GFP_NOFS);
}

static inline void fat_cache_free(struct fat_cache *cache)
{
	BUG_ON(!list_empty(&cache->cache_list));
	kmem_cache_free(fat_cache_cachep, cache);
}

static inline void fat_cache_update_lru(struct inode *inode,
					struct fat_cache *cache)
{
	if (MSDOS_I(inode)->cache_lru.next != &cache->cache_list)
		list_move(&cache->cache_list, &MSDOS_I(inode)->cache_lru);
}

static int fat_cache_lookup(struct inode *inode, int fclus,
			    struct fat_cache_id *cid,
			    int *cached_fclus, int *cached_dclus)
{
	static struct fat_cache nohit = { .fcluster = 0, };

	struct fat_cache *hit = &nohit, *p;
	int offset = -1;

	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
	list_for_each_entry(p, &MSDOS_I(inode)->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) {
		fat_cache_update_lru(inode, hit);

		cid->id = MSDOS_I(inode)->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(&MSDOS_I(inode)->cache_lru_lock);

	return offset;
}

static struct fat_cache *fat_cache_merge(struct inode *inode,
					 struct fat_cache_id *new)
{
	struct fat_cache *p;

	list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) {
		/* Find the same part as "new" in cluster-chain. */
		if (p->fcluster == new->fcluster) {
			BUG_ON(p->dcluster != new->dcluster);
			if (new->nr_contig > p->nr_contig)
				p->nr_contig = new->nr_contig;
			return p;
		}
	}
	return NULL;
}

static void fat_cache_add(struct inode *inode, struct fat_cache_id *new)
{
	struct fat_cache *cache, *tmp;

	if (new->fcluster == -1) /* dummy cache */
		return;

	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
	if (new->id != FAT_CACHE_VALID &&
	    new->id != MSDOS_I(inode)->cache_valid_id)
		goto out;	/* this cache was invalidated */

	cache = fat_cache_merge(inode, new);
	if (cache == NULL) {
		if (MSDOS_I(inode)->nr_caches < fat_max_cache(inode)) {
			MSDOS_I(inode)->nr_caches++;
			spin_unlock(&MSDOS_I(inode)->cache_lru_lock);

			tmp = fat_cache_alloc(inode);
			if (!tmp) {
				spin_lock(&MSDOS_I(inode)->cache_lru_lock);
				MSDOS_I(inode)->nr_caches--;
				spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
				return;
			}

			spin_lock(&MSDOS_I(inode)->cache_lru_lock);
			cache = fat_cache_merge(inode, new);
			if (cache != NULL) {
				MSDOS_I(inode)->nr_caches--;
				fat_cache_free(tmp);
				goto out_update_lru;
			}
			cache = tmp;
		} else {
			struct list_head *p = MSDOS_I(inode)->cache_lru.prev;
			cache = list_entry(p, struct fat_cache, cache_list);
		}
		cache->fcluster = new->fcluster;
		cache->dcluster = new->dcluster;
		cache->nr_contig = new->nr_contig;
	}
out_update_lru:
	fat_cache_update_lru(inode, cache);
out:
	spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
}

/*
 * Cache invalidation occurs rarely, thus the LRU chain is not updated. It
 * fixes itself after a while.
 */
static void __fat_cache_inval_inode(struct inode *inode)
{
	struct msdos_inode_info *i = MSDOS_I(inode);
	struct fat_cache *cache;

	while (!list_empty(&i->cache_lru)) {
		cache = list_entry(i->cache_lru.next,
				   struct fat_cache, cache_list);
		list_del_init(&cache->cache_list);
		i->nr_caches--;
		fat_cache_free(cache);
	}
	/* Update. The copy of caches before this id is discarded. */
	i->cache_valid_id++;
	if (i->cache_valid_id == FAT_CACHE_VALID)
		i->cache_valid_id++;
}

void fat_cache_inval_inode(struct inode *inode)
{
	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
	__fat_cache_inval_inode(inode);
	spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
}

static inline int cache_contiguous(struct fat_cache_id *cid, int dclus)
{
	cid->nr_contig++;
	return ((cid->dcluster + cid->nr_contig) == dclus);
}

static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus)
{
	cid->id = FAT_CACHE_VALID;
	cid->fcluster = fclus;
	cid->dcluster = dclus;
	cid->nr_contig = 0;
}

int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
{
	struct super_block *sb = inode->i_sb;
	const int limit = sb->s_maxbytes >> MSDOS_SB(sb)->cluster_bits;
	struct fat_entry fatent;
	struct fat_cache_id cid;
	int nr;

	BUG_ON(MSDOS_I(inode)->i_start == 0);

	*fclus = 0;
	*dclus = MSDOS_I(inode)->i_start;
	if (cluster == 0)
		return 0;

	if (fat_cache_lookup(inode, cluster, &cid, fclus, dclus) < 0) {
		/*
		 * dummy, always not contiguous
		 * This is reinitialized by cache_init(), later.
		 */
		cache_init(&cid, -1, -1);
	}

	fatent_init(&fatent);
	while (*fclus < cluster) {
		/* prevent the infinite loop of cluster chain */
		if (*fclus > limit) {
			fat_fs_error_ratelimit(sb,
					"%s: detected the cluster chain loop"
					" (i_pos %lld)", __func__,
					MSDOS_I(inode)->i_pos);
			nr = -EIO;
			goto out;
		}

		nr = fat_ent_read(inode, &fatent, *dclus);
		if (nr < 0)
			goto out;
		else if (nr == FAT_ENT_FREE) {
			fat_fs_error_ratelimit(sb,
				       "%s: invalid cluster chain (i_pos %lld)",
				       __func__,
				       MSDOS_I(inode)->i_pos);
			nr = -EIO;
			goto out;
		} else if (nr == FAT_ENT_EOF) {
			fat_cache_add(inode, &cid);
			goto out;
		}
		(*fclus)++;
		*dclus = nr;
		if (!cache_contiguous(&cid, *dclus))
			cache_init(&cid, *fclus, *dclus);
	}
	nr = 0;
	fat_cache_add(inode, &cid);
out:
	fatent_brelse(&fatent);
	return nr;
}

static int fat_bmap_cluster(struct inode *inode, int cluster)
{
	struct super_block *sb = inode->i_sb;
	int ret, fclus, dclus;

	if (MSDOS_I(inode)->i_start == 0)
		return 0;

	ret = fat_get_cluster(inode, cluster, &fclus, &dclus);
	if (ret < 0)
		return ret;
	else if (ret == FAT_ENT_EOF) {
		fat_fs_error(sb, "%s: request beyond EOF (i_pos %lld)",
			     __func__, MSDOS_I(inode)->i_pos);
		return -EIO;
	}
	return dclus;
}

int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
			   sector_t last_block,
			   unsigned long *mapped_blocks, sector_t *bmap)
{
	struct super_block *sb = inode->i_sb;
	struct msdos_sb_info *sbi = MSDOS_SB(sb);
	int cluster, offset;

	cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
	offset  = sector & (sbi->sec_per_clus - 1);
	cluster = fat_bmap_cluster(inode, cluster);
	if (cluster < 0)
		return cluster;
	else if (cluster) {
		*bmap = fat_clus_to_blknr(sbi, cluster) + offset;
		*mapped_blocks = sbi->sec_per_clus - offset;
		if (*mapped_blocks > last_block - sector)
			*mapped_blocks = last_block - sector;
	}

	return 0;
}

static int is_exceed_eof(struct inode *inode, sector_t sector,
			 sector_t *last_block, int create)
{
	struct super_block *sb = inode->i_sb;
	const unsigned long blocksize = sb->s_blocksize;
	const unsigned char blocksize_bits = sb->s_blocksize_bits;

	*last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
	if (sector >= *last_block) {
		if (!create)
			return 1;

		/*
		 * ->mmu_private can access on only allocation path.
		 * (caller must hold ->i_mutex)
		 */
		*last_block = (MSDOS_I(inode)->mmu_private + (blocksize - 1))
			>> blocksize_bits;
		if (sector >= *last_block)
			return 1;
	}

	return 0;
}

int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
	     unsigned long *mapped_blocks, int create, bool from_bmap)
{
	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
	sector_t last_block;

	*phys = 0;
	*mapped_blocks = 0;
	if ((sbi->fat_bits != 32) && (inode->i_ino == MSDOS_ROOT_INO)) {
		if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits)) {
			*phys = sector + sbi->dir_start;
			*mapped_blocks = 1;
		}
		return 0;
	}

	if (!from_bmap) {
		if (is_exceed_eof(inode, sector, &last_block, create))
			return 0;
	} else {
		last_block = inode->i_blocks >>
				(inode->i_sb->s_blocksize_bits - 9);
		if (sector >= last_block)
			return 0;
	}

	return fat_get_mapped_cluster(inode, sector, last_block, mapped_blocks,
				      phys);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/fat/cache.c
	3	*
	4	* Written 1992,1993 by Werner Almesberger
	5	*
	6	* Mar 1999. AV. Changed cache, so that it uses the starting cluster instead
	7	* of inode number.
	8	* May 1999. AV. Fixed the bogosity with FAT32 (read "FAT28"). Fscking lusers.
	9	*/
	10
5a0e3ad6	11	#include <linux/slab.h>
9e975dae	12	#include "fat.h"
1da177e4 LT	13
	14	/* this must be > 0. */
	15	#define FAT_MAX_CACHE 8
	16
	17	struct fat_cache {
	18	struct list_head cache_list;
	19	int nr_contig; /* number of contiguous clusters */
	20	int fcluster; /* cluster number in the file. */
	21	int dcluster; /* cluster number on disk. */
	22	};
	23
	24	struct fat_cache_id {
	25	unsigned int id;
	26	int nr_contig;
	27	int fcluster;
	28	int dcluster;
	29	};
	30
	31	static inline int fat_max_cache(struct inode *inode)
	32	{
	33	return FAT_MAX_CACHE;
	34	}
	35
e18b890b	36	static struct kmem_cache *fat_cache_cachep;
1da177e4	37
51cc5068	38	static void init_once(void *foo)
1da177e4 LT	39	{
	40	struct fat_cache cache = (struct fat_cache )foo;
	41
a35afb83	42	INIT_LIST_HEAD(&cache->cache_list);
1da177e4 LT	43	}
	44
	45	int __init fat_cache_init(void)
	46	{
	47	fat_cache_cachep = kmem_cache_create("fat_cache",
	48	sizeof(struct fat_cache),
4b6a9316	49	0, SLAB_RECLAIM_ACCOUNT\|SLAB_MEM_SPREAD,
20c2df83	50	init_once);
1da177e4 LT	51	if (fat_cache_cachep == NULL)
	52	return -ENOMEM;
	53	return 0;
	54	}
	55
ef6689ef	56	void fat_cache_destroy(void)
1da177e4	57	{
1a1d92c1	58	kmem_cache_destroy(fat_cache_cachep);
1da177e4 LT	59	}
	60
	61	static inline struct fat_cache fat_cache_alloc(struct inode inode)
	62	{
8f593427	63	return kmem_cache_alloc(fat_cache_cachep, GFP_NOFS);
1da177e4 LT	64	}
	65
	66	static inline void fat_cache_free(struct fat_cache *cache)
	67	{
	68	BUG_ON(!list_empty(&cache->cache_list));
	69	kmem_cache_free(fat_cache_cachep, cache);
	70	}
	71
	72	static inline void fat_cache_update_lru(struct inode *inode,
	73	struct fat_cache *cache)
	74	{
	75	if (MSDOS_I(inode)->cache_lru.next != &cache->cache_list)
	76	list_move(&cache->cache_list, &MSDOS_I(inode)->cache_lru);
	77	}
	78
	79	static int fat_cache_lookup(struct inode *inode, int fclus,
	80	struct fat_cache_id *cid,
	81	int cached_fclus, int cached_dclus)
	82	{
	83	static struct fat_cache nohit = { .fcluster = 0, };
	84
	85	struct fat_cache hit = &nohit, p;
	86	int offset = -1;
	87
	88	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
	89	list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) {
	90	/* Find the cache of "fclus" or nearest cache. */
	91	if (p->fcluster <= fclus && hit->fcluster < p->fcluster) {
	92	hit = p;
	93	if ((hit->fcluster + hit->nr_contig) < fclus) {
	94	offset = hit->nr_contig;
	95	} else {
	96	offset = fclus - hit->fcluster;
	97	break;
	98	}
	99	}
	100	}
	101	if (hit != &nohit) {
	102	fat_cache_update_lru(inode, hit);
	103
	104	cid->id = MSDOS_I(inode)->cache_valid_id;
	105	cid->nr_contig = hit->nr_contig;
	106	cid->fcluster = hit->fcluster;
	107	cid->dcluster = hit->dcluster;
	108	*cached_fclus = cid->fcluster + offset;
	109	*cached_dclus = cid->dcluster + offset;
	110	}
	111	spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
	112
	113	return offset;
	114	}
	115
	116	static struct fat_cache fat_cache_merge(struct inode inode,
	117	struct fat_cache_id *new)
	118	{
	119	struct fat_cache *p;
	120
	121	list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) {
	122	/* Find the same part as "new" in cluster-chain. */
	123	if (p->fcluster == new->fcluster) {
	124	BUG_ON(p->dcluster != new->dcluster);
	125	if (new->nr_contig > p->nr_contig)
	126	p->nr_contig = new->nr_contig;
	127	return p;
128	}
129	}
130	return NULL;
131	}
132
133	static void fat_cache_add(struct inode inode, struct fat_cache_id new)
134	{
135	struct fat_cache cache, tmp;
136
137	if (new->fcluster == -1) /* dummy cache */
138	return;
139
140	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
141	if (new->id != FAT_CACHE_VALID &&
142	new->id != MSDOS_I(inode)->cache_valid_id)
143	goto out; /* this cache was invalidated */
144
145	cache = fat_cache_merge(inode, new);
146	if (cache == NULL) {
147	if (MSDOS_I(inode)->nr_caches < fat_max_cache(inode)) {
148	MSDOS_I(inode)->nr_caches++;
149	spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
150
151	tmp = fat_cache_alloc(inode);
70030929 OH	152	if (!tmp) {
	153	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
	154	MSDOS_I(inode)->nr_caches--;
	155	spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
	156	return;
	157	}
	158
1da177e4 LT	159	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
	160	cache = fat_cache_merge(inode, new);
	161	if (cache != NULL) {
	162	MSDOS_I(inode)->nr_caches--;
	163	fat_cache_free(tmp);
	164	goto out_update_lru;
	165	}
	166	cache = tmp;
	167	} else {
	168	struct list_head *p = MSDOS_I(inode)->cache_lru.prev;
	169	cache = list_entry(p, struct fat_cache, cache_list);
	170	}
	171	cache->fcluster = new->fcluster;
	172	cache->dcluster = new->dcluster;
	173	cache->nr_contig = new->nr_contig;
	174	}
	175	out_update_lru:
	176	fat_cache_update_lru(inode, cache);
	177	out:
	178	spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
	179	}
	180
	181	/*
	182	* Cache invalidation occurs rarely, thus the LRU chain is not updated. It
	183	* fixes itself after a while.
	184	*/
	185	static void __fat_cache_inval_inode(struct inode *inode)
	186	{
	187	struct msdos_inode_info *i = MSDOS_I(inode);
	188	struct fat_cache *cache;
	189
	190	while (!list_empty(&i->cache_lru)) {
c9051829 CJB	191	cache = list_entry(i->cache_lru.next,
c9051829 CJB	192	struct fat_cache, cache_list);
1da177e4 LT	193	list_del_init(&cache->cache_list);
	194	i->nr_caches--;
	195	fat_cache_free(cache);
	196	}
	197	/* Update. The copy of caches before this id is discarded. */
	198	i->cache_valid_id++;
	199	if (i->cache_valid_id == FAT_CACHE_VALID)
	200	i->cache_valid_id++;
	201	}
	202
	203	void fat_cache_inval_inode(struct inode *inode)
	204	{
	205	spin_lock(&MSDOS_I(inode)->cache_lru_lock);
	206	__fat_cache_inval_inode(inode);
	207	spin_unlock(&MSDOS_I(inode)->cache_lru_lock);
	208	}
	209
	210	static inline int cache_contiguous(struct fat_cache_id *cid, int dclus)
	211	{
	212	cid->nr_contig++;
	213	return ((cid->dcluster + cid->nr_contig) == dclus);
	214	}
	215
	216	static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus)
	217	{
	218	cid->id = FAT_CACHE_VALID;
	219	cid->fcluster = fclus;
	220	cid->dcluster = dclus;
	221	cid->nr_contig = 0;
	222	}
	223
	224	int fat_get_cluster(struct inode inode, int cluster, int fclus, int *dclus)
	225	{
	226	struct super_block *sb = inode->i_sb;
	227	const int limit = sb->s_maxbytes >> MSDOS_SB(sb)->cluster_bits;
	228	struct fat_entry fatent;
	229	struct fat_cache_id cid;
	230	int nr;
	231
	232	BUG_ON(MSDOS_I(inode)->i_start == 0);
	233
	234	*fclus = 0;
	235	*dclus = MSDOS_I(inode)->i_start;
	236	if (cluster == 0)
	237	return 0;
	238
	239	if (fat_cache_lookup(inode, cluster, &cid, fclus, dclus) < 0) {
	240	/*
	241	* dummy, always not contiguous
	242	* This is reinitialized by cache_init(), later.
	243	*/
	244	cache_init(&cid, -1, -1);
	245	}
	246
	247	fatent_init(&fatent);
	248	while (*fclus < cluster) {
	249	/* prevent the infinite loop of cluster chain */
	250	if (*fclus > limit) {
aaa04b48 OH	251	fat_fs_error_ratelimit(sb,
	252	"%s: detected the cluster chain loop"
	253	" (i_pos %lld)", __func__,
	254	MSDOS_I(inode)->i_pos);
1da177e4 LT	255	nr = -EIO;
	256	goto out;
	257	}
	258
	259	nr = fat_ent_read(inode, &fatent, *dclus);
	260	if (nr < 0)
	261	goto out;
	262	else if (nr == FAT_ENT_FREE) {
c9051829 CJB	263	fat_fs_error_ratelimit(sb,
	264	"%s: invalid cluster chain (i_pos %lld)",
	265	__func__,
	266	MSDOS_I(inode)->i_pos);
1da177e4 LT	267	nr = -EIO;
	268	goto out;
	269	} else if (nr == FAT_ENT_EOF) {
	270	fat_cache_add(inode, &cid);
	271	goto out;
	272	}
	273	(*fclus)++;
	274	*dclus = nr;
	275	if (!cache_contiguous(&cid, *dclus))
	276	cache_init(&cid, fclus, dclus);
	277	}
	278	nr = 0;
	279	fat_cache_add(inode, &cid);
	280	out:
	281	fatent_brelse(&fatent);
	282	return nr;
	283	}
	284
	285	static int fat_bmap_cluster(struct inode *inode, int cluster)
	286	{
	287	struct super_block *sb = inode->i_sb;
	288	int ret, fclus, dclus;
	289
	290	if (MSDOS_I(inode)->i_start == 0)
	291	return 0;
	292
	293	ret = fat_get_cluster(inode, cluster, &fclus, &dclus);
	294	if (ret < 0)
	295	return ret;
	296	else if (ret == FAT_ENT_EOF) {
85c78591	297	fat_fs_error(sb, "%s: request beyond EOF (i_pos %lld)",
8e24eea7	298	__func__, MSDOS_I(inode)->i_pos);
1da177e4 LT	299	return -EIO;
	300	}
	301	return dclus;
	302	}
	303
16fab201 NJ	304	int fat_get_mapped_cluster(struct inode *inode, sector_t sector,
	305	sector_t last_block,
	306	unsigned long mapped_blocks, sector_t bmap)
1da177e4 LT	307	{
	308	struct super_block *sb = inode->i_sb;
	309	struct msdos_sb_info *sbi = MSDOS_SB(sb);
16fab201 NJ	310	int cluster, offset;
	311
	312	cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
	313	offset = sector & (sbi->sec_per_clus - 1);
	314	cluster = fat_bmap_cluster(inode, cluster);
	315	if (cluster < 0)
	316	return cluster;
	317	else if (cluster) {
	318	*bmap = fat_clus_to_blknr(sbi, cluster) + offset;
	319	*mapped_blocks = sbi->sec_per_clus - offset;
	320	if (*mapped_blocks > last_block - sector)
	321	*mapped_blocks = last_block - sector;
	322	}
	323
	324	return 0;
	325	}
	326
	327	static int is_exceed_eof(struct inode *inode, sector_t sector,
	328	sector_t *last_block, int create)
	329	{
	330	struct super_block *sb = inode->i_sb;
2bdf67eb OH	331	const unsigned long blocksize = sb->s_blocksize;
2bdf67eb OH	332	const unsigned char blocksize_bits = sb->s_blocksize_bits;
16fab201 NJ	333
	334	*last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
	335	if (sector >= *last_block) {
	336	if (!create)
	337	return 1;
	338
	339	/*
	340	* ->mmu_private can access on only allocation path.
	341	* (caller must hold ->i_mutex)
	342	*/
	343	*last_block = (MSDOS_I(inode)->mmu_private + (blocksize - 1))
	344	>> blocksize_bits;
	345	if (sector >= *last_block)
	346	return 1;
	347	}
	348
	349	return 0;
	350	}
	351
	352	int fat_bmap(struct inode inode, sector_t sector, sector_t phys,
	353	unsigned long *mapped_blocks, int create, bool from_bmap)
	354	{
	355	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1da177e4	356	sector_t last_block;
1da177e4 LT	357
1da177e4 LT	358	*phys = 0;
e5174baa	359	*mapped_blocks = 0;
1da177e4	360	if ((sbi->fat_bits != 32) && (inode->i_ino == MSDOS_ROOT_INO)) {
e5174baa	361	if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits)) {
1da177e4	362	*phys = sector + sbi->dir_start;
e5174baa OH	363	*mapped_blocks = 1;
e5174baa OH	364	}
1da177e4 LT	365	return 0;
1da177e4 LT	366	}
2bdf67eb	367
16fab201 NJ	368	if (!from_bmap) {
16fab201 NJ	369	if (is_exceed_eof(inode, sector, &last_block, create))
2bdf67eb	370	return 0;
16fab201 NJ	371	} else {
	372	last_block = inode->i_blocks >>
	373	(inode->i_sb->s_blocksize_bits - 9);
2bdf67eb OH	374	if (sector >= last_block)
	375	return 0;
	376	}
1da177e4	377
16fab201 NJ	378	return fat_get_mapped_cluster(inode, sector, last_block, mapped_blocks,
16fab201 NJ	379	phys);
1da177e4	380	}