diff options
Diffstat (limited to 'store/works/life/operating-system-course-design/0001-crupesteam-fat-patch.patch')
| -rw-r--r-- | store/works/life/operating-system-course-design/0001-crupesteam-fat-patch.patch | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/store/works/life/operating-system-course-design/0001-crupesteam-fat-patch.patch b/store/works/life/operating-system-course-design/0001-crupesteam-fat-patch.patch new file mode 100644 index 0000000..9f23ebb --- /dev/null +++ b/store/works/life/operating-system-course-design/0001-crupesteam-fat-patch.patch @@ -0,0 +1,163 @@ +From e88345bbb9a4027033254933ee2e1cad9feab6d6 Mon Sep 17 00:00:00 2001 +From: crupest <crupest@outlook.com> +Date: Thu, 24 Jun 2021 16:00:04 +0800 +Subject: [PATCH] crupesteam fat patch. + +--- + fs/fat/cache.c | 64 ++++++++++++++++++++++++++++++++++++++++++++------ + 1 file changed, 57 insertions(+), 7 deletions(-) + +diff --git a/fs/fat/cache.c b/fs/fat/cache.c +index 738e427e2d21..4f32bfee6d27 100644 +--- a/fs/fat/cache.c ++++ b/fs/fat/cache.c +@@ -15,11 +15,15 @@ + /* this must be > 0. */ + #define FAT_MAX_CACHE 8 + ++#define FAT_CACHE_PREV_CLUSTER_COUNT 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. */ ++ int prev_clusters_count; ++ int prev_clusters[FAT_CACHE_PREV_CLUSTER_COUNT]; + }; + + struct fat_cache_id { +@@ -27,6 +31,8 @@ struct fat_cache_id { + int nr_contig; + int fcluster; + int dcluster; ++ int prev_clusters_count; ++ int prev_clusters[FAT_CACHE_PREV_CLUSTER_COUNT]; + }; + + static inline int fat_max_cache(struct inode *inode) +@@ -84,10 +90,17 @@ static int fat_cache_lookup(struct inode *inode, int fclus, + static struct fat_cache nohit = { .fcluster = 0, }; + + struct fat_cache *hit = &nohit, *p; +- int offset = -1; ++ int offset = INT_MIN; + + spin_lock(&MSDOS_I(inode)->cache_lru_lock); + list_for_each_entry(p, &MSDOS_I(inode)->cache_lru, cache_list) { ++ if (p->fcluster > fclus && ++ p->fcluster - p->prev_clusters_count <= fclus) { ++ hit = p; ++ offset = fclus - hit->fcluster; ++ break; ++ } ++ + /* Find the cache of "fclus" or nearest cache. */ + if (p->fcluster <= fclus && hit->fcluster < p->fcluster) { + hit = p; +@@ -107,7 +120,11 @@ static int fat_cache_lookup(struct inode *inode, int fclus, + cid->fcluster = hit->fcluster; + cid->dcluster = hit->dcluster; + *cached_fclus = cid->fcluster + offset; +- *cached_dclus = cid->dcluster + offset; ++ ++ if (offset < 0) ++ *cached_dclus = hit->prev_clusters[hit->prev_clusters_count + offset]; ++ else ++ *cached_dclus = cid->dcluster + offset; + } + spin_unlock(&MSDOS_I(inode)->cache_lru_lock); + +@@ -145,6 +162,8 @@ static void fat_cache_add(struct inode *inode, struct fat_cache_id *new) + + cache = fat_cache_merge(inode, new); + if (cache == NULL) { ++ int i; ++ + if (MSDOS_I(inode)->nr_caches < fat_max_cache(inode)) { + MSDOS_I(inode)->nr_caches++; + spin_unlock(&MSDOS_I(inode)->cache_lru_lock); +@@ -172,6 +191,10 @@ static void fat_cache_add(struct inode *inode, struct fat_cache_id *new) + cache->fcluster = new->fcluster; + cache->dcluster = new->dcluster; + cache->nr_contig = new->nr_contig; ++ cache->prev_clusters_count = new->prev_clusters_count; ++ for (i = 0; i < new->prev_clusters_count; i++) { ++ cache->prev_clusters[i] = new->prev_clusters[i]; ++ } + } + out_update_lru: + fat_cache_update_lru(inode, cache); +@@ -220,6 +243,7 @@ static inline void cache_init(struct fat_cache_id *cid, int fclus, int dclus) + cid->fcluster = fclus; + cid->dcluster = dclus; + cid->nr_contig = 0; ++ cid->prev_clusters_count = 0; + } + + int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) +@@ -230,6 +254,10 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) + struct fat_entry fatent; + struct fat_cache_id cid; + int nr; ++ int offset; ++ int prev_cluster[FAT_CACHE_PREV_CLUSTER_COUNT]; ++ int prev_cluster_current = 0; ++ int prev_cluster_count = 0; + + BUG_ON(MSDOS_I(inode)->i_start == 0); + +@@ -244,12 +272,13 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) + 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. +- */ ++ offset = fat_cache_lookup(inode, cluster, &cid, fclus, dclus); ++ ++ if (offset == INT_MIN) { + cache_init(&cid, -1, -1); ++ } else if (offset < 0) { ++ nr = 0; ++ goto out; + } + + fatent_init(&fatent); +@@ -278,10 +307,31 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus) + } + (*fclus)++; + *dclus = nr; ++ ++ prev_cluster[prev_cluster_current++] = *dclus; ++ if (prev_cluster_count < FAT_CACHE_PREV_CLUSTER_COUNT) { ++ prev_cluster_count++; ++ } ++ prev_cluster_current %= FAT_CACHE_PREV_CLUSTER_COUNT; ++ + if (!cache_contiguous(&cid, *dclus)) + cache_init(&cid, *fclus, *dclus); + } + nr = 0; ++ ++ if (cid.nr_contig + 1 < FAT_CACHE_PREV_CLUSTER_COUNT) { ++ int i; ++ int count = prev_cluster_count - cid.nr_contig - 1; ++ int start = ((prev_cluster_current - prev_cluster_count) ++ + FAT_CACHE_PREV_CLUSTER_COUNT) % FAT_CACHE_PREV_CLUSTER_COUNT; ++ ++ cid.prev_clusters_count = count; ++ ++ for (i = 0; i < count; i++) { ++ cid.prev_clusters[i] = prev_cluster[(start + i) % FAT_CACHE_PREV_CLUSTER_COUNT]; ++ } ++ } ++ + fat_cache_add(inode, &cid); + out: + fatent_brelse(&fatent); +-- +2.32.0 + |