exfat: introduce bitmap_lock for cluster bitmap access

s_lock which is for protecting concurrent access of file operations is
too huge for cluster bitmap protection, so introduce a new bitmap_lock
to narrow the lock range if only need to access cluster bitmap.

Signed-off-by: Hyeongseok Kim <hyeongseok@gmail.com>
Acked-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index fa21421..e05e0a3 100644 (file)
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -238,6 +238,7 @@ struct exfat_sb_info {
        unsigned int used_clusters; /* number of used clusters */
 
        struct mutex s_lock; /* superblock lock */
+       struct mutex bitmap_lock; /* bitmap lock */
        struct exfat_mount_options options;
        struct nls_table *nls_io; /* Charset used for input and display */
        struct ratelimit_state ratelimit;

diff --git a/fs/exfat/fatent.c b/fs/exfat/fatent.c
index 7b2e8af..fd6c7fd 100644 (file)
--- a/fs/exfat/fatent.c
+++ b/fs/exfat/fatent.c
@@ -151,13 +151,14 @@ int exfat_chain_cont_cluster(struct super_block *sb, unsigned int chain,
        return 0;
 }
 
-int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
+/* This function must be called with bitmap_lock held */
+static int __exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
 {
-       unsigned int num_clusters = 0;
-       unsigned int clu;
        struct super_block *sb = inode->i_sb;
        struct exfat_sb_info *sbi = EXFAT_SB(sb);
        int cur_cmap_i, next_cmap_i;
+       unsigned int num_clusters = 0;
+       unsigned int clu;
 
        /* invalid cluster number */
        if (p_chain->dir == EXFAT_FREE_CLUSTER ||
@@ -230,6 +231,17 @@ dec_used_clus:
        return 0;
 }
 
+int exfat_free_cluster(struct inode *inode, struct exfat_chain *p_chain)
+{
+       int ret = 0;
+
+       mutex_lock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
+       ret = __exfat_free_cluster(inode, p_chain);
+       mutex_unlock(&EXFAT_SB(inode->i_sb)->bitmap_lock);
+
+       return ret;
+}
+
 int exfat_find_last_cluster(struct super_block *sb, struct exfat_chain *p_chain,
                unsigned int *ret_clu)
 {
@@ -328,6 +340,8 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
        if (num_alloc > total_cnt - sbi->used_clusters)
                return -ENOSPC;
 
+       mutex_lock(&sbi->bitmap_lock);
+
        hint_clu = p_chain->dir;
        /* find new cluster */
        if (hint_clu == EXFAT_EOF_CLUSTER) {
@@ -338,8 +352,10 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
                }
 
                hint_clu = exfat_find_free_bitmap(sb, sbi->clu_srch_ptr);
-               if (hint_clu == EXFAT_EOF_CLUSTER)
-                       return -ENOSPC;
+               if (hint_clu == EXFAT_EOF_CLUSTER) {
+                       ret = -ENOSPC;
+                       goto unlock;
+               }
        }
 
        /* check cluster validation */
@@ -349,8 +365,10 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
                hint_clu = EXFAT_FIRST_CLUSTER;
                if (p_chain->flags == ALLOC_NO_FAT_CHAIN) {
                        if (exfat_chain_cont_cluster(sb, p_chain->dir,
-                                       num_clusters))
-                               return -EIO;
+                                       num_clusters)) {
+                               ret = -EIO;
+                               goto unlock;
+                       }
                        p_chain->flags = ALLOC_FAT_CHAIN;
                }
        }
@@ -400,6 +418,7 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
                        sbi->used_clusters += num_clusters;
 
                        p_chain->size += num_clusters;
+                       mutex_unlock(&sbi->bitmap_lock);
                        return 0;
                }
 
@@ -419,7 +438,9 @@ int exfat_alloc_cluster(struct inode *inode, unsigned int num_alloc,
        }
 free_cluster:
        if (num_clusters)
-               exfat_free_cluster(inode, p_chain);
+               __exfat_free_cluster(inode, p_chain);
+unlock:
+       mutex_unlock(&sbi->bitmap_lock);
        return ret;
 }
 

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index c6d8d2e..d38d17a 100644 (file)
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -752,6 +752,7 @@ static int exfat_init_fs_context(struct fs_context *fc)
                return -ENOMEM;
 
        mutex_init(&sbi->s_lock);
+       mutex_init(&sbi->bitmap_lock);
        ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
                        DEFAULT_RATELIMIT_BURST);