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fat: rcu-delay unloading nls and freeing sbi

makes ->d_hash() and ->d_compare() safety in RCU mode independent
from vfsmount_lock.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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commit cac45b062c67f86dc1d91d675128838773523243 1 parent 2e32cf5
Al Viro authored
Showing with 12 additions and 8 deletions.
  1. +1 −0  fs/fat/fat.h
  2. +11 −8 fs/fat/inode.c
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1  fs/fat/fat.h
@@ -102,6 +102,7 @@ struct msdos_sb_info {
struct hlist_head dir_hashtable[FAT_HASH_SIZE];
unsigned int dirty; /* fs state before mount */
+ struct rcu_head rcu;
};
#define FAT_CACHE_VALID 0 /* special case for valid cache */
View
19 fs/fat/inode.c
@@ -548,6 +548,16 @@ static void fat_set_state(struct super_block *sb,
brelse(bh);
}
+static void delayed_free(struct rcu_head *p)
+{
+ struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
+ unload_nls(sbi->nls_disk);
+ unload_nls(sbi->nls_io);
+ if (sbi->options.iocharset != fat_default_iocharset)
+ kfree(sbi->options.iocharset);
+ kfree(sbi);
+}
+
static void fat_put_super(struct super_block *sb)
{
struct msdos_sb_info *sbi = MSDOS_SB(sb);
@@ -557,14 +567,7 @@ static void fat_put_super(struct super_block *sb)
iput(sbi->fsinfo_inode);
iput(sbi->fat_inode);
- unload_nls(sbi->nls_disk);
- unload_nls(sbi->nls_io);
-
- if (sbi->options.iocharset != fat_default_iocharset)
- kfree(sbi->options.iocharset);
-
- sb->s_fs_info = NULL;
- kfree(sbi);
+ call_rcu(&sbi->rcu, delayed_free);
}
static struct kmem_cache *fat_inode_cachep;
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