HPFS: Introduce a global mutex and lock it on every callback from VFS.
Introduce a global mutex and lock it on every callback from VFS.
Performance doesn't matter, reviewing the whole code for locking correctness
would be too complicated, so simply lock it all.
Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/hpfs/hpfs_fn.h b/fs/hpfs/hpfs_fn.h
index c15adbc..89a4714 100644
--- a/fs/hpfs/hpfs_fn.h
+++ b/fs/hpfs/hpfs_fn.h
@@ -63,6 +63,7 @@
};
struct hpfs_sb_info {
+ struct mutex hpfs_mutex; /* global hpfs lock */
ino_t sb_root; /* inode number of root dir */
unsigned sb_fs_size; /* file system size, sectors */
unsigned sb_bitmaps; /* sector number of bitmap list */
@@ -346,21 +347,26 @@
/*
* Locking:
*
- * hpfs_lock() is a leftover from the big kernel lock.
- * Right now, these functions are empty and only left
- * for documentation purposes. The file system no longer
- * works on SMP systems, so the lock is not needed
- * any more.
+ * hpfs_lock() locks the whole filesystem. It must be taken
+ * on any method called by the VFS.
*
- * If someone is interested in making it work again, this
- * would be the place to start by adding a per-superblock
- * mutex and fixing all the bugs and performance issues
- * caused by that.
+ * We don't do any per-file locking anymore, it is hard to
+ * review and HPFS is not performance-sensitive anyway.
*/
static inline void hpfs_lock(struct super_block *s)
{
+ struct hpfs_sb_info *sbi = hpfs_sb(s);
+ mutex_lock(&sbi->hpfs_mutex);
}
static inline void hpfs_unlock(struct super_block *s)
{
+ struct hpfs_sb_info *sbi = hpfs_sb(s);
+ mutex_unlock(&sbi->hpfs_mutex);
+}
+
+static inline void hpfs_lock_assert(struct super_block *s)
+{
+ struct hpfs_sb_info *sbi = hpfs_sb(s);
+ WARN_ON(!mutex_is_locked(&sbi->hpfs_mutex));
}