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affs: Replace binary semaphores with mutexes 

At a slight footprint cost (24 vs 32 bytes), mutexes are more optimal
than semaphores; it's also a nicer interface for mutual exclusion,
which is why they are encouraged over binary semaphores, when possible.

For both i_link_lock and i_ext_lock (and hence i_hash_lock which I
annotated for the hash lock mapping hackery for lockdep), their semantics
imply traditional lock ownership; that is, the lock owner is the same for
both lock/unlock operations and does not run in irq context. Therefore
it is safe to convert.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Davidlohr Bueso 2019-10-27 15:01:43 -07:00 committed by David Sterba
parent af42d3466b
commit 6060c07d47
2 changed files with 10 additions and 10 deletions
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16
fs/affs/affs.h
View File

@ -43,8 +43,8 @@ struct affs_ext_key {
*/
struct affs_inode_info {
atomic_t i_opencnt;
struct semaphore i_link_lock; /* Protects internal inode access. */
struct semaphore i_ext_lock; /* Protects internal inode access. */
struct mutex i_link_lock; /* Protects internal inode access. */
struct mutex i_ext_lock; /* Protects internal inode access. */
#define i_hash_lock i_ext_lock
u32 i_blkcnt; /* block count */
u32 i_extcnt; /* extended block count */
@ -293,30 +293,30 @@ affs_adjust_bitmapchecksum(struct buffer_head *bh, u32 val)
static inline void
affs_lock_link(struct inode *inode)
{
down(&AFFS_I(inode)->i_link_lock);
mutex_lock(&AFFS_I(inode)->i_link_lock);
}
static inline void
affs_unlock_link(struct inode *inode)
{
up(&AFFS_I(inode)->i_link_lock);
mutex_unlock(&AFFS_I(inode)->i_link_lock);
}
static inline void
affs_lock_dir(struct inode *inode)
{
down(&AFFS_I(inode)->i_hash_lock);
mutex_lock_nested(&AFFS_I(inode)->i_hash_lock, SINGLE_DEPTH_NESTING);
}
static inline void
affs_unlock_dir(struct inode *inode)
{
up(&AFFS_I(inode)->i_hash_lock);
mutex_unlock(&AFFS_I(inode)->i_hash_lock);
}
static inline void
affs_lock_ext(struct inode *inode)
{
down(&AFFS_I(inode)->i_ext_lock);
mutex_lock(&AFFS_I(inode)->i_ext_lock);
}
static inline void
affs_unlock_ext(struct inode *inode)
{
up(&AFFS_I(inode)->i_ext_lock);
mutex_unlock(&AFFS_I(inode)->i_ext_lock);
}

4
fs/affs/super.c
View File

@ -121,8 +121,8 @@ static void init_once(void *foo)
{
struct affs_inode_info *ei = (struct affs_inode_info *) foo;
sema_init(&ei->i_link_lock, 1);
sema_init(&ei->i_ext_lock, 1);
mutex_init(&ei->i_link_lock);
mutex_init(&ei->i_ext_lock);
inode_init_once(&ei->vfs_inode);
}