diff options
| author | Imran Khan <imran.f.khan@oracle.com> | 2023-03-09 22:09:31 +1100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-29 12:23:45 +0200 |
| commit | c9f2dfb7b59e5a6db054f821a6e1a6db8fa57d64 (patch) | |
| tree | 05c655fea0c99066e83b7593479ccbc6d9e10389 /fs/kernfs | |
| parent | 9caf696142252a466fb89e629d0eddcdced027b0 (diff) | |
kernfs: Use a per-fs rwsem to protect per-fs list of kernfs_super_info.
Right now per-fs kernfs_rwsem protects list of kernfs_super_info instances
for a kernfs_root. Since kernfs_rwsem is used to synchronize several other
operations across kernfs and since most of these operations don't impact
kernfs_super_info, we can use a separate per-fs rwsem to synchronize access
to list of kernfs_super_info.
This helps in reducing contention around kernfs_rwsem and also allows
operations that change/access list of kernfs_super_info to proceed without
contending for kernfs_rwsem.
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20230309110932.2889010-3-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs')
| -rw-r--r-- | fs/kernfs/dir.c | 1 | ||||
| -rw-r--r-- | fs/kernfs/file.c | 4 | ||||
| -rw-r--r-- | fs/kernfs/kernfs-internal.h | 1 | ||||
| -rw-r--r-- | fs/kernfs/mount.c | 8 |
4 files changed, 8 insertions, 6 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 953b2717c60e..2cdb8516e528 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -944,6 +944,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, idr_init(&root->ino_idr); init_rwsem(&root->kernfs_rwsem); init_rwsem(&root->kernfs_iattr_rwsem); + init_rwsem(&root->kernfs_supers_rwsem); INIT_LIST_HEAD(&root->supers); /* diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index e4a50e4ff0d2..40c4661f15b7 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -922,8 +922,8 @@ repeat: root = kernfs_root(kn); /* kick fsnotify */ - down_write(&root->kernfs_rwsem); + down_read(&root->kernfs_supers_rwsem); list_for_each_entry(info, &kernfs_root(kn)->supers, node) { struct kernfs_node *parent; struct inode *p_inode = NULL; @@ -960,7 +960,7 @@ repeat: iput(inode); } - up_write(&root->kernfs_rwsem); + up_read(&root->kernfs_supers_rwsem); kernfs_put(kn); goto repeat; } diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index 3297093c920d..a9b854cdfdb5 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -48,6 +48,7 @@ struct kernfs_root { wait_queue_head_t deactivate_waitq; struct rw_semaphore kernfs_rwsem; struct rw_semaphore kernfs_iattr_rwsem; + struct rw_semaphore kernfs_supers_rwsem; }; /* +1 to avoid triggering overflow warning when negating it */ diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index e08e8d999807..d49606accb07 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -351,9 +351,9 @@ int kernfs_get_tree(struct fs_context *fc) } sb->s_flags |= SB_ACTIVE; - down_write(&root->kernfs_rwsem); + down_write(&root->kernfs_supers_rwsem); list_add(&info->node, &info->root->supers); - up_write(&root->kernfs_rwsem); + up_write(&root->kernfs_supers_rwsem); } fc->root = dget(sb->s_root); @@ -380,9 +380,9 @@ void kernfs_kill_sb(struct super_block *sb) struct kernfs_super_info *info = kernfs_info(sb); struct kernfs_root *root = info->root; - down_write(&root->kernfs_rwsem); + down_write(&root->kernfs_supers_rwsem); list_del(&info->node); - up_write(&root->kernfs_rwsem); + up_write(&root->kernfs_supers_rwsem); /* * Remove the superblock from fs_supers/s_instances |