erofs: introduce multipage per-CPU buffers

To deal the with the cases which inplace decompression is infeasible
for some inplace I/O. Per-CPU buffers was introduced to get rid of page
allocation latency and thrash for low-latency decompression algorithms
such as lz4.

For the big pcluster feature, introduce multipage per-CPU buffers to
keep such inplace I/O pclusters temporarily as well but note that
per-CPU pages are just consecutive virtually.

When a new big pcluster fs is mounted, its max pclustersize will be
read and per-CPU buffers can be growed if needed. Shrinking adjustable
per-CPU buffers is more complex (because we don't know if such size
is still be used), so currently just release them all when unloading.

Link: https://lore.kernel.org/r/20210409190630.19569-1-xiang@kernel.org
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index b641658e772f..bbf3bbd908e0 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -655,6 +655,7 @@ static int __init erofs_module_init(void)
 	if (err)
 		goto shrinker_err;
 
+	erofs_pcpubuf_init();
 	err = z_erofs_init_zip_subsystem();
 	if (err)
 		goto zip_err;
@@ -684,6 +685,7 @@ static void __exit erofs_module_exit(void)
 	/* Ensure all RCU free inodes are safe before cache is destroyed. */
 	rcu_barrier();
 	kmem_cache_destroy(erofs_inode_cachep);
+	erofs_pcpubuf_exit();
 }
 
 /* get filesystem statistics */