erofs: force inplace I/O under low memory scenario
Try to forcely switch to inplace I/O under low memory scenario in
order to avoid direct memory reclaim due to cached page allocation.
Link: https://lore.kernel.org/r/20201209123717.12430-1-hsiangkao@aol.com
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index 4dadde1..aea129d 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -28,11 +28,13 @@ struct z_erofs_decompress_req {
/* some special page->private (unsigned long, see below) */
#define Z_EROFS_SHORTLIVED_PAGE (-1UL << 2)
+#define Z_EROFS_PREALLOCATED_PAGE (-2UL << 2)
/*
* For all pages in a pcluster, page->private should be one of
* Type Last 2bits page->private
* short-lived page 00 Z_EROFS_SHORTLIVED_PAGE
+ * preallocated page (tryalloc) 00 Z_EROFS_PREALLOCATED_PAGE
* cached/managed page 00 pointer to z_erofs_pcluster
* online page (file-backed, 01/10/11 sub-index << 2 | count
* some pages can be used for inplace I/O)
@@ -40,6 +42,7 @@ struct z_erofs_decompress_req {
* page->mapping should be one of
* Type page->mapping
* short-lived page NULL
+ * preallocated page NULL
* cached/managed page non-NULL or NULL (invalidated/truncated page)
* online page non-NULL
*
