[PATCH 20/21] erofs: kill use_vmap module parameter

[Gao Xiang]

From: Gao Xiang <gaoxiang25 at huawei.com>

As Christoph said [1],
"vm_map_ram is supposed to generally behave better.  So if
it doesn't please report that that to the arch maintainer
and linux-mm so that they can look into the issue.  Having
user make choices of deep down kernel internals is just
a horrible interface.

Please talk to maintainers of other bits of the kernel
if you see issues and / or need enhancements. "

Let's redo the previous conclusion and kill the vmap
approach.

[1] https://lore.kernel.org/r/20190830165533.GA10909@infradead.org/
Reported-by: Christoph Hellwig <hch at infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25 at huawei.com>
---
 Documentation/filesystems/erofs.txt |  4 ----
 fs/erofs/decompressor.c             | 12 +-----------
 2 files changed, 1 insertion(+), 15 deletions(-)

diff --git a/Documentation/filesystems/erofs.txt b/Documentation/filesystems/erofs.txt
index c3b5f603b2b6..b0c085326e2e 100644
--- a/Documentation/filesystems/erofs.txt
+++ b/Documentation/filesystems/erofs.txt
@@ -67,10 +67,6 @@ cache_strategy=%s      Select a strategy for cached decompression from now on:
                                    It still does in-place I/O decompression
                                    for the rest compressed physical clusters.
 
-Module parameters
-=================
-use_vmap=[0|1]         Use vmap() instead of vm_map_ram() (default 0).
-
 On-disk details
 ===============
 
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index bb2944c96c89..af273d89e62c 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -28,10 +28,6 @@ struct z_erofs_decompressor {
 	char *name;
 };
 
-static bool use_vmap;
-module_param(use_vmap, bool, 0444);
-MODULE_PARM_DESC(use_vmap, "Use vmap() instead of vm_map_ram() (default 0)");
-
 static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
 					 struct list_head *pagepool)
 {
@@ -224,9 +220,6 @@ static void *erofs_vmap(struct page **pages, unsigned int count)
 {
 	int i = 0;
 
-	if (use_vmap)
-		return vmap(pages, count, VM_MAP, PAGE_KERNEL);
-
 	while (1) {
 		void *addr = vm_map_ram(pages, count, -1, PAGE_KERNEL);
 
@@ -240,10 +233,7 @@ static void *erofs_vmap(struct page **pages, unsigned int count)
 
 static void erofs_vunmap(const void *mem, unsigned int count)
 {
-	if (!use_vmap)
-		vm_unmap_ram(mem, count);
-	else
-		vunmap(mem);
+	vm_unmap_ram(mem, count);
 }
 
 static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
-- 
2.17.1