btrfs: subpage: make btrfs_alloc_subpage() return btrfs_subpage directly

The existing calling convention of btrfs_alloc_subpage() is pretty
awful.  Change it to a more common pattern by returning struct
btrfs_subpage directly and let the caller to determine if the call
succeeded.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 19889dbfcf154a8e2a68d6974cf159dc8c8b3d9c..f7895b34011eb67c8f51f60cd628a2a9eb9586e7 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -6138,9 +6138,9 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
                 * support, so we still preallocate the memory in the loop.
                 */
                if (fs_info->sectorsize < PAGE_SIZE) {
-                       ret = btrfs_alloc_subpage(fs_info, &prealloc,
-                                                 BTRFS_SUBPAGE_METADATA);
-                       if (ret < 0) {
+                       prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA);
+                       if (IS_ERR(prealloc)) {
+                               ret = PTR_ERR(prealloc);
                                unlock_page(p);
                                put_page(p);
                                exists = ERR_PTR(ret);

diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c
index ff1c6ba34a4d0be2ab5308b719a14ed9cd46887c..03dcc35d7d0b3a50f8c8916ff9899ddf0a11392f 100644 (file)
--- a/fs/btrfs/subpage.c
+++ b/fs/btrfs/subpage.c
@@ -66,8 +66,7 @@
 int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
                         struct page *page, enum btrfs_subpage_type type)
 {
-       struct btrfs_subpage *subpage = NULL;
-       int ret;
+       struct btrfs_subpage *subpage;
 
        /*
         * We have cases like a dummy extent buffer page, which is not mappped
@@ -75,13 +74,15 @@ int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
         */
        if (page->mapping)
                ASSERT(PageLocked(page));
+
        /* Either not subpage, or the page already has private attached */
        if (fs_info->sectorsize == PAGE_SIZE || PagePrivate(page))
                return 0;
 
-       ret = btrfs_alloc_subpage(fs_info, &subpage, type);
-       if (ret < 0)
-               return ret;
+       subpage = btrfs_alloc_subpage(fs_info, type);
+       if (IS_ERR(subpage))
+               return  PTR_ERR(subpage);
+
        attach_page_private(page, subpage);
        return 0;
 }
@@ -100,23 +101,25 @@ void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info,
        btrfs_free_subpage(subpage);
 }
 
-int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
-                       struct btrfs_subpage **ret,
-                       enum btrfs_subpage_type type)
+struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
+                                         enum btrfs_subpage_type type)
 {
+       struct btrfs_subpage *ret;
+
        ASSERT(fs_info->sectorsize < PAGE_SIZE);
 
-       *ret = kzalloc(sizeof(struct btrfs_subpage), GFP_NOFS);
-       if (!*ret)
-               return -ENOMEM;
-       spin_lock_init(&(*ret)->lock);
+       ret = kzalloc(sizeof(struct btrfs_subpage), GFP_NOFS);
+       if (!ret)
+               return ERR_PTR(-ENOMEM);
+
+       spin_lock_init(&ret->lock);
        if (type == BTRFS_SUBPAGE_METADATA) {
-               atomic_set(&(*ret)->eb_refs, 0);
+               atomic_set(&ret->eb_refs, 0);
        } else {
-               atomic_set(&(*ret)->readers, 0);
-               atomic_set(&(*ret)->writers, 0);
+               atomic_set(&ret->readers, 0);
+               atomic_set(&ret->writers, 0);
        }
-       return 0;
+       return ret;
 }
 
 void btrfs_free_subpage(struct btrfs_subpage *subpage)

diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index 0120948f37a107d04974619f04cc433641b9bea4..fdcadc5193c1d9fa703f6f55335a8322900dad58 100644 (file)
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -59,9 +59,8 @@ void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info,
                          struct page *page);
 
 /* Allocate additional data where page represents more than one sector */
-int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
-                       struct btrfs_subpage **ret,
-                       enum btrfs_subpage_type type);
+struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
+                                         enum btrfs_subpage_type type);
 void btrfs_free_subpage(struct btrfs_subpage *subpage);
 
 void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,