For subpage case, we need to allocate new memory for each metadata page.
So we need to:
- Allow attach_extent_buffer_page() to return int
To indicate allocation failure
- Prealloc page->private for alloc_extent_buffer()
We don't want to call memory allocation with spinlock hold, so
do preallocation before we acquire the spin lock.
- Handle subpage and regular case differently in
attach_extent_buffer_page()
For regular case, just do the usual thing.
For subpage case, allocate new memory and update the tree_block
bitmap.
The bitmap update will be handled by new subpage specific helper,
btrfs_subpage_set_tree_block().
Signed-off-by: Qu Wenruo <[email protected]>
---
fs/btrfs/extent_io.c | 69 +++++++++++++++++++++++++++++++++++---------
fs/btrfs/subpage.h | 44 ++++++++++++++++++++++++++++
2 files changed, 99 insertions(+), 14 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 6350c2687c7e..51dd7ec3c2b3 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -24,6 +24,7 @@
#include "rcu-string.h"
#include "backref.h"
#include "disk-io.h"
+#include "subpage.h"
static struct kmem_cache *extent_state_cache;
static struct kmem_cache *extent_buffer_cache;
@@ -3142,22 +3143,41 @@ static int submit_extent_page(unsigned int opf,
return ret;
}
-static void attach_extent_buffer_page(struct extent_buffer *eb,
+static int attach_extent_buffer_page(struct extent_buffer *eb,
struct page *page)
{
- /*
- * If the page is mapped to btree inode, we should hold the private
- * lock to prevent race.
- * For cloned or dummy extent buffers, their pages are not mapped and
- * will not race with any other ebs.
- */
- if (page->mapping)
- lockdep_assert_held(&page->mapping->private_lock);
+ struct btrfs_fs_info *fs_info = eb->fs_info;
+ int ret;
- if (!PagePrivate(page))
- attach_page_private(page, eb);
- else
- WARN_ON(page->private != (unsigned long)eb);
+ if (fs_info->sectorsize == PAGE_SIZE) {
+ /*
+ * If the page is mapped to btree inode, we should hold the
+ * private lock to prevent race.
+ * For cloned or dummy extent buffers, their pages are not
+ * mapped and will not race with any other ebs.
+ */
+ if (page->mapping)
+ lockdep_assert_held(&page->mapping->private_lock);
+
+ if (!PagePrivate(page))
+ attach_page_private(page, eb);
+ else
+ WARN_ON(page->private != (unsigned long)eb);
+ return 0;
+ }
+
+ /* Already mapped, just update the existing range */
+ if (PagePrivate(page))
+ goto update_bitmap;
+
+ /* Do new allocation to attach subpage */
+ ret = btrfs_attach_subpage(fs_info, page);
+ if (ret < 0)
+ return ret;
+
+update_bitmap:
+ btrfs_subpage_set_tree_block(fs_info, page, eb->start, eb->len);
+ return 0;
}
void set_page_extent_mapped(struct page *page)
@@ -5067,12 +5087,19 @@ struct extent_buffer *btrfs_clone_extent_buffer(const
struct extent_buffer *src)
return NULL;
for (i = 0; i < num_pages; i++) {
+ int ret;
+
p = alloc_page(GFP_NOFS);
if (!p) {
btrfs_release_extent_buffer(new);
return NULL;
}
- attach_extent_buffer_page(new, p);
+ ret = attach_extent_buffer_page(new, p);
+ if (ret < 0) {
+ put_page(p);
+ btrfs_release_extent_buffer(new);
+ return NULL;
+ }
WARN_ON(PageDirty(p));
SetPageUptodate(p);
new->pages[i] = p;
@@ -5321,6 +5348,18 @@ struct extent_buffer *alloc_extent_buffer(struct
btrfs_fs_info *fs_info,
goto free_eb;
}
+ /*
+ * Preallocate page->private for subpage case, so that
+ * we won't allocate memory with private_lock hold.
+ */
+ ret = btrfs_attach_subpage(fs_info, p);
+ if (ret < 0) {
+ unlock_page(p);
+ put_page(p);
+ exists = ERR_PTR(-ENOMEM);
+ goto free_eb;
+ }
+
