For subpage case, grab_extent_buffer() can't really get an extent buffer
just from btrfs_subpage.
We have radix tree lock protecting us from inserting the same eb into
the tree. Thus we don't really need to do the extra hassle, just let
alloc_extent_buffer() handle the existing eb in radix tree.
Now if two ebs are being allocated as the same time, one will fail with
-EEIXST when inserting into the radix tree.
So for grab_extent_buffer(), just always return NULL for subpage case.
Signed-off-by: Qu Wenruo <w...@suse.com>
Reviewed-by: David Sterba <dste...@suse.com>
Signed-off-by: David Sterba <dste...@suse.com>
---
fs/btrfs/extent_io.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ea105cb69e3a..16a29f63cfd1 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5282,10 +5282,19 @@ struct extent_buffer *alloc_test_extent_buffer(struct
btrfs_fs_info *fs_info,
}
#endif
-static struct extent_buffer *grab_extent_buffer(struct page *page)
+static struct extent_buffer *grab_extent_buffer(
+ struct btrfs_fs_info *fs_info, struct page *page)
{
struct extent_buffer *exists;
+ /*
+ * For subpage case, we completely rely on radix tree to ensure we
+ * don't try to insert two ebs for the same bytenr. So here we always
+ * return NULL and just continue.
+ */
+ if (fs_info->sectorsize < PAGE_SIZE)
+ return NULL;
+
/* Page not yet attached to an extent buffer */
if (!PagePrivate(page))
return NULL;
@@ -5371,7 +5380,7 @@ struct extent_buffer *alloc_extent_buffer(struct
btrfs_fs_info *fs_info,
}
spin_lock(&mapping->private_lock);
- exists = grab_extent_buffer(p);
+ exists = grab_extent_buffer(fs_info, p);
if (exists) {
spin_unlock(&mapping->private_lock);
unlock_page(p);
--
2.30.0
