[PATCH v2 3/3] btrfs: expand subpage support to any PAGE_SIZE > 4K

[Qu Wenruo <wqu@suse.com>]

With the recent change in metadata handling, we can handle metadata in
the following cases:

- nodesize < PAGE_SIZE and sectorsize < PAGE_SIZE
  Go subpage routine for both metadata and data.

- nodesize < PAGE_SIZE and sectorsize >= PAGE_SIZE
  Invalid case for now. As we require nodesize >= sectorsize.

- nodesize >= PAGE_SIZE and sectorsize < PAGE_SIZE
  Go subpage routine for data, but regular page routine for metadata.

- nodesize >= PAGE_SIZE and sectorsize >= PAGE_SIZE
  Go regular page routine for both metadata and data.

Previously we require 64K page size for subpage as we need to ensure any
tree block can be fit into one page, as at that time, we don't have
support subpage metadata crossing multiple pages.

But now since we allow nodesize >= PAGE_SIZE case to regular page
routine, there is no such limitation any more.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/disk-io.c | 16 +++++++++++-----
 fs/btrfs/sysfs.c   | 11 +++++------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 884e0b543136..ffb8c811aeea 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2752,12 +2752,18 @@ static int validate_super(struct btrfs_fs_info *fs_info,
 	}
 
 	/*
-	 * For 4K page size, we only support 4K sector size.
-	 * For 64K page size, we support 64K and 4K sector sizes.
+	 * We only support sectorsize <= PAGE_SIZE case.
+	 *
+	 * For 4K page size (e.g. x86_64), it only supports 4K sector size.
+	 * For 16K page size (e.g. PPC/ARM), it supports 4K, 8K and 16K
+	 * sector sizes.
+	 * For 64K and higher page size (e.g. PPC/ARM), it supports 4K, 8K,
+	 * 16K, 32K and 64K sector sizes (aka, all sector sizes).
+	 *
+	 * For the future, 4K will be the default sectorsize for all btrfs
+	 * and will get supported on all archtectures.
 	 */
-	if ((PAGE_SIZE == SZ_4K && sectorsize != PAGE_SIZE) ||
-	    (PAGE_SIZE == SZ_64K && (sectorsize != SZ_4K &&
-				     sectorsize != SZ_64K))) {
+	if (sectorsize > PAGE_SIZE) {
 		btrfs_err(fs_info,
 			"sectorsize %llu not yet supported for page size %lu",
 			sectorsize, PAGE_SIZE);
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index beb7f72d50b8..6a01be4ef3b4 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -390,13 +390,12 @@ static ssize_t supported_sectorsizes_show(struct kobject *kobj,
 					  char *buf)
 {
 	ssize_t ret = 0;
+	u32 sectorsize;
 
-	/* 4K sector size is also supported with 64K page size */
-	if (PAGE_SIZE == SZ_64K)
-		ret += sysfs_emit_at(buf, ret, "%u ", SZ_4K);
-
-	/* Only sectorsize == PAGE_SIZE is now supported */
-	ret += sysfs_emit_at(buf, ret, "%lu\n", PAGE_SIZE);
+	/* We support any sectorsize <= PAGE_SIZE */
+	for (sectorsize = SZ_4K; sectorsize <= PAGE_SIZE; sectorsize <<= 1)
+		ret += sysfs_emit_at(buf, ret, "%u%s", sectorsize,
+				     sectorsize == PAGE_SIZE ? "\n" : " ");
 
 	return ret;
 }
-- 
2.34.1