[PATCH v4 12/68] btrfs: extent_io: only require sector size alignment for page read

[Qu Wenruo <wqu@suse.com>]

If we're reading partial page, btrfs will warn about this as our
read/write are always done in sector size, which equals page size.

But for the incoming subpage RO support, our data read is only aligned
to sectorsize, which can be smaller than page size.

Thus here we change the warning condition to check it against
sectorsize, thus the behavior is not changed for regular sectorsize ==
PAGE_SIZE case, and won't report error for subpage read.

Also, pass the proper start/end with bv_offset for check_data_csum() to
handle.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/extent_io.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index f20b8e886724..ce5b23169e47 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2834,6 +2834,7 @@ static void end_bio_extent_readpage(struct bio *bio)
 		struct page *page = bvec->bv_page;
 		struct inode *inode = page->mapping->host;
 		struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+		u32 sectorsize = fs_info->sectorsize;
 		bool data_inode = btrfs_ino(BTRFS_I(inode))
 			!= BTRFS_BTREE_INODE_OBJECTID;
 
@@ -2844,24 +2845,25 @@ static void end_bio_extent_readpage(struct bio *bio)
 		tree = &BTRFS_I(inode)->io_tree;
 		failure_tree = &BTRFS_I(inode)->io_failure_tree;
 
-		/* We always issue full-page reads, but if some block
+		/*
+		 * We always issue full-sector reads, but if some block
 		 * in a page fails to read, blk_update_request() will
 		 * advance bv_offset and adjust bv_len to compensate.
-		 * Print a warning for nonzero offsets, and an error
-		 * if they don't add up to a full page.  */
-		if (bvec->bv_offset || bvec->bv_len != PAGE_SIZE) {
-			if (bvec->bv_offset + bvec->bv_len != PAGE_SIZE)
-				btrfs_err(fs_info,
-					"partial page read in btrfs with offset %u and length %u",
-					bvec->bv_offset, bvec->bv_len);
-			else
-				btrfs_info(fs_info,
-					"incomplete page read in btrfs with offset %u and length %u",
-					bvec->bv_offset, bvec->bv_len);
-		}
-
-		start = page_offset(page);
-		end = start + bvec->bv_offset + bvec->bv_len - 1;
+		 * Print a warning for unaligned offsets, and an error
+		 * if they don't add up to a full sector.
+		 */
+		if (!IS_ALIGNED(bvec->bv_offset, sectorsize))
+			btrfs_err(fs_info,
+		"partial page read in btrfs with offset %u and length %u",
+				  bvec->bv_offset, bvec->bv_len);
+		else if (!IS_ALIGNED(bvec->bv_offset + bvec->bv_len,
+				     sectorsize))
+			btrfs_info(fs_info,
+		"incomplete page read in btrfs with offset %u and length %u",
+				   bvec->bv_offset, bvec->bv_len);
+
+		start = page_offset(page) + bvec->bv_offset;
+		end = start + bvec->bv_len - 1;
 		len = bvec->bv_len;
 
 		mirror = io_bio->mirror_num;
-- 
2.28.0