[PATCH 13/17] btrfs: extent_io: only require sector size alignment for page read

Qu Wenruo
2020-09-08T07:53:18Z

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, while 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 | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 81e43d99feda..a83b63ecc5f8 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2819,6 +2819,7 @@ 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;

@@ -2829,13 +2830,17 @@ 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)
+ * 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) ||
+ !IS_ALIGNED(bvec->bv_offset + bvec->bv_len, sectorsize)) {
+ if (!IS_ALIGNED(bvec->bv_offset + bvec->bv_len,
+ sectorsize))
btrfs_err(fs_info,
"partial page read in btrfs with offset %u and length %u",
bvec->bv_offset, bvec->bv_len);
@@ -2845,8 +2850,8 @@ static void end_bio_extent_readpage(struct bio *bio)
bvec->bv_offset, bvec->bv_len);
}

- start = page_offset(page);
- end = start + bvec->bv_offset + bvec->bv_len - 1;
+ 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