[PATCH 5.4 024/203] fs: move guard_bio_eod() after bio_set_op_attrs

Greg Kroah-Hartman
2020-01-16T23:20:11Z

From: Ming Lei <ming.lei@redhat.com>

commit 83c9c547168e8b914ea6398430473a4de68c52cc upstream.

Commit 85a8ce62c2ea ("block: add bio_truncate to fix guard_bio_eod")
adds bio_truncate() for handling bio EOD. However, bio_truncate()
doesn't use the passed 'op' parameter from guard_bio_eod's callers.

So bio_trunacate() may retrieve wrong 'op', and zering pages may
not be done for READ bio.

Fixes this issue by moving guard_bio_eod() after bio_set_op_attrs()
in submit_bh_wbc() so that bio_truncate() can always retrieve correct
op info.

Meantime remove the 'op' parameter from guard_bio_eod() because it isn't
used any more.

Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Fixes: 85a8ce62c2ea ("block: add bio_truncate to fix guard_bio_eod")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fold in kerneldoc and bio_op() change.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

---
block/bio.c | 12 +++++++++++-
fs/buffer.c | 8 ++++----
fs/internal.h | 2 +-
fs/mpage.c | 2 +-
4 files changed, 17 insertions(+), 7 deletions(-)

--- a/block/bio.c
+++ b/block/bio.c
@@ -535,6 +535,16 @@ void zero_fill_bio_iter(struct bio *bio,
}
EXPORT_SYMBOL(zero_fill_bio_iter);

+/**
+ * bio_truncate - truncate the bio to small size of @new_size
+ * @bio: the bio to be truncated
+ * @new_size: new size for truncating the bio
+ *
+ * Description:
+ * Truncate the bio to new size of @new_size. If bio_op(bio) is
+ * REQ_OP_READ, zero the truncated part. This function should only
+ * be used for handling corner cases, such as bio eod.
+ */
void bio_truncate(struct bio *bio, unsigned new_size)
{
struct bio_vec bv;
@@ -545,7 +555,7 @@ void bio_truncate(struct bio *bio, unsig
if (new_size >= bio->bi_iter.bi_size)
return;

- if (bio_data_dir(bio) != READ)
+ if (bio_op(bio) != REQ_OP_READ)
goto exit;

bio_for_each_segment(bv, bio, iter) {
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2991,7 +2991,7 @@ static void end_bio_bh_io_sync(struct bi
* errors, this only handles the "we need to be able to
* do IO at the final sector" case.
*/
-void guard_bio_eod(int op, struct bio *bio)
+void guard_bio_eod(struct bio *bio)
{
sector_t maxsector;
struct hd_struct *part;
@@ -3055,15 +3055,15 @@ static int submit_bh_wbc(int op, int op_
bio->bi_end_io = end_bio_bh_io_sync;
bio->bi_private = bh;

- /* Take care of bh's that straddle the end of the device */
- guard_bio_eod(op, bio);
-
if (buffer_meta(bh))
op_flags |= REQ_META;
if (buffer_prio(bh))
op_flags |= REQ_PRIO;
bio_set_op_attrs(bio, op, op_flags);

+ /* Take care of bh's that straddle the end of the device */
+ guard_bio_eod(bio);
+
if (wbc) {
wbc_init_bio(wbc, bio);
wbc_account_cgroup_owner(wbc, bh->b_page, bh->b_size);
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -38,7 +38,7 @@ static inline int __sync_blockdev(struct
/*
* buffer.c
*/
-extern void guard_bio_eod(int rw, struct bio *bio);
+extern void guard_bio_eod(struct bio *bio);
extern int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
get_block_t *get_block, struct iomap *iomap);

--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -62,7 +62,7 @@ static struct bio *mpage_bio_submit(int
{
bio->bi_end_io = mpage_end_io;
bio_set_op_attrs(bio, op, op_flags);
- guard_bio_eod(op, bio);
+ guard_bio_eod(bio);
submit_bio(bio);
return NULL;
}