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-rw-r--r--block/bio.c39
-rw-r--r--fs/buffer.c25
-rw-r--r--include/linux/bio.h1
3 files changed, 41 insertions, 24 deletions
diff --git a/block/bio.c b/block/bio.c
index a5d75f6bf4c7..006bcc52a77e 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -538,6 +538,45 @@ void zero_fill_bio_iter(struct bio *bio, struct bvec_iter start)
}
EXPORT_SYMBOL(zero_fill_bio_iter);
+void bio_truncate(struct bio *bio, unsigned new_size)
+{
+ struct bio_vec bv;
+ struct bvec_iter iter;
+ unsigned int done = 0;
+ bool truncated = false;
+
+ if (new_size >= bio->bi_iter.bi_size)
+ return;
+
+ if (bio_data_dir(bio) != READ)
+ goto exit;
+
+ bio_for_each_segment(bv, bio, iter) {
+ if (done + bv.bv_len > new_size) {
+ unsigned offset;
+
+ if (!truncated)
+ offset = new_size - done;
+ else
+ offset = 0;
+ zero_user(bv.bv_page, offset, bv.bv_len - offset);
+ truncated = true;
+ }
+ done += bv.bv_len;
+ }
+
+ exit:
+ /*
+ * Don't touch bvec table here and make it really immutable, since
+ * fs bio user has to retrieve all pages via bio_for_each_segment_all
+ * in its .end_bio() callback.
+ *
+ * It is enough to truncate bio by updating .bi_size since we can make
+ * correct bvec with the updated .bi_size for drivers.
+ */
+ bio->bi_iter.bi_size = new_size;
+}
+
/**
* bio_put - release a reference to a bio
* @bio: bio to release reference to
diff --git a/fs/buffer.c b/fs/buffer.c
index d8c7242426bb..e94a6619464c 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3034,8 +3034,6 @@ static void end_bio_bh_io_sync(struct bio *bio)
void guard_bio_eod(int op, struct bio *bio)
{
sector_t maxsector;
- struct bio_vec *bvec = bio_last_bvec_all(bio);
- unsigned truncated_bytes;
struct hd_struct *part;
rcu_read_lock();
@@ -3061,28 +3059,7 @@ void guard_bio_eod(int op, struct bio *bio)
if (likely((bio->bi_iter.bi_size >> 9) <= maxsector))
return;
- /* Uhhuh. We've got a bio that straddles the device size! */
- truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9);
-
- /*
- * The bio contains more than one segment which spans EOD, just return
- * and let IO layer turn it into an EIO
- */
- if (truncated_bytes > bvec->bv_len)
- return;
-
- /* Truncate the bio.. */
- bio->bi_iter.bi_size -= truncated_bytes;
- bvec->bv_len -= truncated_bytes;
-
- /* ..and clear the end of the buffer for reads */
- if (op == REQ_OP_READ) {
- struct bio_vec bv;
-
- mp_bvec_last_segment(bvec, &bv);
- zero_user(bv.bv_page, bv.bv_offset + bv.bv_len,
- truncated_bytes);
- }
+ bio_truncate(bio, maxsector << 9);
}
static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 3cdb84cdc488..853d92ceee64 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -470,6 +470,7 @@ extern struct bio *bio_copy_user_iov(struct request_queue *,
gfp_t);
extern int bio_uncopy_user(struct bio *);
void zero_fill_bio_iter(struct bio *bio, struct bvec_iter iter);
+void bio_truncate(struct bio *bio, unsigned new_size);
static inline void zero_fill_bio(struct bio *bio)
{