[PATCH v2 13/51] btrfs: avoid access to .bi_vcnt directly

Ming Lei
2017-06-26T12:09:56Z

BTRFS uses bio->bi_vcnt to figure out page numbers, this
way becomes not correct once we start to enable multipage
bvec.

So use bio_for_each_segment_all() to do that instead.

Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: linux-btrfs@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
fs/btrfs/extent_io.c | 21 +++++++++++++++++----
fs/btrfs/extent_io.h | 2 +-
2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 0863164d97d2..5b453cada1ea 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2258,7 +2258,7 @@ int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
return 0;
}

-int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
+int btrfs_check_repairable(struct inode *inode, unsigned failed_bio_pages,
struct io_failure_record *failrec, int failed_mirror)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
@@ -2282,7 +2282,7 @@ int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
* a) deliver good data to the caller
* b) correct the bad sectors on disk
*/
- if (failed_bio->bi_vcnt > 1) {
+ if (failed_bio_pages > 1) {
/*
* to fulfill b), we need to know the exact failing sectors, as
* we don't want to rewrite any more than the failed ones. thus,
@@ -2355,6 +2355,17 @@ struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
return bio;
}

+static unsigned int get_bio_pages(struct bio *bio)
+{
+ unsigned i;
+ struct bio_vec *bv;
+
+ bio_for_each_segment_all(bv, bio, i)
+ ;
+
+ return i;
+}
+
/*
* this is a generic handler for readpage errors (default
* readpage_io_failed_hook). if other copies exist, read those and write back
@@ -2375,6 +2386,7 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
int read_mode = 0;
blk_status_t status;
int ret;
+ unsigned failed_bio_pages = get_bio_pages(failed_bio);

BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);

@@ -2382,13 +2394,14 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
if (ret)
return ret;

- ret = btrfs_check_repairable(inode, failed_bio, failrec, failed_mirror);
+ ret = btrfs_check_repairable(inode, failed_bio_pages, failrec,
+ failed_mirror);
if (!ret) {
free_io_failure(failure_tree, tree, failrec);
return -EIO;
}

- if (failed_bio->bi_vcnt > 1)
+ if (failed_bio_pages > 1)
read_mode |= REQ_FAILFAST_DEV;

phy_offset >>= inode->i_sb->s_blocksize_bits;
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index d4942d94a16b..90681d1f0786 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -539,7 +539,7 @@ void btrfs_free_io_failure_record(struct btrfs_inode *inode, u64 start,
u64 end);
int btrfs_get_io_failure_record(struct inode *inode, u64 start, u64 end,
struct io_failure_record **failrec_ret);
-int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
+int btrfs_check_repairable(struct inode *inode, unsigned failed_bio_pages,
struct io_failure_record *failrec, int fail_mirror);
struct bio *btrfs_create_repair_bio(struct inode *inode, struct bio *failed_bio,
struct io_failure_record *failrec,
--
2.9.4