Btrfs: fix unexpected return value of bio_readpage_error

With blk_status_t conversion (that are now present in master),
bio_readpage_error() may return 1 as now ->submit_bio_hook() may not set
%ret if it runs without problems.

This fixes that unexpected return value by changing
btrfs_check_repairable() to return a bool instead of updating %ret, and
patch is applicable to both codebases with and without blk_status_t.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -2257,7 +2257,7 @@ 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,
+bool btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
 			   struct io_failure_record *failrec, int failed_mirror)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
@@ -2273,7 +2273,7 @@ int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
 		btrfs_debug(fs_info,
 			"Check Repairable: cannot repair, num_copies=%d, next_mirror %d, failed_mirror %d",
 			num_copies, failrec->this_mirror, failed_mirror);
-		return 0;
+		return false;
 	}
 
 	/*
@@ -2314,10 +2314,10 @@ int btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
 		btrfs_debug(fs_info,
 			"Check Repairable: (fail) num_copies=%d, next_mirror %d, failed_mirror %d",
 			num_copies, failrec->this_mirror, failed_mirror);
-		return 0;
+		return false;
 	}
 
-	return 1;
+	return true;
 }
 
 
@@ -2380,8 +2380,8 @@ 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);
-	if (!ret) {
+	if (!btrfs_check_repairable(inode, failed_bio, failrec,
+				    failed_mirror)) {
 		free_io_failure(failure_tree, tree, failrec);
 		return -EIO;
 	}

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,
+bool btrfs_check_repairable(struct inode *inode, struct bio *failed_bio,
 			    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,