On Apr 02, 2024 / 18:01, Christoph Hellwig wrote:
> Commit 4601b4b130de ("block: reopen the device in blkdev_reread_part")
> lost the propagation of I/O errors from the low-level read of the
> partition table to the user space caller of the BLKRRPART.
>
> Apparently some user space relies on, so restore the propagation. This
> isn't exactly pretty as other block device open calls explicitly do not
> are about these errors, so add a new BLK_OPEN_STRICT_SCAN to opt into
> the error propagation.
>
> Fixes: 4601b4b130de ("block: reopen the device in blkdev_reread_part")
> Reported-by: Saranya Muruganandam <saranyamohan@xxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
I should have commented on this patch with the correct authorship instead of the
patch that Saranya posted. With this patch I observe unexpected EINVAL. Please
find a couple of comments in line.
> ---
> block/bdev.c | 29 +++++++++++++++++++----------
> block/ioctl.c | 3 ++-
> include/linux/blkdev.h | 2 ++
> 3 files changed, 23 insertions(+), 11 deletions(-)
>
> diff --git a/block/bdev.c b/block/bdev.c
> index 7a5f611c3d2e3e..42940bced33bb4 100644
> --- a/block/bdev.c
> +++ b/block/bdev.c
> @@ -652,6 +652,14 @@ static void blkdev_flush_mapping(struct block_device *bdev)
> bdev_write_inode(bdev);
> }
>
> +static void blkdev_put_whole(struct block_device *bdev)
> +{
> + if (atomic_dec_and_test(&bdev->bd_openers))
> + blkdev_flush_mapping(bdev);
> + if (bdev->bd_disk->fops->release)
> + bdev->bd_disk->fops->release(bdev->bd_disk);
> +}
> +
> static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode)
> {
> struct gendisk *disk = bdev->bd_disk;
> @@ -670,20 +678,21 @@ static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode)
>
> if (!atomic_read(&bdev->bd_openers))
> set_init_blocksize(bdev);
> - if (test_bit(GD_NEED_PART_SCAN, &disk->state))
> - bdev_disk_changed(disk, false);
> atomic_inc(&bdev->bd_openers);
> + if (test_bit(GD_NEED_PART_SCAN, &disk->state)) {
> + /*
> + * Only return scanning errors if we are called from conexts
Nit: s/conexts/contexts/
> + * that explicitly want them, e.g. the BLKRRPART ioctl.
> + */
> + ret = bdev_disk_changed(disk, false);
> + if (ret && (mode & BLK_OPEN_STRICT_SCAN)) {
> + blkdev_put_whole(bdev);
> + return ret;
> + }
> + }
> return 0;
> }
>
> -static void blkdev_put_whole(struct block_device *bdev)
> -{
> - if (atomic_dec_and_test(&bdev->bd_openers))
> - blkdev_flush_mapping(bdev);
> - if (bdev->bd_disk->fops->release)
> - bdev->bd_disk->fops->release(bdev->bd_disk);
> -}
> -
> static int blkdev_get_part(struct block_device *part, blk_mode_t mode)
> {
> struct gendisk *disk = part->bd_disk;
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 0c76137adcaaa5..128f503828cee7 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -562,7 +562,8 @@ static int blkdev_common_ioctl(struct block_device *bdev, blk_mode_t mode,
> return -EACCES;
> if (bdev_is_partition(bdev))
> return -EINVAL;
> - return disk_scan_partitions(bdev->bd_disk, mode);
> + return disk_scan_partitions(bdev->bd_disk,
> + mode | BLK_OPEN_STRICT_SCAN);
> case BLKTRACESTART:
> case BLKTRACESTOP:
> case BLKTRACETEARDOWN:
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 79ed07bd652ac4..0b39df4864ef19 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -129,6 +129,8 @@ typedef unsigned int __bitwise blk_mode_t;
> #define BLK_OPEN_WRITE_IOCTL ((__force blk_mode_t)(1 << 4))
> /* open is exclusive wrt all other BLK_OPEN_WRITE opens to the device */
> #define BLK_OPEN_RESTRICT_WRITES ((__force blk_mode_t)(1 << 5))
> +/* return partition scanning errors */
> +#define BLK_OPEN_STRICT_SCAN ((__force blk_mode_t)(1 << 5))
The line above assigns the same number for BLK_OPEN_STRICT_SCAN and
BLK_OPEN_RESTRICT_WRITES, then blockdev --rereadpt fails with EINVAL,
not EIO. I modified it to "1 << 6", then it looks working good.
>
> struct gendisk {
> /*
> --
> 2.39.2
>
