[RFC PATCH V3 1/1] block: reject I/O for same fd if block size changed
From: Minwoo Im <hidden>
Date: 2021-01-04 13:08:12
Also in:
linux-fsdevel, lkml
Subsystem:
block layer, filesystems (vfs and infrastructure), the rest · Maintainers:
Jens Axboe, Alexander Viro, Christian Brauner, Linus Torvalds
This patch fixes I/O errors during BLKRRPART ioctl() behavior right after format operation that changed logical block size of the block device with a same file descriptor opened. This issue can be easily reproduced with a single format command in case of NVMe (logical block size 512B to 4096B). nvme format /dev/nvme0n1 --lbaf=1 --force This is because the application, nvme-cli format subcommand issues an admin command followed by BLKRRPART ioctl to re-read partition information without closing the file descriptor. If file descriptor stays opened, __blkdev_get() will not be invoked at all even logical block size has been changed. It will cause I/O errors with invalid Read operations during the BLKRRPART ioctl due to i_blkbits mismatch. The invalid operations in BLKRRPART happens with under-flowed Number of LBA(NLB) values 0xffff(65535) because i_blkbits is still set to 9 even the logical block size has been updated to 4096. The BLKRRPART will lead buffer_head to hold 512B data which is less than the logical lock size of the block device. The root cause, which is because i_blkbits of inode of the block device is not updated, can be solved easily by re-opening file descriptor again from application. But, that's just for application's business and kernel should reject invalid Read operations during the BLKRRPART ioctl. This patch rejects I/O from the path of add_partitions() to avoid issuing invalid Read operations to device. It also sets a flag to gendisk in blk_queue_logical_block_size to minimize caller-side updates. Signed-off-by: Minwoo Im <redacted> --- block/blk-settings.c | 8 ++++++++ block/partitions/core.c | 11 +++++++++++ fs/block_dev.c | 6 ++++++ include/linux/genhd.h | 1 + 4 files changed, 26 insertions(+)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 43990b1d148b..84136ea4e2a4 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c@@ -328,6 +328,14 @@ EXPORT_SYMBOL(blk_queue_max_segment_size); void blk_queue_logical_block_size(struct request_queue *q, unsigned int size) { struct queue_limits *limits = &q->limits; + struct block_device *bdev; + + if (q->backing_dev_info && q->backing_dev_info->owner && + limits->logical_block_size != size) { + bdev = blkdev_get_no_open(q->backing_dev_info->owner->devt); + bdev->bd_disk->flags |= GENHD_FL_BLOCK_SIZE_CHANGED; + blkdev_put_no_open(bdev); + } limits->logical_block_size = size;
diff --git a/block/partitions/core.c b/block/partitions/core.c
index e7d776db803b..5a0330c1b6f9 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c@@ -618,6 +618,17 @@ int blk_add_partitions(struct gendisk *disk, struct block_device *bdev) if (!disk_part_scan_enabled(disk)) return 0; + /* + * Reject to check partition information if block size has been changed + * in the runtime. If block size of a block device has been changed, + * the file descriptor should be opened agian to update the blkbits. + */ + if (disk->flags & GENHD_FL_BLOCK_SIZE_CHANGED) { + pr_warn("%s: rejecting checking partition. fd should be opened again.\n", + disk->disk_name); + return -EBADFD; + } + state = check_partition(disk, bdev); if (!state) return 0;
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9293045e128c..c996de3d6084 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c@@ -131,6 +131,12 @@ EXPORT_SYMBOL(truncate_bdev_range); static void set_init_blocksize(struct block_device *bdev) { bdev->bd_inode->i_blkbits = blksize_bits(bdev_logical_block_size(bdev)); + + /* + * Allow I/O commands for this block device. We can say that this + * block device has been set to a proper block size. + */ + bdev->bd_disk->flags &= ~GENHD_FL_BLOCK_SIZE_CHANGED; } int set_blocksize(struct block_device *bdev, int size)
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 809aaa32d53c..0e0e24917003 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h@@ -103,6 +103,7 @@ struct partition_meta_info { #define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE 0x0100 #define GENHD_FL_NO_PART_SCAN 0x0200 #define GENHD_FL_HIDDEN 0x0400 +#define GENHD_FL_BLOCK_SIZE_CHANGED 0x0800 enum { DISK_EVENT_MEDIA_CHANGE = 1 << 0, /* media changed */
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2.17.1