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Commit 7b7b68bb authored by Jiri Kosina's avatar Jiri Kosina
Browse files

floppy: bail out in open() if drive is not responding to block0 read 



In case reading of block 0 during open() fails, it is not the right thing
to let open() succeed.

Fix this by introducing FD_OPEN_SHOULD_FAIL_BIT flag, and setting it in
case the bio callback encounters an error while trying to read block 0.

As a bonus, this works around certain broken userspace (blkid), which is
not able to properly handle read()s returning IO errors. Hence be nice to
those, and bail out during open() already; if block 0 is not readable,
read()s are not going to provide any meaningful data anyway.

Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 8586ea96

drivers/block/floppy.c

+27 −9
Original line number Diff line number Diff line
@@ -3691,9 +3691,12 @@ static int floppy_open(struct block_device *bdev, fmode_t mode) 
	if (!(mode & FMODE_NDELAY)) {

		if (mode & (FMODE_READ|FMODE_WRITE)) {

			UDRS->last_checked = 0;

			clear_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags);

			check_disk_change(bdev);

			if (test_bit(FD_DISK_CHANGED_BIT, &UDRS->flags))

				goto out;

			if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags))

				goto out;

		}

		res = -EROFS;

		if ((mode & FMODE_WRITE) &&
@@ -3746,17 +3749,29 @@ static unsigned int floppy_check_events(struct gendisk *disk, 
 * a disk in the drive, and whether that disk is writable.

 */



static void floppy_rb0_complete(struct bio *bio, int err)

struct rb0_cbdata {

	int drive;

	struct completion complete;

};



static void floppy_rb0_cb(struct bio *bio, int err)

{

	complete((struct completion *)bio->bi_private);

	struct rb0_cbdata *cbdata = (struct rb0_cbdata *)bio->bi_private;

	int drive = cbdata->drive;



	if (err) {

		pr_info("floppy: error %d while reading block 0", err);

		set_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags);

	}

	complete(&cbdata->complete);

}



static int __floppy_read_block_0(struct block_device *bdev)

static int __floppy_read_block_0(struct block_device *bdev, int drive)

{

	struct bio bio;

	struct bio_vec bio_vec;

	struct completion complete;

	struct page *page;

	struct rb0_cbdata cbdata;

	size_t size;



	page = alloc_page(GFP_NOIO);
@@ -3769,6 +3784,8 @@ static int __floppy_read_block_0(struct block_device *bdev) 
	if (!size)

		size = 1024;



	cbdata.drive = drive;



	bio_init(&bio);

	bio.bi_io_vec = &bio_vec;

	bio_vec.bv_page = page;
@@ -3779,13 +3796,14 @@ static int __floppy_read_block_0(struct block_device *bdev) 
	bio.bi_bdev = bdev;

	bio.bi_iter.bi_sector = 0;

	bio.bi_flags = (1 << BIO_QUIET);

	init_completion(&complete);

	bio.bi_private = &complete;

	bio.bi_end_io = floppy_rb0_complete;

	bio.bi_private = &cbdata;

	bio.bi_end_io = floppy_rb0_cb;



	submit_bio(READ, &bio);

	process_fd_request();

	wait_for_completion(&complete);



	init_completion(&cbdata.complete);

	wait_for_completion(&cbdata.complete);



	__free_page(page);
@@ -3827,7 +3845,7 @@ static int floppy_revalidate(struct gendisk *disk) 
			UDRS->generation++;

		if (drive_no_geom(drive)) {

			/* auto-sensing */

			res = __floppy_read_block_0(opened_bdev[drive]);

			res = __floppy_read_block_0(opened_bdev[drive], drive);

		} else {

			if (cf)

				poll_drive(false, FD_RAW_NEED_DISK);

include/uapi/linux/fd.h

+2 −1
Original line number Diff line number Diff line
@@ -185,7 +185,8 @@ enum { 
				 * to clear media change status */

	FD_UNUSED_BIT,

	FD_DISK_CHANGED_BIT,	/* disk has been changed since last i/o */

	FD_DISK_WRITABLE_BIT	/* disk is writable */

	FD_DISK_WRITABLE_BIT,	/* disk is writable */

	FD_OPEN_SHOULD_FAIL_BIT

};



#define FDSETDRVPRM _IOW(2, 0x90, struct floppy_drive_params)