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 <>
parent 8586ea96
......@@ -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);
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);
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; = drive;
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);
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);
......@@ -3827,7 +3845,7 @@ static int floppy_revalidate(struct gendisk *disk)
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);
......@@ -185,7 +185,8 @@ enum {
* to clear media change status */
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 */
#define FDSETDRVPRM _IOW(2, 0x90, struct floppy_drive_params)
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