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: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 6b29c44..2023043 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3691,9 +3691,12 @@
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 @@
* 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 @@
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 @@
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 @@
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);