[PATCH v2 2/2] cdrom: gdrom: update gendisk capacity on open

[Florian Fuchs]

Update the gendisk capacity of the media. Without the capacity, the block
reads fail before reaching the request queue, which prevented ISO9660
mounts. Refresh the capacity from the TOC leadout in gdrom_bdops_open()
so it checks the inserted media.

Signed-off-by: Florian Fuchs <fuchsfl@xxxxxxxxx>
---
v1->v2: no change for gdrom_update_capacity(), but for
        gdrom_bdops_open(): handle the failure case when
        gdrom_update_capacity() fails but previous cdrom_open() succeeded,
        to cleanup the successful cdrom_open() with cdrom_release()

v1: https://lore.kernel.org/linux-sh/20260405082330.4104672-3-fuchsfl@xxxxxxxxx/
---
 drivers/cdrom/gdrom.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/cdrom/gdrom.c b/drivers/cdrom/gdrom.c
index 89938d9b2825..fb95288fad72 100644
--- a/drivers/cdrom/gdrom.c
+++ b/drivers/cdrom/gdrom.c
@@ -474,6 +474,25 @@ static const struct cdrom_device_ops gdrom_ops = {
 				  CDC_RESET | CDC_DRIVE_STATUS | CDC_CD_R,
 };
 
+static int gdrom_update_capacity(void)
+{
+	sector_t cap;
+	int ret;
+
+	if (gdrom_drivestatus(gd.cd_info, CDSL_CURRENT) != CDS_DISC_OK) {
+		set_capacity(gd.disk, 0);
+		return -ENOMEDIUM;
+	}
+	ret = gdrom_readtoc_cmd(gd.toc, 0);
+	if (ret) {
+		set_capacity(gd.disk, 0);
+		return ret;
+	}
+	cap = (sector_t)get_entry_lba(gd.toc->leadout) * GD_TO_BLK;
+	set_capacity(gd.disk, cap);
+	return 0;
+}
+
 static int gdrom_bdops_open(struct gendisk *disk, blk_mode_t mode)
 {
 	int ret;
@@ -482,6 +501,12 @@ static int gdrom_bdops_open(struct gendisk *disk, blk_mode_t mode)
 
 	mutex_lock(&gdrom_mutex);
 	ret = cdrom_open(gd.cd_info, mode);
+	if (ret)
+		goto out;
+	ret = gdrom_update_capacity();
+	if (ret)
+		cdrom_release(gd.cd_info);
+out:
 	mutex_unlock(&gdrom_mutex);
 	return ret;
 }
-- 
2.43.0