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| author | Tejun Heo <tj@kernel.org> | 2011-04-29 10:15:14 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-05-21 15:13:33 -0700 |
| commit | 9f5cc5c89537184cf45a7e069330c85428a7fc09 (patch) | |
| tree | ee9ab2f23450bd2e8308a89a7d3c915ac5bf7208 | |
| parent | b106c56573f9656e3cf863781dd5c0895d0f120d (diff) | |
| download | lwn-9f5cc5c89537184cf45a7e069330c85428a7fc09.tar.gz lwn-9f5cc5c89537184cf45a7e069330c85428a7fc09.zip | |
cdrom: always check_disk_change() on open
commit bf2253a6f00e8fea5b026e471e9f0d0a1b3621f2 upstream.
cdrom_open() called check_disk_change() after the rest of open path
succeeded which leads to the following bizarre behavior.
* After media change, if the device opened without O_NONBLOCK,
open_for_data() naturally fails with -ENOMEDIA and
check_disk_change() is never called. The media is known to be gone
and the open failure makes it obvious to the userland but device
invalidation never happens.
* But if the device is opened with O_NONBLOCK, all the checks are
bypassed and cdrom_open() doesn't notice that the media is not there
and check_disk_change() is called and invalidation happens.
There's nothing to be gained by avoiding calling check_disk_change()
on open failure. Common cases end up calling check_disk_change()
anyway. All we get is inconsistent behavior.
Fix it by moving check_disk_change() invocation to the top of
cdrom_open() so that it always gets called regardless of how the rest
of open proceeds.
Stable: 2.6.38
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Amit Shah <amit.shah@redhat.com>
Tested-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/cdrom/cdrom.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index e2c48a7eccff..5ade78a01c4d 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -986,6 +986,9 @@ int cdrom_open(struct cdrom_device_info *cdi, struct block_device *bdev, fmode_t cdinfo(CD_OPEN, "entering cdrom_open\n"); + /* open is event synchronization point, check events first */ + check_disk_change(bdev); + /* if this was a O_NONBLOCK open and we should honor the flags, * do a quick open without drive/disc integrity checks. */ cdi->use_count++; @@ -1012,9 +1015,6 @@ int cdrom_open(struct cdrom_device_info *cdi, struct block_device *bdev, fmode_t cdinfo(CD_OPEN, "Use count for \"/dev/%s\" now %d\n", cdi->name, cdi->use_count); - /* Do this on open. Don't wait for mount, because they might - not be mounting, but opening with O_NONBLOCK */ - check_disk_change(bdev); return 0; err_release: if (CDROM_CAN(CDC_LOCK) && cdi->options & CDO_LOCK) { |