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[SCSI] scsi_dh: Reference count scsi_dh_attach

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Problem reported: http://marc.info/?l=dm-devel&m=124585978305866&w=2

scsi_dh does not do a refernce count for attach/detach, and this affects
the way it is supposed to work with multipath when a device is not
in the dev_list of the hardware handler.

This patch adds a reference count that counts each attach.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
This commit is contained in:
Chandra Seetharaman 2009-06-26 19:30:06 -07:00 committed by James Bottomley
parent b4567ca630
commit 6c10db72c9
2 changed files with 18 additions and 7 deletions
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23
drivers/scsi/device_handler/scsi_dh.c
View File

@ -153,12 +153,24 @@ static int scsi_dh_handler_attach(struct scsi_device *sdev,
if (sdev->scsi_dh_data) {
if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
err = -EBUSY;
} else if (scsi_dh->attach)
else
kref_get(&sdev->scsi_dh_data->kref);
} else if (scsi_dh->attach) {
err = scsi_dh->attach(sdev);
if (!err) {
kref_init(&sdev->scsi_dh_data->kref);
sdev->scsi_dh_data->sdev = sdev;
}
}
return err;
}
static void __detach_handler (struct kref *kref)
{
struct scsi_dh_data *scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
}
/*
* scsi_dh_handler_detach - Detach a device handler from a device
* @sdev - SCSI device the device handler should be detached from
@ -180,7 +192,7 @@ static void scsi_dh_handler_detach(struct scsi_device *sdev,
scsi_dh = sdev->scsi_dh_data->scsi_dh;
if (scsi_dh && scsi_dh->detach)
scsi_dh->detach(sdev);
kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
}
/*
@ -474,7 +486,6 @@ int scsi_dh_attach(struct request_queue *q, const char *name)
if (!err) {
err = scsi_dh_handler_attach(sdev, scsi_dh);
put_device(&sdev->sdev_gendev);
}
return err;
@ -505,10 +516,8 @@ void scsi_dh_detach(struct request_queue *q)
return;
if (sdev->scsi_dh_data) {
/* if sdev is not on internal list, detach */
scsi_dh = sdev->scsi_dh_data->scsi_dh;
if (!device_handler_match(scsi_dh, sdev))
scsi_dh_handler_detach(sdev, scsi_dh);
scsi_dh_handler_detach(sdev, scsi_dh);
}
put_device(&sdev->sdev_gendev);
}

2
include/scsi/scsi_device.h
View File

@ -191,6 +191,8 @@ struct scsi_device_handler {
struct scsi_dh_data {
struct scsi_device_handler *scsi_dh;
struct scsi_device *sdev;
struct kref kref;
char buf[0];
};