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scst_vdisk: Make the filename modifiable

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When VAAI support is not needed can be convenient to use the
vdisk_blockio handler to handle I/O redirection between nodes in a
H.A. setup. Making the filename modifiable allows to keep the LUN
associations of an SCST device that is used for I/O redirection in
such a setup. This is a slightly modified version of a patch
provided by Marc Smith <marc.smith@parodyne.com>.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@7497 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2018-10-06 21:59:54 +00:00
parent 5b56580253
commit a1c2a08d95
1 changed files with 105 additions and 1 deletions
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scst/src/dev_handlers/scst_vdisk.c
+105 -1
View File
@@ -443,6 +443,8 @@ static ssize_t vdisk_sysfs_removable_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf);
static ssize_t vdev_sysfs_filename_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf);
static ssize_t vdev_sysfs_filename_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t count);
static ssize_t vdev_sysfs_cluster_mode_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf);
static ssize_t vdev_sysfs_cluster_mode_store(struct kobject *kobj,
@@ -546,7 +548,8 @@ static struct kobj_attribute vdev_read_zero_attr =
static struct kobj_attribute vdisk_removable_attr =
__ATTR(removable, S_IRUGO, vdisk_sysfs_removable_show, NULL);
static struct kobj_attribute vdisk_filename_attr =
__ATTR(filename, S_IRUGO, vdev_sysfs_filename_show, NULL);
__ATTR(filename, S_IWUSR|S_IRUGO, vdev_sysfs_filename_show,
vdev_sysfs_filename_store);
static struct kobj_attribute vdisk_cluster_mode_attr =
__ATTR(cluster_mode, S_IWUSR|S_IRUGO, vdev_sysfs_cluster_mode_show,
vdev_sysfs_cluster_mode_store);
@@ -9491,6 +9494,107 @@ out:
return res;
}
static int vdev_sysfs_process_filename_store(struct scst_sysfs_work_item *work)
{
struct scst_device *dev = work->dev;
struct scst_vdisk_dev *virt_dev;
int length = strlen(work->buf);
char *p, *fn;
const char *filename = NULL;
int res;
res = mutex_lock_interruptible(&scst_mutex);
if (res)
goto out;
res = -EINVAL;
/* Serialize against vdisk_open_fd() and vdisk_close_fd() calls. */
scst_alua_lock();
/*
* This is safe since we hold a reference on dev_kobj and since
* scst_assign_dev_handler() waits until all dev_kobj references
* have been dropped before invoking .detach().
*/
virt_dev = dev->dh_priv;
if (virt_dev->dev_active) {
PRINT_ERROR("vdev %s: can't change the filename because the device is still active",
dev->virt_name);
goto unlock;
}
p = work->buf;
while (isspace(*p) && *p)
p++;
if (*p == '\0') {
PRINT_ERROR("Filename is missing");
goto unlock;
}
filename = p;
p = &work->buf[length - 1];
while (isspace(*p))
p--;
*(p + 1) = '\0';
if (*filename != '/') {
PRINT_ERROR("Path \"%s\" is not absolute", filename);
goto unlock;
}
fn = kstrdup(filename, GFP_KERNEL);
if (fn == NULL) {
PRINT_ERROR("Filename allocation failed");
goto unlock;
}
swap(virt_dev->filename, fn);
kfree(fn);
PRINT_INFO("vdev %s: changed filename into \"%s\"", virt_dev->name,
virt_dev->filename);
res = 0;
unlock:
scst_alua_unlock();
mutex_unlock(&scst_mutex);
out:
kobject_put(&dev->dev_kobj);
return res;
}
static ssize_t vdev_sysfs_filename_store(struct kobject *kobj,
struct kobj_attribute *attr, const char *buf, size_t count)
{
struct scst_device *dev = container_of(kobj, struct scst_device,
dev_kobj);
struct scst_sysfs_work_item *work;
char *arg;
int res;
TRACE_ENTRY();
res = -ENOMEM;
arg = kasprintf(GFP_KERNEL, "%.*s", (int)count, buf);
if (!arg)
goto out;
res = scst_alloc_sysfs_work(vdev_sysfs_process_filename_store,
false, &work);
if (res)
goto out;
work->dev = dev;
swap(work->buf, arg);
kobject_get(&dev->dev_kobj);
res = scst_sysfs_queue_wait_work(work);
if (res)
goto out;
res = count;
out:
kfree(arg);
TRACE_EXIT_RES(res);
return res;
}
static ssize_t vdev_sysfs_cluster_mode_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{