8 files changed, 236 insertions, 105 deletions

diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 717d6e4e18d3..6f07ec1c2f58 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -256,6 +256,21 @@ config BLK_DEV_LOOP
 
           Most users will answer N here.
 
+config BLK_DEV_LOOP_MIN_COUNT
+        int "Number of loop devices to pre-create at init time"
+        depends on BLK_DEV_LOOP
+        default 8
+        help
+          Static number of loop devices to be unconditionally pre-created
+          at init time.
+
+          This default value can be overwritten on the kernel command
+          line or with module-parameter loop.max_loop.
+
+          The historic default is 8. If a late 2011 version of losetup(8)
+          is used, it can be set to 0, since needed loop devices can be
+          dynamically allocated with the /dev/loop-control interface.
+
 config BLK_DEV_CRYPTOLOOP
         tristate "Cryptoloop Support"
         select CRYPTO
@@ -471,7 +486,7 @@ config XEN_BLKDEV_FRONTEND
           in another domain which drives the actual block device.
 
 config XEN_BLKDEV_BACKEND
-        tristate "Block-device backend driver"
+        tristate "Xen block-device backend driver"
         depends on XEN_BACKEND
         help
           The block-device backend driver allows the kernel to export its
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 515bcd948a43..0feab261e295 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1829,10 +1829,10 @@ static int drbd_nl_syncer_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *n
 
         /* silently ignore cpu mask on UP kernel */
         if (nr_cpu_ids > 1 && sc.cpu_mask[0] != 0) {
-                err = __bitmap_parse(sc.cpu_mask, 32, 0,
+                err = bitmap_parse(sc.cpu_mask, 32,
                                 cpumask_bits(new_cpu_mask), nr_cpu_ids);
                 if (err) {
-                        dev_warn(DEV, "__bitmap_parse() failed with %d\n", err);
+                        dev_warn(DEV, "bitmap_parse() failed with %d\n", err);
                         retcode = ERR_CPU_MASK_PARSE;
                         goto fail;
                 }
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 98de8f418676..9955a53733b2 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4250,7 +4250,7 @@ static int __init floppy_init(void)
         use_virtual_dma = can_use_virtual_dma & 1;
         fdc_state[0].address = FDC1;
         if (fdc_state[0].address == -1) {
-                del_timer(&fd_timeout);
+                del_timer_sync(&fd_timeout);
                 err = -ENODEV;
                 goto out_unreg_region;
         }
@@ -4261,7 +4261,7 @@ static int __init floppy_init(void)
         fdc = 0;                /* reset fdc in case of unexpected interrupt */
         err = floppy_grab_irq_and_dma();
         if (err) {
-                del_timer(&fd_timeout);
+                del_timer_sync(&fd_timeout);
                 err = -EBUSY;
                 goto out_unreg_region;
         }
@@ -4318,7 +4318,7 @@ static int __init floppy_init(void)
                 user_reset_fdc(-1, FD_RESET_ALWAYS, false);
         }
         fdc = 0;
-        del_timer(&fd_timeout);
+        del_timer_sync(&fd_timeout);
         current_drive = 0;
         initialized = true;
         if (have_no_fdc) {
@@ -4368,7 +4368,7 @@ out_unreg_blkdev:
         unregister_blkdev(FLOPPY_MAJOR, "fd");
 out_put_disk:
         while (dr--) {
-                del_timer(&motor_off_timer[dr]);
+                del_timer_sync(&motor_off_timer[dr]);
                 if (disks[dr]->queue)
                         blk_cleanup_queue(disks[dr]->queue);
                 put_disk(disks[dr]);
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 8360239d553c..157ddcb9d0a5 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -75,11 +75,11 @@
 #include <linux/kthread.h>
 #include <linux/splice.h>
 #include <linux/sysfs.h>
-
+#include <linux/miscdevice.h>
 #include <asm/uaccess.h>
 
-static LIST_HEAD(loop_devices);
-static DEFINE_MUTEX(loop_devices_mutex);
+static DEFINE_IDR(loop_index_idr);
+static DEFINE_MUTEX(loop_index_mutex);
 
 static int max_part;
 static int part_shift;
@@ -721,17 +721,10 @@ static inline int is_loop_device(struct file *file)
 static ssize_t loop_attr_show(struct device *dev, char *page,
                               ssize_t (*callback)(struct loop_device *, char *))
 {
-        struct loop_device *l, *lo = NULL;
-
-        mutex_lock(&loop_devices_mutex);
-        list_for_each_entry(l, &loop_devices, lo_list)
-                if (disk_to_dev(l->lo_disk) == dev) {
-                        lo = l;
-                        break;
-                }
-        mutex_unlock(&loop_devices_mutex);
+        struct gendisk *disk = dev_to_disk(dev);
+        struct loop_device *lo = disk->private_data;
 
-        return lo ? callback(lo, page) : -EIO;
+        return callback(lo, page);
 }
 
 #define LOOP_ATTR_RO(_name)                                             \
@@ -749,10 +742,10 @@ static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
         ssize_t ret;
         char *p = NULL;
 
-        mutex_lock(&lo->lo_ctl_mutex);
+        spin_lock_irq(&lo->lo_lock);
         if (lo->lo_backing_file)
                 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
-        mutex_unlock(&lo->lo_ctl_mutex);
+        spin_unlock_irq(&lo->lo_lock);
 
         if (IS_ERR_OR_NULL(p))
                 ret = PTR_ERR(p);
@@ -1006,7 +999,9 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
 
         kthread_stop(lo->lo_thread);
 
+        spin_lock_irq(&lo->lo_lock);
         lo->lo_backing_file = NULL;
+        spin_unlock_irq(&lo->lo_lock);
 
         loop_release_xfer(lo);
         lo->transfer = NULL;
@@ -1484,13 +1479,22 @@ static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
 
 static int lo_open(struct block_device *bdev, fmode_t mode)
 {
-        struct loop_device *lo = bdev->bd_disk->private_data;
+        struct loop_device *lo;
+        int err = 0;
+
+        mutex_lock(&loop_index_mutex);
+        lo = bdev->bd_disk->private_data;
+        if (!lo) {
+                err = -ENXIO;
+                goto out;
+        }
 
         mutex_lock(&lo->lo_ctl_mutex);
         lo->lo_refcnt++;
         mutex_unlock(&lo->lo_ctl_mutex);
-
-        return 0;
+out:
+        mutex_unlock(&loop_index_mutex);
+        return err;
 }
 
 static int lo_release(struct gendisk *disk, fmode_t mode)
@@ -1556,40 +1560,71 @@ int loop_register_transfer(struct loop_func_table *funcs)
         return 0;
 }
 
+static int unregister_transfer_cb(int id, void *ptr, void *data)
+{
+        struct loop_device *lo = ptr;
+        struct loop_func_table *xfer = data;
+
+        mutex_lock(&lo->lo_ctl_mutex);
+        if (lo->lo_encryption == xfer)
+                loop_release_xfer(lo);
+        mutex_unlock(&lo->lo_ctl_mutex);
+        return 0;
+}
+
 int loop_unregister_transfer(int number)
 {
         unsigned int n = number;
-        struct loop_device *lo;
         struct loop_func_table *xfer;
 
         if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
                 return -EINVAL;
 
         xfer_funcs[n] = NULL;
-
-        list_for_each_entry(lo, &loop_devices, lo_list) {
-                mutex_lock(&lo->lo_ctl_mutex);
-
-                if (lo->lo_encryption == xfer)
-                        loop_release_xfer(lo);
-
-                mutex_unlock(&lo->lo_ctl_mutex);
-        }
-
+        idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
         return 0;
 }
 
 EXPORT_SYMBOL(loop_register_transfer);
 EXPORT_SYMBOL(loop_unregister_transfer);
 
-static struct loop_device *loop_alloc(int i)
+static int loop_add(struct loop_device **l, int i)
 {
         struct loop_device *lo;
         struct gendisk *disk;
+        int err;
 
         lo = kzalloc(sizeof(*lo), GFP_KERNEL);
-        if (!lo)
+        if (!lo) {
+                err = -ENOMEM;
                 goto out;
+        }
+
+        err = idr_pre_get(&loop_index_idr, GFP_KERNEL);
+        if (err < 0)
+                goto out_free_dev;
+
+        if (i >= 0) {
+                int m;
+
+                /* create specific i in the index */
+                err = idr_get_new_above(&loop_index_idr, lo, i, &m);
+                if (err >= 0 && i != m) {
+                        idr_remove(&loop_index_idr, m);
+                        err = -EEXIST;
+                }
+        } else if (i == -1) {
+                int m;
+
+                /* get next free nr */
+                err = idr_get_new(&loop_index_idr, lo, &m);
+                if (err >= 0)
+                        i = m;
+        } else {
+                err = -EINVAL;
+        }
+        if (err < 0)
+                goto out_free_dev;
 
         lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
         if (!lo->lo_queue)
@@ -1610,81 +1645,158 @@ static struct loop_device *loop_alloc(int i)
         disk->private_data      = lo;
         disk->queue             = lo->lo_queue;
         sprintf(disk->disk_name, "loop%d", i);
-        return lo;
+        add_disk(disk);
+        *l = lo;
+        return lo->lo_number;
 
 out_free_queue:
         blk_cleanup_queue(lo->lo_queue);
 out_free_dev:
         kfree(lo);
 out:
-        return NULL;
+        return err;
 }
 
-static void loop_free(struct loop_device *lo)
+static void loop_remove(struct loop_device *lo)
 {
+        del_gendisk(lo->lo_disk);
         blk_cleanup_queue(lo->lo_queue);
         put_disk(lo->lo_disk);
-        list_del(&lo->lo_list);
         kfree(lo);
 }
 
-static struct loop_device *loop_init_one(int i)
+static int find_free_cb(int id, void *ptr, void *data)
+{
+        struct loop_device *lo = ptr;
+        struct loop_device **l = data;
+
+        if (lo->lo_state == Lo_unbound) {
+                *l = lo;
+                return 1;
+        }
+        return 0;
+}
+
+static int loop_lookup(struct loop_device **l, int i)
 {
         struct loop_device *lo;
+        int ret = -ENODEV;
 
-        list_for_each_entry(lo, &loop_devices, lo_list) {
-                if (lo->lo_number == i)
-                        return lo;
+        if (i < 0) {
+                int err;
+
+                err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
+                if (err == 1) {
+                        *l = lo;
+                        ret = lo->lo_number;
+                }
+                goto out;
         }
 
-        lo = loop_alloc(i);
+        /* lookup and return a specific i */
+        lo = idr_find(&loop_index_idr, i);
         if (lo) {
-                add_disk(lo->lo_disk);
-                list_add_tail(&lo->lo_list, &loop_devices);
+                *l = lo;
+                ret = lo->lo_number;
         }
-        return lo;
-}
-
-static void loop_del_one(struct loop_device *lo)
-{
-        del_gendisk(lo->lo_disk);
-        loop_free(lo);
+out:
+        return ret;
 }
 
 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
 {
         struct loop_device *lo;
         struct kobject *kobj;
+        int err;
 
-        mutex_lock(&loop_devices_mutex);
-        lo = loop_init_one(MINOR(dev) >> part_shift);
-        kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM);
-        mutex_unlock(&loop_devices_mutex);
+        mutex_lock(&loop_index_mutex);
+        err = loop_lookup(&lo, MINOR(dev) >> part_shift);
+        if (err < 0)
+                err = loop_add(&lo, MINOR(dev) >> part_shift);
+        if (err < 0)
+                kobj = ERR_PTR(err);
+        else
+                kobj = get_disk(lo->lo_disk);
+        mutex_unlock(&loop_index_mutex);
 
         *part = 0;
         return kobj;
 }
 
+static long loop_control_ioctl(struct file *file, unsigned int cmd,
+                               unsigned long parm)
+{
+        struct loop_device *lo;
+        int ret = -ENOSYS;
+
+        mutex_lock(&loop_index_mutex);
+        switch (cmd) {
+        case LOOP_CTL_ADD:
+                ret = loop_lookup(&lo, parm);
+                if (ret >= 0) {
+                        ret = -EEXIST;
+                        break;
+                }
+                ret = loop_add(&lo, parm);
+                break;
+        case LOOP_CTL_REMOVE:
+                ret = loop_lookup(&lo, parm);
+                if (ret < 0)
+                        break;
+                mutex_lock(&lo->lo_ctl_mutex);
+                if (lo->lo_state != Lo_unbound) {
+                        ret = -EBUSY;
+                        mutex_unlock(&lo->lo_ctl_mutex);
+                        break;
+                }
+                if (lo->lo_refcnt > 0) {
+                        ret = -EBUSY;
+                        mutex_unlock(&lo->lo_ctl_mutex);
+                        break;
+                }
+                lo->lo_disk->private_data = NULL;
+                mutex_unlock(&lo->lo_ctl_mutex);
+                idr_remove(&loop_index_idr, lo->lo_number);
+                loop_remove(lo);
+                break;
+        case LOOP_CTL_GET_FREE:
+                ret = loop_lookup(&lo, -1);
+                if (ret >= 0)
+                        break;
+                ret = loop_add(&lo, -1);
+        }
+        mutex_unlock(&loop_index_mutex);
+
+        return ret;
+}
+
+static const struct file_operations loop_ctl_fops = {
+        .open           = nonseekable_open,
+        .unlocked_ioctl = loop_control_ioctl,
+        .compat_ioctl   = loop_control_ioctl,
+        .owner          = THIS_MODULE,
+        .llseek         = noop_llseek,
+};
+
+static struct miscdevice loop_misc = {
+        .minor          = LOOP_CTRL_MINOR,
+        .name           = "loop-control",
+        .fops           = &loop_ctl_fops,
+};
+
+MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
+MODULE_ALIAS("devname:loop-control");
+
 static int __init loop_init(void)
 {
         int i, nr;
         unsigned long range;
-        struct loop_device *lo, *next;
+        struct loop_device *lo;
+        int err;
 
-        /*
-         * loop module now has a feature to instantiate underlying device
-         * structure on-demand, provided that there is an access dev node.
-         * However, this will not work well with user space tool that doesn't
-         * know about such "feature".  In order to not break any existing
-         * tool, we do the following:
-         *
-         * (1) if max_loop is specified, create that many upfront, and this
-         *     also becomes a hard limit.
-         * (2) if max_loop is not specified, create 8 loop device on module
-         *     load, user can further extend loop device by create dev node
-         *     themselves and have kernel automatically instantiate actual
-         *     device on-demand.
-         */
+        err = misc_register(&loop_misc);
+        if (err < 0)
+                return err;
 
         part_shift = 0;
         if (max_part > 0) {
@@ -1707,57 +1819,60 @@ static int __init loop_init(void)
         if (max_loop > 1UL << (MINORBITS - part_shift))
                 return -EINVAL;
 
+        /*
+         * If max_loop is specified, create that many devices upfront.
+         * This also becomes a hard limit. If max_loop is not specified,
+         * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
+         * init time. Loop devices can be requested on-demand with the
+         * /dev/loop-control interface, or be instantiated by accessing
+         * a 'dead' device node.
+         */
         if (max_loop) {
                 nr = max_loop;
                 range = max_loop << part_shift;
         } else {
-                nr = 8;
+                nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
                 range = 1UL << MINORBITS;
         }
 
         if (register_blkdev(LOOP_MAJOR, "loop"))
                 return -EIO;
 
-        for (i = 0; i < nr; i++) {
-                lo = loop_alloc(i);
-                if (!lo)
-                        goto Enomem;
-                list_add_tail(&lo->lo_list, &loop_devices);
-        }
-
-        /* point of no return */
-
-        list_for_each_entry(lo, &loop_devices, lo_list)
-                add_disk(lo->lo_disk);
-
         blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
                                   THIS_MODULE, loop_probe, NULL, NULL);
 
+        /* pre-create number of devices given by config or max_loop */
+        mutex_lock(&loop_index_mutex);
+        for (i = 0; i < nr; i++)
+                loop_add(&lo, i);
+        mutex_unlock(&loop_index_mutex);
+
         printk(KERN_INFO "loop: module loaded\n");
         return 0;
+}
 
-Enomem:
-        printk(KERN_INFO "loop: out of memory\n");
-
-        list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
-                loop_free(lo);
+static int loop_exit_cb(int id, void *ptr, void *data)
+{
+        struct loop_device *lo = ptr;
 
-        unregister_blkdev(LOOP_MAJOR, "loop");
-        return -ENOMEM;
+        loop_remove(lo);
+        return 0;
 }
 
 static void __exit loop_exit(void)
 {
         unsigned long range;
-        struct loop_device *lo, *next;
 
         range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
 
-        list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
-                loop_del_one(lo);
+        idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
+        idr_remove_all(&loop_index_idr);
+        idr_destroy(&loop_index_idr);
 
         blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
         unregister_blkdev(LOOP_MAJOR, "loop");
+
+        misc_deregister(&loop_misc);
 }
 
 module_init(loop_init);
diff --git a/drivers/block/swim3.c b/drivers/block/swim3.c
index 773bfa792777..ae3e167e17ad 100644
--- a/drivers/block/swim3.c
+++ b/drivers/block/swim3.c
@@ -1184,6 +1184,7 @@ static struct of_device_id swim3_match[] =
         {
         .compatible     = "swim3"
         },
+        { /* end of list */ }
 };
 
 static struct macio_driver swim3_driver =
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 9e40b283a468..00c57c90e2d6 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -46,7 +46,7 @@
 
 #define DRV_PFX "xen-blkback:"
 #define DPRINTK(fmt, args...)                           \
-        pr_debug(DRV_PFX "(%s:%d) " fmt ".\n",  \
+        pr_debug(DRV_PFX "(%s:%d) " fmt ".\n",          \
                  __func__, __LINE__, ##args)
 
 
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 3f129b45451a..5fd2010f7d2b 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -590,7 +590,7 @@ static void frontend_changed(struct xenbus_device *dev,
 
                 /*
                  * Enforce precondition before potential leak point.
-                 * blkif_disconnect() is idempotent.
+                 * xen_blkif_disconnect() is idempotent.
                  */
                 xen_blkif_disconnect(be->blkif);
 
@@ -601,17 +601,17 @@ static void frontend_changed(struct xenbus_device *dev,
                 break;
 
         case XenbusStateClosing:
-                xen_blkif_disconnect(be->blkif);
                 xenbus_switch_state(dev, XenbusStateClosing);
                 break;
 
         case XenbusStateClosed:
+                xen_blkif_disconnect(be->blkif);
                 xenbus_switch_state(dev, XenbusStateClosed);
                 if (xenbus_dev_is_online(dev))
                         break;
                 /* fall through if not online */
         case XenbusStateUnknown:
-                /* implies blkif_disconnect() via blkback_remove() */
+                /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
                 device_unregister(&dev->dev);
                 break;
 
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index b536a9cef917..9ea8c2576c70 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -123,8 +123,8 @@ static DEFINE_SPINLOCK(minor_lock);
 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
-#define EMULATED_SD_DISK_MINOR_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET + (4 * 16))
-#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_HD_DISK_NAME_OFFSET + 4)
+#define EMULATED_SD_DISK_MINOR_OFFSET (0)
+#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 
 #define DEV_NAME        "xvd"   /* name in /dev */
 
@@ -529,7 +529,7 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
                 minor = BLKIF_MINOR_EXT(info->vdevice);
                 nr_parts = PARTS_PER_EXT_DISK;
                 offset = minor / nr_parts;
-                if (xen_hvm_domain() && offset <= EMULATED_HD_DISK_NAME_OFFSET + 4)
+                if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
                                         "emulated IDE disks,\n\t choose an xvd device name"
                                         "from xvde on\n", info->vdevice);