# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1263811603 0
# Node ID 3358caa6b3a3c68845a4e4aa2c8b44e7641cb243
# Parent 6d6c3dd995c07527b94d5278b0df4f5252888ccd
xen/blkfront: fixes for 'xm block-detach ... --force'
Prevent prematurely freeing 'struct blkfront_info' instances (when the
xenbus data structures are gone, but the Linux ones are still needed).
Prevent adding a disk with the same (major, minor) [and hence the same
name and sysfs entries, which leads to oopses] when the previous
instance wasn't fully de-allocated yet.
This still doesn't address all issues resulting from forced detach:
I/O submitted after the detach still blocks forever, likely preventing
subsequent un-mounting from completing. It's not clear to me (not
knowing much about the block layer) how this can be avoided.
This also doesn't address issues with duplicate device creation caused
by re-using the hdXX and sdXX name spaces - this would require
synchronization with the respective native code.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
drivers/xen/blkfront/blkfront.c | 15 ++++-
drivers/xen/blkfront/block.h | 1
drivers/xen/blkfront/vbd.c | 105 ++++++++++++++++++++++++++++++++++++++--
3 files changed, 115 insertions(+), 6 deletions(-)
diff -r 6d6c3dd995c0 -r 3358caa6b3a3 drivers/xen/blkfront/blkfront.c
--- a/drivers/xen/blkfront/blkfront.c Wed Jan 13 08:11:51 2010 +0000
+++ b/drivers/xen/blkfront/blkfront.c Mon Jan 18 10:46:43 2010 +0000
@@ -418,7 +418,10 @@ static int blkfront_remove(struct xenbus
blkif_free(info, 0);
- kfree(info);
+ if(info->users == 0)
+ kfree(info);
+ else
+ info->is_ready = -1;
return 0;
}
@@ -480,6 +483,9 @@ int blkif_open(struct inode *inode, stru
int blkif_open(struct inode *inode, struct file *filep)
{
struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
+
+ if(info->is_ready < 0)
+ return -ENODEV;
info->users++;
return 0;
}
@@ -496,7 +502,10 @@ int blkif_release(struct inode *inode, s
struct xenbus_device * dev = info->xbdev;
enum xenbus_state state =
xenbus_read_driver_state(dev->otherend);
- if (state == XenbusStateClosing && info->is_ready)
+ if(info->is_ready < 0) {
+ blkfront_closing(dev);
+ kfree(info);
+ } else if (state == XenbusStateClosing && info->is_ready)
blkfront_closing(dev);
}
return 0;
@@ -887,7 +896,7 @@ int blkfront_is_ready(struct xenbus_devi
{
struct blkfront_info *info = dev->dev.driver_data;
- return info->is_ready;
+ return info->is_ready > 0;
}
diff -r 6d6c3dd995c0 -r 3358caa6b3a3 drivers/xen/blkfront/block.h
--- a/drivers/xen/blkfront/block.h Wed Jan 13 08:11:51 2010 +0000
+++ b/drivers/xen/blkfront/block.h Mon Jan 18 10:46:43 2010 +0000
@@ -78,6 +78,7 @@ struct xlbd_major_info
int index;
int usage;
struct xlbd_type_info *type;
+ struct xlbd_minor_state *minors;
};
struct blk_shadow {
diff -r 6d6c3dd995c0 -r 3358caa6b3a3 drivers/xen/blkfront/vbd.c
--- a/drivers/xen/blkfront/vbd.c Wed Jan 13 08:11:51 2010 +0000
+++ b/drivers/xen/blkfront/vbd.c Mon Jan 18 10:46:43 2010 +0000
@@ -48,6 +48,12 @@
#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
+struct xlbd_minor_state {
+ unsigned int nr;
+ unsigned long *bitmap;
+ spinlock_t lock;
+};
+
/*
* For convenience we distinguish between ide, scsi and 'other' (i.e.,
* potentially combinations of the two) in the naming scheme and in a few other
@@ -96,6 +102,8 @@ static struct xlbd_major_info *major_inf
#define XLBD_MAJOR_IDE_RANGE XLBD_MAJOR_IDE_START ... XLBD_MAJOR_SCSI_START
- 1
#define XLBD_MAJOR_SCSI_RANGE XLBD_MAJOR_SCSI_START ... XLBD_MAJOR_VBD_START
- 1
#define XLBD_MAJOR_VBD_RANGE XLBD_MAJOR_VBD_START ... XLBD_MAJOR_VBD_START +
NUM_VBD_MAJORS - 1
+
+#define XLBD_MAJOR_VBD_ALT(idx) ((idx) ^ XLBD_MAJOR_VBD_START ^
(XLBD_MAJOR_VBD_START + 1))
static struct block_device_operations xlvbd_block_fops =
{
@@ -114,6 +122,7 @@ xlbd_alloc_major_info(int major, int min
xlbd_alloc_major_info(int major, int minor, int index)
{
struct xlbd_major_info *ptr;
+ struct xlbd_minor_state *minors;
int do_register;
ptr = kzalloc(sizeof(struct xlbd_major_info), GFP_KERNEL);
@@ -121,6 +130,22 @@ xlbd_alloc_major_info(int major, int min
return NULL;
ptr->major = major;
+ minors = kmalloc(sizeof(*minors), GFP_KERNEL);
+ if (minors == NULL) {
+ kfree(ptr);
+ return NULL;
+ }
+
+ minors->bitmap = kzalloc(BITS_TO_LONGS(256) * sizeof(*minors->bitmap),
+ GFP_KERNEL);
+ if (minors->bitmap == NULL) {
+ kfree(minors);
+ kfree(ptr);
+ return NULL;
+ }
+
+ spin_lock_init(&minors->lock);
+ minors->nr = 256;
do_register = 1;
switch (index) {
@@ -143,13 +168,19 @@ xlbd_alloc_major_info(int major, int min
* if someone already registered block major 202,
* don't try to register it again
*/
- if (major_info[XLBD_MAJOR_VBD_START] != NULL)
+ if (major_info[XLBD_MAJOR_VBD_ALT(index)] != NULL) {
+ kfree(minors->bitmap);
+ kfree(minors);
+ minors = major_info[XLBD_MAJOR_VBD_ALT(index)]->minors;
do_register = 0;
+ }
break;
}
if (do_register) {
if (register_blkdev(ptr->major, ptr->type->devname)) {
+ kfree(minors->bitmap);
+ kfree(minors);
kfree(ptr);
return NULL;
}
@@ -157,6 +188,7 @@ xlbd_alloc_major_info(int major, int min
printk("xen-vbd: registered block device major %i\n",
ptr->major);
}
+ ptr->minors = minors;
major_info[index] = ptr;
return ptr;
}
@@ -209,6 +241,61 @@ xlbd_put_major_info(struct xlbd_major_in
}
static int
+xlbd_reserve_minors(struct xlbd_major_info *mi, unsigned int minor,
+ unsigned int nr_minors)
+{
+ struct xlbd_minor_state *ms = mi->minors;
+ unsigned int end = minor + nr_minors;
+ int rc;
+
+ if (end > ms->nr) {
+ unsigned long *bitmap, *old;
+
+ bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
+ GFP_KERNEL);
+ if (bitmap == NULL)
+ return -ENOMEM;
+
+ spin_lock(&ms->lock);
+ if (end > ms->nr) {
+ old = ms->bitmap;
+ memcpy(bitmap, ms->bitmap,
+ BITS_TO_LONGS(ms->nr) * sizeof(*bitmap));
+ ms->bitmap = bitmap;
+ ms->nr = BITS_TO_LONGS(end) * BITS_PER_LONG;
+ } else
+ old = bitmap;
+ spin_unlock(&ms->lock);
+ kfree(old);
+ }
+
+ spin_lock(&ms->lock);
+ if (find_next_bit(ms->bitmap, end, minor) >= end) {
+ for (; minor < end; ++minor)
+ __set_bit(minor, ms->bitmap);
+ rc = 0;
+ } else
+ rc = -EBUSY;
+ spin_unlock(&ms->lock);
+
+ return rc;
+}
+
+static void
+xlbd_release_minors(struct xlbd_major_info *mi, unsigned int minor,
+ unsigned int nr_minors)
+{
+ struct xlbd_minor_state *ms = mi->minors;
+ unsigned int end = minor + nr_minors;
+
+ BUG_ON(end > ms->nr);
+ spin_lock(&ms->lock);
+ for (; minor < end; ++minor)
+ __clear_bit(minor, ms->bitmap);
+ spin_unlock(&ms->lock);
+}
+
+static int
xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
{
request_queue_t *rq;
@@ -263,9 +350,14 @@ xlvbd_alloc_gendisk(int major, int minor
if ((minor & ((1 << mi->type->partn_shift) - 1)) == 0)
nr_minors = 1 << mi->type->partn_shift;
+ err = xlbd_reserve_minors(mi, minor, nr_minors);
+ if (err)
+ goto out;
+ err = -ENODEV;
+
gd = alloc_disk(nr_minors);
if (gd == NULL)
- goto out;
+ goto release;
offset = mi->index * mi->type->disks_per_major +
(minor >> mi->type->partn_shift);
@@ -304,7 +396,7 @@ xlvbd_alloc_gendisk(int major, int minor
if (xlvbd_init_blk_queue(gd, sector_size)) {
del_gendisk(gd);
- goto out;
+ goto release;
}
info->rq = gd->queue;
@@ -324,6 +416,8 @@ xlvbd_alloc_gendisk(int major, int minor
return 0;
+ release:
+ xlbd_release_minors(mi, minor, nr_minors);
out:
if (mi)
xlbd_put_major_info(mi);
@@ -369,14 +463,19 @@ void
void
xlvbd_del(struct blkfront_info *info)
{
+ unsigned int minor, nr_minors;
+
if (info->mi == NULL)
return;
BUG_ON(info->gd == NULL);
+ minor = info->gd->first_minor;
+ nr_minors = info->gd->minors;
del_gendisk(info->gd);
put_disk(info->gd);
info->gd = NULL;
+ xlbd_release_minors(info->mi, minor, nr_minors);
xlbd_put_major_info(info->mi);
info->mi = NULL;
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