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blkfront: Fix blkfront backend switch race (bdev open)
We need not mind if users grab a late handle on a closing disk. We probably even should not. But we have to make sure it's not a dead one already Let the bdev deal with a gendisk deleted under its feet. Takes the info mutex to decide a race against backend closing. Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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parent
b70f5fa043
commit
139617437a
1 changed files with 24 additions and 7 deletions
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@ -1118,16 +1118,33 @@ static int blkfront_is_ready(struct xenbus_device *dev)
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static int blkif_open(struct block_device *bdev, fmode_t mode)
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{
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struct blkfront_info *info = bdev->bd_disk->private_data;
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if (!info->xbdev)
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return -ENODEV;
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struct gendisk *disk = bdev->bd_disk;
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struct blkfront_info *info;
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int err = 0;
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lock_kernel();
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info->users++;
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unlock_kernel();
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return 0;
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info = disk->private_data;
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if (!info) {
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/* xbdev gone */
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err = -ERESTARTSYS;
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goto out;
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}
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mutex_lock(&info->mutex);
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if (!info->gd)
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/* xbdev is closed */
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err = -ERESTARTSYS;
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mutex_unlock(&info->mutex);
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if (!err)
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++info->users;
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unlock_kernel();
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out:
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return err;
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}
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static int blkif_release(struct gendisk *disk, fmode_t mode)
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