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| author | Daniel Stodden <daniel.stodden@citrix.com> | 2010-08-07 18:36:53 +0200 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2010-08-07 18:38:43 +0200 |
| commit | 139617437aff1f0d3b57c2d7cc60e60efc8fe6c3 (patch) | |
| tree | 2c903b3f6456ab4a7d70c16c864ceb63bc366a5e /drivers/block/xen-blkfront.c | |
| parent | b70f5fa043b318659c936d8c3c696250e6528944 (diff) | |
| download | linux-139617437aff1f0d3b57c2d7cc60e60efc8fe6c3.tar.gz linux-139617437aff1f0d3b57c2d7cc60e60efc8fe6c3.tar.bz2 linux-139617437aff1f0d3b57c2d7cc60e60efc8fe6c3.zip | |
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>
Diffstat (limited to 'drivers/block/xen-blkfront.c')
| -rw-r--r-- | drivers/block/xen-blkfront.c | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 1e406f0331e7..763a315712cc 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -1118,16 +1118,33 @@ static int blkfront_is_ready(struct xenbus_device *dev) static int blkif_open(struct block_device *bdev, fmode_t mode) { - struct blkfront_info *info = bdev->bd_disk->private_data; - - if (!info->xbdev) - return -ENODEV; + struct gendisk *disk = bdev->bd_disk; + struct blkfront_info *info; + int err = 0; lock_kernel(); - info->users++; - unlock_kernel(); - return 0; + info = disk->private_data; + if (!info) { + /* xbdev gone */ + err = -ERESTARTSYS; + goto out; + } + + mutex_lock(&info->mutex); + + if (!info->gd) + /* xbdev is closed */ + err = -ERESTARTSYS; + + mutex_unlock(&info->mutex); + + if (!err) + ++info->users; + + unlock_kernel(); +out: + return err; } static int blkif_release(struct gendisk *disk, fmode_t mode) |