linux/drivers/block, branch v3.10.37

mm: close PageTail race

2014-04-03T19:01:05Z

commit 668f9abbd4334e6c29fa8acd71635c4f9101caa7 upstream. Commit bf6bddf1924e ("mm: introduce compaction and migration for ballooned pages") introduces page_count(page) into memory compaction which dereferences page->first_page if PageTail(page). This results in a very rare NULL pointer dereference on the aforementioned page_count(page). Indeed, anything that does compound_head(), including page_count() is susceptible to racing with prep_compound_page() and seeing a NULL or dangling page->first_page pointer. This patch uses Andrea's implementation of compound_trans_head() that deals with such a race and makes it the default compound_head() implementation. This includes a read memory barrier that ensures that if PageTail(head) is true that we return a head page that is neither NULL nor dangling. The patch then adds a store memory barrier to prep_compound_page() to ensure page->first_page is set. This is the safest way to ensure we see the head page that we are expecting, PageTail(page) is already in the unlikely() path and the memory barriers are unfortunately required. Hugetlbfs is the exception, we don't enforce a store memory barrier during init since no race is possible. Signed-off-by: David Rientjes Cc: Holger Kiehl Cc: Christoph Lameter Cc: Rafael Aquini Cc: Vlastimil Babka Cc: Michal Hocko Cc: Mel Gorman Cc: Andrea Arcangeli Cc: Rik van Riel Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

xen-blkfront: handle backend CLOSED without CLOSING

2014-02-22T20:41:25Z

commit 3661371701e714f0cea4120f6a365340858fb4e4 upstream. Backend drivers shouldn't transistion to CLOSED unless the frontend is CLOSED. If a backend does transition to CLOSED too soon then the frontend may not see the CLOSING state and will not properly shutdown. So, treat an unexpected backend CLOSED state the same as CLOSING. Signed-off-by: David Vrabel Acked-by: Konrad Rzeszutek Wilk Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman

rbd: fix error handling from rbd_snap_name()

2014-01-09T20:24:26Z

commit da6a6b63978d45f9ae582d1f362f182012da3a22 upstream. rbd_snap_name() calls rbd_dev_v{1,2}_snap_name() depending on the format of the image. The format 1 version returns NULL on error, which is handled by the caller. The format 2 version returns an ERR_PTR, which the caller of rbd_snap_name() does not expect. Fortunately this is unlikely to occur in practice because rbd_snap_id_by_name() is called before rbd_snap_name(). This would hit similar errors to rbd_snap_name() (like the snapshot not existing) and return early, so rbd_snap_name() would not hit an error unless the snapshot was removed between the two calls or memory was exhausted. Use an ERR_PTR in rbd_dev_v1_snap_name() so that the specific error can be propagated, and it is consistent with rbd_dev_v2_snap_name(). Handle the ERR_PTR in the only rbd_snap_name() caller. Suggested-by: Alex Elder Signed-off-by: Josh Durgin Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman

rbd: ignore unmapped snapshots that no longer exist

2014-01-09T20:24:26Z

commit efadc98aab674153709cc357ba565f04e3164fcd upstream. This prevents erroring out while adding a device when a snapshot unrelated to the current mapping is deleted between reading the snapshot context and reading the snapshot names. If the mapped snapshot name is not found an error still occurs as usual. Signed-off-by: Josh Durgin Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman

rbd: fix use-after free of rbd_dev->disk

2014-01-09T20:24:26Z

commit 9875201e10496612080e7d164acc8f625c18725c upstream. Removing a device deallocates the disk, unschedules the watch, and finally cleans up the rbd_dev structure. rbd_dev_refresh(), called from the watch callback, updates the disk size and rbd_dev structure. With no locking between them, rbd_dev_refresh() may use the device or rbd_dev after they've been freed. To fix this, check whether RBD_DEV_FLAG_REMOVING is set before updating the disk size in rbd_dev_refresh(). In order to prevent a race where rbd_dev_refresh() is already revalidating the disk when rbd_remove() is called, move the call to rbd_bus_del_dev() after the watch is unregistered and all notifies are complete. It's safe to defer deleting this structure because no new requests can be submitted once the RBD_DEV_FLAG_REMOVING is set, since the device cannot be opened. Fixes: http://tracker.ceph.com/issues/5636 Signed-off-by: Josh Durgin Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman

rbd: make rbd_obj_notify_ack() synchronous

2014-01-09T20:24:26Z

commit 20e0af67ce88c657d0601977b9941a2256afbdaa upstream. The only user of rbd_obj_notify_ack() is rbd_watch_cb(). It used asynchronously with no tracking of when the notify ack completes, so it may still be in progress when the osd_client is shut down. This results in a BUG() since the osd client assumes no requests are in flight when it stops. Since all notifies are flushed before the osd_client is stopped, waiting for the notify ack to complete before returning from the watch callback ensures there are no notify acks in flight during shutdown. Rename rbd_obj_notify_ack() to rbd_obj_notify_ack_sync() to reflect its new synchronous nature. Signed-off-by: Josh Durgin Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman

rbd: complete notifies before cleaning up osd_client and rbd_dev

2014-01-09T20:24:26Z

commit 9abc59908e0c5f983aaa91150da32d5b62cf60b7 upstream. To ensure rbd_dev is not used after it's released, flush all pending notify callbacks before calling rbd_dev_image_release(). No new notifies can be added to the queue at this point because the watch has already be unregistered with the osd_client. Signed-off-by: Josh Durgin Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman

rbd: fix null dereference in dout

2014-01-09T20:24:26Z

commit c35455791c1131e7ccbf56ea6fbdd562401c2ce2 upstream. The order parameter is sometimes NULL in _rbd_dev_v2_snap_size(), but the dout() always derefences it. Move this to another dout() protected by a check that order is non-NULL. Signed-off-by: Josh Durgin Reviewed-by: Sage Weil Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman

rbd: fix buffer size for writes to images with snapshots

2014-01-09T20:24:25Z

commit 03507db631c94a48e316c7f638ffb2991544d617 upstream. rbd_osd_req_create() needs to know the snapshot context size to create a buffer large enough to send it with the message front. It gets this from the img_request, which was not set for the obj_request yet. This resulted in trying to write past the end of the front payload, hitting this BUG: libceph: BUG_ON(p > msg->front.iov_base + msg->front.iov_len); Fix this by associating the obj_request with its img_request immediately after it's created, before the osd request is created. Fixes: http://tracker.ceph.com/issues/5760 Suggested-by: Alex Elder Signed-off-by: Josh Durgin Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman

rbd: fix a couple warnings

2014-01-09T20:24:25Z

commit e976cad0f0dbe5440a4ca38e29e1f932d9319125 upstream. gcc isn't quite smart enough and generates these warnings: drivers/block/rbd.c: In function 'rbd_img_request_fill': drivers/block/rbd.c:1266:22: warning: 'bio_list' may be used uninitialized in this function [-Wmaybe-uninitialized] drivers/block/rbd.c:2186:14: note: 'bio_list' was declared here drivers/block/rbd.c:2247:10: warning: 'pages' may be used uninitialized in this function [-Wmaybe-uninitialized] even though they are initialized for their respective code paths. Signed-off-by: Sage Weil Signed-off-by: Greg Kroah-Hartman