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xen/blkback: safely unmap purge persistent grants

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Commit c43cf3ea83 ("xen-blkback: safely unmap grants in case they
are still in use") use gnttab_unmap_refs_async() to wait until the
mapped pages are no longer in use before unmapping them, but that
commit missed the persistent case.  Purge persistent pages can't be
unmapped either unless no longer in use.

Signed-off-by: Bob Liu <bob.liu@oracle.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Bob Liu 2015-04-03 14:42:58 +08:00 committed by David Vrabel
parent b787f68c36
commit 325d73bf8f
1 changed files with 18 additions and 6 deletions
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24
drivers/block/xen-blkback/blkback.c
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@ -329,8 +329,18 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
struct persistent_gnt *persistent_gnt;
int ret, segs_to_unmap = 0;
int segs_to_unmap = 0;
struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work);
struct gntab_unmap_queue_data unmap_data;
struct completion unmap_completion;
init_completion(&unmap_completion);
unmap_data.data = &unmap_completion;
unmap_data.done = &free_persistent_gnts_unmap_callback;
unmap_data.pages = pages;
unmap_data.unmap_ops = unmap;
unmap_data.kunmap_ops = NULL;
while(!list_empty(&blkif->persistent_purge_list)) {
persistent_gnt = list_first_entry(&blkif->persistent_purge_list,
@ -346,17 +356,19 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
pages[segs_to_unmap] = persistent_gnt->page;
if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
ret = gnttab_unmap_refs(unmap, NULL, pages,
segs_to_unmap);
BUG_ON(ret);
unmap_data.count = segs_to_unmap;
gnttab_unmap_refs_async(&unmap_data);
wait_for_completion(&unmap_completion);
put_free_pages(blkif, pages, segs_to_unmap);
segs_to_unmap = 0;
}
kfree(persistent_gnt);
}
if (segs_to_unmap > 0) {
ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap);
BUG_ON(ret);
unmap_data.count = segs_to_unmap;
gnttab_unmap_refs_async(&unmap_data);
wait_for_completion(&unmap_completion);
put_free_pages(blkif, pages, segs_to_unmap);
}
}