The commit is pushed to "branch-rh7-3.10.0-229.7.2.vz7.8.x-ovz" and will appear
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.8.4
------>
commit ec4f6defee626918fb28b89b939fd239c97e7145
Author: Maxim Patlasov <[email protected]>
Date: Thu Oct 8 18:40:43 2015 +0400
ploop: do not use fiemap beyond eof
map_extent_get_block() optimizes I/O by merging adjacent ext4 extents.
However,
it's useless to ask ext4 about layout beyond EOF because ploop always
extends
image file by fallocate() w/o FALLOC_FL_KEEP_SIZE flag.
And more than that -- it can be also dangerous because userspace merge
utility may race with us extending image file by ordinary write-s resulting
in (temporary) FIEMAP_EXTENT_DELALLOC extents.
https://jira.sw.ru/browse/PSBM-26762
https://jira.sw.ru/browse/PSBM-39251
Signed-off-by: Maxim Patlasov <[email protected]>
---
drivers/block/ploop/io_direct_map.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/block/ploop/io_direct_map.c
b/drivers/block/ploop/io_direct_map.c
index c1d889b..977adc2 100644
--- a/drivers/block/ploop/io_direct_map.c
+++ b/drivers/block/ploop/io_direct_map.c
@@ -776,6 +776,11 @@ struct extent_map *map_extent_get_block(struct ploop_io
*io,
* something bigger.
*/
do {
+ /* avoid race with userspace merge */
+ if (em->end >=
+ ((sector_t)io->alloc_head << io->plo->cluster_log))
+ break;
+
last = em->end;
extent_put(em);
em = __map_extent(io, mapping, last, len, create,
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