| Message ID | 1452888772-15097-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c index 53a7d58..4479e90 100644 --- a/drivers/md/dm-thin-metadata.c +++ b/drivers/md/dm-thin-metadata.c @@ -1203,6 +1203,12 @@ static int __reserve_metadata_snap(struct dm_pool_metadata *pmd) dm_block_t held_root; /* + * We commit to ensure the btree roots which we increment in a + * moment are up to date. + */ + __commit_transaction(pmd); + + /* * Copy the superblock. */ dm_sm_inc_block(pmd->metadata_sm, THIN_SUPERBLOCK_LOCATION);
This is a note to let you know that I have just added a patch titled dm thin metadata: fix bug when taking a metadata snapshot to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt2. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From dd3b076fda1fa10636a0b6d9f57639f74382d1c2 Mon Sep 17 00:00:00 2001 From: Joe Thornber <ejt@redhat.com> Date: Wed, 9 Dec 2015 16:23:24 +0000 Subject: dm thin metadata: fix bug when taking a metadata snapshot commit 49e99fc717f624aa75ca755d6e7bc029efd3f0e9 upstream. When you take a metadata snapshot the btree roots for the mapping and details tree need to have their reference counts incremented so they persist for the lifetime of the metadata snap. The roots being incremented were those currently written in the superblock, which could possibly be out of date if concurrent IO is triggering new mappings, breaking of sharing, etc. Fix this by performing a commit with the metadata lock held while taking a metadata snapshot. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/md/dm-thin-metadata.c | 6 ++++++ 1 file changed, 6 insertions(+) -- 1.9.1