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authorSage Weil <sage@newdream.net>2011-05-24 11:46:31 -0700
committerSage Weil <sage@newdream.net>2011-05-24 11:52:12 -0700
commitdb3540522e955c1ebb391f4f5324dff4f20ecd09 (patch)
tree8c25b07caa8614345c71f09e8872e60b68af4c31 /fs/ceph/mds_client.c
parentcd634fb6eec72ef8e6dd677546b8d0ffdd2501eb (diff)
downloadop-kernel-dev-db3540522e955c1ebb391f4f5324dff4f20ecd09.zip
op-kernel-dev-db3540522e955c1ebb391f4f5324dff4f20ecd09.tar.gz
ceph: fix cap flush race reentrancy
In e9964c10 we change cap flushing to do a delicate dance because some inodes on the cap_dirty list could be in a migrating state (got EXPORT but not IMPORT) in which we couldn't actually flush and move from dirty->flushing, breaking the while (!empty) { process first } loop structure. It worked for a single sync thread, but was not reentrant and triggered infinite loops when multiple syncers came along. Instead, move inodes with dirty to a separate cap_dirty_migrating list when in the limbo export-but-no-import state, allowing us to go back to the simple loop structure (which was reentrant). This is cleaner and more robust. Audited the cap_dirty users and this looks fine: list_empty(&ci->i_dirty_item) is still a reliable indicator of whether we have dirty caps (which list we're on is irrelevant) and list_del_init() calls still do the right thing. Signed-off-by: Sage Weil <sage@newdream.net>
Diffstat (limited to 'fs/ceph/mds_client.c')
-rw-r--r--fs/ceph/mds_client.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index c12d2e9..79743d1 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3004,6 +3004,7 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
spin_lock_init(&mdsc->snap_flush_lock);
mdsc->cap_flush_seq = 0;
INIT_LIST_HEAD(&mdsc->cap_dirty);
+ INIT_LIST_HEAD(&mdsc->cap_dirty_migrating);
mdsc->num_cap_flushing = 0;
spin_lock_init(&mdsc->cap_dirty_lock);
init_waitqueue_head(&mdsc->cap_flushing_wq);
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