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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.h
parentcd634fb6eec72ef8e6dd677546b8d0ffdd2501eb (diff)
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.h')
-rw-r--r--fs/ceph/mds_client.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 4e3a9cc0bba6..7d8a0d662d56 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -278,6 +278,7 @@ struct ceph_mds_client {
u64 cap_flush_seq;
struct list_head cap_dirty; /* inodes with dirty caps */
+ struct list_head cap_dirty_migrating; /* ...that are migration... */
int num_cap_flushing; /* # caps we are flushing */
spinlock_t cap_dirty_lock; /* protects above items */
wait_queue_head_t cap_flushing_wq;