ceph: fix rdcache_gen usage and invalidate
We used to use rdcache_gen to indicate whether we "might" have cached
pages. Now we just look at the mapping to determine that. However, some
old behavior remains from that transition.
First, rdcache_gen == 0 no longer means we have no pages. That can happen
at any time (presumably when we carry FILE_CACHE). We should not reset it
to zero, and we should not check that it is zero.
That means that the only purpose for rdcache_revoking is to resolve races
between new issues of FILE_CACHE and an async invalidate. If they are
equal, we should invalidate. On success, we decrement rdcache_revoking,
so that it is no longer equal to rdcache_gen. Similarly, if we success
in doing a sync invalidate, set revoking = gen - 1. (This is a small
optimization to avoid doing unnecessary invalidate work and does not
affect correctness.)
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 0a49ffd..5a9f907 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1394,11 +1394,8 @@
spin_lock(&inode->i_lock);
dout("invalidate_pages %p gen %d revoking %d\n", inode,
ci->i_rdcache_gen, ci->i_rdcache_revoking);
- if (ci->i_rdcache_gen == 0 ||
- ci->i_rdcache_revoking != ci->i_rdcache_gen) {
- BUG_ON(ci->i_rdcache_revoking > ci->i_rdcache_gen);
+ if (ci->i_rdcache_revoking != ci->i_rdcache_gen) {
/* nevermind! */
- ci->i_rdcache_revoking = 0;
spin_unlock(&inode->i_lock);
goto out;
}
@@ -1408,15 +1405,16 @@
ceph_invalidate_nondirty_pages(inode->i_mapping);
spin_lock(&inode->i_lock);
- if (orig_gen == ci->i_rdcache_gen) {
+ if (orig_gen == ci->i_rdcache_gen &&
+ orig_gen == ci->i_rdcache_revoking) {
dout("invalidate_pages %p gen %d successful\n", inode,
ci->i_rdcache_gen);
- ci->i_rdcache_gen = 0;
- ci->i_rdcache_revoking = 0;
+ ci->i_rdcache_revoking--;
check = 1;
} else {
- dout("invalidate_pages %p gen %d raced, gen now %d\n",
- inode, orig_gen, ci->i_rdcache_gen);
+ dout("invalidate_pages %p gen %d raced, now %d revoking %d\n",
+ inode, orig_gen, ci->i_rdcache_gen,
+ ci->i_rdcache_revoking);
}
spin_unlock(&inode->i_lock);