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authorSage Weil <sage@newdream.net>2010-11-04 11:05:05 -0700
committerSage Weil <sage@newdream.net>2010-11-08 07:29:05 -0800
commitcd045cb42a266882ac24bc21a3a8d03683c72954 (patch)
tree2938560e8362804e829cc9feb23ef746d354140b
parentfeb4cc9bb433bf1491ac5ffbba133f3258dacf06 (diff)
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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>
-rw-r--r--fs/ceph/caps.c4
-rw-r--r--fs/ceph/inode.c16
-rw-r--r--fs/ceph/super.h4
3 files changed, 10 insertions, 14 deletions
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 04b207b0c84..60d27bc9eb8 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1430,8 +1430,8 @@ static int try_nonblocking_invalidate(struct inode *inode)
invalidating_gen == ci->i_rdcache_gen) {
/* success. */
dout("try_nonblocking_invalidate %p success\n", inode);
- ci->i_rdcache_gen = 0;
- ci->i_rdcache_revoking = 0;
+ /* save any racing async invalidate some trouble */
+ ci->i_rdcache_revoking = ci->i_rdcache_gen - 1;
return 0;
}
dout("try_nonblocking_invalidate %p failed\n", inode);
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 0a49ffde5bc..5a9f907b805 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1394,11 +1394,8 @@ static void ceph_invalidate_work(struct work_struct *work)
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 @@ static void ceph_invalidate_work(struct work_struct *work)
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);
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 1886294e12f..7f01728a465 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -293,9 +293,7 @@ struct ceph_inode_info {
int i_rd_ref, i_rdcache_ref, i_wr_ref;
int i_wrbuffer_ref, i_wrbuffer_ref_head;
u32 i_shared_gen; /* increment each time we get FILE_SHARED */
- u32 i_rdcache_gen; /* we increment this each time we get
- FILE_CACHE. If it's non-zero, we
- _may_ have cached pages. */
+ u32 i_rdcache_gen; /* incremented each time we get FILE_CACHE. */
u32 i_rdcache_revoking; /* RDCACHE gen to async invalidate, if any */
struct list_head i_unsafe_writes; /* uncommitted sync writes */