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authorPeter Staubach <staubach@redhat.com>2008-12-23 15:21:56 -0500
committerTrond Myklebust <Trond.Myklebust@netapp.com>2008-12-23 15:21:56 -0500
commit64672d55d93c26fb4035fd1a84a803cbc09cb058 (patch)
tree6873f9335b925e4c6a5336544a6f6fc1d789604f /fs/nfs
parentdc0b027dfadfcb8a5504f7d8052754bf8d501ab9 (diff)
downloadlinux-64672d55d93c26fb4035fd1a84a803cbc09cb058.tar.bz2
optimize attribute timeouts for "noac" and "actimeo=0"
Hi. I've been looking at a bugzilla which describes a problem where a customer was advised to use either the "noac" or "actimeo=0" mount options to solve a consistency problem that they were seeing in the file attributes. It turned out that this solution did not work reliably for them because sometimes, the local attribute cache was believed to be valid and not timed out. (With an attribute cache timeout of 0, the cache should always appear to be timed out.) In looking at this situation, it appears to me that the problem is that the attribute cache timeout code has an off-by-one error in it. It is assuming that the cache is valid in the region, [read_cache_jiffies, read_cache_jiffies + attrtimeo]. The cache should be considered valid only in the region, [read_cache_jiffies, read_cache_jiffies + attrtimeo). With this change, the options, "noac" and "actimeo=0", work as originally expected. This problem was previously addressed by special casing the attrtimeo == 0 case. However, since the problem is only an off- by-one error, the cleaner solution is address the off-by-one error and thus, not require the special case. Thanx... ps Signed-off-by: Peter Staubach <staubach@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/dir.c2
-rw-r--r--fs/nfs/inode.c11
2 files changed, 3 insertions, 10 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ed7024c34885..e35c8199f82f 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1798,7 +1798,7 @@ static int nfs_access_get_cached(struct inode *inode, struct rpc_cred *cred, str
if (cache == NULL)
goto out;
if (!nfs_have_delegation(inode, FMODE_READ) &&
- !time_in_range(jiffies, cache->jiffies, cache->jiffies + nfsi->attrtimeo))
+ !time_in_range_open(jiffies, cache->jiffies, cache->jiffies + nfsi->attrtimeo))
goto out_stale;
res->jiffies = cache->jiffies;
res->cred = cache->cred;
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 1cf39202c3ea..0c381686171e 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -712,14 +712,7 @@ int nfs_attribute_timeout(struct inode *inode)
if (nfs_have_delegation(inode, FMODE_READ))
return 0;
- /*
- * Special case: if the attribute timeout is set to 0, then always
- * treat the cache as having expired (unless holding
- * a delegation).
- */
- if (nfsi->attrtimeo == 0)
- return 1;
- return !time_in_range(jiffies, nfsi->read_cache_jiffies, nfsi->read_cache_jiffies + nfsi->attrtimeo);
+ return !time_in_range_open(jiffies, nfsi->read_cache_jiffies, nfsi->read_cache_jiffies + nfsi->attrtimeo);
}
/**
@@ -1182,7 +1175,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
nfsi->attrtimeo_timestamp = now;
nfsi->attr_gencount = nfs_inc_attr_generation_counter();
} else {
- if (!time_in_range(now, nfsi->attrtimeo_timestamp, nfsi->attrtimeo_timestamp + nfsi->attrtimeo)) {
+ if (!time_in_range_open(now, nfsi->attrtimeo_timestamp, nfsi->attrtimeo_timestamp + nfsi->attrtimeo)) {
if ((nfsi->attrtimeo <<= 1) > NFS_MAXATTRTIMEO(inode))
nfsi->attrtimeo = NFS_MAXATTRTIMEO(inode);
nfsi->attrtimeo_timestamp = now;