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authorTrond Myklebust <Trond.Myklebust@netapp.com>2008-10-14 19:16:07 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2008-10-14 19:23:17 -0400
commit4704f0e274829e3af00737d2d9adace2d71a9605 (patch)
tree048404f927dc210f1d7c695cb39e28e4e7d49030 /fs/nfs/inode.c
parent921615f111108258820226a3258a047d9bf1d96a (diff)
downloadlinux-4704f0e274829e3af00737d2d9adace2d71a9605.tar.bz2
NFS: Fix the resolution problem with nfs_inode_attrs_need_update()
It appears that 'jiffies' timestamps do not have high enough resolution for nfs_inode_attrs_need_update(). One problem is that a GETATTR can be launched within < 1 jiffy of the last operation that updated the attribute. Another problem is that RPC calls can take < 1 jiffy to execute. We can fix this by switching the variables to use a simple global counter that gets incremented every time we start another GETATTR call. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs/inode.c')
-rw-r--r--fs/nfs/inode.c37
1 files changed, 30 insertions, 7 deletions
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index de3f11e6234e..116a3bd2bc9b 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -305,7 +305,7 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
init_special_inode(inode, inode->i_mode, fattr->rdev);
nfsi->read_cache_jiffies = fattr->time_start;
- nfsi->last_updated = now;
+ nfsi->attr_gencount = fattr->gencount;
nfsi->cache_change_attribute = now;
inode->i_atime = fattr->atime;
inode->i_mtime = fattr->mtime;
@@ -909,6 +909,30 @@ static int nfs_size_need_update(const struct inode *inode, const struct nfs_fatt
return nfs_size_to_loff_t(fattr->size) > i_size_read(inode);
}
+static unsigned long nfs_attr_generation_counter;
+
+static unsigned long nfs_read_attr_generation_counter(void)
+{
+ smp_rmb();
+ return nfs_attr_generation_counter;
+}
+
+unsigned long nfs_inc_attr_generation_counter(void)
+{
+ unsigned long ret;
+ smp_rmb();
+ ret = ++nfs_attr_generation_counter;
+ smp_wmb();
+ return ret;
+}
+
+void nfs_fattr_init(struct nfs_fattr *fattr)
+{
+ fattr->valid = 0;
+ fattr->time_start = jiffies;
+ fattr->gencount = nfs_inc_attr_generation_counter();
+}
+
/**
* nfs_inode_attrs_need_update - check if the inode attributes need updating
* @inode - pointer to inode
@@ -922,8 +946,7 @@ static int nfs_size_need_update(const struct inode *inode, const struct nfs_fatt
* catch the case where ctime either didn't change, or went backwards
* (if someone reset the clock on the server) by looking at whether
* or not this RPC call was started after the inode was last updated.
- * Note also the check for jiffy wraparound if the last_updated timestamp
- * is later than 'jiffies'.
+ * Note also the check for wraparound of 'attr_gencount'
*
* The function returns 'true' if it thinks the attributes in 'fattr' are
* more recent than the ones cached in the inode.
@@ -933,10 +956,10 @@ static int nfs_inode_attrs_need_update(const struct inode *inode, const struct n
{
const struct nfs_inode *nfsi = NFS_I(inode);
- return time_after(fattr->time_start, nfsi->last_updated) ||
+ return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 ||
nfs_ctime_need_update(inode, fattr) ||
nfs_size_need_update(inode, fattr) ||
- time_after(nfsi->last_updated, jiffies);
+ ((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0);
}
static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
@@ -1107,7 +1130,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
}
/* If ctime has changed we should definitely clear access+acl caches */
if (!timespec_equal(&inode->i_ctime, &fattr->ctime))
- invalid |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
+ invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
} else if (nfsi->change_attr != fattr->change_attr) {
dprintk("NFS: change_attr change on server for file %s/%ld\n",
inode->i_sb->s_id, inode->i_ino);
@@ -1163,7 +1186,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
nfs_inc_stats(inode, NFSIOS_ATTRINVALIDATE);
nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
nfsi->attrtimeo_timestamp = now;
- nfsi->last_updated = now;
+ nfsi->attr_gencount = nfs_inc_attr_generation_counter();
} else {
if (!time_in_range(now, nfsi->attrtimeo_timestamp, nfsi->attrtimeo_timestamp + nfsi->attrtimeo)) {
if ((nfsi->attrtimeo <<= 1) > NFS_MAXATTRTIMEO(inode))