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>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 49d5654..4807074 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -156,6 +156,7 @@
decode_dirent_t decode;
int plus;
unsigned long timestamp;
+ unsigned long gencount;
int timestamp_valid;
} nfs_readdir_descriptor_t;
@@ -177,7 +178,7 @@
struct file *file = desc->file;
struct inode *inode = file->f_path.dentry->d_inode;
struct rpc_cred *cred = nfs_file_cred(file);
- unsigned long timestamp;
+ unsigned long timestamp, gencount;
int error;
dfprintk(DIRCACHE, "NFS: %s: reading cookie %Lu into page %lu\n",
@@ -186,6 +187,7 @@
again:
timestamp = jiffies;
+ gencount = nfs_inc_attr_generation_counter();
error = NFS_PROTO(inode)->readdir(file->f_path.dentry, cred, desc->entry->cookie, page,
NFS_SERVER(inode)->dtsize, desc->plus);
if (error < 0) {
@@ -199,6 +201,7 @@
goto error;
}
desc->timestamp = timestamp;
+ desc->gencount = gencount;
desc->timestamp_valid = 1;
SetPageUptodate(page);
/* Ensure consistent page alignment of the data.
@@ -224,9 +227,10 @@
if (IS_ERR(p))
return PTR_ERR(p);
desc->ptr = p;
- if (desc->timestamp_valid)
+ if (desc->timestamp_valid) {
desc->entry->fattr->time_start = desc->timestamp;
- else
+ desc->entry->fattr->gencount = desc->gencount;
+ } else
desc->entry->fattr->valid &= ~NFS_ATTR_FATTR;
return 0;
}
@@ -471,7 +475,7 @@
struct rpc_cred *cred = nfs_file_cred(file);
struct page *page = NULL;
int status;
- unsigned long timestamp;
+ unsigned long timestamp, gencount;
dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
(unsigned long long)*desc->dir_cookie);
@@ -482,6 +486,7 @@
goto out;
}
timestamp = jiffies;
+ gencount = nfs_inc_attr_generation_counter();
status = NFS_PROTO(inode)->readdir(file->f_path.dentry, cred,
*desc->dir_cookie, page,
NFS_SERVER(inode)->dtsize,
@@ -490,6 +495,7 @@
desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */
if (status >= 0) {
desc->timestamp = timestamp;
+ desc->gencount = gencount;
desc->timestamp_valid = 1;
if ((status = dir_decode(desc)) == 0)
desc->entry->prev_cookie = *desc->dir_cookie;