Re: [PATCH v5 00/22] Readdir enhancements

[Trond Myklebust <trondmy@hammerspace.com>]

On Thu, 2020-11-12 at 16:51 +0000, Trond Myklebust wrote:
> 
> I was going to ask you if perhaps reverting Scott's commit
> 07b5ce8ef2d8
> ("NFS: Make nfs_readdir revalidate less often") might help here?
> My thinking is that will trigger more cache invalidations when the
> directory is changing underneath us, and will now trigger uncached
> readdir in those situations.
> 
> > 

IOW, the suggestion would be to apply something like the following on
top of the existing readdir patchset:

---
 fs/nfs/dir.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 3f70697729d8..384a4663f742 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -956,10 +956,10 @@ static int readdir_search_pagecache(struct
nfs_readdir_descriptor *desc)
 {
 	int res;
 
-	if (nfs_readdir_dont_search_cache(desc))
-		return -EBADCOOKIE;
-
 	do {
+		if (nfs_readdir_dont_search_cache(desc))
+			return -EBADCOOKIE;
+
 		if (desc->page_index == 0) {
 			desc->current_index = 0;
 			desc->prev_index = 0;
@@ -1082,11 +1082,9 @@ static int nfs_readdir(struct file *file, struct
dir_context *ctx)
 	 * to either find the entry with the appropriate number or
 	 * revalidate the cookie.
 	 */
-	if (ctx->pos == 0 || nfs_attribute_cache_expired(inode)) {
-		res = nfs_revalidate_mapping(inode, file->f_mapping);
-		if (res < 0)
-			goto out;
-	}
+	res = nfs_revalidate_mapping(inode, file->f_mapping);
+	if (res < 0)
+		goto out;
 
 	res = -ENOMEM;
 	desc = kzalloc(sizeof(*desc), GFP_KERNEL);


-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com