Re: [PATCH 03/12] NFS: Clean up nfs_readdir_page_filler()

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On 2 Nov 2020, at 13:06, trondmy@xxxxxxxxxx wrote:

From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>

Clean up handling of the case where there are no entries in the readdir
reply.

Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
 fs/nfs/dir.c | 39 ++++++++++++++++++---------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 604ebe015387..68acbde3f914 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -601,16 +601,12 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
 	struct xdr_stream stream;
 	struct xdr_buf buf;
 	struct page *scratch;
-	unsigned int count = 0;
 	int status;

 	scratch = alloc_page(GFP_KERNEL);
 	if (scratch == NULL)
 		return -ENOMEM;

-	if (buflen == 0)
-		goto out_nopages;
-
 	xdr_init_decode_pages(&stream, &buf, xdr_pages, buflen);
 	xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);

@@ -619,27 +615,27 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
 			entry->label->len = NFS4_MAXLABELLEN;

 		status = xdr_decode(desc, entry, &stream);
-		if (status != 0) {
-			if (status == -EAGAIN)
-				status = 0;
+		if (status != 0)
 			break;
-		}
-
-		count++;

 		if (desc->plus)
 			nfs_prime_dcache(file_dentry(desc->file), entry,
 					desc->dir_verifier);

 		status = nfs_readdir_add_to_array(entry, page);
-		if (status != 0)
-			break;
-	} while (!entry->eof);
+	} while (!status && !entry->eof);

-out_nopages:
-	if (count == 0 || (status == -EBADCOOKIE && entry->eof != 0)) {
-		nfs_readdir_page_set_eof(page);
+	switch (status) {
+	case -EBADCOOKIE:
+		if (entry->eof) {
+			nfs_readdir_page_set_eof(page);
+			status = 0;
+		}
+		break;
+	case -ENOSPC:

If you return ENOSPC, then you don't need to use
nfs_readdir_array_is_full(array) below..

+	case -EAGAIN:
 		status = 0;
+		break;
 	}

 	put_page(scratch);
@@ -714,14 +710,15 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,

 		if (status < 0)
 			break;
+
 		pglen = status;
-		status = nfs_readdir_page_filler(desc, &entry, pages, page, pglen);
-		if (status < 0) {
-			if (status == -ENOSPC)
-				status = 0;
+		if (pglen == 0) {
+			nfs_readdir_page_set_eof(page);
 			break;
 		}
-	} while (!nfs_readdir_array_is_full(array));
+
+		status = nfs_readdir_page_filler(desc, &entry, pages, page, pglen);
+	} while (!status && !nfs_readdir_array_is_full(array));

^^ here.

I suppose nfs_readdir_array_is_full() is nice and clear.. I wonder if the
compiler would optimize it away.

Ben




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