When a directory contains 17 files (except . and ..), nfs client sends
a redundant readdir request after get eof.
A simple reproduce,
At NFS server, create a directory with 17 files under exported directory.
# mkdir test
# cd test
# for i in {0..16} ; do touch $i; done
At NFS client, no matter mounting through nfsv3 or nfsv4,
does ls (or ll) at the created test directory.
A tshark output likes following (for nfsv4),
# tshark -i eth0 tcp port 2049 -Tfields -e ip.src -e ip.dst -e nfs -e nfs.cookie4
srcip dstip SEQUENCE, PUTFH, READDIR 0
dstip srcip SEQUENCE PUTFH READDIR 909539109313539306,2108391201987888856,2305312124304486544,2566335452463141496,2978225129081509984,4263037479923412583,4304697173036510679,4666703455469210097,4759208201298769007,4776701232145978803,5338408478512081262,5949498658935544804,5971526429894832903,6294060338267709855,6528840566229532529,8600463293536422524,9223372036854775807
srcip dstip
srcip dstip SEQUENCE, PUTFH, READDIR 9223372036854775807
dstip srcip SEQUENCE PUTFH READDIR
The READDIR with cookie 9223372036854775807(0x7FFFFFFFFFFFFFFF) is redundant.
Reviewed-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
Signed-off-by: Kinglong Mee <kinglongmee@xxxxxxxxx>
---
fs/nfs/dir.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 8f3112e71a6a..e6a51fd94fea 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1089,6 +1089,17 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
for (i = desc->cache_entry_index; i < array->size; i++) {
struct nfs_cache_array_entry *ent;
+ /*
+ * nfs_readdir_handle_cache_misses return force clear at
+ * (cache_misses > NFS_READDIR_CACHE_MISS_THRESHOLD) for
+ * readdir heuristic, NFS_READDIR_CACHE_MISS_THRESHOLD + 1
+ * entries need be emitted here.
+ */
+ if (first_emit && i > NFS_READDIR_CACHE_MISS_THRESHOLD + 2) {
+ desc->eob = true;
+ break;
+ }
+
ent = &array->array[i];
if (!dir_emit(desc->ctx, ent->name, ent->name_len,
nfs_compat_user_ino64(ent->ino), ent->d_type)) {
@@ -1107,10 +1118,6 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
desc->ctx->pos = desc->dir_cookie;
else
desc->ctx->pos++;
- if (first_emit && i > NFS_READDIR_CACHE_MISS_THRESHOLD + 1) {
- desc->eob = true;
- break;
- }
}
if (array->folio_is_eof)
desc->eof = !desc->eob;
--
2.41.0
