NFS: Readdir plus in v4
By requsting more attributes during a readdir, we can mimic the readdir plus
operation that was in NFSv3.
To test, I ran the command `ls -lU --color=none` on directories with various
numbers of files. Without readdir plus, I see this:
n files | 100 | 1,000 | 10,000 | 100,000 | 1,000,000
--------+-----------+-----------+-----------+-----------+----------
real | 0m00.153s | 0m00.589s | 0m05.601s | 0m56.691s | 9m59.128s
user | 0m00.007s | 0m00.007s | 0m00.077s | 0m00.703s | 0m06.800s
sys | 0m00.010s | 0m00.070s | 0m00.633s | 0m06.423s | 1m10.005s
access | 3 | 1 | 1 | 4 | 31
getattr | 2 | 1 | 1 | 1 | 1
lookup | 104 | 1,003 | 10,003 | 100,003 | 1,000,003
readdir | 2 | 16 | 158 | 1,575 | 15,749
total | 111 | 1,021 | 10,163 | 101,583 | 1,015,784
With readdir plus enabled, I see this:
n files | 100 | 1,000 | 10,000 | 100,000 | 1,000,000
--------+-----------+-----------+-----------+-----------+----------
real | 0m00.115s | 0m00.206s | 0m01.079s | 0m12.521s | 2m07.528s
user | 0m00.003s | 0m00.003s | 0m00.040s | 0m00.290s | 0m03.296s
sys | 0m00.007s | 0m00.020s | 0m00.120s | 0m01.357s | 0m17.556s
access | 3 | 1 | 1 | 1 | 7
getattr | 2 | 1 | 1 | 1 | 1
lookup | 4 | 3 | 3 | 3 | 3
readdir | 6 | 62 | 630 | 6,300 | 62,993
total | 15 | 67 | 635 | 6,305 | 63,004
Readdir plus disabled has about a 16x increase in the number of rpc calls and
is 4 - 5 times slower on large directories.
Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 0cbb714..2a768d0 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -172,7 +172,7 @@
#define MAX_READDIR_ARRAY ((PAGE_SIZE - sizeof(struct nfs_cache_array)) / sizeof(struct nfs_cache_array_entry))
-typedef __be32 * (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, int);
+typedef __be32 * (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int);
typedef struct {
struct file *file;
struct page *page;
@@ -360,7 +360,7 @@
static
int xdr_decode(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry, struct xdr_stream *stream)
{
- __be32 *p = desc->decode(stream, entry, desc->plus);
+ __be32 *p = desc->decode(stream, entry, NFS_SERVER(desc->file->f_path.dentry->d_inode), desc->plus);
if (IS_ERR(p))
return PTR_ERR(p);