[PATCH] Optimise NFS readdir hack slightly.

[David Woodhouse <dwmw2@infradead.org>]

Avoid calling the underlying ->readdir() again when we reached the end
already; keep going round the loop only if we stopped due to our own
buffer being full.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index d789fb8..7631bd1 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1832,6 +1832,7 @@ struct buffered_dirent {
 struct readdir_data {
 	char		*dirent;
 	size_t		used;
+	int		full;
 };
 
 static int nfsd_buffered_filldir(void *__buf, const char *name, int namlen,
@@ -1842,8 +1843,10 @@ static int nfsd_buffered_filldir(void *__buf, const char *name, int namlen,
 	unsigned int reclen;
 
 	reclen = ALIGN(sizeof(struct buffered_dirent) + namlen, sizeof(u64));
-	if (buf->used + reclen > PAGE_SIZE)
+	if (buf->used + reclen > PAGE_SIZE) {
+		buf->full = 1;
 		return -EINVAL;
+	}
 
 	de->namlen = namlen;
 	de->offset = offset;
@@ -1871,11 +1874,11 @@ static int nfsd_buffered_readdir(struct file *file, filldir_t func,
 	offset = *offsetp;
 	cdp->err = nfserr_eof; /* will be cleared on successful read */
 
-	while (1) {
+	do {
 		unsigned int reclen;
 
 		buf.used = 0;
-
+		buf.full = 0;
 		host_err = vfs_readdir(file, nfsd_buffered_filldir, &buf);
 		if (host_err)
 			break;
@@ -1903,7 +1906,7 @@ static int nfsd_buffered_readdir(struct file *file, filldir_t func,
 			de = (struct buffered_dirent *)((char *)de + reclen);
 		}
 		offset = vfs_llseek(file, 0, 1);
-	}
+	} while (buf.full);
 
  done:
 	free_page((unsigned long)(buf.dirent));

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation