From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Instead of using a linear index to address the pages, use the cookie of
the first entry, since that is what we use to match the page anyway.
This allows us to avoid re-reading the entire cache on a seekdir() type
of operation. The latter is very common when re-exporting NFS, and is a
major performance drain.
The change does affect our duplicate cookie detection, since we can no
longer rely on the page index as a linear offset for detecting whether
we looped backwards. However since we no longer do a linear search
through all the pages on each call to nfs_readdir(), this is less of a
concern than it was previously.
The other downside is that invalidate_mapping_pages() no longer can use
the page index to avoid clearing pages that have been read. A subsequent
patch will restore the functionality this provides to the 'ls -l'
heuristic.
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
fs/nfs/dir.c | 99 +++++++++++++++---------------------------
include/linux/nfs_fs.h | 2 -
2 files changed, 34 insertions(+), 67 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 06bd612296d5..2007eebfb5cf 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -39,6 +39,7 @@
#include <linux/sched.h>
#include <linux/kmemleak.h>
#include <linux/xattr.h>
+#include <linux/xxhash.h>
#include "delegation.h"
#include "iostat.h"
@@ -158,9 +159,7 @@ struct nfs_readdir_descriptor {
pgoff_t page_index_max;
u64 dir_cookie;
u64 last_cookie;
- u64 dup_cookie;
loff_t current_index;
- loff_t prev_index;
__be32 verf[NFS_DIR_VERIFIER_SIZE];
unsigned long dir_verifier;
@@ -170,7 +169,6 @@ struct nfs_readdir_descriptor {
unsigned int cache_entry_index;
unsigned int buffer_fills;
unsigned int dtsize;
- signed char duped;
bool plus;
bool eob;
bool eof;
@@ -333,6 +331,13 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
return ret;
}
+static pgoff_t nfs_readdir_page_cookie_hash(u64 cookie)
+{
+ if (cookie == 0)
+ return 0;
+ return xxhash(&cookie, sizeof(cookie), 0);
+}
+
static bool nfs_readdir_page_cookie_match(struct page *page, u64 last_cookie,
u64 change_attr)
{
@@ -354,8 +359,9 @@ static void nfs_readdir_page_unlock_and_put(struct page *page)
}
static struct page *nfs_readdir_page_get_locked(struct address_space *mapping,
- pgoff_t index, u64 last_cookie)
+ u64 last_cookie)
{
+ pgoff_t index = nfs_readdir_page_cookie_hash(last_cookie);
struct page *page;
u64 change_attr;
@@ -374,11 +380,6 @@ static struct page *nfs_readdir_page_get_locked(struct address_space *mapping,
return page;
}
-static loff_t nfs_readdir_page_offset(struct page *page)
-{
- return (loff_t)page->index * (loff_t)nfs_readdir_array_maxentries();
-}
-
static u64 nfs_readdir_page_last_cookie(struct page *page)
{
struct nfs_cache_array *array;
@@ -411,11 +412,11 @@ static void nfs_readdir_page_set_eof(struct page *page)
}
static struct page *nfs_readdir_page_get_next(struct address_space *mapping,
- pgoff_t index, u64 cookie)
+ u64 cookie)
{
struct page *page;
- page = nfs_readdir_page_get_locked(mapping, index, cookie);
+ page = nfs_readdir_page_get_locked(mapping, cookie);
if (page) {
if (nfs_readdir_page_last_cookie(page) == cookie)
return page;
@@ -443,6 +444,13 @@ bool nfs_readdir_use_cookie(const struct file *filp)
return true;
}
+static void nfs_readdir_rewind_search(struct nfs_readdir_descriptor *desc)
+{
+ desc->current_index = 0;
+ desc->last_cookie = 0;
+ desc->page_index = 0;
+}
+
static int nfs_readdir_search_for_pos(struct nfs_cache_array *array,
struct nfs_readdir_descriptor *desc)
{
@@ -491,32 +499,11 @@ static int nfs_readdir_search_for_cookie(struct nfs_cache_array *array,
for (i = 0; i < array->size; i++) {
if (array->array[i].cookie == desc->dir_cookie) {
- struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));
-
- new_pos = nfs_readdir_page_offset(desc->page) + i;
- if (desc->attr_gencount != nfsi->attr_gencount) {
- desc->duped = 0;
- desc->attr_gencount = nfsi->attr_gencount;
- } else if (new_pos < desc->prev_index) {
- if (desc->duped > 0
- && desc->dup_cookie == desc->dir_cookie) {
- if (printk_ratelimit()) {
- pr_notice("NFS: directory %pD2 contains a readdir loop."
- "Please contact your server vendor. "
- "The file: %s has duplicate cookie %llu\n",
- desc->file, array->array[i].name, desc->dir_cookie);
- }
- status = -ELOOP;
- goto out;
- }
- desc->dup_cookie = desc->dir_cookie;
- desc->duped = -1;
- }
+ new_pos = desc->current_index + i;
if (nfs_readdir_use_cookie(desc->file))
desc->ctx->pos = desc->dir_cookie;
else
desc->ctx->pos = new_pos;
- desc->prev_index = new_pos;
desc->cache_entry_index = i;
return 0;
}
@@ -527,7 +514,6 @@ static int nfs_readdir_search_for_cookie(struct nfs_cache_array *array,
if (desc->dir_cookie == array->last_cookie)
desc->eof = true;
}
-out:
return status;
}
@@ -820,18 +806,16 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
break;
arrays++;
*arrays = page = new;
- desc->page_index_max++;
} else {
new = nfs_readdir_page_get_next(mapping,
- page->index + 1,
entry->prev_cookie);
if (!new)
break;
if (page != *arrays)
nfs_readdir_page_unlock_and_put(page);
page = new;
- desc->page_index_max = new->index;
}
+ desc->page_index_max++;
status = nfs_readdir_add_to_array(entry, page);
} while (!status && !entry->eof);
@@ -954,7 +938,6 @@ static struct page *
nfs_readdir_page_get_cached(struct nfs_readdir_descriptor *desc)
{
return nfs_readdir_page_get_locked(desc->file->f_mapping,
- desc->page_index,
desc->last_cookie);
}
@@ -984,7 +967,7 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
trace_nfs_readdir_cache_fill_done(inode, res);
if (res == -EBADCOOKIE || res == -ENOTSYNC) {
invalidate_inode_pages2(desc->file->f_mapping);
- desc->page_index = 0;
+ nfs_readdir_rewind_search(desc);
trace_nfs_readdir_invalidate_cache_range(
inode, 0, MAX_LFS_FILESIZE);
return -EAGAIN;
@@ -998,12 +981,10 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
memcmp(nfsi->cookieverf, verf, sizeof(nfsi->cookieverf))) {
memcpy(nfsi->cookieverf, verf,
sizeof(nfsi->cookieverf));
- invalidate_inode_pages2_range(desc->file->f_mapping,
- desc->page_index_max + 1,
+ invalidate_inode_pages2_range(desc->file->f_mapping, 1,
-1);
trace_nfs_readdir_invalidate_cache_range(
- inode, desc->page_index_max + 1,
- MAX_LFS_FILESIZE);
+ inode, 1, MAX_LFS_FILESIZE);
}
}
res = nfs_readdir_search_array(desc);
@@ -1019,11 +1000,6 @@ static int readdir_search_pagecache(struct nfs_readdir_descriptor *desc)
int res;
do {
- if (desc->page_index == 0) {
- desc->current_index = 0;
- desc->prev_index = 0;
- desc->last_cookie = 0;
- }
res = find_and_lock_cache_page(desc);
} while (res == -EAGAIN);
return res;
@@ -1058,8 +1034,6 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
desc->ctx->pos = desc->dir_cookie;
else
desc->ctx->pos++;
- if (desc->duped != 0)
- desc->duped = 1;
}
if (array->page_is_eof)
desc->eof = !desc->eob;
@@ -1101,7 +1075,6 @@ static int uncached_readdir(struct nfs_readdir_descriptor *desc)
desc->page_index = 0;
desc->cache_entry_index = 0;
desc->last_cookie = desc->dir_cookie;
- desc->duped = 0;
desc->page_index_max = 0;
trace_nfs_readdir_uncached(desc->file, desc->verf, desc->last_cookie,
@@ -1134,6 +1107,8 @@ static int uncached_readdir(struct nfs_readdir_descriptor *desc)
for (i = 0; i < sz && arrays[i]; i++)
nfs_readdir_page_array_free(arrays[i]);
out:
+ if (!nfs_readdir_use_cookie(desc->file))
+ nfs_readdir_rewind_search(desc);
desc->page_index_max = -1;
kfree(arrays);
dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __func__, status);
@@ -1144,17 +1119,14 @@ static int uncached_readdir(struct nfs_readdir_descriptor *desc)
static void nfs_readdir_handle_cache_misses(struct inode *inode,
struct nfs_readdir_descriptor *desc,
- pgoff_t page_index,
unsigned int cache_misses)
{
if (desc->ctx->pos == 0 ||
cache_misses <= NFS_READDIR_CACHE_MISS_THRESHOLD)
return;
- if (invalidate_mapping_pages(inode->i_mapping, page_index + 1, -1) == 0)
+ if (invalidate_mapping_pages(inode->i_mapping, 0, -1) == 0)
return;
- trace_nfs_readdir_invalidate_cache_range(
- inode, (loff_t)(page_index + 1) << PAGE_SHIFT,
- MAX_LFS_FILESIZE);
+ trace_nfs_readdir_invalidate_cache_range(inode, 0, MAX_LFS_FILESIZE);
}
/* The file offset position represents the dirent entry number. A
@@ -1194,8 +1166,6 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
spin_lock(&file->f_lock);
desc->dir_cookie = dir_ctx->dir_cookie;
- desc->dup_cookie = dir_ctx->dup_cookie;
- desc->duped = dir_ctx->duped;
page_index = dir_ctx->page_index;
desc->page_index = page_index;
desc->last_cookie = dir_ctx->last_cookie;
@@ -1213,7 +1183,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
}
desc->plus = nfs_use_readdirplus(inode, ctx, cache_hits, cache_misses);
- nfs_readdir_handle_cache_misses(inode, desc, page_index, cache_misses);
+ nfs_readdir_handle_cache_misses(inode, desc, cache_misses);
do {
res = readdir_search_pagecache(desc);
@@ -1233,7 +1203,6 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
}
if (res == -ETOOSMALL && desc->plus) {
nfs_zap_caches(inode);
- desc->page_index = 0;
desc->plus = false;
desc->eof = false;
continue;
@@ -1252,9 +1221,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
spin_lock(&file->f_lock);
dir_ctx->dir_cookie = desc->dir_cookie;
- dir_ctx->dup_cookie = desc->dup_cookie;
dir_ctx->last_cookie = desc->last_cookie;
- dir_ctx->duped = desc->duped;
dir_ctx->attr_gencount = desc->attr_gencount;
dir_ctx->page_index = desc->page_index;
dir_ctx->eof = desc->eof;
@@ -1297,13 +1264,15 @@ static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
if (offset != filp->f_pos) {
filp->f_pos = offset;
dir_ctx->page_index = 0;
- if (!nfs_readdir_use_cookie(filp))
+ if (!nfs_readdir_use_cookie(filp)) {
dir_ctx->dir_cookie = 0;
- else
+ dir_ctx->last_cookie = 0;
+ } else {
dir_ctx->dir_cookie = offset;
+ dir_ctx->last_cookie = offset;
+ }
if (offset == 0)
memset(dir_ctx->verf, 0, sizeof(dir_ctx->verf));
- dir_ctx->duped = 0;
dir_ctx->eof = false;
}
spin_unlock(&filp->f_lock);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 20a4cf0acad2..42aad886d3c0 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -106,11 +106,9 @@ struct nfs_open_dir_context {
unsigned long attr_gencount;
__be32 verf[NFS_DIR_VERIFIER_SIZE];
__u64 dir_cookie;
- __u64 dup_cookie;
__u64 last_cookie;
pgoff_t page_index;
unsigned int dtsize;
- signed char duped;
bool eof;
struct rcu_head rcu_head;
};
--
2.35.1
