NFS: Fix up forced readdirplus

Avoid clearing the entire readdir page cache if we're just doing forced
readdirplus for the 'ls -l' heuristic.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 8c2552d..f6aac1e 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -170,6 +170,7 @@ struct nfs_readdir_descriptor {
        unsigned int    cache_entry_index;
        unsigned int    buffer_fills;
        unsigned int    dtsize;
+       bool clear_cache;
        bool plus;
        bool eob;
        bool eof;
@@ -227,6 +228,13 @@ static void nfs_readdir_clear_array(struct page *page)
        kunmap_atomic(array);
 }
 
+static void nfs_readdir_page_reinit_array(struct page *page, u64 last_cookie,
+                                         u64 change_attr)
+{
+       nfs_readdir_clear_array(page);
+       nfs_readdir_page_init_array(page, last_cookie, change_attr);
+}
+
 static struct page *
 nfs_readdir_page_array_alloc(u64 last_cookie, gfp_t gfp_flags)
 {
@@ -428,12 +436,11 @@ static struct page *nfs_readdir_page_get_next(struct address_space *mapping,
        struct page *page;
 
        page = nfs_readdir_page_get_locked(mapping, cookie, change_attr);
-       if (page) {
-               if (nfs_readdir_page_last_cookie(page) == cookie)
-                       return page;
-               nfs_readdir_page_unlock_and_put(page);
-       }
-       return NULL;
+       if (!page)
+               return NULL;
+       if (nfs_readdir_page_last_cookie(page) != cookie)
+               nfs_readdir_page_reinit_array(page, cookie, change_attr);
+       return page;
 }
 
 static inline
@@ -960,9 +967,15 @@ nfs_readdir_page_get_cached(struct nfs_readdir_descriptor *desc)
 {
        struct address_space *mapping = desc->file->f_mapping;
        u64 change_attr = inode_peek_iversion_raw(mapping->host);
+       u64 cookie = desc->last_cookie;
+       struct page *page;
 
-       return nfs_readdir_page_get_locked(mapping, desc->last_cookie,
-                                          change_attr);
+       page = nfs_readdir_page_get_locked(mapping, cookie, change_attr);
+       if (!page)
+               return NULL;
+       if (desc->clear_cache && !nfs_readdir_page_needs_filling(page))
+               nfs_readdir_page_reinit_array(page, cookie, change_attr);
+       return page;
 }
 
 /*
@@ -1013,6 +1026,7 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
                        trace_nfs_readdir_invalidate_cache_range(
                                inode, 1, MAX_LFS_FILESIZE);
                }
+               desc->clear_cache = false;
        }
        res = nfs_readdir_search_array(desc);
        if (res == 0)
@@ -1147,16 +1161,17 @@ out:
 
 #define NFS_READDIR_CACHE_MISS_THRESHOLD (16UL)
 
-static void nfs_readdir_handle_cache_misses(struct inode *inode,
+static bool nfs_readdir_handle_cache_misses(struct inode *inode,
                                            struct nfs_readdir_descriptor *desc,
-                                           unsigned int cache_misses)
+                                           unsigned int cache_misses,
+                                           bool force_clear)
 {
-       if (desc->ctx->pos == 0 ||
-           cache_misses <= NFS_READDIR_CACHE_MISS_THRESHOLD)
-               return;
-       if (invalidate_mapping_pages(inode->i_mapping, 0, -1) == 0)
-               return;
-       trace_nfs_readdir_invalidate_cache_range(inode, 0, MAX_LFS_FILESIZE);
+       if (desc->ctx->pos == 0 || !desc->plus)
+               return false;
+       if (cache_misses <= NFS_READDIR_CACHE_MISS_THRESHOLD && !force_clear)
+               return false;
+       trace_nfs_readdir_force_readdirplus(inode);
+       return true;
 }
 
 /* The file offset position represents the dirent entry number.  A
@@ -1171,6 +1186,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
        struct nfs_open_dir_context *dir_ctx = file->private_data;
        struct nfs_readdir_descriptor *desc;
        unsigned int cache_hits, cache_misses;
+       bool force_clear;
        int res;
 
        dfprintk(FILE, "NFS: readdir(%pD2) starting at cookie %llu\n",
@@ -1203,6 +1219,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
        memcpy(desc->verf, dir_ctx->verf, sizeof(desc->verf));
        cache_hits = atomic_xchg(&dir_ctx->cache_hits, 0);
        cache_misses = atomic_xchg(&dir_ctx->cache_misses, 0);
+       force_clear = dir_ctx->force_clear;
        spin_unlock(&file->f_lock);
 
        if (desc->eof) {
@@ -1211,7 +1228,9 @@ 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, cache_misses);
+       force_clear = nfs_readdir_handle_cache_misses(inode, desc, cache_misses,
+                                                     force_clear);
+       desc->clear_cache = force_clear;
 
        do {
                res = readdir_search_pagecache(desc);
@@ -1240,6 +1259,8 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
 
                nfs_do_filldir(desc, nfsi->cookieverf);
                nfs_readdir_page_unlock_and_put_cached(desc);
+               if (desc->page_index == desc->page_index_max)
+                       desc->clear_cache = force_clear;
        } while (!desc->eob && !desc->eof);
 
        spin_lock(&file->f_lock);
@@ -1247,6 +1268,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
        dir_ctx->last_cookie = desc->last_cookie;
        dir_ctx->attr_gencount = desc->attr_gencount;
        dir_ctx->page_index = desc->page_index;
+       dir_ctx->force_clear = force_clear;
        dir_ctx->eof = desc->eof;
        dir_ctx->dtsize = desc->dtsize;
        memcpy(dir_ctx->verf, desc->verf, sizeof(dir_ctx->verf));

diff --git a/fs/nfs/nfstrace.h b/fs/nfs/nfstrace.h
index ec2645d..59f4ca8 100644 (file)
--- a/fs/nfs/nfstrace.h
+++ b/fs/nfs/nfstrace.h
@@ -160,6 +160,7 @@ DEFINE_NFS_INODE_EVENT(nfs_fsync_enter);
 DEFINE_NFS_INODE_EVENT_DONE(nfs_fsync_exit);
 DEFINE_NFS_INODE_EVENT(nfs_access_enter);
 DEFINE_NFS_INODE_EVENT_DONE(nfs_set_cache_invalid);
+DEFINE_NFS_INODE_EVENT(nfs_readdir_force_readdirplus);
 DEFINE_NFS_INODE_EVENT_DONE(nfs_readdir_cache_fill_done);
 DEFINE_NFS_INODE_EVENT_DONE(nfs_readdir_uncached_done);
 

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 42aad88..3893386 100644 (file)
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -109,6 +109,7 @@ struct nfs_open_dir_context {
        __u64 last_cookie;
        pgoff_t page_index;
        unsigned int dtsize;
+       bool force_clear;
        bool eof;
        struct rcu_head rcu_head;
 };