File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
new file mode 100644
index 0000000..d63bea8
--- /dev/null
+++ b/fs/nfs/fscache.c
@@ -0,0 +1,439 @@
+/* NFS filesystem cache interface
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_fs_sb.h>
+#include <linux/in6.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+
+#include "internal.h"
+#include "iostat.h"
+#include "fscache.h"
+
+#define NFSDBG_FACILITY NFSDBG_FSCACHE
+
+static struct rb_root nfs_fscache_keys = RB_ROOT;
+static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
+
+/*
+ * Get the per-client index cookie for an NFS client if the appropriate mount
+ * flag was set
+ * - We always try and get an index cookie for the client, but get filehandle
+ * cookies on a per-superblock basis, depending on the mount flags
+ */
+void nfs_fscache_get_client_cookie(struct nfs_client *clp)
+{
+ /* create a cache index for looking up filehandles */
+ clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
+ &nfs_fscache_server_index_def,
+ clp, true);
+ dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
+ clp, clp->fscache);
+}
+
+/*
+ * Dispose of a per-client cookie
+ */
+void nfs_fscache_release_client_cookie(struct nfs_client *clp)
+{
+ dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
+ clp, clp->fscache);
+
+ fscache_relinquish_cookie(clp->fscache, 0);
+ clp->fscache = NULL;
+}
+
+/*
+ * Get the cache cookie for an NFS superblock. We have to handle
+ * uniquification here because the cache doesn't do it for us.
+ *
+ * The default uniquifier is just an empty string, but it may be overridden
+ * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
+ * superblock across an automount point of some nature.
+ */
+void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
+{
+ struct nfs_fscache_key *key, *xkey;
+ struct nfs_server *nfss = NFS_SB(sb);
+ struct rb_node **p, *parent;
+ int diff;
+
+ if (!uniq) {
+ uniq = "";
+ ulen = 1;
+ }
+
+ key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
+ if (!key)
+ return;
+
+ key->nfs_client = nfss->nfs_client;
+ key->key.super.s_flags = sb->s_flags & NFS_MS_MASK;
+ key->key.nfs_server.flags = nfss->flags;
+ key->key.nfs_server.rsize = nfss->rsize;
+ key->key.nfs_server.wsize = nfss->wsize;
+ key->key.nfs_server.acregmin = nfss->acregmin;
+ key->key.nfs_server.acregmax = nfss->acregmax;
+ key->key.nfs_server.acdirmin = nfss->acdirmin;
+ key->key.nfs_server.acdirmax = nfss->acdirmax;
+ key->key.nfs_server.fsid = nfss->fsid;
+ key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
+
+ key->key.uniq_len = ulen;
+ memcpy(key->key.uniquifier, uniq, ulen);
+
+ spin_lock(&nfs_fscache_keys_lock);
+ p = &nfs_fscache_keys.rb_node;
+ parent = NULL;
+ while (*p) {
+ parent = *p;
+ xkey = rb_entry(parent, struct nfs_fscache_key, node);
+
+ if (key->nfs_client < xkey->nfs_client)
+ goto go_left;
+ if (key->nfs_client > xkey->nfs_client)
+ goto go_right;
+
+ diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
+ if (diff < 0)
+ goto go_left;
+ if (diff > 0)
+ goto go_right;
+
+ if (key->key.uniq_len == 0)
+ goto non_unique;
+ diff = memcmp(key->key.uniquifier,
+ xkey->key.uniquifier,
+ key->key.uniq_len);
+ if (diff < 0)
+ goto go_left;
+ if (diff > 0)
+ goto go_right;
+ goto non_unique;
+
+ go_left:
+ p = &(*p)->rb_left;
+ continue;
+ go_right:
+ p = &(*p)->rb_right;
+ }
+
+ rb_link_node(&key->node, parent, p);
+ rb_insert_color(&key->node, &nfs_fscache_keys);
+ spin_unlock(&nfs_fscache_keys_lock);
+ nfss->fscache_key = key;
+
+ /* create a cache index for looking up filehandles */
+ nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
+ &nfs_fscache_super_index_def,
+ nfss, true);
+ dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
+ nfss, nfss->fscache);
+ return;
+
+non_unique:
+ spin_unlock(&nfs_fscache_keys_lock);
+ kfree(key);
+ nfss->fscache_key = NULL;
+ nfss->fscache = NULL;
+ printk(KERN_WARNING "NFS:"
+ " Cache request denied due to non-unique superblock keys\n");
+}
+
+/*
+ * release a per-superblock cookie
+ */
+void nfs_fscache_release_super_cookie(struct super_block *sb)
+{
+ struct nfs_server *nfss = NFS_SB(sb);
+
+ dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
+ nfss, nfss->fscache);
+
+ fscache_relinquish_cookie(nfss->fscache, 0);
+ nfss->fscache = NULL;
+
+ if (nfss->fscache_key) {
+ spin_lock(&nfs_fscache_keys_lock);
+ rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
+ spin_unlock(&nfs_fscache_keys_lock);
+ kfree(nfss->fscache_key);
+ nfss->fscache_key = NULL;
+ }
+}
+
+/*
+ * Initialise the per-inode cache cookie pointer for an NFS inode.
+ */
+void nfs_fscache_init_inode(struct inode *inode)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+
+ nfsi->fscache = NULL;
+ if (!S_ISREG(inode->i_mode))
+ return;
+ nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
+ &nfs_fscache_inode_object_def,
+ nfsi, false);
+}
+
+/*
+ * Release a per-inode cookie.
+ */
+void nfs_fscache_clear_inode(struct inode *inode)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+ struct fscache_cookie *cookie = nfs_i_fscache(inode);
+
+ dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
+
+ fscache_relinquish_cookie(cookie, false);
+ nfsi->fscache = NULL;
+}
+
+static bool nfs_fscache_can_enable(void *data)
+{
+ struct inode *inode = data;
+
+ return !inode_is_open_for_write(inode);
+}
+
+/*
+ * Enable or disable caching for a file that is being opened as appropriate.
+ * The cookie is allocated when the inode is initialised, but is not enabled at
+ * that time. Enablement is deferred to file-open time to avoid stat() and
+ * access() thrashing the cache.
+ *
+ * For now, with NFS, only regular files that are open read-only will be able
+ * to use the cache.
+ *
+ * We enable the cache for an inode if we open it read-only and it isn't
+ * currently open for writing. We disable the cache if the inode is open
+ * write-only.
+ *
+ * The caller uses the file struct to pin i_writecount on the inode before
+ * calling us when a file is opened for writing, so we can make use of that.
+ *
+ * Note that this may be invoked multiple times in parallel by parallel
+ * nfs_open() functions.
+ */
+void nfs_fscache_open_file(struct inode *inode, struct file *filp)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+ struct fscache_cookie *cookie = nfs_i_fscache(inode);
+
+ if (!fscache_cookie_valid(cookie))
+ return;
+
+ if (inode_is_open_for_write(inode)) {
+ dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
+ clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
+ fscache_disable_cookie(cookie, true);
+ fscache_uncache_all_inode_pages(cookie, inode);
+ } else {
+ dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
+ fscache_enable_cookie(cookie, nfs_fscache_can_enable, inode);
+ if (fscache_cookie_enabled(cookie))
+ set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
+ }
+}
+EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
+
+/*
+ * Release the caching state associated with a page, if the page isn't busy
+ * interacting with the cache.
+ * - Returns true (can release page) or false (page busy).
+ */
+int nfs_fscache_release_page(struct page *page, gfp_t gfp)
+{
+ if (PageFsCache(page)) {
+ struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
+
+ BUG_ON(!cookie);
+ dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
+ cookie, page, NFS_I(page->mapping->host));
+
+ if (!fscache_maybe_release_page(cookie, page, gfp))
+ return 0;
+
+ nfs_inc_fscache_stats(page->mapping->host,
+ NFSIOS_FSCACHE_PAGES_UNCACHED);
+ }
+
+ return 1;
+}
+
+/*
+ * Release the caching state associated with a page if undergoing complete page
+ * invalidation.
+ */
+void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
+{
+ struct fscache_cookie *cookie = nfs_i_fscache(inode);
+
+ BUG_ON(!cookie);
+
+ dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
+ cookie, page, NFS_I(inode));
+
+ fscache_wait_on_page_write(cookie, page);
+
+ BUG_ON(!PageLocked(page));
+ fscache_uncache_page(cookie, page);
+ nfs_inc_fscache_stats(page->mapping->host,
+ NFSIOS_FSCACHE_PAGES_UNCACHED);
+}
+
+/*
+ * Handle completion of a page being read from the cache.
+ * - Called in process (keventd) context.
+ */
+static void nfs_readpage_from_fscache_complete(struct page *page,
+ void *context,
+ int error)
+{
+ dfprintk(FSCACHE,
+ "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
+ page, context, error);
+
+ /* if the read completes with an error, we just unlock the page and let
+ * the VM reissue the readpage */
+ if (!error) {
+ SetPageUptodate(page);
+ unlock_page(page);
+ } else {
+ error = nfs_readpage_async(context, page->mapping->host, page);
+ if (error)
+ unlock_page(page);
+ }
+}
+
+/*
+ * Retrieve a page from fscache
+ */
+int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
+ struct inode *inode, struct page *page)
+{
+ int ret;
+
+ dfprintk(FSCACHE,
+ "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
+ nfs_i_fscache(inode), page, page->index, page->flags, inode);
+
+ ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
+ page,
+ nfs_readpage_from_fscache_complete,
+ ctx,
+ GFP_KERNEL);
+
+ switch (ret) {
+ case 0: /* read BIO submitted (page in fscache) */
+ dfprintk(FSCACHE,
+ "NFS: readpage_from_fscache: BIO submitted\n");
+ nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
+ return ret;
+
+ case -ENOBUFS: /* inode not in cache */
+ case -ENODATA: /* page not in cache */
+ nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
+ dfprintk(FSCACHE,
+ "NFS: readpage_from_fscache %d\n", ret);
+ return 1;
+
+ default:
+ dfprintk(FSCACHE, "NFS: readpage_from_fscache %d\n", ret);
+ nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
+ }
+ return ret;
+}
+
+/*
+ * Retrieve a set of pages from fscache
+ */
+int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
+ struct inode *inode,
+ struct address_space *mapping,
+ struct list_head *pages,
+ unsigned *nr_pages)
+{
+ unsigned npages = *nr_pages;
+ int ret;
+
+ dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
+ nfs_i_fscache(inode), npages, inode);
+
+ ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
+ mapping, pages, nr_pages,
+ nfs_readpage_from_fscache_complete,
+ ctx,
+ mapping_gfp_mask(mapping));
+ if (*nr_pages < npages)
+ nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
+ npages);
+ if (*nr_pages > 0)
+ nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
+ *nr_pages);
+
+ switch (ret) {
+ case 0: /* read submitted to the cache for all pages */
+ BUG_ON(!list_empty(pages));
+ BUG_ON(*nr_pages != 0);
+ dfprintk(FSCACHE,
+ "NFS: nfs_getpages_from_fscache: submitted\n");
+
+ return ret;
+
+ case -ENOBUFS: /* some pages aren't cached and can't be */
+ case -ENODATA: /* some pages aren't cached */
+ dfprintk(FSCACHE,
+ "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
+ return 1;
+
+ default:
+ dfprintk(FSCACHE,
+ "NFS: nfs_getpages_from_fscache: ret %d\n", ret);
+ }
+
+ return ret;
+}
+
+/*
+ * Store a newly fetched page in fscache
+ * - PG_fscache must be set on the page
+ */
+void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
+{
+ int ret;
+
+ dfprintk(FSCACHE,
+ "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
+ nfs_i_fscache(inode), page, page->index, page->flags, sync);
+
+ ret = fscache_write_page(nfs_i_fscache(inode), page, GFP_KERNEL);
+ dfprintk(FSCACHE,
+ "NFS: readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
+ page, page->index, page->flags, ret);
+
+ if (ret != 0) {
+ fscache_uncache_page(nfs_i_fscache(inode), page);
+ nfs_inc_fscache_stats(inode,
+ NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
+ nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
+ } else {
+ nfs_inc_fscache_stats(inode,
+ NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
+ }
+}