1 files changed, 393 insertions, 0 deletions

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
new file mode 100644
index 000000000..b05717fe0
--- /dev/null
+++ b/fs/nfs/fscache.c
@@ -0,0 +1,393 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* NFS filesystem cache interface
+ *
+ * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#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 <linux/iversion.h>
+#include <linux/xarray.h>
+#include <linux/fscache.h>
+#include <linux/netfs.h>
+
+#include "internal.h"
+#include "iostat.h"
+#include "fscache.h"
+#include "nfstrace.h"
+
+#define NFS_MAX_KEY_LEN 1000
+
+static bool nfs_append_int(char *key, int *_len, unsigned long long x)
+{
+	if (*_len > NFS_MAX_KEY_LEN)
+		return false;
+	if (x == 0)
+		key[(*_len)++] = ',';
+	else
+		*_len += sprintf(key + *_len, ",%llx", x);
+	return true;
+}
+
+/*
+ * 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
+ */
+static bool nfs_fscache_get_client_key(struct nfs_client *clp,
+				       char *key, int *_len)
+{
+	const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
+	const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
+
+	*_len += snprintf(key + *_len, NFS_MAX_KEY_LEN - *_len,
+			  ",%u.%u,%x",
+			  clp->rpc_ops->version,
+			  clp->cl_minorversion,
+			  clp->cl_addr.ss_family);
+
+	switch (clp->cl_addr.ss_family) {
+	case AF_INET:
+		if (!nfs_append_int(key, _len, sin->sin_port) ||
+		    !nfs_append_int(key, _len, sin->sin_addr.s_addr))
+			return false;
+		return true;
+
+	case AF_INET6:
+		if (!nfs_append_int(key, _len, sin6->sin6_port) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[0]) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[1]) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[2]) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[3]))
+			return false;
+		return true;
+
+	default:
+		printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
+		       clp->cl_addr.ss_family);
+		return false;
+	}
+}
+
+/*
+ * Get the cache cookie for an NFS superblock.
+ *
+ * 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.
+ */
+int nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
+{
+	struct fscache_volume *vcookie;
+	struct nfs_server *nfss = NFS_SB(sb);
+	unsigned int len = 3;
+	char *key;
+
+	if (uniq) {
+		nfss->fscache_uniq = kmemdup_nul(uniq, ulen, GFP_KERNEL);
+		if (!nfss->fscache_uniq)
+			return -ENOMEM;
+	}
+
+	key = kmalloc(NFS_MAX_KEY_LEN + 24, GFP_KERNEL);
+	if (!key)
+		return -ENOMEM;
+
+	memcpy(key, "nfs", 3);
+	if (!nfs_fscache_get_client_key(nfss->nfs_client, key, &len) ||
+	    !nfs_append_int(key, &len, nfss->fsid.major) ||
+	    !nfs_append_int(key, &len, nfss->fsid.minor) ||
+	    !nfs_append_int(key, &len, sb->s_flags & NFS_SB_MASK) ||
+	    !nfs_append_int(key, &len, nfss->flags) ||
+	    !nfs_append_int(key, &len, nfss->rsize) ||
+	    !nfs_append_int(key, &len, nfss->wsize) ||
+	    !nfs_append_int(key, &len, nfss->acregmin) ||
+	    !nfs_append_int(key, &len, nfss->acregmax) ||
+	    !nfs_append_int(key, &len, nfss->acdirmin) ||
+	    !nfs_append_int(key, &len, nfss->acdirmax) ||
+	    !nfs_append_int(key, &len, nfss->client->cl_auth->au_flavor))
+		goto out;
+
+	if (ulen > 0) {
+		if (ulen > NFS_MAX_KEY_LEN - len)
+			goto out;
+		key[len++] = ',';
+		memcpy(key + len, uniq, ulen);
+		len += ulen;
+	}
+	key[len] = 0;
+
+	/* create a cache index for looking up filehandles */
+	vcookie = fscache_acquire_volume(key,
+					 NULL, /* preferred_cache */
+					 NULL, 0 /* coherency_data */);
+	if (IS_ERR(vcookie)) {
+		if (vcookie != ERR_PTR(-EBUSY)) {
+			kfree(key);
+			return PTR_ERR(vcookie);
+		}
+		pr_err("NFS: Cache volume key already in use (%s)\n", key);
+		vcookie = NULL;
+	}
+	nfss->fscache = vcookie;
+
+out:
+	kfree(key);
+	return 0;
+}
+
+/*
+ * release a per-superblock cookie
+ */
+void nfs_fscache_release_super_cookie(struct super_block *sb)
+{
+	struct nfs_server *nfss = NFS_SB(sb);
+
+	fscache_relinquish_volume(nfss->fscache, NULL, false);
+	nfss->fscache = NULL;
+	kfree(nfss->fscache_uniq);
+}
+
+/*
+ * Initialise the per-inode cache cookie pointer for an NFS inode.
+ */
+void nfs_fscache_init_inode(struct inode *inode)
+{
+	struct nfs_fscache_inode_auxdata auxdata;
+	struct nfs_server *nfss = NFS_SERVER(inode);
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	netfs_inode(inode)->cache = NULL;
+	if (!(nfss->fscache && S_ISREG(inode->i_mode)))
+		return;
+
+	nfs_fscache_update_auxdata(&auxdata, inode);
+
+	netfs_inode(inode)->cache = fscache_acquire_cookie(
+					       nfss->fscache,
+					       0,
+					       nfsi->fh.data, /* index_key */
+					       nfsi->fh.size,
+					       &auxdata,      /* aux_data */
+					       sizeof(auxdata),
+					       i_size_read(inode));
+
+	if (netfs_inode(inode)->cache)
+		mapping_set_release_always(inode->i_mapping);
+}
+
+/*
+ * Release a per-inode cookie.
+ */
+void nfs_fscache_clear_inode(struct inode *inode)
+{
+	fscache_relinquish_cookie(netfs_i_cookie(netfs_inode(inode)), false);
+	netfs_inode(inode)->cache = NULL;
+}
+
+/*
+ * 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_fscache_inode_auxdata auxdata;
+	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
+	bool open_for_write = inode_is_open_for_write(inode);
+
+	if (!fscache_cookie_valid(cookie))
+		return;
+
+	fscache_use_cookie(cookie, open_for_write);
+	if (open_for_write) {
+		nfs_fscache_update_auxdata(&auxdata, inode);
+		fscache_invalidate(cookie, &auxdata, i_size_read(inode),
+				   FSCACHE_INVAL_DIO_WRITE);
+	}
+}
+EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
+
+void nfs_fscache_release_file(struct inode *inode, struct file *filp)
+{
+	struct nfs_fscache_inode_auxdata auxdata;
+	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
+	loff_t i_size = i_size_read(inode);
+
+	nfs_fscache_update_auxdata(&auxdata, inode);
+	fscache_unuse_cookie(cookie, &auxdata, &i_size);
+}
+
+int nfs_netfs_read_folio(struct file *file, struct folio *folio)
+{
+	if (!netfs_inode(folio_inode(folio))->cache)
+		return -ENOBUFS;
+
+	return netfs_read_folio(file, folio);
+}
+
+int nfs_netfs_readahead(struct readahead_control *ractl)
+{
+	struct inode *inode = ractl->mapping->host;
+
+	if (!netfs_inode(inode)->cache)
+		return -ENOBUFS;
+
+	netfs_readahead(ractl);
+	return 0;
+}
+
+static atomic_t nfs_netfs_debug_id;
+static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
+{
+	rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
+	rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
+
+	return 0;
+}
+
+static void nfs_netfs_free_request(struct netfs_io_request *rreq)
+{
+	put_nfs_open_context(rreq->netfs_priv);
+}
+
+static inline int nfs_netfs_begin_cache_operation(struct netfs_io_request *rreq)
+{
+	return fscache_begin_read_operation(&rreq->cache_resources,
+					    netfs_i_cookie(netfs_inode(rreq->inode)));
+}
+
+static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
+{
+	struct nfs_netfs_io_data *netfs;
+
+	netfs = kzalloc(sizeof(*netfs), GFP_KERNEL_ACCOUNT);
+	if (!netfs)
+		return NULL;
+	netfs->sreq = sreq;
+	refcount_set(&netfs->refcount, 1);
+	return netfs;
+}
+
+static bool nfs_netfs_clamp_length(struct netfs_io_subrequest *sreq)
+{
+	size_t	rsize = NFS_SB(sreq->rreq->inode->i_sb)->rsize;
+
+	sreq->len = min(sreq->len, rsize);
+	return true;
+}
+
+static void nfs_netfs_issue_read(struct netfs_io_subrequest *sreq)
+{
+	struct nfs_netfs_io_data	*netfs;
+	struct nfs_pageio_descriptor	pgio;
+	struct inode *inode = sreq->rreq->inode;
+	struct nfs_open_context *ctx = sreq->rreq->netfs_priv;
+	struct page *page;
+	int err;
+	pgoff_t start = (sreq->start + sreq->transferred) >> PAGE_SHIFT;
+	pgoff_t last = ((sreq->start + sreq->len -
+			 sreq->transferred - 1) >> PAGE_SHIFT);
+	XA_STATE(xas, &sreq->rreq->mapping->i_pages, start);
+
+	nfs_pageio_init_read(&pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+
+	netfs = nfs_netfs_alloc(sreq);
+	if (!netfs)
+		return netfs_subreq_terminated(sreq, -ENOMEM, false);
+
+	pgio.pg_netfs = netfs; /* used in completion */
+
+	xas_lock(&xas);
+	xas_for_each(&xas, page, last) {
+		/* nfs_read_add_folio() may schedule() due to pNFS layout and other RPCs  */
+		xas_pause(&xas);
+		xas_unlock(&xas);
+		err = nfs_read_add_folio(&pgio, ctx, page_folio(page));
+		if (err < 0) {
+			netfs->error = err;
+			goto out;
+		}
+		xas_lock(&xas);
+	}
+	xas_unlock(&xas);
+out:
+	nfs_pageio_complete_read(&pgio);
+	nfs_netfs_put(netfs);
+}
+
+void nfs_netfs_initiate_read(struct nfs_pgio_header *hdr)
+{
+	struct nfs_netfs_io_data        *netfs = hdr->netfs;
+
+	if (!netfs)
+		return;
+
+	nfs_netfs_get(netfs);
+}
+
+int nfs_netfs_folio_unlock(struct folio *folio)
+{
+	struct inode *inode = folio_file_mapping(folio)->host;
+
+	/*
+	 * If fscache is enabled, netfs will unlock pages.
+	 */
+	if (netfs_inode(inode)->cache)
+		return 0;
+
+	return 1;
+}
+
+void nfs_netfs_read_completion(struct nfs_pgio_header *hdr)
+{
+	struct nfs_netfs_io_data        *netfs = hdr->netfs;
+	struct netfs_io_subrequest      *sreq;
+
+	if (!netfs)
+		return;
+
+	sreq = netfs->sreq;
+	if (test_bit(NFS_IOHDR_EOF, &hdr->flags))
+		__set_bit(NETFS_SREQ_CLEAR_TAIL, &sreq->flags);
+
+	if (hdr->error)
+		netfs->error = hdr->error;
+	else
+		atomic64_add(hdr->res.count, &netfs->transferred);
+
+	nfs_netfs_put(netfs);
+	hdr->netfs = NULL;
+}
+
+const struct netfs_request_ops nfs_netfs_ops = {
+	.init_request		= nfs_netfs_init_request,
+	.free_request		= nfs_netfs_free_request,
+	.begin_cache_operation	= nfs_netfs_begin_cache_operation,
+	.issue_read		= nfs_netfs_issue_read,
+	.clamp_length		= nfs_netfs_clamp_length
+};