Initial import

1 files changed, 947 insertions, 0 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
new file mode 100644
index 000000000..8b8d83a52
--- /dev/null
+++ b/fs/nfs/file.c
@@ -0,0 +1,947 @@
+/*
+ *  linux/fs/nfs/file.c
+ *
+ *  Copyright (C) 1992  Rick Sladkey
+ *
+ *  Changes Copyright (C) 1994 by Florian La Roche
+ *   - Do not copy data too often around in the kernel.
+ *   - In nfs_file_read the return value of kmalloc wasn't checked.
+ *   - Put in a better version of read look-ahead buffering. Original idea
+ *     and implementation by Wai S Kok elekokws@ee.nus.sg.
+ *
+ *  Expire cache on write to a file by Wai S Kok (Oct 1994).
+ *
+ *  Total rewrite of read side for new NFS buffer cache.. Linus.
+ *
+ *  nfs regular file handling functions
+ */
+
+#include <linux/module.h>
+#include <linux/time.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/stat.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_mount.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/gfp.h>
+#include <linux/swap.h>
+
+#include <asm/uaccess.h>
+
+#include "delegation.h"
+#include "internal.h"
+#include "iostat.h"
+#include "fscache.h"
+#include "pnfs.h"
+
+#include "nfstrace.h"
+
+#define NFSDBG_FACILITY		NFSDBG_FILE
+
+static const struct vm_operations_struct nfs_file_vm_ops;
+
+/* Hack for future NFS swap support */
+#ifndef IS_SWAPFILE
+# define IS_SWAPFILE(inode)	(0)
+#endif
+
+int nfs_check_flags(int flags)
+{
+	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nfs_check_flags);
+
+/*
+ * Open file
+ */
+static int
+nfs_file_open(struct inode *inode, struct file *filp)
+{
+	int res;
+
+	dprintk("NFS: open file(%pD2)\n", filp);
+
+	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
+	res = nfs_check_flags(filp->f_flags);
+	if (res)
+		return res;
+
+	res = nfs_open(inode, filp);
+	return res;
+}
+
+int
+nfs_file_release(struct inode *inode, struct file *filp)
+{
+	dprintk("NFS: release(%pD2)\n", filp);
+
+	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
+	return nfs_release(inode, filp);
+}
+EXPORT_SYMBOL_GPL(nfs_file_release);
+
+/**
+ * nfs_revalidate_size - Revalidate the file size
+ * @inode - pointer to inode struct
+ * @file - pointer to struct file
+ *
+ * Revalidates the file length. This is basically a wrapper around
+ * nfs_revalidate_inode() that takes into account the fact that we may
+ * have cached writes (in which case we don't care about the server's
+ * idea of what the file length is), or O_DIRECT (in which case we
+ * shouldn't trust the cache).
+ */
+static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	if (nfs_have_delegated_attributes(inode))
+		goto out_noreval;
+
+	if (filp->f_flags & O_DIRECT)
+		goto force_reval;
+	if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
+		goto force_reval;
+	if (nfs_attribute_timeout(inode))
+		goto force_reval;
+out_noreval:
+	return 0;
+force_reval:
+	return __nfs_revalidate_inode(server, inode);
+}
+
+loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
+{
+	dprintk("NFS: llseek file(%pD2, %lld, %d)\n",
+			filp, offset, whence);
+
+	/*
+	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
+	 * the cached file length
+	 */
+	if (whence != SEEK_SET && whence != SEEK_CUR) {
+		struct inode *inode = filp->f_mapping->host;
+
+		int retval = nfs_revalidate_file_size(inode, filp);
+		if (retval < 0)
+			return (loff_t)retval;
+	}
+
+	return generic_file_llseek(filp, offset, whence);
+}
+EXPORT_SYMBOL_GPL(nfs_file_llseek);
+
+/*
+ * Flush all dirty pages, and check for write errors.
+ */
+int
+nfs_file_flush(struct file *file, fl_owner_t id)
+{
+	struct inode	*inode = file_inode(file);
+
+	dprintk("NFS: flush(%pD2)\n", file);
+
+	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
+	if ((file->f_mode & FMODE_WRITE) == 0)
+		return 0;
+
+	/*
+	 * If we're holding a write delegation, then just start the i/o
+	 * but don't wait for completion (or send a commit).
+	 */
+	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
+		return filemap_fdatawrite(file->f_mapping);
+
+	/* Flush writes to the server and return any errors */
+	return vfs_fsync(file, 0);
+}
+EXPORT_SYMBOL_GPL(nfs_file_flush);
+
+ssize_t
+nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct inode *inode = file_inode(iocb->ki_filp);
+	ssize_t result;
+
+	if (iocb->ki_flags & IOCB_DIRECT)
+		return nfs_file_direct_read(iocb, to, iocb->ki_pos);
+
+	dprintk("NFS: read(%pD2, %zu@%lu)\n",
+		iocb->ki_filp,
+		iov_iter_count(to), (unsigned long) iocb->ki_pos);
+
+	result = nfs_revalidate_mapping_protected(inode, iocb->ki_filp->f_mapping);
+	if (!result) {
+		result = generic_file_read_iter(iocb, to);
+		if (result > 0)
+			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
+	}
+	return result;
+}
+EXPORT_SYMBOL_GPL(nfs_file_read);
+
+ssize_t
+nfs_file_splice_read(struct file *filp, loff_t *ppos,
+		     struct pipe_inode_info *pipe, size_t count,
+		     unsigned int flags)
+{
+	struct inode *inode = file_inode(filp);
+	ssize_t res;
+
+	dprintk("NFS: splice_read(%pD2, %lu@%Lu)\n",
+		filp, (unsigned long) count, (unsigned long long) *ppos);
+
+	res = nfs_revalidate_mapping_protected(inode, filp->f_mapping);
+	if (!res) {
+		res = generic_file_splice_read(filp, ppos, pipe, count, flags);
+		if (res > 0)
+			nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, res);
+	}
+	return res;
+}
+EXPORT_SYMBOL_GPL(nfs_file_splice_read);
+
+int
+nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
+{
+	struct inode *inode = file_inode(file);
+	int	status;
+
+	dprintk("NFS: mmap(%pD2)\n", file);
+
+	/* Note: generic_file_mmap() returns ENOSYS on nommu systems
+	 *       so we call that before revalidating the mapping
+	 */
+	status = generic_file_mmap(file, vma);
+	if (!status) {
+		vma->vm_ops = &nfs_file_vm_ops;
+		status = nfs_revalidate_mapping(inode, file->f_mapping);
+	}
+	return status;
+}
+EXPORT_SYMBOL_GPL(nfs_file_mmap);
+
+/*
+ * Flush any dirty pages for this process, and check for write errors.
+ * The return status from this call provides a reliable indication of
+ * whether any write errors occurred for this process.
+ *
+ * Notice that it clears the NFS_CONTEXT_ERROR_WRITE before synching to
+ * disk, but it retrieves and clears ctx->error after synching, despite
+ * the two being set at the same time in nfs_context_set_write_error().
+ * This is because the former is used to notify the _next_ call to
+ * nfs_file_write() that a write error occurred, and hence cause it to
+ * fall back to doing a synchronous write.
+ */
+int
+nfs_file_fsync_commit(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct nfs_open_context *ctx = nfs_file_open_context(file);
+	struct inode *inode = file_inode(file);
+	int have_error, do_resend, status;
+	int ret = 0;
+
+	dprintk("NFS: fsync file(%pD2) datasync %d\n", file, datasync);
+
+	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
+	do_resend = test_and_clear_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
+	have_error = test_and_clear_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
+	status = nfs_commit_inode(inode, FLUSH_SYNC);
+	have_error |= test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
+	if (have_error) {
+		ret = xchg(&ctx->error, 0);
+		if (ret)
+			goto out;
+	}
+	if (status < 0) {
+		ret = status;
+		goto out;
+	}
+	do_resend |= test_bit(NFS_CONTEXT_RESEND_WRITES, &ctx->flags);
+	if (do_resend)
+		ret = -EAGAIN;
+out:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nfs_file_fsync_commit);
+
+static int
+nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	int ret;
+	struct inode *inode = file_inode(file);
+
+	trace_nfs_fsync_enter(inode);
+
+	nfs_inode_dio_wait(inode);
+	do {
+		ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
+		if (ret != 0)
+			break;
+		mutex_lock(&inode->i_mutex);
+		ret = nfs_file_fsync_commit(file, start, end, datasync);
+		mutex_unlock(&inode->i_mutex);
+		/*
+		 * If nfs_file_fsync_commit detected a server reboot, then
+		 * resend all dirty pages that might have been covered by
+		 * the NFS_CONTEXT_RESEND_WRITES flag
+		 */
+		start = 0;
+		end = LLONG_MAX;
+	} while (ret == -EAGAIN);
+
+	trace_nfs_fsync_exit(inode, ret);
+	return ret;
+}
+
+/*
+ * Decide whether a read/modify/write cycle may be more efficient
+ * then a modify/write/read cycle when writing to a page in the
+ * page cache.
+ *
+ * The modify/write/read cycle may occur if a page is read before
+ * being completely filled by the writer.  In this situation, the
+ * page must be completely written to stable storage on the server
+ * before it can be refilled by reading in the page from the server.
+ * This can lead to expensive, small, FILE_SYNC mode writes being
+ * done.
+ *
+ * It may be more efficient to read the page first if the file is
+ * open for reading in addition to writing, the page is not marked
+ * as Uptodate, it is not dirty or waiting to be committed,
+ * indicating that it was previously allocated and then modified,
+ * that there were valid bytes of data in that range of the file,
+ * and that the new data won't completely replace the old data in
+ * that range of the file.
+ */
+static int nfs_want_read_modify_write(struct file *file, struct page *page,
+			loff_t pos, unsigned len)
+{
+	unsigned int pglen = nfs_page_length(page);
+	unsigned int offset = pos & (PAGE_CACHE_SIZE - 1);
+	unsigned int end = offset + len;
+
+	if (pnfs_ld_read_whole_page(file->f_mapping->host)) {
+		if (!PageUptodate(page))
+			return 1;
+		return 0;
+	}
+
+	if ((file->f_mode & FMODE_READ) &&	/* open for read? */
+	    !PageUptodate(page) &&		/* Uptodate? */
+	    !PagePrivate(page) &&		/* i/o request already? */
+	    pglen &&				/* valid bytes of file? */
+	    (end < pglen || offset))		/* replace all valid bytes? */
+		return 1;
+	return 0;
+}
+
+/*
+ * This does the "real" work of the write. We must allocate and lock the
+ * page to be sent back to the generic routine, which then copies the
+ * data from user space.
+ *
+ * If the writer ends up delaying the write, the writer needs to
+ * increment the page use counts until he is done with the page.
+ */
+static int nfs_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	int ret;
+	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+	struct page *page;
+	int once_thru = 0;
+
+	dfprintk(PAGECACHE, "NFS: write_begin(%pD2(%lu), %u@%lld)\n",
+		file, mapping->host->i_ino, len, (long long) pos);
+
+start:
+	/*
+	 * Prevent starvation issues if someone is doing a consistency
+	 * sync-to-disk
+	 */
+	ret = wait_on_bit_action(&NFS_I(mapping->host)->flags, NFS_INO_FLUSHING,
+				 nfs_wait_bit_killable, TASK_KILLABLE);
+	if (ret)
+		return ret;
+	/*
+	 * Wait for O_DIRECT to complete
+	 */
+	nfs_inode_dio_wait(mapping->host);
+
+	page = grab_cache_page_write_begin(mapping, index, flags);
+	if (!page)
+		return -ENOMEM;
+	*pagep = page;
+
+	ret = nfs_flush_incompatible(file, page);
+	if (ret) {
+		unlock_page(page);
+		page_cache_release(page);
+	} else if (!once_thru &&
+		   nfs_want_read_modify_write(file, page, pos, len)) {
+		once_thru = 1;
+		ret = nfs_readpage(file, page);
+		page_cache_release(page);
+		if (!ret)
+			goto start;
+	}
+	return ret;
+}
+
+static int nfs_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
+	struct nfs_open_context *ctx = nfs_file_open_context(file);
+	int status;
+
+	dfprintk(PAGECACHE, "NFS: write_end(%pD2(%lu), %u@%lld)\n",
+		file, mapping->host->i_ino, len, (long long) pos);
+
+	/*
+	 * Zero any uninitialised parts of the page, and then mark the page
+	 * as up to date if it turns out that we're extending the file.
+	 */
+	if (!PageUptodate(page)) {
+		unsigned pglen = nfs_page_length(page);
+		unsigned end = offset + len;
+
+		if (pglen == 0) {
+			zero_user_segments(page, 0, offset,
+					end, PAGE_CACHE_SIZE);
+			SetPageUptodate(page);
+		} else if (end >= pglen) {
+			zero_user_segment(page, end, PAGE_CACHE_SIZE);
+			if (offset == 0)
+				SetPageUptodate(page);
+		} else
+			zero_user_segment(page, pglen, PAGE_CACHE_SIZE);
+	}
+
+	status = nfs_updatepage(file, page, offset, copied);
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	if (status < 0)
+		return status;
+	NFS_I(mapping->host)->write_io += copied;
+
+	if (nfs_ctx_key_to_expire(ctx)) {
+		status = nfs_wb_all(mapping->host);
+		if (status < 0)
+			return status;
+	}
+
+	return copied;
+}
+
+/*
+ * Partially or wholly invalidate a page
+ * - Release the private state associated with a page if undergoing complete
+ *   page invalidation
+ * - Called if either PG_private or PG_fscache is set on the page
+ * - Caller holds page lock
+ */
+static void nfs_invalidate_page(struct page *page, unsigned int offset,
+				unsigned int length)
+{
+	dfprintk(PAGECACHE, "NFS: invalidate_page(%p, %u, %u)\n",
+		 page, offset, length);
+
+	if (offset != 0 || length < PAGE_CACHE_SIZE)
+		return;
+	/* Cancel any unstarted writes on this page */
+	nfs_wb_page_cancel(page_file_mapping(page)->host, page);
+
+	nfs_fscache_invalidate_page(page, page->mapping->host);
+}
+
+/*
+ * Attempt to release the private state associated with a page
+ * - Called if either PG_private or PG_fscache is set on the page
+ * - Caller holds page lock
+ * - Return true (may release page) or false (may not)
+ */
+static int nfs_release_page(struct page *page, gfp_t gfp)
+{
+	struct address_space *mapping = page->mapping;
+
+	dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
+
+	/* Always try to initiate a 'commit' if relevant, but only
+	 * wait for it if __GFP_WAIT is set.  Even then, only wait 1
+	 * second and only if the 'bdi' is not congested.
+	 * Waiting indefinitely can cause deadlocks when the NFS
+	 * server is on this machine, when a new TCP connection is
+	 * needed and in other rare cases.  There is no particular
+	 * need to wait extensively here.  A short wait has the
+	 * benefit that someone else can worry about the freezer.
+	 */
+	if (mapping) {
+		struct nfs_server *nfss = NFS_SERVER(mapping->host);
+		nfs_commit_inode(mapping->host, 0);
+		if ((gfp & __GFP_WAIT) &&
+		    !bdi_write_congested(&nfss->backing_dev_info)) {
+			wait_on_page_bit_killable_timeout(page, PG_private,
+							  HZ);
+			if (PagePrivate(page))
+				set_bdi_congested(&nfss->backing_dev_info,
+						  BLK_RW_ASYNC);
+		}
+	}
+	/* If PagePrivate() is set, then the page is not freeable */
+	if (PagePrivate(page))
+		return 0;
+	return nfs_fscache_release_page(page, gfp);
+}
+
+static void nfs_check_dirty_writeback(struct page *page,
+				bool *dirty, bool *writeback)
+{
+	struct nfs_inode *nfsi;
+	struct address_space *mapping = page_file_mapping(page);
+
+	if (!mapping || PageSwapCache(page))
+		return;
+
+	/*
+	 * Check if an unstable page is currently being committed and
+	 * if so, have the VM treat it as if the page is under writeback
+	 * so it will not block due to pages that will shortly be freeable.
+	 */
+	nfsi = NFS_I(mapping->host);
+	if (test_bit(NFS_INO_COMMIT, &nfsi->flags)) {
+		*writeback = true;
+		return;
+	}
+
+	/*
+	 * If PagePrivate() is set, then the page is not freeable and as the
+	 * inode is not being committed, it's not going to be cleaned in the
+	 * near future so treat it as dirty
+	 */
+	if (PagePrivate(page))
+		*dirty = true;
+}
+
+/*
+ * Attempt to clear the private state associated with a page when an error
+ * occurs that requires the cached contents of an inode to be written back or
+ * destroyed
+ * - Called if either PG_private or fscache is set on the page
+ * - Caller holds page lock
+ * - Return 0 if successful, -error otherwise
+ */
+static int nfs_launder_page(struct page *page)
+{
+	struct inode *inode = page_file_mapping(page)->host;
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
+		inode->i_ino, (long long)page_offset(page));
+
+	nfs_fscache_wait_on_page_write(nfsi, page);
+	return nfs_wb_page(inode, page);
+}
+
+#ifdef CONFIG_NFS_SWAP
+static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
+						sector_t *span)
+{
+	int ret;
+	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
+
+	*span = sis->pages;
+
+	rcu_read_lock();
+	ret = xs_swapper(rcu_dereference(clnt->cl_xprt), 1);
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static void nfs_swap_deactivate(struct file *file)
+{
+	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
+
+	rcu_read_lock();
+	xs_swapper(rcu_dereference(clnt->cl_xprt), 0);
+	rcu_read_unlock();
+}
+#endif
+
+const struct address_space_operations nfs_file_aops = {
+	.readpage = nfs_readpage,
+	.readpages = nfs_readpages,
+	.set_page_dirty = __set_page_dirty_nobuffers,
+	.writepage = nfs_writepage,
+	.writepages = nfs_writepages,
+	.write_begin = nfs_write_begin,
+	.write_end = nfs_write_end,
+	.invalidatepage = nfs_invalidate_page,
+	.releasepage = nfs_release_page,
+	.direct_IO = nfs_direct_IO,
+	.migratepage = nfs_migrate_page,
+	.launder_page = nfs_launder_page,
+	.is_dirty_writeback = nfs_check_dirty_writeback,
+	.error_remove_page = generic_error_remove_page,
+#ifdef CONFIG_NFS_SWAP
+	.swap_activate = nfs_swap_activate,
+	.swap_deactivate = nfs_swap_deactivate,
+#endif
+};
+
+/*
+ * Notification that a PTE pointing to an NFS page is about to be made
+ * writable, implying that someone is about to modify the page through a
+ * shared-writable mapping
+ */
+static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct file *filp = vma->vm_file;
+	struct inode *inode = file_inode(filp);
+	unsigned pagelen;
+	int ret = VM_FAULT_NOPAGE;
+	struct address_space *mapping;
+
+	dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n",
+		filp, filp->f_mapping->host->i_ino,
+		(long long)page_offset(page));
+
+	/* make sure the cache has finished storing the page */
+	nfs_fscache_wait_on_page_write(NFS_I(inode), page);
+
+	wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
+			nfs_wait_bit_killable, TASK_KILLABLE);
+
+	lock_page(page);
+	mapping = page_file_mapping(page);
+	if (mapping != inode->i_mapping)
+		goto out_unlock;
+
+	wait_on_page_writeback(page);
+
+	pagelen = nfs_page_length(page);
+	if (pagelen == 0)
+		goto out_unlock;
+
+	ret = VM_FAULT_LOCKED;
+	if (nfs_flush_incompatible(filp, page) == 0 &&
+	    nfs_updatepage(filp, page, 0, pagelen) == 0)
+		goto out;
+
+	ret = VM_FAULT_SIGBUS;
+out_unlock:
+	unlock_page(page);
+out:
+	return ret;
+}
+
+static const struct vm_operations_struct nfs_file_vm_ops = {
+	.fault = filemap_fault,
+	.map_pages = filemap_map_pages,
+	.page_mkwrite = nfs_vm_page_mkwrite,
+};
+
+static int nfs_need_sync_write(struct file *filp, struct inode *inode)
+{
+	struct nfs_open_context *ctx;
+
+	if (IS_SYNC(inode) || (filp->f_flags & O_DSYNC))
+		return 1;
+	ctx = nfs_file_open_context(filp);
+	if (test_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags) ||
+	    nfs_ctx_key_to_expire(ctx))
+		return 1;
+	return 0;
+}
+
+ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct inode *inode = file_inode(file);
+	unsigned long written = 0;
+	ssize_t result;
+	size_t count = iov_iter_count(from);
+
+	result = nfs_key_timeout_notify(file, inode);
+	if (result)
+		return result;
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		result = generic_write_checks(iocb, from);
+		if (result <= 0)
+			return result;
+		return nfs_file_direct_write(iocb, from);
+	}
+
+	dprintk("NFS: write(%pD2, %zu@%Ld)\n",
+		file, count, (long long) iocb->ki_pos);
+
+	result = -EBUSY;
+	if (IS_SWAPFILE(inode))
+		goto out_swapfile;
+	/*
+	 * O_APPEND implies that we must revalidate the file length.
+	 */
+	if (iocb->ki_flags & IOCB_APPEND) {
+		result = nfs_revalidate_file_size(inode, file);
+		if (result)
+			goto out;
+	}
+
+	result = count;
+	if (!count)
+		goto out;
+
+	result = generic_file_write_iter(iocb, from);
+	if (result > 0)
+		written = result;
+
+	/* Return error values for O_DSYNC and IS_SYNC() */
+	if (result >= 0 && nfs_need_sync_write(file, inode)) {
+		int err = vfs_fsync(file, 0);
+		if (err < 0)
+			result = err;
+	}
+	if (result > 0)
+		nfs_add_stats(inode, NFSIOS_NORMALWRITTENBYTES, written);
+out:
+	return result;
+
+out_swapfile:
+	printk(KERN_INFO "NFS: attempt to write to active swap file!\n");
+	goto out;
+}
+EXPORT_SYMBOL_GPL(nfs_file_write);
+
+static int
+do_getlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
+{
+	struct inode *inode = filp->f_mapping->host;
+	int status = 0;
+	unsigned int saved_type = fl->fl_type;
+
+	/* Try local locking first */
+	posix_test_lock(filp, fl);
+	if (fl->fl_type != F_UNLCK) {
+		/* found a conflict */
+		goto out;
+	}
+	fl->fl_type = saved_type;
+
+	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
+		goto out_noconflict;
+
+	if (is_local)
+		goto out_noconflict;
+
+	status = NFS_PROTO(inode)->lock(filp, cmd, fl);
+out:
+	return status;
+out_noconflict:
+	fl->fl_type = F_UNLCK;
+	goto out;
+}
+
+static int do_vfs_lock(struct file *file, struct file_lock *fl)
+{
+	int res = 0;
+	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
+		case FL_POSIX:
+			res = posix_lock_file_wait(file, fl);
+			break;
+		case FL_FLOCK:
+			res = flock_lock_file_wait(file, fl);
+			break;
+		default:
+			BUG();
+	}
+	return res;
+}
+
+static int
+do_unlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
+{
+	struct inode *inode = filp->f_mapping->host;
+	struct nfs_lock_context *l_ctx;
+	int status;
+
+	/*
+	 * Flush all pending writes before doing anything
+	 * with locks..
+	 */
+	vfs_fsync(filp, 0);
+
+	l_ctx = nfs_get_lock_context(nfs_file_open_context(filp));
+	if (!IS_ERR(l_ctx)) {
+		status = nfs_iocounter_wait(&l_ctx->io_count);
+		nfs_put_lock_context(l_ctx);
+		if (status < 0)
+			return status;
+	}
+
+	/* NOTE: special case
+	 * 	If we're signalled while cleaning up locks on process exit, we
+	 * 	still need to complete the unlock.
+	 */
+	/*
+	 * Use local locking if mounted with "-onolock" or with appropriate
+	 * "-olocal_lock="
+	 */
+	if (!is_local)
+		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
+	else
+		status = do_vfs_lock(filp, fl);
+	return status;
+}
+
+static int
+is_time_granular(struct timespec *ts) {
+	return ((ts->tv_sec == 0) && (ts->tv_nsec <= 1000));
+}
+
+static int
+do_setlk(struct file *filp, int cmd, struct file_lock *fl, int is_local)
+{
+	struct inode *inode = filp->f_mapping->host;
+	int status;
+
+	/*
+	 * Flush all pending writes before doing anything
+	 * with locks..
+	 */
+	status = nfs_sync_mapping(filp->f_mapping);
+	if (status != 0)
+		goto out;
+
+	/*
+	 * Use local locking if mounted with "-onolock" or with appropriate
+	 * "-olocal_lock="
+	 */
+	if (!is_local)
+		status = NFS_PROTO(inode)->lock(filp, cmd, fl);
+	else
+		status = do_vfs_lock(filp, fl);
+	if (status < 0)
+		goto out;
+
+	/*
+	 * Revalidate the cache if the server has time stamps granular
+	 * enough to detect subsecond changes.  Otherwise, clear the
+	 * cache to prevent missing any changes.
+	 *
+	 * This makes locking act as a cache coherency point.
+	 */
+	nfs_sync_mapping(filp->f_mapping);
+	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ)) {
+		if (is_time_granular(&NFS_SERVER(inode)->time_delta))
+			__nfs_revalidate_inode(NFS_SERVER(inode), inode);
+		else
+			nfs_zap_caches(inode);
+	}
+out:
+	return status;
+}
+
+/*
+ * Lock a (portion of) a file
+ */
+int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
+{
+	struct inode *inode = filp->f_mapping->host;
+	int ret = -ENOLCK;
+	int is_local = 0;
+
+	dprintk("NFS: lock(%pD2, t=%x, fl=%x, r=%lld:%lld)\n",
+			filp, fl->fl_type, fl->fl_flags,
+			(long long)fl->fl_start, (long long)fl->fl_end);
+
+	nfs_inc_stats(inode, NFSIOS_VFSLOCK);
+
+	/* No mandatory locks over NFS */
+	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
+		goto out_err;
+
+	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FCNTL)
+		is_local = 1;
+
+	if (NFS_PROTO(inode)->lock_check_bounds != NULL) {
+		ret = NFS_PROTO(inode)->lock_check_bounds(fl);
+		if (ret < 0)
+			goto out_err;
+	}
+
+	if (IS_GETLK(cmd))
+		ret = do_getlk(filp, cmd, fl, is_local);
+	else if (fl->fl_type == F_UNLCK)
+		ret = do_unlk(filp, cmd, fl, is_local);
+	else
+		ret = do_setlk(filp, cmd, fl, is_local);
+out_err:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nfs_lock);
+
+/*
+ * Lock a (portion of) a file
+ */
+int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
+{
+	struct inode *inode = filp->f_mapping->host;
+	int is_local = 0;
+
+	dprintk("NFS: flock(%pD2, t=%x, fl=%x)\n",
+			filp, fl->fl_type, fl->fl_flags);
+
+	if (!(fl->fl_flags & FL_FLOCK))
+		return -ENOLCK;
+
+	/*
+	 * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
+	 * any standard. In principle we might be able to support LOCK_MAND
+	 * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
+	 * NFS code is not set up for it.
+	 */
+	if (fl->fl_type & LOCK_MAND)
+		return -EINVAL;
+
+	if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
+		is_local = 1;
+
+	/* We're simulating flock() locks using posix locks on the server */
+	if (fl->fl_type == F_UNLCK)
+		return do_unlk(filp, cmd, fl, is_local);
+	return do_setlk(filp, cmd, fl, is_local);
+}
+EXPORT_SYMBOL_GPL(nfs_flock);
+
+const struct file_operations nfs_file_operations = {
+	.llseek		= nfs_file_llseek,
+	.read_iter	= nfs_file_read,
+	.write_iter	= nfs_file_write,
+	.mmap		= nfs_file_mmap,
+	.open		= nfs_file_open,
+	.flush		= nfs_file_flush,
+	.release	= nfs_file_release,
+	.fsync		= nfs_file_fsync,
+	.lock		= nfs_lock,
+	.flock		= nfs_flock,
+	.splice_read	= nfs_file_splice_read,
+	.splice_write	= iter_file_splice_write,
+	.check_flags	= nfs_check_flags,
+	.setlease	= simple_nosetlease,
+};
+EXPORT_SYMBOL_GPL(nfs_file_operations);