[PATCHv3 2/2] mm: implement ->map_pages for page cache

From: Kirill A. Shutemov <hidden>
Date: 2014-02-27 19:53:47
Also in: linux-fsdevel, lkml
Subsystem: 9p file system, btrfs file system, ext4 file system, f2fs file system, filesystems (vfs and infrastructure), fuse filesystem [core], gfs2 file system, memory management, memory management - core, memory mapping, nfs, sunrpc, and lockd clients, nilfs2 filesystem, page cache, the rest, ubi file system (ubifs), xfs filesystem · Maintainers: Eric Van Hensbergen, Latchesar Ionkov, Dominique Martinet, Chris Mason, David Sterba, "Theodore Ts'o", Jaegeuk Kim, Chao Yu, Alexander Viro, Christian Brauner, Miklos Szeredi, Andreas Gruenbacher, Andrew Morton, David Hildenbrand, Liam R. Howlett, Lorenzo Stoakes, Trond Myklebust, Anna Schumaker, Ryusuke Konishi, Viacheslav Dubeyko, Matthew Wilcox, Jan Kara, Linus Torvalds, Richard Weinberger, Carlos Maiolino

filemap_map_pages() is generic implementation of ->map_pages() for
filesystems who uses page cache.

It should be safe to use filemap_map_pages() for ->map_pages() if
filesystem use filemap_fault() for ->fault().

Signed-off-by: Kirill A. Shutemov <redacted>
---
 fs/9p/vfs_file.c   |  2 ++
 fs/btrfs/file.c    |  1 +
 fs/cifs/file.c     |  1 +
 fs/ext4/file.c     |  1 +
 fs/f2fs/file.c     |  1 +
 fs/fuse/file.c     |  1 +
 fs/gfs2/file.c     |  1 +
 fs/nfs/file.c      |  1 +
 fs/nilfs2/file.c   |  1 +
 fs/ubifs/file.c    |  1 +
 fs/xfs/xfs_file.c  |  1 +
 include/linux/mm.h |  1 +
 mm/filemap.c       | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 mm/nommu.c         |  6 +++++
 14 files changed, 91 insertions(+)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index a16b0ff497ca..d8223209d4b1 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c

@@ -832,6 +832,7 @@ static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
 
 static const struct vm_operations_struct v9fs_file_vm_ops = {
 	.fault = filemap_fault,
+	.map_pages = filemap_map_pages,
 	.page_mkwrite = v9fs_vm_page_mkwrite,
 	.remap_pages = generic_file_remap_pages,
 };

@@ -839,6 +840,7 @@ static const struct vm_operations_struct v9fs_file_vm_ops = {
 static const struct vm_operations_struct v9fs_mmap_file_vm_ops = {
 	.close = v9fs_mmap_vm_close,
 	.fault = filemap_fault,
+	.map_pages = filemap_map_pages,
 	.page_mkwrite = v9fs_vm_page_mkwrite,
 	.remap_pages = generic_file_remap_pages,
 };

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 0165b8672f09..d1f0415bbfb1 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c

@@ -1993,6 +1993,7 @@ out:
 
 static const struct vm_operations_struct btrfs_file_vm_ops = {
 	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= btrfs_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 755584684f6c..6d081de57fdb 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c

@@ -3094,6 +3094,7 @@ cifs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 
 static struct vm_operations_struct cifs_file_vm_ops = {
 	.fault = filemap_fault,
+	.map_pages = filemap_map_pages,
 	.page_mkwrite = cifs_page_mkwrite,
 	.remap_pages = generic_file_remap_pages,
 };

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1a5073959f32..46e78f8a133f 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c

@@ -200,6 +200,7 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 
 static const struct vm_operations_struct ext4_file_vm_ops = {
 	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
 	.page_mkwrite   = ext4_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 0dfcef53a6ed..129a3bdb05ca 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c

@@ -84,6 +84,7 @@ out:
 
 static const struct vm_operations_struct f2fs_file_vm_ops = {
 	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= f2fs_vm_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 77bcc303c3ae..da99a76668f8 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c

@@ -1940,6 +1940,7 @@ static int fuse_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 static const struct vm_operations_struct fuse_file_vm_ops = {
 	.close		= fuse_vma_close,
 	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= fuse_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index efc078f0ee4e..2739f3c3bb8f 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c

@@ -494,6 +494,7 @@ out:
 
 static const struct vm_operations_struct gfs2_vm_ops = {
 	.fault = filemap_fault,
+	.map_pages = filemap_map_pages,
 	.page_mkwrite = gfs2_page_mkwrite,
 	.remap_pages = generic_file_remap_pages,
 };

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 5bb790a69c71..284ca901fe16 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c

@@ -617,6 +617,7 @@ out:
 
 static const struct vm_operations_struct nfs_file_vm_ops = {
 	.fault = filemap_fault,
+	.map_pages = filemap_map_pages,
 	.page_mkwrite = nfs_vm_page_mkwrite,
 	.remap_pages = generic_file_remap_pages,
 };

diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
index 08fdb77852ac..f3a82fbcae02 100644
--- a/fs/nilfs2/file.c
+++ b/fs/nilfs2/file.c

@@ -134,6 +134,7 @@ static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 
 static const struct vm_operations_struct nilfs_file_vm_ops = {
 	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= nilfs_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 123c79b7261e..4f34dbae823d 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c

@@ -1538,6 +1538,7 @@ out_unlock:
 
 static const struct vm_operations_struct ubifs_file_vm_ops = {
 	.fault        = filemap_fault,
+	.map_pages = filemap_map_pages,
 	.page_mkwrite = ubifs_vm_page_mkwrite,
 	.remap_pages = generic_file_remap_pages,
 };

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 64b48eade91d..b2be204e16ca 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c

@@ -1465,6 +1465,7 @@ const struct file_operations xfs_dir_file_operations = {
 
 static const struct vm_operations_struct xfs_file_vm_ops = {
 	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= xfs_vm_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/include/linux/mm.h b/include/linux/mm.h
index aed92cb17127..7c4bfb725e63 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h

@@ -1818,6 +1818,7 @@ extern void truncate_inode_pages_range(struct address_space *,
 
 /* generic vm_area_ops exported for stackable file systems */
 extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
+extern void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf);
 extern int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
 
 /* mm/page-writeback.c */

diff --git a/mm/filemap.c b/mm/filemap.c
index 7a13f6ac5421..1bc12a96060d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c

@@ -33,6 +33,7 @@
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
 #include <linux/memcontrol.h>
 #include <linux/cleancache.h>
+#include <linux/rmap.h>
 #include "internal.h"
 
 #define CREATE_TRACE_POINTS

@@ -1726,6 +1727,76 @@ page_not_uptodate:
 }
 EXPORT_SYMBOL(filemap_fault);
 
+void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct radix_tree_iter iter;
+	void **slot;
+	struct file *file = vma->vm_file;
+	struct address_space *mapping = file->f_mapping;
+	loff_t size;
+	struct page *page;
+	unsigned long address = (unsigned long) vmf->virtual_address;
+	unsigned long addr;
+	pte_t *pte;
+
+	rcu_read_lock();
+	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, vmf->pgoff) {
+		if (iter.index > vmf->max_pgoff)
+			break;
+repeat:
+		page = radix_tree_deref_slot(slot);
+		if (radix_tree_exception(page)) {
+			if (radix_tree_deref_retry(page))
+				break;
+			else
+				goto next;
+		}
+
+		if (!page_cache_get_speculative(page))
+			goto repeat;
+
+		/* Has the page moved? */
+		if (unlikely(page != *slot)) {
+			page_cache_release(page);
+			goto repeat;
+		}
+
+		if (!PageUptodate(page) ||
+				PageReadahead(page) ||
+				PageHWPoison(page))
+			goto skip;
+		if (!trylock_page(page))
+			goto skip;
+
+		if (page->mapping != mapping || !PageUptodate(page))
+			goto unlock;
+
+		size = i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1;
+		if (page->index >= size	>> PAGE_CACHE_SHIFT)
+			goto unlock;
+
+		pte = vmf->pte + page->index - vmf->pgoff;
+		if (!pte_none(*pte))
+			goto unlock;
+
+		if (file->f_ra.mmap_miss > 0)
+			file->f_ra.mmap_miss--;
+		addr = address + (page->index - vmf->pgoff) * PAGE_SIZE;
+		do_set_pte(vma, addr, page, pte, false, false);
+		unlock_page(page);
+		goto next;
+unlock:
+		unlock_page(page);
+skip:
+		page_cache_release(page);
+next:
+		if (page->index == vmf->max_pgoff)
+			break;
+	}
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(filemap_map_pages);
+
 int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct page *page = vmf->page;

@@ -1755,6 +1826,7 @@ EXPORT_SYMBOL(filemap_page_mkwrite);
 
 const struct vm_operations_struct generic_file_vm_ops = {
 	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
 	.page_mkwrite	= filemap_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/mm/nommu.c b/mm/nommu.c
index 8740213b1647..ce401e37e29f 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c

@@ -1985,6 +1985,12 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 }
 EXPORT_SYMBOL(filemap_fault);
 
+void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	BUG();
+}
+EXPORT_SYMBOL(filemap_map_pages);
+
 int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
 			     unsigned long size, pgoff_t pgoff)
 {

-- 
1.9.0

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