[PATCH 2/2] mm: implement ->fault_nonblock() for page cache

From: Kirill A. Shutemov <hidden>
Date: 2014-02-17 18:38:53
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, 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, Trond Myklebust, Anna Schumaker, Ryusuke Konishi, Viacheslav Dubeyko, Matthew Wilcox, Linus Torvalds, Richard Weinberger, Carlos Maiolino

filemap_fault_nonblock() is generic implementation of ->fault_nonblock()
for filesystems who uses page cache.

It should be safe to use filemap_fault_nonblock() for ->fault_nonblock()
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 +
 mm/filemap.c      | 35 +++++++++++++++++++++++++++++++++++
 12 files changed, 47 insertions(+)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index a16b0ff497ca..a7f7e41bec37 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,
+	.fault_nonblock = filemap_fault_nonblock,
 	.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,
+	.fault_nonblock = filemap_fault_nonblock,
 	.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..13523a63e1f3 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,
+	.fault_nonblock	= filemap_fault_nonblock,
 	.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..71aff75e067c 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,
+	.fault_nonblock = filemap_fault_nonblock,
 	.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..182ae5543a1d 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,
+	.fault_nonblock	= filemap_fault_nonblock,
 	.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..7c48fd2eb99c 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,
+	.fault_nonblock	= filemap_fault_nonblock,
 	.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..e95e52ec7bc2 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,
+	.fault_nonblock	= filemap_fault_nonblock,
 	.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..7c4b2f096ac8 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,
+	.fault_nonblock = filemap_fault_nonblock,
 	.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..8fbe80168d1f 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,
+	.fault_nonblock = filemap_fault_nonblock,
 	.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..adc4aa07d7d8 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,
+	.fault_nonblock	= filemap_fault_nonblock,
 	.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..f27c4c401a3f 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,
+	.fault_nonblock = filemap_fault_nonblock,
 	.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..bc619150c960 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,
+	.fault_nonblock	= filemap_fault_nonblock,
 	.page_mkwrite	= xfs_vm_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

diff --git a/mm/filemap.c b/mm/filemap.c
index 7a13f6ac5421..7b7c9c600544 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c

@@ -1726,6 +1726,40 @@ page_not_uptodate:
 }
 EXPORT_SYMBOL(filemap_fault);
 
+void filemap_fault_nonblock(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct file *file = vma->vm_file;
+	struct address_space *mapping = file->f_mapping;
+	pgoff_t size;
+	struct page *page;
+
+	page = find_get_page(mapping, vmf->pgoff);
+	if (!page)
+		return;
+	if (PageReadahead(page) || PageHWPoison(page))
+		goto put;
+	if (!trylock_page(page))
+		goto put;
+	/* Truncated? */
+	if (unlikely(page->mapping != mapping))
+		goto unlock;
+	if (unlikely(!PageUptodate(page)))
+		goto unlock;
+	size = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1)
+		>> PAGE_CACHE_SHIFT;
+	if (unlikely(page->index >= size))
+		goto unlock;
+	if (file->f_ra.mmap_miss > 0)
+		file->f_ra.mmap_miss--;
+	vmf->page = page;
+	return;
+unlock:
+	unlock_page(page);
+put:
+	put_page(page);
+}
+EXPORT_SYMBOL(filemap_fault_nonblock);
+
 int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct page *page = vmf->page;

@@ -1755,6 +1789,7 @@ EXPORT_SYMBOL(filemap_page_mkwrite);
 
 const struct vm_operations_struct generic_file_vm_ops = {
 	.fault		= filemap_fault,
+	.fault_nonblock	= filemap_fault_nonblock,
 	.page_mkwrite	= filemap_page_mkwrite,
 	.remap_pages	= generic_file_remap_pages,
 };

-- 
1.9.0.rc3

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

`h`	back out one level
`j`	next message in thread
`k`	previous message in thread
`l`	drill in
`Esc`	close help / fold thread tree
`?`	toggle this help