[PATCH 03/11] ext2: Allocate space for mmaped file on page fault

Jan Kara
2009-06-15T18:01:23Z

So far we've allocated space at ->writepage() time. This has the disadvantage
that when we hit ENOSPC or other error, we cannot do much - either throw
away the data or keep the page indefinitely (and loose the data on reboot).
So allocate space already when a page is faulted in.

Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/ext2/file.c | 26 +++++++++++++++++++++++++-
fs/ext2/inode.c | 1 +
2 files changed, 26 insertions(+), 1 deletions(-)

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 2b9e47d..d0a5f13 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -19,6 +19,8 @@
*/

#include <linux/time.h>
+#include <linux/mm.h>
+#include <linux/buffer_head.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
@@ -38,6 +40,28 @@ static int ext2_release_file (struct inode * inode, struct file * filp)
return 0;
}

+static int ext2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return block_page_mkwrite(vma, vmf, ext2_get_block);
+}
+
+static struct vm_operations_struct ext2_file_vm_ops = {
+ .fault = filemap_fault,
+ .page_mkwrite = ext2_page_mkwrite,
+};
+
+static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct address_space *mapping = file->f_mapping;
+
+ if (!mapping->a_ops->readpage)
+ return -ENOEXEC;
+ file_accessed(file);
+ vma->vm_ops = &ext2_file_vm_ops;
+ vma->vm_flags |= VM_CAN_NONLINEAR;
+ return 0;
+}
+
/*
* We have mostly NULL's here: the current defaults are ok for
* the ext2 filesystem.
@@ -52,7 +76,7 @@ const struct file_operations ext2_file_operations = {
#ifdef CONFIG_COMPAT
.compat_ioctl = ext2_compat_ioctl,
#endif
- .mmap = generic_file_mmap,
+ .mmap = ext2_file_mmap,
.open = generic_file_open,
.release = ext2_release_file,
.fsync = simple_fsync,
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 29ed682..3805b6b 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -814,6 +814,7 @@ const struct address_space_operations ext2_aops = {
.sync_page = block_sync_page,
.write_begin = ext2_write_begin,
.write_end = generic_write_end,
+ .extend_i_size = block_extend_i_size,
.bmap = ext2_bmap,
.direct_IO = ext2_direct_IO,
.writepages = ext2_writepages,
--
1.6.0.2