linux-ext4 - [PATCH] ext3: Use page_mkwrite vma_operations to get mmap write notification.

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Date:	Mon, 24 Mar 2008 22:34:56 +0530
From:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:	cmm@...ibm.com, akpm@...ux-foundation.org
Cc:	linux-ext4@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH] ext3: Use page_mkwrite vma_operations to get mmap write notification.

We would like to get notified when we are doing a write on mmap section.
The changes are needed to handle ENOSPC when writing to an mmap section
of files with holes.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
---
 fs/ext3/file.c          |   19 ++++++++++++++++++-
 fs/ext3/inode.c         |    5 +++++
 include/linux/ext3_fs.h |    1 +
 3 files changed, 24 insertions(+), 1 deletions(-)

diff --git a/fs/ext3/file.c b/fs/ext3/file.c
index acc4913..09e22e4 100644
--- a/fs/ext3/file.c
+++ b/fs/ext3/file.c
@@ -106,6 +106,23 @@ force_commit:
 	return ret;
 }
 
+static struct vm_operations_struct ext3_file_vm_ops = {
+	.fault		= filemap_fault,
+	.page_mkwrite   = ext3_page_mkwrite,
+};
+
+static int ext3_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 = &ext3_file_vm_ops;
+	vma->vm_flags |= VM_CAN_NONLINEAR;
+	return 0;
+}
+
 const struct file_operations ext3_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= do_sync_read,
@@ -116,7 +133,7 @@ const struct file_operations ext3_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext3_compat_ioctl,
 #endif
-	.mmap		= generic_file_mmap,
+	.mmap		= ext3_file_mmap,
 	.open		= generic_file_open,
 	.release	= ext3_release_file,
 	.fsync		= ext3_sync_file,
diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index eb95670..2293506 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -3306,3 +3306,8 @@ int ext3_change_inode_journal_flag(struct inode *inode, int val)
 
 	return err;
 }
+
+int ext3_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+{
+	return block_page_mkwrite(vma, page, ext3_get_block);
+}
diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
index 36c5403..715c35e 100644
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -836,6 +836,7 @@ extern void ext3_truncate (struct inode *);
 extern void ext3_set_inode_flags(struct inode *);
 extern void ext3_get_inode_flags(struct ext3_inode_info *);
 extern void ext3_set_aops(struct inode *inode);
+extern int ext3_page_mkwrite(struct vm_area_struct *vma, struct page *page);
 
 /* ioctl.c */
 extern int ext3_ioctl (struct inode *, struct file *, unsigned int,
-- 
1.5.5.rc0.16.g02b00.dirty

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