On Fri, 2008-02-22 at 20:09 +0530, Aneesh Kumar K.V wrote:
We would like to get notified when we are doing a write on mmap section.
This is needed with respect to preallocated area. We split the preallocated
area into initialzed extent and uninitialzed extent in the call back. This
let us handle ENOSPC better. Otherwise we get ENOSPC in the writepage and
that would result in data loss. The changes are also needed to handle ENOSPC
when writing to an mmap section of files with holes.
Signed-off-by: Aneesh Kumar K.V [EMAIL PROTECTED]
---
fs/ext4/file.c | 19 ++-
fs/ext4/inode.c | 60
+++
include/linux/ext4_fs.h |1 +
3 files changed, 79 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 20507a2..77341c1 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -123,6 +123,23 @@ force_commit:
return ret;
}
+static struct vm_operations_struct ext4_file_vm_ops = {
+ .fault = filemap_fault,
+ .page_mkwrite = ext4_page_mkwrite,
+};
+
+static int ext4_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 = ext4_file_vm_ops;
+ vma-vm_flags |= VM_CAN_NONLINEAR;
+ return 0;
+}
+
const struct file_operations ext4_file_operations = {
.llseek = generic_file_llseek,
.read = do_sync_read,
@@ -133,7 +150,7 @@ const struct file_operations ext4_file_operations = {
#ifdef CONFIG_COMPAT
.compat_ioctl = ext4_compat_ioctl,
#endif
- .mmap = generic_file_mmap,
+ .mmap = ext4_file_mmap,
.open = generic_file_open,
.release= ext4_release_file,
.fsync = ext4_sync_file,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5b5d63d..00af97d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3490,3 +3490,63 @@ int ext4_change_inode_journal_flag(struct inode
*inode, int val)
return err;
}
+
+int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page)
+{
+ unsigned long end;
+ loff_t size;
+ handle_t *handle;
+ int ret = -EINVAL, needed_blocks;
+ struct file *file = vma-vm_file;
+ struct inode *inode = file-f_path.dentry-d_inode;
+
+ needed_blocks = ext4_writepage_trans_blocks(inode);
+ /* We need to take inode mutex to prevent parallel write */
+ mutex_lock(inode-i_mutex);
+ lock_page(page);
+ size = i_size_read(inode);
+ if ((page-mapping != inode-i_mapping) ||
+ (page_offset(page) size)) {
+ /* page got truncated out from underneath us */
+ goto out_unlock;
+ }
+
+ /* page is wholly or partially inside EOF */
+ if (((page-index + 1) PAGE_CACHE_SHIFT) size)
+ end = size ~PAGE_CACHE_MASK;
+ else
+ end = PAGE_CACHE_SIZE;
+
+ handle = ext4_journal_start(inode, needed_blocks);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out_unlock;
+ }
+ /* Will zero out the pages if buffer is marked new */
+ ret = block_prepare_write(page, 0, end, ext4_get_block);
+
+ if (!ret ext4_should_journal_data(inode)) {
+ ret = walk_page_buffers(handle, page_buffers(page),
+ 0, end, NULL, do_journal_get_write_access);
+ if (!ret)
+ ret = walk_page_buffers(handle, page_buffers(page),
+ 0, end, NULL, write_end_fn);
+ /*
+ * we don't want to call block_commit_write in journalled mode
+ */
+ ext4_journal_stop(handle);
+ goto out_unlock;
+ }
+ if (!ret ext4_should_order_data(inode)) {
+ ret = walk_page_buffers(handle, page_buffers(page),
+ 0, end, NULL, ext4_journal_dirty_data);
+ }
+ if (!ret)
+ ret = block_commit_write(page, 0, end);
+
Hmm, it seems wired to do commit_write when the page is about becoming
writable, but maybe that's the way it needs to?
Don't we need to update the i_size somewhere?
+ ext4_journal_stop(handle);
+out_unlock:
+ unlock_page(page);
+ mutex_unlock(inode-i_mutex);
+ return ret;
+}
It seems this combined the three journalling mode prepare_write() code
here:(
Since prepare_write() and commit_write() is going to sunset, why not
simply calling mappings-a_ops-write_begin() and then write_end()? that
should take care of pretty much the journalling and the page operations,
no?
Mingming
diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index 22810b1..8f5a563 100644
--- a/include/linux/ext4_fs.h
+++
