Re: [rfc][patch 3/3] fs: convert ext2,tmpfs to new truncate

Christoph Hellwig
2009-07-06T16:50:38Z

On Mon, Jul 06, 2009 at 06:56:29PM +0200, Nick Piggin wrote:
>
> Convert filemap_xip.c, buffer.c, and some filesystems to the new truncate
> convention. Converting generic helpers is using some ugly code (testing
> for i_op->ftruncate) to distinguish new and old callers... better
> alternative might be just define a new function for these guys.

Splitting generic preparations, ext2 and shmem into separate patch would
be a tad cleaner I think.

The testing for the new op is pretty ugly, but this should be just a
transition help, so it's fine to me.

> struct page **pagep, void **fsdata)
> {
> + int ret;
> +
> *pagep = NULL;
> - return __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
> + ret = __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
> + if (ret < 0) {
> + loff_t isize = inode->i_size;
> + if (pos + len > isize)
> + ext2_ftruncate(NULL, 0, inode, isize);
> + }
> + return ret;
> +}
> +
> +static int ext2_write_end(struct file *file, struct address_space *mapping,
> + loff_t pos, unsigned len, unsigned copied,
> + struct page *page, void *fsdata)
> +{
> + int ret;
> +
> + ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
> + if (ret < len) {
> + loff_t isize = inode->i_size;
> + if (pos + len > isize)
> + ext2_ftruncate(NULL, 0, inode, isize);
> + }
> + return ret;
> }
>
> static int
> @@ -770,13 +793,22 @@ ext2_nobh_write_begin(struct file *file,
> loff_t pos, unsigned len, unsigned flags,
> struct page **pagep, void **fsdata)
> {
> + int ret;
> +
> /*
> * Dir-in-pagecache still uses ext2_write_begin. Would have to rework
> * directory handling code to pass around offsets rather than struct
> * pages in order to make this work easily.
> */
> - return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
> + ret = nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
> ext2_get_block);
> + if (ret < 0) {
> + loff_t isize;
> + isize = i_size_read(inode);
> + if (pos + len > isize)
> + ext2_ftruncate(NULL, 0, inode, isize);
> + }
> + return ret;
> }
>
> static int ext2_nobh_writepage(struct page *page,
> @@ -796,9 +828,15 @@ ext2_direct_IO(int rw, struct kiocb *ioc
> {
> struct file *file = iocb->ki_filp;
> struct inode *inode = file->f_mapping->host;
> + ssize_t ret;
>
> - return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
> + ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
> offset, nr_segs, ext2_get_block, NULL);
> + if (ret < 0 && (rw & WRITE)) {
> + loff_t isize = i_size_read(inode);
> + ext2_ftruncate(NULL, 0, inode, isize);

These calls don't actually have i_alloc_mutex anymore, do they?

> {
> - shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
> + loff_t oldsize;
> + int error;
> +
> + error = inode_truncate_ok(inode, offset);
> + if (error)
> + return error;
> + oldsize = inode->i_size;
> + i_size_write(inode, offset);
> + truncate_pagecache(inode, oldsize, offset);
> + shmem_truncate_range(inode, offset, (loff_t)-1);
> +
> + return error;
> }

Just make this

error = simple_ftruncate(...);
if (!error)
shmem_truncate_range(inode, offset, -1);
return error;