From: Christoph Hellwig <hch@lst.de>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org,
darrick.wong@oracle.com, hch@lst.de, linux-xfs@vger.kernel.org,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 04/15] btrfs: Add a simple buffered iomap write
Date: Thu, 5 Sep 2019 18:23:44 +0200 [thread overview]
Message-ID: <20190905162344.GA22450@lst.de> (raw)
In-Reply-To: <20190905150650.21089-5-rgoldwyn@suse.de>
> Most of the code is "inspired" by
> fs/btrfs/file.c. To keep the size small, all removals are in
> following patches.
Wouldn't it be better to massage the existing code into a form where you
can fairly easily switch over to iomap? That is start refactoring the
code into helpers that are mostly reusable and then just have a patch
switching over. That helps reviewing what actually changes. It's
also what we did for XFS.
> + if (!ordered) {
> + break;
> + }
No need for the braces.
> +static void btrfs_buffered_page_done(struct inode *inode, loff_t pos,
> + unsigned copied, struct page *page,
> + struct iomap *iomap)
> +{
> + if (!page)
> + return;
> + SetPageUptodate(page);
> + ClearPageChecked(page);
> + set_page_dirty(page);
> + get_page(page);
> +}
Thіs looks really strange. Can you explain me why you need the
manual dirtying and SetPageUptodate, and an additional page refcount
here?
> + if (ret < 0) {
> + /*
> + * Space allocation failed. Let's check if we can
> + * continue I/O without allocations
> + */
> + if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
> + BTRFS_INODE_PREALLOC)) &&
> + check_can_nocow(BTRFS_I(inode), pos,
> + &write_bytes) > 0) {
> + bi->nocow = true;
> + /*
> + * our prealloc extent may be smaller than
> + * write_bytes, so scale down.
> + */
> + bi->reserved_bytes = round_up(write_bytes +
> + sector_offset,
> + fs_info->sectorsize);
> + } else {
> + goto error;
> + }
Maybe move the goto into the inverted if so you can reduce indentation
by one level?
> + } else {
> + u64 __pos = round_down(pos + written, fs_info->sectorsize);
Line over > 80 characters, and a somewhat odd variabke name.
> + if (bi->nocow) {
> + struct btrfs_root *root = BTRFS_I(inode)->root;
> + btrfs_end_write_no_snapshotting(root);
> + if (written > 0) {
> + u64 start = round_down(pos, fs_info->sectorsize);
> + u64 end = round_up(pos + written, fs_info->sectorsize) - 1;
Line > 80 chars.
> + set_extent_bit(&BTRFS_I(inode)->io_tree, start, end,
> + EXTENT_NORESERVE, NULL, NULL, GFP_NOFS);
> + }
> +
> + }
> + btrfs_delalloc_release_extents(BTRFS_I(inode), bi->reserved_bytes,
> + true);
> +
> + if (written < fs_info->nodesize)
> + btrfs_btree_balance_dirty(fs_info);
> +
> + extent_changeset_free(bi->data_reserved);
> + kfree(bi);
> + return ret;
> +}
> +static const struct iomap_ops btrfs_buffered_iomap_ops = {
> + .iomap_begin = btrfs_buffered_iomap_begin,
> + .iomap_end = btrfs_buffered_iomap_end,
> +};
> +
> +size_t btrfs_buffered_iomap_write(struct kiocb *iocb, struct iov_iter *from)
> +{
> + ssize_t written;
> + struct inode *inode = file_inode(iocb->ki_filp);
> + written = iomap_file_buffered_write(iocb, from, &btrfs_buffered_iomap_ops);
no empty line after the variable declarations? Also this adds a > 80
character line.
> + if (written > 0)
> + iocb->ki_pos += written;
I wonder if we should fold the ki_pos update into
iomap_file_buffered_write. But the patch looks fine even without that.
Also any reason to not name this function btrfs_buffered_write and
keep it in file.c with the rest of the write code?
next prev parent reply other threads:[~2019-09-05 16:23 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 15:06 [PATCH v4 0/15] CoW support for iomap Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 01/15] iomap: Use a srcmap for a read-modify-write I/O Goldwyn Rodrigues
2019-09-05 23:23 ` Darrick J. Wong
2019-09-05 15:06 ` [PATCH 02/15] iomap: Read page from srcmap if IOMAP_F_COW is set Goldwyn Rodrigues
2019-09-05 16:37 ` Christoph Hellwig
2019-09-05 20:28 ` Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 03/15] btrfs: Eliminate PagePrivate for btrfs data pages Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 04/15] btrfs: Add a simple buffered iomap write Goldwyn Rodrigues
2019-09-05 16:23 ` Christoph Hellwig [this message]
2019-09-05 20:42 ` Goldwyn Rodrigues
2019-09-06 5:54 ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 05/15] btrfs: Add CoW in iomap based writes Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 06/15] btrfs: remove buffered write code made unnecessary Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 07/15] fs: Export generic_file_buffered_read() Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 08/15] btrfs: basic direct read operation Goldwyn Rodrigues
2019-09-05 16:25 ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 09/15] btrfs: Carve out btrfs_get_extent_map_write() out of btrfs_get_blocks_write() Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 10/15] btrfs: Rename __endio_write_update_ordered() to btrfs_update_ordered_extent() Goldwyn Rodrigues
2019-09-05 15:06 ` [PATCH 11/15] iomap: use a function pointer for dio submits Goldwyn Rodrigues
2019-09-05 16:27 ` Christoph Hellwig
2019-09-05 23:24 ` Darrick J. Wong
2019-09-05 15:06 ` [PATCH 12/15] btrfs: Use iomap_dio_rw for performing direct I/O writes Goldwyn Rodrigues
2019-09-05 16:31 ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 13/15] btrfs: Remove btrfs_dio_data and __btrfs_direct_write Goldwyn Rodrigues
2019-09-05 16:32 ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 14/15] btrfs: update inode size during bio completion Goldwyn Rodrigues
2019-09-05 16:33 ` Christoph Hellwig
2019-09-05 15:06 ` [PATCH 15/15] xfs: Use the new iomap infrastructure for CoW Goldwyn Rodrigues
2019-09-06 16:55 ` Christoph Hellwig
2019-09-06 23:28 ` Dave Chinner
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