Re: [PATCH 1/2] iomap: support tail packing inline read
From: Christoph Hellwig <hch@infradead.org>
Date: 2021-07-19 11:22:02
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On Sat, Jul 17, 2021 at 09:38:18PM +0800, Gao Xiang wrote:
quoted
From 62f367245492e389711bcebbf7da5adae586299f Mon Sep 17 00:00:00 2001From: Christoph Hellwig <hch@lst.de> Date: Fri, 16 Jul 2021 10:52:48 +0200 Subject: [PATCH] iomap: support tail packing inline read
I'd still credit this to you as you did all the hard work.
+ /* inline source data must be inside a single page */ + BUG_ON(iomap->length > PAGE_SIZE - offset_in_page(iomap->inline_data)); + /* handle tail-packing blocks cross the current page into the next */ + if (size > PAGE_SIZE - poff) + size = PAGE_SIZE - poff;
This should probably use min or min_t.
addr = kmap_atomic(page); - memcpy(addr, iomap->inline_data, size); - memset(addr + size, 0, PAGE_SIZE - size); + memcpy(addr + poff, iomap->inline_data - iomap->offset + pos, size); + memset(addr + poff + size, 0, PAGE_SIZE - poff - size); kunmap_atomic(addr); - SetPageUptodate(page); + flush_dcache_page(page);
The flush_dcache_page addition should be a separate patch.
quoted hunk ↗ jump to hunk
if (dio->flags & IOMAP_DIO_WRITE) { loff_t size = inode->i_size;@@ -394,7 +395,8 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length, mark_inode_dirty(inode); } } else { - copied = copy_to_iter(iomap->inline_data + pos, length, iter); + copied = copy_to_iter(iomap->inline_data + pos - iomap->offset, + length, iter);
We also need to take the offset into account for the write side. I guess it would be nice to have a local variable for the inline address to not duplicate that calculation multiple times.