From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-erofs@lists.ozlabs.org
Subject: Re: [PATCH 2/2] iomap: Support inline data with block size < page size
Date: Sat, 24 Jul 2021 15:52:20 +0800 [thread overview]
Message-ID: <YPvGtP89rmiy9sU0@B-P7TQMD6M-0146.local> (raw)
In-Reply-To: <YPug7VUMZboQu4QW@B-P7TQMD6M-0146.local>
On Sat, Jul 24, 2021 at 01:11:09PM +0800, Gao Xiang wrote:
> On Sat, Jul 24, 2021 at 12:46:45PM +0800, Gao Xiang wrote:
...
> >
> > Thanks for the patch!
> >
> > Previously I'd like to skip the leading uptodate blocks and update the
> > extent it covers that is due to already exist iop. If we get rid of the
> > offset_in_page(pos) restriction like this, I'm not sure if we (or some
> > other fs users) could face something like below (due to somewhat buggy
> > fs users likewise):
> >
> > [0 - 4096) plain block
> >
> > [4096 - 4608) tail INLINE 1 (e.g. by mistake or just splitted
> > .iomap_begin() report.)
> > [4608 - 5120] tail INLINE 2
> >
>
> (cont.)
>
> So I think without the !offset_in_page(pos) restriction, at least we
> may need to add something like:
>
> if (WARN_ON_ONCE(size != i_size_read(inode) - iomap->offset))
> return -EIO;
>
> to the approach to detect such cases at least but that is no need with
> page-sized and !offset_in_page(pos) restriction.
>
Never mind, after rethinking with clear head, I think I was overthinking
this part and it shouldn't behave like this. Sorry about the noise above.
> >
> > >
> > > - addr = kmap_atomic(page);
> > > + addr = kmap_atomic(page) + poff;
> > > memcpy(addr, iomap_inline_buf(iomap, pos), size);
> > > - memset(addr + size, 0, PAGE_SIZE - size);
> > > + memset(addr + size, 0, PAGE_SIZE - poff - size);
> > > kunmap_atomic(addr);
> >
> > As my limited understanding, this may need to be fixed, since it
> > doesn't match kmap_atomic(page)...
> >
> > Thanks,
> > Gao Xiang
> >
> > > - SetPageUptodate(page);
> > > - return PAGE_SIZE;
> > > + iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff);
> > > + return PAGE_SIZE - poff;
> > > }
> > >
> > > static inline bool iomap_block_needs_zeroing(struct inode *inode,
> > > --
> > > 2.30.2
> > >
next prev parent reply other threads:[~2021-07-24 7:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-24 3:44 [PATCH 0/2] iomap: make inline data support more flexible Matthew Wilcox (Oracle)
2021-07-24 3:44 ` [PATCH 1/2] iomap: Support file tail packing Matthew Wilcox (Oracle)
2021-07-24 3:44 ` [PATCH 2/2] iomap: Support inline data with block size < page size Matthew Wilcox (Oracle)
2021-07-24 4:46 ` Gao Xiang
2021-07-24 5:11 ` Gao Xiang
2021-07-24 7:52 ` Gao Xiang [this message]
2021-07-24 14:03 ` Matthew Wilcox
2021-07-24 15:14 ` Gao Xiang
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