Messages in this thread | | | Date | Sat, 17 Jul 2021 23:15:58 +0800 | From | Gao Xiang <> | Subject | Re: [PATCH 1/2] iomap: support tail packing inline read |
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Hi Matthew,
On Sat, Jul 17, 2021 at 04:01:38PM +0100, Matthew Wilcox wrote: > On Sat, Jul 17, 2021 at 09:38:18PM +0800, Gao Xiang wrote: > > Sorry about some late. I've revised a version based on Christoph's > > version and Matthew's thought above. I've preliminary checked with > > EROFS, if it does make sense, please kindly help check on the gfs2 > > side as well.. > > I don't understand how this bit works:
This part inherited from the Christoph version without change. The following thoughts are just my own understanding...
> > > struct page *page = ctx->cur_page; > > - struct iomap_page *iop; > > + struct iomap_page *iop = NULL; > > bool same_page = false, is_contig = false; > > loff_t orig_pos = pos; > > unsigned poff, plen; > > sector_t sector; > > > > - if (iomap->type == IOMAP_INLINE) { > > - WARN_ON_ONCE(pos); > > - iomap_read_inline_data(inode, page, iomap); > > - return PAGE_SIZE; > > - } > > + if (iomap->type == IOMAP_INLINE && !pos) > > + WARN_ON_ONCE(to_iomap_page(page) != NULL); > > + else > > + iop = iomap_page_create(inode, page); > > Imagine you have a file with bytes 0-2047 in an extent which is !INLINE > and bytes 2048-2051 in the INLINE extent. When you read the page, first > you create an iop for the !INLINE extent. Then this function is called
Yes, it first created an iop for the !INLINE extent.
> again for the INLINE extent and you'll hit the WARN_ON_ONCE. No?
If it is called again with another INLINE extent, pos will be non-0? so (!pos) == false. Am I missing something?
Thanks, Gao Xiang
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