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Message-ID: <Y4+r2c+d+gWi93og@casper.infradead.org> Date: Tue, 6 Dec 2022 20:53:45 +0000 From: Matthew Wilcox <willy@...radead.org> To: "Vishal Moola (Oracle)" <vishal.moola@...il.com> Cc: linux-mm@...ck.org, tytso@....edu, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, akpm@...ux-foundation.org Subject: Re: [PATCH mm-unstable] ext4: Convert mext_page_double_lock() to mext_folio_double_lock() On Tue, Dec 06, 2022 at 08:50:02PM +0000, Matthew Wilcox wrote: > > flags = memalloc_nofs_save(); > > - page[0] = grab_cache_page_write_begin(mapping[0], index1); > > - if (!page[0]) { > > + folio[0] = __filemap_get_folio(mapping[0], index1, fgp_flags, > > + mapping_gfp_mask(mapping[0])); > > one > > > + if (!folio[0]) { > > memalloc_nofs_restore(flags); > > return -ENOMEM; > > } > > > > - page[1] = grab_cache_page_write_begin(mapping[1], index2); > > + folio[1] = __filemap_get_folio(mapping[1], index2, fgp_flags, > > + mapping_gfp_mask(mapping[1])); > > two *facepalm*. Those don't contain calls to compound_head(), they contain calls to folio_file_page(), which is still a moderately-expensive unnecessary conversion, but a conversion in the other direction.
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