From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm/readahead: add DEFINE_READAHEAD Patch series "Readahead patches for 5.9/5.10". These are infrastructure for both the THP patchset and for the fscache rewrite, For both pieces of infrastructure being build on top of this patchset, we want the ractl to be available higher in the call-stack. For David's work, he wants to add the 'critical page' to the ractl so that he knows which page NEEDS to be brought in from storage, and which ones are nice-to-have. We might want something similar in block storage too. It used to be simple -- the first page was the critical one, but then mmap added fault-around and so for that usecase, the middle page is the critical one. Anyway, I don't have any code to show that yet, we just know that the lowest point in the callchain where we have that information is do_sync_mmap_readahead() and so the ractl needs to start its life there. For THP, we havew the code that needs it. It's actually the apex patch to the series; the one which finally starts to allocate THPs and present them to consenting filesystems: http://git.infradead.org/users/willy/pagecache.git/commitdiff/798bcf30ab2eff278caad03a9edca74d2f8ae760 This patch (of 8): Allow for a more concise definition of a struct readahead_control. Link: https://lkml.kernel.org/r/20200903140844.14194-1-willy@xxxxxxxxxxxxx Link: https://lkml.kernel.org/r/20200903140844.14194-3-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Eric Biggers <ebiggers@xxxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/pagemap.h | 7 +++++++ mm/readahead.c | 6 +----- 2 files changed, 8 insertions(+), 5 deletions(-) --- a/include/linux/pagemap.h~mm-readahead-add-define_readahead +++ a/include/linux/pagemap.h @@ -812,6 +812,13 @@ struct readahead_control { unsigned int _batch_count; }; +#define DEFINE_READAHEAD(rac, f, m, i) \ + struct readahead_control rac = { \ + .file = f, \ + .mapping = m, \ + ._index = i, \ + } + /** * readahead_page - Get the next page to read. * @rac: The current readahead request. --- a/mm/readahead.c~mm-readahead-add-define_readahead +++ a/mm/readahead.c @@ -179,11 +179,7 @@ void page_cache_readahead_unbounded(stru { LIST_HEAD(page_pool); gfp_t gfp_mask = readahead_gfp_mask(mapping); - struct readahead_control rac = { - .mapping = mapping, - .file = file, - ._index = index, - }; + DEFINE_READAHEAD(rac, file, mapping, index); unsigned long i; /* _
