On 2/18/20 2:57 PM, John Hubbard wrote: > On 2/17/20 10:45 AM, Matthew Wilcox wrote: >> From: "Matthew Wilcox (Oracle)" <wi...@infradead.org> >> >> Eliminate the page_offset variable which was just confusing; >> record the start of each consecutive run of pages in the > >
Darn it, I incorrectly reviewed the N/16 patch, instead of the N/19, for this one. I thought I had deleted all those! Let me try again with the correct patch, sorry!! thanks, -- John Hubbard NVIDIA > OK...presumably for the benefit of a following patch, since it is not > actually consumed in this patch. > >> readahead_control, and move the 'kick off a fresh batch' code to >> the end of the function for easier use in the next patch. > > > That last bit was actually done in the previous patch, rather than this > one, right? > >> >> Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org> >> --- >> mm/readahead.c | 31 +++++++++++++++++++------------ >> 1 file changed, 19 insertions(+), 12 deletions(-) >> >> diff --git a/mm/readahead.c b/mm/readahead.c >> index 15329309231f..74791b96013f 100644 >> --- a/mm/readahead.c >> +++ b/mm/readahead.c >> @@ -154,7 +154,6 @@ void __do_page_cache_readahead(struct address_space >> *mapping, >> unsigned long lookahead_size) >> { >> struct inode *inode = mapping->host; >> - struct page *page; >> unsigned long end_index; /* The last page we want to read */ >> LIST_HEAD(page_pool); >> int page_idx; >> @@ -163,6 +162,7 @@ void __do_page_cache_readahead(struct address_space >> *mapping, >> struct readahead_control rac = { >> .mapping = mapping, >> .file = filp, >> + ._start = offset, >> ._nr_pages = 0, >> }; >> >> @@ -175,32 +175,39 @@ void __do_page_cache_readahead(struct address_space >> *mapping, >> * Preallocate as many pages as we will need. >> */ >> for (page_idx = 0; page_idx < nr_to_read; page_idx++) { >> - pgoff_t page_offset = offset + page_idx; > > > You know...this ends up incrementing offset each time through the > loop, so yes, the behavior is the same as when using "offset + page_idx". > However, now it's a little harder to see that. > > IMHO the page_offset variable is not actually a bad thing, here. I'd rather > keep it, all other things being equal (and I don't see any other benefits > here: line count is the same, for example). > > What do you think? > > > thanks, >