From f4e6b498d6e06742d72706ef50593a9c4dd72214 Mon Sep 17 00:00:00 2001 From: Fengguang Wu <wfg@mail.ustc.edu.cn> Date: Tue, 16 Oct 2007 01:24:33 -0700 Subject: readahead: combine file_ra_state.prev_index/prev_offset into prev_pos Combine the file_ra_state members unsigned long prev_index unsigned int prev_offset into loff_t prev_pos It is more consistent and better supports huge files. Thanks to Peter for the nice proposal! [akpm@linux-foundation.org: fix shift overflow] Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- mm/filemap.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index 5dc18d76e703..bbcca456d8a6 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -879,8 +879,8 @@ void do_generic_mapping_read(struct address_space *mapping, cached_page = NULL; index = *ppos >> PAGE_CACHE_SHIFT; next_index = index; - prev_index = ra.prev_index; - prev_offset = ra.prev_offset; + prev_index = ra.prev_pos >> PAGE_CACHE_SHIFT; + prev_offset = ra.prev_pos & (PAGE_CACHE_SIZE-1); last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; offset = *ppos & ~PAGE_CACHE_MASK; @@ -966,7 +966,6 @@ page_ok: index += offset >> PAGE_CACHE_SHIFT; offset &= ~PAGE_CACHE_MASK; prev_offset = offset; - ra.prev_offset = offset; page_cache_release(page); if (ret == nr && desc->count) @@ -1056,9 +1055,11 @@ no_cached_page: out: *_ra = ra; - _ra->prev_index = prev_index; + _ra->prev_pos = prev_index; + _ra->prev_pos <<= PAGE_CACHE_SHIFT; + _ra->prev_pos |= prev_offset; - *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; + *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset; if (cached_page) page_cache_release(cached_page); if (filp) @@ -1396,7 +1397,7 @@ retry_find: * Found the page and have a reference on it. */ mark_page_accessed(page); - ra->prev_index = page->index; + ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT; vmf->page = page; return ret | VM_FAULT_LOCKED; -- cgit v1.2.3-70-g09d2