From d44ed4f86892e350f4b16a3489b7e7c1a9bb7ead Mon Sep 17 00:00:00 2001 From: Paolo 'Blaisorblade' Giarrusso Date: Sat, 3 Sep 2005 15:54:55 -0700 Subject: [PATCH] shmem_populate: avoid an useless check, and some comments Either shmem_getpage returns a failure, or it found a page, or it was told it couldn't do any I/O. So it's useless to check nonblock in the else branch. We could add a BUG() there but I preferred to comment the offending function. This was taken out from one Ingo Molnar's old patch I'm resurrecting. Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Ingo Molnar Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/shmem.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'mm/shmem.c') diff --git a/mm/shmem.c b/mm/shmem.c index 5a81b1ee4f7..08a3bc2fba6 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1195,6 +1195,7 @@ static int shmem_populate(struct vm_area_struct *vma, err = shmem_getpage(inode, pgoff, &page, sgp, NULL); if (err) return err; + /* Page may still be null, but only if nonblock was set. */ if (page) { mark_page_accessed(page); err = install_page(mm, vma, addr, page, prot); @@ -1202,7 +1203,10 @@ static int shmem_populate(struct vm_area_struct *vma, page_cache_release(page); return err; } - } else if (nonblock) { + } else { + /* No page was found just because we can't read it in + * now (being here implies nonblock != 0), but the page + * may exist, so set the PTE to fault it in later. */ err = install_file_pte(mm, vma, addr, pgoff, prot); if (err) return err; -- cgit v1.2.3