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Commit d44ed4f8 authored by Paolo 'Blaisorblade' Giarrusso's avatar Paolo 'Blaisorblade' Giarrusso Committed by Linus Torvalds
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[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: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 0abf40c1

mm/filemap.c

+7 −0
Original line number Diff line number Diff line
@@ -1504,8 +1504,12 @@ int filemap_populate(struct vm_area_struct *vma, unsigned long addr, 
		return -EINVAL;



	page = filemap_getpage(file, pgoff, nonblock);



	/* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as

	 * done in shmem_populate calling shmem_getpage */

	if (!page && !nonblock)

		return -ENOMEM;



	if (page) {

		err = install_page(mm, vma, addr, page, prot);

		if (err) {
@@ -1513,6 +1517,9 @@ int filemap_populate(struct vm_area_struct *vma, unsigned long addr, 
			return err;

		}

	} 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;

mm/shmem.c

+5 −1
Original line number Diff line number Diff line
@@ -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;