Messages in this thread Patch in this message | | | Subject | [patch 02/39] shmem_populate: avoid an useless check, and some comments | From | blaisorblade@yahoo ... | Date | Fri, 12 Aug 2005 20:20:59 +0200 |
| |
From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
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.
References: commit b103e8b204b317d52834671d5f09db95645523c2 of old-2.6-bkcvs, pointing to BKrev: 3f5ed0c1llm6NnNwNXtPv-Z0IYzkwA
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> ---
linux-2.6.git-paolo/mm/filemap.c | 7 +++++++ linux-2.6.git-paolo/mm/shmem.c | 6 +++++- 2 files changed, 12 insertions(+), 1 deletion(-)
diff -puN mm/shmem.c~mm-populate-optim-comment mm/shmem.c --- linux-2.6.git/mm/shmem.c~mm-populate-optim-comment 2005-08-11 11:12:39.000000000 +0200 +++ linux-2.6.git-paolo/mm/shmem.c 2005-08-11 11:12:39.000000000 +0200 @@ -1195,6 +1195,7 @@ static int shmem_populate(struct vm_area 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 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; diff -puN mm/filemap.c~mm-populate-optim-comment mm/filemap.c --- linux-2.6.git/mm/filemap.c~mm-populate-optim-comment 2005-08-11 11:12:39.000000000 +0200 +++ linux-2.6.git-paolo/mm/filemap.c 2005-08-11 11:12:39.000000000 +0200 @@ -1505,8 +1505,12 @@ repeat: 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) { @@ -1514,6 +1518,9 @@ repeat: 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; _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |