On 06/16/2012 04:36 AM, kosaki.motohiro@xxxxxxxxx wrote: > From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > > Eric Wong reported his test suite was fail when /tmp is tmpfs. > > https://lkml.org/lkml/2012/2/24/479 > > Current,input check of POSIX_FADV_WILLNEED has two problems. > > 1) require a_ops->readpage. > But in fact, force_page_cache_readahead() only require > a target filesystem has either ->readpage or ->readpages. > 2) return -EINVAL when filesystem don't have ->readpage. > But, posix says, it should be retrieved a hint. Thus fadvise() > should return 0 if filesystem has no optimization way. > Especially, userland application don't know a filesystem type > of TMPDIR directory as Eric pointed out. Then, userland can't > avoid this error. We shouldn't encourage to ignore syscall > return value. > > Thus, this patch change a return value to 0 when filesytem don't > support readahead. > > Cc: linux-mm@xxxxxxxxx > Cc: Hugh Dickins <hughd@xxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Hillf Danton <dhillf@xxxxxxxxx> > Signed-off-by: Eric Wong <normalperson@xxxxxxxx> > Tested-by: Eric Wong <normalperson@xxxxxxxx> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> > --- > mm/fadvise.c | 18 +++++++----------- > 1 files changed, 7 insertions(+), 11 deletions(-) > > diff --git a/mm/fadvise.c b/mm/fadvise.c > index 469491e..33e6baf 100644 > --- a/mm/fadvise.c > +++ b/mm/fadvise.c > @@ -93,11 +93,6 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice) > spin_unlock(&file->f_lock); > break; > case POSIX_FADV_WILLNEED: > - if (!mapping->a_ops->readpage) { > - ret = -EINVAL; > - break; > - } Why not check both readpage and readpages, if they are not here, just beak and no following force_page_cache_readahead ? Thanks, Wanlong Gao > - > /* First and last PARTIAL page! */ > start_index = offset >> PAGE_CACHE_SHIFT; > end_index = endbyte >> PAGE_CACHE_SHIFT; > @@ -106,12 +101,13 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice) > nrpages = end_index - start_index + 1; > if (!nrpages) > nrpages = ~0UL; > - > - ret = force_page_cache_readahead(mapping, file, > - start_index, > - nrpages); > - if (ret > 0) > - ret = 0; > + > + /* > + * Ignore return value because fadvise() shall return > + * success even if filesystem can't retrieve a hint, > + */ > + force_page_cache_readahead(mapping, file, start_index, > + nrpages); > break; > case POSIX_FADV_NOREUSE: > break; > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>