On 06/20/2012 02:33 PM, KOSAKI Motohiro wrote: > (6/20/12 2:31 AM), Wanlong Gao wrote: >> 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 ? > > They are checked in force_page_cache_readahead. I see, thank you. Reviewed-by: Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx> > > -- 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>