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; - } - /* 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; -- 1.7.1 -- 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>