From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH] fadvise: introduce POSIX_FADV_DONTNEED_FS Date: Wed, 27 Apr 2011 17:00:12 +0200 Message-ID: <201104271700.13013.arnd@arndb.de> References: <1303914545-15642-1-git-send-email-andrea@betterlinux.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1303914545-15642-1-git-send-email-andrea@betterlinux.com> Sender: linux-kernel-owner@vger.kernel.org To: Andrea Righi Cc: Andrew Morton , Dave Chinner , Mike Frysinger , Al Viro , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-api@vger.kernel.org On Wednesday 27 April 2011 16:29:05 Andrea Righi wrote: > diff --git a/include/linux/fadvise.h b/include/linux/fadvise.h > index e8e7471..dc9ce98 100644 > --- a/include/linux/fadvise.h > +++ b/include/linux/fadvise.h > @@ -13,9 +13,11 @@ > #if defined(__s390x__) > #define POSIX_FADV_DONTNEED 6 /* Don't need these pages. */ > #define POSIX_FADV_NOREUSE 7 /* Data will be accessed once. */ > +#define POSIX_FADV_DONTNEED_FS 8 /* Don't need these filesystem pages. */ > #else > #define POSIX_FADV_DONTNEED 4 /* Don't need these pages. */ > #define POSIX_FADV_NOREUSE 5 /* Data will be accessed once. */ > +#define POSIX_FADV_DONTNEED_FS 6 /* Don't need these filesystem pages. */ > #endif > > #endif /* FADVISE_H_INCLUDED */ Please don't make the s390 mess worse than it already is here. I think the best solution would be to assign new values starting from 8 so they can be common for all architectures. > @@ -127,6 +128,12 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice) > invalidate_mapping_pages(mapping, start_index, > end_index); > break; > + case POSIX_FADV_DONTNEED_FS: > + if (!current_euid()) > + drop_pagecache_sb(file->f_dentry->d_sb, NULL); > + else > + ret = -EPERM; > + break; I somewhat disagree with keying the capability off the UID value, even if that is what the sysctl uses. CAP_SYS_ADMIN is not that nice either, but I think it's better than the UID here. Aside from these, I like the patch. Arnd