From: Theodore Ts'o Subject: Re: [v15 4/4] ext4: cleanup inode flag definitions Date: Mon, 28 Dec 2015 10:23:34 -0500 Message-ID: <20151228152334.GA31415@thunk.org> References: <1442146833-13652-1-git-send-email-lixi@ddn.com> <1442146833-13652-5-git-send-email-lixi@ddn.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, adilger-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org, jack-AlSwsSmVLrQ@public.gmane.org, viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, dmonakhov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org To: Li Xi Return-path: Content-Disposition: inline In-Reply-To: <1442146833-13652-5-git-send-email-lixi-LfVdkaOWEx8@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Sun, Sep 13, 2015 at 09:20:33PM +0900, Li Xi wrote: > The inode flags defined in uapi/linux/fs.h were migrated from > ext4.h. This patch changes the inode flag definitions in ext4.h > to VFS definitions to make the gaps between them clearer. > > Signed-off-by: Li Xi > Reviewed-by: Andreas Dilger Instead of doing things this way, I've decided to clean things up by updating the flags in uapi/linux/fs.h. That's because some people who might want to assign new flags might not be ext4 developers, and so they wouldn't look at fs/ext4/ext4.h. At the same time, we really don't want people adding new flags by default, unless there is a really good reason. So I've added a comment making the history of the interface and suggesting that people not assign new flags without thinking twice (or checking with linux-fsdevel and linux-api). - Ted commit 6ac40c7b5597646ec4335f77ab79cac9663f4a1e Author: Theodore Ts'o Date: Mon Dec 28 10:21:43 2015 -0500 fs: clean up the flags definition in uapi/linux/fs.h Add an explanation for the flags used by FS_IOC_[GS]ETFLAGS and remind people that changes should be revised by linux-fsdevel and linux-api. Add flags that are used on-disk for ext4, and remove FS_DIRECTIO_FL since it was used only by gfs2 and support was removed in 2008 in commit c9f6a6bbc28 ("The ability to mark files for direct i/o access when opened normally is both unused and pointless, so this patch removes support for that feature.") Now we have _two_ remaining flags left. But since we want to discourage people from assigning new flags, that's OK. Signed-off-by: Theodore Ts'o diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 627f58e..35d156f 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -2,8 +2,11 @@ #define _UAPI_LINUX_FS_H /* - * This file has definitions for some important file table - * structures etc. + * This file has definitions for some important file table structures + * and constants and structures used by various generic file system + * ioctl's. Please do not make any changes in this file before + * sending patches for review to linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org and + * linux-api-u79uwXL29TaiAVqoAR/hOA@public.gmane.org */ #include @@ -204,6 +207,23 @@ struct fsxattr { /* * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS) + * + * Note: for historical reasons, these flags were originally used and + * defined for use by ext2/ext3, and then other file systems started + * using these flags so they wouldn't need to write their own version + * of chattr/lsattr (which was shipped as part of e2fsprogs). You + * should think twice before trying to use these flags in new + * contexts, or trying to assign these flags, since they are used both + * as the UAPI and the on-disk encoding for ext2/3/4. Also, we are + * almost out of 32-bit flags. :-) + * + * We have recently hoisted FS_IOC_FSGETXATTR / FS_IOC_FSSETXATTR from + * XFS to the generic FS level interface. This uses a structure that + * has padding and hence has more room to grow, so it may be more + * appropriate for many new use cases. + * + * Please do not change these flags or interfaces before checking with + * linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org and linux-api-u79uwXL29TaiAVqoAR/hOA@public.gmane.org */ #define FS_SECRM_FL 0x00000001 /* Secure deletion */ #define FS_UNRM_FL 0x00000002 /* Undelete */ @@ -217,8 +237,8 @@ struct fsxattr { #define FS_DIRTY_FL 0x00000100 #define FS_COMPRBLK_FL 0x00000200 /* One or more compressed clusters */ #define FS_NOCOMP_FL 0x00000400 /* Don't compress */ -#define FS_ECOMPR_FL 0x00000800 /* Compression error */ /* End compression flags --- maybe not all used */ +#define FS_ENCRYPT_FL 0x00000800 /* Encrypted file */ #define FS_BTREE_FL 0x00001000 /* btree format dir */ #define FS_INDEX_FL 0x00001000 /* hash-indexed directory */ #define FS_IMAGIC_FL 0x00002000 /* AFS directory */ @@ -226,9 +246,12 @@ struct fsxattr { #define FS_NOTAIL_FL 0x00008000 /* file tail should not be merged */ #define FS_DIRSYNC_FL 0x00010000 /* dirsync behaviour (directories only) */ #define FS_TOPDIR_FL 0x00020000 /* Top of directory hierarchies*/ +#define FS_HUGE_FILE_FL 0x00040000 /* Reserved for ext4 */ #define FS_EXTENT_FL 0x00080000 /* Extents */ -#define FS_DIRECTIO_FL 0x00100000 /* Use direct i/o */ +#define FS_EA_INODE_FL 0x00200000 /* Inode used for large EA */ +#define FS_EOFBLOCKS_FL 0x00400000 /* Reserved for ext4 */ #define FS_NOCOW_FL 0x00800000 /* Do not cow file */ +#define FS_INLINE_DATA_FL 0x10000000 /* Reserved for ext4 */ #define FS_PROJINHERIT_FL 0x20000000 /* Create with parents projid */ #define FS_RESERVED_FL 0x80000000 /* reserved for ext2 lib */