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 <lixi@xxxxxxx>
> Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
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 <tytso@xxxxxxx>
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 <tytso@xxxxxxx>
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@xxxxxxxxxxxxxxx and
+ * linux-api@xxxxxxxxxxxxxxx.
*/
#include <linux/limits.h>
@@ -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@xxxxxxxxxxxxxxx and linux-api@xxxxxxxxxxxxxxx.
*/
#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 */
--
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