Hi,
On Sun, 2006-04-23 at 01:55 -0600, Andreas Dilger wrote:
> On Apr 21, 2006 17:13 +0100, Steven Whitehouse wrote:
> > This also includes a new header file, iflags.h which is designed to
> > abstract the (originally ext2 only, but now used by many different fs)
> > get/set flags ioctl by having one central place in which to register
> > filesystem flags. Given favourable reviews, I'll submit some patches to
> > update the other fileststems to define their flags in terms of those
> > in iflags.h. Note that this doesn't change the interface of the other
> > filesystems since the values of the flags are identical to those
> > previously defined.
> >
> > To the best of my knowledge, GFS2 is the only filesystem which requires
> > the addition of flags above and beyond those defined by ext2/3 so if
> > there are others and we've clashed with them, please let me know.
>
> > --- /dev/null
> > +++ b/include/linux/iflags.h
> > @@ -0,0 +1,104 @@
[some constants snipped for brevity]
> > +
> > +#define __IFL(x) (1<<(iflag_##x))
> > +#define IFLAG_SECRM __IFL(SecureRm) /* 0x00000001 */
> > +#define IFLAG_UNRM __IFL(Unrm) /* 0x00000002 */
> > +#define IFLAG_COMPR __IFL(Compr) /* 0x00000004 */
> > +#define IFLAG_SYNC __IFL(Sync) /* 0x00000008 */
> > +#define IFLAG_IMMUTABLE __IFL(Immutable) /* 0x00000010 */
> > +#define IFLAG_APPEND __IFL(Append) /* 0x00000020 */
> > +#define IFLAG_NODUMP __IFL(NoDump) /* 0x00000040 */
> > +#define IFLAG_NOATIME __IFL(NoAtime) /* 0x00000080 */
> > +#define IFLAG_DIRTY __IFL(Dirty) /* 0x00000100 */
> > +#define IFLAG_COMPRBLK __IFL(ComprBlk) /* 0x00000200 */
> > +#define IFLAG_NOCOMP __IFL(NoComp) /* 0x00000400 */
> > +#define IFLAG_ECOMPR __IFL(Ecompr) /* 0x00000800 */
> > +#define IFLAG_BTREE __IFL(Btree) /* 0x00001000 */
> > +#define IFLAG_INDEX __IFL(Index) /* 0x00001000 */
> > +#define IFLAG_IMAGIC __IFL(Imagic) /* 0x00002000 */
> > +#define IFLAG_JOURNAL_DATA __IFL(JournalData) /* 0x00004000 */
> > +#define IFLAG_NOTAIL __IFL(NoTail) /* 0x00008000 */
> > +#define IFLAG_DIRSYNC __IFL(DirSync) /* 0x00010000 */
> > +#define IFLAG_TOPDIR __IFL(TopDir) /* 0x00020000 */
> > +#define IFLAG_DIRECTIO __IFL(DirectIO) /* 0x00040000 */
> > +#define IFLAG_INHERITDIRECTIO __IFL(InheritDirectIO) /* 0x00080000 */
> > +#define IFLAG_INHERITJDATA __IFL(InheritJdata) /* 0x00100000 */
> > +#define IFLAG_RESERVED __IFL(Reserved) /* 0x80000000 */
>
> Actually, the 0x0080000 flag has been reserved by e2fsprogs for ext3
> extents for a while already. AFAICS, there are no other flags in the
> current e2fsprogs that aren't listed above.
>
So if I call that one IFLAG_EXTENT, then I presume that will be ok?
What about the 0x00040000 flag? That would seem to be a gap in the
sequence (ignoring GFS flags for now), so should I leave that reserved
for use by ext2/3 as well?
> The other tidbit is that new ext2/ext3 files generally inherit the flags
> from their parent directory, so it isn't clear if there is really a need
> for a distinction between DIRECTIO and INHERIT_DIRECTIO, and similarly
> JDATA and INHERIT_JDATA? Generally, I'd think that JDATA isn't meaningful
> on directories (since they are metadata and journaled anyways), nor is
> DIRECTIO so their only meaning on a directory is "INHERIT for new files".
>
> Cheers, Andreas
Yes, that sounds like a good plan. The only downside (purely from a GFS2
point of view, it won't affect anybody else) means that its no longer a
1:1 relationship between flags, so in order to do the conversion, I'd
have to use something a little more elaborate than the inline function I
added to the iflags.h header file,
Steve.
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