Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-08-05 Thread Christoph Hellwig
On Tue, Aug 01, 2017 at 12:42:18PM +1000, Dave Chinner wrote: > I've outlined other use cases in previous discussions. To repeat > myself, every so often we get someone with, say, a new high > speed camera that want to dma the camera frames direct to the > storage because they can't push 500,000 fr

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Dave Chinner
On Mon, Jul 31, 2017 at 10:15:12PM -0400, Colin Walters wrote: > On Mon, Jul 31, 2017, at 02:23 PM, Darrick J. Wong wrote: > > > I don't think F_SEAL_{SHRINK,GROW} prevents reflinking or CoW of file data, > > which are two things that cannot happen under S_IOMAP_IMMUTABLE that > > aren't size chan

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Colin Walters
On Mon, Jul 31, 2017, at 02:23 PM, Darrick J. Wong wrote: > I don't think F_SEAL_{SHRINK,GROW} prevents reflinking or CoW of file data, > which are two things that cannot happen under S_IOMAP_IMMUTABLE that > aren't size changes. From the implementation it looks like shrink and > grow are only su

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Darrick J. Wong
On Mon, Jul 31, 2017 at 01:42:13PM -0400, Colin Walters wrote: > > > On Mon, Jul 31, 2017, at 12:32 PM, Colin Walters wrote: > > On Mon, Jul 31, 2017, at 12:29 PM, Dan Williams wrote: > > > > > > How is S_CONTENTS_IMMUTABLE different than S_IMMUTABLE? > > > > We still want the ability to make h

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Colin Walters
On Mon, Jul 31, 2017, at 12:32 PM, Colin Walters wrote: > On Mon, Jul 31, 2017, at 12:29 PM, Dan Williams wrote: > > > > How is S_CONTENTS_IMMUTABLE different than S_IMMUTABLE? > > We still want the ability to make hardlinks. Also of course, symmetrically, to unlink. If we used S_IMMUTABLE f

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Dan Williams
On Mon, Jul 31, 2017 at 9:46 AM, Darrick J. Wong wrote: > On Sat, Jul 29, 2017 at 12:43:35PM -0700, Dan Williams wrote: >> An inode with this flag set indicates that the file's block map cannot >> be changed, no size change, deletion, hole-punch, range collapse, or >> reflink. >> >> The implementa

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Darrick J. Wong
On Sat, Jul 29, 2017 at 12:43:35PM -0700, Dan Williams wrote: > An inode with this flag set indicates that the file's block map cannot > be changed, no size change, deletion, hole-punch, range collapse, or > reflink. > > The implementation of toggling the flag and sealing the state of the > extent

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Colin Walters
On Mon, Jul 31, 2017, at 12:29 PM, Dan Williams wrote: > > How is S_CONTENTS_IMMUTABLE different than S_IMMUTABLE? We still want the ability to make hardlinks.

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Dan Williams
On Mon, Jul 31, 2017 at 9:02 AM, Colin Walters wrote: > On Sat, Jul 29, 2017, at 03:43 PM, Dan Williams wrote: >> An inode with this flag set indicates that the file's block map cannot >> be changed, no size change, deletion, hole-punch, range collapse, or >> reflink. >> >> The implementation of t

Re: [PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-31 Thread Colin Walters
On Sat, Jul 29, 2017, at 03:43 PM, Dan Williams wrote: > An inode with this flag set indicates that the file's block map cannot > be changed, no size change, deletion, hole-punch, range collapse, or > reflink. > > The implementation of toggling the flag and sealing the state of the > extent map is

[PATCH 1/3] fs, xfs: introduce S_IOMAP_IMMUTABLE

2017-07-29 Thread Dan Williams
An inode with this flag set indicates that the file's block map cannot be changed, no size change, deletion, hole-punch, range collapse, or reflink. The implementation of toggling the flag and sealing the state of the extent map is saved for a later patch. The functionality provided by S_IOMAP_IMM