On Thu, Feb 27, 2025 at 10:51:40AM +0100, Carlos Maiolino wrote: > On Tue, Feb 04, 2025 at 11:39:59AM -0700, Jens Axboe wrote: > > Add iomap buffered write support for RWF_DONTCACHE. If RWF_DONTCACHE is > > set for a write, mark the folios being written as uncached. Then > > writeback completion will drop the pages. The write_iter handler simply > > kicks off writeback for the pages, and writeback completion will take > > care of the rest. > > > > [Adding Brauner to the loop as this usually goes through his tree.] > > Christian, I'm pulling this into my tree for 6.15 if this is ok with you? > Not sure if you're subscribed to linux-xfs, so, just in case, the link for the > whole 2-patches series is below. > > https://lore.kernel.org/linux-xfs/20250204184047.356762-1-axboe@xxxxxxxxx/ vfs-6.15.iomap has a lot of iomap changes already so we should use a shared tree we can both merge. I've put this on: vfs-6.15.shared.iomap Just pull it into your branch, please and I pull it into vfs-6.15.iomap. I see that 2/2 adds a new FOP_UNCACHED flag to the VFS FOP_UNCACHED please make sure to Cc fsdevel for such additions and remind contributors as well. > > > > Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx> > > Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> > > --- > > Documentation/filesystems/iomap/design.rst | 5 +++++ > > Documentation/filesystems/iomap/operations.rst | 2 ++ > > fs/iomap/buffered-io.c | 4 ++++ > > include/linux/iomap.h | 1 + > > 4 files changed, 12 insertions(+) > > > > diff --git a/Documentation/filesystems/iomap/design.rst b/Documentation/filesystems/iomap/design.rst > > index b0d0188a095e..7b91546750f5 100644 > > --- a/Documentation/filesystems/iomap/design.rst > > +++ b/Documentation/filesystems/iomap/design.rst > > @@ -352,6 +352,11 @@ operations: > > ``IOMAP_NOWAIT`` is often set on behalf of ``IOCB_NOWAIT`` or > > ``RWF_NOWAIT``. > > > > + * ``IOMAP_DONTCACHE`` is set when the caller wishes to perform a > > + buffered file I/O and would like the kernel to drop the pagecache > > + after the I/O completes, if it isn't already being used by another > > + thread. > > + > > If it is necessary to read existing file contents from a `different > > <https://lore.kernel.org/all/20191008071527.29304-9-hch@xxxxxx/>`_ > > device or address range on a device, the filesystem should return that > > diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst > > index 2c7f5df9d8b0..584ff549f9a6 100644 > > --- a/Documentation/filesystems/iomap/operations.rst > > +++ b/Documentation/filesystems/iomap/operations.rst > > @@ -131,6 +131,8 @@ These ``struct kiocb`` flags are significant for buffered I/O with iomap: > > > > * ``IOCB_NOWAIT``: Turns on ``IOMAP_NOWAIT``. > > > > + * ``IOCB_DONTCACHE``: Turns on ``IOMAP_DONTCACHE``. > > + > > Internal per-Folio State > > ------------------------ > > > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > index d303e6c8900c..ea863c3cf510 100644 > > --- a/fs/iomap/buffered-io.c > > +++ b/fs/iomap/buffered-io.c > > @@ -603,6 +603,8 @@ struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len) > > > > if (iter->flags & IOMAP_NOWAIT) > > fgp |= FGP_NOWAIT; > > + if (iter->flags & IOMAP_DONTCACHE) > > + fgp |= FGP_DONTCACHE; > > fgp |= fgf_set_order(len); > > > > return __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT, > > @@ -1034,6 +1036,8 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i, > > > > if (iocb->ki_flags & IOCB_NOWAIT) > > iter.flags |= IOMAP_NOWAIT; > > + if (iocb->ki_flags & IOCB_DONTCACHE) > > + iter.flags |= IOMAP_DONTCACHE; > > > > while ((ret = iomap_iter(&iter, ops)) > 0) > > iter.processed = iomap_write_iter(&iter, i); > > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > > index 75bf54e76f3b..26b0dbe23e62 100644 > > --- a/include/linux/iomap.h > > +++ b/include/linux/iomap.h > > @@ -183,6 +183,7 @@ struct iomap_folio_ops { > > #define IOMAP_DAX 0 > > #endif /* CONFIG_FS_DAX */ > > #define IOMAP_ATOMIC (1 << 9) > > +#define IOMAP_DONTCACHE (1 << 10) > > > > struct iomap_ops { > > /* > > -- > > 2.47.2 > >
