On Tue, Dec 01, 2020 at 01:08:02PM +0900, Daeho Jeong wrote: > From: Daeho Jeong <daehoje...@google.com> > > We will add a new "compress_mode" mount option to control file > compression mode. This supports "fs" and "user". In "fs" mode (default), > f2fs does automatic compression on the compression enabled files. > In "user" mode, f2fs disables the automaic compression and gives the > user discretion of choosing the target file and the timing. It means > the user can do manual compression/decompression on the compression > enabled files using ioctls. > > Signed-off-by: Daeho Jeong <daehoje...@google.com> > --- > v2: changed mount option name and added more explanation of mount option > --- > Documentation/filesystems/f2fs.rst | 35 ++++++++++++++++++++++++++++++ > fs/f2fs/compress.c | 2 +- > fs/f2fs/data.c | 2 +- > fs/f2fs/f2fs.h | 30 +++++++++++++++++++++++++ > fs/f2fs/segment.c | 2 +- > fs/f2fs/super.c | 23 ++++++++++++++++++++ > 6 files changed, 91 insertions(+), 3 deletions(-) > > diff --git a/Documentation/filesystems/f2fs.rst > b/Documentation/filesystems/f2fs.rst > index b8ee761c9922..5eb8d63439ec 100644 > --- a/Documentation/filesystems/f2fs.rst > +++ b/Documentation/filesystems/f2fs.rst > @@ -260,6 +260,13 @@ compress_extension=%s Support adding specified > extension, so that f2fs can enab > For other files, we can still enable compression via > ioctl. > Note that, there is one reserved special extension > '*', it > can be set to enable compression for all files. > +compress_mode=%s Control file compression mode. This supports "fs" and > "user" > + modes. In "fs" mode (default), f2fs does automatic > compression > + on the compression enabled files. In "user" mode, f2fs > disables > + the automaic compression and gives the user discretion > of > + choosing the target file and the timing. The user can > do manual > + compression/decompression on the compression enabled > files using > + ioctls. > inlinecrypt When possible, encrypt/decrypt the contents of > encrypted > files using the blk-crypto framework rather than > filesystem-layer encryption. This allows the use of > @@ -810,6 +817,34 @@ Compress metadata layout:: > | data length | data chksum | reserved | compressed data | > +-------------+-------------+----------+----------------------------+ > > +Compression mode > +-------------------------- > + > +f2fs supports "fs" and "user" compression modes with "compression_mode" > mount option. > +With this option, f2fs provides a choice to select the way how to compress > the > +compression enabled files (refer to "Compression implementation" section for > how to > +enable compression on a regular inode). > + > +1) compress_mode=fs > +This is the default option. f2fs does automatic compression in the writeback > of the > +compression enabled files. > + > +2) compress_mode=user > +This disables the automaic compression and gives the user discretion of > choosing the > +target file and the timing. The user can do manual compression/decompression > on the > +compression enabled files using F2FS_IOC_DECOMPRESS_FILE and > F2FS_IOC_COMPRESS_FILE > +ioctls like the below. > + > +To decompress a file, > + > +fd = open(filename, O_WRONLY, 0); > +ret = ioctl(fd, F2FS_IOC_DECOMPRESS_FILE); > + > +To compress a file, > + > +fd = open(filename, O_WRONLY, 0); > +ret = ioctl(fd, F2FS_IOC_COMPRESS_FILE); > +
Why doesn't compress_mode=user just cause regular files to not inherit the compression flag? Then users could set or clear the compression flag using FS_IOC_SETFLAGS, without any need for these new ioctls. - Eric
