Messages in this thread | | | From | Daeho Jeong <> | Date | Tue, 8 Dec 2020 12:59:00 +0900 | Subject | Re: [f2fs-dev] [PATCH v2 1/2] f2fs: add compress_mode mount option |
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compression enabled regular files have different formats of node metadata on disk. So, using the "compress_mode=user,compress_extension=*" mount option, we want to make the metadata of files ready for compression and make them compressed whenever the user wants using new ioctls.
2020년 12월 8일 (화) 오후 12:51, Eric Biggers <ebiggers@kernel.org>님이 작성: > > On Tue, Dec 01, 2020 at 01:08:02PM +0900, Daeho Jeong wrote: > > From: Daeho Jeong <daehojeong@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 <daehojeong@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
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