| Message ID | 20210212214949.4408-1-trondmy@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add a mount option to support eager writes | expand |
Hey! On 2/12/21 4:49 PM, trondmy@kernel.org wrote: > From: Trond Myklebust <trond.myklebust@hammerspace.com> > > The following patch series sets up a new mount option > 'writes=lazy/eager/wait'. The mount option basically controls how the > write() system call works. > - writes=lazy is the default, and keeps the current behaviour > - writes=eager means we send off the write immediately as an unstable > write to the server. > - writes=wait means we send off the write as an unstable write, and then > wait for the reply. > > The main motivator for this behaviour is that some applications expect > write() to return ENOSPC. Setting writes=wait should satisfy those > applications without taking the full overhead of a synchronous write. > > writes=eager, on the other hand, can be useful for applications such as > re-exporting NFS, since it would allow knfsd on the proxying server to > immediately forward the writes to the original server. > > Trond Myklebust (3): > NFS: 'flags' field should be unsigned in struct nfs_server > NFS: Add support for eager writes > NFS: Add mount options supporting eager writes > > fs/nfs/file.c | 19 +++++++++++++++++-- > fs/nfs/fs_context.c | 33 +++++++++++++++++++++++++++++++++ > fs/nfs/write.c | 17 ++++++++++++----- > include/linux/nfs_fs_sb.h | 4 +++- > 4 files changed, 65 insertions(+), 8 deletions(-) > Shouldn't something be added to the nfs(5) man page as well as blurb added to /etc/nfsmount.conf file? steved.
On Sat, 2021-02-13 at 09:19 -0500, Steve Dickson wrote: > Hey! > > On 2/12/21 4:49 PM, trondmy@kernel.org wrote: > > From: Trond Myklebust <trond.myklebust@hammerspace.com> > > > > The following patch series sets up a new mount option > > 'writes=lazy/eager/wait'. The mount option basically controls how > > the > > write() system call works. > > - writes=lazy is the default, and keeps the current behaviour > > - writes=eager means we send off the write immediately as an > > unstable > > write to the server. > > - writes=wait means we send off the write as an unstable write, and > > then > > wait for the reply. > > > > The main motivator for this behaviour is that some applications > > expect > > write() to return ENOSPC. Setting writes=wait should satisfy those > > applications without taking the full overhead of a synchronous > > write. > > > > writes=eager, on the other hand, can be useful for applications > > such as > > re-exporting NFS, since it would allow knfsd on the proxying server > > to > > immediately forward the writes to the original server. > > > > Trond Myklebust (3): > > NFS: 'flags' field should be unsigned in struct nfs_server > > NFS: Add support for eager writes > > NFS: Add mount options supporting eager writes > > > > fs/nfs/file.c | 19 +++++++++++++++++-- > > fs/nfs/fs_context.c | 33 +++++++++++++++++++++++++++++++++ > > fs/nfs/write.c | 17 ++++++++++++----- > > include/linux/nfs_fs_sb.h | 4 +++- > > 4 files changed, 65 insertions(+), 8 deletions(-) > > > Shouldn't something be added to the nfs(5) man page > as well as blurb added to /etc/nfsmount.conf file? > Sure, but I'd like comments/consensus on the kernel bits first.
From: Trond Myklebust <trond.myklebust@hammerspace.com> The following patch series sets up a new mount option 'writes=lazy/eager/wait'. The mount option basically controls how the write() system call works. - writes=lazy is the default, and keeps the current behaviour - writes=eager means we send off the write immediately as an unstable write to the server. - writes=wait means we send off the write as an unstable write, and then wait for the reply. The main motivator for this behaviour is that some applications expect write() to return ENOSPC. Setting writes=wait should satisfy those applications without taking the full overhead of a synchronous write. writes=eager, on the other hand, can be useful for applications such as re-exporting NFS, since it would allow knfsd on the proxying server to immediately forward the writes to the original server. Trond Myklebust (3): NFS: 'flags' field should be unsigned in struct nfs_server NFS: Add support for eager writes NFS: Add mount options supporting eager writes fs/nfs/file.c | 19 +++++++++++++++++-- fs/nfs/fs_context.c | 33 +++++++++++++++++++++++++++++++++ fs/nfs/write.c | 17 ++++++++++++----- include/linux/nfs_fs_sb.h | 4 +++- 4 files changed, 65 insertions(+), 8 deletions(-)