No, I've only used this for local testing so far. Perhaps you can
handhold me through adding such a patch to teuthology for it?
Note that this _really_ slows down I/O, especially if you're doing a lot
of small reads or writes, so it may not be appropriate for throughput-
heavy testing.
On Thu, 2022-01-06 at 05:41 -0800, Gregory Farnum wrote:
> This seems fine to me. Do you have a teuthology fragment to exercise this?
>
> Acked-by: Greg Farnum <gfarnum@xxxxxxxxxx>
>
> On Wed, Jan 5, 2022 at 5:27 AM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> >
> > CephFS is a bit unlike most other filesystems in that it only
> > conditionally does buffered I/O based on the caps that it gets from the
> > MDS. In most cases, unless there is contended access for an inode the
> > MDS does give Fbc caps to the client, so the unbuffered codepaths are
> > only infrequently traveled and are difficult to test.
> >
> > At one time, the "-o sync" mount option would give you this behavior,
> > but that was removed in commit 7ab9b3807097 ("ceph: Don't use
> > ceph-sync-mode for synchronous-fs.").
> >
> > Add a new mount option to tell the client to ignore Fbc caps when doing
> > I/O, and to use the synchronous codepaths exclusively, even on
> > non-O_DIRECT file descriptors. We already have an ioctl that forces this
> > behavior on a per-inode basis, so we can just always set the CEPH_F_SYNC
> > flag on such mounts.
> >
> > Additionally, this patch also changes the client to not request Fbc when
> > doing direct I/O. We aren't using the cache with O_DIRECT so we don't
> > have any need for those caps.
> >
> > Cc: majianpeng <majianpeng@xxxxxxxxx>
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> > fs/ceph/file.c | 24 +++++++++++++++---------
> > fs/ceph/super.c | 11 +++++++++++
> > fs/ceph/super.h | 1 +
> > 3 files changed, 27 insertions(+), 9 deletions(-)
> >
> > I've been working with this patch in order to test the synchronous
> > codepaths for content encryption. I think though that this might make
> > sense to take into mainline, as it could be helpful for troubleshooting,
> > and ensuring that these codepaths are regularly tested.
> >
> > Either way, I think the cap handling changes probably make sense on
> > their own. I can split that out if we don't want to take the mount
> > option in as well.
> >
> > Thoughts?
> >
> > diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> > index c138e8126286..7de5db51c3d0 100644
> > --- a/fs/ceph/file.c
> > +++ b/fs/ceph/file.c
> > @@ -204,6 +204,8 @@ static int ceph_init_file_info(struct inode *inode, struct file *file,
> > int fmode, bool isdir)
> > {
> > struct ceph_inode_info *ci = ceph_inode(inode);
> > + struct ceph_mount_options *opt =
> > + ceph_inode_to_client(&ci->vfs_inode)->mount_options;
> > struct ceph_file_info *fi;
> >
> > dout("%s %p %p 0%o (%s)\n", __func__, inode, file,
> > @@ -225,6 +227,9 @@ static int ceph_init_file_info(struct inode *inode, struct file *file,
> > if (!fi)
> > return -ENOMEM;
> >
> > + if (opt->flags & CEPH_MOUNT_OPT_NOPAGECACHE)
> > + fi->flags |= CEPH_F_SYNC;
> > +
> > file->private_data = fi;
> > }
> >
> > @@ -1536,7 +1541,7 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
> > struct ceph_inode_info *ci = ceph_inode(inode);
> > bool direct_lock = iocb->ki_flags & IOCB_DIRECT;
> > ssize_t ret;
> > - int want, got = 0;
> > + int want = 0, got = 0;
> > int retry_op = 0, read = 0;
> >
> > again:
> > @@ -1551,13 +1556,14 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
> > else
> > ceph_start_io_read(inode);
> >
> > + if (!(fi->flags & CEPH_F_SYNC) && !direct_lock)
> > + want |= CEPH_CAP_FILE_CACHE;
> > if (fi->fmode & CEPH_FILE_MODE_LAZY)
> > - want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
> > - else
> > - want = CEPH_CAP_FILE_CACHE;
> > + want |= CEPH_CAP_FILE_LAZYIO;
> > +
> > ret = ceph_get_caps(filp, CEPH_CAP_FILE_RD, want, -1, &got);
> > if (ret < 0) {
> > - if (iocb->ki_flags & IOCB_DIRECT)
> > + if (direct_lock)
> > ceph_end_io_direct(inode);
> > else
> > ceph_end_io_read(inode);
> > @@ -1691,7 +1697,7 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
> > struct ceph_osd_client *osdc = &fsc->client->osdc;
> > struct ceph_cap_flush *prealloc_cf;
> > ssize_t count, written = 0;
> > - int err, want, got;
> > + int err, want = 0, got;
> > bool direct_lock = false;
> > u32 map_flags;
> > u64 pool_flags;
> > @@ -1766,10 +1772,10 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
> >
> > dout("aio_write %p %llx.%llx %llu~%zd getting caps. i_size %llu\n",
> > inode, ceph_vinop(inode), pos, count, i_size_read(inode));
> > + if (!(fi->flags & CEPH_F_SYNC) && !direct_lock)
> > + want |= CEPH_CAP_FILE_BUFFER;
> > if (fi->fmode & CEPH_FILE_MODE_LAZY)
> > - want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
> > - else
> > - want = CEPH_CAP_FILE_BUFFER;
> > + want |= CEPH_CAP_FILE_LAZYIO;
> > got = 0;
> > err = ceph_get_caps(file, CEPH_CAP_FILE_WR, want, pos + count, &got);
> > if (err < 0)
> > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > index 8d6daea351f6..d7e604a56fd9 100644
> > --- a/fs/ceph/super.c
> > +++ b/fs/ceph/super.c
> > @@ -160,6 +160,7 @@ enum {
> > Opt_quotadf,
> > Opt_copyfrom,
> > Opt_wsync,
> > + Opt_pagecache,
> > };
> >
> > enum ceph_recover_session_mode {
> > @@ -201,6 +202,7 @@ static const struct fs_parameter_spec ceph_mount_parameters[] = {
> > fsparam_string ("mon_addr", Opt_mon_addr),
> > fsparam_u32 ("wsize", Opt_wsize),
> > fsparam_flag_no ("wsync", Opt_wsync),
> > + fsparam_flag_no ("pagecache", Opt_pagecache),
> > {}
> > };
> >
> > @@ -567,6 +569,12 @@ static int ceph_parse_mount_param(struct fs_context *fc,
> > else
> > fsopt->flags |= CEPH_MOUNT_OPT_ASYNC_DIROPS;
> > break;
> > + case Opt_pagecache:
> > + if (result.negated)
> > + fsopt->flags |= CEPH_MOUNT_OPT_NOPAGECACHE;
> > + else
> > + fsopt->flags &= ~CEPH_MOUNT_OPT_NOPAGECACHE;
> > + break;
> > default:
> > BUG();
> > }
> > @@ -702,6 +710,9 @@ static int ceph_show_options(struct seq_file *m, struct dentry *root)
> > if (!(fsopt->flags & CEPH_MOUNT_OPT_ASYNC_DIROPS))
> > seq_puts(m, ",wsync");
> >
> > + if (fsopt->flags & CEPH_MOUNT_OPT_NOPAGECACHE)
> > + seq_puts(m, ",nopagecache");
> > +
> > if (fsopt->wsize != CEPH_MAX_WRITE_SIZE)
> > seq_printf(m, ",wsize=%u", fsopt->wsize);
> > if (fsopt->rsize != CEPH_MAX_READ_SIZE)
> > diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> > index f9b1bbf26c1b..5c6d9384b7be 100644
> > --- a/fs/ceph/super.h
> > +++ b/fs/ceph/super.h
> > @@ -46,6 +46,7 @@
> > #define CEPH_MOUNT_OPT_NOQUOTADF (1<<13) /* no root dir quota in statfs */
> > #define CEPH_MOUNT_OPT_NOCOPYFROM (1<<14) /* don't use RADOS 'copy-from' op */
> > #define CEPH_MOUNT_OPT_ASYNC_DIROPS (1<<15) /* allow async directory ops */
> > +#define CEPH_MOUNT_OPT_NOPAGECACHE (1<<16) /* bypass pagecache altogether */
> >
> > #define CEPH_MOUNT_OPT_DEFAULT \
> > (CEPH_MOUNT_OPT_DCACHE | \
> > --
> > 2.33.1
> >
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
