| Message ID | 20201130212455.254469-3-trondmy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Patches to support NFS re-exporting | expand |
Makes sense to me, thanks.--b. On Mon, Nov 30, 2020 at 04:24:51PM -0500, trondmy@kernel.org wrote: > From: Jeff Layton <jeff.layton@primarydata.com> > > When we start allowing NFS to be reexported, then we have some problems > when it comes to subtree checking. In principle, we could allow it, but > it would mean encoding parent info in the filehandles and there may not > be enough space for that in a NFSv3 filehandle. > > To enforce this at export upcall time, we add a new export_ops flag > that declares the filesystem ineligible for subtree checking. > > Signed-off-by: Jeff Layton <jeff.layton@primarydata.com> > Signed-off-by: Lance Shelton <lance.shelton@hammerspace.com> > Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> > --- > Documentation/filesystems/nfs/exporting.rst | 14 +++++++++++++- > fs/nfs/export.c | 2 +- > fs/nfsd/export.c | 6 ++++++ > include/linux/exportfs.h | 1 + > 4 files changed, 21 insertions(+), 2 deletions(-) > > diff --git a/Documentation/filesystems/nfs/exporting.rst b/Documentation/filesystems/nfs/exporting.rst > index a3e3805833d1..960be64446cb 100644 > --- a/Documentation/filesystems/nfs/exporting.rst > +++ b/Documentation/filesystems/nfs/exporting.rst > @@ -176,7 +176,7 @@ contains a "flags" field that allows the filesystem to communicate to nfsd > that it may want to do things differently when dealing with it. The > following flags are defined: > > - EXPORT_OP_NOWCC > + EXPORT_OP_NOWCC - disable NFSv3 WCC attributes on this filesystem > RFC 1813 recommends that servers always send weak cache consistency > (WCC) data to the client after each operation. The server should > atomically collect attributes about the inode, do an operation on it, > @@ -190,3 +190,15 @@ following flags are defined: > this on filesystems that have an expensive ->getattr inode operation, > or when atomicity between pre and post operation attribute collection > is impossible to guarantee. > + > + EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs > + Many NFS operations deal with filehandles, which the server must then > + vet to ensure that they live inside of an exported tree. When the > + export consists of an entire filesystem, this is trivial. nfsd can just > + ensure that the filehandle live on the filesystem. When only part of a > + filesystem is exported however, then nfsd must walk the ancestors of the > + inode to ensure that it's within an exported subtree. This is an > + expensive operation and not all filesystems can support it properly. > + This flag exempts the filesystem from subtree checking and causes > + exportfs to get back an error if it tries to enable subtree checking > + on it. > diff --git a/fs/nfs/export.c b/fs/nfs/export.c > index 8f4c528865c5..b9ba306bf912 100644 > --- a/fs/nfs/export.c > +++ b/fs/nfs/export.c > @@ -171,5 +171,5 @@ const struct export_operations nfs_export_ops = { > .encode_fh = nfs_encode_fh, > .fh_to_dentry = nfs_fh_to_dentry, > .get_parent = nfs_get_parent, > - .flags = EXPORT_OP_NOWCC, > + .flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK, > }; > diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c > index 21e404e7cb68..81e7bb12aca6 100644 > --- a/fs/nfsd/export.c > +++ b/fs/nfsd/export.c > @@ -408,6 +408,12 @@ static int check_export(struct inode *inode, int *flags, unsigned char *uuid) > return -EINVAL; > } > > + if (inode->i_sb->s_export_op->flags & EXPORT_OP_NOSUBTREECHK && > + !(*flags & NFSEXP_NOSUBTREECHECK)) { > + dprintk("%s: %s does not support subtree checking!\n", > + __func__, inode->i_sb->s_type->name); > + return -EINVAL; > + } > return 0; > > } > diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h > index e7de0103a32e..2fcbab0f6b61 100644 > --- a/include/linux/exportfs.h > +++ b/include/linux/exportfs.h > @@ -214,6 +214,7 @@ struct export_operations { > int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, > int nr_iomaps, struct iattr *iattr); > #define EXPORT_OP_NOWCC (0x1) /* Don't collect wcc data for NFSv3 replies */ > +#define EXPORT_OP_NOSUBTREECHK (0x2) /* Subtree checking is not supported! */ > unsigned long flags; > }; > > -- > 2.28.0
diff --git a/Documentation/filesystems/nfs/exporting.rst b/Documentation/filesystems/nfs/exporting.rst index a3e3805833d1..960be64446cb 100644 --- a/Documentation/filesystems/nfs/exporting.rst +++ b/Documentation/filesystems/nfs/exporting.rst @@ -176,7 +176,7 @@ contains a "flags" field that allows the filesystem to communicate to nfsd that it may want to do things differently when dealing with it. The following flags are defined: - EXPORT_OP_NOWCC + EXPORT_OP_NOWCC - disable NFSv3 WCC attributes on this filesystem RFC 1813 recommends that servers always send weak cache consistency (WCC) data to the client after each operation. The server should atomically collect attributes about the inode, do an operation on it, @@ -190,3 +190,15 @@ following flags are defined: this on filesystems that have an expensive ->getattr inode operation, or when atomicity between pre and post operation attribute collection is impossible to guarantee. + + EXPORT_OP_NOSUBTREECHK - disallow subtree checking on this fs + Many NFS operations deal with filehandles, which the server must then + vet to ensure that they live inside of an exported tree. When the + export consists of an entire filesystem, this is trivial. nfsd can just + ensure that the filehandle live on the filesystem. When only part of a + filesystem is exported however, then nfsd must walk the ancestors of the + inode to ensure that it's within an exported subtree. This is an + expensive operation and not all filesystems can support it properly. + This flag exempts the filesystem from subtree checking and causes + exportfs to get back an error if it tries to enable subtree checking + on it. diff --git a/fs/nfs/export.c b/fs/nfs/export.c index 8f4c528865c5..b9ba306bf912 100644 --- a/fs/nfs/export.c +++ b/fs/nfs/export.c @@ -171,5 +171,5 @@ const struct export_operations nfs_export_ops = { .encode_fh = nfs_encode_fh, .fh_to_dentry = nfs_fh_to_dentry, .get_parent = nfs_get_parent, - .flags = EXPORT_OP_NOWCC, + .flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK, }; diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 21e404e7cb68..81e7bb12aca6 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -408,6 +408,12 @@ static int check_export(struct inode *inode, int *flags, unsigned char *uuid) return -EINVAL; } + if (inode->i_sb->s_export_op->flags & EXPORT_OP_NOSUBTREECHK && + !(*flags & NFSEXP_NOSUBTREECHECK)) { + dprintk("%s: %s does not support subtree checking!\n", + __func__, inode->i_sb->s_type->name); + return -EINVAL; + } return 0; } diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index e7de0103a32e..2fcbab0f6b61 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -214,6 +214,7 @@ struct export_operations { int (*commit_blocks)(struct inode *inode, struct iomap *iomaps, int nr_iomaps, struct iattr *iattr); #define EXPORT_OP_NOWCC (0x1) /* Don't collect wcc data for NFSv3 replies */ +#define EXPORT_OP_NOSUBTREECHK (0x2) /* Subtree checking is not supported! */ unsigned long flags; };