| Message ID | 20241201-work-exportfs-v1-1-b850dda4502a@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | exportfs: add flag to allow marking export operations as only supporting file handles | expand |
On Sun, Dec 1, 2024 at 2:13 PM Christian Brauner <brauner@kernel.org> wrote: > > Some filesystems like kernfs and pidfs support file handles as a > convenience to use name_to_handle_at(2) and open_by_handle_at(2) but > don't want to and cannot be reliably exported. Add a flag that allows > them to mark their export operations accordingly. > > Fixes: aa8188253474 ("kernfs: add exportfs operations") > Cc: stable <stable@kernel.org> # >= 4.14 > Signed-off-by: Christian Brauner <brauner@kernel.org> > --- > fs/nfsd/export.c | 8 +++++++- > include/linux/exportfs.h | 1 + > 2 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c > index eacafe46e3b673cb306bd3c7caabd3283a1e54b1..786551595cc1c2043e8c195c00ca72ef93c769d6 100644 > --- a/fs/nfsd/export.c > +++ b/fs/nfsd/export.c > @@ -417,6 +417,7 @@ static struct svc_export *svc_export_lookup(struct svc_export *); > static int check_export(struct path *path, int *flags, unsigned char *uuid) > { > struct inode *inode = d_inode(path->dentry); > + const struct export_operations *nop; > > /* > * We currently export only dirs, regular files, and (for v4 > @@ -449,11 +450,16 @@ static int check_export(struct path *path, int *flags, unsigned char *uuid) > return -EINVAL; > } > > - if (!exportfs_can_decode_fh(inode->i_sb->s_export_op)) { > + if (!exportfs_can_decode_fh(nop)) { > dprintk("exp_export: export of invalid fs type.\n"); > return -EINVAL; > } > > + if (nop && nop->flags & EXPORT_OP_LOCAL_FILE_HANDLE) { > + dprintk("exp_export: filesystem only supports non-exportable file handles.\n"); > + return -EINVAL; > + } > + > if (is_idmapped_mnt(path->mnt)) { > dprintk("exp_export: export of idmapped mounts not yet supported.\n"); > return -EINVAL; > diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h > index a087606ace194ccc9d1250f990ce55627aaf8dc5..40f78c8e4f31b97b2101b66634e8d1807c1bcc14 100644 > --- a/include/linux/exportfs.h > +++ b/include/linux/exportfs.h > @@ -280,6 +280,7 @@ struct export_operations { > */ > #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */ > #define EXPORT_OP_ASYNC_LOCK (0x40) /* fs can do async lock request */ > +#define EXPORT_OP_LOCAL_FILE_HANDLE (0x80) /* fs only supports file handles, no proper export */ > unsigned long flags; > }; Please update Documentation/filesystems/nfs/exporting.rst. Thanks, Amir.
On Sun, Dec 01, 2024 at 02:12:25PM +0100, Christian Brauner wrote: > Some filesystems like kernfs and pidfs support file handles as a > convenience to use name_to_handle_at(2) and open_by_handle_at(2) but > don't want to and cannot be reliably exported. Add a flag that allows > them to mark their export operations accordingly. > > Fixes: aa8188253474 ("kernfs: add exportfs operations") > Cc: stable <stable@kernel.org> # >= 4.14 > Signed-off-by: Christian Brauner <brauner@kernel.org> > --- > fs/nfsd/export.c | 8 +++++++- > include/linux/exportfs.h | 1 + > 2 files changed, 8 insertions(+), 1 deletion(-) > > diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c > index eacafe46e3b673cb306bd3c7caabd3283a1e54b1..786551595cc1c2043e8c195c00ca72ef93c769d6 100644 > --- a/fs/nfsd/export.c > +++ b/fs/nfsd/export.c > @@ -417,6 +417,7 @@ static struct svc_export *svc_export_lookup(struct svc_export *); > static int check_export(struct path *path, int *flags, unsigned char *uuid) > { > struct inode *inode = d_inode(path->dentry); > + const struct export_operations *nop; > > /* > * We currently export only dirs, regular files, and (for v4 > @@ -449,11 +450,16 @@ static int check_export(struct path *path, int *flags, unsigned char *uuid) > return -EINVAL; > } > > - if (!exportfs_can_decode_fh(inode->i_sb->s_export_op)) { > + if (!exportfs_can_decode_fh(nop)) { Where is nop initialised? > dprintk("exp_export: export of invalid fs type.\n"); > return -EINVAL; > } > > + if (nop && nop->flags & EXPORT_OP_LOCAL_FILE_HANDLE) { Also, please use () around & operations so we can understand that this is not an accidental typo. i.e: if (nop && (nop->flags & EXPORT_OP_LOCAL_FILE_HANDLE)) { clearly expresses the intent of the code, and now it is obviously correct at a glance. -Dave.
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index eacafe46e3b673cb306bd3c7caabd3283a1e54b1..786551595cc1c2043e8c195c00ca72ef93c769d6 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -417,6 +417,7 @@ static struct svc_export *svc_export_lookup(struct svc_export *); static int check_export(struct path *path, int *flags, unsigned char *uuid) { struct inode *inode = d_inode(path->dentry); + const struct export_operations *nop; /* * We currently export only dirs, regular files, and (for v4 @@ -449,11 +450,16 @@ static int check_export(struct path *path, int *flags, unsigned char *uuid) return -EINVAL; } - if (!exportfs_can_decode_fh(inode->i_sb->s_export_op)) { + if (!exportfs_can_decode_fh(nop)) { dprintk("exp_export: export of invalid fs type.\n"); return -EINVAL; } + if (nop && nop->flags & EXPORT_OP_LOCAL_FILE_HANDLE) { + dprintk("exp_export: filesystem only supports non-exportable file handles.\n"); + return -EINVAL; + } + if (is_idmapped_mnt(path->mnt)) { dprintk("exp_export: export of idmapped mounts not yet supported.\n"); return -EINVAL; diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index a087606ace194ccc9d1250f990ce55627aaf8dc5..40f78c8e4f31b97b2101b66634e8d1807c1bcc14 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -280,6 +280,7 @@ struct export_operations { */ #define EXPORT_OP_FLUSH_ON_CLOSE (0x20) /* fs flushes file data on close */ #define EXPORT_OP_ASYNC_LOCK (0x40) /* fs can do async lock request */ +#define EXPORT_OP_LOCAL_FILE_HANDLE (0x80) /* fs only supports file handles, no proper export */ unsigned long flags; };
Some filesystems like kernfs and pidfs support file handles as a convenience to use name_to_handle_at(2) and open_by_handle_at(2) but don't want to and cannot be reliably exported. Add a flag that allows them to mark their export operations accordingly. Fixes: aa8188253474 ("kernfs: add exportfs operations") Cc: stable <stable@kernel.org> # >= 4.14 Signed-off-by: Christian Brauner <brauner@kernel.org> --- fs/nfsd/export.c | 8 +++++++- include/linux/exportfs.h | 1 + 2 files changed, 8 insertions(+), 1 deletion(-)