So far, all callers of exportfs_encode_inode_fh(), except for fsnotify's
show_mark_fhandle(), check that filesystem can decode file handles, but
we would like to add more callers that do not require a file handle that
can be decoded.
Introduce a flag to explicitly request a file handle that may not to be
decoded later and a wrapper exportfs_encode_fid() that sets this flag
and convert show_mark_fhandle() to use the new wrapper.
This will be used to allow adding fanotify support to filesystems that
do not support NFS export.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
Documentation/filesystems/nfs/exporting.rst | 4 ++--
fs/exportfs/expfs.c | 18 ++++++++++++++++--
fs/notify/fanotify/fanotify.c | 4 ++--
fs/notify/fdinfo.c | 2 +-
include/linux/exportfs.h | 12 +++++++++++-
5 files changed, 32 insertions(+), 8 deletions(-)
diff --git a/Documentation/filesystems/nfs/exporting.rst b/Documentation/filesystems/nfs/exporting.rst
index 0e98edd353b5..3d97b8d8f735 100644
--- a/Documentation/filesystems/nfs/exporting.rst
+++ b/Documentation/filesystems/nfs/exporting.rst
@@ -122,8 +122,8 @@ are exportable by setting the s_export_op field in the struct
super_block. This field must point to a "struct export_operations"
struct which has the following members:
- encode_fh (optional)
- Takes a dentry and creates a filehandle fragment which can later be used
+ encode_fh (optional)
+ Takes a dentry and creates a filehandle fragment which may later be used
to find or create a dentry for the same object. The default
implementation creates a filehandle fragment that encodes a 32bit inode
and generation number for the inode encoded, and if necessary the
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index bf1b4925fedd..1b35dda5bdda 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -381,11 +381,25 @@ static int export_encode_fh(struct inode *inode, struct fid *fid,
return type;
}
+/**
+ * exportfs_encode_inode_fh - encode a file handle from inode
+ * @inode: the object to encode
+ * @fid: where to store the file handle fragment
+ * @max_len: maximum length to store there
+ * @flags: properties of the requrested file handle
+ */
int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
- int *max_len, struct inode *parent)
+ int *max_len, struct inode *parent, int flags)
{
const struct export_operations *nop = inode->i_sb->s_export_op;
+ /*
+ * If a decodeable file handle was requested, we need to make sure that
+ * filesystem can decode file handles.
+ */
+ if (nop && !(flags & EXPORT_FH_FID) && !nop->fh_to_dentry)
+ return -EOPNOTSUPP;
+
if (nop && nop->encode_fh)
return nop->encode_fh(inode, fid->raw, max_len, parent);
@@ -416,7 +430,7 @@ int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
parent = p->d_inode;
}
- error = exportfs_encode_inode_fh(inode, fid, max_len, parent);
+ error = exportfs_encode_inode_fh(inode, fid, max_len, parent, flags);
dput(p);
return error;
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 29bdd99b29fa..d1a49f5b6e6d 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -380,7 +380,7 @@ static int fanotify_encode_fh_len(struct inode *inode)
if (!inode)
return 0;
- exportfs_encode_inode_fh(inode, NULL, &dwords, NULL);
+ exportfs_encode_inode_fh(inode, NULL, &dwords, NULL, 0);
fh_len = dwords << 2;
/*
@@ -443,7 +443,7 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
}
dwords = fh_len >> 2;
- type = exportfs_encode_inode_fh(inode, buf, &dwords, NULL);
+ type = exportfs_encode_inode_fh(inode, buf, &dwords, NULL, 0);
err = -EINVAL;
if (!type || type == FILEID_INVALID || fh_len != dwords << 2)
goto out_err;
diff --git a/fs/notify/fdinfo.c b/fs/notify/fdinfo.c
index 55081ae3a6ec..5c430736ec12 100644
--- a/fs/notify/fdinfo.c
+++ b/fs/notify/fdinfo.c
@@ -50,7 +50,7 @@ static void show_mark_fhandle(struct seq_file *m, struct inode *inode)
f.handle.handle_bytes = sizeof(f.pad);
size = f.handle.handle_bytes >> 2;
- ret = exportfs_encode_inode_fh(inode, (struct fid *)f.handle.f_handle, &size, NULL);
+ ret = exportfs_encode_fid(inode, (struct fid *)f.handle.f_handle, &size);
if ((ret == FILEID_INVALID) || (ret < 0)) {
WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret);
return;
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index 2b1048238170..635e89e1dae7 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -136,6 +136,7 @@ struct fid {
};
#define EXPORT_FH_CONNECTABLE 0x1
+#define EXPORT_FH_FID 0x2
/**
* struct export_operations - for nfsd to communicate with file systems
@@ -226,9 +227,18 @@ struct export_operations {
};
extern int exportfs_encode_inode_fh(struct inode *inode, struct fid *fid,
- int *max_len, struct inode *parent);
+ int *max_len, struct inode *parent,
+ int flags);
extern int exportfs_encode_fh(struct dentry *dentry, struct fid *fid,
int *max_len, int flags);
+
+static inline int exportfs_encode_fid(struct inode *inode, struct fid *fid,
+ int *max_len)
+{
+ return exportfs_encode_inode_fh(inode, fid, max_len, NULL,
+ EXPORT_FH_FID);
+}
+
extern struct dentry *exportfs_decode_fh_raw(struct vfsmount *mnt,
struct fid *fid, int fh_len,
int fileid_type,
--
2.34.1
