exportfs: add new methods
Add the guts for the new filesystem API to exportfs.
There's now a fh_to_dentry method that returns a dentry for the object looked
for given a filehandle fragment, and a fh_to_parent operation that returns the
dentry for the encoded parent directory in case the file handle contains it.
There are default implementations for these methods that only take a callback
for an nfs-enhanced iget variant and implement the rest of the semantics.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: <linux-ext4@vger.kernel.org>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Anton Altaparmakov <aia21@cantab.net>
Cc: David Chinner <dgc@sgi.com>
Cc: Timothy Shimmin <tes@sgi.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Chris Mason <mason@suse.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/libfs.c b/fs/libfs.c
index ae51481..6e68b70 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -8,6 +8,7 @@
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/mutex.h>
+#include <linux/exportfs.h>
#include <asm/uaccess.h>
@@ -678,6 +679,93 @@
return ret;
}
+/*
+ * This is what d_alloc_anon should have been. Once the exportfs
+ * argument transition has been finished I will update d_alloc_anon
+ * to this prototype and this wrapper will go away. --hch
+ */
+static struct dentry *exportfs_d_alloc(struct inode *inode)
+{
+ struct dentry *dentry;
+
+ if (!inode)
+ return NULL;
+ if (IS_ERR(inode))
+ return ERR_PTR(PTR_ERR(inode));
+
+ dentry = d_alloc_anon(inode);
+ if (!dentry) {
+ iput(inode);
+ dentry = ERR_PTR(-ENOMEM);
+ }
+ return dentry;
+}
+
+/**
+ * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
+ * @sb: filesystem to do the file handle conversion on
+ * @fid: file handle to convert
+ * @fh_len: length of the file handle in bytes
+ * @fh_type: type of file handle
+ * @get_inode: filesystem callback to retrieve inode
+ *
+ * This function decodes @fid as long as it has one of the well-known
+ * Linux filehandle types and calls @get_inode on it to retrieve the
+ * inode for the object specified in the file handle.
+ */
+struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type, struct inode *(*get_inode)
+ (struct super_block *sb, u64 ino, u32 gen))
+{
+ struct inode *inode = NULL;
+
+ if (fh_len < 2)
+ return NULL;
+
+ switch (fh_type) {
+ case FILEID_INO32_GEN:
+ case FILEID_INO32_GEN_PARENT:
+ inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
+ break;
+ }
+
+ return exportfs_d_alloc(inode);
+}
+EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
+
+/**
+ * generic_fh_to_dentry - generic helper for the fh_to_parent export operation
+ * @sb: filesystem to do the file handle conversion on
+ * @fid: file handle to convert
+ * @fh_len: length of the file handle in bytes
+ * @fh_type: type of file handle
+ * @get_inode: filesystem callback to retrieve inode
+ *
+ * This function decodes @fid as long as it has one of the well-known
+ * Linux filehandle types and calls @get_inode on it to retrieve the
+ * inode for the _parent_ object specified in the file handle if it
+ * is specified in the file handle, or NULL otherwise.
+ */
+struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type, struct inode *(*get_inode)
+ (struct super_block *sb, u64 ino, u32 gen))
+{
+ struct inode *inode = NULL;
+
+ if (fh_len <= 2)
+ return NULL;
+
+ switch (fh_type) {
+ case FILEID_INO32_GEN_PARENT:
+ inode = get_inode(sb, fid->i32.parent_ino,
+ (fh_len > 3 ? fid->i32.parent_gen : 0));
+ break;
+ }
+
+ return exportfs_d_alloc(inode);
+}
+EXPORT_SYMBOL_GPL(generic_fh_to_parent);
+
EXPORT_SYMBOL(dcache_dir_close);
EXPORT_SYMBOL(dcache_dir_lseek);
EXPORT_SYMBOL(dcache_dir_open);
