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authorChristoph Hellwig <hch@lst.de>2007-10-21 16:42:05 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-22 08:13:19 -0700
commit2596110a3994593f6aa3e2bb76345ad4791b1a14 (patch)
tree0f1773238265f83e1b5640256176851a60ff5ea8 /fs/exportfs
parent6e91ea2bb0b6a3ddf6d4faeb54a9c20d4e20bc42 (diff)
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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>
Diffstat (limited to 'fs/exportfs')
-rw-r--r--fs/exportfs/expfs.c136
1 files changed, 130 insertions, 6 deletions
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 813011aad700..99294a23cd54 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -514,17 +514,141 @@ struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
int (*acceptable)(void *, struct dentry *), void *context)
{
struct export_operations *nop = mnt->mnt_sb->s_export_op;
- struct dentry *result;
+ struct dentry *result, *alias;
+ int err;
- if (nop->decode_fh) {
- result = nop->decode_fh(mnt->mnt_sb, fid->raw, fh_len,
+ /*
+ * Old way of doing things. Will go away soon.
+ */
+ if (!nop->fh_to_dentry) {
+ if (nop->decode_fh) {
+ return nop->decode_fh(mnt->mnt_sb, fid->raw, fh_len,
fileid_type, acceptable, context);
+ } else {
+ return export_decode_fh(mnt->mnt_sb, fid->raw, fh_len,
+ fileid_type, acceptable, context);
+ }
+ }
+
+ /*
+ * Try to get any dentry for the given file handle from the filesystem.
+ */
+ result = nop->fh_to_dentry(mnt->mnt_sb, fid, fh_len, fileid_type);
+ if (!result)
+ result = ERR_PTR(-ESTALE);
+ if (IS_ERR(result))
+ return result;
+
+ if (S_ISDIR(result->d_inode->i_mode)) {
+ /*
+ * This request is for a directory.
+ *
+ * On the positive side there is only one dentry for each
+ * directory inode. On the negative side this implies that we
+ * to ensure our dentry is connected all the way up to the
+ * filesystem root.
+ */
+ if (result->d_flags & DCACHE_DISCONNECTED) {
+ err = reconnect_path(mnt->mnt_sb, result);
+ if (err)
+ goto err_result;
+ }
+
+ if (!acceptable(context, result)) {
+ err = -EACCES;
+ goto err_result;
+ }
+
+ return result;
} else {
- result = export_decode_fh(mnt->mnt_sb, fid->raw, fh_len,
- fileid_type, acceptable, context);
+ /*
+ * It's not a directory. Life is a little more complicated.
+ */
+ struct dentry *target_dir, *nresult;
+ char nbuf[NAME_MAX+1];
+
+ /*
+ * See if either the dentry we just got from the filesystem
+ * or any alias for it is acceptable. This is always true
+ * if this filesystem is exported without the subtreecheck
+ * option. If the filesystem is exported with the subtree
+ * check option there's a fair chance we need to look at
+ * the parent directory in the file handle and make sure
+ * it's connected to the filesystem root.
+ */
+ alias = find_acceptable_alias(result, acceptable, context);
+ if (alias)
+ return alias;
+
+ /*
+ * Try to extract a dentry for the parent directory from the
+ * file handle. If this fails we'll have to give up.
+ */
+ err = -ESTALE;
+ if (!nop->fh_to_parent)
+ goto err_result;
+
+ target_dir = nop->fh_to_parent(mnt->mnt_sb, fid,
+ fh_len, fileid_type);
+ if (!target_dir)
+ goto err_result;
+ err = PTR_ERR(target_dir);
+ if (IS_ERR(target_dir))
+ goto err_result;
+
+ /*
+ * And as usual we need to make sure the parent directory is
+ * connected to the filesystem root. The VFS really doesn't
+ * like disconnected directories..
+ */
+ err = reconnect_path(mnt->mnt_sb, target_dir);
+ if (err) {
+ dput(target_dir);
+ goto err_result;
+ }
+
+ /*
+ * Now that we've got both a well-connected parent and a
+ * dentry for the inode we're after, make sure that our
+ * inode is actually connected to the parent.
+ */
+ err = exportfs_get_name(target_dir, nbuf, result);
+ if (!err) {
+ mutex_lock(&target_dir->d_inode->i_mutex);
+ nresult = lookup_one_len(nbuf, target_dir,
+ strlen(nbuf));
+ mutex_unlock(&target_dir->d_inode->i_mutex);
+ if (!IS_ERR(nresult)) {
+ if (nresult->d_inode) {
+ dput(result);
+ result = nresult;
+ } else
+ dput(nresult);
+ }
+ }
+
+ /*
+ * At this point we are done with the parent, but it's pinned
+ * by the child dentry anyway.
+ */
+ dput(target_dir);
+
+ /*
+ * And finally make sure the dentry is actually acceptable
+ * to NFSD.
+ */
+ alias = find_acceptable_alias(result, acceptable, context);
+ if (!alias) {
+ err = -EACCES;
+ goto err_result;
+ }
+
+ return alias;
}
- return result;
+ err_result:
+ dput(result);
+ return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(exportfs_decode_fh);