1 files changed, 157 insertions, 203 deletions

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 8adb32a9387a..109ab5e44eca 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -1,4 +1,13 @@
-
+/*
+ * Copyright (C) Neil Brown 2002
+ * Copyright (C) Christoph Hellwig 2007
+ *
+ * This file contains the code mapping from inodes to NFS file handles,
+ * and for mapping back from file handles to dentries.
+ *
+ * For details on why we do all the strange and hairy things in here
+ * take a look at Documentation/filesystems/Exporting.
+ */
 #include <linux/exportfs.h>
 #include <linux/fs.h>
 #include <linux/file.h>
@@ -9,32 +18,19 @@
 #define dprintk(fmt, args...) do{}while(0)
 
 
-static int get_name(struct dentry *dentry, char *name,
+static int get_name(struct vfsmount *mnt, struct dentry *dentry, char *name,
                 struct dentry *child);
 
 
-static struct dentry *exportfs_get_dentry(struct super_block *sb, void *obj)
+static int exportfs_get_name(struct vfsmount *mnt, struct dentry *dir,
+                char *name, struct dentry *child)
 {
-        struct dentry *result = ERR_PTR(-ESTALE);
-
-        if (sb->s_export_op->get_dentry) {
-                result = sb->s_export_op->get_dentry(sb, obj);
-                if (!result)
-                        result = ERR_PTR(-ESTALE);
-        }
-
-        return result;
-}
-
-static int exportfs_get_name(struct dentry *dir, char *name,
-                struct dentry *child)
-{
-        struct export_operations *nop = dir->d_sb->s_export_op;
+        const struct export_operations *nop = dir->d_sb->s_export_op;
 
         if (nop->get_name)
                 return nop->get_name(dir, name, child);
         else
-                return get_name(dir, name, child);
+                return get_name(mnt, dir, name, child);
 }
 
 /*
@@ -98,7 +94,7 @@ find_disconnected_root(struct dentry *dentry)
  * It may already be, as the flag isn't always updated when connection happens.
  */
 static int
-reconnect_path(struct super_block *sb, struct dentry *target_dir)
+reconnect_path(struct vfsmount *mnt, struct dentry *target_dir)
 {
         char nbuf[NAME_MAX+1];
         int noprogress = 0;
@@ -121,7 +117,7 @@ reconnect_path(struct super_block *sb, struct dentry *target_dir)
                         pd->d_flags &= ~DCACHE_DISCONNECTED;
                         spin_unlock(&pd->d_lock);
                         noprogress = 0;
-                } else if (pd == sb->s_root) {
+                } else if (pd == mnt->mnt_sb->s_root) {
                         printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n");
                         spin_lock(&pd->d_lock);
                         pd->d_flags &= ~DCACHE_DISCONNECTED;
@@ -147,8 +143,8 @@ reconnect_path(struct super_block *sb, struct dentry *target_dir)
                         struct dentry *npd;
 
                         mutex_lock(&pd->d_inode->i_mutex);
-                        if (sb->s_export_op->get_parent)
-                                ppd = sb->s_export_op->get_parent(pd);
+                        if (mnt->mnt_sb->s_export_op->get_parent)
+                                ppd = mnt->mnt_sb->s_export_op->get_parent(pd);
                         mutex_unlock(&pd->d_inode->i_mutex);
 
                         if (IS_ERR(ppd)) {
@@ -161,7 +157,7 @@ reconnect_path(struct super_block *sb, struct dentry *target_dir)
 
                         dprintk("%s: find name of %lu in %lu\n", __FUNCTION__,
                                 pd->d_inode->i_ino, ppd->d_inode->i_ino);
-                        err = exportfs_get_name(ppd, nbuf, pd);
+                        err = exportfs_get_name(mnt, ppd, nbuf, pd);
                         if (err) {
                                 dput(ppd);
                                 dput(pd);
@@ -214,125 +210,6 @@ reconnect_path(struct super_block *sb, struct dentry *target_dir)
         return 0;
 }
 
-/**
- * find_exported_dentry - helper routine to implement export_operations->decode_fh
- * @sb:         The &super_block identifying the filesystem
- * @obj:        An opaque identifier of the object to be found - passed to
- *              get_inode
- * @parent:     An optional opqaue identifier of the parent of the object.
- * @acceptable: A function used to test possible &dentries to see if they are
- *              acceptable
- * @context:    A parameter to @acceptable so that it knows on what basis to
- *              judge.
- *
- * find_exported_dentry is the central helper routine to enable file systems
- * to provide the decode_fh() export_operation.  It's main task is to take
- * an &inode, find or create an appropriate &dentry structure, and possibly
- * splice this into the dcache in the correct place.
- *
- * The decode_fh() operation provided by the filesystem should call
- * find_exported_dentry() with the same parameters that it received except
- * that instead of the file handle fragment, pointers to opaque identifiers
- * for the object and optionally its parent are passed.  The default decode_fh
- * routine passes one pointer to the start of the filehandle fragment, and
- * one 8 bytes into the fragment.  It is expected that most filesystems will
- * take this approach, though the offset to the parent identifier may well be
- * different.
- *
- * find_exported_dentry() will call get_dentry to get an dentry pointer from
- * the file system.  If any &dentry in the d_alias list is acceptable, it will
- * be returned.  Otherwise find_exported_dentry() will attempt to splice a new
- * &dentry into the dcache using get_name() and get_parent() to find the
- * appropriate place.
- */
-
-struct dentry *
-find_exported_dentry(struct super_block *sb, void *obj, void *parent,
-                     int (*acceptable)(void *context, struct dentry *de),
-                     void *context)
-{
-        struct dentry *result, *alias;
-        int err = -ESTALE;
-
-        /*
-         * Attempt to find the inode.
-         */
-        result = exportfs_get_dentry(sb, obj);
-        if (IS_ERR(result))
-                return result;
-
-        if (S_ISDIR(result->d_inode->i_mode)) {
-                if (!(result->d_flags & DCACHE_DISCONNECTED)) {
-                        if (acceptable(context, result))
-                                return result;
-                        err = -EACCES;
-                        goto err_result;
-                }
-
-                err = reconnect_path(sb, result);
-                if (err)
-                        goto err_result;
-        } else {
-                struct dentry *target_dir, *nresult;
-                char nbuf[NAME_MAX+1];
-
-                alias = find_acceptable_alias(result, acceptable, context);
-                if (alias)
-                        return alias;
-
-                if (parent == NULL)
-                        goto err_result;
-
-                target_dir = exportfs_get_dentry(sb,parent);
-                if (IS_ERR(target_dir)) {
-                        err = PTR_ERR(target_dir);
-                        goto err_result;
-                }
-
-                err = reconnect_path(sb, target_dir);
-                if (err) {
-                        dput(target_dir);
-                        goto err_result;
-                }
-
-                /*
-                 * As we weren't after a directory, have one more step to go.
-                 */
-                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);
-                        }
-                }
-                dput(target_dir);
-        }
-
-        alias = find_acceptable_alias(result, acceptable, context);
-        if (alias)
-                return alias;
-
-        /* drat - I just cannot find anything acceptable */
-        dput(result);
-        /* It might be justifiable to return ESTALE here,
-         * but the filehandle at-least looks reasonable good
-         * and it may just be a permission problem, so returning
-         * -EACCESS is safer
-         */
-        return ERR_PTR(-EACCES);
-
- err_result:
-        dput(result);
-        return ERR_PTR(err);
-}
-
 struct getdents_callback {
         char *name;             /* name that was found. It already points to a
                                    buffer NAME_MAX+1 is size */
@@ -370,8 +247,8 @@ static int filldir_one(void * __buf, const char * name, int len,
  * calls readdir on the parent until it finds an entry with
  * the same inode number as the child, and returns that.
  */
-static int get_name(struct dentry *dentry, char *name,
-                        struct dentry *child)
+static int get_name(struct vfsmount *mnt, struct dentry *dentry,
+                char *name, struct dentry *child)
 {
         struct inode *dir = dentry->d_inode;
         int error;
@@ -387,7 +264,7 @@ static int get_name(struct dentry *dentry, char *name,
         /*
          * Open the directory ...
          */
-        file = dentry_open(dget(dentry), NULL, O_RDONLY);
+        file = dentry_open(dget(dentry), mntget(mnt), O_RDONLY);
         error = PTR_ERR(file);
         if (IS_ERR(file))
                 goto out;
@@ -434,100 +311,177 @@ out:
  * can be used to check that it is still valid.  It places them in the
  * filehandle fragment where export_decode_fh expects to find them.
  */
-static int export_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
-                   int connectable)
+static int export_encode_fh(struct dentry *dentry, struct fid *fid,
+                int *max_len, int connectable)
 {
         struct inode * inode = dentry->d_inode;
         int len = *max_len;
-        int type = 1;
+        int type = FILEID_INO32_GEN;
         
         if (len < 2 || (connectable && len < 4))
                 return 255;
 
         len = 2;
-        fh[0] = inode->i_ino;
-        fh[1] = inode->i_generation;
+        fid->i32.ino = inode->i_ino;
+        fid->i32.gen = inode->i_generation;
         if (connectable && !S_ISDIR(inode->i_mode)) {
                 struct inode *parent;
 
                 spin_lock(&dentry->d_lock);
                 parent = dentry->d_parent->d_inode;
-                fh[2] = parent->i_ino;
-                fh[3] = parent->i_generation;
+                fid->i32.parent_ino = parent->i_ino;
+                fid->i32.parent_gen = parent->i_generation;
                 spin_unlock(&dentry->d_lock);
                 len = 4;
-                type = 2;
+                type = FILEID_INO32_GEN_PARENT;
         }
         *max_len = len;
         return type;
 }
 
-
-/**
- * export_decode_fh - default export_operations->decode_fh function
- * @sb:  The superblock
- * @fh:  pointer to the file handle fragment
- * @fh_len: length of file handle fragment
- * @acceptable: function for testing acceptability of dentrys
- * @context:   context for @acceptable
- *
- * This is the default decode_fh() function.
- * a fileid_type of 1 indicates that the filehandlefragment
- * just contains an object identifier understood by  get_dentry.
- * a fileid_type of 2 says that there is also a directory
- * identifier 8 bytes in to the filehandlefragement.
- */
-static struct dentry *export_decode_fh(struct super_block *sb, __u32 *fh, int fh_len,
-                              int fileid_type,
-                         int (*acceptable)(void *context, struct dentry *de),
-                         void *context)
-{
-        __u32 parent[2];
-        parent[0] = parent[1] = 0;
-        if (fh_len < 2 || fileid_type > 2)
-                return NULL;
-        if (fileid_type == 2) {
-                if (fh_len > 2) parent[0] = fh[2];
-                if (fh_len > 3) parent[1] = fh[3];
-        }
-        return find_exported_dentry(sb, fh, parent,
-                                   acceptable, context);
-}
-
-int exportfs_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
+int exportfs_encode_fh(struct dentry *dentry, struct fid *fid, int *max_len,
                 int connectable)
 {
-        struct export_operations *nop = dentry->d_sb->s_export_op;
+        const struct export_operations *nop = dentry->d_sb->s_export_op;
         int error;
 
         if (nop->encode_fh)
-                error = nop->encode_fh(dentry, fh, max_len, connectable);
+                error = nop->encode_fh(dentry, fid->raw, max_len, connectable);
         else
-                error = export_encode_fh(dentry, fh, max_len, connectable);
+                error = export_encode_fh(dentry, fid, max_len, connectable);
 
         return error;
 }
 EXPORT_SYMBOL_GPL(exportfs_encode_fh);
 
-struct dentry *exportfs_decode_fh(struct vfsmount *mnt, __u32 *fh, int fh_len,
-                int fileid_type, int (*acceptable)(void *, struct dentry *),
-                void *context)
+struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
+                int fh_len, int fileid_type,
+                int (*acceptable)(void *, struct dentry *), void *context)
 {
-        struct export_operations *nop = mnt->mnt_sb->s_export_op;
-        struct dentry *result;
+        const struct export_operations *nop = mnt->mnt_sb->s_export_op;
+        struct dentry *result, *alias;
+        int err;
 
-        if (nop->decode_fh) {
-                result = nop->decode_fh(mnt->mnt_sb, fh, 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, 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, fh, 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, 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(mnt, 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);
 
-EXPORT_SYMBOL(find_exported_dentry);
-
 MODULE_LICENSE("GPL");