udf: Make udf exportable

Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Rasmus Rohde <rohde@duff.dk>
Signed-off-by: Jan Kara <jack@suse.cz>

4 files changed, 161 insertions, 2 deletions

diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index ba5537d4bc15..47a6589e10b5 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -32,6 +32,7 @@
 #include <linux/buffer_head.h>
 #include <linux/sched.h>
 #include <linux/crc-itu-t.h>
+#include <linux/exportfs.h>
 
 static inline int udf_match(int len1, const char *name1, int len2,
                             const char *name2)
@@ -158,6 +159,8 @@ static struct fileIdentDesc *udf_find_entry(struct inode *dir,
         sector_t offset;
         struct extent_position epos = {};
         struct udf_inode_info *dinfo = UDF_I(dir);
+        int isdotdot = dentry->d_name.len == 2 &&
+                dentry->d_name.name[0] == '.' && dentry->d_name.name[1] == '.';
 
         size = udf_ext0_offset(dir) + dir->i_size;
         f_pos = udf_ext0_offset(dir);
@@ -225,6 +228,12 @@ static struct fileIdentDesc *udf_find_entry(struct inode *dir,
                                 continue;
                 }
 
+                if ((cfi->fileCharacteristics & FID_FILE_CHAR_PARENT) &&
+                    isdotdot) {
+                        brelse(epos.bh);
+                        return fi;
+                }
+
                 if (!lfi)
                         continue;
 
@@ -286,9 +295,8 @@ static struct dentry *udf_lookup(struct inode *dir, struct dentry *dentry,
                 }
         }
         unlock_kernel();
-        d_add(dentry, inode);
 
-        return NULL;
+        return d_splice_alias(inode, dentry);
 }
 
 static struct fileIdentDesc *udf_add_entry(struct inode *dir,
@@ -1232,6 +1240,134 @@ end_rename:
         return retval;
 }
 
+static struct dentry *udf_get_parent(struct dentry *child)
+{
+        struct dentry *parent;
+        struct inode *inode = NULL;
+        struct dentry dotdot;
+        struct fileIdentDesc cfi;
+        struct udf_fileident_bh fibh;
+
+        dotdot.d_name.name = "..";
+        dotdot.d_name.len = 2;
+
+        lock_kernel();
+        if (!udf_find_entry(child->d_inode, &dotdot, &fibh, &cfi))
+                goto out_unlock;
+
+        if (fibh.sbh != fibh.ebh)
+                brelse(fibh.ebh);
+        brelse(fibh.sbh);
+
+        inode = udf_iget(child->d_inode->i_sb,
+                         lelb_to_cpu(cfi.icb.extLocation));
+        if (!inode)
+                goto out_unlock;
+        unlock_kernel();
+
+        parent = d_alloc_anon(inode);
+        if (!parent) {
+                iput(inode);
+                parent = ERR_PTR(-ENOMEM);
+        }
+
+        return parent;
+out_unlock:
+        unlock_kernel();
+        return ERR_PTR(-EACCES);
+}
+
+
+static struct dentry *udf_nfs_get_inode(struct super_block *sb, u32 block,
+                                        u16 partref, __u32 generation)
+{
+        struct inode *inode;
+        struct dentry *result;
+        kernel_lb_addr loc;
+
+        if (block == 0)
+                return ERR_PTR(-ESTALE);
+
+        loc.logicalBlockNum = block;
+        loc.partitionReferenceNum = partref;
+        inode = udf_iget(sb, loc);
+
+        if (inode == NULL)
+                return ERR_PTR(-ENOMEM);
+
+        if (generation && inode->i_generation != generation) {
+                iput(inode);
+                return ERR_PTR(-ESTALE);
+        }
+        result = d_alloc_anon(inode);
+        if (!result) {
+                iput(inode);
+                return ERR_PTR(-ENOMEM);
+        }
+        return result;
+}
+
+static struct dentry *udf_fh_to_dentry(struct super_block *sb,
+                                       struct fid *fid, int fh_len, int fh_type)
+{
+        if ((fh_len != 3 && fh_len != 5) ||
+            (fh_type != FILEID_UDF_WITH_PARENT &&
+             fh_type != FILEID_UDF_WITHOUT_PARENT))
+                return NULL;
+
+        return udf_nfs_get_inode(sb, fid->udf.block, fid->udf.partref,
+                        fid->udf.generation);
+}
+
+static struct dentry *udf_fh_to_parent(struct super_block *sb,
+                                       struct fid *fid, int fh_len, int fh_type)
+{
+        if (fh_len != 5 || fh_type != FILEID_UDF_WITH_PARENT)
+                return NULL;
+
+        return udf_nfs_get_inode(sb, fid->udf.parent_block,
+                                 fid->udf.parent_partref,
+                                 fid->udf.parent_generation);
+}
+static int udf_encode_fh(struct dentry *de, __u32 *fh, int *lenp,
+                         int connectable)
+{
+        int len = *lenp;
+        struct inode *inode =  de->d_inode;
+        kernel_lb_addr location = UDF_I(inode)->i_location;
+        struct fid *fid = (struct fid *)fh;
+        int type = FILEID_UDF_WITHOUT_PARENT;
+
+        if (len < 3 || (connectable && len < 5))
+                return 255;
+
+        *lenp = 3;
+        fid->udf.block = location.logicalBlockNum;
+        fid->udf.partref = location.partitionReferenceNum;
+        fid->udf.generation = inode->i_generation;
+
+        if (connectable && !S_ISDIR(inode->i_mode)) {
+                spin_lock(&de->d_lock);
+                inode = de->d_parent->d_inode;
+                location = UDF_I(inode)->i_location;
+                fid->udf.parent_block = location.logicalBlockNum;
+                fid->udf.parent_partref = location.partitionReferenceNum;
+                fid->udf.parent_generation = inode->i_generation;
+                spin_unlock(&de->d_lock);
+                *lenp = 5;
+                type = FILEID_UDF_WITH_PARENT;
+        }
+
+        return type;
+}
+
+const struct export_operations udf_export_ops = {
+        .encode_fh      = udf_encode_fh,
+        .fh_to_dentry   = udf_fh_to_dentry,
+        .fh_to_parent   = udf_fh_to_parent,
+        .get_parent     = udf_get_parent,
+};
+
 const struct inode_operations udf_dir_inode_operations = {
         .lookup                         = udf_lookup,
         .create                         = udf_create,
diff --git a/fs/udf/super.c b/fs/udf/super.c
index b564fc140fe4..260f4b82c799 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1933,6 +1933,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
 
         /* Fill in the rest of the superblock */
         sb->s_op = &udf_sb_ops;
+        sb->s_export_op = &udf_export_ops;
         sb->dq_op = NULL;
         sb->s_dirt = 0;
         sb->s_magic = UDF_SUPER_MAGIC;
diff --git a/fs/udf/udfdecl.h b/fs/udf/udfdecl.h
index f3f45d029277..8fa9c2d70911 100644
--- a/fs/udf/udfdecl.h
+++ b/fs/udf/udfdecl.h
@@ -73,6 +73,7 @@ struct task_struct;
 struct buffer_head;
 struct super_block;
 
+extern const struct export_operations udf_export_ops;
 extern const struct inode_operations udf_dir_inode_operations;
 extern const struct file_operations udf_dir_operations;
 extern const struct inode_operations udf_file_inode_operations;
diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h
index de8387b7ceb6..f5abd1306638 100644
--- a/include/linux/exportfs.h
+++ b/include/linux/exportfs.h
@@ -33,6 +33,19 @@ enum fid_type {
          * 32 bit parent directory inode number.
          */
         FILEID_INO32_GEN_PARENT = 2,
+
+        /*
+         * 32 bit block number, 16 bit partition reference,
+         * 16 bit unused, 32 bit generation number.
+         */
+        FILEID_UDF_WITHOUT_PARENT = 0x51,
+
+        /*
+         * 32 bit block number, 16 bit partition reference,
+         * 16 bit unused, 32 bit generation number,
+         * 32 bit parent block number, 32 bit parent generation number
+         */
+        FILEID_UDF_WITH_PARENT = 0x52,
 };
 
 struct fid {
@@ -43,6 +56,14 @@ struct fid {
                         u32 parent_ino;
                         u32 parent_gen;
                 } i32;
+                struct {
+                        u32 block;
+                        u16 partref;
+                        u16 parent_partref;
+                        u32 generation;
+                        u32 parent_block;
+                        u32 parent_generation;
+                } udf;
                 __u32 raw[0];
         };
 };