xfs: new export ops

This one is a lot more complicated than the previous ones.  XFS already had a
very clever scheme for supporting 64bit inode numbers in filehandles, and I've
reworked this to be some kind of a prototype for the generic 64bit inode
filehandle support.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Neil Brown <neilb@suse.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: David Chinner <dgc@sgi.com>
Cc: Timothy Shimmin <tes@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 130 insertions, 124 deletions

diff --git a/fs/xfs/linux-2.6/xfs_export.c b/fs/xfs/linux-2.6/xfs_export.c
index 3586c7a28d2c..7178d61f002e 100644
--- a/fs/xfs/linux-2.6/xfs_export.c
+++ b/fs/xfs/linux-2.6/xfs_export.c
@@ -33,62 +33,25 @@
 static struct dentry dotdot = { .d_name.name = "..", .d_name.len = 2, };
 
 /*
- * XFS encodes and decodes the fileid portion of NFS filehandles
- * itself instead of letting the generic NFS code do it.  This
- * allows filesystems with 64 bit inode numbers to be exported.
- *
- * Note that a side effect is that xfs_vget() won't be passed a
- * zero inode/generation pair under normal circumstances.  As
- * however a malicious client could send us such data, the check
- * remains in that code.
+ * Note that we only accept fileids which are long enough rather than allow
+ * the parent generation number to default to zero.  XFS considers zero a
+ * valid generation number not an invalid/wildcard value.
  */
-
-STATIC struct dentry *
-xfs_fs_decode_fh(
-        struct super_block      *sb,
-        __u32                   *fh,
-        int                     fh_len,
-        int                     fileid_type,
-        int (*acceptable)(
-                void            *context,
-                struct dentry   *de),
-        void                    *context)
+static int xfs_fileid_length(int fileid_type)
 {
-        xfs_fid_t               ifid;
-        xfs_fid_t               pfid;
-        void                    *parent = NULL;
-        int                     is64 = 0;
-        __u32                   *p = fh;
-
-#if XFS_BIG_INUMS
-        is64 = (fileid_type & XFS_FILEID_TYPE_64FLAG);
-        fileid_type &= ~XFS_FILEID_TYPE_64FLAG;
-#endif
-
-        /*
-         * Note that we only accept fileids which are long enough
-         * rather than allow the parent generation number to default
-         * to zero.  XFS considers zero a valid generation number not
-         * an invalid/wildcard value.  There's little point printk'ing
-         * a warning here as we don't have the client information
-         * which would make such a warning useful.
-         */
-        if (fileid_type > 2 ||
-            fh_len < xfs_fileid_length((fileid_type == 2), is64))
-                return NULL;
-
-        p = xfs_fileid_decode_fid2(p, &ifid, is64);
-
-        if (fileid_type == 2) {
-                p = xfs_fileid_decode_fid2(p, &pfid, is64);
-                parent = &pfid;
+        switch (fileid_type) {
+        case FILEID_INO32_GEN:
+                return 2;
+        case FILEID_INO32_GEN_PARENT:
+                return 4;
+        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
+                return 3;
+        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+                return 6;
         }
-
-        fh = (__u32 *)&ifid;
-        return sb->s_export_op->find_exported_dentry(sb, fh, parent, acceptable, context);
+        return 255; /* invalid */
 }
 
-
 STATIC int
 xfs_fs_encode_fh(
         struct dentry           *dentry,
@@ -96,21 +59,21 @@ xfs_fs_encode_fh(
         int                     *max_len,
         int                     connectable)
 {
+        struct fid              *fid = (struct fid *)fh;
+        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fh;
         struct inode            *inode = dentry->d_inode;
-        int                     type = 1;
-        __u32                   *p = fh;
+        int                     fileid_type;
         int                     len;
-        int                     is64 = 0;
-#if XFS_BIG_INUMS
-        if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS)) {
-                /* filesystem may contain 64bit inode numbers */
-                is64 = XFS_FILEID_TYPE_64FLAG;
-        }
-#endif
 
         /* Directories don't need their parent encoded, they have ".." */
         if (S_ISDIR(inode->i_mode))
-            connectable = 0;
+                fileid_type = FILEID_INO32_GEN;
+        else
+                fileid_type = FILEID_INO32_GEN_PARENT;
+
+        /* filesystem may contain 64bit inode numbers */
+        if (!(XFS_M(inode->i_sb)->m_flags & XFS_MOUNT_SMALL_INUMS))
+                fileid_type |= XFS_FILEID_TYPE_64FLAG;
 
         /*
          * Only encode if there is enough space given.  In practice
@@ -118,39 +81,118 @@ xfs_fs_encode_fh(
          * over NFSv2 with the subtree_check export option; the other
          * seven combinations work.  The real answer is "don't use v2".
          */
-        len = xfs_fileid_length(connectable, is64);
+        len = xfs_fileid_length(fileid_type);
         if (*max_len < len)
                 return 255;
         *max_len = len;
 
-        p = xfs_fileid_encode_inode(p, inode, is64);
-        if (connectable) {
+        switch (fileid_type) {
+        case FILEID_INO32_GEN_PARENT:
                 spin_lock(&dentry->d_lock);
-                p = xfs_fileid_encode_inode(p, dentry->d_parent->d_inode, is64);
+                fid->i32.parent_ino = dentry->d_parent->d_inode->i_ino;
+                fid->i32.parent_gen = dentry->d_parent->d_inode->i_generation;
                 spin_unlock(&dentry->d_lock);
-                type = 2;
+                /*FALLTHRU*/
+        case FILEID_INO32_GEN:
+                fid->i32.ino = inode->i_ino;
+                fid->i32.gen = inode->i_generation;
+                break;
+        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+                spin_lock(&dentry->d_lock);
+                fid64->parent_ino = dentry->d_parent->d_inode->i_ino;
+                fid64->parent_gen = dentry->d_parent->d_inode->i_generation;
+                spin_unlock(&dentry->d_lock);
+                /*FALLTHRU*/
+        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
+                fid64->ino = inode->i_ino;
+                fid64->gen = inode->i_generation;
+                break;
         }
-        BUG_ON((p - fh) != len);
-        return type | is64;
+
+        return fileid_type;
 }
 
-STATIC struct dentry *
-xfs_fs_get_dentry(
+STATIC struct inode *
+xfs_nfs_get_inode(
         struct super_block      *sb,
-        void                    *data)
-{
+        u64                     ino,
+        u32                     generation)
+ {
+        xfs_fid_t               xfid;
         bhv_vnode_t             *vp;
-        struct inode            *inode;
-        struct dentry           *result;
         int                     error;
 
-        error = xfs_vget(XFS_M(sb), &vp, data);
-        if (error || vp == NULL)
-                return ERR_PTR(-ESTALE) ;
+        xfid.fid_len = sizeof(xfs_fid_t) - sizeof(xfid.fid_len);
+        xfid.fid_pad = 0;
+        xfid.fid_ino = ino;
+        xfid.fid_gen = generation;
 
-        inode = vn_to_inode(vp);
+        error = xfs_vget(XFS_M(sb), &vp, &xfid);
+        if (error)
+                return ERR_PTR(-error);
+
+        return vp ? vn_to_inode(vp) : NULL;
+}
+
+STATIC struct dentry *
+xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
+                 int fh_len, int fileid_type)
+{
+        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
+        struct inode            *inode = NULL;
+        struct dentry           *result;
+
+        if (fh_len < xfs_fileid_length(fileid_type))
+                return NULL;
+
+        switch (fileid_type) {
+        case FILEID_INO32_GEN_PARENT:
+        case FILEID_INO32_GEN:
+                inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
+                break;
+        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+        case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
+                inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
+                break;
+        }
+
+        if (!inode)
+                return NULL;
+        if (IS_ERR(inode))
+                return ERR_PTR(PTR_ERR(inode));
+        result = d_alloc_anon(inode);
+        if (!result) {
+                iput(inode);
+                return ERR_PTR(-ENOMEM);
+        }
+        return result;
+}
+
+STATIC struct dentry *
+xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
+                 int fh_len, int fileid_type)
+{
+        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
+        struct inode            *inode = NULL;
+        struct dentry           *result;
+
+        switch (fileid_type) {
+        case FILEID_INO32_GEN_PARENT:
+                inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
+                                              fid->i32.parent_gen);
+                break;
+        case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+                inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
+                                              fid64->parent_gen);
+                break;
+        }
+
+        if (!inode)
+                return NULL;
+        if (IS_ERR(inode))
+                return ERR_PTR(PTR_ERR(inode));
         result = d_alloc_anon(inode);
-        if (!result) {
+        if (!result) {
                 iput(inode);
                 return ERR_PTR(-ENOMEM);
         }
@@ -179,8 +221,8 @@ xfs_fs_get_parent(
 }
 
 struct export_operations xfs_export_operations = {
-        .decode_fh              = xfs_fs_decode_fh,
         .encode_fh              = xfs_fs_encode_fh,
+        .fh_to_dentry           = xfs_fs_fh_to_dentry,
+        .fh_to_parent           = xfs_fs_fh_to_parent,
         .get_parent             = xfs_fs_get_parent,
-        .get_dentry             = xfs_fs_get_dentry,
 };
diff --git a/fs/xfs/linux-2.6/xfs_export.h b/fs/xfs/linux-2.6/xfs_export.h
index 2f36071a86f7..3272b6ae7a35 100644
--- a/fs/xfs/linux-2.6/xfs_export.h
+++ b/fs/xfs/linux-2.6/xfs_export.h
@@ -59,50 +59,14 @@
  * a subdirectory) or use the "fsid" export option.
  */
 
+struct xfs_fid64 {
+        u64 ino;
+        u32 gen;
+        u64 parent_ino;
+        u32 parent_gen;
+} __attribute__((packed));
+
 /* This flag goes on the wire.  Don't play with it. */
 #define XFS_FILEID_TYPE_64FLAG  0x80    /* NFS fileid has 64bit inodes */
 
-/* Calculate the length in u32 units of the fileid data */
-static inline int
-xfs_fileid_length(int hasparent, int is64)
-{
-        return hasparent ? (is64 ? 6 : 4) : (is64 ? 3 : 2);
-}
-
-/*
- * Decode encoded inode information (either for the inode itself
- * or the parent) into an xfs_fid_t structure.  Advances and
- * returns the new data pointer
- */
-static inline __u32 *
-xfs_fileid_decode_fid2(__u32 *p, xfs_fid_t *fid, int is64)
-{
-        fid->fid_len = sizeof(xfs_fid_t) - sizeof(fid->fid_len);
-        fid->fid_pad = 0;
-        fid->fid_ino = *p++;
-#if XFS_BIG_INUMS
-        if (is64)
-                fid->fid_ino |= (((__u64)(*p++)) << 32);
-#endif
-        fid->fid_gen = *p++;
-        return p;
-}
-
-/*
- * Encode inode information (either for the inode itself or the
- * parent) into a fileid buffer.  Advances and returns the new
- * data pointer.
- */
-static inline __u32 *
-xfs_fileid_encode_inode(__u32 *p, struct inode *inode, int is64)
-{
-        *p++ = (__u32)inode->i_ino;
-#if XFS_BIG_INUMS
-        if (is64)
-                *p++ = (__u32)(inode->i_ino >> 32);
-#endif
-        *p++ = inode->i_generation;
-        return p;
-}
-
 #endif  /* __XFS_EXPORT_H__ */