fat: restructure export_operations

Define two nfs export_operation structures,one for 'stale_rw' mounts and
the other for 'nostale_ro'.  The latter uses i_pos as a basis for encoding
and decoding file handles.

Also, assign i_pos to kstat->ino.  The logic for rebuilding the inode is
added in the subsequent patches.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ravishankar N <ravi.n1@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 136 insertions, 20 deletions

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 980c0346c168..c517fc066cf7 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -406,12 +406,8 @@ int fat_cache_init(void);
 void fat_cache_destroy(void);
 
 /* fat/nfs.c */
-struct fid;
-extern struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
-                                       int fh_len, int fh_type);
-extern struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
-                                       int fh_len, int fh_type);
-extern struct dentry *fat_get_parent(struct dentry *child_dir);
+extern const struct export_operations fat_export_ops;
+extern const struct export_operations fat_export_ops_nostale;
 
 /* helper for printk */
 typedef unsigned long long      llu;
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 3978f8ca1823..b0b632e50ddb 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -306,6 +306,11 @@ int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
         struct inode *inode = dentry->d_inode;
         generic_fillattr(inode, stat);
         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
+
+        if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
+                /* Use i_pos for ino. This is used as fileid of nfs. */
+                stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
+        }
         return 0;
 }
 EXPORT_SYMBOL_GPL(fat_getattr);
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 68cb5a6eb539..27f49f4fa0d3 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -18,7 +18,6 @@
 #include <linux/pagemap.h>
 #include <linux/mpage.h>
 #include <linux/buffer_head.h>
-#include <linux/exportfs.h>
 #include <linux/mount.h>
 #include <linux/vfs.h>
 #include <linux/parser.h>
@@ -748,12 +747,6 @@ static const struct super_operations fat_sops = {
         .show_options   = fat_show_options,
 };
 
-static const struct export_operations fat_export_ops = {
-        .fh_to_dentry   = fat_fh_to_dentry,
-        .fh_to_parent   = fat_fh_to_parent,
-        .get_parent     = fat_get_parent,
-};
-
 static int fat_show_options(struct seq_file *m, struct dentry *root)
 {
         struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
@@ -1177,8 +1170,10 @@ out:
                 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
         if (opts->unicode_xlate)
                 opts->utf8 = 0;
-        if (opts->nfs == FAT_NFS_NOSTALE_RO)
+        if (opts->nfs == FAT_NFS_NOSTALE_RO) {
                 sb->s_flags |= MS_RDONLY;
+                sb->s_export_op = &fat_export_ops_nostale;
+        }
 
         return 0;
 }
@@ -1189,7 +1184,7 @@ static int fat_read_root(struct inode *inode)
         struct msdos_sb_info *sbi = MSDOS_SB(sb);
         int error;
 
-        MSDOS_I(inode)->i_pos = 0;
+        MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
         inode->i_uid = sbi->options.fs_uid;
         inode->i_gid = sbi->options.fs_gid;
         inode->i_version++;
diff --git a/fs/fat/nfs.c b/fs/fat/nfs.c
index 499c10438ca2..d59c02543a10 100644
--- a/fs/fat/nfs.c
+++ b/fs/fat/nfs.c
@@ -14,6 +14,18 @@
 #include <linux/exportfs.h>
 #include "fat.h"
 
+struct fat_fid {
+        u32 i_gen;
+        u32 i_pos_low;
+        u16 i_pos_hi;
+        u16 parent_i_pos_hi;
+        u32 parent_i_pos_low;
+        u32 parent_i_gen;
+};
+
+#define FAT_FID_SIZE_WITHOUT_PARENT 3
+#define FAT_FID_SIZE_WITH_PARENT (sizeof(struct fat_fid)/sizeof(u32))
+
 /**
  * Look up a directory inode given its starting cluster.
  */
@@ -38,8 +50,8 @@ static struct inode *fat_dget(struct super_block *sb, int i_logstart)
         return inode;
 }
 
-static struct inode *fat_nfs_get_inode(struct super_block *sb,
-                                       u64 ino, u32 generation)
+static struct inode *__fat_nfs_get_inode(struct super_block *sb,
+                                       u64 ino, u32 generation, loff_t i_pos)
 {
         struct inode *inode;
 
@@ -55,35 +67,130 @@ static struct inode *fat_nfs_get_inode(struct super_block *sb,
         return inode;
 }
 
+static struct inode *fat_nfs_get_inode(struct super_block *sb,
+                                       u64 ino, u32 generation)
+{
+
+        return __fat_nfs_get_inode(sb, ino, generation, 0);
+}
+
+static int
+fat_encode_fh_nostale(struct inode *inode, __u32 *fh, int *lenp,
+                      struct inode *parent)
+{
+        int len = *lenp;
+        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+        struct fat_fid *fid = (struct fat_fid *) fh;
+        loff_t i_pos;
+        int type = FILEID_FAT_WITHOUT_PARENT;
+
+        if (parent) {
+                if (len < FAT_FID_SIZE_WITH_PARENT) {
+                        *lenp = FAT_FID_SIZE_WITH_PARENT;
+                        return FILEID_INVALID;
+                }
+        } else {
+                if (len < FAT_FID_SIZE_WITHOUT_PARENT) {
+                        *lenp = FAT_FID_SIZE_WITHOUT_PARENT;
+                        return FILEID_INVALID;
+                }
+        }
+
+        i_pos = fat_i_pos_read(sbi, inode);
+        *lenp = FAT_FID_SIZE_WITHOUT_PARENT;
+        fid->i_gen = inode->i_generation;
+        fid->i_pos_low = i_pos & 0xFFFFFFFF;
+        fid->i_pos_hi = (i_pos >> 32) & 0xFFFF;
+        if (parent) {
+                i_pos = fat_i_pos_read(sbi, parent);
+                fid->parent_i_pos_hi = (i_pos >> 32) & 0xFFFF;
+                fid->parent_i_pos_low = i_pos & 0xFFFFFFFF;
+                fid->parent_i_gen = parent->i_generation;
+                type = FILEID_FAT_WITH_PARENT;
+                *lenp = FAT_FID_SIZE_WITH_PARENT;
+        }
+
+        return type;
+}
+
 /**
  * Map a NFS file handle to a corresponding dentry.
  * The dentry may or may not be connected to the filesystem root.
  */
-struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
+static struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
                                 int fh_len, int fh_type)
 {
         return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                                     fat_nfs_get_inode);
 }
 
+static struct dentry *fat_fh_to_dentry_nostale(struct super_block *sb,
+                                               struct fid *fh, int fh_len,
+                                               int fh_type)
+{
+        struct inode *inode = NULL;
+        struct fat_fid *fid = (struct fat_fid *)fh;
+        loff_t i_pos;
+
+        switch (fh_type) {
+        case FILEID_FAT_WITHOUT_PARENT:
+                if (fh_len < FAT_FID_SIZE_WITHOUT_PARENT)
+                        return NULL;
+                break;
+        case FILEID_FAT_WITH_PARENT:
+                if (fh_len < FAT_FID_SIZE_WITH_PARENT)
+                        return NULL;
+                break;
+        default:
+                return NULL;
+        }
+        i_pos = fid->i_pos_hi;
+        i_pos = (i_pos << 32) | (fid->i_pos_low);
+        inode = __fat_nfs_get_inode(sb, 0, fid->i_gen, i_pos);
+
+        return d_obtain_alias(inode);
+}
+
 /*
  * Find the parent for a file specified by NFS handle.
  * This requires that the handle contain the i_ino of the parent.
  */
-struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
+static struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
                                 int fh_len, int fh_type)
 {
         return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                                     fat_nfs_get_inode);
 }
 
+static struct dentry *fat_fh_to_parent_nostale(struct super_block *sb,
+                                               struct fid *fh, int fh_len,
+                                               int fh_type)
+{
+        struct inode *inode = NULL;
+        struct fat_fid *fid = (struct fat_fid *)fh;
+        loff_t i_pos;
+
+        if (fh_len < FAT_FID_SIZE_WITH_PARENT)
+                return NULL;
+
+        switch (fh_type) {
+        case FILEID_FAT_WITH_PARENT:
+                i_pos = fid->parent_i_pos_hi;
+                i_pos = (i_pos << 32) | (fid->parent_i_pos_low);
+                inode = __fat_nfs_get_inode(sb, 0, fid->parent_i_gen, i_pos);
+                break;
+        }
+
+        return d_obtain_alias(inode);
+}
+
 /*
  * Find the parent for a directory that is not currently connected to
  * the filesystem root.
  *
  * On entry, the caller holds child_dir->d_inode->i_mutex.
  */
-struct dentry *fat_get_parent(struct dentry *child_dir)
+static struct dentry *fat_get_parent(struct dentry *child_dir)
 {
         struct super_block *sb = child_dir->d_sb;
         struct buffer_head *bh = NULL;
@@ -98,3 +205,16 @@ struct dentry *fat_get_parent(struct dentry *child_dir)
 
         return d_obtain_alias(parent_inode);
 }
+
+const struct export_operations fat_export_ops = {
+        .fh_to_dentry   = fat_fh_to_dentry,
+        .fh_to_parent   = fat_fh_to_parent,
+        .get_parent     = fat_get_parent,
+};
+
+const struct export_operations fat_export_ops_nostale = {
+        .encode_fh      = fat_encode_fh_nostale,
+        .fh_to_dentry   = fat_fh_to_dentry_nostale,
+        .fh_to_parent   = fat_fh_to_parent_nostale,
+        .get_parent     = fat_get_parent,
+};