4 files changed, 174 insertions, 131 deletions

diff --git a/fs/fat/Makefile b/fs/fat/Makefile
index e06190322c1c..964b634f6667 100644
--- a/fs/fat/Makefile
+++ b/fs/fat/Makefile
@@ -6,6 +6,6 @@ obj-$(CONFIG_FAT_FS) += fat.o
 obj-$(CONFIG_VFAT_FS) += vfat.o
 obj-$(CONFIG_MSDOS_FS) += msdos.o
 
-fat-y := cache.o dir.o fatent.o file.o inode.o misc.o
+fat-y := cache.o dir.o fatent.o file.o inode.o misc.o nfs.o
 vfat-y := namei_vfat.o
 msdos-y := namei_msdos.o
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 7d8e0dcac5d5..fb95939ff870 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -341,6 +341,20 @@ extern int fat_fill_super(struct super_block *sb, void *data, int silent,
 
 extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
                             struct inode *i2);
+static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
+                                    struct inode *inode)
+{
+        loff_t i_pos;
+#if BITS_PER_LONG == 32
+        spin_lock(&sbi->inode_hash_lock);
+#endif
+        i_pos = MSDOS_I(inode)->i_pos;
+#if BITS_PER_LONG == 32
+        spin_unlock(&sbi->inode_hash_lock);
+#endif
+        return i_pos;
+}
+
 /* fat/misc.c */
 extern __printf(3, 4) __cold
 void __fat_fs_error(struct super_block *sb, int report, const char *fmt, ...);
@@ -366,6 +380,14 @@ extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
 int fat_cache_init(void);
 void fat_cache_destroy(void);
 
+/* fat/nfs.c */
+struct fid;
+extern int fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp,
+                         struct inode *parent);
+extern struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
+                                       int fh_len, int fh_type);
+extern struct dentry *fat_get_parent(struct dentry *child_dir);
+
 /* helper for printk */
 typedef unsigned long long      llu;
 
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 4e5a6ac54ebd..169f6ebddf96 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -562,20 +562,6 @@ static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
         return 0;
 }
 
-static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
-                                    struct inode *inode)
-{
-        loff_t i_pos;
-#if BITS_PER_LONG == 32
-        spin_lock(&sbi->inode_hash_lock);
-#endif
-        i_pos = MSDOS_I(inode)->i_pos;
-#if BITS_PER_LONG == 32
-        spin_unlock(&sbi->inode_hash_lock);
-#endif
-        return i_pos;
-}
-
 static int __fat_write_inode(struct inode *inode, int wait)
 {
         struct super_block *sb = inode->i_sb;
@@ -668,122 +654,6 @@ static const struct super_operations fat_sops = {
         .show_options   = fat_show_options,
 };
 
-/*
- * a FAT file handle with fhtype 3 is
- *  0/  i_ino - for fast, reliable lookup if still in the cache
- *  1/  i_generation - to see if i_ino is still valid
- *          bit 0 == 0 iff directory
- *  2/  i_pos(8-39) - if ino has changed, but still in cache
- *  3/  i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
- *  4/  i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
- *
- * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
- * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
- * of i_logstart is used to store the directory entry offset.
- */
-
-static struct dentry *fat_fh_to_dentry(struct super_block *sb,
-                struct fid *fid, int fh_len, int fh_type)
-{
-        struct inode *inode = NULL;
-        u32 *fh = fid->raw;
-
-        if (fh_len < 5 || fh_type != 3)
-                return NULL;
-
-        inode = ilookup(sb, fh[0]);
-        if (!inode || inode->i_generation != fh[1]) {
-                if (inode)
-                        iput(inode);
-                inode = NULL;
-        }
-        if (!inode) {
-                loff_t i_pos;
-                int i_logstart = fh[3] & 0x0fffffff;
-
-                i_pos = (loff_t)fh[2] << 8;
-                i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28);
-
-                /* try 2 - see if i_pos is in F-d-c
-                 * require i_logstart to be the same
-                 * Will fail if you truncate and then re-write
-                 */
-
-                inode = fat_iget(sb, i_pos);
-                if (inode && MSDOS_I(inode)->i_logstart != i_logstart) {
-                        iput(inode);
-                        inode = NULL;
-                }
-        }
-
-        /*
-         * For now, do nothing if the inode is not found.
-         *
-         * What we could do is:
-         *
-         *      - follow the file starting at fh[4], and record the ".." entry,
-         *        and the name of the fh[2] entry.
-         *      - then follow the ".." file finding the next step up.
-         *
-         * This way we build a path to the root of the tree. If this works, we
-         * lookup the path and so get this inode into the cache.  Finally try
-         * the fat_iget lookup again.  If that fails, then we are totally out
-         * of luck.  But all that is for another day
-         */
-        return d_obtain_alias(inode);
-}
-
-static int
-fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
-{
-        int len = *lenp;
-        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
-        loff_t i_pos;
-
-        if (len < 5) {
-                *lenp = 5;
-                return 255; /* no room */
-        }
-
-        i_pos = fat_i_pos_read(sbi, inode);
-        *lenp = 5;
-        fh[0] = inode->i_ino;
-        fh[1] = inode->i_generation;
-        fh[2] = i_pos >> 8;
-        fh[3] = ((i_pos & 0xf0) << 24) | MSDOS_I(inode)->i_logstart;
-        fh[4] = (i_pos & 0x0f) << 28;
-        if (parent)
-                fh[4] |= MSDOS_I(parent)->i_logstart;
-        return 3;
-}
-
-static struct dentry *fat_get_parent(struct dentry *child)
-{
-        struct super_block *sb = child->d_sb;
-        struct buffer_head *bh;
-        struct msdos_dir_entry *de;
-        loff_t i_pos;
-        struct dentry *parent;
-        struct inode *inode;
-        int err;
-
-        lock_super(sb);
-
-        err = fat_get_dotdot_entry(child->d_inode, &bh, &de, &i_pos);
-        if (err) {
-                parent = ERR_PTR(err);
-                goto out;
-        }
-        inode = fat_build_inode(sb, de, i_pos);
-        brelse(bh);
-
-        parent = d_obtain_alias(inode);
-out:
-        unlock_super(sb);
-
-        return parent;
-}
-
 static const struct export_operations fat_export_ops = {
         .encode_fh      = fat_encode_fh,
         .fh_to_dentry   = fat_fh_to_dentry,
diff --git a/fs/fat/nfs.c b/fs/fat/nfs.c
new file mode 100644
index 000000000000..21609a1e9355
--- /dev/null
+++ b/fs/fat/nfs.c
@@ -0,0 +1,151 @@
+/* fs/fat/nfs.c
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/exportfs.h>
+#include "fat.h"
+
+/*
+ * a FAT file handle with fhtype 3 is
+ *  0/  i_ino - for fast, reliable lookup if still in the cache
+ *  1/  i_generation - to see if i_ino is still valid
+ *          bit 0 == 0 iff directory
+ *  2/  i_pos(8-39) - if ino has changed, but still in cache
+ *  3/  i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
+ *  4/  i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
+ *
+ * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
+ * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
+ * of i_logstart is used to store the directory entry offset.
+ */
+
+int
+fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
+{
+        int len = *lenp;
+        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+        loff_t i_pos;
+
+        if (len < 5) {
+                *lenp = 5;
+                return 255; /* no room */
+        }
+
+        i_pos = fat_i_pos_read(sbi, inode);
+        *lenp = 5;
+        fh[0] = inode->i_ino;
+        fh[1] = inode->i_generation;
+        fh[2] = i_pos >> 8;
+        fh[3] = ((i_pos & 0xf0) << 24) | MSDOS_I(inode)->i_logstart;
+        fh[4] = (i_pos & 0x0f) << 28;
+        if (parent)
+                fh[4] |= MSDOS_I(parent)->i_logstart;
+        return 3;
+}
+
+static int fat_is_valid_fh(int fh_len, int fh_type)
+{
+        return ((fh_len >= 5) && (fh_type == 3));
+}
+
+/**
+ * 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,
+                                int fh_len, int fh_type)
+{
+        struct inode *inode = NULL;
+        u32 *fh = fid->raw;
+        loff_t i_pos;
+        unsigned long i_ino;
+        __u32 i_generation;
+        int i_logstart;
+
+        if (!fat_is_valid_fh(fh_len, fh_type))
+                return NULL;
+
+        i_ino = fh[0];
+        i_generation = fh[1];
+        i_logstart = fh[3] & 0x0fffffff;
+
+        /* Try i_ino lookup first - fastest and most reliable */
+        inode = ilookup(sb, i_ino);
+        if (inode && (inode->i_generation != i_generation)) {
+                iput(inode);
+                inode = NULL;
+        }
+        if (!inode) {
+                i_pos = (loff_t)fh[2] << 8;
+                i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28);
+
+                /* try 2 - see if i_pos is in F-d-c
+                 * require i_logstart to be the same
+                 * Will fail if you truncate and then re-write
+                 */
+
+                inode = fat_iget(sb, i_pos);
+                if (inode && MSDOS_I(inode)->i_logstart != i_logstart) {
+                        iput(inode);
+                        inode = NULL;
+                }
+        }
+
+        /*
+         * For now, do nothing if the inode is not found.
+         *
+         * What we could do is:
+         *
+         *      - follow the file starting at fh[4], and record the ".." entry,
+         *        and the name of the fh[2] entry.
+         *      - then follow the ".." file finding the next step up.
+         *
+         * This way we build a path to the root of the tree. If this works, we
+         * lookup the path and so get this inode into the cache.  Finally try
+         * the fat_iget lookup again.  If that fails, then we are totally out
+         * of luck.  But all that is for another day
+         */
+        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)
+{
+        struct super_block *sb = child_dir->d_sb;
+        struct buffer_head *bh = NULL;
+        struct msdos_dir_entry *de;
+        loff_t i_pos;
+        struct dentry *parent;
+        struct inode *inode;
+        int err;
+
+        lock_super(sb);
+
+        err = fat_get_dotdot_entry(child_dir->d_inode, &bh, &de, &i_pos);
+        if (err) {
+                parent = ERR_PTR(err);
+                goto out;
+        }
+        inode = fat_build_inode(sb, de, i_pos);
+
+        parent = d_obtain_alias(inode);
+out:
+        brelse(bh);
+        unlock_super(sb);
+
+        return parent;
+}