fat (exportfs): fix dentry reconnection
Maintain an index of directory inodes by starting cluster, so that
fat_get_parent() can return the proper cached inode rather than inventing
one that cannot be traced back to the filesystem root.
Add a new msdos/vfat binary mount option "nfs" so that FAT filesystems
that are _not_ exported via NFS are not saddled with maintenance of an
index they will never use.
Finally, simplify NFS file handle generation and lookups. An
ext2-congruent implementation is adequate for FAT needs.
Signed-off-by: Steven J. Magnani <steve@digidescorp.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>
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 169f6eb..5741b11 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -281,15 +281,42 @@
return hash_32(i_pos, FAT_HASH_BITS);
}
+static void dir_hash_init(struct super_block *sb)
+{
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+ int i;
+
+ spin_lock_init(&sbi->dir_hash_lock);
+ for (i = 0; i < FAT_HASH_SIZE; i++)
+ INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
+}
+
void fat_attach(struct inode *inode, loff_t i_pos)
{
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
- struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
- spin_lock(&sbi->inode_hash_lock);
- MSDOS_I(inode)->i_pos = i_pos;
- hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
- spin_unlock(&sbi->inode_hash_lock);
+ if (inode->i_ino != MSDOS_ROOT_INO) {
+ struct hlist_head *head = sbi->inode_hashtable
+ + fat_hash(i_pos);
+
+ spin_lock(&sbi->inode_hash_lock);
+ MSDOS_I(inode)->i_pos = i_pos;
+ hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
+ spin_unlock(&sbi->inode_hash_lock);
+ }
+
+ /* If NFS support is enabled, cache the mapping of start cluster
+ * to directory inode. This is used during reconnection of
+ * dentries to the filesystem root.
+ */
+ if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
+ struct hlist_head *d_head = sbi->dir_hashtable;
+ d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
+
+ spin_lock(&sbi->dir_hash_lock);
+ hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
+ spin_unlock(&sbi->dir_hash_lock);
+ }
}
EXPORT_SYMBOL_GPL(fat_attach);
@@ -300,6 +327,12 @@
MSDOS_I(inode)->i_pos = 0;
hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
spin_unlock(&sbi->inode_hash_lock);
+
+ if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
+ spin_lock(&sbi->dir_hash_lock);
+ hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
+ spin_unlock(&sbi->dir_hash_lock);
+ }
}
EXPORT_SYMBOL_GPL(fat_detach);
@@ -504,6 +537,7 @@
ei->cache_valid_id = FAT_CACHE_VALID + 1;
INIT_LIST_HEAD(&ei->cache_lru);
INIT_HLIST_NODE(&ei->i_fat_hash);
+ INIT_HLIST_NODE(&ei->i_dir_hash);
inode_init_once(&ei->vfs_inode);
}
@@ -562,6 +596,20 @@
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;
@@ -655,8 +703,8 @@
};
static const struct export_operations fat_export_ops = {
- .encode_fh = fat_encode_fh,
.fh_to_dentry = fat_fh_to_dentry,
+ .fh_to_parent = fat_fh_to_parent,
.get_parent = fat_get_parent,
};
@@ -706,6 +754,8 @@
seq_puts(m, ",usefree");
if (opts->quiet)
seq_puts(m, ",quiet");
+ if (opts->nfs)
+ seq_puts(m, ",nfs");
if (opts->showexec)
seq_puts(m, ",showexec");
if (opts->sys_immutable)
@@ -750,7 +800,7 @@
Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
- Opt_err_panic, Opt_err_ro, Opt_discard, Opt_err,
+ Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_err,
};
static const match_table_t fat_tokens = {
@@ -779,6 +829,7 @@
{Opt_err_panic, "errors=panic"},
{Opt_err_ro, "errors=remount-ro"},
{Opt_discard, "discard"},
+ {Opt_nfs, "nfs"},
{Opt_obsolete, "conv=binary"},
{Opt_obsolete, "conv=text"},
{Opt_obsolete, "conv=auto"},
@@ -859,6 +910,7 @@
opts->numtail = 1;
opts->usefree = opts->nocase = 0;
opts->tz_utc = 0;
+ opts->nfs = 0;
opts->errors = FAT_ERRORS_RO;
*debug = 0;
@@ -1023,6 +1075,9 @@
case Opt_discard:
opts->discard = 1;
break;
+ case Opt_nfs:
+ opts->nfs = 1;
+ break;
/* obsolete mount options */
case Opt_obsolete:
@@ -1313,6 +1368,7 @@
/* set up enough so that it can read an inode */
fat_hash_init(sb);
+ dir_hash_init(sb);
fat_ent_access_init(sb);
/*
@@ -1367,6 +1423,7 @@
}
error = -ENOMEM;
insert_inode_hash(root_inode);
+ fat_attach(root_inode, 0);
sb->s_root = d_make_root(root_inode);
if (!sb->s_root) {
fat_msg(sb, KERN_ERR, "get root inode failed");