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authorSteven J. Magnani <steve@digidescorp.com>2012-10-04 17:14:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-06 03:05:09 +0900
commit7669e8fb09da47dd45c07a51394f01031ea81da8 (patch)
tree1112667a0606e27999a18b8dae574ae8ad01a151 /fs/fat/inode.c
parent21b6633d516c4f5d03ec02ede6374e320191003f (diff)
downloadlinux-7669e8fb09da47dd45c07a51394f01031ea81da8.tar.bz2
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>
Diffstat (limited to 'fs/fat/inode.c')
-rw-r--r--fs/fat/inode.c71
1 files changed, 64 insertions, 7 deletions
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 169f6ebddf96..5741b11650f1 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -281,15 +281,42 @@ static inline unsigned long fat_hash(loff_t i_pos)
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 @@ void fat_detach(struct inode *inode)
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 @@ static void init_once(void *foo)
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 @@ 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;
@@ -655,8 +703,8 @@ static const struct super_operations fat_sops = {
};
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 @@ static int fat_show_options(struct seq_file *m, struct dentry *root)
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 @@ enum {
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 @@ static const match_table_t fat_tokens = {
{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 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
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 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
case Opt_discard:
opts->discard = 1;
break;
+ case Opt_nfs:
+ opts->nfs = 1;
+ break;
/* obsolete mount options */
case Opt_obsolete:
@@ -1313,6 +1368,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
/* 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 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
}
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");