Commit 7669e8fb authored by Steven J. Magnani's avatar Steven J. Magnani Committed by Linus Torvalds

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: 's avatarSteven J. Magnani <steve@digidescorp.com>
Acked-by: 's avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 21b6633d
......@@ -872,21 +872,23 @@ static int fat_get_short_entry(struct inode *dir, loff_t *pos,
}
/*
* The ".." entry can not provide the "struct fat_slot_info" informations
* for inode. So, this function provide the some informations only.
* The ".." entry can not provide the "struct fat_slot_info" information
* for inode, nor a usable i_pos. So, this function provides some information
* only.
*
* Since this function walks through the on-disk inodes within a directory,
* callers are responsible for taking any locks necessary to prevent the
* directory from changing.
*/
int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
struct msdos_dir_entry **de, loff_t *i_pos)
struct msdos_dir_entry **de)
{
loff_t offset;
loff_t offset = 0;
offset = 0;
*bh = NULL;
*de = NULL;
while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME)) {
*i_pos = fat_make_i_pos(dir->i_sb, *bh, *de);
if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
return 0;
}
}
return -ENOENT;
}
......
......@@ -5,6 +5,7 @@
#include <linux/string.h>
#include <linux/nls.h>
#include <linux/fs.h>
#include <linux/hash.h>
#include <linux/mutex.h>
#include <linux/ratelimit.h>
#include <linux/msdos_fs.h>
......@@ -46,7 +47,8 @@ struct fat_mount_options {
usefree:1, /* Use free_clusters for FAT32 */
tz_utc:1, /* Filesystem timestamps are in UTC */
rodir:1, /* allow ATTR_RO for directory */
discard:1; /* Issue discard requests on deletions */
discard:1, /* Issue discard requests on deletions */
nfs:1; /* Do extra work needed for NFS export */
};
#define FAT_HASH_BITS 8
......@@ -88,6 +90,9 @@ struct msdos_sb_info {
spinlock_t inode_hash_lock;
struct hlist_head inode_hashtable[FAT_HASH_SIZE];
spinlock_t dir_hash_lock;
struct hlist_head dir_hashtable[FAT_HASH_SIZE];
};
#define FAT_CACHE_VALID 0 /* special case for valid cache */
......@@ -110,6 +115,7 @@ struct msdos_inode_info {
int i_attrs; /* unused attribute bits */
loff_t i_pos; /* on-disk position of directory entry or 0 */
struct hlist_node i_fat_hash; /* hash by i_location */
struct hlist_node i_dir_hash; /* hash by i_logstart */
struct rw_semaphore truncate_lock; /* protect bmap against truncate */
struct inode vfs_inode;
};
......@@ -262,7 +268,7 @@ extern int fat_subdirs(struct inode *dir);
extern int fat_scan(struct inode *dir, const unsigned char *name,
struct fat_slot_info *sinfo);
extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
struct msdos_dir_entry **de, loff_t *i_pos);
struct msdos_dir_entry **de);
extern int fat_alloc_new_dir(struct inode *dir, struct timespec *ts);
extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
struct fat_slot_info *sinfo);
......@@ -341,18 +347,9 @@ 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)
static inline unsigned long fat_dir_hash(int logstart)
{
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;
return hash_32(logstart, FAT_HASH_BITS);
}
/* fat/misc.c */
......@@ -382,10 +379,10 @@ 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_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);
/* helper for printk */
......
......@@ -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");
......
......@@ -440,7 +440,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
struct inode *old_inode, *new_inode;
struct fat_slot_info old_sinfo, sinfo;
struct timespec ts;
loff_t dotdot_i_pos, new_i_pos;
loff_t new_i_pos;
int err, old_attrs, is_dir, update_dotdot, corrupt = 0;
old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
......@@ -456,8 +456,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
is_dir = S_ISDIR(old_inode->i_mode);
update_dotdot = (is_dir && old_dir != new_dir);
if (update_dotdot) {
if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de,
&dotdot_i_pos) < 0) {
if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
err = -EIO;
goto out;
}
......
......@@ -914,7 +914,7 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *old_inode, *new_inode;
struct fat_slot_info old_sinfo, sinfo;
struct timespec ts;
loff_t dotdot_i_pos, new_i_pos;
loff_t new_i_pos;
int err, is_dir, update_dotdot, corrupt = 0;
struct super_block *sb = old_dir->i_sb;
......@@ -929,8 +929,7 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
is_dir = S_ISDIR(old_inode->i_mode);
update_dotdot = (is_dir && old_dir != new_dir);
if (update_dotdot) {
if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de,
&dotdot_i_pos) < 0) {
if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
err = -EIO;
goto out;
}
......
......@@ -14,47 +14,46 @@
#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.
/**
* Look up a directory inode given its starting cluster.
*/
int
fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
static struct inode *fat_dget(struct super_block *sb, int i_logstart)
{
int len = *lenp;
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
loff_t i_pos;
struct msdos_sb_info *sbi = MSDOS_SB(sb);
struct hlist_head *head;
struct hlist_node *_p;
struct msdos_inode_info *i;
struct inode *inode = NULL;
if (len < 5) {
*lenp = 5;
return 255; /* no room */
head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
spin_lock(&sbi->dir_hash_lock);
hlist_for_each_entry(i, _p, head, i_dir_hash) {
BUG_ON(i->vfs_inode.i_sb != sb);
if (i->i_logstart != i_logstart)
continue;
inode = igrab(&i->vfs_inode);
if (inode)
break;
}
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;
spin_unlock(&sbi->dir_hash_lock);
return inode;
}
static int fat_is_valid_fh(int fh_len, int fh_type)
static struct inode *fat_nfs_get_inode(struct super_block *sb,
u64 ino, u32 generation)
{
return ((fh_len >= 5) && (fh_type == 3));
struct inode *inode;
if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
return NULL;
inode = ilookup(sb, ino);
if (inode && generation && (inode->i_generation != generation)) {
iput(inode);
inode = NULL;
}
return inode;
}
/**
......@@ -64,57 +63,19 @@ static int fat_is_valid_fh(int fh_len, int fh_type)
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;
}
}
return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
fat_nfs_get_inode);
}
/*
* 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 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,
int fh_len, int fh_type)
{
return generic_fh_to_parent(sb, fid, fh_len, fh_type,
fat_nfs_get_inode);
}
/*
......@@ -128,24 +89,13 @@ 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;
struct inode *parent_inode = NULL;
lock_super(sb);
err = fat_get_dotdot_entry(child_dir->d_inode, &bh, &de, &i_pos);
if (err) {
parent = ERR_PTR(err);
goto out;
if (!fat_get_dotdot_entry(child_dir->d_inode, &bh, &de)) {
int parent_logstart = fat_get_start(MSDOS_SB(sb), de);
parent_inode = fat_dget(sb, parent_logstart);
}
inode = fat_build_inode(sb, de, i_pos);
parent = d_obtain_alias(inode);
out:
brelse(bh);
unlock_super(sb);
return parent;
return d_obtain_alias(parent_inode);
}
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