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>
This commit is contained in:
Steven J. Magnani
Linus Torvalds
parent
21b6633d51
commit
7669e8fb09
20
fs/fat/dir.c
20
fs/fat/dir.c
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@ -872,21 +872,23 @@ static int fat_get_short_entry(struct inode *dir, loff_t *pos,
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}
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/*
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* The ".." entry can not provide the "struct fat_slot_info" informations
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* for inode. So, this function provide the some informations only.
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* The ".." entry can not provide the "struct fat_slot_info" information
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* for inode, nor a usable i_pos. So, this function provides some information
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* only.
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*
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* Since this function walks through the on-disk inodes within a directory,
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* callers are responsible for taking any locks necessary to prevent the
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* directory from changing.
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*/
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int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
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struct msdos_dir_entry **de, loff_t *i_pos)
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struct msdos_dir_entry **de)
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{
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loff_t offset;
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loff_t offset = 0;
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offset = 0;
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*bh = NULL;
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*de = NULL;
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while (fat_get_short_entry(dir, &offset, bh, de) >= 0) {
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if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME)) {
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*i_pos = fat_make_i_pos(dir->i_sb, *bh, *de);
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if (!strncmp((*de)->name, MSDOS_DOTDOT, MSDOS_NAME))
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return 0;
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}
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}
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return -ENOENT;
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}
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27
fs/fat/fat.h
27
fs/fat/fat.h
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@ -5,6 +5,7 @@
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#include <linux/string.h>
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#include <linux/nls.h>
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#include <linux/fs.h>
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#include <linux/hash.h>
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#include <linux/mutex.h>
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#include <linux/ratelimit.h>
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#include <linux/msdos_fs.h>
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@ -46,7 +47,8 @@ struct fat_mount_options {
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usefree:1, /* Use free_clusters for FAT32 */
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tz_utc:1, /* Filesystem timestamps are in UTC */
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rodir:1, /* allow ATTR_RO for directory */
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discard:1; /* Issue discard requests on deletions */
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discard:1, /* Issue discard requests on deletions */
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nfs:1; /* Do extra work needed for NFS export */
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};
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#define FAT_HASH_BITS 8
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@ -88,6 +90,9 @@ struct msdos_sb_info {
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spinlock_t inode_hash_lock;
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struct hlist_head inode_hashtable[FAT_HASH_SIZE];
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spinlock_t dir_hash_lock;
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struct hlist_head dir_hashtable[FAT_HASH_SIZE];
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};
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#define FAT_CACHE_VALID 0 /* special case for valid cache */
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@ -110,6 +115,7 @@ struct msdos_inode_info {
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int i_attrs; /* unused attribute bits */
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loff_t i_pos; /* on-disk position of directory entry or 0 */
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struct hlist_node i_fat_hash; /* hash by i_location */
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struct hlist_node i_dir_hash; /* hash by i_logstart */
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struct rw_semaphore truncate_lock; /* protect bmap against truncate */
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struct inode vfs_inode;
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};
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@ -262,7 +268,7 @@ extern int fat_subdirs(struct inode *dir);
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extern int fat_scan(struct inode *dir, const unsigned char *name,
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struct fat_slot_info *sinfo);
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extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
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struct msdos_dir_entry **de, loff_t *i_pos);
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struct msdos_dir_entry **de);
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extern int fat_alloc_new_dir(struct inode *dir, struct timespec *ts);
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extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
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struct fat_slot_info *sinfo);
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@ -341,18 +347,9 @@ extern int fat_fill_super(struct super_block *sb, void *data, int silent,
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extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
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struct inode *i2);
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static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
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struct inode *inode)
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static inline unsigned long fat_dir_hash(int logstart)
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{
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loff_t i_pos;
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#if BITS_PER_LONG == 32
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spin_lock(&sbi->inode_hash_lock);
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#endif
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i_pos = MSDOS_I(inode)->i_pos;
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#if BITS_PER_LONG == 32
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spin_unlock(&sbi->inode_hash_lock);
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#endif
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return i_pos;
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return hash_32(logstart, FAT_HASH_BITS);
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}
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/* fat/misc.c */
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@ -382,10 +379,10 @@ void fat_cache_destroy(void);
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/* fat/nfs.c */
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struct fid;
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extern int fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp,
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struct inode *parent);
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extern struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
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int fh_len, int fh_type);
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extern struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
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int fh_len, int fh_type);
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extern struct dentry *fat_get_parent(struct dentry *child_dir);
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/* helper for printk */
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@ -281,15 +281,42 @@ static inline unsigned long fat_hash(loff_t i_pos)
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return hash_32(i_pos, FAT_HASH_BITS);
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}
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static void dir_hash_init(struct super_block *sb)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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int i;
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spin_lock_init(&sbi->dir_hash_lock);
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for (i = 0; i < FAT_HASH_SIZE; i++)
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INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
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}
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void fat_attach(struct inode *inode, loff_t i_pos)
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{
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struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
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struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
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spin_lock(&sbi->inode_hash_lock);
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MSDOS_I(inode)->i_pos = i_pos;
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hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
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spin_unlock(&sbi->inode_hash_lock);
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if (inode->i_ino != MSDOS_ROOT_INO) {
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struct hlist_head *head = sbi->inode_hashtable
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+ fat_hash(i_pos);
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spin_lock(&sbi->inode_hash_lock);
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MSDOS_I(inode)->i_pos = i_pos;
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hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
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spin_unlock(&sbi->inode_hash_lock);
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}
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/* If NFS support is enabled, cache the mapping of start cluster
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* to directory inode. This is used during reconnection of
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* dentries to the filesystem root.
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*/
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if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
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struct hlist_head *d_head = sbi->dir_hashtable;
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d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
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spin_lock(&sbi->dir_hash_lock);
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hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
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spin_unlock(&sbi->dir_hash_lock);
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}
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}
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EXPORT_SYMBOL_GPL(fat_attach);
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@ -300,6 +327,12 @@ void fat_detach(struct inode *inode)
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MSDOS_I(inode)->i_pos = 0;
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hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
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spin_unlock(&sbi->inode_hash_lock);
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if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
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spin_lock(&sbi->dir_hash_lock);
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hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
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spin_unlock(&sbi->dir_hash_lock);
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}
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}
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EXPORT_SYMBOL_GPL(fat_detach);
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@ -504,6 +537,7 @@ static void init_once(void *foo)
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ei->cache_valid_id = FAT_CACHE_VALID + 1;
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INIT_LIST_HEAD(&ei->cache_lru);
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INIT_HLIST_NODE(&ei->i_fat_hash);
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INIT_HLIST_NODE(&ei->i_dir_hash);
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inode_init_once(&ei->vfs_inode);
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}
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@ -562,6 +596,20 @@ static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
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return 0;
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}
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static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
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struct inode *inode)
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{
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loff_t i_pos;
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#if BITS_PER_LONG == 32
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spin_lock(&sbi->inode_hash_lock);
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#endif
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i_pos = MSDOS_I(inode)->i_pos;
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#if BITS_PER_LONG == 32
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spin_unlock(&sbi->inode_hash_lock);
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#endif
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return i_pos;
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}
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static int __fat_write_inode(struct inode *inode, int wait)
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{
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struct super_block *sb = inode->i_sb;
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@ -655,8 +703,8 @@ static const struct super_operations fat_sops = {
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};
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static const struct export_operations fat_export_ops = {
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.encode_fh = fat_encode_fh,
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.fh_to_dentry = fat_fh_to_dentry,
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.fh_to_parent = fat_fh_to_parent,
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.get_parent = fat_get_parent,
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};
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@ -706,6 +754,8 @@ static int fat_show_options(struct seq_file *m, struct dentry *root)
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seq_puts(m, ",usefree");
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if (opts->quiet)
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seq_puts(m, ",quiet");
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if (opts->nfs)
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seq_puts(m, ",nfs");
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if (opts->showexec)
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seq_puts(m, ",showexec");
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if (opts->sys_immutable)
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@ -750,7 +800,7 @@ enum {
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Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
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Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
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Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
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Opt_err_panic, Opt_err_ro, Opt_discard, Opt_err,
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Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_err,
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};
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static const match_table_t fat_tokens = {
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@ -779,6 +829,7 @@ static const match_table_t fat_tokens = {
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{Opt_err_panic, "errors=panic"},
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{Opt_err_ro, "errors=remount-ro"},
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{Opt_discard, "discard"},
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{Opt_nfs, "nfs"},
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{Opt_obsolete, "conv=binary"},
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{Opt_obsolete, "conv=text"},
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{Opt_obsolete, "conv=auto"},
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@ -859,6 +910,7 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
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opts->numtail = 1;
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opts->usefree = opts->nocase = 0;
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opts->tz_utc = 0;
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opts->nfs = 0;
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opts->errors = FAT_ERRORS_RO;
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*debug = 0;
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@ -1023,6 +1075,9 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
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case Opt_discard:
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opts->discard = 1;
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break;
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case Opt_nfs:
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opts->nfs = 1;
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break;
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/* obsolete mount options */
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case Opt_obsolete:
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@ -1313,6 +1368,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
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/* set up enough so that it can read an inode */
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fat_hash_init(sb);
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dir_hash_init(sb);
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fat_ent_access_init(sb);
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/*
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@ -1367,6 +1423,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
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}
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error = -ENOMEM;
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insert_inode_hash(root_inode);
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fat_attach(root_inode, 0);
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sb->s_root = d_make_root(root_inode);
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if (!sb->s_root) {
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fat_msg(sb, KERN_ERR, "get root inode failed");
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@ -440,7 +440,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
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struct inode *old_inode, *new_inode;
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struct fat_slot_info old_sinfo, sinfo;
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struct timespec ts;
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loff_t dotdot_i_pos, new_i_pos;
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loff_t new_i_pos;
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int err, old_attrs, is_dir, update_dotdot, corrupt = 0;
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old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
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@ -456,8 +456,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
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is_dir = S_ISDIR(old_inode->i_mode);
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update_dotdot = (is_dir && old_dir != new_dir);
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if (update_dotdot) {
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if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de,
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&dotdot_i_pos) < 0) {
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if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
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err = -EIO;
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goto out;
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}
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@ -914,7 +914,7 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
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struct inode *old_inode, *new_inode;
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struct fat_slot_info old_sinfo, sinfo;
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struct timespec ts;
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loff_t dotdot_i_pos, new_i_pos;
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loff_t new_i_pos;
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int err, is_dir, update_dotdot, corrupt = 0;
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struct super_block *sb = old_dir->i_sb;
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@ -929,8 +929,7 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
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is_dir = S_ISDIR(old_inode->i_mode);
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update_dotdot = (is_dir && old_dir != new_dir);
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if (update_dotdot) {
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if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de,
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&dotdot_i_pos) < 0) {
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if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
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err = -EIO;
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goto out;
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}
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150
fs/fat/nfs.c
150
fs/fat/nfs.c
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@ -14,47 +14,46 @@
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#include <linux/exportfs.h>
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#include "fat.h"
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/*
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* a FAT file handle with fhtype 3 is
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* 0/ i_ino - for fast, reliable lookup if still in the cache
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* 1/ i_generation - to see if i_ino is still valid
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* bit 0 == 0 iff directory
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* 2/ i_pos(8-39) - if ino has changed, but still in cache
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* 3/ i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
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* 4/ i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
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*
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* Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
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* i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
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* of i_logstart is used to store the directory entry offset.
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/**
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* Look up a directory inode given its starting cluster.
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*/
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int
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fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
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static struct inode *fat_dget(struct super_block *sb, int i_logstart)
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{
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int len = *lenp;
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struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
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loff_t i_pos;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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struct hlist_head *head;
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struct hlist_node *_p;
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struct msdos_inode_info *i;
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struct inode *inode = NULL;
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if (len < 5) {
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*lenp = 5;
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return 255; /* no room */
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head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
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spin_lock(&sbi->dir_hash_lock);
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hlist_for_each_entry(i, _p, head, i_dir_hash) {
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BUG_ON(i->vfs_inode.i_sb != sb);
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if (i->i_logstart != i_logstart)
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continue;
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inode = igrab(&i->vfs_inode);
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if (inode)
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break;
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}
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i_pos = fat_i_pos_read(sbi, inode);
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*lenp = 5;
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fh[0] = inode->i_ino;
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fh[1] = inode->i_generation;
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fh[2] = i_pos >> 8;
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fh[3] = ((i_pos & 0xf0) << 24) | MSDOS_I(inode)->i_logstart;
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fh[4] = (i_pos & 0x0f) << 28;
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if (parent)
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fh[4] |= MSDOS_I(parent)->i_logstart;
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return 3;
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spin_unlock(&sbi->dir_hash_lock);
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return inode;
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}
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static int fat_is_valid_fh(int fh_len, int fh_type)
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static struct inode *fat_nfs_get_inode(struct super_block *sb,
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u64 ino, u32 generation)
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{
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return ((fh_len >= 5) && (fh_type == 3));
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struct inode *inode;
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|
||||
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;
|
||||
return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
|
||||
fat_nfs_get_inode);
|
||||
}
|
||||
|
||||
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 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);
|
||||
}
|
||||
|
|
|
|||
Reference in New Issue