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fat: restructure export_operations
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Define two nfs export_operation structures,one for 'stale_rw' mounts and
the other for 'nostale_ro'.  The latter uses i_pos as a basis for encoding
and decoding file handles.

Also, assign i_pos to kstat->ino.  The logic for rebuilding the inode is
added in the subsequent patches.

Signed-off-by: Namjae Jeon <[email protected]>
Signed-off-by: Ravishankar N <[email protected]>
Signed-off-by: Amit Sahrawat <[email protected]>
Acked-by: OGAWA Hirofumi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@namjaejeon @torvalds
namjaejeon authored and torvalds committed Apr 30, 2013
1 parent e22a444 commit ea3983a
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Showing 5 changed files with 147 additions and 20 deletions.
8 changes: 2 additions & 6 deletions fs/fat/fat.h
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Original file line number Diff line number Diff line change
Expand Up @@ -406,12 +406,8 @@ int fat_cache_init(void);
void fat_cache_destroy(void);

/* fat/nfs.c */
struct fid;
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);
extern const struct export_operations fat_export_ops;
extern const struct export_operations fat_export_ops_nostale;

/* helper for printk */
typedef unsigned long long llu;
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5 changes: 5 additions & 0 deletions fs/fat/file.c
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Original file line number Diff line number Diff line change
Expand Up @@ -306,6 +306,11 @@ int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
struct inode *inode = dentry->d_inode;
generic_fillattr(inode, stat);
stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;

if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
/* Use i_pos for ino. This is used as fileid of nfs. */
stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
}
return 0;
}
EXPORT_SYMBOL_GPL(fat_getattr);
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13 changes: 4 additions & 9 deletions fs/fat/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@
#include <linux/pagemap.h>
#include <linux/mpage.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/parser.h>
Expand Down Expand Up @@ -748,12 +747,6 @@ static const struct super_operations fat_sops = {
.show_options = fat_show_options,
};

static const struct export_operations fat_export_ops = {
.fh_to_dentry = fat_fh_to_dentry,
.fh_to_parent = fat_fh_to_parent,
.get_parent = fat_get_parent,
};

static int fat_show_options(struct seq_file *m, struct dentry *root)
{
struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
Expand Down Expand Up @@ -1177,8 +1170,10 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
if (opts->unicode_xlate)
opts->utf8 = 0;
if (opts->nfs == FAT_NFS_NOSTALE_RO)
if (opts->nfs == FAT_NFS_NOSTALE_RO) {
sb->s_flags |= MS_RDONLY;
sb->s_export_op = &fat_export_ops_nostale;
}

return 0;
}
Expand All @@ -1189,7 +1184,7 @@ static int fat_read_root(struct inode *inode)
struct msdos_sb_info *sbi = MSDOS_SB(sb);
int error;

MSDOS_I(inode)->i_pos = 0;
MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
inode->i_uid = sbi->options.fs_uid;
inode->i_gid = sbi->options.fs_gid;
inode->i_version++;
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130 changes: 125 additions & 5 deletions fs/fat/nfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,18 @@
#include <linux/exportfs.h>
#include "fat.h"

struct fat_fid {
u32 i_gen;
u32 i_pos_low;
u16 i_pos_hi;
u16 parent_i_pos_hi;
u32 parent_i_pos_low;
u32 parent_i_gen;
};

#define FAT_FID_SIZE_WITHOUT_PARENT 3
#define FAT_FID_SIZE_WITH_PARENT (sizeof(struct fat_fid)/sizeof(u32))

/**
* Look up a directory inode given its starting cluster.
*/
Expand All @@ -38,8 +50,8 @@ static struct inode *fat_dget(struct super_block *sb, int i_logstart)
return inode;
}

static struct inode *fat_nfs_get_inode(struct super_block *sb,
u64 ino, u32 generation)
static struct inode *__fat_nfs_get_inode(struct super_block *sb,
u64 ino, u32 generation, loff_t i_pos)
{
struct inode *inode;

Expand All @@ -55,35 +67,130 @@ static struct inode *fat_nfs_get_inode(struct super_block *sb,
return inode;
}

static struct inode *fat_nfs_get_inode(struct super_block *sb,
u64 ino, u32 generation)
{

return __fat_nfs_get_inode(sb, ino, generation, 0);
}

static int
fat_encode_fh_nostale(struct inode *inode, __u32 *fh, int *lenp,
struct inode *parent)
{
int len = *lenp;
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
struct fat_fid *fid = (struct fat_fid *) fh;
loff_t i_pos;
int type = FILEID_FAT_WITHOUT_PARENT;

if (parent) {
if (len < FAT_FID_SIZE_WITH_PARENT) {
*lenp = FAT_FID_SIZE_WITH_PARENT;
return FILEID_INVALID;
}
} else {
if (len < FAT_FID_SIZE_WITHOUT_PARENT) {
*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
return FILEID_INVALID;
}
}

i_pos = fat_i_pos_read(sbi, inode);
*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
fid->i_gen = inode->i_generation;
fid->i_pos_low = i_pos & 0xFFFFFFFF;
fid->i_pos_hi = (i_pos >> 32) & 0xFFFF;
if (parent) {
i_pos = fat_i_pos_read(sbi, parent);
fid->parent_i_pos_hi = (i_pos >> 32) & 0xFFFF;
fid->parent_i_pos_low = i_pos & 0xFFFFFFFF;
fid->parent_i_gen = parent->i_generation;
type = FILEID_FAT_WITH_PARENT;
*lenp = FAT_FID_SIZE_WITH_PARENT;
}

return type;
}

/**
* 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,
static struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
fat_nfs_get_inode);
}

static struct dentry *fat_fh_to_dentry_nostale(struct super_block *sb,
struct fid *fh, int fh_len,
int fh_type)
{
struct inode *inode = NULL;
struct fat_fid *fid = (struct fat_fid *)fh;
loff_t i_pos;

switch (fh_type) {
case FILEID_FAT_WITHOUT_PARENT:
if (fh_len < FAT_FID_SIZE_WITHOUT_PARENT)
return NULL;
break;
case FILEID_FAT_WITH_PARENT:
if (fh_len < FAT_FID_SIZE_WITH_PARENT)
return NULL;
break;
default:
return NULL;
}
i_pos = fid->i_pos_hi;
i_pos = (i_pos << 32) | (fid->i_pos_low);
inode = __fat_nfs_get_inode(sb, 0, fid->i_gen, i_pos);

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,
static 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);
}

static struct dentry *fat_fh_to_parent_nostale(struct super_block *sb,
struct fid *fh, int fh_len,
int fh_type)
{
struct inode *inode = NULL;
struct fat_fid *fid = (struct fat_fid *)fh;
loff_t i_pos;

if (fh_len < FAT_FID_SIZE_WITH_PARENT)
return NULL;

switch (fh_type) {
case FILEID_FAT_WITH_PARENT:
i_pos = fid->parent_i_pos_hi;
i_pos = (i_pos << 32) | (fid->parent_i_pos_low);
inode = __fat_nfs_get_inode(sb, 0, fid->parent_i_gen, i_pos);
break;
}

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)
static struct dentry *fat_get_parent(struct dentry *child_dir)
{
struct super_block *sb = child_dir->d_sb;
struct buffer_head *bh = NULL;
Expand All @@ -98,3 +205,16 @@ struct dentry *fat_get_parent(struct dentry *child_dir)

return d_obtain_alias(parent_inode);
}

const struct export_operations fat_export_ops = {
.fh_to_dentry = fat_fh_to_dentry,
.fh_to_parent = fat_fh_to_parent,
.get_parent = fat_get_parent,
};

const struct export_operations fat_export_ops_nostale = {
.encode_fh = fat_encode_fh_nostale,
.fh_to_dentry = fat_fh_to_dentry_nostale,
.fh_to_parent = fat_fh_to_parent_nostale,
.get_parent = fat_get_parent,
};
11 changes: 11 additions & 0 deletions include/linux/exportfs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -84,6 +84,17 @@ enum fid_type {
*/
FILEID_NILFS_WITH_PARENT = 0x62,

/*
* 32 bit generation number, 40 bit i_pos.
*/
FILEID_FAT_WITHOUT_PARENT = 0x71,

/*
* 32 bit generation number, 40 bit i_pos,
* 32 bit parent generation number, 40 bit parent i_pos
*/
FILEID_FAT_WITH_PARENT = 0x72,

/*
* Filesystems must not use 0xff file ID.
*/
Expand Down

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