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erofs: make filesystem exportable

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Implement export operations in order to make EROFS support accessing
inodes with filehandles so that it can be exported via NFS and used
by overlayfs.

Without this patch, 'exportfs -rv' will report:
exportfs: /root/erofs_mp does not support NFS export

Also tested with unionmount-testsuite and the testcase below passes now:
./run --ov --erofs --verify hard-link

For more details about the testcase, see:
https://github.com/amir73il/unionmount-testsuite/pull/6

Signed-off-by: Hongnan Li <hongnan.li@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20220425040712.91685-1-hongnan.li@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Hongnan Li 2022-04-25 12:07:12 +08:00 committed by Gao Xiang
parent dcbe6803ff
commit 3e917cc305
3 changed files with 43 additions and 4 deletions
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2
fs/erofs/internal.h
View file

@ -484,7 +484,7 @@ int erofs_getattr(struct user_namespace *mnt_userns, const struct path *path,
/* namei.c */
extern const struct inode_operations erofs_dir_iops;
int erofs_namei(struct inode *dir, struct qstr *name,
int erofs_namei(struct inode *dir, const struct qstr *name,
erofs_nid_t *nid, unsigned int *d_type);
/* dir.c */

5
fs/erofs/namei.c
View file

@ -165,9 +165,8 @@ static void *find_target_block_classic(struct erofs_buf *target,
return candidate;
}
int erofs_namei(struct inode *dir,
struct qstr *name,
erofs_nid_t *nid, unsigned int *d_type)
int erofs_namei(struct inode *dir, const struct qstr *name, erofs_nid_t *nid,
unsigned int *d_type)
{
int ndirents;
struct erofs_buf buf = __EROFS_BUF_INITIALIZER;

40
fs/erofs/super.c
View file

@ -13,6 +13,7 @@
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/dax.h>
#include <linux/exportfs.h>
#include "xattr.h"
#define CREATE_TRACE_POINTS
@ -577,6 +578,44 @@ static int erofs_init_managed_cache(struct super_block *sb)
static int erofs_init_managed_cache(struct super_block *sb) { return 0; }
#endif
static struct inode *erofs_nfs_get_inode(struct super_block *sb,
u64 ino, u32 generation)
{
return erofs_iget(sb, ino, false);
}
static struct dentry *erofs_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,
erofs_nfs_get_inode);
}
static struct dentry *erofs_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,
erofs_nfs_get_inode);
}
static struct dentry *erofs_get_parent(struct dentry *child)
{
erofs_nid_t nid;
unsigned int d_type;
int err;
err = erofs_namei(d_inode(child), &dotdot_name, &nid, &d_type);
if (err)
return ERR_PTR(err);
return d_obtain_alias(erofs_iget(child->d_sb, nid, d_type == FT_DIR));
}
static const struct export_operations erofs_export_ops = {
.fh_to_dentry = erofs_fh_to_dentry,
.fh_to_parent = erofs_fh_to_parent,
.get_parent = erofs_get_parent,
};
static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct inode *inode;
@ -619,6 +658,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_op = &erofs_sops;
sb->s_xattr = erofs_xattr_handlers;
sb->s_export_op = &erofs_export_ops;
if (test_opt(&sbi->opt, POSIX_ACL))
sb->s_flags |= SB_POSIXACL;