[PATCH] erofs: make filesystem exportable

[PATCH] erofs: make filesystem exportable

[Hongnan Li]

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>
---
 fs/erofs/internal.h |  2 +-
 fs/erofs/namei.c    |  5 ++---
 fs/erofs/super.c    | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 5298c4ee277d..12c65f647324 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -509,7 +509,7 @@ 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 */
diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c
index 554efa363317..fd75506799c4 100644
--- a/fs/erofs/namei.c
+++ b/fs/erofs/namei.c
@@ -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;
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 0c4b41130c2f..17ad271677b6 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -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);
+}
+
+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;
@@ -618,6 +657,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_time_gran = 1;
 
 	sb->s_op = &erofs_sops;
+	sb->s_export_op = &erofs_export_ops;
 	sb->s_xattr = erofs_xattr_handlers;
 
 	if (test_opt(&sbi->opt, POSIX_ACL))
-- 
2.19.1.6.gb485710b

Re: [PATCH] erofs: make filesystem exportable

[kernel test robot]

Hi Hongnan,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on xiang-erofs/dev-test]
[also build test WARNING on v5.18-rc3 next-20220422]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/Hongnan-Li/erofs-make-filesystem-exportable/20220424-211653
base:   https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git dev-test
config: hexagon-buildonly-randconfig-r005-20220424 (https://download.01.org/0day-ci/archive/20220424/202204242236.0aTl5THK-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 1cddcfdc3c683b393df1a5c9063252eb60e52818)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/c0fc15c5ccc4a5090cc32744ba63bde8ea558ac7
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Hongnan-Li/erofs-make-filesystem-exportable/20220424-211653
        git checkout c0fc15c5ccc4a5090cc32744ba63bde8ea558ac7
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash fs/erofs/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> fs/erofs/super.c:601:16: warning: no previous prototype for function 'erofs_get_parent' [-Wmissing-prototypes]
   struct dentry *erofs_get_parent(struct dentry *child)
                  ^
   fs/erofs/super.c:601:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   struct dentry *erofs_get_parent(struct dentry *child)
   ^
   static 
   1 warning generated.


vim +/erofs_get_parent +601 fs/erofs/super.c

   600	
 > 601	struct dentry *erofs_get_parent(struct dentry *child)
   602	{
   603		erofs_nid_t nid;
   604		unsigned int d_type;
   605		int err;
   606	
   607		err = erofs_namei(d_inode(child), &dotdot_name, &nid, &d_type);
   608		if (err)
   609			return ERR_PTR(err);
   610		return d_obtain_alias(erofs_iget(child->d_sb, nid, d_type == FT_DIR));
   611	}
   612	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH] erofs: make filesystem exportable

[kernel test robot]

Hi Hongnan,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on xiang-erofs/dev-test]
[also build test WARNING on v5.18-rc3 next-20220422]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/intel-lab-lkp/linux/commits/Hongnan-Li/erofs-make-filesystem-exportable/20220424-211653
base:   https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git dev-test
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20220424/202204242223.Hf6HESVt-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/c0fc15c5ccc4a5090cc32744ba63bde8ea558ac7
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Hongnan-Li/erofs-make-filesystem-exportable/20220424-211653
        git checkout c0fc15c5ccc4a5090cc32744ba63bde8ea558ac7
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash fs/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> fs/erofs/super.c:601:16: warning: no previous prototype for 'erofs_get_parent' [-Wmissing-prototypes]
     601 | struct dentry *erofs_get_parent(struct dentry *child)
         |                ^~~~~~~~~~~~~~~~


vim +/erofs_get_parent +601 fs/erofs/super.c

   600	
 > 601	struct dentry *erofs_get_parent(struct dentry *child)
   602	{
   603		erofs_nid_t nid;
   604		unsigned int d_type;
   605		int err;
   606	
   607		err = erofs_namei(d_inode(child), &dotdot_name, &nid, &d_type);
   608		if (err)
   609			return ERR_PTR(err);
   610		return d_obtain_alias(erofs_iget(child->d_sb, nid, d_type == FT_DIR));
   611	}
   612	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

[PATCH v2 resend] erofs: make filesystem exportable

[Hongnan Li]

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>
---
 fs/erofs/internal.h |  2 +-
 fs/erofs/namei.c    |  5 ++---
 fs/erofs/super.c    | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 5298c4ee277d..12c65f647324 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -509,7 +509,7 @@ 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 */
diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c
index 554efa363317..fd75506799c4 100644
--- a/fs/erofs/namei.c
+++ b/fs/erofs/namei.c
@@ -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;
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 0c4b41130c2f..1c77b7acabd0 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -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;
@@ -618,6 +657,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
 	sb->s_time_gran = 1;
 
 	sb->s_op = &erofs_sops;
+	sb->s_export_op = &erofs_export_ops;
 	sb->s_xattr = erofs_xattr_handlers;
 
 	if (test_opt(&sbi->opt, POSIX_ACL))
-- 
2.19.1.6.gb485710b

Re: [PATCH v2 resend] erofs: make filesystem exportable

[Gao Xiang]

On Mon, Apr 25, 2022 at 12:07:12PM +0800, Hongnan Li wrote:
> 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>
> ---
>  fs/erofs/internal.h |  2 +-
>  fs/erofs/namei.c    |  5 ++---
>  fs/erofs/super.c    | 40 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 43 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 5298c4ee277d..12c65f647324 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -509,7 +509,7 @@ 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 */
> diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c
> index 554efa363317..fd75506799c4 100644
> --- a/fs/erofs/namei.c
> +++ b/fs/erofs/namei.c
> @@ -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;
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index 0c4b41130c2f..1c77b7acabd0 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -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;
> @@ -618,6 +657,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>  	sb->s_time_gran = 1;
>  
>  	sb->s_op = &erofs_sops;
> +	sb->s_export_op = &erofs_export_ops;

I might need to rearrange this part later since it has a slight conflict
with the fscache patchset. Otherwise looks good to me,

Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Thanks,
Gao Xiang

>  	sb->s_xattr = erofs_xattr_handlers;
>  
>  	if (test_opt(&sbi->opt, POSIX_ACL))
> -- 
> 2.19.1.6.gb485710b

Re: [PATCH v2 resend] erofs: make filesystem exportable

[Chao Yu]

On 2022/4/25 12:07, Hongnan Li wrote:
> 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: Chao Yu <chao@kernel.org>

Thanks,