[2/8] fs: extract simple_pin/release_fs to separate files
diff mbox series

Message ID 20200414124304.4470-3-eesposit@redhat.com
State New
Headers show
Series
  • Simplefs: group and simplify linux fs code
Related show

Commit Message

Emanuele Giuseppe Esposito April 14, 2020, 12:42 p.m. UTC
We will augment this family of functions with inode management.  To avoid
littering include/linux/fs.h and fs/libfs.c, move them to a separate header,
with a Kconfig symbol to enable them.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 drivers/gpu/drm/Kconfig         |  1 +
 drivers/gpu/drm/drm_drv.c       |  2 +-
 drivers/misc/cxl/Kconfig        |  1 +
 drivers/misc/cxl/api.c          |  1 +
 drivers/misc/ocxl/Kconfig       |  1 +
 drivers/scsi/cxlflash/ocxl_hw.c |  1 +
 fs/Kconfig                      |  3 +++
 fs/Kconfig.binfmt               |  1 +
 fs/Makefile                     |  1 +
 fs/binfmt_misc.c                |  2 +-
 fs/configfs/Kconfig             |  1 +
 fs/configfs/mount.c             |  2 +-
 fs/debugfs/inode.c              |  2 +-
 fs/libfs.c                      | 36 +------------------------------
 fs/simplefs.c                   | 38 +++++++++++++++++++++++++++++++++
 fs/tracefs/inode.c              |  2 +-
 include/linux/fs.h              |  2 --
 include/linux/simplefs.h        | 10 +++++++++
 lib/Kconfig.debug               | 16 ++++++++------
 security/Kconfig                |  1 +
 security/apparmor/apparmorfs.c  |  3 ++-
 security/inode.c                |  2 +-
 22 files changed, 79 insertions(+), 50 deletions(-)
 create mode 100644 fs/simplefs.c
 create mode 100644 include/linux/simplefs.h

Comments

Greg Kroah-Hartman April 14, 2020, 12:54 p.m. UTC | #1
On Tue, Apr 14, 2020 at 02:42:56PM +0200, Emanuele Giuseppe Esposito wrote:
> We will augment this family of functions with inode management.  To avoid
> littering include/linux/fs.h and fs/libfs.c, move them to a separate header,
> with a Kconfig symbol to enable them.
> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>

You have a lot of people on cc:, this is going to be hard for everyone
to review...


> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index d1398cef3b18..fc38a6f0fc11 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -288,12 +288,16 @@ config STRIP_ASM_SYMS
>  
>  config READABLE_ASM
>  	bool "Generate readable assembler code"
> -	depends on DEBUG_KERNEL
> -	help
> -	  Disable some compiler optimizations that tend to generate human unreadable
> -	  assembler output. This may make the kernel slightly slower, but it helps
> -	  to keep kernel developers who have to stare a lot at assembler listings
> -	  sane.
> +    depends on DEBUG_KERNEL
> +    help
> +      Disable some compiler optimizations that tend to generate human unreadable
> +      assembler output. This may make the kernel slightly slower, but it helps
> +      to keep kernel developers who have to stare a lot at assembler listings
> +      sane.
> +	  

Why did you loose the indentation here and add trailing whitespace?

> +config DEBUG_FS
> +	bool "Debug Filesystem"
> +	select SIMPLEFS
>  

We already have a DEBUG_FS config option in this file, why another one?
And what happened to the help text?

I think you need to rework your patch series to do smaller things on
each step, which would make it reviewable much easier, and prevent
mistakes like this one.

thanks,

greg k-h
Luis Chamberlain April 16, 2020, 6:52 a.m. UTC | #2
On Tue, Apr 14, 2020 at 02:42:56PM +0200, Emanuele Giuseppe Esposito wrote:
> We will augment this family of functions with inode management.  To avoid
> littering include/linux/fs.h and fs/libfs.c, move them to a separate header,
> with a Kconfig symbol to enable them.

If there are no functional changes, indicating that on the commit log
will make the review much easier.

> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index d1398cef3b18..fc38a6f0fc11 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -288,12 +288,16 @@ config STRIP_ASM_SYMS
>  
>  config READABLE_ASM
>  	bool "Generate readable assembler code"
> -	depends on DEBUG_KERNEL
> -	help
> -	  Disable some compiler optimizations that tend to generate human unreadable
> -	  assembler output. This may make the kernel slightly slower, but it helps
> -	  to keep kernel developers who have to stare a lot at assembler listings
> -	  sane.
> +    depends on DEBUG_KERNEL
> +    help
> +      Disable some compiler optimizations that tend to generate human unreadable
> +      assembler output. This may make the kernel slightly slower, but it helps
> +      to keep kernel developers who have to stare a lot at assembler listings
> +      sane.
> +	  

This minor change above should just be a separate patch. Its just noise
otherwise.

> +config DEBUG_FS
> +	bool "Debug Filesystem"
> +	select SIMPLEFS

I'm at a loss reviewing this,  my lib/Kconfig.debug already has a config
DEBUG_FS.  But above I see it is being added for the very first time.
I'm sure there is some odd conditional which is obscuring this, can
this be explained in the commit log?

  Luis
Frederic Barrat April 21, 2020, 11:19 a.m. UTC | #3
> diff --git a/drivers/misc/cxl/Kconfig b/drivers/misc/cxl/Kconfig
> index 39eec9031487..a62795079d9c 100644
> --- a/drivers/misc/cxl/Kconfig
> +++ b/drivers/misc/cxl/Kconfig
> @@ -19,6 +19,7 @@ config CXL
>   	select CXL_BASE
>   	select CXL_AFU_DRIVER_OPS
>   	select CXL_LIB
> +	select SIMPLEFS
>   	default m
>   	help
>   	  Select this option to enable driver support for IBM Coherent
> diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
> index b493de962153..0b8f8de7475a 100644
> --- a/drivers/misc/cxl/api.c
> +++ b/drivers/misc/cxl/api.c
> @@ -9,6 +9,7 @@
>   #include <misc/cxl.h>
>   #include <linux/module.h>
>   #include <linux/mount.h>
> +#include <linux/simplefs.h>
>   #include <linux/pseudo_fs.h>
>   #include <linux/sched/mm.h>
>   #include <linux/mmu_context.h>
> diff --git a/drivers/misc/ocxl/Kconfig b/drivers/misc/ocxl/Kconfig
> index 2d2266c1439e..ddd9245fff3d 100644
> --- a/drivers/misc/ocxl/Kconfig
> +++ b/drivers/misc/ocxl/Kconfig
> @@ -12,6 +12,7 @@ config OCXL
>   	depends on PPC_POWERNV && PCI && EEH
>   	select OCXL_BASE
>   	select HOTPLUG_PCI_POWERNV
> +	select SIMPLEFS


It's not clear to me the Kconfig updated is needed for the ocxl driver. 
I think it's only needed for the cxl driver.

   Fred
Emanuele Giuseppe Esposito April 21, 2020, 11:26 a.m. UTC | #4
On 4/21/20 1:19 PM, Frederic Barrat wrote:
> 
> 
>> diff --git a/drivers/misc/cxl/Kconfig b/drivers/misc/cxl/Kconfig
>> index 39eec9031487..a62795079d9c 100644
>> --- a/drivers/misc/cxl/Kconfig
>> +++ b/drivers/misc/cxl/Kconfig
>> @@ -19,6 +19,7 @@ config CXL
>>       select CXL_BASE
>>       select CXL_AFU_DRIVER_OPS
>>       select CXL_LIB
>> +    select SIMPLEFS
>>       default m
>>       help
>>         Select this option to enable driver support for IBM Coherent
>> diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
>> index b493de962153..0b8f8de7475a 100644
>> --- a/drivers/misc/cxl/api.c
>> +++ b/drivers/misc/cxl/api.c
>> @@ -9,6 +9,7 @@
>>   #include <misc/cxl.h>
>>   #include <linux/module.h>
>>   #include <linux/mount.h>
>> +#include <linux/simplefs.h>
>>   #include <linux/pseudo_fs.h>
>>   #include <linux/sched/mm.h>
>>   #include <linux/mmu_context.h>
>> diff --git a/drivers/misc/ocxl/Kconfig b/drivers/misc/ocxl/Kconfig
>> index 2d2266c1439e..ddd9245fff3d 100644
>> --- a/drivers/misc/ocxl/Kconfig
>> +++ b/drivers/misc/ocxl/Kconfig
>> @@ -12,6 +12,7 @@ config OCXL
>>       depends on PPC_POWERNV && PCI && EEH
>>       select OCXL_BASE
>>       select HOTPLUG_PCI_POWERNV
>> +    select SIMPLEFS
> 
> 
> It's not clear to me the Kconfig updated is needed for the ocxl driver. 
> I think it's only needed for the cxl driver.

I am going to get rid of the separate simplefs.c file and related 
Kconfig entry and put everything in fs/libfs.c, so this file (together 
with many others touched in this patch) won't be modified in v2.

Thanks,

Emanuele

Patch
diff mbox series

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 43594978958e..a6fe933de9da 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -14,6 +14,7 @@  menuconfig DRM
 	select I2C
 	select I2C_ALGOBIT
 	select DMA_SHARED_BUFFER
+	select SIMPLEFS
 	select SYNC_FILE
 	help
 	  Kernel-level support for the Direct Rendering Infrastructure (DRI)
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 7b1a628d1f6e..187a61091b5c 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -27,7 +27,7 @@ 
  */
 
 #include <linux/debugfs.h>
-#include <linux/fs.h>
+#include <linux/simplefs.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/mount.h>
diff --git a/drivers/misc/cxl/Kconfig b/drivers/misc/cxl/Kconfig
index 39eec9031487..a62795079d9c 100644
--- a/drivers/misc/cxl/Kconfig
+++ b/drivers/misc/cxl/Kconfig
@@ -19,6 +19,7 @@  config CXL
 	select CXL_BASE
 	select CXL_AFU_DRIVER_OPS
 	select CXL_LIB
+	select SIMPLEFS
 	default m
 	help
 	  Select this option to enable driver support for IBM Coherent
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index b493de962153..0b8f8de7475a 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -9,6 +9,7 @@ 
 #include <misc/cxl.h>
 #include <linux/module.h>
 #include <linux/mount.h>
+#include <linux/simplefs.h>
 #include <linux/pseudo_fs.h>
 #include <linux/sched/mm.h>
 #include <linux/mmu_context.h>
diff --git a/drivers/misc/ocxl/Kconfig b/drivers/misc/ocxl/Kconfig
index 2d2266c1439e..ddd9245fff3d 100644
--- a/drivers/misc/ocxl/Kconfig
+++ b/drivers/misc/ocxl/Kconfig
@@ -12,6 +12,7 @@  config OCXL
 	depends on PPC_POWERNV && PCI && EEH
 	select OCXL_BASE
 	select HOTPLUG_PCI_POWERNV
+	select SIMPLEFS
 	default m
 	help
 	  Select this option to enable the ocxl driver for Open
diff --git a/drivers/scsi/cxlflash/ocxl_hw.c b/drivers/scsi/cxlflash/ocxl_hw.c
index 7018cd802569..429f55651090 100644
--- a/drivers/scsi/cxlflash/ocxl_hw.c
+++ b/drivers/scsi/cxlflash/ocxl_hw.c
@@ -12,6 +12,7 @@ 
 #include <linux/idr.h>
 #include <linux/module.h>
 #include <linux/mount.h>
+#include <linux/simplefs.h>
 #include <linux/pseudo_fs.h>
 #include <linux/poll.h>
 #include <linux/sched/signal.h>
diff --git a/fs/Kconfig b/fs/Kconfig
index f08fbbfafd9a..a6795ae312a2 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -218,6 +218,9 @@  config HUGETLB_PAGE
 config MEMFD_CREATE
 	def_bool TMPFS || HUGETLBFS
 
+config SIMPLEFS
+	bool
+
 config ARCH_HAS_GIGANTIC_PAGE
 	bool
 
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 62dc4f577ba1..af7b765de4d3 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -176,6 +176,7 @@  config BINFMT_EM86
 
 config BINFMT_MISC
 	tristate "Kernel support for MISC binaries"
+	select SIMPLEFS
 	---help---
 	  If you say Y here, it will be possible to plug wrapper-driven binary
 	  formats into the kernel. You will like this especially when you use
diff --git a/fs/Makefile b/fs/Makefile
index 2ce5112b02c8..c5c665984b9e 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -26,6 +26,7 @@  obj-$(CONFIG_PROC_FS) += proc_namespace.o
 obj-y				+= notify/
 obj-$(CONFIG_EPOLL)		+= eventpoll.o
 obj-y				+= anon_inodes.o
+obj-$(CONFIG_SIMPLEFS)		+= simplefs.o
 obj-$(CONFIG_SIGNALFD)		+= signalfd.o
 obj-$(CONFIG_TIMERFD)		+= timerfd.o
 obj-$(CONFIG_EVENTFD)		+= eventfd.o
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index cdb45829354d..c764110f5f0b 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -25,7 +25,7 @@ 
 #include <linux/mount.h>
 #include <linux/fs_context.h>
 #include <linux/syscalls.h>
-#include <linux/fs.h>
+#include <linux/simplefs.h>
 #include <linux/uaccess.h>
 
 #include "internal.h"
diff --git a/fs/configfs/Kconfig b/fs/configfs/Kconfig
index 272b64456999..3b461e4e3989 100644
--- a/fs/configfs/Kconfig
+++ b/fs/configfs/Kconfig
@@ -1,6 +1,7 @@ 
 # SPDX-License-Identifier: GPL-2.0-only
 config CONFIGFS_FS
 	tristate "Userspace-driven configuration filesystem"
+	select SIMPLEFS
 	select SYSFS
 	help
 	  configfs is a RAM-based filesystem that provides the converse
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 0c6e8cf61953..331c2f064f02 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -10,7 +10,7 @@ 
  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  */
 
-#include <linux/fs.h>
+#include <linux/simplefs.h>
 #include <linux/module.h>
 #include <linux/mount.h>
 #include <linux/fs_context.h>
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index b7f2e971ecbc..7b9fddced48f 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -13,7 +13,7 @@ 
 #define pr_fmt(fmt)	"debugfs: " fmt
 
 #include <linux/module.h>
-#include <linux/fs.h>
+#include <linux/simplefs.h>
 #include <linux/mount.h>
 #include <linux/pagemap.h>
 #include <linux/init.h>
diff --git a/fs/libfs.c b/fs/libfs.c
index 3759fbacf522..26ec729f7bcd 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -11,6 +11,7 @@ 
 #include <linux/cred.h>
 #include <linux/mount.h>
 #include <linux/vfs.h>
+#include <linux/simplefs.h>
 #include <linux/quotaops.h>
 #include <linux/mutex.h>
 #include <linux/namei.h>
@@ -663,41 +664,6 @@  int simple_fill_super(struct super_block *s, unsigned long magic,
 }
 EXPORT_SYMBOL(simple_fill_super);
 
-static DEFINE_SPINLOCK(pin_fs_lock);
-
-int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
-{
-	struct vfsmount *mnt = NULL;
-	spin_lock(&pin_fs_lock);
-	if (unlikely(!*mount)) {
-		spin_unlock(&pin_fs_lock);
-		mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
-		if (IS_ERR(mnt))
-			return PTR_ERR(mnt);
-		spin_lock(&pin_fs_lock);
-		if (!*mount)
-			*mount = mnt;
-	}
-	mntget(*mount);
-	++*count;
-	spin_unlock(&pin_fs_lock);
-	mntput(mnt);
-	return 0;
-}
-EXPORT_SYMBOL(simple_pin_fs);
-
-void simple_release_fs(struct vfsmount **mount, int *count)
-{
-	struct vfsmount *mnt;
-	spin_lock(&pin_fs_lock);
-	mnt = *mount;
-	if (!--*count)
-		*mount = NULL;
-	spin_unlock(&pin_fs_lock);
-	mntput(mnt);
-}
-EXPORT_SYMBOL(simple_release_fs);
-
 /**
  * simple_read_from_buffer - copy data from the buffer to user space
  * @to: the user space buffer to read to
diff --git a/fs/simplefs.c b/fs/simplefs.c
new file mode 100644
index 000000000000..226d18963801
--- /dev/null
+++ b/fs/simplefs.c
@@ -0,0 +1,38 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/simplefs.h>
+#include <linux/mount.h>
+
+static DEFINE_SPINLOCK(pin_fs_lock);
+
+int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
+{
+	struct vfsmount *mnt = NULL;
+	spin_lock(&pin_fs_lock);
+	if (unlikely(!*mount)) {
+		spin_unlock(&pin_fs_lock);
+		mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
+		if (IS_ERR(mnt))
+			return PTR_ERR(mnt);
+		spin_lock(&pin_fs_lock);
+		if (!*mount)
+			*mount = mnt;
+	}
+	mntget(*mount);
+	++*count;
+	spin_unlock(&pin_fs_lock);
+	mntput(mnt);
+	return 0;
+}
+EXPORT_SYMBOL(simple_pin_fs);
+
+void simple_release_fs(struct vfsmount **mount, int *count)
+{
+	struct vfsmount *mnt;
+	spin_lock(&pin_fs_lock);
+	mnt = *mount;
+	if (!--*count)
+		*mount = NULL;
+	spin_unlock(&pin_fs_lock);
+	mntput(mnt);
+}
+EXPORT_SYMBOL(simple_release_fs);
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 0ee8c6dfb036..4353ca81e1d7 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -10,7 +10,7 @@ 
  */
 
 #include <linux/module.h>
-#include <linux/fs.h>
+#include <linux/simplefs.h>
 #include <linux/mount.h>
 #include <linux/kobject.h>
 #include <linux/namei.h>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4f6f59b4f22a..55b679b89c8a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3363,8 +3363,6 @@  struct tree_descr { const char *name; const struct file_operations *ops; int mod
 struct dentry *d_alloc_name(struct dentry *, const char *);
 extern int simple_fill_super(struct super_block *, unsigned long,
 			     const struct tree_descr *);
-extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
-extern void simple_release_fs(struct vfsmount **mount, int *count);
 
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 			loff_t *ppos, const void *from, size_t available);
diff --git a/include/linux/simplefs.h b/include/linux/simplefs.h
new file mode 100644
index 000000000000..1076a44db308
--- /dev/null
+++ b/include/linux/simplefs.h
@@ -0,0 +1,10 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SIMPLEFS_H
+#define _LINUX_SIMPLEFS_H
+
+#include <linux/fs.h>
+
+extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
+extern void simple_release_fs(struct vfsmount **mount, int *count);
+
+#endif
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d1398cef3b18..fc38a6f0fc11 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -288,12 +288,16 @@  config STRIP_ASM_SYMS
 
 config READABLE_ASM
 	bool "Generate readable assembler code"
-	depends on DEBUG_KERNEL
-	help
-	  Disable some compiler optimizations that tend to generate human unreadable
-	  assembler output. This may make the kernel slightly slower, but it helps
-	  to keep kernel developers who have to stare a lot at assembler listings
-	  sane.
+    depends on DEBUG_KERNEL
+    help
+      Disable some compiler optimizations that tend to generate human unreadable
+      assembler output. This may make the kernel slightly slower, but it helps
+      to keep kernel developers who have to stare a lot at assembler listings
+      sane.
+	  
+config DEBUG_FS
+	bool "Debug Filesystem"
+	select SIMPLEFS
 
 config HEADERS_INSTALL
 	bool "Install uapi headers to usr/include"
diff --git a/security/Kconfig b/security/Kconfig
index cd3cc7da3a55..2c6713aa8b4f 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -39,6 +39,7 @@  config SECURITY_WRITABLE_HOOKS
 
 config SECURITYFS
 	bool "Enable the securityfs filesystem"
+	select SIMPLEFS
 	help
 	  This will build the securityfs filesystem.  It is currently used by
 	  various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 828bb1eb77ea..d62d3fca47f2 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -18,7 +18,7 @@ 
 #include <linux/namei.h>
 #include <linux/capability.h>
 #include <linux/rcupdate.h>
-#include <linux/fs.h>
+#include <linux/simplefs.h>
 #include <linux/fs_context.h>
 #include <linux/poll.h>
 #include <linux/zlib.h>
@@ -2529,6 +2529,7 @@  static int aa_mk_null_file(struct dentry *parent)
 	struct vfsmount *mount;
 	struct dentry *dentry;
 	struct inode *inode;
+	int error;
 
 	mount = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL);
 	if (IS_ERR(mount))
diff --git a/security/inode.c b/security/inode.c
index 6c326939750d..a9a9ee4de21d 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -12,7 +12,7 @@ 
 /* #define DEBUG */
 #include <linux/sysfs.h>
 #include <linux/kobject.h>
-#include <linux/fs.h>
+#include <linux/simplefs.h>
 #include <linux/fs_context.h>
 #include <linux/mount.h>
 #include <linux/pagemap.h>