Commit 93b07113 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
Browse files

introduce memory_read_from_buffer() 



This patch introduces memory_read_from_buffer().

The only difference between memory_read_from_buffer() and
simple_read_from_buffer() is which address space the function copies to.

simple_read_from_buffer copies to user space memory.
memory_read_from_buffer copies to normal memory.

Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Doug Warzecha <Douglas_Warzecha@dell.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Cc: Abhay Salunke <Abhay_Salunke@dell.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Markus Rechberger <markus.rechberger@amd.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Bob Moore <robert.moore@intel.com>
Cc: Thomas Renninger <trenn@suse.de>
Cc: Len Brown <lenb@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Cc: Michael Holzheu <holzheu@de.ibm.com>
Cc: Brian King <brking@us.ibm.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Andrew Vasquez <linux-driver@qlogic.com>
Cc: Seokmann Ju <seokmann.ju@qlogic.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3527fb32

fs/libfs.c

+18 −0
Original line number Diff line number Diff line
@@ -528,6 +528,23 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, 
	return count;

}



ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,

				const void *from, size_t available)

{

	loff_t pos = *ppos;



	if (pos < 0)

		return -EINVAL;

	if (pos >= available)

		return 0;

	if (count > available - pos)

		count = available - pos;

	memcpy(to, from + pos, count);

	*ppos = pos + count;



	return count;

}



/*

 * Transaction based IO.

 * The file expects a single write which triggers the transaction, and then
@@ -800,6 +817,7 @@ EXPORT_SYMBOL(simple_statfs); 
EXPORT_SYMBOL(simple_sync_file);

EXPORT_SYMBOL(simple_unlink);

EXPORT_SYMBOL(simple_read_from_buffer);

EXPORT_SYMBOL(memory_read_from_buffer);

EXPORT_SYMBOL(simple_transaction_get);

EXPORT_SYMBOL(simple_transaction_read);

EXPORT_SYMBOL(simple_transaction_release);

include/linux/fs.h

+4 −1
Original line number Diff line number Diff line
@@ -2000,7 +2000,10 @@ extern int simple_fill_super(struct super_block *, int, 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 *, size_t, loff_t *, const void *, size_t);

extern ssize_t simple_read_from_buffer(void __user *to, size_t count,

			loff_t *ppos, const void *from, size_t available);

extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,

			const void *from, size_t available);



#ifdef CONFIG_MIGRATION

extern int buffer_migrate_page(struct address_space *,

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